We read with interest this article by Ong HS et al on “Evolution of therapies for the corneal endothelium: past, present and future approaches”.
As the article mentions, Rho kinase (ROCK) inhibitors have been described in the regenerative approach to corneal endothelial injury by aiding cell proliferation.1 Due to the wide range of cellular responses controlled by the Rho kinase signalling pathway, ROCK inhibitors play a part in increasing cell adhesion and proliferation of the corneal endothelium. Their clinical use has also been reported with success in Fuch’s endothelial dystrophy and pseudophakic corneal decompensation. 0.4% Ripasudil eye drop is the common agent used in these studies.2
Enriching nutrients, antibiotics and other additives have been described in literature to add value to corneal preservation media. It would be interesting to see if addition a Rho kinase inhibitor to the donor corneal preservation medium could enhance the endothelial cell count or limit attrition over longer preservation times. The parameters of the drop in terms of strength, solubility, minimum concentration, side effects if any etc. need to be evaluated prior. Of all the methods described to improve the corneal endothelial health, this is the only one that may be extrapolated to donor corneal tissue also, for better surgical outcomes
It may be worthwhile to test if adding a ROCK inhibitor may enhance donor corneal tissue viability in storage media, under controlled...
We read with interest this article by Ong HS et al on “Evolution of therapies for the corneal endothelium: past, present and future approaches”.
As the article mentions, Rho kinase (ROCK) inhibitors have been described in the regenerative approach to corneal endothelial injury by aiding cell proliferation.1 Due to the wide range of cellular responses controlled by the Rho kinase signalling pathway, ROCK inhibitors play a part in increasing cell adhesion and proliferation of the corneal endothelium. Their clinical use has also been reported with success in Fuch’s endothelial dystrophy and pseudophakic corneal decompensation. 0.4% Ripasudil eye drop is the common agent used in these studies.2
Enriching nutrients, antibiotics and other additives have been described in literature to add value to corneal preservation media. It would be interesting to see if addition a Rho kinase inhibitor to the donor corneal preservation medium could enhance the endothelial cell count or limit attrition over longer preservation times. The parameters of the drop in terms of strength, solubility, minimum concentration, side effects if any etc. need to be evaluated prior. Of all the methods described to improve the corneal endothelial health, this is the only one that may be extrapolated to donor corneal tissue also, for better surgical outcomes
It may be worthwhile to test if adding a ROCK inhibitor may enhance donor corneal tissue viability in storage media, under controlled conditions.
REFERENCES:
1. Okumura N, Okazaki Y,Inoue R, Kazuya Kakutani, et al. Effect of the Rho-Associated Kinase Inhibitor Eye Drop (Ripasudil) on Corneal Endothelial Wound Healing. Invest. Ophthalmol. Vis. Sci. 2016;57(3):1284-1292.
2. Moshirfar M, Parker L, Birdsong OC, et al. Use of Rho kinase Inhibitors in Ophthalmology: A Review of the Literature. Med Hypothesis Discov Innov Ophthalmol. 2018;7(3):101-111.
Eyes with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast vision from increased glare even if high-contrast acuity is not affected.1 In a retrospective study, Augustin and colleagues suggested that corneal guttae without edema contribute to decreased contrast sensitivity, and that such eyes would benefit from Descemet membrane endothelial keratoplasty (DMEK).2 The topic is important because it is unknown whether guttae in the absence of any corneal edema affect vision and therefore whether such eyes truly benefit from DMEK. The authors enrolled eyes with >5 mm of confluent guttae and without edema (modified Krachmer grade 5); however, they did not state their definition of “edema”. In FECD, when corneal edema is not clinically detectable by slit-lamp examination, it can be detected by Scheimpflug tomography.3 A recent study found evidence of subclinical corneal edema in 88% of eyes with FECD grade 5 and almost 40% of eyes with lesser grades of FECD.4 It is therefore highly likely that many of the FECD eyes examined by Augustin and colleagues did in fact have subclinical corneal edema, so can the authors examine the Scheimpflug tomograms of these eyes and report the contrast sensitivity results based on the presence or absence of subclinical edema? This is important because reduced contrast sensitivity might be caused by subclinical edema and not simply by “guttae without edema”, and cornea surgeons should not conclude that it is appr...
Eyes with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast vision from increased glare even if high-contrast acuity is not affected.1 In a retrospective study, Augustin and colleagues suggested that corneal guttae without edema contribute to decreased contrast sensitivity, and that such eyes would benefit from Descemet membrane endothelial keratoplasty (DMEK).2 The topic is important because it is unknown whether guttae in the absence of any corneal edema affect vision and therefore whether such eyes truly benefit from DMEK. The authors enrolled eyes with >5 mm of confluent guttae and without edema (modified Krachmer grade 5); however, they did not state their definition of “edema”. In FECD, when corneal edema is not clinically detectable by slit-lamp examination, it can be detected by Scheimpflug tomography.3 A recent study found evidence of subclinical corneal edema in 88% of eyes with FECD grade 5 and almost 40% of eyes with lesser grades of FECD.4 It is therefore highly likely that many of the FECD eyes examined by Augustin and colleagues did in fact have subclinical corneal edema, so can the authors examine the Scheimpflug tomograms of these eyes and report the contrast sensitivity results based on the presence or absence of subclinical edema? This is important because reduced contrast sensitivity might be caused by subclinical edema and not simply by “guttae without edema”, and cornea surgeons should not conclude that it is appropriate to offer DMEK for any eye with guttae. Surgeons and clinicians should recognize that Scheimpflug tomography patterns, which are easily acquired and repeatable,5 are more helpful than guttae assessment for guiding clinical decision-making in FECD.4
References
1. van der Meulen IJ, Patel SV, Lapid-Gortzak R, Nieuwendaal CP, McLaren JW, van den Berg TJ. Quality of vision in patients with Fuchs endothelial dystrophy and after Descemet stripping endothelial keratoplasty. Arch Ophthalmol 2011;129:1537-1542.
2. Augustin VA, Weller JM, Kruse FE, Tourtas T. Influence of corneal guttae and nuclear cataract on contrast sensitivity. Br J Ophthalmol 2020.
3. Sun SY, Wacker K, Baratz KH, Patel SV. Determining Subclinical Edema in Fuchs Endothelial Corneal Dystrophy. Revised Classification using Scheimpflug Tomography for Preoperative Assessment. Ophthalmology 2019;126:195-204.
4. Patel SV, Hodge DO, Treichel EJ, Spiegel MR, Baratz KH. Predicting the Prognosis of Fuchs Endothelial Corneal Dystrophy by using Scheimpflug Tomography. Ophthalmology 2020;127:315-323.
5. Patel SV, Hodge DO, Treichel EJ, Spiegel MR, Baratz KH. Repeatability of Scheimpflug Tomography for Assessing Fuchs Endothelial Corneal Dystrophy. Am J Ophthalmol 2020;215:91-103.
We thank Svasti-Salee, Snead and Alexander [1] for their interest in our study and their comment regarding the reliability of spectral domain optical coherence tomography (SD-OCT) in differentiating a completely attached hyaloid versus complete posterior vitreous detachment (PVD).
To address the author’s question, in our post-hoc analysis, only SD-OCT was used to diagnose PVD status. A slit-lamp examination specifically assessing for PVD was not performed per protocol in the TREND study, [2] therefore data other than SD-OCT were not available for post-hoc analysis.
The accepted clinical methods to determine PVD include slit-lamp examination, dynamic ultrasonography and SD-OCT, while previous generations of OCT (time-domain OCT) potentially offered insufficient resolution and field of view. Of those methods, SD-OCT has the main advantage of being operator independent and allowing systematic, standardized evaluation in a reading center setting. The approach chosen for the analysis of the TREND dataset has been repeatedly performed in several prior studies, with similar outcome data. [3-5]
A recent study cited by the authors [6] reports that PVD status on SD-OCT did not correlate well to intraoperative findings when patients underwent vitrectomy. However, vitrectomy surgery is performed in patients with vitreomacular interface disease, where often a multi-layered posterior vitreous cortex cleaving into separate planes is found, making...
We thank Svasti-Salee, Snead and Alexander [1] for their interest in our study and their comment regarding the reliability of spectral domain optical coherence tomography (SD-OCT) in differentiating a completely attached hyaloid versus complete posterior vitreous detachment (PVD).
To address the author’s question, in our post-hoc analysis, only SD-OCT was used to diagnose PVD status. A slit-lamp examination specifically assessing for PVD was not performed per protocol in the TREND study, [2] therefore data other than SD-OCT were not available for post-hoc analysis.
The accepted clinical methods to determine PVD include slit-lamp examination, dynamic ultrasonography and SD-OCT, while previous generations of OCT (time-domain OCT) potentially offered insufficient resolution and field of view. Of those methods, SD-OCT has the main advantage of being operator independent and allowing systematic, standardized evaluation in a reading center setting. The approach chosen for the analysis of the TREND dataset has been repeatedly performed in several prior studies, with similar outcome data. [3-5]
A recent study cited by the authors [6] reports that PVD status on SD-OCT did not correlate well to intraoperative findings when patients underwent vitrectomy. However, vitrectomy surgery is performed in patients with vitreomacular interface disease, where often a multi-layered posterior vitreous cortex cleaving into separate planes is found, making an accurate diagnosis challenging. Obviously, vitrectomy cannot be used for “diagnostic” purposes.
In contrast, patients with neovascular age-related macular degeneration (AMD) are considered to follow the usual age-dependent evolution of vitreomacular detachment [7], where a complete separation of the posterior vitreous cortex is the most common configuration in people over 70.
In summary, we argue that the authors’ concern may apply less to an AMD patient population, but rather to eyes with vitreomacular interface disease. In patients with AMD, we consider SD-OCT the gold standard for diagnosing the clinical stages of PVD, including differentiation between complete PVD and posterior vitreous attachment.
1 Svasti-Salee CR, Snead MP, Alexander P. Response to 'Effect of posterior vitreous detachment on treat-and-extend versus monthly ranibizumab for neovascular age-related macular degeneration'. Br J Ophthalmol e-letter
2 Silva R, Berta A, Larsen M, et al. Treat-and-Extend versus Monthly Regimen in Neovascular Age-Related Macular Degeneration: Results with Ranibizumab for the TREND Study. Ophthalmology 2018;125(1):57-65.
3 Mayr-Sponer U, Waldstein SM, Kundi M, et al. Influence of the vitreomacular interface on outcomes of ranibizumab therapy in neovascular age-related macular degeneration. Ophthalmology 2013;120(12):2620-29.
4 Ciulla TA, Ying GS, Maguire MG, et al. Influence of the vitreomacular interface on treatment outcomes in the comparison of age-related macular degeneration treatments trials. Ophthalmology 2015;122(6):1203-11.
5 Waldstein SM, Montuoro A, Podkowinski D, et al. Evaluating the impact of vitreomacular adhesion on anti-VEGF therapy for retinal vein occlusion using machine learning. Sci Rep 2017;7(1):2928.
6 Hwang ES, Kraker JA, Griffin KJ, et al. Accuracy of spectral-domain OCT of the macula for detection of complete posterior vitreous detachment. Ophthalmol Retina 2020;4(2):148-153.
7 Itakura H, Kishi S. Evolution of vitreomacular detachment in healthy subjects. JAMA Ophthalmol. 2013;131(10):1348-52.
We thank Dr. Shukla for his interest in our article and his comments 1, 2.
In our study all consecutive cases of rhegmatogenous retinal detachment (RD) that underwent pars plana vitrectomy (PPV) were included in the study regardless of complexity, type of tear, lens or refractive status, or use of supplemental buckle in order to reduce selection bias and to allow study of various subgroups of patients. For the same reason the 13 cases with silicone oil present at the time of last follow-up were not excluded. The paper referenced by Dr. Shukla reports a retinal re-detachment rate of 13.2% after removal of silicone oil (ROSO), with many of the cases performed prior to the era of small gauge vitrectomy and wide-angle viewing systems (WAVS) 3. Encircling endolaser photocoagulation further reduces the re-detachment rate to 8.6% 4. More recent surgical techniques are likely associated with a lower retinal re-detachment rate. Nevertheless, a presumed retinal re-detachment of 13.2% following ROSO corresponds to an estimated 1.7 eyes with recurrent RD out of the 13 eyes with residual silicone oil in our series 3. This in turn corresponds to a 0.5% difference in the overall single surgery success rate (SSSR) in 312 eyes. It could therefore be safely assumed that inclusion of the small group with silicone oil at the last follow-up visit did not affect the overall success rate significantly, but reduced chances of introducing a selection bias.
We thank Dr. Shukla for his interest in our article and his comments 1, 2.
In our study all consecutive cases of rhegmatogenous retinal detachment (RD) that underwent pars plana vitrectomy (PPV) were included in the study regardless of complexity, type of tear, lens or refractive status, or use of supplemental buckle in order to reduce selection bias and to allow study of various subgroups of patients. For the same reason the 13 cases with silicone oil present at the time of last follow-up were not excluded. The paper referenced by Dr. Shukla reports a retinal re-detachment rate of 13.2% after removal of silicone oil (ROSO), with many of the cases performed prior to the era of small gauge vitrectomy and wide-angle viewing systems (WAVS) 3. Encircling endolaser photocoagulation further reduces the re-detachment rate to 8.6% 4. More recent surgical techniques are likely associated with a lower retinal re-detachment rate. Nevertheless, a presumed retinal re-detachment of 13.2% following ROSO corresponds to an estimated 1.7 eyes with recurrent RD out of the 13 eyes with residual silicone oil in our series 3. This in turn corresponds to a 0.5% difference in the overall single surgery success rate (SSSR) in 312 eyes. It could therefore be safely assumed that inclusion of the small group with silicone oil at the last follow-up visit did not affect the overall success rate significantly, but reduced chances of introducing a selection bias.
In our series a supplemental encircling scleral buckle (SB) (42 silicone band) was used in 34% of the eyes. Throughout the study there was a decreasing trend in the use of supplemental SB while the outcomes remained stable. This has been discussed in detail in a sequel publication5. Dr. Shukla comments, “the optional use of scleral buckle in this study is confusing”. It is clear from the data that good anatomic outcomes may be achieved with PPV without vitreous base (VB) shaving in both PPV and PPV+SB groups. The author further states “the vitreous base-shaving is critical to anatomical success when no encirclage is used”. This is an assumption that is not supported by the findings of our study: 195 (94.7%) of 206 eyes without SB had reattachment of the retina with a single surgery. The reference that is provided is a retrospective series of RDs that underwent PPV and silicone oil between 2000 and 2012, many of which were presumably performed without the use of small gauge vitrectomy or WAVS3. The study retrospectively identified vitreous remnants during retinal re-detachment surgery and equated this finding to inadequate VB shaving rather than inadequate vitreous removal. Using WAVS, it is possible to visualize the retina periphery to the vicinity of the VB and remove the peripheral vitreous effectively without a need for scleral depressed shaving of the VB6. Removal of clinically significant peripheral vitreous without VB shaving avoids leaving significant amounts of vitreous remnant and is compatible with good anatomic success rate. Dr. Shukla states “the authors reported no additional benefit from buckling”. We reported, “the single-surgery success rate was similar in eyes with and without SB (95.2% and 94.7%)” and cautioned against comparative interpretation of these findings as eyes with SB likely had more complex retinal detachments. Dr. Shukla further comments “We therefore do not have clarity about the one moot issue this study could settle: whether vitrectomy sans base-shaving is good enough for simple RD at least”. The answer to this comment-question is clear: Using WAVS and small gauge vitrectomy systems, vitrectomy without routine prophylactic scleral depressed shaving of VB may be associated with good anatomic outcomes (95% SSSR) for retinal detachments with a range of complexities including simple RDs2.
A recent report by Sohn and colleagues detailed the characteristics and outcomes of retinal detachment surgery for eyes with posteriorly inserted vitreous base (PIVB)7. The authors suggested encircling endolaser photocoagulation or supplemental scleral buckle in these cases. In our series, PIVB was noted in a minority of cases. In these cases encircling endolaser photocoagulation was performed posterior to the insertion of the vitreous base with additional septate pattern in each quadrant. Supplemental SB was considered if retinal detachment with multiple tears was present inferiorly. While a thorough removal of peripheral vitreous makes clinical sense, there is no evidence in the literature that shaving of the vitreous base improves anatomic outcomes in cases with PIVB.
In our series, GRTs measured from 3 to 11 clock hours, with the majority measuring between 4-6 clock hours. Proliferative vitreoretinopathy ranged from none to funnel retinal detachment. Seven (50%) of 14 eyes with GRT had supplemental SB, 11 (79%) eyes had silicone oil tamponade, and 2 of the 8 phakic eyes had removal of cataractous lens in order to improve visualization. At the last follow-up, silicone oil was present in 3 eyes. Dr. Shukla comments that vitreous base shaving is considered non-negotiable in a GRT and references a review article on GRT by Shunmugam and colleagues 8. The article cites 2 studies published in 1981 and 1992 in support of shaving of the vitreous base in the management of RD associated with GRT9, 10. Interestingly, within the same section, it is stated “opposite the GRT, however, because of the adherence of the vitreous base, limited vitrectomy is advisable to avoid circumferential extension of the GRT or the formation of further retinal breaks”. It appears that shaving of the vitreous base has uncertain merit for these cases. In the area corresponding to GRT, the VB is partly removed during removal of the anterior flap of the GRT and the remainder covers the surface of pars plana. In the area outside of the GRT, retinal laser photocoagulation applied posterior to the VB margin reduces risk of retinal detachment originating from this area.
In summary, introduction of 3-port pars plana vitrectomy in the 1970s transformed management of retinal detachment. Some of the early reports suggested that shaving of the VB may be associated with improved outcomes. Since the early days of PPV, many advances have been made including the introduction of endolaser photocoagulation, perfluorocarbon heavy liquid, WAVS, sclerotomy cannula systems, fast cutting small gauge vitrectomy systems, high precision microinstrumentation, chromophore-assisted visualization of the vitreous and preretinal membranes, and effective ocular anti-inflammatory pharmacotherapy. With continued advances in vitrectomy surgery, there is a need for reevaluation and modification of our surgical techniques.
Bonafede et al1 analyzed the change over time in hypermetropia in children from the USA with partially and fully accommodative esotropia. This study complements a previous long-term follow-up multi-center publication on 164 hypermetropic children from USA, Germany, and Israel2. The follow-up was comparable: ages 3.5-10.5 years in the previous article compared to 3-12 years in the current paper. The range of spherical equivalent refractive error in the previous paper was categorized as +1-3Diopters (D) (mild hypermetropes) and +5-8D (high hypermetropes). In contrast, the current study included also moderate hypermetropes, because it involved a group with less than +4D hypermetropes and a group of children with hypermetropia of +4D or more. Esotropia in the previous study was not present in any of the mild hypermetropes but was present in half (48%) of the high hypermetropes. Due to a decrease in hypermetropia over time beyond the age of 6 years old, mild hypermetropes in the previous study were weaned from glasses (-0.095 D/year), while the high hypermetropes remained in glasses (-0.037 D/year). Similarly, because of a mean decrease of -0.17 D/year that occurred only from age 7 to 15 years, subjects in the current study with a “smaller baseline” (i.e., mild) hypermetropia stopped wearing glasses. However, most moderate and high hypermetropes beyond the age of 12 years remained in glasses (-0.18 D/year).
Bonafede et al1 analyzed the change over time in hypermetropia in children from the USA with partially and fully accommodative esotropia. This study complements a previous long-term follow-up multi-center publication on 164 hypermetropic children from USA, Germany, and Israel2. The follow-up was comparable: ages 3.5-10.5 years in the previous article compared to 3-12 years in the current paper. The range of spherical equivalent refractive error in the previous paper was categorized as +1-3Diopters (D) (mild hypermetropes) and +5-8D (high hypermetropes). In contrast, the current study included also moderate hypermetropes, because it involved a group with less than +4D hypermetropes and a group of children with hypermetropia of +4D or more. Esotropia in the previous study was not present in any of the mild hypermetropes but was present in half (48%) of the high hypermetropes. Due to a decrease in hypermetropia over time beyond the age of 6 years old, mild hypermetropes in the previous study were weaned from glasses (-0.095 D/year), while the high hypermetropes remained in glasses (-0.037 D/year). Similarly, because of a mean decrease of -0.17 D/year that occurred only from age 7 to 15 years, subjects in the current study with a “smaller baseline” (i.e., mild) hypermetropia stopped wearing glasses. However, most moderate and high hypermetropes beyond the age of 12 years remained in glasses (-0.18 D/year).
In conclusion, data derived from both studies, pertaining to children with or without esotropia, reveals that only mild hypermetropes will be weaned from glasses in their teens. In contrast, moderate and high hypermetropes will remain in glasses. We congratulate the authors of the current study for their contribution that makes it possible based on data collated from around the world to inform parents whether their child will need glasses beyond childhood.
References:
1. Bonafede L, Bender L, Shaffer J, et al. Refractive change in children with accommodative esotropia. British Journal of Ophthalmology 2020;104:1283-1287.
2. Mezer E, Meyer E, Wygnanski-Jaffe T, Haase W, Shauly Y, Biglan AW. The long-term outcome of the refractive error in children with hypermetropia. Graefes Arch Clin Exp Ophthalmol. 2015;253(7):1013-1019.
To the Editor:
We appreciate the comments by Wei Gui and J. Sebag about Ozsaygili Cemal’s article titled ‘The effect of posterior vitreous detachment on aflibercept response in diabetic macular oedema.’1 In our study, we used the video display mode to obtain more reliable results while evaluating the posterior vitreous detachment (PVD) status with spectral-domain optical coherence tomography (SD-OCT). In a recent clinical study comparing the PVD status with ocular ultrasonography (US) and SD-OCT in patients with diabetic macular oedema (DMO), it was reported that video display mode SD-OCT showed total agreement (100% in video display mode) with US.2 We used the video display mode in all patients instead of a single cross-sectional view and excluded patients with poor image quality. Since it was a retrospective study, we could not have the chance to perform US, but excluding these patients from the study in patients where any of the 2 independent retina specialists (CO, BK) disagreed on the PVD status draws attention as factors that increase the validity of our data. In addition, the International Vitreomacular Traction Study Group, including doctor J. Sebag, has classified the posterior vitreous-macular relationship based on OCT and has mostly replaced USG with OCT in our current clinical practice.3
All eyes in our study were examined for vitreoschisis and similar anomalous PVD using SD-OCT video display mode. As you mentioned, SD-OCT has the abili...
To the Editor:
We appreciate the comments by Wei Gui and J. Sebag about Ozsaygili Cemal’s article titled ‘The effect of posterior vitreous detachment on aflibercept response in diabetic macular oedema.’1 In our study, we used the video display mode to obtain more reliable results while evaluating the posterior vitreous detachment (PVD) status with spectral-domain optical coherence tomography (SD-OCT). In a recent clinical study comparing the PVD status with ocular ultrasonography (US) and SD-OCT in patients with diabetic macular oedema (DMO), it was reported that video display mode SD-OCT showed total agreement (100% in video display mode) with US.2 We used the video display mode in all patients instead of a single cross-sectional view and excluded patients with poor image quality. Since it was a retrospective study, we could not have the chance to perform US, but excluding these patients from the study in patients where any of the 2 independent retina specialists (CO, BK) disagreed on the PVD status draws attention as factors that increase the validity of our data. In addition, the International Vitreomacular Traction Study Group, including doctor J. Sebag, has classified the posterior vitreous-macular relationship based on OCT and has mostly replaced USG with OCT in our current clinical practice.3
All eyes in our study were examined for vitreoschisis and similar anomalous PVD using SD-OCT video display mode. As you mentioned, SD-OCT has the ability to detect vitreoschisis.4,5 However, we had the chance to observe that the SD-OCT video display mode can make the fine distinction between vitreoschisis and artefact more reliably than single-section images and thanks to J. Sebag's letter for the opportunity to emphasize this once again. We think that the SD-OCT video imaging mode should be kept in mind by clinicians as it provides dynamic evaluation like USG and increases the reliability of static cross-sectional images which can rarely lead to erroneous interpretations.
We have applied the same number of injections to all eyes in our study and evaluated the short-term treatment response. However, as we mentioned in our study, further studies with longer follow-up are needed regarding the effects of PVD status on injection requirement. After intravitreal injection, larger molecules may be more exposed to the molecular sieve effect of Balaz’s in the posterior vitreous cortex6, but aflibercept also may be too small to be affected by the molecular sieve effect. Not only the presence of the attached posterior vitreous cortex but also vitreous glycation and different amounts of vitreous that had glycated cross-links and hyaluronan can also affect the permeability coefficient for diffusion7 and treatment response. The answer to whether the effect of the posterior vitreous on the treatment response is more than a mechanical barrier will be elucidated by future studies. We thank Dr. Wei Gui and J. Sebag for the interest in our study and we welcome further comments, questions, and suggestions.
Cemal OZSAYGILI, Bekir KUCUK, Yener YILDIRIM
None of the authors has any financial/conflicting interests to disclose.
References
1. Özsaygili C, Küçük B, Yildirim Y. The effect of posterior vitreous detachment on aflibercept response in diabetic macular oedema [published online ahead of print, 2020 Jul 29]. Br J Ophthalmol. 2020;bjophthalmol-2020-316155. doi:10.1136/bjophthalmol-2020-316155
2. Pessoa B, Coelho J, Malheiro L, et al. Comparison of Ocular Ultrasound Versus SD-OCT for Imaging of the Posterior Vitreous Status in Patients With DME. Ophthalmic Surg Lasers Imaging Retina. 2020;51(4):S50-S53. doi:10.3928/23258160-20200401-07
3. Duker, J. S., Kaiser, P. K., Binder, S., de Smet, M. D., Gaudric, A., Reichel, E., Sadda, S. R., Sebag, J., Spaide, R. F., & Stalmans, P. (2013). The International Vitreomacular Traction Study Group classification of vitreomacular adhesion, traction, and macular hole. Ophthalmology, 120(12), 2611–2619. https://doi.org/10.1016/j.ophtha.2013.07.042
4. Gupta, P., Yee, K. M., Garcia, P., Rosen, R. B., Parikh, J., Hageman, G. S., Sadun, A. A., & Sebag, J. (2011). Vitreoschisis in macular diseases. The British journal of ophthalmology, 95(3), 376–380. https://doi.org/10.1136/bjo.2009.175109
5. Sebag J. Vitreoschisis in diabetic macular edema. Invest Ophthalmol Vis Sci. 2011;52(11):8455-8456. doi:10.1167/iovs.11-8333.
6. Balazs EA. Die Mikrostruktur und Chemie des Glaskörpers [Microstructure and chemistry of the vitreous body]. Ber Zusammenkunft Dtsch Ophthalmol Ges. 1968;68:536-572.
7. Lee O-T, Good SD, Lamy R, et al. Advanced glycation end product accumulation reduces vitreous permeability. Invest Ophthalmol Vis Sci 2015;56:2892–2897.
We read with great interest the article entitled ‘Prevalence of guttae in the graft following corneal transplantation’ by Nahum et al, published in the May 2015 issue of the British Journal of Ophthalmology [1] . The authors reported the prevalence of cornea guttata postkeratoplasty in a large population of 1116 patients to be 4%. They also found that guttae postkeratoplasty do not negatively affect the visual acuity, endothelial cell density, or graft survival during the initial two postoperative years. The content of this article is important and well put, since this is the first study to reveal the prevalence and sequelae of postkeratoplasty guttae on the corneal graft.
Based on our clinical experience and on multiple published studies, the prevalence of cornea guttata in the normal population is estimated to be higher than 4% [2]. However, the low prevalence reached by Nahum et al, is explained mainly by the preoperative screening of the donor corneas for guttae, as stated in the article. Therefore, it would be very interesting if the authors can provide an estimation of the percentage of donor corneas that are usually discarded by the guttae screening in their eye bank.
Up to our knowledge, guttae are very often not detectable using inverted light microscopy, thus guttae screening as a part of the routine examination of the donor corneas is a challenging task. There is only one study performed by Borderie et al in 2001 [3], that aimed to detect the pres...
We read with great interest the article entitled ‘Prevalence of guttae in the graft following corneal transplantation’ by Nahum et al, published in the May 2015 issue of the British Journal of Ophthalmology [1] . The authors reported the prevalence of cornea guttata postkeratoplasty in a large population of 1116 patients to be 4%. They also found that guttae postkeratoplasty do not negatively affect the visual acuity, endothelial cell density, or graft survival during the initial two postoperative years. The content of this article is important and well put, since this is the first study to reveal the prevalence and sequelae of postkeratoplasty guttae on the corneal graft.
Based on our clinical experience and on multiple published studies, the prevalence of cornea guttata in the normal population is estimated to be higher than 4% [2]. However, the low prevalence reached by Nahum et al, is explained mainly by the preoperative screening of the donor corneas for guttae, as stated in the article. Therefore, it would be very interesting if the authors can provide an estimation of the percentage of donor corneas that are usually discarded by the guttae screening in their eye bank.
Up to our knowledge, guttae are very often not detectable using inverted light microscopy, thus guttae screening as a part of the routine examination of the donor corneas is a challenging task. There is only one study performed by Borderie et al in 2001 [3], that aimed to detect the presence of guttae during organ culture. Unfortunately, this study did not clearly describe the features of guttae detected using light microscopy, and the pictures provided did not show specific and distinct findings. Moreover, a clear association proving that the guttae suspected preoperatively in the eye bank correspond to the postoperative guttae detected by specular microscopy was missing.
Therefore, it would be of great importance to the eye banks on an international level to be informed in detail about the preoperative guttae screening process that was performed by Nahum et al, explaining the exact methods followed by their eye bank and clarifying the guttae features as visualized by inverted light microscopy.
References:
1. Nahum Y, Canton V, Ponzin D, Busin M. Prevalence of guttae in the graft following corneal transplantation. Br J Ophthalmol. 2015;99(12):1660-1663.
2. Zoega GM, Arnarsson A, Sasaki H, Söderberg PG, Jonasson F. The 7-year cumulative incidence of cornea guttata and morphological changes in the corneal endothelium in the Reykjavik Eye Study. Acta Ophthalmol. 2013;91(3):212-218.
3. Borderie VM, Sabolic V, Touzeau O, Scheer S, Carvajal-Gonzalez S, Laroche L. Screening human donor corneas during organ culture for the presence of guttae. Br J Ophthalmol. 2001;85(3):272-276.
We read with interest the study by Özsaygili et al. in which the authors report that the presence or absence of posterior vitreous detachment (PVD) purportedly had no influence on the efficacy of aflibercept intravitreal injections in patients with diabetic macular oedema (DMO). We question the validity of this conclusion since it is known that eyes with attached vitreous require more injections to manage exudative age-related macular degeneration than eyes with PVD.1 This is presumed to be due to interference with macular access by anti-vascular endothelial growth factor (anti-VEGF) by the posterior vitreous cortex. The same mechanism of action could be expected in eyes with DMO. Thus, there may be alternative explanations for the observed lack of an effect of PVD status on the response to aflibercept. We hypothesize that the findings are due to both the unreliable diagnosis of PVD by spectral domain optical coherence tomography (SD-OCT) alone, and the possible presence of vitreoschisis.
Previous studies have shown that SD-OCT is not a robust way to diagnose PVD, since the positive predictive value is only approximately 50%.2, 3 Rather, ultrasound is the recommended way to detect complete PVD (Figure 1).2 Did Özsaygili et al. perform ultrasound in their patients? If not, they would be unable to determine true PVD status, and the validity of their conclusion needs to be called into question.
Additionally, it is unclear from the study by Özsaygili et al. wheth...
We read with interest the study by Özsaygili et al. in which the authors report that the presence or absence of posterior vitreous detachment (PVD) purportedly had no influence on the efficacy of aflibercept intravitreal injections in patients with diabetic macular oedema (DMO). We question the validity of this conclusion since it is known that eyes with attached vitreous require more injections to manage exudative age-related macular degeneration than eyes with PVD.1 This is presumed to be due to interference with macular access by anti-vascular endothelial growth factor (anti-VEGF) by the posterior vitreous cortex. The same mechanism of action could be expected in eyes with DMO. Thus, there may be alternative explanations for the observed lack of an effect of PVD status on the response to aflibercept. We hypothesize that the findings are due to both the unreliable diagnosis of PVD by spectral domain optical coherence tomography (SD-OCT) alone, and the possible presence of vitreoschisis.
Previous studies have shown that SD-OCT is not a robust way to diagnose PVD, since the positive predictive value is only approximately 50%.2, 3 Rather, ultrasound is the recommended way to detect complete PVD (Figure 1).2 Did Özsaygili et al. perform ultrasound in their patients? If not, they would be unable to determine true PVD status, and the validity of their conclusion needs to be called into question.
Additionally, it is unclear from the study by Özsaygili et al. whether vitreoschisis, defined as a split within the posterior vitreous cortex (Figure 2), was observed or documented. Although SD-OCT has the ability to detect vitreoschisis4–6, “what we see depends mainly on what we look for”, as Sir John William Lubbock once wrote. If there were cases in the series assembled by Özsaygili et al. with anomalous PVD and vitreoschisis, this could be incorrectly diagnosed as PVD, and the access of aflibercept into the macula may have been hindered by the outer wall of the vitreoschisis cavity (Figure 2), giving another reason for the false impression that PVD plays no role on aflibercept response in patients with diabetic macular oedema.
In conclusion, we agree with Sir Lubbock that we see what we seek and thus invite the authors to re-examine their data with the foregoing in mind.
References:
1. Sebag J. Vitreous in age-related macular degeneration therapy - The medium is the message. Retina. 2015;35(9):1715-1718. doi:10.1097/IAE.0000000000000718.
2. Hwang ES, Kraker JA, Griffin KJ, Sebag J, Weinberg D V, Kim JE. Accuracy of Spectral-Domain OCT of the Macula for Detection of Complete Posterior Vitreous Detachment. Ophthalmol Retin. 2020;4(2):148-153. doi:10.1016/j.oret.2019.10.013.
3. Abraham JR, Ehlers JP. Posterior Vitreous Detachment: Methods for Detection. Ophthalmol Retin. 2020;4(2):119-121. doi:10.1016/j.oret.2019.12.014.
4. Sebag J. Vitreoschisis. Graefe’s Arch Clin Exp Ophthalmol. 2008;246(3):329-332. doi:10.1007/s00417-007-0743-x.
5. Gupta P, Yee KMP, Garcia P, et al. Vitreoschisis in macular diseases. Br J Ophthalmol. 2011;95(3):376-380. doi:10.1136/bjo.2009.175109.
6. Sebag J. Vitreoschisis in diabetic macular edema. Invest Ophthalmol Vis Sci. 2011;52(11):8455-8456. doi:10.1167/iovs.11-8333.
We read with interest the post-hoc study by Waldstein and colleagues concerning the impact of posterior vitreous detachment (PVD) on the efficacy of anti-VEGF treatment in neovascular age-related macular degeneration (AMD). However, the reliability of spectral-domain optical coherence tomography (SD-OCT) in confirming PVD status, upon which the findings of this study are dependent, is questionable.[1, 2] In particular, OCT is poor at distinguishing between fully attached vitreous and complete PVD.
Hwang et al recently reported limited sensitivity of SD-OCT in detecting complete PVD when compared to clinical findings at the time of vitrectomy.[1] It was found that among patients awaiting vitrectomy, OCT diagnosis of complete PVD (based on the absence of visible posterior vitreous cortex or a premacular bursa on SD-OCT) had a positive predictive value of just 53% when compared to intra-operative findings.
PVD remains a clinical diagnosis that is based on the identification of the posterior hyaloid membrane (PHM), a diaphanous, wrinkled film observable during biomicroscopic examination. The Weiss ring which it incorporates is a more variable and less reliable confirmatory sign of PHM detachment from the optic nerve head. The visible PHM is a consistent clinical finding in patients with PVD and correlates histopathologically with a type IV collagen basement membrane which begins life attached to the retina as the internal limiting membrane.[3...
We read with interest the post-hoc study by Waldstein and colleagues concerning the impact of posterior vitreous detachment (PVD) on the efficacy of anti-VEGF treatment in neovascular age-related macular degeneration (AMD). However, the reliability of spectral-domain optical coherence tomography (SD-OCT) in confirming PVD status, upon which the findings of this study are dependent, is questionable.[1, 2] In particular, OCT is poor at distinguishing between fully attached vitreous and complete PVD.
Hwang et al recently reported limited sensitivity of SD-OCT in detecting complete PVD when compared to clinical findings at the time of vitrectomy.[1] It was found that among patients awaiting vitrectomy, OCT diagnosis of complete PVD (based on the absence of visible posterior vitreous cortex or a premacular bursa on SD-OCT) had a positive predictive value of just 53% when compared to intra-operative findings.
PVD remains a clinical diagnosis that is based on the identification of the posterior hyaloid membrane (PHM), a diaphanous, wrinkled film observable during biomicroscopic examination. The Weiss ring which it incorporates is a more variable and less reliable confirmatory sign of PHM detachment from the optic nerve head. The visible PHM is a consistent clinical finding in patients with PVD and correlates histopathologically with a type IV collagen basement membrane which begins life attached to the retina as the internal limiting membrane.[3-5]
We would be interested to learn whether the baseline evaluation of the patients in the reported study included a clinical assessment of PVD status and whether clinical separation of the posterior hyaloid membrane correlated with response to anti-VEGF therapy. We agree with the authors that there is evidence that PVD status may significantly impact the response of neovascular AMD to anti-VEGF therapy but SD-OCT must be combined with meticulous clinical slit-lamp examination to reliably determine the true status of the posterior hyaloid membrane.
1 Hwang ES, Kraker JA, Griffin KJ, et al. Accuracy of spectral-domain OCT of the macula for detection of complete posterior vitreous detachment. Ophthalmol Retina 2020;4(2):148-153.
2 Kičová N, Bertelmann T, Irle S, et al. Evaluation of a posterior vitreous detachment: a comparison of biomicroscopy, B-scan ultrasonography and optical coherence tomography to surgical findings with chromodissection. Acta Ophthalmol 2012;90(4):e264-268.
3 Snead MP, Snead DR, James S, et al. Clinicopathological changes at the vitreoretinal junction: posterior vitreous detachment. Eye (Lond) 2008;22(10):1257–1262.
4 Snead MP, Snead DRJ, Richards AJ, et al. Clinical, histological and ultrastructural studies of the posterior hyaloid membrane. Eye (Lond) 2002;16(4),447-453.
5 Fincham GS, James S, Spickett C, et al. Posterior vitreous detachment and the posterior hyaloid membrane. Ophthalmology 2018;125(2):227-236.
Dr. Portabella reviewed the stability of 345 consecutive cases of scleral-sutured posterior chamber IOLs retrospectively.1 In discussing sutured scleral-fixated IOLs several main points must be considered: 1) type of suture utilized; 2) length of follow-up; 3) multiple surgeons or single surgeon; 4) type of knot utilized; and 5) reoperation rate.
This paper by Portabella et al.1 involved use of Prolene (polypropylene) or Mersilene sutures, follow-up with a maximum of 10 years, multiple surgeons, a knot with a single loop through the sclera and around the haptic, and a reoperation rate of 7.2%. The Vote et al study2 reviewed 61 eyes with Prolene sutures, follow-up with a maximum of 10.6 years, multiple surgeons, variable knots, and an extremely high rate of redislocation of 26.2%, which they postulated was due to suture breakage. This high rate of redislocation has not been confirmed in any other study.3,4
A recent study by Kokame et al3 involved 118 eyes utilizing 10-0 Prolene sutures, a single surgeon, follow-up of up to 24.75 years, a knot with two sutures - one secured to the haptic by a cow-hitch and the other to the sclera with both sutures tied together in a single knot under a scleral flap, and a broken suture rate of 0.5% (1/214 fixation sutures). The maximum follow-up of 24.75 years with stable fixation strongly supports the stability of 10-0 Prolene. Higher rates of redislocations of sutured scleral-fixated IOLs can be due to multiple surgeo...
Dr. Portabella reviewed the stability of 345 consecutive cases of scleral-sutured posterior chamber IOLs retrospectively.1 In discussing sutured scleral-fixated IOLs several main points must be considered: 1) type of suture utilized; 2) length of follow-up; 3) multiple surgeons or single surgeon; 4) type of knot utilized; and 5) reoperation rate.
This paper by Portabella et al.1 involved use of Prolene (polypropylene) or Mersilene sutures, follow-up with a maximum of 10 years, multiple surgeons, a knot with a single loop through the sclera and around the haptic, and a reoperation rate of 7.2%. The Vote et al study2 reviewed 61 eyes with Prolene sutures, follow-up with a maximum of 10.6 years, multiple surgeons, variable knots, and an extremely high rate of redislocation of 26.2%, which they postulated was due to suture breakage. This high rate of redislocation has not been confirmed in any other study.3,4
A recent study by Kokame et al3 involved 118 eyes utilizing 10-0 Prolene sutures, a single surgeon, follow-up of up to 24.75 years, a knot with two sutures - one secured to the haptic by a cow-hitch and the other to the sclera with both sutures tied together in a single knot under a scleral flap, and a broken suture rate of 0.5% (1/214 fixation sutures). The maximum follow-up of 24.75 years with stable fixation strongly supports the stability of 10-0 Prolene. Higher rates of redislocations of sutured scleral-fixated IOLs can be due to multiple surgeons inexperienced with secure knot tying with the slippery Prolene suture, and knot integrity of a single loop around the haptic through the sclera with one suture knot creating the scleral fixation. Histopathologic studies of 10-0 Prolene sutures do not show evidence of cracking, wrinkling, flaking, or degradation of 10-0 Prolene sutures 10.5 years after placement.5
Gregg T Kokame MD MMM
Chief of Ophthalmology
University of Hawaii School of Medicine
Honolulu, Hawaii, USA
References:
1. Portabella M, Nadal J, Alarex de Toledo J et al. Long-term outcome of scleral-sutured posterior chamber intraocular lens: a case series. Br J Ophthalmol 2020;104:712-717. Doi: 10.1136/brjophthalmol-2019-314054.
2. Vote BJ, Tranos P, Bunce C, Charteris DG, Da Cruz L. Long term outcome of combined pars plana vitrectomy and scleral fixated posterior chamber intraocular lens implantation. Am J Ophthalmol 2006; 141(2):308-312. doi:10.1016/j.ajo.2005.09.012
3. Kokame GT, Yanagihara RT, Shantha JG, Kaneko KN, Long Term Outcome of Pars Plana Vitrectomy and Sutured Scleral-Fixated Posterior Chamber Intraocular Lens Implantation or Repositioning, American Journal of Ophthalmology 2018 May;189:10-16. doi: 10.1016/j.ajo.2018.01.034
4. Bading G, Hillenkamp J, Sachs HG, Gabel VP, Framme C. Long-term safety and functional outcome of combined pars plana vitrectomy and scleral-fixated sutured posterior chamber lens implantation. Am J Ophthalmol 2007;144(3):371–377. doi: 10.1016/j.ajo.2007.05.014.
5. Parekh P, Green WR, Stark WJ, Akpek EK. Subluxation of suture-fixated posterior chamber intraocular lenses a clinicopathologic study. Ophthalmology 2007;114(2):232-237.
We read with interest this article by Ong HS et al on “Evolution of therapies for the corneal endothelium: past, present and future approaches”.
As the article mentions, Rho kinase (ROCK) inhibitors have been described in the regenerative approach to corneal endothelial injury by aiding cell proliferation.1 Due to the wide range of cellular responses controlled by the Rho kinase signalling pathway, ROCK inhibitors play a part in increasing cell adhesion and proliferation of the corneal endothelium. Their clinical use has also been reported with success in Fuch’s endothelial dystrophy and pseudophakic corneal decompensation. 0.4% Ripasudil eye drop is the common agent used in these studies.2
Show MoreEnriching nutrients, antibiotics and other additives have been described in literature to add value to corneal preservation media. It would be interesting to see if addition a Rho kinase inhibitor to the donor corneal preservation medium could enhance the endothelial cell count or limit attrition over longer preservation times. The parameters of the drop in terms of strength, solubility, minimum concentration, side effects if any etc. need to be evaluated prior. Of all the methods described to improve the corneal endothelial health, this is the only one that may be extrapolated to donor corneal tissue also, for better surgical outcomes
It may be worthwhile to test if adding a ROCK inhibitor may enhance donor corneal tissue viability in storage media, under controlled...
Eyes with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast vision from increased glare even if high-contrast acuity is not affected.1 In a retrospective study, Augustin and colleagues suggested that corneal guttae without edema contribute to decreased contrast sensitivity, and that such eyes would benefit from Descemet membrane endothelial keratoplasty (DMEK).2 The topic is important because it is unknown whether guttae in the absence of any corneal edema affect vision and therefore whether such eyes truly benefit from DMEK. The authors enrolled eyes with >5 mm of confluent guttae and without edema (modified Krachmer grade 5); however, they did not state their definition of “edema”. In FECD, when corneal edema is not clinically detectable by slit-lamp examination, it can be detected by Scheimpflug tomography.3 A recent study found evidence of subclinical corneal edema in 88% of eyes with FECD grade 5 and almost 40% of eyes with lesser grades of FECD.4 It is therefore highly likely that many of the FECD eyes examined by Augustin and colleagues did in fact have subclinical corneal edema, so can the authors examine the Scheimpflug tomograms of these eyes and report the contrast sensitivity results based on the presence or absence of subclinical edema? This is important because reduced contrast sensitivity might be caused by subclinical edema and not simply by “guttae without edema”, and cornea surgeons should not conclude that it is appr...
Show MoreDear Editor,
We thank Svasti-Salee, Snead and Alexander [1] for their interest in our study and their comment regarding the reliability of spectral domain optical coherence tomography (SD-OCT) in differentiating a completely attached hyaloid versus complete posterior vitreous detachment (PVD).
To address the author’s question, in our post-hoc analysis, only SD-OCT was used to diagnose PVD status. A slit-lamp examination specifically assessing for PVD was not performed per protocol in the TREND study, [2] therefore data other than SD-OCT were not available for post-hoc analysis.
The accepted clinical methods to determine PVD include slit-lamp examination, dynamic ultrasonography and SD-OCT, while previous generations of OCT (time-domain OCT) potentially offered insufficient resolution and field of view. Of those methods, SD-OCT has the main advantage of being operator independent and allowing systematic, standardized evaluation in a reading center setting. The approach chosen for the analysis of the TREND dataset has been repeatedly performed in several prior studies, with similar outcome data. [3-5]
A recent study cited by the authors [6] reports that PVD status on SD-OCT did not correlate well to intraoperative findings when patients underwent vitrectomy. However, vitrectomy surgery is performed in patients with vitreomacular interface disease, where often a multi-layered posterior vitreous cortex cleaving into separate planes is found, making...
Show MoreWe thank Dr. Shukla for his interest in our article and his comments 1, 2.
In our study all consecutive cases of rhegmatogenous retinal detachment (RD) that underwent pars plana vitrectomy (PPV) were included in the study regardless of complexity, type of tear, lens or refractive status, or use of supplemental buckle in order to reduce selection bias and to allow study of various subgroups of patients. For the same reason the 13 cases with silicone oil present at the time of last follow-up were not excluded. The paper referenced by Dr. Shukla reports a retinal re-detachment rate of 13.2% after removal of silicone oil (ROSO), with many of the cases performed prior to the era of small gauge vitrectomy and wide-angle viewing systems (WAVS) 3. Encircling endolaser photocoagulation further reduces the re-detachment rate to 8.6% 4. More recent surgical techniques are likely associated with a lower retinal re-detachment rate. Nevertheless, a presumed retinal re-detachment of 13.2% following ROSO corresponds to an estimated 1.7 eyes with recurrent RD out of the 13 eyes with residual silicone oil in our series 3. This in turn corresponds to a 0.5% difference in the overall single surgery success rate (SSSR) in 312 eyes. It could therefore be safely assumed that inclusion of the small group with silicone oil at the last follow-up visit did not affect the overall success rate significantly, but reduced chances of introducing a selection bias.
In our series a supplemental...
Show MoreDear Editor,
Bonafede et al1 analyzed the change over time in hypermetropia in children from the USA with partially and fully accommodative esotropia. This study complements a previous long-term follow-up multi-center publication on 164 hypermetropic children from USA, Germany, and Israel2. The follow-up was comparable: ages 3.5-10.5 years in the previous article compared to 3-12 years in the current paper. The range of spherical equivalent refractive error in the previous paper was categorized as +1-3Diopters (D) (mild hypermetropes) and +5-8D (high hypermetropes). In contrast, the current study included also moderate hypermetropes, because it involved a group with less than +4D hypermetropes and a group of children with hypermetropia of +4D or more. Esotropia in the previous study was not present in any of the mild hypermetropes but was present in half (48%) of the high hypermetropes. Due to a decrease in hypermetropia over time beyond the age of 6 years old, mild hypermetropes in the previous study were weaned from glasses (-0.095 D/year), while the high hypermetropes remained in glasses (-0.037 D/year). Similarly, because of a mean decrease of -0.17 D/year that occurred only from age 7 to 15 years, subjects in the current study with a “smaller baseline” (i.e., mild) hypermetropia stopped wearing glasses. However, most moderate and high hypermetropes beyond the age of 12 years remained in glasses (-0.18 D/year).
In conclusion, data derived from both...
Show MoreReply
To the Editor:
Show MoreWe appreciate the comments by Wei Gui and J. Sebag about Ozsaygili Cemal’s article titled ‘The effect of posterior vitreous detachment on aflibercept response in diabetic macular oedema.’1 In our study, we used the video display mode to obtain more reliable results while evaluating the posterior vitreous detachment (PVD) status with spectral-domain optical coherence tomography (SD-OCT). In a recent clinical study comparing the PVD status with ocular ultrasonography (US) and SD-OCT in patients with diabetic macular oedema (DMO), it was reported that video display mode SD-OCT showed total agreement (100% in video display mode) with US.2 We used the video display mode in all patients instead of a single cross-sectional view and excluded patients with poor image quality. Since it was a retrospective study, we could not have the chance to perform US, but excluding these patients from the study in patients where any of the 2 independent retina specialists (CO, BK) disagreed on the PVD status draws attention as factors that increase the validity of our data. In addition, the International Vitreomacular Traction Study Group, including doctor J. Sebag, has classified the posterior vitreous-macular relationship based on OCT and has mostly replaced USG with OCT in our current clinical practice.3
All eyes in our study were examined for vitreoschisis and similar anomalous PVD using SD-OCT video display mode. As you mentioned, SD-OCT has the abili...
We read with great interest the article entitled ‘Prevalence of guttae in the graft following corneal transplantation’ by Nahum et al, published in the May 2015 issue of the British Journal of Ophthalmology [1] . The authors reported the prevalence of cornea guttata postkeratoplasty in a large population of 1116 patients to be 4%. They also found that guttae postkeratoplasty do not negatively affect the visual acuity, endothelial cell density, or graft survival during the initial two postoperative years. The content of this article is important and well put, since this is the first study to reveal the prevalence and sequelae of postkeratoplasty guttae on the corneal graft.
Based on our clinical experience and on multiple published studies, the prevalence of cornea guttata in the normal population is estimated to be higher than 4% [2]. However, the low prevalence reached by Nahum et al, is explained mainly by the preoperative screening of the donor corneas for guttae, as stated in the article. Therefore, it would be very interesting if the authors can provide an estimation of the percentage of donor corneas that are usually discarded by the guttae screening in their eye bank.
Up to our knowledge, guttae are very often not detectable using inverted light microscopy, thus guttae screening as a part of the routine examination of the donor corneas is a challenging task. There is only one study performed by Borderie et al in 2001 [3], that aimed to detect the pres...
Show MoreWe read with interest the study by Özsaygili et al. in which the authors report that the presence or absence of posterior vitreous detachment (PVD) purportedly had no influence on the efficacy of aflibercept intravitreal injections in patients with diabetic macular oedema (DMO). We question the validity of this conclusion since it is known that eyes with attached vitreous require more injections to manage exudative age-related macular degeneration than eyes with PVD.1 This is presumed to be due to interference with macular access by anti-vascular endothelial growth factor (anti-VEGF) by the posterior vitreous cortex. The same mechanism of action could be expected in eyes with DMO. Thus, there may be alternative explanations for the observed lack of an effect of PVD status on the response to aflibercept. We hypothesize that the findings are due to both the unreliable diagnosis of PVD by spectral domain optical coherence tomography (SD-OCT) alone, and the possible presence of vitreoschisis.
Previous studies have shown that SD-OCT is not a robust way to diagnose PVD, since the positive predictive value is only approximately 50%.2, 3 Rather, ultrasound is the recommended way to detect complete PVD (Figure 1).2 Did Özsaygili et al. perform ultrasound in their patients? If not, they would be unable to determine true PVD status, and the validity of their conclusion needs to be called into question.
Additionally, it is unclear from the study by Özsaygili et al. wheth...
Show MoreDear Editor,
We read with interest the post-hoc study by Waldstein and colleagues concerning the impact of posterior vitreous detachment (PVD) on the efficacy of anti-VEGF treatment in neovascular age-related macular degeneration (AMD). However, the reliability of spectral-domain optical coherence tomography (SD-OCT) in confirming PVD status, upon which the findings of this study are dependent, is questionable.[1, 2] In particular, OCT is poor at distinguishing between fully attached vitreous and complete PVD.
Hwang et al recently reported limited sensitivity of SD-OCT in detecting complete PVD when compared to clinical findings at the time of vitrectomy.[1] It was found that among patients awaiting vitrectomy, OCT diagnosis of complete PVD (based on the absence of visible posterior vitreous cortex or a premacular bursa on SD-OCT) had a positive predictive value of just 53% when compared to intra-operative findings.
PVD remains a clinical diagnosis that is based on the identification of the posterior hyaloid membrane (PHM), a diaphanous, wrinkled film observable during biomicroscopic examination. The Weiss ring which it incorporates is a more variable and less reliable confirmatory sign of PHM detachment from the optic nerve head. The visible PHM is a consistent clinical finding in patients with PVD and correlates histopathologically with a type IV collagen basement membrane which begins life attached to the retina as the internal limiting membrane.[3...
Show MoreDr. Portabella reviewed the stability of 345 consecutive cases of scleral-sutured posterior chamber IOLs retrospectively.1 In discussing sutured scleral-fixated IOLs several main points must be considered: 1) type of suture utilized; 2) length of follow-up; 3) multiple surgeons or single surgeon; 4) type of knot utilized; and 5) reoperation rate.
This paper by Portabella et al.1 involved use of Prolene (polypropylene) or Mersilene sutures, follow-up with a maximum of 10 years, multiple surgeons, a knot with a single loop through the sclera and around the haptic, and a reoperation rate of 7.2%. The Vote et al study2 reviewed 61 eyes with Prolene sutures, follow-up with a maximum of 10.6 years, multiple surgeons, variable knots, and an extremely high rate of redislocation of 26.2%, which they postulated was due to suture breakage. This high rate of redislocation has not been confirmed in any other study.3,4
A recent study by Kokame et al3 involved 118 eyes utilizing 10-0 Prolene sutures, a single surgeon, follow-up of up to 24.75 years, a knot with two sutures - one secured to the haptic by a cow-hitch and the other to the sclera with both sutures tied together in a single knot under a scleral flap, and a broken suture rate of 0.5% (1/214 fixation sutures). The maximum follow-up of 24.75 years with stable fixation strongly supports the stability of 10-0 Prolene. Higher rates of redislocations of sutured scleral-fixated IOLs can be due to multiple surgeo...
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