eLetters

685 e-Letters

  • Response to Svasti-Salee, Snead and Alexander

    Dear 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 More
  • Authors Response to Dr. Dhananjay Shukla's Correspondence

    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...

    Show More
  • Will children with hypermetropia still need glasses when they grow older?

    Dear 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 More
  • Reply to: The Effect of Posterior Vitreous Detachment on Aflibercept Response in Diabetic Macular Oedema

    Reply

    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...

    Show More
  • Preoperative guttae screening of the donor corneas

    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 More
  • Re: Özsaygili et al.: The effect of posterior vitreous detachment on aflibercept response in diabetic macular oedema

    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...

    Show More
  • Response to 'Effect of posterior vitreous detachment on treat-and-extend versus monthly ranibizumab for neovascular age-related macular degeneration

    Dear 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 More
  • Long Term Stability of Sutured Scleral-fixated Intraocular Lenses

    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...

    Show More
  • No vitreous base shaving: one size does not fit all

    Tabandeh and colleagues[1] presented a contrarian viewpoint on the redundancy of scleral-depressed vitreous base shaving: a procedure we have come to take for granted during vitrectomy for retinal detachment (RD). Their excellent outcomes are great news for trainee surgeons, as lens touch is likely during meticulous base dissection in phakic eyes. Sutureless micro-incision vitreous surgery is indeed more secure with residual peripheral vitreous, which plugs the sclerotomy leaks. The authors’ attribution of their high success rate to circumferential laser photocoagulation is validated by a randomized clinical trial.[2] The cases with residual silicone oil (13/89; 15%) should however not be included in the anatomical success; a significant percentage of them re-detach after oil removal.[3]
    The optional use of scleral buckle in this study is confusing. The authors have not specified the choice of buckle (most probably an encircling belt-buckle). Vitreous base-shaving is critical to anatomical success when no encirclage is used.[3] The authors reported no additional benefit from buckling, though it was preferentially performed for complex detachments. 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. A recent study suggested that anterior dissection is essential in the presence of posteriorly inserted vitreous base.[4] Did the authors observe this vitreous config...

    Show More
  • COVID-19 and immunosuppression in ophthalmic disorders

    The review article by Thng ZX, De Smet MD, Lee CS, et al 1highlights the most intriguing aspects on use of immunosuppressants during and post COVID-19 pandemic. The authors have presented evidences based on various reports in a very well-structured manner and we would like to first thank and congratulate the authors for their work. The review covers the wide range of faculties of medicine where immune suppression is likely to be the main stay of treatment. At the same time, they have also very neatly presented with the “clear cut “ guidelines on the dosing of these various medications at different scenarios and patient status.

    While the article additionally covers the following aspects very well ;

    1) Does the use of immunosuppressive present as an independent risk factor for contracting COVID -19 in patients under them?
    2) Does it affect the severity of COVID -19 ?

    We have few inquiries to make to the authors regarding the use of immunosuppressive in ophthalmology during this difficult time.

    The authors have used the term “high dose steroids” in their article. Firstly, we are curious to understand what would be the considered the criteria to define a “high dosage” of steroid in ophthalmology. From our understanding, it depends upon the class of steroid used and the body weight2 but should we also need to consider the duration of use and cumulative dosage over a stretch of time to define it?

    Also, referring to various public...

    Show More

Pages