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Recent eLetters

Displaying 1-10 letters out of 546 published

  1. Response to: Computer-aided design and three-dimensional printing in the manufacturing of an ocular prosthesis

    With interest we have read the article of Ruiters et al.1 in which they present a 3 dimensional method for ocular prosthesis manufacturing. In our practice we also manufacture individual customized ocular prosthesis using 3D techniques. We confirm that this computer aided method improves prosthetic fitting and may aid the production process when translated into 3D prints. Our method does however differ on several points. First, in contrast to the authors, we make use of a mould, second we use MRI instead of cone beam CT. We agree with Ruiters et al.1 that the method of impression-moulding without other assistance frequently results in poor fitting prostheses. However, when assisted with 3D imaging a concise delineation of the socket can be made. The impression reflects the lines and curves of the posterior part of the socket in its most natural shape since it is introduced in a liquid state. The thickness of the mould depends on the amount of used silicone, hence it is not an adequate measure to use one-on-one for the thickness of the prosthesis. We believe this mistake is frequently made and may be the cause of bad fitting prostheses. We reject the argument of Ruiters et al.1 that introduction of moulding materials cause distortion of the socket, in fact we have experienced that a conformer, as used by the authors, does result in a distortion of the socket : when delineating the socket visualized on 3D images with a solid conformer in situ the delineation follows exactly the contours of the conformer. We use a special MRI program for orbital scanning taking only 5 - 6 minutes. In patients younger than 7 years scanning can be performed with general anesthesia, older patients can be instructed to lay still, head fixation eliminates motion artefacts as is also mentioned by Ruiters et al.1 MRI imaging avoids exposure to radiation, and MR- images will better depict the orbital soft tissues. In an upcoming paper we will expound our method.

    1. Computer-aided design and three-dimensional printing in the manufacturing of an ocular prosthesis. S?bastien Ruiters, Yi Sun, St?phan de Jong, Constantinus Politis, Ilse Mombaerts. Br J Ophthalmol 2016;100:7 879-881

    Conflict of Interest:

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  2. Anatomical effects of dexamethasone intravitreal implant in diabetic macular oedema: a pooled analysis of 3-year phase lll trials

    Anatomical effects of dexamethasone intravitreal implant in diabetic macular oedema; a pooled analysis of 3-year phase lll trials Dan Calugaru, Mihai Calugaru Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania Re: Anatomical effects of dexamethasone intravitreal implant in diabetic macular oedema: a pooled analysis of 3-year phase lll trials. Danis et al Br J Ophthalmol 2016;100:796-801.

    Dear Editor We would like to address several challenges arisen from the study by Danis et al (1) and which can be specifically summarized as follows:

    1. There was a selection bias owing to the inclusion in the study of both the treatment-na?ve patients and those with previous treatments (focal/grid laser, intravitreal steroid, and specific anti-vascular endothelial growth factor [VEGF] agents).

    2. Although the final central subfield retinal thickness (CSRT) values of the two dexamethasone implant (DEX implant; Ozurdex Allergan, Irvine, California, USA) groups (eg, 345.7 and 339 microns in the DEX implant 0.7 mg and DEX implant 0.35 mg groups, respectively) were significantly reduced in comparison with the sham group (398.8 microns) yet the structural outcomes of this study were poor. Of note, all these CSRT values are much more than the cutoff (252 microns) for the upper level of the normal CSRT (212 +/-20 microns) plus 2 standard deviations (2). The persistence of high values of the CSRT as well as the high proportions of study eyes with CSRT > 250 microns at the final visit (eg, 60.2 %, 58.7%, and 71.6% in the DEX implant 0.7 mg, DEX implant 0.35 mg, and sham groups, respectively) highlight unresolved macular edema due to insufficient macular deturgescence and indicate that the disease process is still active and progressive requiring further treatment with anti-angiogenic agents.

    3. The final unsatisfactory anatomic results of this study could be explained by the low frequency of injections (a median of four to five injections over a 3-year period) and the long-standing duration of diabetic macular oedema (DME) (between 23.6 and 25.9 months in the three groups of patients). These facts promoted the delayed occurrence of a permanent retinal capillaropathy owing to permanent breakdown of the inner and outer endothelial blood-retinal barriers. However, this condition is incurable due to the ischemic irreversible lesions to the macular retinal ganglion cell complex, close to the foveola, with macular oedema being a minor factor. The saw-tooth pattern of the profile of mean change in CSRT versus time highlights the fact that the authors have not taken into account the currently valid recommendations that the duration of ? 3-line improvement after DEX implant is typically 2-3 months (3), and that reinjections generally will be performed after 4-5 months (4). If these assertions had been considered, the design and outcomes of the present study would have been completely different.

    Altogether, regardless of the intravitreal pharmacotherapy chosen, namely, specific or nonspecific (DEX implant) anti-VEGF agents, the efficacy of treatment depends primarily on the promptness of the therapy after DME onset. Both groups of anti-VEGF substances provide similar rates of vision improvement but with superior anatomic outcomes and fewer injections in the DEX implant-treated eyes. However, more patients receiving the DEX implant lose vision mainly due to cataract.

    References 1. Danis RP, Sadda S, Li XY, et al. Anatomical effects of dexamethasone intravitreal implant in diabetic macular oedema: a pooled analysis of 3- year phase lll trials. Br J Ophthalmol 2016; 100:796-801. 2. Chan A, Duker JS, Ko TH, et al. Normal macular thickness measurements in healthy eyes using Stratus optical coherence tomography. Arch Ophthalmol 2006;124;193-198. 3. Kuppermann BD, Haller JA, Bandello F. Onset and duration of visual acuity improvement after dexamethasone intravitreal implant in eyes with macular edema due to retinal vein occlusion. Retina 2014;34:1743-1749. 4. Coscas G, Augustin A, Bandello F, et al. Retreatment with Ozurdex for macular edema secondary to retinal vein occlusion. Eur J Ophthalmol 2014;24:1-9.

    Conflict of interest: None declared

    Conflict of Interest:

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  3. Re:Comment on: Morphological features in anterior scleral inflammation using swept-source optical coherence tomography with multiple B-scan averaging

    Dear Editor:

    We thank Dr. Ebneter for his interest in our article.1 He pointed out that we included contralateral eyes of unilateral diseased eyes as control eyes and both eyes of bilateral affected eyes were included as diseased eyes. Accordingly, we performed additional analyses. We excluded contralateral eyes from control eyes and included only right eyes of bilateral affected eyes as diseased eyes. As a result, the average thicknesses of conjunctival epithelium, conjunctival stroma/episclera complex, and scleral stroma were 55.4?8.8, 288.0?44.4, and 434.2?60.1 ?m in the control group, 52.2?8.8, 320.7?48.6, and 455.8?43.4 ?m in diffuse episcleritis, 79.6?28.8, 450.7?138.3, and 469.5?41.7 ?m in diffuse scleritis, respectively. Significant differences could be found in conjunctival epithelium and conjunctival stroma/episclera complex among the three groups (p=0.002, 0.001, Kruskal-Wallis test), but not in scleral stroma (p=0.231). In diffuse scleritis, conjunctival epithelium and conjunctival stroma/episclera complex were significantly thicker than in controls (p=0.013 and 0.002). These results showed the same tendency as the original results.

    Second, Dr. Ebneter pointed out the weakness of the method, which is that the thickness is measured vertically but not perpendicularly to the ocular surface. We agree with him that this measurement method was crude and moderately inaccurate. Unfortunately, we could not measure the thickness in a direction perpendicular to conjunctival epithelium because SS-OCT was used for the posterior segment. Moreover, he indicated that the borders of the sclera in Figure 2B and 4B were vague. Indeed, it may not be easy to clearly distinguish scleral stroma and episclera. Severe thickening in the conjunctival stroma and episcleral layer may make the border indistinct. However, the point of this article, which is that thickening occurred mainly in the episclera rather than in the scleral stroma in diffuse scleritis, was meaningful, even if the measurements were crude.

    References

    1. Kuroda Y, Uji A, Morooka S, et al. Morphological features in anterior scleral inflammation using swept-source optical coherence tomography with multiple B-scan averaging. Br J Ophthalmol 2016. doi: 10.1136/bjophthalmol-2016-308561.

    Conflict of Interest:

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  4. Changing from pro re nata treatment regimen to a treat and extend regimen with ranibizumab in neovascular age-related macular degeneration

    Changing from pro re nata treatment regimen to a treat and extend regimen with ranibizumab in neovascular age-related macular degeneration Dan Calugaru, Mihai Calugaru Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania

    Re: Changing from pro re nata treatment regimen to a treat and extend regimen with ranibizumab in neovascular age-related macular degeneration. Hatz and Prunte. Br J Ophthalmol 2016; http:/dx. doi.org/10.1136/bjophthalmol-2015-307299.

    Dear Editor We would like to address several limitations arisen from the interesting study by Hatz and Prunte (1) and which can be specifically summarized as follows:

    1. The article was retrospectively conducted with the existence of a selection bias due to the inclusion in the final analysis only those patients who completed treat and extend (TE) follow-up of 12 months. Of note, only patients with active disease during the last 3 months of the pro re nata (PRN) phase were transitioned to TE treatment.

    2. With the exception of data concerning the baseline choroidal neovascularization (CNV), there were no details on the anatomical types of neovascular maculopathy (CNV/serous and/or hemorrhagic detachment of the neurosensory retina or retinal pigment epithlium [RPE]/retinal hard exudates/subretinal and sub-RPE fibrovascular proliferation/disciform scar [subretinal fibrosis]), at baseline visit, as well as before and after switching from a PRN to a TE treatment regimen.

    3. There were no data referring to the proportion of eyes considered "dry" on optical coherence tomography as per criterion of central retinal thickness (CRT) < 320 microns (2), before and after switching to a TE algorithm.

    4. The comparative analysis of the visual and morphologic outcomes of the two treatment regimens was fairly inconclusive. Thus, there was a mean visual acuity (VA) gain of approximately 5 Early Treatment Diabetic Retinopathy Study (ETDRS) letters in comparison with the baseline VA at the end of the PRN phase; this value increased subsequently by an average of approximately 5 letters until the month 12 of the TE phase. The CRT decreased by a mean of 86 microns in relation to the baseline value, up to the end of the PRN phase; this CRT reduction increased thereafter by a mean of 35 microns until the month 12 of the TE phase. Importantly, during the TE period of this study, patients received approximately two more injections over a 12-month period than during 12 months of PRN treatment.

    5. Implementation of the 2-sequence, 2-period, 2-treatment algorithm design in which each patient was assigned to a sequence of treatment, did not provide the answer to the question which of the 2 treatment approaches was more efficiently. On the contrary, the disadvantages of such a study could not be avoided. Thus, the washout period, which is essential between periods of such a study in terms of aliased effects, was not precisely delimited and the impact of the significant carryover effects may be confounded with direct treatment effects, in the sense that these effects could not be estimated separately being able to bias the interpretation of data analysis.

    Altogether, regardless of the treatment approaches chosen (TE/PRN algorithm), the efficacy of therapy depends primarily on the promptness of the therapy after neovascular age-related degeneration diagnosis (3,4).

    References 1. Hatz K, Prunte C. Changing from pro re nata treatment regimen to a treat and extend regimen with ranibizumab in neovascular age-related degeneration. Br J Ophthalmol 2016; http:/dx. doi.org/10.1136/bjophthalmol -2015-307299. 2. Grover S, Murthy RK, Brar VS, and Chalam KV. Normative data for macular thickness by high-definition spectral-domain optical coherence tomography (spectralis). Arch Ophthalmol 2009;148-271. 3. Calugaru D, Calugaru M. Treat-and-extend intravitreal bevacizumab for branch retinal vein occlusion. Ophthalmic Surg Lasers Imaging Retina 2015;46:994. 4. Calugaru D, Calugaru M. Comment on:"Central retinal vein occlusion:modyfing current treatment protocols." Eye 2016; http:/dx.doi.org/10.1038/eye.2016.83.

    Conflict of interest: None declared

    Conflict of Interest:

    None declared

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  5. Re:Outcomes of intravitreal anti-VEGF therapy in eyes with both neovascular age-related macular degeneration and diabetic retinopathy

    We thank Drs Calugaru M. and Calugaru D. for their interest in our article,1 and we welcome this opportunity to address their concerns. The purpose of our study was to investigate the outcomes of intravitreal antivascular endothelial growth factor (VEGF) therapy in eyes with both neovascular age-related macular degeneration (AMD) and diabetic retinopathy (DR) as higher levels of VEGF due to concomitant DR in eyes with active neovascular AMD may lead to a higher consumption of anti-VEGF molecules, thus impairing the efficacy of treatment.1 As pointed out, in our series we included patients that had undergone other treatments for DR, either before or during administration of anti- VEGF drugs for neovascular AMD. This is an obvious limitation of our retrospective study, even though all the patients included were treatment na?ve for anti-VEGF agents. We recorded that best corrected visual acuity, after a significant improvement at 1 year, returned to baseline values at the last follow-up visit, while mean central macular thickness (CMT) significantly decreased from 408 ?m to 335 ?m. As pointed out, these results may suggest that disease process could be still active and progressive requiring further treatment. 2 In fact, at the end of follow up, CNV was still active in 39% eyes, while 61% eyes developed an atrophic/fibrotic scar with no signs of activities. On the other hand, CMT could have been influenced by the two concomitant diseases, the diabetic retinopathy and the choroidal neovascularization. In particular, we cannot exclude that some patients underwent anti-VEGF treatment, DR-related macular edema. We agree that, a lot of cytokines, chemokines, and growth factors may be associated with DR pathophysiology.3,4 Further prospective studies should consider the effects of these molecules and the use of non-specific anti- VEGF substances which inhibits the up-regulation of the VEGF and suppresses the expression of the whole panoply of the proinflammatory and proangiogenic factors.

    References 1. Bandello F, Corvi F, La Spina C, et al. Outcomes of intravitreal anti- VEGF therapy in eyes with both neovascular age-related macular degeneration and diabetic retinopathy. Br J Ophthalmol 2016; http:/dx.doi.org/10.1136/bjophthalmol-2016- 308400. 2. Gover S, Murthy RK, Brar VS, et al. Normative data for macular thickness by high-definition spectral-domain optical coherence tomography (spectralis). Am J Ophthalmol 2009;148:266-271. 3. Sohn HJ, Han DH, Kim IT, et al. Changes in aqueous concentrations of various cytokines after intravitreal triamcinolone versus bevacizumab for diabetic macular edema. Am J Ophthalmol 2011;152:686-694. 4. Shah SU, Harless A, Bleau L, et al. Prospective randomized subject- masked study of intravitreal bevacizumab monotherapy versus dexamethasone implant monotherapy in the treatment of persistent diabetic macular edema. Retina. 2016 Apr 27. [Epub ahead of print]

    Conflict of Interest:

    None declared

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  6. Outcomes of intravitreal anti-VEGF therapy in eyes with both neovascular age-related macular degeneration and diabetic retinopathy

    Outcomes of intravitreal anti-VEGF therapy in eyes with both neovascular age-related macular degeneration and diabetic retinopathy Dan Calugaru, Mihai Calugaru Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania

    Re: Outcomes of intravitreal anti-VEGF therapy in eyes with both neovascular age-related macular degeneration and diabetic retinopathy. Bandello et al. Br J Ophthalmol 2016; http:+/dx. doi.org/10.1136/bjophthalmol-2015-308400.

    Dear Editor We would like to address several challenges arisen from the interesting study by Bandello et al [1] and which can be summarized specifically as follows:

    1. The article was retrospectively conducted with the existence of a selection bias due to previous treatments applied for diabetic retinopathy (DR) in 12% of the patients (eg., paretinal photocoagulation [PRP] in 5% and grid laser in 7% of the patients). Moreover, there were other treatments than those with the antivascular endothelial growth factor (VEGF) agents which were administered during follow-up (eg., dexamethasone implant in 12%, PRP in 2%, photodynamic therapy in 15%, and stereotactic radio in 2% of the eyes).

    2. We analyzed the results of this study taking into account the current assertion whereby the assessment should be guided by anatomical measure data with visual changes as a secondary guide [2]. Thus, best corrected visual acuity improved significantly at 1 year but returned to baseline values at the end of the follow-up, while mean central macular thickness (CMT) significantly decreased from 408 to 335 microns at last follow-up visit. Of note, this CMT value is more than the cutoff (315.2 microns) for the upper level of normal foveal thickness (270+/- 22.5) [3] plus 2 standard deviations and highlights unresolved macular edema indicating that the disease process is still active and progressive requiring further treatment.

    3. The final anatomic results in eyes with both neovascular age- related macular degeneration (AMD) and DR were poor. They revealed 39% of the eyes with active choroidal neovascularization, 22% with predominantly atrophic scar, and 39% of the eyes with predominantly fibrotic scar. Additionally, one eye graded as severe non-proliferative DR progressed to proliferative DR and finally was inactivated due to PRP.

    4. The results of this series can be explained by the low frequency of injections (a mean of 9.2) as well as the long duration of diabetes (a mean of 22 years). Most likely there was a chronic retinal capillaropathy due to permanent breakdown of the inner and outer blood-retinal barriers following ischemic changes to the macular ganglion cell complex, close to the foveola.

    Altogether, the specific anti-VEGF agents represent the front-line therapy for AMD and DR. Because o lot of cytokines, chemokines, and growth factors may be associated with DR pathophysiology [4,5], the addition of a non-specific anti-VEGF substance, eg., a corticosteroid implant, which inhibits the up-regulation of the VEGF and suppresses the expression of the whole panoply of the proinflammatory and proangiogenic factors, is mandatory.

    References 1. Bandello F, Corvi F, La Spina C, et al. Outcomes of intravitreal anti- VEGF therapy in eyes with both neovascular age-related macular degeneration and diabetic retinopathy. Br J Ophthalmol 2016; http:/dx.doi.org/10.1136/bjophthalmol-2016-308400. 2. Freund KB, Korobelnik JF, Deveny R, et al. Treat-and-extend regimens with anti-VEGF agents in retinal diseases. A literature review and consensus recommendations. Retina 2015;35:1489-1506. 3. Gover S, Murthy RK, Brar VS, et al. Normative data for macular thickness by high-definition spectral-domain optical coherence tomography (spectralis). Am J Ophthalmol 2009;148:266-271. 4. Sohn HJ, Han DH, Kim IT, et al. Changes in aqueous concentrations of various cytokines after

    intravitreal triamcinolone versus bevacizumab for diabetic macular edema. Am J Ophthalmol

    2011;152:686-694. 5. Shah SU, Harless A, Bleau L, et al. Prospective randomized subject- masked study of

    intravitreal bevacizumab monotherapy versus dexamethasone implant monotherapy in the

    treatment of persistent diabetic macular edema. Retina 2016;http:/dx.doi.org/10.1097/IAE

    0000000000001038.

    Conflict of interest: None declared

    Conflict of Interest:

    None declared

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  7. Comment on: Risk factors for low vision related functioning in the Mycotic Ulcer Treatment Trial: a randomised trial comparing natamycin with voriconazole

    eLetter Comment on: Risk factors for low vision related functioning in the Mycotic Ulcer Treatment Trial: a randomised trial comparing natamycin with voriconazole Parul Chawla Gupta, MS; Jagat Ram, MS, FAMS Department of Ophthalmology Post Graduate Institute of Medical Education and Research, Chandigarh, India, 160012 Corresponding author Dr. Jagat Ram, MS, FAMS Professor and Head Department of Ophthalmology Post Graduate Institute of Medical Education and Research, Chandigarh, India, 160012 Email id: drjagatram@gmail.com Conflict of interest and source of funding- None declared

    Dear Editor, We read with interest the recent paper by Rose- Nussbaumer and associates [1] determining the risk factors for low vision-related quality of life in patients with fungal keratitis. While the study is indeed interesting, we herein address important issues, some of which warrant further discussion. First, the authors stated in the abstract "Those who required therapeutic penetrating keratoplasty had an average of 25.2 points decrease on VFQ after correcting for treatment arm (95% CI ?31.8 to ?18.5, p<0.001).". However, in the manuscript it is mentioned that "study participants who required therapeutic penetrating keratoplasty (TPK) had significantly worse VFQ scores than those who did not, with those having undergone TPK scoring on average 25.5 points lower on VFQ (95% CI ?32.0 to ?18.9, p<0.001)." Second, since marital status is one of the robust predictor of health outcomes, it should have been taken into account as it may affect the quality of life in the study patients. It has been seen that divorced and widowed men report higher rates of depressive symptoms than married men [2]. Third, presence of other comorbidities like diabetes, cancer, organic disorders/cognitive impairment or current use of any medication due to a psychiatric disorder eg. antidepressants should be ruled out. Moreover, use of topical nonselective beta-blockers or intake of oral lipophilic beta blockers for hypertensives should also be considered since they may lead to depression [3, 4] and subsequently affect quality of life. References 1. Rose- Nussbaumer J, Prajna NV, Krishnan T, et al. Br J Ophthalmol 2016;100:929-932. 2. Jang SN, Kawachi I, Chang J et al. Marital status, gender, and depression: Analysis of the baseline survey of the Korean Longitudinal Study of Ageing (KLoSA). Soc Sci Med 2009; 11(12): 1608-15. 3. Verbeek DE, van Riezen J, de Boer RA, van Melle JP, de Jonge P. A review on the putative association between beta-blockers and depression. Heart Fail Clin. 2011;7(1):89-99. 4. Augustin A, Sahel JA, Bandello F et al. Anxiety and depression prevalence rates in age-related macular degeneration. Invest Ophthalmol Vis Sci. 2007;48(4):1498-503.

    Conflict of Interest:

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  8. Comment on: The impact of donor age and endothelial cell density on graft survival following penetrating keratoplasty

    eLetter Comment on: The impact of donor age and endothelial cell density on graft survival following penetrating keratoplasty Parul Chawla Gupta, MS; Jagat Ram, MS, FAMS Department of Ophthalmology Post Graduate Institute of Medical Education and Research, Chandigarh, India, 160012 Corresponding author Dr. Jagat Ram, MS, FAMS Professor and Head Department of Ophthalmology Post Graduate Institute of Medical Education and Research, Chandigarh, India, 160012 Email id: drjagatram@gmail.com Conflict of interest and source of funding- None declared

    Dear Editor, We read with interest the recent paper by Wakefield and associates [1] analysing if donor age and preoperative endothelial cell density (ECD) affects corneal endothelial failure following penetrating keratoplasty (PK). While the study is indeed interesting, we herein address important issues, some of which warrant further discussion. First, the authors have determined the overall 5-year graft survival rate due to endothelial failure in all recipients. No mention has been made of the endothelial cell density/loss at 5 years after surgery in all age groups. Was there any significant difference in the endothelial cell density in all groups? Second, diabetic status has been few of the factors affecting corneal endothelial cell counts. In patients with diabetes (after adjusting age), the cell count is lesser by 66 cells (95% CI, 6.3-125.9) compared with controls [2]. Did the authors take into consideration the presence or absence of diabetes mellitus in all groups since higher prevalence of diabetes in the younger age group donors could have decreased the graft survival ultimately making it comparable with the graft survival of corneas from elderly donors. Third, cigarette smoking reduces endothelial cell counts [3]. Smoking history should also have been considered while comparing the graft survival rates in all the groups. Moreover, advanced nuclear cataract and chronic pulmonary disease are significant risk factors for reduced endothelial density. Although the mechanisms are unknown, patients with these risk factors may have a poor endothelial reserve [4]. The authors should therefore rule out all the aforementioned factors before analyzing the results. References 1. Wakefield MJ, Armitage WJ, Jones MNA, et al. Br J Ophthalmol 2016;100:986-989. 2. Sudhir RR, Raman R, Sharma T. Changes in the Corneal Endothelial Cell Density and Morphology in Patients With Type 2 Diabetes Mellitus: a Population Based Study, Sankara Nethralaya Diabetic Retinopathy And Molecular Genetics Study (SN-DREAMS, Report 23). Cornea 2012; 0:1-4. 3. Ilhan N, Ilhan O, Coskun M, et al. Effects of Smoking on Central Corneal Thickness and the Corneal Endothelial Cell Layer in Otherwise Healthy Subjects. Eye Contact Lens. 2015; 10.1097/ICL.0000000000000212 4. Ishikawa A. Risk factors for reduced corneal endothelial cell density before cataract surgery. J Cataract Refract Surg. 2002;28(11):1982-92.

    Conflict of Interest:

    None declared

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  9. Intravitreal bevacizumab for diabetic macular edema: 5-year results of the Pan-American collaborative retina study group

    Intravitreal bevacizumab for diabetic macular oedema: 5-year results of the Pan-American collaborative retina study group. Dan Calugaru, Mihai Calugaru Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania

    Re: Intravitreal bevacizamab for diabetic macular oedema: 5-year results of the Pan-American collaborative retina study group. Arevalo et al. Br J Ophthalmol published online on February 24, 2016;doi:10.1136/bjophthalmol-2015-307950.

    Dear Editor The article by Arevalo et al [1] has several shortcomings that prevent the validation and extrapolation of their results and that can be specifically summarized as follows:

    1. The study was retrospectively conducted with the existence of a selection bias due to the lack of a uniform clear treatment schedule for injections and reinjections, the decision to treat being left at the discretion of the treating physicians. Additionally, a total of 113 eyes were diagnosed with proliferative diabetic retinopathy and treated with panretinal photocoagulation at least 6 months before undergoing intravitreal bevacizumab (IVB) for diabetic macular oedema (DME).

    2. The assessment of the final outcomes should be made taking into account the current assertion whereby evaluation of the outcomes has to be guided by the anatomical measure data with the visual changes as a secondary guide [2]. Accordingly, the visual and anatomic improvements of this study were poor. Thus, while early visual gains due to IVB were not maintained 5 years after treatment, the central macular thickness (CMT) decreased significantly from 403.5 to 313.7 microns over 5 years follow- up. Importantly, this value is much more than the cutoff (252 microns) for the upper level of normal foveal thickness (212 ? 20 ?m)(3) plus 2 standard deviations. Of note, the proportion of eyes considered "dry" on optical coherence tomography as per criterion of foveal thickness ? 260 ?m was 29.4%, the rest of the eyes having unresolved macular oedema.

    3. The results of this study could be explained by the low frequency of injections (a mean of 8.4 IVB injections per eye over 5 years) as well as the long duration of diabetes (a mean of 15.8 years). Most likely there was a chronic retinal capillaropathy due to permanent irreversible breakdown of the inner and outer blood retinal barriers. The vascular endothelial growth factor (VEGF) is one proven contributor to macular oedema in diabetic retinopathy. Besides, a panoply of proinflammatory and proangiogenic cytokines, chemokines, and growth factors may be associated with pathophysiology of DME [4,5].

    Altogether, the specific anti-VEGF drugs represent the front-line therapy for the treatment of DME but VEGF inhibition only may not be sufficient to decrease inflammatory response. Therefore, addition of a non -specific anti-VEGF substance, i.e., intravitreal steroid injection is mandatory. Otherwise, patients will be impeded to achieve maximal visual and anatomic benefits. References 1. Arevalo JF, Lasave AF, Wu L, et al. Intravitreal bevacizumab for diabetic macular oedema: 5-year results of the Pan American collaborative retina study group. Br J Ophthalmol 2016, online first published on February 24, 2016; doi:10.1136/bjophthalmol-2015-307950. 2. Freund KB, Korobelnik JF, Deveny R, et al. Treat-and-extend regimens with anti-VEGF agents in retinal diseases. A literature review and consensus recommendations. Retina 2015;35:1489-1506. 3. Chan A, Duker JS, Ko TH, et al. Normal macular thickness measurements in healthy eyes using optical coherence tomography. Arch Ophthalmol 2006;124:193-198. 4. Sohn HJ, Han DH, Kim IT, et al. Changes in aqueous concentrations of various cytokines after intravitreal triamcinolone versus bevacizumab for diabetic macular edema. Am J Ophthalmol2011;152:686-694. 5. Shah SU, Harless A, Bleau L, et al. Prospective randomized subject- masked study of intravitreal bevacizumab monotherapy versus dexamethasone implant monotherapy in the treatment of persistent diabetic macular edema. Retina 2016, online first published on April 27, 2016; doi:10.1097/IAE 0000000000001038.

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  10. Comment on: Morphological features in anterior scleral inflammation using swept-source optical coherence tomography with multiple B-scan averaging.

    Dear Editor,

    I read with interest the article by Kuroda et al.[1] The authors explored new possibilities of anterior segment imaging using a posterior segment swept-source optical coherence tomography device without noteworthy modifications. Interestingly, it was possible to obtain high- resolution images of the conjunctiva, episclera, and the sclera near the limbus that seemingly allow unequivocal identification of anatomical boundaries. The authors used this technique to examine eyes with anterior scleritis/episcleritis.

    However, I was not so impressed when I read through the methods section of the paper. Contralateral eyes of patients were included as controls. This is certainly problematic, considering that some of the subjects had systemic inflammatory disease. In patients with overt bilateral disease, both eyes were included in the analysis. As a result, the measurements are not independent,[2] and the use of basic statistical tests such as the Mann-Whitney or Kruskal-Wallis tests is not legitimate. All these tests require independence of observations. Advanced statistical methods[3] such as generalized estimating equations[4] or paired comparison[5] would be necessary to obtain statistically valid results.

    Another significant weakness of the methodology is that the thickness of tissues was not measured perpendicularly to the ocular surface. This makes data prone to bias and increases the variability. Moreover, the internal limits of the sclera in Figures 2B and 4B are not very distinct, and one wonders how accurate the measurements of this boundary are in other eyes in the study, if these photos are representative.

    To sum up, the images displayed are promising, yet, the scientific rigour of the paper is much less compelling.

    References

    1. Kuroda Y, Uji A, Morooka S, et al. Morphological features in anterior scleral inflammation using swept-source optical coherence tomography with multiple B-scan averaging. Br J Ophthalmol Published Online First: 7 July 2016. doi: 10.1136/bjophthalmol-2016-308561

    2. Ray WA, O'Day DM. Statistical analysis of multi-eye data in ophthalmic research. Invest Ophthalmol Vis Sci 1985; 26:1186-8.

    3. Fan Q, Teo YY, Saw SM. Application of advanced statistics in ophthalmology. Invest Ophthalmol Vis Sci 2011; 52:6059-65.

    4. Hanley JA, Negassa A, Edwardes MD, et al. Statistical analysis of correlated data using generalized estimating equations: an orientation. Am J Epidemiol 2003; 157:364-75.

    5. Murdoch IE, Morris SS, Cousens SN. People and eyes: statistical approaches in ophthalmology. Br J Ophthalmol 1998; 82:971-3.

    Conflict of Interest:

    None declared

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