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Recent eLetters

Displaying 1-10 letters out of 554 published

  1. Re:re: Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients

    Response to: Role of Case Series Studies in the Identification of Anaesthetic Complications Dear Editor, We would like to acknowledge Eke and Kumar for their comments on our article.1 In our retrospective case series study of 12,992 patients, we noted that subtenon anaesthesia had more complications and that both topical and subtenon anaesthesia in our series were the ideal anaesthetics.

    Retrospective case series studies still play an important role in the progress of medical science2 with aims that complement other research designs in the pursuit of evidence.3 Shyam et al further noted that case series studies are well placed at the apex of hypothesis generation and play a role in the identification of side effects and complications4 as similarly intended in our study. Further, other case series studies5,6 and a systematic review of case series7 have sought to analyze the association of side effects and complications with surgical treatment and procedures.

    Almost all cases of phacoemulsification were conducted under topical anaesthesia in our set-up. This included cases where difficulties were anticipated such as pseudoexfoliation, small pupils and dense cataracts. The switch to topical was made in recent years once the surgeons were comfortable and convinced that topical anaesthesia works well without complications of injections and patients were happy with the white eye appearance. A recent Cochrane review on the topic noted that "all trials were performed at a time when surgeons were only starting to use topical anesthesia".8 In light of this, we look forward to further research as surgeons become more proficient in their use of topical anesthesia.

    References

    1. Thevi T, Godinho MA. Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients. Br J Ophthalmol 2016;100:1708-1713.

    2. Vandenbroucke JP. Case reports in an evidence-based world. J R Soc Med. 1999;92:159-63.

    3. Vandenbroucke JP. In defense of case reports and case series. Ann Intern Med 2001;134(4):330-4.

    4. Shyam A, Shetty G. Case Reports and Evidence Based Medicine: Redefining the Apex of the Triangle. J Orthop Case Rep 2012;2(2):1-2.

    5. Saito Y1, Uraoka T, Matsuda T, Emura F, Ikehara H, Mashimo Y, Kikuchi T, Fu KI, Sano Y, Saito D. Endoscopic treatment of large superficial colorectal tumors: a case series of 200 endoscopic submucosal dissections (with video). Gastrointest Endosc 2007;66(5):966-73.

    6. Sowash M, Barzilai O, Kahn S, McLaughlin L, Boland P, Bilsky MH, Laufer I. Clinical outcomes following resection of giant spinal schwannomas: a case series of 32 patients. J Neurosurg Spine. 2017;13:1-7. doi: 10.3171/2016.9.SPINE16778.

    7. Hasimoto CN, Cataneo C, Eldib R, Thomazi R, Pereira RS, Minossi JG, Cataneo AJ. Efficacy of surgical versus conservative treatment in esophageal perforation: a systematic review of case series studies. Acta Cir Bras 2013;28(4):266-71.

    8. Guay J, Sales K. Sub-Tenon's anaesthesia versus topical anaesthesia for cataract surgery. Cochrane Database of Systematic Reviews 2015; Issue 8. Art. No.: CD006291. DOI: 10.1002/14651858.CD006291.pub3.

    Conflict of Interest:

    None declared

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  2. re: Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients

    Editor,

    We read Thevi and Godhino's article (1) with interest, but we feel that the methodology does not support their conclusions. They aimed to 'find out the most suitable anaesthesia for patients with fewer complications' in cataract surgery, and reported that 'sub-Tenon anaesthesia [STA] was associated with more intraoperative and postoperative complications ... topical anaesthesia [TA] ... is the ideal anaesthesia'(1). However, this was a retrospective observational case- series, not a randomised study. Therefore, any association does not necessarily imply causation. We believe that the authors have overlooked other more plausible explanations for an association between STA and surgical complications.

    The paper does not explain why some patients had STA and others TA. Many surgeons use TA for uncomplicated phacoemulsification, and STA or other blocks when surgical difficulties are anticipated: e.g. small pupil, dense cataract. For very dense cataracts, large-incision (manual) cataract surgery may be preferred: this has a different complication profile, and generally requires STA or other blocks. We suspect that surgeons chose STA for "higher-risk" cataracts, and this could easily explain the higher complication rate.

    There have been few randomised trials comparing surgical complication rates for TA and STA. The recent Cochrane review concluded 'there was not enough evidence to suggest that one technique would result in a higher or lower incidence of intraoperative complications' and predicted that a randomised trial comprising 116,884 eyes would be required.(2)

    We agree that, for many cases, topical (or topical-intracameral) anaesthesia may be the nearest to an 'ideal' anaesthesia, but for many other cases, STA may be nearest to the ideal. Joint Colleges Guideline 2012 stated: "When deciding which type of anaesthesia to use, consideration needs to be given to patient, surgical and operator factors....No local anaesthetic technique is entirely safe."(3) Clinicians should continue to use informed judgement in recommending appropriate anaesthesia for their patients.

    Tom Eke, Consultant Ophthalmologist, Norwich and Norfolk University Hospital, Norwich, UK

    Chandra M Kumar, Professor and Senior Consultant in Anaesthesia, Khoo Teck Puat Hospital, Singapore

    References

    1. Thevi T, Godinho MA. Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients. Br J Ophthalmol 2016;100:1708-1713.

    2. Guay J, Sales K. Sub-Tenon's anaesthesia versus topical anaesthesia for cataract surgery. Cochrane Database of Systematic Reviews 2015, Issue 8. Art. No.: CD006291. DOI: 10.1002/14651858.CD006291.pub3.

    3. Kumar CM, Eke T, Dodds C, et al. Local Anaesthesia for Ophthalmic Surgery. Royal College of Anaesthetists, Royal College of Ophthalmologists, London; 2012.

    Conflict of Interest:

    None declared

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  3. Comments on: Five-year results of Small Incision Lenticule Extraction (ReLEx SMILE)

    We read with great interest article entitled "Five-year results of Small Incision Lenticule Extraction (ReLEx SMILE)" by Blum et al (1). They concluded SMILE to be an effective, stable and safe procedure for treatment of myopia and myopic astigmatism in the long term. However, few queries come to our mind.

    In their study they observed regression of 0.48 D over a period of five years, which they attributed mainly to a subset of seven eyes. Although, in one eye cap perforation was noted, other six eye's regression was assumed to be result of long-term growth of the axial length, as most of these patients were 24 - 25 years of age at time of surgery. As a beginner, it would be helpful to us if a nomogram can be devised according to age as most of our patient undergoing SMILE are in the age group of 22 to 30 years to obviate unexpected outcomes. Present study being the longest follow up study till date, offers to be a perfect setting for such an analytical observation, providing further refinement of our refractive procedure. We encourage the authors to do the same.

    Authors also mentioned corneal topography and higher order aberrations(HOA) using Wave front measurements in methods section, but no results regarding the same were described. As most of the studies suggest that the posterior corneal surface remains stable till one year follow up (2,3), it would have been interesting to note the long term changes in posterior elevation. Similarly, most of the studies have reported SMILE to induce HOA's, though less than LASIK but no long term results are there (4,5). Such analysis would again strengthen the safety of profile offered by SMILE.

    We congratulate the authors on a thorough research and hope our discussion adds to their work.

    References:

    1. Blum M, Taubig K, Gruhn C, Sekundo W, Kunert KS. Five-year results of small incision lenticule extraction (ReLEx SMILE). Br J Ophthalmol. 2016 Sep;100(9):1192-5.

    2. Zhao Y, Li M, Zhao J, Knorz MC, Sun L, Tian M, Zhou X. Posterior corneal elevation after small incision lenticule extraction for moderate and high myopia.PLoS One. 2016 Feb10;11(2):e0148370.

    3. MM Wang B, Zhang Z, Naidu RK, Chu R, Dai J, Qu X, Yu Z, Zhou H. Comparison of the change in posterior corneal elevation and corneal biomechanical parameters after small incision lenticule extraction and femtosecond laser-assisted LASIK for myopia correction. Cont Lens Anterior Eye. 2016 Jun;39(3):191-6.

    4. Sekundo W, Gertnere J, Bertelmann T, Solomatin I. One-year refractive results, contrast sensitivity, high-order aberrations and complications after myopic small-incision lenticule extraction (ReLEx SMILE). Graefes Arch Clin Exp Ophthalmol. 2014 May;252(5):837-43.

    5. Wu W, Wang Y. Corneal higher-order aberrations of the anterior surface,posterior surface, and total cornea after SMILE, FS-LASIK, and FLEx surgeries. Eye Contact Lens. 2016 Nov;42(6):358-365.

    Conflict of Interest:

    None declared

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  4. Re: Response to AREDS supplements according to genetic factors: survival analysis approach using the eye as the unit of analysis

    We read with interest the article by Seddon, Silver, and Rosner [1], in which the authors studied progression from intermediate AMD to either geographic atrophy or choroidal neovascularization as a function of genetic risk and AREDS treatment assignment. This study of 4124 eyes by leaders in AMD genetic epidemiology is by far the largest series to analyze and validate a gene/treatment interaction. The authors show that CFH and ARMS2 interact statistically with AREDS treatment in opposing directions. The demonstrated allele dosage response to the AREDS formulation makes it logical that patients with the greatest CFH risk and the lowest ARMS2 risk would derive the least benefit from the AREDS formulation. Guided by these individual gene/treatment interactions, the authors investigated the interaction of composite genotype groups with the AREDS formulation. They defined "high" risk CFH as having 1 or 2 CFH risk alleles and "low" risk ARMS2 as having 0 ARMS2 risk alleles. Eyes of patients with 1 or 2 CFH risk alleles and with no ARMS2 risk alleles (33% of the study set) derive no benefit and had a trend toward increased CNV (HR 1.54) with a highly significant interaction coefficient (p=0.024). Knowing that one-third of individuals derive no benefit from the AREDS formulation is important. Millions of patients could avoid the cost and the occasional side effects associated with regular consumption of the AREDS formulation. The authors' decision to include patients with 1 CFH risk allele in the "high" CFH risk genotype group dilutes the impact of 2 CFH risk alleles. Given the identified dosage effect of CFH risk allele number, there is no scientific basis to fit the data to a Mendelian model of dominant genetics. Doing so potentially obscures the effects of the AREDS formulation in individuals at greatest risk of progression to CNV. We ask the authors to evaluate CNV risk in individuals with 2 CFH and 0 ARMS2 risk alleles treated with the AREDS formulation compared to placebo. This relatively straightforward analysis may reveal outcomes relevant for the optimal management of patients with AMD. Carl C. Awh, Brent Zanke 1. Seddon JM, Silver RE, Rosner B. Response to AREDS supplements according to genetic factors: survival analysis approach using the eye as the unit of analysis Br J Ophthalmol 2016;100:1731-1737 doi:10. 1136/bjophthalmol-2016-308624 Conflict of Interest Consultant, equity investor, ArcticDX (CCA) Employee, equity holder, Arctic DX (BW)

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

    Response to e-letter to the editor

    We thank Dr. Mourits and co-workers for their interest and comments regarding our manuscript on impression-free three-dimensional (3D) printed anophthalmic socket, and appreciate their recognition of its value in the manufacturing of an ocular prosthesis.(1)

    Dr. Mourits and co-workers propose an alternative technique, impression mould through silicon injection in the anophthalmic socket, which is subsequently scanned with magnetic resonance imaging (MRI), and further 3D processed. This technique, however, renews the manual step of impression moulding, which reintroduces a non-digital procedure in the digital domain.

    We confirm the benefit of MRI over cone-beam computed tomography (CBCT) as radiation-free option.(2) However, we would like to highlight our concerns on the current use of MRI for the purpose of imaging the anophthalmic socket. First, spatial resolution of MRI is lower than CBCT, since MRI is characterized by geometric distortion produced by magnetic susceptibility, particularly at the air-tissue interface.(3,4) Second, longer acquisition times in MRI potentially result in more variable delineation.(5) Manual delineation in MRI, in contrast to computer- assisted delineation in CT, requires expertise and is time-consuming. Third, adequate MRI protocols and preferred coils for orbital scanning with high resolution and signal-to-noise ratio within reasonable measurement times are as yet not established.(6) By contrast, in CT, the process of delineation of soft tissue for calculation of orbital soft tissue volume is validated, reliable and accurate.(7) Finally, MRI in children requires general anaesthesia, which is associated with increased morbidity.(8)

    Continuous improvement in MRI imaging will help to further develop this innovative concept. We encourage Dr. Mourits et al to publish the data they shared on the use of a mould and special MRI orbital scanning.

    Bibliography

    1. Ruiters S, Sun Y, de Jong S, et al. Computer-aided design and three-dimensional printing in the manufacturing of an ocular prosthesis. Br J Ophthalmol 2016 ;100:879- 881.

    2. Brenner DJ, Hall EJ. Computed tomography--an increasing source of radiation exposure. N Engl J Med 2007;357(22):2277-84.

    3. Ludwig U, Eisenbeiss AK, Scheifele C, et al. Dental MRI using wireless intraoral coils. Sci Rep 2016;6:23301.

    4. Sumanaweera TS, Glover GH, Binford TO, et al. MR susceptibility misregistration correction. IEEE Trans Med Imaging 1993;12(2):251-9.

    5. Karlo C, Reiner CS, Stolzmann P, et al. CT- and MRI-based volumetry of resected liver specimen: comparison to intraoperative volume and weight measurements and calculation of conversion factors. Eur J Radiol 2010;75(1):e107-11.

    6. Georgouli T, James T, Tanner S, et al. High-resolution microscopy coil MR-Eye. Eye (Lond) 2008;22(8):994-6.

    7. Regensburg NI, Kok PH, Zonneveld FW, et al. A new and validated CT -based method for the calculation of orbital soft tissue volumes. Invest Ophthalmol Vis Sci 2008;49(5):1758-62.

    8. Cot? CJ, Wilson S. Guidelines for Monitoring and Management of Pediatric Patients Before, During, and After Sedation for Diagnostic and Therapeutic Procedures: Update 2016. Pediatr Dent 2016;38(4):13-39.

    Conflict of Interest:

    None declared

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  6. Intra ocular pressure control and fluctuation

    The effect of treatment with selective laser Trabeculoplasty

    Conflict of Interest:

    None declared

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  7. Impact of initial visual acuity on anti-VEGF treatment outcomes in patients with macular oedema secondary to retinal vein occlusions in routine clinical practice

    Impact of initial visual acuity on anti-VEGF treatment outcomes in patients with macular oedema secondary to retinal vein occlusions in routine clinical practice Dan Calugaru, Mihai Calugaru Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania Re: Impact of initial visual acuity on anti-VEGF treatment outcomes in patients with macular oedema secondary to retinal vein occlusions in routine clinical practice. Wai et al. Br J Ophthalmol 2016;http:/dx.doi.org/10.1136/bjophthalmol-2016-308727.

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

    1. The study was retrospectively conducted with the existence of a selection bias because the choise of the specific anti-vascular endothelial growth factor (VEGF) agent was based on physician and patient preference. In addition, patients were retreated based on investigator determination of the presence of subretinal or intraretinal fluid as seen either by comprehensive ophthalmic examination and/or spectral-domain optical coherence tomography.

    2. The authors stated that there were relatively few numbers of ischaemic patients in their series although fluorescein angiography was performed in only 60.45% of the patients and no criteria used for the classification of patients as having ischaemic retinal vein occlusion (RVO) were indicated.

    3. The authors concluded that RVO patients with better initial visual acuities (VA) showed a nonsignificant change in VA and central subfield thickness (CST) over 12 months of treatment; conversely, patients with poor initial VAs showed dramatic improvements in Early Treatment Diabetic Retinopathy Study (ETDRS) letters and CST.

    4. In 2015, we documented for the first time (2), the impact of initial VA on bevacizumab (Avastin; Genentech, Inc., San Francisco, CA) treatment outcomes in patients with macular oedema secondary to acute central/hemicentral retinal vein occlusions. Although VA improvements at month 36 were significant in patients with both nonischaemic and ischaemic occlusions, the magnitudes of response to treatment were totally different, namely, an increase in VA of 17.5 letters (from 48.6 to 65.75 letters) in case of nonischaemic forms and of 26.81 letters (from 7.6 to 34.41 letters) in patients with ischaemic occlusions. The proportions of VA increases (from baseline values) were 36% in patients with better initial VA and 352.7% in patients having a poor initial VA, respectively. Such a comparison helped us to know that the intravitreal bevacizumab therapy was more effective in patients with ischaemic occlusions who required a significantly higher number of injections. In contrast with VA changes, the magnitudes of CST response to treatment were different, for example, a decrease of 300.49 microns in cases of nonischaemic and 351.33 microns in patients of ischaemic occlusions. However, the proportions of CST reductions (from baseline values) were similar in the nonischaemic and ischaemic groups (56.62% and 56.54%, respectively). So, the anatomic outcomes did not mirror the visual results mentioned above.

    Altogether, the assumption according to which patients with poor initial VA may benefit most from anti-VEGF suppression and vice versa, seems to be a somewhat paradoxical and counter-intuitive finding because patients with poor initial VA usually have advanced lesions which are difficult to be recovered. And yet, this assertion is logical since patients with low initial VA have a larger range of the interval in which VA can be improved in comparison with patients having a better initial VA with a more narrow interval and with small possibilities for improving. References 1. Wai KM, Khan M, Srivastava S, et al. Impact of initial visual acuity on anti-VEGF treatment outcomes in patients with macular oedema secondary to retinal vein occlusions in routine clinical practice. Br J Ophthalmol 2016; http:/dx.doi.org/10.1136/bjophthalmol-2016-308727. 2. Calugaru D, Calugaru M. Intravitreal bevacizumab in acute central/hemicentral retinalvein occlusions: three-year results of a prospective clinical study. J Ocul Pharmacol Ther 2015;31(2):78-86.

    Conflict of interest: None declared

    Conflict of Interest:

    None declared

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  8. Outcome of two-muscle surgery for large-angle intermittent exotropia in children - A comment

    We read the article titled "Outcome of two-muscle surgery for large- angle intermittent exotropia in children" by the authors Ki Won Jin and Dong Gyu Choi with great enthusiasm.1 The authors have compared the success of two muscle surgery for large angle (>=40 Prism Diopters (PD)) vs moderate-angle (>=20 and <30PD) intermittent exotropia. Neither of the two ranges described, include deviation between 30 to 39PD. Whether these deviations were excluded or this is a typographical error is subject to speculation. The range of exotropia in the large angle group was upto 70PD. Several prior studies have shown that success rates of two muscle surgery drop down significantly as the exotropia increases beyond 50PD2 and therefore three or four muscle surgery is recommended.3 Including such larger deviations skews the data and the chances of failure automatically increases in Group A of the study. We believe that a better comparison would have been between the moderate angle group and a second group of 35 - 50PD. None of the patients in the above study had symptomatic diplopia in lateral gaze or palpebral fissure changes at any postoperative visit in spite of performing large 9.5mm lateral rectus recession and 7mm medial rectus recession in at least some of the patients. This observation is unlike prior observations4 and our experience too with large recess-resect surgery. Lastly the authors have not compared the two groups in terms of refractive error which is an important factor leading to variations in preoperative measurement of deviation and the effect of surgery.5 Nonetheless we would like to congratulate the authors for conducting this important study that probably suggests that large angle intermittent exotropia warrants more than two horizontal rectus muscle surgery in order to achieve motor success in majority of patients.

    Conflict of Interest:

    None declared

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  9. 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:

    None declared

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  10. 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

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