697 e-Letters


    We have read with interest the article by Han et al.,1 in which the authors compare the outcomes of myopia correction using small incision lenticule extraction (SMILE) versus laser in situ keratomileusis (LASIK) using the VisuMax® femtosecond laser (FS) to cut the corneal flap, and we have some concerns regarding this study we would like to share with the authors.
    It is noteworthy that the authors found that only 65% of eyes were within ± 0.50 diopters of the attempted spherical equivalent correction after FS-LASIK, these results are clearly worse that those generally obtained with LASIK. It is accepted that the results obtained with excimer laser ablation, either using a surface ablation approach, or LASIK performed with mechanical microkeratome (MK) or using the Intralase® FS platform to correct myopia are quite similar.2,3 Indeed, our group has that 95% of unselected eyes with myopia of -3.9±1.5D3 and 80% of eyes with high myopia (-8.7±1.2D)4 were within ± 0.5D of emmetropia after LASIK. For this reason, we believe that the main conclusion of the article by Han et al.1 that “long-term outcomes of both SMILE and FS-LASIK are safe and equally effective for myopic and astigmatic correction” is clearly biased. In other words, the results of SMILE should have not been compared with a FS laser platform that does not seem to achieve the benchmark results clearly established for LASIK when correcting myopia.
    It should be highlighted that different FS platforms appr...

    Show More
  • Potential hazards of silicone oil released by the syringes

    Dear editor, we received with interest the comments by Wambier et al.1 They provided interestingly new insights in possible adverse effects of silicone oil on the human body. If enlarged lymph nodes and skin nodules assumed as sarcoidosis, and lumps in the abdomen of diabetic patients diagnosed as insulin fat hypertrophy are proved to be secondary to the silicone oil released by the syringes, a remarkable paradigm shift will be achieved. Incidentally, the idea of an inflammatory/immunological association to the presence of silicone oil droplets is in agreement with our yet unproven hypothesis that agitation of the syringe, silicone oil and a susceptible drug may cause non-infectious endophthalmitis after intravitreal injections.2
    However, we have to disagree with two other comments by the authors. Firstly, we employed two complementary techniques of assessing the presence of silicone oil from the syringes: light microscopy and Fourier-transform infrared spectroscopy.3-5 While the former allowed us to state that agitation of the syringe leads to a much higher release of silicone oil droplets with consistent and reproducible data, the latter showed that all models analysed have silicone oil in their interior, except for the oil-free one. Additionally, although it seems more reasonable, the use of a staining method might yield false-positivity, as we saw in our preliminary study.4
    Secondly, we believe that flushing the syringes with saline before drawing the drug...

    Show More
  • Reliability of Bruch’s membrane opening minimum rim width (BMO-MRW) and retinal nerve fibre layer thickness (RNFLT) with optical coherence tomography (OCT)

    Dear Editor,
    With great interest, we have read the article by Feihui et al.[1]
    This study has investigated the sensitivities and specificities of different diagnostic criteria based on the OCT for glaucoma detection. According to the article abnormal superotemporal and inferotemporal RNFLT attained a higher sensitivity than abnormal superotemporal and inferotemporal BMO-MRW to detect mild glaucoma. However, our query arises when “Integration of RNFLT / BMO-MRW assessment was done”. The author stated, integrating RNFLT and BMO-MRW assessment did not change the sensitivity and specificity of RNFLT but increased the sensitivity of BMO-MRW for detection of glaucoma. To quote the author, the author paradoxically stated “ Our finding underscores the importance of RNFL imaging and measurement in the diagnostic evaluation of glaucoma”. We are interested to know if sensitivity and specificity on combination is increased, why would the diagonostic performance not increased? Reis et al stated, Bruch's membrane opening minimum rim width (BMO‐MRW) reproducibility were comparable and excellent in both healthy subjects and patients with glaucoma to that of RNFLT measurements.[2]
    The article also did not include head tilt in the confounding covariates, as it was previously stated, head tilt significantly affects OCT image orientation as measured by the FoBMO angle.[3]
    The article has also not mentioned dimensions of the optic nerve head (ONH) as stated previo...

    Show More
  • Here is your injection: would you like with or without silicone oil?

    Dear editor, we have read with great interest the article presented by Melo et al.1 The authors provide good evidence of silicone oil release in injections from lubricated syringes. However, the likelihood of false-negative data may have been high because of lack of a staining method (Sudan III, for example) to differentiate and highlight small droplets, as previously described.2

    Although injectable fluid contamination with syringe silicone oil has been known for decades,3,4 the lack of awareness of all medical specialties about this problem is impressive. The most concerning, still controversial long-term effect of silicone oil exposure is the development of an autoimmune/inflammatory syndrome induced by adjuvants, also known as ASIA syndrome.5

    Given the massive amount of injections given worldwide, silicone oil injected seems safer than one would imagine, however, it is worth remembering that if the physician is unaware of the fact of the silicone oil injection, the diagnosis is omitted as a possible hypothesis. Enlarged lymph nodes or skin nodules with evidence of granulomas are assumed as sarcoidosis, and lumps in the abdomen of diabetic patients are all diagnosed as insulin fat hypertrophy, and if a biopsy is performed, the likely cause of the granuloma would be the injected therapeutic protein or an autoimmune phenomenon. If the physicians are informed that a patient received silicone oil injections the diagnoses change to silicone oil induced granuloma...

    Show More
  • Letter to Editor

    We have read the paper written by Avila MY et al “Randomised prospective clinical trial of platelet-rich plasma injection in the management of severe dry eye” . Authors have evaluated the effectiveness of platelet-rich injection in lacrimal gland plus free-demand topical lubricants drops in Sjögren’s syndrome severe dry eye patients . Diagnosis was based on Schirmer I, break-up time(BUT), ocular surface staining (Oxford grid) and OSDI . Achieved results in interventional group showed a Schirmer I (6,7+/-0,9 vs 9,2+/-1 mm, p<0,002), BUT (6,4+/-0,4 vs 4,4+/-0,3 secs p=0,0005), staining (2,15+/-0,15 vs 1,2+/-0,18 p<0,001) and OSDI (59+/-0,4 VS 34+/-4, p<0,001). Surprisingly authors have not included the lacrimal osmolarity test, the most valuable diagnostic tool to rule in/out this disease (S and Sp >90%) . Unfortunately Schirmer I (without anesthesia) evaluates not just basal lacrimal tearing, it also measures reflex response giving confounding bias in measured result. Surface staining (a qualitative variable) was mistakenly analyzed with a t-paired student test. Regarding OSDI, PRP patients showed a test improvement (pre 59+/- 4,0 vs post 34+/-4,0) without change in disease severity. Finally, this trial enrolled a low number of patients (n=15) that according to authors assumptions we would expect a much greater sample size (Epidat 4.1 n=417 eyes). In conclusion, a novel and interesting new treatment for Sjögren’s dry eye patients that must be confirmed in the f...

    Show More
  • Re: Choroidal Thickness in Macular Telangiectasia Type 2

    Dear Editor,

    We appreciate the interest in our paper by Kumawat and Kumar, and the opportunity to address their comments. With regards to axial length, it is certainly known to be correlated with choroidal thickness. However, this information was not routinely obtained in our retina clinic and was not available for most patients in the study. We were able to account for spherical equivalent in our multivariate model, which may serve as a proxy for axial length. We agree that accounting for at least one of these variables is required for studies on choroidal thickness. We appreciate the Kumawat and Kumar’s suggestion to categorize patients based on stage of disease (proliferative vs nonproliferative). We had considered this approach, however the small number of patients with proliferative disease (only 4) made this less ideal from a statistical standpoint. Subretinal neovascularization was included in our univariate analysis but was not found to be statistically significant with regard to choroidal thickness, so it was not further considered in our multivariate assessments. Lastly, while inter-ocular asymmetry in choroidal thickness may exist, eye laterality was not found to be a significant variable affecting choroidal thickness in our univariate analysis (p = 0.87) and thus was also not included in multivariate models. We once again thank Dr. Kumawat and Dr. Kumar for their interest in our work.

  • Comment on 'Clinical presentation and management of corneal fistula'

    Dear Editor,
    We have read with great interest the article by Singhal et al 1 on 'Clinical presentation and management of corneal fistula'. The authors have rightly highlighted the point that failure to perform simple test like Seidel test in cases of corneal ulcer, can lead to missing the diagnosis of corneal fistula, which in turn can lead to serious complications like endophthalmitis, panophthalmitis and phthisis bulbi.
    One of the complications of persistent corneal fistula is the formation of anterior capsular cataract. It would have been more insightful if the authors had mentioned as to how many patients had developed anterior capsular cataract during follow up, as this can lead to a change in the future management of the eye.
    Also, the authors have not mentioned the type of anaesthesia for doing the procedure. As creating the grooves around perforation to tuck in the tenons graft is difficult due to the friability of corneal tissue, the type of anaesthesia has a bearing on the intra operative surgical procedure. As doing the technique in topical anaesthesia will be technically challenging and administration of peribulbar block could lead to extrusion of the intraocular contents or extension of the perforation.
    Although the study mentions the surgical technique for closing the fistula with a tenons patch graft, it does not mention the regimen of postoperative medical management.
    In the discussion, the authors have mentioned that...

    Show More
  • Reply to the letter of Dr. Tarannum Mansoori

    We would like to thank Dr. Tarannum Mansoori for the interest in our study, “Intraocular pressure change after injection of intravitreal dexamethasone (Ozurdex) implant in Korean patients” and highlighting important issues about the intraocular pressure (IOP) measurement methods and the correlation of IOP with age.1
    We used KT-800 Non-Contact Tonometer (Kowa, Tokyo, Japan) to measure IOP initially and rechecked with GAT if necessary. Unless the patient was diagnosed with glaucoma, NCT was initially used to measure both pre- and post-injection IOP.
    As Dr. Tarannum Mansoori has pointed out, we also agree that GAT is the gold standard for IOP measurement. If the IOP measured with NCT was found to be high, it was always rechecked with GAT. GAT was used in 2 situations in our study. First, when the patients had a previous history of glaucoma, and second, when the patients’ IOP as measured with NCT was high (greater than 20). Thus, in cases of high IOP, the measurement involved NCT and was also always double checked with GAT. Moreover, multiple IOP measurements were obtained with GAT in cases of high IOP, and the average value of the measurements was regarded as the final IOP.
    The range of age of the patients for injection of intravitreal dexamethasone was broad, from 16 to 88 years. We know that very young age (less than six years) or an older age are risk factors for steroid-induced glaucoma.2 However, regrettably, we have not performed any further analysis...

    Show More
  • Response to letter

    We thank the authors for their careful perusal of our study report and thoughtful observations. We agree that as demonstrated by the large population study1,2 referenced by us and by them, the rate of complications with cataract surgery is non-homogenous and increases dramatically with advanced stage cataracts – as much as 200%+ increase in rate of PCT in cases with high grade cataract, pseudoexfoliation and other comorbidities. In fact, with the co-existence of multiple factors, the compound rate can be even higher.

    Our pilot study was in patients with advanced cataracts and multiple co-existing ocular pathologies and given the small sample size we are not surprised that the study point estimate for the PCT rate may be on the higher end of the overall range demonstrated by the larger population study. In addition, the randomized control design of the clinical trial further validates a PCT rate which was similar for both treatment and control groups. Certainly, an informed reader would appreciate that such a small trial is underpowered to be conclusive regarding the small difference between the two groups so no claims should be made about the slightly better rate of PCT and lower trend demonstrated in the miLOOP group.

    What is important to appreciate from both the population study and our pilot data is that the rate of PCT is not the same for all cataract surgeries and there is a multiplier effect in certain subgroups and subpopulations. Our authorship team...

    Show More
  • Concerns regarding complication rates of recent prospective investigation

    We are interested in the work of Ianchulev et al in their recent interventional randomized controlled trial.[1] What piqued our interest was the rate of posterior capsular tears (PCT). 4/53 (7.5%) patients in the miLOOP+phaco group experienced PCT, and 5/48 (10.4%) phaco-alone controls with PCT. These rates are much higher than standard phacoemulsification reports. The authors refer to a large study that identified advanced cataracts increased risk of PCT at comparable levels.[2] That same group published investigations expounding upon this.[3-4] Advanced cataracts were specifically identified as brunescent/white cataracts, contrasting Grade 3-4 in the miLOOP study (curiously described as LOCSIII classification in the manuscript).

    Using the risk calculation,[3] the range of composite adjusted odds ratio (aOR) for the miLOOP study was 49.93 (25-28% risk) to an aOR of 0.87 (<1% surgical risk). The average patient from the miLOOP investigation had an aOR of 4.43, thus <5% PCT risk.

    Our concerns: First, the authors state that “There was a trend towards a lower rate of capsular tear during the phaco portion with miLOOP-assisted phaco (7.5%) compared to standard phaco (10.4%).” Given the numbers representing these percentages this is an inappropriate description of this relationship.

    Let us assume that a control group presented with a PCT rate similar to that reported in literature: <5%. Here, miLOOP-phaco PCT rate would be higher than the control...

    Show More