Factors influencing the reliability of measurements in eyes with full-thickness macular holes: are we measuring incorrectly?

PURPOSE: The calliper function is used for manual measurements of full thickness macular holes (FTMHs). We aimed to investigate whether a reproducible difference could be detected beyond interobserver variability between two commonly used manufacturers in their manual calliper facility in spectral domain optical coherence tomography (OCT) for metrics related to FTMH. METHODS: This is a non-interventional, retrospective, observational study. Two independent observers examined 8 eyes (16 OCT) scans and 128 measurements (minimal linear diameter (MLD), basal diameter and hole height on both sides) of FTMHs, taken on Heidelberg Spectralis and Topcon Triton (OCT machines). The interobserver agreement and OCT machine agreement of measurements were analysed by Bland-Altman plots and intraclass correlation coefficient (ICC) analysis. Spectralis and Triton had 125 µm and 50 µm horizontal b-scan spacing, respectively. RESULTS: Overall, we report high absolute agreement in interobserver (ICC 0.991 (95% CI 0.985 to 0.995, p<0.001)) and OCT machine (ICC 0.993 (95% CI 0.987 to 0.996, p<0.001)) variability. Lower horizontal resolution in Triton compared with Spectralis leads to interobserver variability, in smaller horizontal measurements. Lower horizontal scanning density in Spectralis lead to relatively large interobserver variation if different reference scans were chosen, and consistently smaller MLD measurements than Triton. Vertical measurements without 1:1 scaling lead to inaccurate exaggerated oblique vertical measurements. Calliper function appears otherwise identically calibrated. CONCLUSIONS: We report excellent interobserver and OCT machine agreement in measurements. However, the paper shows several factors that could influence the reliability of measurements acquired in eyes with FTMHs, such as the dimension of the hole as well as different image resolution, density scanning protocols or vertical scaling of the OCT machines viewing platform.

Dislocated 4-haptic intraocular lens rescue with Gore-tex suture scleral re-fixation.

BACKGROUND: Dislocated IOL exchange conventionally involves manipulation within the anterior chamber which risks secondary injury to anterior chamber structures. We describe and evaluate a 4-haptic IOL rescue technique that avoids entering the anterior chamber and thus minimizes post operative inflammation, astigmatism and recovery time relative to conventional IOL explantation and replacement techniques. METHODS: Retrospective, non-randomized, interventional study of all patients undergoing 4-haptic IOL rescue performed by two independent vitreoretinal surgeons at a single UK centre over two years. SURGICAL TECHNIQUE: A limited peritomy is performed with four 25-gauge scleral ports placed to enable use of two forceps, an infusion and a chandelier. A further four 27-gauge sclerotomies are symmetrically placed on the nasal and temporal sclera at 3 mm from the limbus with a 5 mm vertical separation on either side. A pars plana vitrectomy is performed followed by chandelier illuminated, bimanual cleaning of the dislocated IOL using 27-gauge serrated forceps. Gore-tex sutures are threaded through the IOL islets within the vitreous cavity and externalized through the sclerotomies for scleral re-fixation followed by conjunctival closure. RESULTS: Seven patients underwent IOL recycling with Gore-Tex suture scleral re-fixation. All procedures were successful in repositioning the IOLs, with all patients satisfied with post-operative outcome. Mean (standard deviation) time to IOL dislocation was 13 (3) years. Median visual acuity significantly improved post-operatively from 0.85 logMAR (Interquartile Range [IQR]: 0.2-2.1) to 0.07 (0.02-0.60) logMAR (p = 0.02). No significant post-operative complications were noted apart from persistent cystoid macular oedema in one patient non-compliant with post-operative treatment. CONCLUSIONS: Transscleral refixation using Gore-Tex suture is an effective, safe and practical approach in the management of dislocated 4-piece IOLs.

Volumetric Biomarkers of Visual Outcome after Surgical Repair in Lamellar Macular Holes.

BACKGROUND: We investigate novel OCT parameters, based on the volumetric analysis of lamellar macular holes (LMHs), as prognostic indicators for visual outcomes after surgery. METHODS: LMHs were divided into degenerative LMHs (D-LMHs) and ERM-foveoschisis (ERM-FS). Pre-operative clinical, OCT linear and volumetric parameters were collected. Volumes were obtained using the OCT automatic segmentation, such as central retinal volume (CRV) and outer nuclear layer (ONL) volume, or using a novel method to calculate volumes of specific LMH entities like epiretinal proliferation (ERP), foveal cavity (FC) in D-LMH and schitic volume (SV) in ERM-FS. Univariate and multivariate linear regression analysis evaluated the factors predictive for post-operative best-corrected visual acuity (BCVA). RESULTS: We included 31 eyes of 31 patients (14 D-LMH,17 ERM-FS). A pre-operative BCVA ≤ 0.48 logMAR was a predictor for achieving ≤0.30 logMAR at final follow-up. A lower pre-operative BCVA (p = 0.008) and the presence of ERP (p = 0.002) were associated with worse visual outcomes post-surgery. Moreover, novel pre-operative OCT parameters significantly associated with worse post-operative BCVA, such as increased FC volume (p = 0.032) and lower CRV (p = 0.034) in the D-LMH subtype and lower CRV (p < 0.001) and ERP volume (p < 0.001), higher SV (p < 0.001) and foveal ONL volume (p < 0.001) in the ERM-FS subtype. CONCLUSIONS: Novel volumetric OCT parameters can be prognostic indicators of visual outcome following surgery in LMHs.

SF 6 COMPARED WITH C 2 F 6 FOR INFERIOR RHEGMATOGENOUS RETINAL REPAIR : The Manchester Pseudophakic Retinal Detachment Study.

PURPOSE: To compare SF 6 relative with C 2 F 6 in the anatomical and functional outcomes following pars plana vitrectomy for uncomplicated primary pseudophakic rhegmatogenous retinal detachment with inferior causative breaks. METHODS: This is a retrospective, comparative study on eyes with pseudophakic rhegmatogenous retinal detachment with inferior causative breaks that had small-gauge pars plana vitrectomy repair using SF 6 and C 2 F 6 tamponade between 2011 and 2020 at a tertiary centre in the United Kingdom. Primary outcome was single surgery anatomical success, and the secondary outcome was best-corrected visual acuity. Propensity score matching, using preoperative findings as covariates to account for relevant confounders, was performed. RESULTS: From 162 pseudophakic rhegmatogenous retinal detachment eyes with inferior causative breaks, the median (interquartile range) follow-up was 82 (52-182) days. The single surgery anatomical success was 156 (96.3%) overall: 47 of 47 (100.0%) and 109 of 115 (94.8%) in the SF 6 and C 2 F 6 groups, respectively ( P = 0.182). Relative to the SF 6 group, the C 2 F 6 group had a higher mean number of tears (SF 6 : 3.1[2.0], C 2 F 6 : 4.5[2.7], P = 0.002) and greater retinal detachment extent (SF 6 : 5.3[2.9], C 2 F 6 : 6.2[2.6] clock hours, P = 0.025). Following propensity score matching analysis, 80 eyes were matched with 40 in each group to homogenize preoperative factors. No significant difference was found in single surgery anatomical success and best-corrected visual acuity between the groups following propensity score matching. CONCLUSION: Primary pars plana vitrectomy with gas tamponade leads to a high single surgery anatomical success rate in uncomplicated pseudophakic rhegmatogenous retinal detachment with inferior causative breaks with no additional benefit associated with long-acting tamponade when comparing C 2 F 6 with SF 6 .

Global warming impact of fluorinated gases in ophthalmic surgeries at a tertiary eye center in India.

PURPOSE: Global warming is one of the greatest health threats of the 21 st century. The ophthalmic sector contributes to the emission of greenhouse gases, thus altering the natural environment. There is currently no data on global emissions of fluorinated gases in ophthalmic surgery. This retrospective study from 2017 to 2021 aims to report the carbon dioxide (CO 2 ) equivalence of sulfur hexafluoride (SF 6 ), hexafluoroethane (C 2 F 6 ), and octafluoropropane (C 3 F 8 ) at a tertiary eye center. METHODS: Data collected from 1842 surgical procedures that used injections of fluorinated gases were analyzed. Environmental impact (global warming potential over 100 years) was calculated by converting milliliters to grams by using modified ideal gas law at standard temperature and pressure for the canisters and then to their CO 2 equivalence. RESULTS: Though 70% of surgeries used C 3 F 8 , the least greenhouse effect causing fluorinated gas, the total carbon emission was 1.4 metric tons. The most common indication was macular hole surgery (36.86%). CONCLUSION: This study paves a step toward analyzing the problem statement, thus awakening us to contemplate options to make ophthalmic surgeries greener.

Cytokines in Immune-mediated "Non-infectious" Uveitis.

Uveitis is a significant cause of ocular morbidity and accounts for approximately 5 - 10% of visual impairments worldwide, particularly among the working-age population. Infections are the cause of ~ 50% cases of uveitis, but it has been suggested that infection might also be implicated in the pathogenesis of immune-mediated "non-infectious" uveitis. There is growing evidence that cytokines (i.e., interleukins, interferons, etc.) are key mediators of immune-mediated "non-infectious" uveitis. For example, activation of the interleukin-23/interleukin-17 signalling pathway is involved in immune-mediated "non-infectious" uveitis. Studies in animal models have been important in investigating the role of cytokines in uveitis. Recent studies of clinical samples from patients with uveitis have allowed the measurement of a considerable array of cytokines even from very small sample volumes (e.g., aqueous and vitreous humour). The identification of complex patterns of cytokines may contribute to a better understanding of their potential pathogenetic role in uveitis as well as to an improved diagnostic and therapeutic approach to treat these potentially blinding pathologies. This review provides further insights into the putative pathobiological role of cytokines in immune-mediated "non-infectious" uveitis.