Purpose: To compare the safety and efficacy profiles of Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK) in adult patients with Fuchs’ endothelial dystrophy. Methods: Electronic database search on MEDLINE and CENTRAL from inception to August 2017. We included all comparative studies of DMEK versus DSAEK in patients with diagnosed Fuchs’ endothelial dystrophy. Studies assessing rescue procedures were excluded to minimize bias. Primary outcome: mean difference in best-corrected visual acuity (BCVA) at 3, 6, and 12 months postoperatively. Secondary outcomes: rates of graft primary failure, rejection, and rebubbling; other graft-related issues; mean difference in endothelial cell density; subjective visual outcomes; and patient satisfaction. Results: A total of 10 retrospective studies of moderate methodological quality were included (n = 947 eyes, 646 DMEK). BCVA was better with DMEK at all evaluated time points (0.16 logMAR at 12 months) comparing to DSAEK (0.30 logMAR; p < 0.001). DMEK had a 60% lower rate of rejection (risk ratio (RR) 0.4, 95% CI (0.24, 0.67), p = 0.0005), but required more rebubblings (RR = 2.48, 95% CI (1.32, 4.64), p = 0.005). DMEK had more primary graft failures and less endothelial cell density loss, but statistical difference was not reached. More patients were satisfied after DMEK (odds ratio = 10.29, 95% CI (3.55, 29.80), p < 0.0001). Conclusion: DMEK showed better postoperative results regarding BCVA, patient satisfaction, and graft-related issues. However, the small number of studies with short follow-up times and other methodological issues prompt us to interpret these results carefully.

Purpose: To compare intracameral 20% sulfur hexafluoride (SF₆) versus 100% air as tamponade for graft attachment in Descemet membrane endothelial keratoplasty (DMEK). Methods: Using an electronic database search on MEDLINE and CENTRAL from inception to December 2017, we performed a literature review and meta-analysis including all comparative studies of SF₆ at a 20% concentration (20% SF₆) versus pure air (100% air) for anterior chamber tamponade in DMEK. The primary outcome was the rebubbling rate at the final observation. The secondary outcomes were 1) the graft detachment rate, 2) mean difference (MD) in best-corrected visual acuity (BCVA), 3) manifest refraction spherical equivalent, 4) central corneal thickness (CCT), 5) percentage of endothelial cell loss (ECL), and 6) rate of pupillary block by the final observation. Statistical analysis was performed using RevMan5.3 software. Results: Five retrospective studies were included, assessing 1195 eyes (SF₆ 277; air 918). The main indication for surgery was Fuchs endothelial dystrophy (SF₆ 85.2%; air 86.2%) and bullous keratopathy (SF₆ 10.8%; air 10.0%). Overall, studies were of moderate to good methodological quality. Patients in the SF₆ group required 58% less rebubbling procedures (risk ratio 0.42, 95% confidence interval (CI), 0.31–0.56, P < 0.0001). No differences were found regarding BCVA improvement (MD 0.03, 95% CI, −0.05 to 0.11, P = 0.49). SF₆ was associated with a minor hyperopic shift (MD 0.37 D, 95% CI, −0.95 to −0.21, P = 0.21). No differences were found regarding CCT, ECL, and rate of pupillary block (P > 0.05). Conclusions: In DMEK, 20% SF₆ tamponade and longer postoperative time supine were associated with 58% fewer rebubbling procedures, and an ECL not statistically different from using 100% air.

Purpose: Previous studies report that the response of retinal vessels to a decrease in oxygen (hypoxia) is vasodilation, thus increasing blood flow. We aimed to characterize the changes in retinal microvasculature induced by a mild hypoxia stress test in a healthy population, using ocular coherence tomography angiography (OCT‐A) technology.Methods: Interventional repeated‐measures study. The standardized hypoxia challenge test (HCT) was performed to all volunteers, according to the British Thoracic Society protocol. Ocular coherence tomography angiography (OCT‐A) was performed at three time‐points (baseline, during HCT and 30′ posthypoxia). Macular and peripapillary vessel densities were assessed using the built‐in software. To minimize bias, analysis was performed separately in right (OD) and left (OS) eyes. Repeated‐measures anova and mean comparison analysis were used as statistical tests (stata v13).Results: Studied population included 30 healthy subjects (14 women), with a mean age of 28.8 ± 4.2 [range 22–37] years. Baseline vessel density increased in hypoxic conditions and subsequently decreased to near‐baseline values in posthypoxia conditions. This pattern was observed for both eyes in both parafovea (OD: 55.3 ± 2.3 to 56.7 ± 1.9 to 55.8 ± 1.9, p < 0.05; OS: 56.9 ± 2.1 to 57.9 ± 1.9 to 57.3 ± 1.7, p < 0.05) and peripapillary (OD: 60.5 ± 0.5 to 62.6 ± 0.5 to 60.1 ± 0.4, p < 0.05; OS: 60.4 ± 0.4 to 62.3 ± 0.5 to 60.7 ± 0.4, p < 0.05) areas.Conclusion: To our knowledge, there are no published data specifically addressing mild hypoxia conditions and retinal microvasculature changes, using OCT‐A. This pilot study may pave way to better understand vascular responses in disease setting.

Purpose: We hypothesize that patients with type 1 diabetes (T1D) may have abnormal retinal vascular responses before diabetic retinopathy (DR) is clinically evident. Optical coherence tomography angiography (OCTA) was used to dynamically assess the retinal microvasculature of diabetic patients with no clinically visible retinopathy. Methods: Controlled nonrandomized interventional study. The studied population included 48 eyes of 24 T1D patients and 24 demographically similar healthy volunteers. A commercial OCTA device (AngioVue) was used, and two tests were applied: (1) the hypoxia challenge test (HCT) and (2) the handgrip test to induce a vasodilatory or vasoconstrictive response, respectively. The HCT is a standardized test that creates a mild hypoxic environment equivalent to a flight cabin. The handgrip test (i.e., isometric exercise) induces a sympathetic autonomic response. Changes in the parafoveal superficial and deep capillary plexuses in both tests were compared in each group. Systemic cardiovascular responses were also comparatively evaluated. Results: In the control cohort, the vessel density of the median parafoveal superficial and deep plexuses increased during hypoxia (F_1,23 = 15.69, P < 0.001 and F_1,23 = 16.26, P < 0.001, respectively). In the T1D group, this physiological response was not observed in either the superficial or the deep retinal plexuses. Isometric exercise elicited a significant decrease in vessel density in both superficial and deep plexuses in the control group (F_1,23 = 27.37, P < 0.0001 and F_1,23 = 27.90, P < 0.0001, respectively). In the T1D group, this response was noted only in the deep plexus (F_1,23 = 11.04, P < 0.01). Conclusions: Our work suggests there is an early impairment of the physiological retinal vascular response in patients with T1D without clinical diabetic retinopathy.

Purpose: The aim of this study is to assess the agreement between manual and automated gonioscopy for iridocorneal angle opening. Methods: The research is a cross-sectional observational study. Manual and automated gonioscopy were performed to consecutive patients in a glaucoma clinic. Iridocorneal angle opening grading was performed according to Shaffer’s classification. Automated gonioscopy was performed with NGS-1 automated gonioscope (NIDEK Co., Gamagori, Japan). The automated gonio-photos were graded by two independent observers. Agreement between automated and manual gonioscopy and also among raters was ascertained by Fleiss’ kappa statistic and comparison of area under curve. Results: In total, 88 eyes of 47 subjects were analysed. Mean age was 63 ± 10 years. Twenty eyes (22.7%) were excluded from grading due to poor quality images. Angle closure was detected in 23.4% with dynamic gonioscopy in comparison with 4.3% using automated image grading. The agreement for angle closure diagnosis between dynamic and automated gonioscopy was low (κ = 0.09 ± 0.10; p = 0.18). The area under curve for detecting eyes with angle closure showed poor accuracy between automated and manual methods (area under curve: 0.53 ± 0.05, 95% confidence interval: 0.44–0.62). There was modest inter-rater agreement for angle opening assessment of automated images with Fleiss’ kappa of 0.17 (95% confidence interval: 0.035–0.238). Conclusion: Manual and automated gonioscopy showed only slight agreement for the assessment of iridocorneal angle opening status. Further improvements of the NGS-1 automated gonioscopy and technique are desired for widespread use in a real-life setting.

Studies have suggested that corneal biomechanical properties influence intraocular pressure (IOP) measurements, namely central corneal thickness (CCT) and corneal hysteresis (CH). The present study aimed to investigate the associations of CH and CCT with glaucoma development. We performed a review of the literature and meta-analysis of observational studies (2006-2016) that included both adult glaucoma patients and controls and reported CCT and CH as outcomes. Nineteen studies were conside red eligible, and the mean difference (MD) between groups (patient and control) for both variables was used for statistical analyses. A total of 1,213 glaucoma and 1,055 healthy eyes were studied. Quan titative analysis suggested that CH was significantly lower in the glaucoma group than in the control group (MD=-1.54 mmHg, 95% CI [-1.68, -1.41], P<0.0001). Additionally, CCT was significantly lower in the glaucoma group than in the control group (MD=-8.49 µm, 95% CI [-11.36, -5.62], P<0.001). Corneal properties appear to differ between glaucoma patients and healthy controls. Our results emphasize the importance of corneal biomechanical properties in IOP interpretation and should support further studies on the influence of CH and CCT in glaucoma screening and diagnosis.