Retrieving A retained Heavy Silicone Oil Bubble: Two Novel Surgical Techniques.

PURPOSE: To describe two surgical techniques for rescuing a retained heavy silicone oil bubble in the posterior pole: 1) light pipe method and 2) perfluorocarbon liquid method. METHODS: The surgical techniques are described in detail, along with an illustrative video for each. RESULTS: A short 25-gauge metallic cannula and active suction pump are used for standard heavy silicone oil removal. Both surgical approaches are practical and effective options to complete the removal of heavy silicone oil when a bubble sinks to the posterior pole. CONCLUSION: Both the light pipe and perfluorocarbon methods are suitable to remove retained heavy silicone oil and thus avoid the need for further incisions and the risks associated with the use of larger gauge instrumentation.

PREDICTION OF MACULAR HOLE SIZE PROGRESSION BASED ON BASELINE OPTICAL COHERENCE TOMOGRAPHY FINDINGS.

PURPOSE: To quantify the rate of idiopathic macular hole progression from presentation and identify factors that may influence stratification and urgency for surgical listing based on the initial optical coherence tomography scans. METHODS: The minimal linear diameter (MLD), base diameter (BD), and hole height on nasal and temporal sides of idiopathic macular hole were measured on spectral domain optical coherence tomographies, on initial presentation and just before surgery. Mean hole height, hole height asymmetry (absolute difference between nasal and temporal height), MLD/BD, and MLD change per day (MLD/day) were calculated for each patient. Multivariable linear regression analysis with MLD/day as the dependent variable was performed to identify significant risk factors for MLD progression. Minimal linear diameter was grouped to quintiles: 1: ≤290 µ m, 2: >290 µ m and ≤385 µ m, 3: >385 µ m and ≤490 µ m, 4: >490 µ m and ≤623 µ m, and 5: >623 µ m. RESULTS: In 161 eyes (157 patients), we report significant associations with MLD/day: 1) MLD/BD ( P = 0.039) (i.e., wide BD relative to MLD lead to faster progression of MLD), 2) hole height asymmetry ( P = 0.006) (larger absolute difference between nasal and temporal hole height lead to faster progression), and 3) days between scans ( P < 0.001) (longer duration between scans had reduced MLD/day, indicating more rapid increase initially then plateaux), and relative to MLD Quintile 1, MLD Quintile 3 ( P = 0.002) and MLD Quintile 4 ( P = 0,008), and MLD Quintile 5 ( P < 0.001) all lead to a reduced MLD/day rate on multivariable regression. CONCLUSION: In addition to finding that the previously reported initial smaller MLD is a risk factor for rapid MLD progression, we report two novel findings, large hole height asymmetry and a low MLD/BD (wide base relative to MLD), that represent significant risk factors. These factors should be taken into consideration on presentation to stratify timing of surgery.

Broadening risk factor or disease definition as a driver for overdiagnosis: A narrative review.

Medical overuse-defined as the provision of health services for which potential harms exceed potential benefits-constitutes a paradigm of low-value care and is seen as a threat to the quality of care. Value in healthcare implies a precise definition of disease. However, defining a disease may not be straightforward since clinical data do not show discrete boundaries, calling for some clinical judgment. And, if in time a redefinition of disease is needed, it is important to recognize that it can induce overdiagnosis, the identification of medical conditions that would, otherwise, never cause any significant symptoms or lead to clinical harm. A classic example is the impact of recommendations from professional societies in the late 1990s, lowering the threshold for abnormal total cholesterol from 240 mg/dl to 200 mg/dl. Due to these changes in risk factor definition, literally overnight there were 42 million new cases eligible for treatment in the United States. The same happened with hypertension-using either the 2019 NICE guidelines or the 2018 ESC/ECC guidelines criteria for arterial hypertension, the proportion of people overdiagnosed with hypertension was calculated to be between 14% and 33%. In this review, we will start by discussing resource overuse. We then present the basis for disease definition and its conceptual problems. Finally, we will discuss the impact of changing risk factor/disease definitions in the prevalence of disease and its consequences in overdiagnosis and overtreatment (a problem particularly relevant when definitions are widened to include earlier or milder disease).

INVERTED INTERNAL LIMITING MEMBRANE FLAP TECHNIQUES AND OUTER RETINAL LAYER STRUCTURES.

PURPOSE: To examine the influence of the inverted flap (IF) internal limiting membrane (ILM) technique in macular hole (MH) closure on outer retinal layers after MH surgery. METHODS: Retrospective study. Postoperative position of ILM, recovery rate of external limiting membrane and ellipsoid zone, and best-corrected visual acuity were evaluated. The Inserted group, where the IF is placed inside the hole, was compared with the Cover group, where the IF completely covers the hole. RESULTS: Sixty-two eyes of 58 patients who underwent vitrectomy and ILM peeling with the IF technique for large MHs (>400 µm) with successful MH closure and a follow-up of 12 months were evaluated. In the 24 eyes of the Inserted group, there was no regeneration of external limiting membrane or ellipsoid zone after 12 months. In the 38 eyes of Cover group, external limiting membrane recovered in 55.3% of patients 1 month after surgery, and in 86.1% after 12 months. The elipsoid zone layer was present in 58% of the patients. CONCLUSION: Poorer anatomical and visual results were associated with the IF technique where ILM insertion occurs compared with ILM placed over the hole. These findings suggest that insertion of the ILM in the hole might prevent outer retinal layers realignment and visual recovery in MH surgery.

Tomographic Structural Changes of Retinal Layers after Internal Limiting Membrane Peeling for Macular Hole Surgery.

PURPOSE: To highlight tomographic structural changes of retinal layers after internal limiting membrane (ILM) peeling in macular hole surgery. METHODS: Nonrandomized prospective, interventional study in 38 eyes (34 patients) subjected to pars plana vitrectomy and ILM peeling for idiopathic macular hole. Retinal layers were assessed in nasal and temporal regions before and 6 months after surgery using spectral domain optical coherence tomography. RESULTS: Total retinal thickness increased in the nasal region and decreased in the temporal region. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) showed thinning on both nasal and temporal sides of the fovea. The thickness of the outer plexiform layer (OPL) increased. The outer nuclear layer (ONL) and outer retinal layers (ORL) increased in thickness after surgery in both nasal and temporal regions. CONCLUSION: ILM peeling is associated with important alterations in the inner retinal layer architecture, with thinning of the RNFL-GCL-IPL complex and thickening of OPL, ONL, and ORL. These structural alterations can help explain functional outcome and could give indications regarding the extent of ILM peeling, even though peeling seems important for higher rate of hole closure.

Intra- and Inter-Rater Agreement of Anterior Lamina Cribrosa Depth Measurements Using Enhanced-Depth Imaging Optical Coherence Tomography.

PURPOSE: To determine intra- and inter-rater agreement of anterior lamina cribrosa depth (ALCD) manual measurements using enhanced-depth imaging optical coherence tomography (EDI-OCT). METHODS: Observational study. EDI-OCT of the optic nerve head was performed in healthy subjects. ALCD was defined as the perpendicular distance between the line connecting both edges of Bruch's membrane opening and the anterior border of the lamina cribrosa (LC), at the maximum depth point. Two experienced operators performed manual ALCD measurements of the LC independently, and one of the observers performed the same measurements twice. Intra- and inter-rater agreement was evaluated using intraclass correlation coefficients (ICC) and concordance correlation coefficients (CCC) for the right eye vertical (REV) and horizontal (REH) scans and left eye vertical (LEV) and horizontal (LEH) scans. RESULTS: 120 eyes of 61 subjects, with a mean age of 62.1 ± 15.0 years. The mean REV, REH, LEV and LEH ALCD were 456.2 ± 84.3, 444.5 ± 92.2, 436.7 ± 81.6, 427.6 ± 82.7 µm, respectively. ALCD intra- and inter-rater ICC and intra- and inter-rater CCC varied between 0.85-0.95, 0.84-0.93, 0.85-0.95 and 0.84-0.93, respectively. CONCLUSIONS: ALCD manual intra- and inter-rater measurements with EDI-OCT showed high agreement. EDI-OCT is a reliable tool for ALCD measurement, which can provide potentially useful information for integrated glaucoma management.

Real-world evaluation of RetCAD deep-learning system for the detection of referable diabetic retinopathy and age-related macular degeneration.

CLINICAL RELEVANCE: The challenges of establishing retinal screening programs in rural settings may be mitigated by the emergence of deep-learning systems for early disease detection. BACKGROUND: Deep-learning systems have demonstrated promising results in retinal disease detection and may be particularly useful in rural settings where accessibility remains a barrier to equitable service provision. This study aims to evaluate the real-world performance of Thirona RetCAD for the detection of referable diabetic retinopathy and age-related macular degeneration in a rural Australian population. METHODS: Colour fundus images from participants with known diabetic retinopathy or age-related macular degeneration were randomly selected from ophthalmology clinics in four rural Australian centres. Grading was confirmed retrospectively by two retinal specialists. RetCAD produced a quantitative measure (0-100) for DR and AMD severity. The area under the ROC curve (AUC) was calculated. Sensitivity, specificity, and positive and negative predictive values were calculated at a pre-defined cut-point of ≥50. RESULTS: A total of 150 images from 82 participants were included. The mean age (SD) was 64.0 (12.8) years. Seventy-nine (52.7%) eyes had evidence of referable DR, while 54 (36.0%) had evidence of referable AMD. The AUC for referable DR detection was 0.971 (95% CI 0.950-0.936) with a sensitivity of 86.1% (76.8%-92.0%) and a specificity of 91.6% (82.8%-96.1%) at the pre-defined cut-point. Using the Youden Index method, the optimal cut-point was 41.2 (sensitivity 93.7%, specificity 90.1%). The AUC for the detection of referable AMD was 0.880 (0.824-0.936). At the pre-defined cut-point sensitivity was 88.9% (77.8%-94.8%) and specificity was 66.7% (56.8%-75.3%). The optimal cut-point was 52.6 (sensitivity 87.0%, specificity 75.0%). CONCLUSION: RetCAD is comparable with but does not outperform equivalent deep-learning systems for retinal disease detection. RetCAD may be suitable as an automated screening tool in a rural Australian setting.

Gene and cell therapy for age-related macular degeneration: A review.

Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss among the elderly in Western communities, with an estimated global prevalence of 10 - 20% in people older than 65 years. AMD leads to central vision loss due to degeneration of the photoreceptors, retinal pigment epithelium and the choriocapillaris. Beckman's classification for AMD, based upon color fundus photographs, divides the disease into early, intermediate, and late forms. The late, vision-threatening stage includes both neovascular AMD and geographic atrophy. Despite its high prevalence and impact on patients' quality of life, treatment options for AMD are limited. While neovascular AMD can be medically managed with anti-VEGF intravitreal injections, until very recently there has been no approved treatment options for atrophic AMD; however, in February 2023 the first treatment for geographic atrophy - pegcetacoplan - was approved by the US FDA. We describe the current landscape of potential gene and cell therapeutic strategies for late-stage AMD, with an emphasis on the therapeutic options that might become available in the next few years.

Retinal vascular reactivity in carriers of X-linked inherited retinal disease - a study using optical coherence tomography angiography.

Purpose: Female carriers of X-linked inherited retinal diseases (IRDs) can show highly variable phenotypes and disease progression. Vascular reactivity, a potential disease biomarker, has not been investigated in female IRD carriers. In this study, functional optical coherence tomography angiography (OCT-A) was used to dynamically assess the retinal microvasculature of X-linked IRD carriers. Methods: Genetically confirmed female carriers of IRDs (choroideremia or X-linked retinitis pigmentosa), and healthy women were recruited. Macular angiograms (3x3mm, Zeiss Plex Elite 9000) were obtained in 36 eyes of 15 X-linked IRD female carriers and 21 age-matched control women. Two tests were applied to test vascular reactivity: (i) mild hypoxia and (ii) handgrip test, to induce a vasodilatory or vasoconstrictive response, respectively. Changes to vessel density (VD) and vessel length density (VLD) were independently evaluated during each of the tests for both the superficial and deep capillary plexuses. Results: In the control group, the superficial and deep VD decreased during the handgrip test (p<0.001 and p=0.037, respectively). Mean superficial VLD also decreased during the handgrip test (p=0.025), while the deep plexus did not change significantly (p=0.108). During hypoxia, VD and VLD increased in the deep plexus (p=0.027 and p=0.052, respectively) but not in the superficial plexus. In carriers, the physiologic vascular responses seen in controls were not observed in either plexus during either test, with no difference in VD or VLD noted (all p>0.05). Conclusions: Functional OCT-A is a useful tool to assess dynamic retinal microvascular changes. Subclinical impairment of the physiological vascular responses seen in carriers of X-linked IRDs may serve as a valuable clinical biomarker.

Early Pars Plana Vitrectomy in Acute Endophthalmitis: The Manchester Series.

BACKGROUND AND OBJECTIVE: Current literature lacks good-quality evidence regarding the outcomes of early pars plana vitrectomy (PPV) for acute exogenous endophthalmitis. The aim for this study was to analyze and discuss the outcomes of PPV for endophthalmitis in a UK tertiary hospital. PATIENTS AND METHODS: This study was a retrospective case series. The clinical records of consecutive patients who had PPV for acute exogenous endophthalmitis were reviewed. Demographic data, etiology, timing of onset, timing of PPV, intraand postoperative complications, baseline and final best-corrected visual acuity (BCVA), therapeutic regimens, and microbiology details were collected. Primary efficacy and safety outcome measures were BCVA improvement of two or more logMAR lines and intra- or postoperative complications, respectively. RESULTS: Forty-one patients with a median age of 76 (interquartile range, 64 to 82) years were studied. The most common etiology was intravitreal injection (41%), followed by phacoemulsification (34%). Median interval to PPV was 1.0 (interquartile range, 1.0 to 3.0) days. In a multivariate model controlling for age, baseline BCVA, microbiology positivity, and etiology (post-intravitreal injection), PPV after 24 hours was seven times more likely to achieve significant BCVA improvement (odds ratio, 7.47; 95% confidence interval, 1.12 to 49.66; P = .038). PPV within 24 hours of presentation was associated with more intraoperative complications. CONCLUSIONS: Favorable outcomes may be achieved with current antibiotic regimens and PPV for endophthalmitis. The series suggests that an early surgical intervention may be associated with poorer functional outcomes. Tap and inject at presentation, followed by a semi-urgent PPV as required, seems to be a sensible approach. [Ophthalmic Surg Lasers Imaging Retina. 2022;53:96-102.].

Trabeculectomy with mitomycin C alone or coupled with intracamerular bevacizumab? A 2-year comparative study.

PURPOSE: To compare outcomes of primary trabeculectomy using either mitomycin C (MMC) alone versus MMC augmented with intracamerular bevacizumab in patients with open-angle glaucoma. METHODS: Retrospective, cohort, two-centre, comparative study. Patients' data were screened between October 2015 and March 2019, with inclusion requiring a minimum follow-up of 24 months. Primary outcome was intraocular pressure (IOP) lowering at 24 months, with surgical success defined with different maximum IOP targets (≤18, ≤16 and ≤14 mm Hg) and at least 30% reduction and higher than 5 mm Hg. Absolute success was achieved if no IOP-lowering medication was needed and a qualified success if otherwise. Safety outcomes were analysed. RESULTS: A total of 110 eyes underwent trabeculectomy with MMC, 51 of these combined with intracamerular bevacizumab. Both strategies were effective in terms of IOP lowering (baseline vs 2 years postoperatively: 24.4 (8.0) mm Hg vs 12.1 (5.3) mm Hg in the MMC group; 25.1 (8.7) vs 10.8 (3.8) mm Hg in the MMC+bevacizumab group; p<0.001 in both comparisons). The MMC+bevacizumab group had a significant difference towards higher efficacy on absolute success rates at all targets (IOP≤14 or ≤16 or ≤18 mm Hg; p=0.010, p=0.039 and p=0.007, respectively). The large majority (93%) of the MMC+bevacizumab group was drop-free at 24 months, and 41% had IOP below 10 mm Hg. Complication rates were low and similar between groups, with no systemic adverse events. CONCLUSIONS: Intracamerular bevacizumab in MMC-augmented primary trabeculectomy increases the chances of obtaining low IOP outcomes. This strategy may be useful when planning for surgeries aiming at target pressures in the low teens. TRIAL REGISTRATION NUMBER: ISRCTN93098069.

MACULAR HOLE ASSOCIATED WITH TOXOPLASMOSIS: A SURGICAL CASE SERIES.

PURPOSE: There are currently limited data addressing the surgical outcomes of pars plana vitrectomy (PPV) in toxoplasmosis-related macular hole (tMH). We aim to report and discuss safety and efficacy of PPV for tMH. METHODS: Surgical case series (n = 11), with minimum postoperative follow-up time of 6 months. Consecutive patients who underwent PPV for tMH from 2013 to 2016 were included. Indications for surgery were: visual acuity ≥ 0.6 logarithm of the minimum angle of resolution (Snellen 20/80 or less), no intraocular inflammation for more than 6 months, extrafoveal toxoplasmosis scar, elevated tMH borders on optical coherence tomography, and patient agreement with surgery. Surgery was performed-PPV with epiretinal (if present) and internal limiting membrane peeling. Safety and efficacy of PPV for tMH were addressed by evaluating: 1) surgery-related complications and 2) visual acuity improvement. RESULTS: A total of 11 patients (6 male), with a mean age of 33.2 ± 11.0 years were studied. Mean preoperative best-corrected visual acuity significantly improved from 1.10 ± 0.24 (Snellen 20/252) to 0.43 ± 0.18 logarithm of the minimum angle of resolution (Snellen 20/54) at last follow-up visit (P < 0.01). The rate of visual acuity improvement (i.e., a gain of at least three lines) and tMH closure was 100% for both. The only reported surgery-related complication was cataract in one case. CONCLUSION: Our results suggest that PPV is a safe and effective option in tMH cases. A controlled, longitudinal study would contribute to confirm these findings.

Ultrasound Cyclo Plasty for Treatment of Surgery-Naïve Open-Angle Glaucoma Patients: A Prospective, Multicenter, 2-Year Follow-Up Trial.

BACKGROUND: The purpose of this prospective study was to evaluate the efficacy and safety of the Ultrasound Cyclo Plasty (UCP) procedure using high-intensity focused ultrasound in surgery-naïve open-angle glaucoma patients. METHODS: prospective, non-randomized, single-arm, multicenter clinical trial. Sixty-six eyes with primary open-angle glaucoma, intraocular pressure (IOP) ≥21 mmHg and with no history of filtering surgery were enrolled. Patients were treated by UCP with a therapy probe comprising six piezoelectric transducers, consecutively activated for 8 s each. Complete ophthalmic examination was performed before the procedure, 1 day after the procedure, and 1, 3, 6, 12, 18 and 24 months after the procedure. Primary outcomes were complete success (defined as IOP lowering from baseline ≥20% without additional glaucoma medications) and vision-threatening complications. Secondary outcomes were the presence of complications and the reduction of the number of medications used. RESULTS: IOP was significantly reduced after one procedure (p < 0.05), from a mean pre-operative value of 24.3 ± 2.9 mmHg (n = 2.3 hypotensive medications) to a mean value of 15.9 ± 3.6 mmHg (n = 2.2 hypotensive medications) at 2 years (mean IOP lowering of 33%). Surgical success was achieved in 74% of eyes. Notwithstanding side effects such as transient anterior chamber inflammation, refractive error changes, transient hypotony and macular edema, no major intra or post-operative complications such as phthisis, induced cataract, neovascularization or significant vision loss were observed. CONCLUSIONS: Ultrasound Cyclo Plasty is a valuable, effective and well-tolerated procedure to lower IOP in patients with open-angle glaucoma without previous filtering surgery.

Complete ILM Peeling Versus Inverted Flap Technique for Macular Hole Surgery: A Meta-Analysis.

BACKGROUND AND OBJECTIVE: To compare complete internal limiting membrane (ILM) peeling with the inverted flap technique for macular hole (MH) surgery. PATIENTS AND METHODS: An electronic database search on PubMed, CENTRAL, and ClinicalTrials.gov was performed. Inclusion criteria were comparative prospective/retrospective studies including patients with MH of any size with at least 6 months of follow-up. The primary outcome was MH closure rate. Secondary outcomes were best-corrected visual acuity improvement and surgery-related adverse events. RESULTS: Sixteen papers enrolling 1,403 eyes were included (733 ILM peeling, 670 inverted flap). MH mean minimum diameter and time of symptomatic evolution were higher in the inverted flap group (531.1 µm ± 188.8 µm vs. 602.8 µm ± 223.8 µm; 10.4 ± 20.2 months vs. 12.0 ± 18.4 months; P < .01). Overall, MH closure rate was superior with the inverted flap technique (risk-ratio [RR]: 1.25; 95% confidence interval [CI], 1.14-1.38; P < .0001), as well as in all subgroups: idiopathic large MH (n = 362; RR: 1.12; 95% CI, 1.05-1.20; P < .001), myopic MH without retinal detachment (n = 133; RR: 1.35; 95% CI, 1.14-1.59; P < .001), and MH retinal detachment (n = 198; RR: 1.89; 95% CI, 1.31-2.73; P < .001). CONCLUSION: This meta-analysis suggests the inverted flap technique is more effective in achieving MH closure. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:187-195.].

The effect of glaucoma treatment using high-intensity focused ultrasound on total and corneal astigmatism: a prospective multicentre study.

PURPOSE: Ultrasound cycloplasty (UCP) acts through the selective coagulation of the ciliary body using high-intensity focused ultrasound (HIFU) technology. The aim of this study was to investigate whether the application of ultrasound beams targeting the ciliary body using an external probe influences astigmatism. METHODS: Multicentre, prospective, single-arm, open-label study in adult patients with primary open-angle glaucoma and moderately uncontrolled intraocular pressure (IOP) under glaucoma medication. The primary outcome was induced corneal astigmatism, calculated from topography, and assessed statistically through vector analysis. Secondary outcomes included induced total astigmatism and mean changes from baseline in best-corrected visual acuity (logMAR) and IOP. Subgroup analysis was performed to assess the impact of device centring on corneal and total induced astigmatism. RESULTS: Fifty eyes were enrolled. Mean age was 69.6 ± 11.3 years. At 1, 3 and 6 months postprocedure, HIFU-induced corneal astigmatism was 0.88 D × 93°, 0.87 D × 106° and 1.16 D × 97°, respectively, while induced total astigmatism was 0.62 D × 103°, 0.42 × 106° and 0.39 × 107°. By the last follow-up, the percentage of patients with <0.50, <1.00, <1.50 and <2.00 D of induced corneal versus total astigmatism was 8.3% versus 46%, 29% versus 66%, 62.5% versus 88% and 79% versus 94%. Visual acuity was statistically significantly impaired at 1 month, but no difference remained by 3 and 6 months postprocedure. CONCLUSION: Ultrasound cycloplasty procedure is associated with increased corneal astigmatism. However, its impact on total refractive astigmatism is less pronounced.

XEN-augmented Baerveldt surgical success rate and comparison with the Ahmed Valve.

PURPOSE: The Baerveldt-XEN technique is intended to reduce the risk of early hypotony after Baerveldt implant, while keeping a good long-term intra-ocular pressure (IOP) control. The aim of this study is to discuss the surgical success rate of the Baerveldt-XEN and compare it with the commercially available flow-restrictor device (Ahmed glaucoma valve - AGV). METHODS: Single-centre, cohort study. Consecutive glaucoma patients with uncontrolled IOP > 21 mmHg on maximum tolerated medical therapy, and who had an aqueous shunt as the planned surgical procedure. Patients underwent implantation of Baerveldt-XEN. An age-, gender- and glaucoma aetiology-matched database of AGV patients was used for comparison. Complete surgical success was defined as a final IOP between 6 and 21 mmHg, and 20% reduction from baseline with no need for IOP-lowering medication. Qualified success was the same criteria but resorting to medications. RESULTS: Twenty-four eyes from 24 subjects with glaucoma were included in this study, 12 patients underwent Baerveldt-XEN implantation and 12 AGV. Twelve months after the Baerveldt-XEN implant, the IOP reduced from 33 ± 9 mmHg to 14 ± 3 mmHg (p < 0.001). The qualified and complete success rate was 50% and 25%, respectively. With the AGV, the IOP reduced from 29 ± 7 mmHg to 16 ± 7 mmHg (p = 0.001). The matched AGV group compared to the Baerveldt-XEN, presented a higher complete success rate (58.3%) and a qualified success rate of 33.3% (p = 0.72). No sight-threatening complications were recorded in both groups. CONCLUSIONS: The Baerveldt-XEN disclosed a low complete success rate at 1 year of follow-up, although with no major safety concerns. While studies with a longer follow-up are needed to demonstrate the potential advantages and disadvantages of the Baerveldt-XEN, this technique may be less likely to achieve drop-free efficacy when compared to other flow-restrictor strategies.

Optical coherence tomography angiography study of the retinal vascular plexuses in type 1 diabetes without retinopathy.

AIM: Previous data suggest the existence of retinal vascular changes and impaired autoregulation in the very early stages of diabetic retinopathy (DR). We compared the retinal plexuses between patients with type 1 diabetes (T1D) without DR and a demographically similar healthy cohort, using optical coherence tomography angiography (OCT-A). METHODS: Patients with T1D and no signs of DR were prospectively recruited from an outpatient clinic. Using OCT-A (AngioVue®), the parafoveal superficial (SCP) and deep (DPC) capillary plexus as well as the foveal avascular zone (FAZ) and perimeter were gathered. Mean comparison tests and linear regression analysis were used as statistical tests (STATA v14). RESULTS: Studied population included 48 subjects (24 T1D). The analysis of SCP revealed an attenuation of the capillary network compared with the control group in both parafoveal (51.8 ± 4.5 vs. 55.8 ± 3.2, p < 0.001) and perifoveal (51.9 ± 3.3 vs. 53.9 ± 1.9, p = 0.01) regions. A similar finding was observed in the DCP for both parafoveal (56.4 ± 4.3 vs. 60.4 ± 2.2, p < 0.001) and perifoveal (54.7 ± 3.9 vs. 60.8 ± 3.4, p = 0.001) sectors. Also, a longer time since T1D diagnosis was associated with a larger FAZ area (p = 0.055) and perimeter (p = 0.03). CONCLUSIONS: Significant differences in the retinal microvasculature were observed between healthy subjects and T1D patients using OCT-A, even before clinically detectable disease on fundus biomicroscopy.

Retinal Vascular Reactivity in Type 1 Diabetes Patients Without Retinopathy Using Optical Coherence Tomography Angiography.

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 (F1,23 = 15.69, P < 0.001 and F1,23 = 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 (F1,23 = 27.37, P < 0.0001 and F1,23 = 27.90, P < 0.0001, respectively). In the T1D group, this response was noted only in the deep plexus (F1,23 = 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.