Ravi Krishna Nrusimhadevara

Internal limiting membrane peeling for decompression of macular edema in retinal vein occlusion: a report of 14 cases.

Background: Currently, there is no proven treatment for macular edema due to central retinal vein occlusion (CRVO). Moreover, not all cases with macular edema due to branch retinal vein occlusion (BRVO) respond to laser photocoagulation. We postulated that internal limiting membrane (ILM) peeling for decompression of macular edema in cases of retinal vein occlusion would facilitate egress of blood and extracellular fluid out of the inner retinal layers, leading to reduction of macular edema and improvement in visual acuity. Methods: Fourteen consecutive patients with macular edema due to CRVO or selected cases of BRVO, not eligible for laser photocoagulation, underwent pars plana vitrectomy with removal of preretinal hyaloid and peeling of the ILM stained with indocyanine green dye. Results: In all cases, intraretinal blood and retinal thickening diminished within 6 weeks of surgery. Visual acuity improved in 78.6% of cases. No surgical complications occurred, although one patient developed nuclear cataract 10 months postoperatively. Conclusion: Pars plana vitrectomy with ILM peeling in selected cases of CRVO and BRVO showed improvement in visual acuity in this nonrandomized, noncontrolled study. This pilot study adds support to the concept that ILM peeling may of visual benefit when compared with the natural history in these vaso-occlusive diseases.

Retinal Arteriolar Hemodynamic Response to a Combined Isocapnic Hyperoxia and Glucose Provocation in Early Sight-Threatening Diabetic Retinopathy

PURPOSE To quantify the magnitude of change of retinal arteriolar hemodynamics induced by a combined isocapnic hyperoxia and glucose provocation in diabetic patients with early sight-threatening diabetic retinopathy (DR) and in age-matched control subjects and to compare the response to that of an isocapnic hyperoxia provocation alone. The study hypothesis was that hyperglycemia reduces the retinal vascular reactivity response to a hyperoxic stimulus. METHODS The sample comprised 17 control subjects (group 1), 15 patients with no clinically visible DR (group 2), 16 patients with mild-to-moderate nonproliferative DR (group 3), and 15 patients with diabetic macular edema (group 4). Retinal hemodynamic measurements were acquired in the subjects, at baseline and 1 hour after consuming a standardized oral glucose load drink while breathing oxygen isocapnic with baseline. RESULTS Retinal blood velocity and flow significantly decreased in all groups (P < or = 0.001 and P < or = 0.0002, respectively) in response to a combined isocapnic hyperoxia and glucose provocation. The maximum-to-minimum velocity ratio significantly increased (P < or = 0.005), and wall shear rate (WSR) significantly decreased (P < or = 0.0002), in groups 1, 2, and 3, but not in group 4. The vascular reactivity response was not significantly different across the groups. The control group demonstrated a reduced change in flow (P = 0.009) and WSR (P = 0.010) to the combined isocapnic hyperoxia and glucose provocation compared with that of hyperoxia alone. CONCLUSIONS The vascular reactivity response to a combined isocapnic hyperoxia and glucose provocation produced a pronounced reduction in blood flow. Unlike the response to hyperoxia alone, the vascular reactivity response was not significantly different across the groups. Hyperglycemia reduced the retinal vascular reactivity response to hyperoxia in age-matched control subjects.