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Wendewessen Amde, Vinay A. Shah, Tamer H. Mahmoud; Effects Of Macular Ischemia On Post-operative Visual Acuity And Central Foveal Thickness After Pars Plana Vitrectomy For Proliferative Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):984.
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To evaluate the effects of macular ischemia on post-operative visual acuity and central foveal thickness after vitrectomy for proliferative diabetic retinopathy.
A retrospective interventional study included patients treated with pars plana vitrectomy for complications of proliferative diabetic retinopathy (PDR) by a single surgeon. The foveal avascular zone (FAZ) area was quantified for each patient from the preoperative fluorescein angiogram (FA). Spectral domain optical coherence tomography (SD OCT) scans with minimum signal strength of 6/10 acquired at least 3 months after surgery were evaluated to obtain foveal thickness data. Both automated central 1 mm subfield thickness (CFT) and manually-measured central foveal point thickness (CPT) were obtained. In addition, charts were reviewed for patient demographics, past medical history, use of peri-operative anti VEGF agent and complete ophthalmic examination including best corrected visual acuity (BCVA).
Complete data could be obtained for 21 eyes of 21 consecutive patients (mean age 48, range 24-63, 13 females). The mean preoperative FAZ area was 1.35mm2 +/-0.9 (range 0.62-3.24). The mean postoperative CFT and CPT were 236.1+/- 65.6 and 209+/-86.2 respectively. The mean logMAR visual acuity increased from 1.68+/-0.67 (20/800 snellen equivalent) to 0.62+/-0.58 (20/80 snellen) after vitrectomy (p<0.0001). There was a significant negative correlation between the preoperative FAZ area and the postoperative foveal thickness; between FAZ and CFT (r = -0.483, p = 0.0265) and between FAZ and CPT (r = -0.502, p = 0.0204). There was no significant correlation between preoperative FAZ area and postoperative BCVA. In addition, no significant correlation could be established between post-operative foveal thickness and post-operative BCVA.
A wider FAZ, which may indicate macular ischemia, is correlated with thinner foveal thickness after vitrectomy for complications of PDR. Visual function after diabetic vitrectomy may improve despite wider FAZ and thinner foveal thickness. Macular ischemia does not seem to have a good predictive value on visual outcome after vitrectomy for complications of PDR.
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