Pars plana vitrectomy for diabetic macular oedema: OCT and functional correlations

Abstract

Purpose A prospective study to evaluate the macular structural and functional effects of pars plana vitrectomy (PPV) for persistent diffuse clinically significant macular oedema (CSMO). Method A total of 12 patients with persistent diffuse CSMO were recruited and underwent assessment including best-corrected visual acuity, fundus fluorescein angiography, optical coherence tomography (OCT) and fine matrix mapping (FMM) at baseline and over a period of a year poststandard three-port PPV. Results The median baseline ETDRS letters score for all 12 patients was 52 (range 41-63) while at 12 months it had increased to 65 (range of 27-68), an improvement of two complete ETDRS lines (P ¼ 0.037). Similarly, there was an improvement in the perifoveal cone thresholds (P ¼ 0.02). The foveal thickening for all 12 patients ranged from a median of 183 to 751 lm (normal range 126-180 lm) and the macular volume ranged from a median of 2.13 to 6.42 mm 3 (normal o1.66 mm 3 ). After surgery, both the median foveal thickness (from 334 to 280 lm) and median macular volume (from 3.24 to 2.61 mm 3 ) demonstrated decreases over 12 months (P ¼ 0.01). On baseline OCT, the patients fell into two anatomically distinct groups: Group 1 (n ¼ 4) had a dome-shaped thickened macula with a partial posterior hyaloid separation and a significantly higher foveal thickness and macular volume than Group 2 (n ¼ 8) which had a diffuse lowelevation profile of the thickened macula (P ¼ 0.007).

Quantitative Assessment of Photoreceptor Layer in Eyes with Resolved Edema after Pars Plana Vitrectomy with Internal Limiting Membrane Removal for Diabetic Macular Edema

“…Earlier studies involving OCT mostly focused on macular edema and a correlation was found between visual acuity (VA) and reduction in central macular thickness [7,8,9,10,11,12]. However, some eyes with DME have a poor visual outcome despite resolution of macular edema after successful treatment [13,14,15,16,17,18].…”

Macular Edema Surgical Treatment

“…Therefore, vitrectomy has been reported to be beneficial in these situations. Some studies, however, have shown that vitrectomy is effective even when there is no evidence of macular traction [18][19][20][21] . Perhaps this is due to removal of the posterior hyaloid also removes toxic substances, such as histamine, free radical scavengers, and VEGF, which may be harbored in the preretinal space [22] .…”

Optical Coherence Tomography Findings in Diabetic Macular Edema

“…However, OCT is becoming the mainstay of objective treatment monitoring and follow-up of patients with macular edema. It is widely accepted in trials and studies (DRCRN, 2010;Estabrook et al, 2007;Otani & Kishi, 2000;Patel et al, 2006), as well as in clinical settings.…”

“…Macular traction is a factor implemented in the pathogenesis of macular edema and there is increasing evidence that releasing it via vitrectomy may be beneficial (DRCRN, 2010;Patel et al, 2006;Yanyali et al, 2007). Macular traction may be induced by vitreoretinal interface abnormalities such as incomplete posterior vitreous detachment (PVD) or ERM.…”