Pars plana vitrectomy for diabetic macular oedema: OCT and functional correlations JI Patel 1,2 , PG Hykin 1 , M Schadt 1 , V Luong 2 , F Fitzke 2 and ZJ Gregor 1 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 low- elevation profile of the thickened macula (P ¼ 0.007). Conclusions In this prospective study of PPV for persistent fovea-involving CSMO there was structural and functional improvement. Eye (2006) 20, 674–680. doi:10.1038/sj.eye.6701945; published online 21 October 2005 Keywords: diabetes; macular oedema; pars plana vitrectomy; OCT Introduction Diabetes mellitus is the leading cause of blindness in the working population in the developed world and diabetic macular oedema (DMO) accounts for 72% of registrable blindness among patients with diabetes mellitus. 1 In all 9% of the diabetic population develop oedema within one disc diameter (DD) of the fovea and 40% of those have central macular involvement. 2 The natural history of DMO is one of progressive visual loss with more than 50% of patients losing two or more lines of visual acuity within 2 years. 3 At present there are only two proven modalities of management: strict control of systemic blood glucose and blood pressure has been shown to delay the onset and to reduce the progression of diabetic retinopathy for both Type I and Type II diabetes mellitus. 4,5 The second is the timely use of photocoagulation of the perifoveal retina. 6 The results of the Early Treatment Diabetic Retinopathy Study (ETDRS) showed that laser treatment mostly stabilised vision and reduced the risk of moderate visual loss by 50%. However, only 3% of the patients improved by three or more lines of vision by the end of that study. Lewis was the first to describe a positive effect of pars plana vitrectomy (PPV) on diabetic patients who had a thickened and taut posterior hyaloid membrane with traction on the macula. There were improvements in both vision and resolution of macular oedema 7 and the Received: 23 August 2004 Accepted: 15 April 2005 Published online: 21 October 2005 1 Moorfields Eye Hospital, London, UK 2 Department of Pathology, Institute of Ophthalmology, London, UK Correspondence: JI Patel, Department of Pathology, Institute of Ophthalmology, 11-43 Bath St., EC1V 9EL London, UK Tel: þ 44 207 608 6808; Fax: þ 44 207 608 6862. E-mail: jigs37@ hotmail.com Eye (2006) 20, 674–680 & 2006 Nature Publishing Group All rights reserved 0950-222X/06 $30.00 www.nature.com/eye CLINICAL STUDY