Fibrous proliferation of the pre-papillary canal in proliferative diabetic retinopathy: Cloquet?s canal as a scaffold for proliferative diabetic retinopathy

Abstract

The structure of the vitreous body is known to play an important role in the pathogenesis of proliferative diabetic retinopathy (PDR). The purpose of this study was to ascertain the pattern of fibrous membrane proliferation in PDR focusing on pre-optic disc canal-like fibrous proliferation. The investigation comprised two parts. The first, prospective study involved examining ten eyes of ten patients with PDR who underwent triamcinolone acetonide-assisted pars plana vitrectomy (TA-PPV). The presence of canal-like intravitreous structures was determined during TA-PPV. The second, retrospective study included analysis of photographs and clinical records of 235 eyes examined in 207 patients with PDR. The clinical and surgical records of the 235 eyes treated with PPV were reviewed and were categorized into four groups based upon the pattern of fibrous proliferation (optic disc type, pre-cortical pocket type, mixed type, or other). Each clinical feature was studied. The clinical features of the four groups of PDR were compared. A pre-optic disc canal-like structure was observed in seven of the ten eyes. In the retrospective study, 25 eyes (10.7%) were classified as optic disc type, 16 eyes (6.9%) as pre-cortical pocket type, 68 eyes (29.1%) as mixed type, and 126 eyes (53.4%) as other types. The patients with the optic disc type were significantly younger than the other three groups (P = 0.02). Other clinical features and post-operative outcome were not significantly different between the groups. A pre-optic disc canal-like structure, probably Cloquet's canal and the area of Martegiani, was present in PDR eyes. The PDR patients with fibrous proliferation of this structure were younger than those with other patterns of fibrous proliferation.