Materials and Methods: Seventy-four eyes of 43 patients were included in this study. The eyes were divided into Group 1 (40 eyes of 23 patients with NPDR) and Group 2 (34 eyes of 20 patients with PDR). Group 2 was further divided into Group 2a (18 eyes with good prognosis) and Group 2b (16 eyes with unfavorable prognosis) according to the severity of proliferations and response to therapy. The quantitative optic disc parameters were evaluated using HRT II, and were compared by Mann-Whitney U test and t-test. Statistical significance was set as p<0.05.

Results: The demographic characteristics of all the groups were similar (p>0.05). The disc area in Group 1 was significantly larger and the rim area was smaller than those in Group 2 (p=0.001, p=0.002, respectively). Mean cup volume, cup area, cup depth, rim volume, and cup-to-disc ratio were similar in all groups (p>0.05).

Conclusion: A large optic disc area may be a predisposing factor for the development of PDR. However, neovascularization and edema of the optic disc may also lead to calculation errors. A definite conclusion should not be made until further prospective controlled studies comparing optic disc parameters in eyes with diabetic retinopathy are conducted. Keywords : Diabetic retinopathy, Heidelberg Retinal Tomography, neovascular proliferation, optic disc topography.