Confocal scanning laser tomography of the optic nerve head of glaucoma patients: inter-correlation of disc parameters.

OBJECTIVE To evaluate the scanning laser tomography characteristics of the optic nerve head in patients with primary open angle (POAG) glaucoma using the Heidelberg retina tomography (HRT II). DESIGN A clinic-based retrospective study. PARTICIPANTS A total of 84 eyes of 42 POAG patients with good quality HRT II Images were studied at Charles Nicolle Hospital University department of Ophthalmology out-patient clinic, Tunis. METHODS Characteristics of optic disc pattern of glaucoma patients were documented using the HRT II. Association of disc area with the other HRT parameters and inter-eye difference in the HRT parameters were assessed using simple and multiple regression analysis. MAIN OUT-COME MEASURES: Disc area, cup area, rim area, cup-to-disc area ratio, cup volume, rim volume, mean cup depth, maximum cup depth and mean retinal nerve fibre layer thickness. RESULTS Twenty-seven males and 15 females were studied. The mean age of glaucoma patients was 48.9±2.7 years. The mean disc area, cup area, cup-to-disc area ratio and rim area were 2.19±0.46 (range, 1.23 - 3.16mm2), 0.95±0.94 (range 0.08 - 2.15), 0.42±0.21(range 0.004-0.92), 1.25± 0.46 (range 0.18-2.64) respectively. Disc area was positively correlated to the cup area (p=0.001), rim area (p=0.001), cup to disc area ratio (p=0.03), and mean cup depth (p=0.02).The glaucoma diagnosis score was strongly correlated with the rim area (p< 0.001), cup area (p< 0.001), mean cup depth (p< 0.001) and cup disc area ratio (p< 0.001). Absolute inter eye parameter between the two eyes were positively correlated with disc area (p< 0.05). CONCLUSIONS There was a significant correlation of the parameters between the two eyes and between the disc area and some other HRT parameters.