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.