REPRODUCIBILITY OF RETINAL NERVE-FIBER LAYER EVALUATION BY DYNAMIC SCANNING LASER OPHTHALMOSCOPY

Scanning laser ophthalmoscopy is a laser-based image acquisition techn ique, which greatly improves the quality of the examination of the fun dus and the retinal nerve fil;er layer. To assess retinal nerve fiber layer imaging by scanning laser ophthalmoscopy and evaluate intra- and interobserver reproducibility in the classification of retinal nerve fiber layer defects, three independent observers evaluated on two sepa rate occasions the videotaped images of 150 eyes of 80 consecutive pat ients with ocular hypertension or glaucoma. Ophthalmoscopy was perform ed using argon blue light (488 nm), confocal apertures of 3 to 1 mm, a nd 40-degree and 20-degree field angles. Of 150 eyes, 20 (13.3%) were excluded from the study because of the poor quality of the images (cli nically significant cataract or myopic peripapillary atrophy). The ret inal nerve fiber layer was evaluated qualitatively according to a stan dard classification: normal pattern, slit, wedge, and diffuse defects. Intraobserver reproducibility, evaluated by kappa statistic, was exce llent (greater than or equal to 0.75): observer A = 0.78 (95% confiden ce limits, 0.67-0.88); observer B = 0.84 (95% confidence limits, 0.72- 0.96); and observer C = 0.79 (95% confidence limits, 0.67-0.91). Inter observer reproducibility was also excellent in all cases: observers A- B = 0.84 (95% confidence limits, 0.71-0.98); observers A-C = 0.76 (95% confidence limits, 0.65-0.87); and observers B-C = 0.80 (95% confiden ce limits, 0.69-0.92). Kappa values ranged between 0.59 and 0.69 for i ntraobserver reproducibility and between 0.55 and 0.69 for interobserv er reproducibility when using only those eyes in which abnormalities w ere noted by at least one observer. Retinal nerve fiber layer examinat ion by means of argon blue scanning laser ophthalmoscopy proved to be clinically;suitable in a high proportion of patients and reliable in t erms of the identification of defects.