EFFECT OF OPTIC-NERVE HEAD DRUSEN ON NERVE-FIBER LAYER THICKNESS

Objective: The purpose of the study was to evaluate the effect of opti c nerve head drusen (ONHD) on nerve fiber layer (NFL) thickness by vis ual field testing, red-free photography of NFL, and optical coherence tomography (OCT). Design: The study design was a prospective clinical study. Participants: Twenty-three eyes of 15 consecutive patients with ONHD and 27 eyes of 27 age-matched control subjects participated. Int ervention: Ophthalmologic examination. color and red-free photography, automated Humphrey visual field testing, and OCT were performed. Each of the drusen study eyes were graded on a scale of 0 to III based on the amount of visible ONHD. Grade 0 represented the absence of clinica lly visible ONHD, and grade III represented an optic nerve head with a bundant drusen. Main Outcome Measures: Findings from clinical evaluati on and color optic nerve head photographs and NFL evaluation by red-fr ee photography, visual fields, and OCT were measured. Results: The num ber of study eyes with visual field defects increased with the higher grade drusen discs, corresponding both with progressively thinner NFL measurements by OCT and NFL loss shown by NFL photography. The NFL eva luation showed NFL thinning by red-free photography in 12 (71%) of 17 eyes with visible drusen (grades I-III discs) and visual field defects in 9 (53%) of 17 eyes in this group. By OCT measurements, the superio r and inferior NFLs were significantly thinner in the eyes with visibl e ONHD compared with those of control eyes in the superior quadrant (P < 0.001) and inferior quadrant (P = 0.004). Compared with grade 0 dis cs, grades I through III discs showed statistically significant thinni ng of the NFL superiorly (P < 0.001). No statistical significant thinn ing of the NFL was seen in grade 0 discs compared with those of contro l subjects. Conclusions: Optical coherence tomography is able to detec t NFL thinning in eyes with ONHD and appears to be a sensitive and ear ly indicator of NFL thinning. Increased numbers of clinically visible ONHD correlated with NFL thinning shown by OCT measurements and both v isual field defects and NFL loss seen by red-free photography.