Retinal Nerve Fiber Layer Thickness Measurement Repeatability for Cirrus HD-OCT Retinal Tracking System During Eye Movement.

PURPOSE: To investigate the repeatability of peripapillary retinal nerve fiber layer (RNFL) thickness measurements obtained using Cirrus high-definition optical coherence tomographic (Cirrus HD-OCT) retinal tracking system during various types of eye movements.
MATERIALS AND METHODS: We included 20 healthy eyes, 40 glaucomatous eyes of elderly patients, and 17 eyes with pathologic nystagmus. For healthy eyes, RNFL thickness measurements were obtained under 3 conditions: (1) without eye movement, fixated on the device's internal target, (2) with horizontal eye movement, and (3) with vertical eye movement during scan acquisition. Each session was performed 3 times with and without the use of the retinal tracking system. The repeatability of RNFL thickness measurements obtained with and without the retinal tracking was compared within each session and among the sessions.
RESULTS: In healthy eyes, measurements obtained without the use of a retinal tracking system showed lower repeatability when measurements were obtained with eye movements than without (P<0.05). However, when retinal tracking system was used, measurement repeatability under conditions with eye movements was similar to that achieved without eye movement (P>0.05) and higher than that obtained without the use of a retinal tracking system (P<0.05). In elderly glaucomatous patients, the retinal tacking system did not significantly improve measurement repeatability during fixation (P>0.05). In eyes with pathologic nystagmus, the tracking system did not follow eye movement and scan acquisition was not processed.
CONCLUSIONS: Cirrus HD-OCT retinal tracking system may enhance RNFL thickness measurement repeatability under certain, but not all, eye movement conditions.