Influence of Cataract on Retinal Nerve Fiber Layer Measurements in Time-Domain and Spectral-Domain Optical Coherence Tomography

Abstract

Purpose: : To assess and compare the influences of cataract on retinal nerve fiber layer (RNFL) thickness measurements between Stratus time-domain (TD) optical coherence tomography (OCT) and Cirrus spectral-domain (SD) OCT.

Methods: : Patients who underwent uneventful cataract surgery without any other pathologic conditions were consecutively included in this study. All eyes underwent peripapillary RNFL thickness measurement before and 8 weeks after cataract surgery with Stratus TD-OCT and Cirrus SD-OCT on the same visit. Change in RNFL thickness measurement and signal strength (SS) after cataract surgery was evaluated with Stratus TD-OCT and Cirrus SD-OCT.

Results: : A total of 54 patients (54 eyes) were enrolled. After 19 eyes being excluded either due to poor image or low SS (<5), scans of 35 eyes of 35 patients were included for final analysis. Statistically significant difference was found between preoperative and postoperative SS in Cirrus SD-OCT but not in Stratus TD-OCT (paired t test, p= 0.002 and 0.789, respectively) in all participants. In Stratus TD OCT, peripapillary RNFL thickness measurements of post-cataract surgery were thicker than measurements of pre-cataract surgery in average RNFL, temporal quadrant, and 8 to 10 o’clock hour map. In Cirrus SD OCT, all RNFL, average, clock hour, and quadrant RNFL thickness measurements, except for temporal quadrant and 4 to 6 o’clock hour, were significantly thicker in measurement after cataract surgery. In eyes with predominant cortical opacity (n=20), average RNFL thickness measurements in both OCTs and SS in Cirrus SD-OCT were found to be significantly increased after cataract surgery. There was significant correlation between perioperative RNFL thickness and SS changes in both Stratus TD-OCT (r²=0.410, p<0.001) and Cirrus SD-OCT (r²=0.246, p=0.002).

Conclusions: : Our data suggest that the presence of cataract significantly affect RNFL thickness measurements by Cirrus SD-OCT and Stratus TD-OCT. Cirrus OCT being more vulnerable to media opacity does not necessarily mean lower RNFL thickness measurement performance in cataract as more subjects with cataract were excluded because of either poor quality or low SS of scan of Stratus OCT than Cirrus OCT.

Keywords: cataract • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)