Retinal nerve fiber layer analysis in RP patients using Fourier-domain OCT

Abstract

Purpose: To determine peripapillary retinal nerve fiber layer thickness (RNFL) abnormalities in patients with retinitis pigmentosa (RP) using Fourier-domain optical coherence tomography (Fd-OCT) and to evaluate the potential effect of cystoid macular edema (CME) or axial length on RNFL measurements in such patients.

Methods: Ninety-seven eyes of 52 patients with diagnoses of retinitis pigmentosa or Usher syndrome type II underwent complete ocular examination. Peripapillary RNFL thickness was measured using Fd-OCT in 16 segments from 4 quadrants--temporal (316 degrees -45 degrees ), superior (46 degrees -135 degrees ), nasal (136 degrees -225 degrees ), and inferior (226 degrees -315 degrees ). These measurements were compared with age- and disc size-adjusted control values. Further analyses were performed to determine the correlation of axial length or CME with RNFL thickness.

Results: Thinning of the RNFL was observed in 37 eyes (38.14%) of 23 patients (44.23%). A maximum number of eyes had thinning in the nasal quadrant followed by the inferior quadrant; the superior and temporal quadrants were abnormally thin in fewer eyes. No correlation was found between axial length and RNFL thickness in the total cohort (correlation coefficient, 0.039). An abnormal increase in RNFL thickness was observed in 21.65% eyes, but no association was found between the presence of CME and increased RNFL thickness.

Conclusions: RP eyes may show abnormal thinning or increased thickness of RNFL measurements on testing with Fd-OCT. RNFL defects observed by OCT testing document the presence of anatomic defects in more anterior structures within the retina in a notable number of patients with RP.