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Correlations between spectral-domain OCT measurements and visual acuity in cystoid macular edema associated with retinitis pigmentosa.

PURPOSE
To evaluate the characteristics of spectral-domain optical coherence tomography (SD-OCT) findings associated with visual outcome and compare OCT measurements according to presence of cystoid macular edema (CME) in retinitis pigmentosa (RP) patients.


METHODS
Patients with typical RP who underwent SD-OCT were included. We compared OCT measurements such as central retinal thickness (CRT), photoreceptor thickness, and photoreceptor inner segment/outer segment (IS/OS) junctional status at the fovea between the CME and non-CME groups. Also, correlations between best-corrected visual acuity (BCVA) and each parameter were determined.


RESULTS
Among a total of 220 eyes in 128 RP patients, 46 eyes of 30 patients (20.9%) had CME. CRT was 303.1 ± 81.8 μm and 209.2 ± 46.8 μm in the CME and non-CME groups, respectively (P < 0.001). BCVA did not differ between the two groups (P = 0.690). However, among a subgroup with unilateral CME, BCVA was significantly worse in CME eyes than in the fellow eyes (P = 0.046). In the CME group, eyes with increased CRT showed worse BCVA (P = 0.010). Among 12 eyes with severe CME, defined as 350 μm or more CRT, 10 (83.3%) showed an absent IS/OS junction. In the non-CME group, in contrast, eyes with decreased CRT showed worse BCVA (P < 0.001). In both groups, severe IS/OS disruption was correlated with worse BCVA (P < 0.001). The risk of IS/OS disruption was higher in the CME group (P = 0.016).


CONCLUSIONS
The presence of CME in RP patients was not necessarily correlated with loss of visual acuity. In eyes with CME, however, severe CME was strongly correlated with IS/OS disruption and visual impairment. Thus, severe CME seemed to be a predictor of poor visual outcome in RP patients.