Quantitative analysis of retinal vessel attenuation in eyes with retinitis pigmentosa.

PURPOSE Retinal vessel attenuation is a key finding in the diagnosis of retinitis pigmentosa (RP), but there have been no studies to determine whether quantitative measurement of this retinal sign is useful. We aimed to investigate retinal vessel caliber and its relationship with the severity of RP. METHODS This is a cross-sectional study based on 74 patients (145 eyes) with RP who had visual field assessment with Goldmann permeter and good-quality retinal images for vessel size measurements identified by retrospective medial chart review (1973-2007) in the electrophysiology clinic of a tertiary eye hospital in Australia. Retinal vessel calibers were measured using a computer-based program as the central retinal artery and vein equivalent (CRAE and CRVE). Goldmann visual field area for III4e white test light was measured quantitatively using ImageJ software as a clinical parameter to indicate the severity of RP. We used the generalized estimating equation models to estimate the difference in retina vessel calibers accounting for correlation between right and left eyes. RESULTS Mean CRAE and CRVE were significantly narrower in persons with smaller visual field area. For each 100 cm2 decrease in visual field area, CRAE and CRVE decreased by -15.2 μm (95% confidence interval -20.7, -9.78) and -26.8 μm (-35.1, -18.5), respectively (both P<0.001). CONCLUSIONS In RP patients, the severity of visual field loss is correlated with retinal vessel attenuation. Quantitative retinal vessel caliber measurement may be a useful additional clinical marker for monitoring progression of RP or potential treatment response.