Abstract
Purpose: :
To assess the correlation between retinal morphology and function in patients with retinitis pigmentosa (RP) using spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence (AF) imaging and microperimetry (MP).
Methods: :
Twelve unrelated patients with RP who had hyperautofluorescent parafoveal ring were tested. In all patients, full ophthalmological examination, static and kinetic (0 dB, 4 dB, 8 dB, 16 dB) MP (MP1 Microperimeter, Nidek Technologies, Padova, Italy), OCT (3D OCT-1000, Topcon Inc, NJ, USA) and AF imaging (HRA, Heidelberg Engineering, Heidelberg, Germany) were performed. The results of OCT and AF imaging were superimposed on the results of MP testing.
Results: :
A high correlation between retinal sensitivity and retinal thickness was observed (r = 0.43, P = 0.0007). The mean retinal sensitivity over the encircled area of normal AF (12.2 dB, CI 6.6 to 11.9) was significantly higher (F = 66.3, P < 0.0001) than the mean retinal sensitivity of the hyperautofluorescent ring (2.4 dB, CI 1.1 to 3.8) and the area outside of the ring (0.5 dB, CI 0 to 2.1). Photoreceptor layer on the site where kinetic stimuli were identified was better preserved and thicker for lower intensities than higher intensities of the stimuli (F = 76, P < 0.0001). On the site of the hyperautofluorescent ring, the integrity of the photoreceptor layer was affected and the inner segment/outer segment line was absent.
Conclusions: :
The sensitivity of the retina correlates with retinal thickness. Low intensity (16 dB) stimuli are seen only where photoreceptor layer is still preserved. On the other hand, high intensity stimuli (0 dB) could be seen even in complete loss of the photoreceptor layer. Hyperautofluorescent ring demonstrates the border of abnormal retinal morphology and function making AF imaging a clinically significant test for assessing the severity and progression of dysfunction in affected individuals with RP.
Keywords: imaging/image analysis: clinical • retinal degenerations: hereditary