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L. H. Lima, W. Cella, L. Yannuzzi, V. Greenstein, S. Tsang; Structural Integrity of Photoreceptor Cilia Underlying the Hyperfluorescent Ring in Patients With Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2009;50(13):990.
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© ARVO (1962-2015); The Authors (2016-present)
In the macula of a patient with retinitis pigmentosa (RP) an abnormal ring of increased autofluorescence (AF) surrounding the fovea is frequently observed, but its origin is unclear. Thus, we decided to analyze the retinal layers underlying the hyperautofluorescent ring visible on fundus AF (FAF) in RP patients.
Sixteen eyes of 8 RP patients, aged 22-56 years, were studied. All tested eyes had best corrected visual acuities of 20/20. FAF imaging was performed with a confocal scanning laser ophthalmoscope (Heidelberg HRA II imaging system). The structure of the retinal layers, underlying the hyperautofluorescent ring, was analyzed with high resolution spectral domain optical coherence tomography (SD-OCT).The images of the hyperautofluorescent ring were superimposed on the SD-OCT horizontal line scans using an imaging registration program written in MatLab. The integrity of the photoreceptor cilia also known as the inner/outer segment (IS/OS) junction of the photoreceptors, the outer nuclear layer (ONL), and retinal pigment epithelium (RPE) were evaluated outside, across and within the ring.
Fourteen eyes showed abnormal hyperautofluorescent parafoveal rings on FAF. The diameter of the ring along the horizontal axis ranged from 2369 um to 7405 um, and it ranged from 1776 um to 6720 um along the vertical axis. In the foveal area, FAF did not detect any abnormalities. Outside the ring, FAF revealed hypoautofluorescence compatible with photoreceptor/RPE dysfunction. SD-OCT within the ring, in the area of normal foveal FAF, revealed intact retinal structure in all eyes and total retinal thickness values that were within normal limits. Across the ring, IS/OS junction disruption was observed and the ONL was decreased in thickness in a centrifugal direction in all eyes. Outside the hyperautofluorescent ring, the IS/OS junction and the ONL appeared to be absent and there were signs of RPE degeneration. Total retinal thickness was decreased compared to control eyes.
The parafoveal hyperautofluorescent ring seen on FAF in RP patients is associated with IS/OS junction loss. The hyperautofluorescent ring can be a prognosticating factor in monitoring RP.
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