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Christine N. Kay, Edwin M. Stone, Michael D. Abramoff; Increased Thickness Of Photoreceptor Outer Segments And Retinal Pigment Epithelium In Best Vitelliform Macular Dystrophy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1768.
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© ARVO (1962-2015); The Authors (2016-present)
Vitelliform material accumulation under photoreceptor outer segments and above retinal pigment epithelium (RPE) has been described in the macula of patients with Best vitelliform macular dystrophy and this material is believed to consist of outer segment debris. It is not clear whether the photoreceptors outside of fundoscopically visible lesions in Best vitelliform macular dystrophy are normal. In this pilot study we used automated optical coherence tomography (OCT) analysis to study the thickness of the photoreceptor outer segments and RPE in molecularly confirmed Best vitelliform macular dystrophy compared to control subjects in an extrafoveal location.
Fourteen subjects (26 eyes) with clinical diagnosis of Best vitelliform macular dystrophy and molecular confirmation of a mutation in the Best-1 gene (the John and Marcia Carver Nonprofit Genetic Testing Laboratory at the University of Iowa ) and ten control subjects (19 eyes) with normal outer retina were imaged using the Spectralis (Heidelberg, Germany) 3D volume scan protocol (6x6x2.2mm, 64 (y), 1048 (x) , 1024 (z) voxels. Using our validated fully 3D OCT segmentation algorithm, 11 intraretinal surfaces (1 corresponding to internal limiting membrane, 11 to Bruch’s membrane) were determined in all eyes, and photoreceptor equivalent thickness (PET), the thickness between surface 8 (photoreceptor inner segment/outer segment junction) to 11 (Bruch’s membrane) was determined in all A-scans averaging over itself and 4 neighbors. A single nasal A-scan location outside of the fovea, and outside of any deposits or outer retinal abnormalities, on the horizontal raphe, was manually selected in each eye. Mean PET for Best subjects and controls were calcuated and compared using t tests in Excel at a significance level of 0.05.
Automated PET measurement could be performed in all subjects. Patients with Best vitelliform macular dystrophy had mean PET = 56.23µm (95% Confidence Interval (CI), 53.64µm - 58.82µm) and control subjects had PET = 43.94µm (95% CI, 42.36µm - 45.52µm), an average difference of 12.3µm (p = 0.000000019).
The OCT equivalent of photoreceptor outer segments and RPE was 12.3µm thicker on average in patients with Best vitelliform macular dystrophy than in controls, outside of macroscopically visible lesions. The increased thickness of this region may reflect accumulation of outer segment debris. This may indicate that photoreceptor outer segments and RPE are affected in the macula in regions outside visible central lesions.
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