A Pilot Study of Fourier-Domain Optical Coherence Tomography of Retinal Dystrophy Patients

Abstract

Purpose-To characterize the macular anatomy of retinal dystrophy eyes using high-speed, highresolution, Fourier-domain optical coherence tomography (FD-OCT). Design-Case control study.Methods-Patients with retinal dystrophy and normal age and gender matched controls underwent FD-OCT imaging using the RTVue™ (Optovue, Inc.), which has an axial resolution of 5 microns. Vertical and horizontal eight mm scans of 1,024 lines/cross-section were obtained. Based on boundaries manually drawn on computer displays of OCT cross-sections, the thicknesses of the retina, inner retinal layer (IRL) and outer retinal layer (ORL) were averaged over both 5 and 1.5 millimeters regions centered at the fovea. The inner retina layer (IRL) was the sum of nerve fiber layer (NFL), ganglion cell layer (GCL) and inner plexiform layer (IPL) thicknesses. Total retinal thickness (RT) was measured between the inner edges of the NFL and the retinal pigment epithelium. Outer retinal layer (ORL) thickness was calculated by subtracting IRL thickness from RT.Results-14 patients (7 retinal dystrophy patients and seven normal controls) underwent high resolution OCT imaging. Patients ranged in age from 33 to 84 years old. Retinal dystrophy diagnoses included retinitis pigmentosa (3), cone-rod degeneration (2), and Stargardt disease (2). The following thickness values reported are mean ± standard deviation. Mean foveal RT (foveal RT) averaged over a 1.5 mm area was 271.3+/-23.3μ for normal patients and 159.2+/-48.0 μ for dystrophy (p<0.001) patients. Mean macular RT (macular RT), averaged over the central 5-mm area, was 292.8+/-8.1 μ for normal patients and 199.1+/-32.7μ for dystrophy patients (p<0.001). Mean macular IRL was 109.9 ± 6.4 for normals and 98.0 +/-20.6μ for dystrophy patients (p=0.02); mean macular ORL was 182.9+/-4.7 μ for normals and 101.1+/-18.8μ for dystrophy patients (p<0.001).Conclusion-Eyes with retinal dystrophy had a small (11%) decrease in macular IRL and severe (45 %) decrease in macular ORL compared to normals. The higher resolution and definition of the FD-OCT technology facilitated measurements of the thickness of retinal sublayers.

Optical coherence tomography in progressive cone dystrophy

“…While benefits of OCT in diagnosing most of the macular disorders have been assessed in numerous studies, only a few studies mention OCT findings in PCD. OCT findings in cone-rod dystrophy have only been described by Wolfing et al 16 in 1 patient, Lim et al 15 in 2 patients and Emfietzoglou et al 17 in 1 patient. To date, no OCT findings have been published in a larger group of patients with PCD.…”

“…Visual acuity (VA) in the affected individuals is usually normal during childhood and only gradually deteriorates, often leading to legal blindness. Impaired VA is accompanied by a defective colour sense, visual field defects, photophobia 1,2,[4][5][6][7][8][9][10][13][14][15] and in some patients with affected rods also by nyctalopia 3,6,7,9 . Visual field defects include central scotomata 1,3,6,9,12,13 , annular scotomata around the centre 1,3 , diffuse reduction in sensitivity 12 and rarely, peripheral scotomata [1][2][3]6,9 .…”

“…A finding in the macula may vary within the range of non-specific changes to the retinal pigment epithelium (RPE), to the characteristic RPE lesions of the bull's eye type [1][2][3][4][5][6][7]9,[13][14][15] . Changes in the macula are rarely accompanied by the temporal disc pallor 1,3,4,6,[12][13][14] , golden tapetal sheen 8,12 , white dot-like lesions at the level of RPE mostly in the mid-periphery 1,3 , pigment shifts in the periphery 1,3,6,9,15 and nystagmus 2,4,6,9,11,14 .…”

“…Changes in the macula are rarely accompanied by the temporal disc pallor 1,3,4,6,[12][13][14] , golden tapetal sheen 8,12 , white dot-like lesions at the level of RPE mostly in the mid-periphery 1,3 , pigment shifts in the periphery 1,3,6,9,15 and nystagmus 2,4,6,9,11,14 . Electrophysiological examinations show clear reduction in or even elimination of the cone function with normal or reduced response of the rods.…”

“…Electrophysiological examinations show clear reduction in or even elimination of the cone function with normal or reduced response of the rods. ERG changes precede the decline in subjective visual functions [1][2][3][4][5][7][8][9][10][11][13][14][15] . The forms of progressive dystrophy with functional deficiency limited to the photopic system are termed progressive cone dystrophy 2,6 .…”