Atlas of Ophthalmology

Rod and Cone Photoreceptor Degeneration Associated With Long-term Chloroquine Use (OCT, Adaptive Optics)

Retina -> Toxic Retinopathies; see also Light Toxicitiy
52 years of age, male, BCVA RA cc 0.1, LA cc 0.1. Major symptoms: The presenting symptom was difficulty with reading. General medical history: Use of chloroquine was due to lupus erythematodes. The duration of hydroxychloroquine therapy was 15 years with a daily dosage of hydroxychloroquine of 250 mg per day (1993-2008). Ocular medical history: Decreasing visual acuity, perifoveal ophthalmoscopic pigmentary changes, and bilateral perifoveal defects. Purpose: To describe spectral-domain optical coherence tomography (SD-OCT) and adaptive optics (AO) imaging in a patient with long-term hydroxychloroquine therapy, using SD-OCT (HE, Spectralis OCT) and AO (rtx1, Imagine Eyes).The area of interest of AO imaging was outside the perifoveal ophthalmoscopic pigmentary changes. Findings 1) OCT: Inside the perifoveal ophthalmoscopic pigmentary changes Spectral OCT revealed an impairment of outer nuclear layer, external limoting membrane, junction of the inner and outer photoreceptor segment layers (IS/OS), and retinal pigment epithelium layer. In this area SD-OCT images demonstrated loss of photoreceptor inner segment/outer segment (IS/OS) junction and a downward displacement of inner retinal structures. Outside the perifoveal ophthalmoscopic pigmentary changes SD-OCT images demonstrated only a weak impairment of outer nuclear layer, external limoting membrane, and junction of the inner and outer photoreceptor segment layers (IS/OS), 2) AO: Outside the perifoveal ophthalmoscopic pigmentary changes AO image showed a massive degeneration of the rod and cone photoreceptor mosaic. AO detected strong abnormalities caused by chloroquine toxicity. Discussion: In general chloroquine is considered to damage directly photoreceptor cells most severely also in areas with no ophthalmoscopic pigmentary changes . In our patient chloroquine over 15 years caused a photoreceptor cell degeneration outside the area of perifoveal ophthalmoscopic pigmentary changes. The cone and rod degeneration is visible by AO. Spectralis OCT depicted that although photoreceptor cells were diminished in number in degeneration, the cells of inner nuclear layer and ganglion cells were maintained in number. The retinal pigment epithelial cells did not show remarkable changes. We used an adaptive optics retinal camera prototype (rtx1, Imagine Eyes) to evaluate the cone mosaic (1). The apparatus include a wavefront sensor (HASO 32-eye, Imagine Eyes), and a low-noise, high-resolution, charge-coupled device camera (Rope Scientific). The adaptive optics system uses a low-coherence superluminescent diode centered at 750 nm to measure and correct optical distortions and simultaneously control the focus at the retinal layers. The second source (a light-emitting diode with wavelength centered at 850 nm) provides uniform illumination of the retinal field to be imaged (4 degree × 4 degree field). Chui et al. (2) reported that cone photoreceptor packing density decreased from 27.000 cells/mm2 to 7000 cells/mm2 from a retinal eccentricity of 0.30 to 3.40 mm along the superior meridian. Chloroquine is considered to damage directly photoreceptor cells most severely. Matsumura et al. (3) showed by electron microscopy that the first change of experimental chloroquine retinopathy was the appearance of membraneous cytoplasmic body (MCB) in the cytoplasm of ganglion, amacrine, bipolar and horizontal cells. MCB might be degenerated lysosome. Secondarily, these MCB appeared in the inner segments of photoreceptor cells. The outer segments of rod cells disappeared, and then those of cone cells. Although photoreceptor cells were diminished in number in advanced degeneration, the cells of inner nuclear layer and ganglion cells were maintained in number. The retinal pigment epithelial cells did not show other remarkable changes. Bredehorn et al. (4) found that the amphiphilic drug chloroquine caused severe lipidosis in the neuroretina and photoreceptor cell degeneration after chloroquine treatment. After withdrawal of chloroquine the lipidosis remitted, but the degeneration of the photoreceptor cell layer continued to progress. Literature: (1) Lombardo M, Serrao S, Ducoli P, Lombardo G. Variations in image optical quality of the eye and the sampling limit of resolution of the cone mosaic with axial length in young adults. J Cataract Refract Surg. 2012 Jul;38(7):1147-55. doi: 10.1016/j.jcrs.2012.02.033. (2) T.Y.P. Chui, H. Song, S. Burns. Individual variations in human cone photoreceptor packing density: variations with refractive error. Invest Ophthalmol Vis Sci, 49 (2008), pp. 4679–4687 (3) Matsumura, M; Ohkuma, M; Tsukahara, I. Experimental chloroquine retinopathy. Ophthalmic Res., 1986 vol. 18(3) pp. 172-9 (4) Bredehorn T, Duncker GI. Chloroquine- and chlorphentermin-induced lipidosis in rat retina. Klin Monbl Augenheilkd, 1999 vol. 214(3) pp. 178-82

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