ARCH SOC ESP OFTALMOL 2006; 81: 297-300
SHORT COMMUNICATION
OPTICAL COHERENCE TOMOGRAPHY IN SOLAR ECLIPSE RETINOPATHY TOMOGRAFÍA DE COHERENCIA ÓPTICA EN LA RETINOPATÍA POR ECLIPSE CALVO-GONZÁLEZ C1, RECHE-FRUTOS J1, SANTOS-BUESO E2, DÍAZ-VALLE D2, BENÍTEZ-DEL-CASTILLO JM2, GARCÍA-SÁNCHEZ J2
ABSTRACT
RESUMEN
Case report: We describe the case of a patient suffering from acute visual loss soon after watching a solar eclipse. Optical coherence tomography was the main diagnostic tool used. Discussion: Solar retinopathy is now an unusual cause of visual loss, although there are still some cases diagnosed, especially after viewing solar eclipses. Optical coherence tomography is suitable for detecting permanent retinal injuries related to solar exposure, with the outer retinal layers being typically affected(Arch Soc Esp Oftalmol 2006; 81: 297-300).
Caso clínico: Se describe el caso de un paciente que sufrió pérdida visual aguda tras visualización directa y mantenida de un eclipse solar. El diagnóstico se realiza principalmente mediante tomografía de coherencia óptica. Discusión: La retinopatía solar es actualmente una causa poco frecuente de pérdida visual. No obstante, se describen algunos casos, especialmente tras la visualización de eclipses de sol. La tomografía de coherencia óptica constituye una prueba diagnóstica adecuada para detectar alteraciones, de forma característica, en las capas más externas de la retina, secundarias a la exposición solar constante.
Key words: Solar retinopathy, optical coherence tomography.
INTRODUCTION Solar retinopathy has been documented for many years. The cases described at present are related to direct exposure to solar radiations in well-defined circumstances such as solar eclipses, psychiatric disease, religious rituals, use of hallucinogenic
Palabras clave: Retinopatía solar, tomografía coherencia óptica.
drugs, military and astronomy professionals (1). It is believed that the mechanism which causes the damage is photochemical, involving mainly the outermost retinal layers. The most frequent visual symptoms are reduction of visual acuity and central scotoma. Exploration shows a small yellowish foveal lesion (2,3). The diagnostic is usually made with
Received: 2/1/06. Accepted: 28/4/06. Unidad de Superficie e Inflamación Ocular. Servicio de Oftalmología. Hospital Clínico San Carlos. Madrid. España. 1 Graduate in Medicine. 2 Ph.D. in Medicine. Correspondence: C. Calvo González Servicio de Oftalmología. Hospital Clínico San Carlos Avda. Prof. Martín Lagos, s/n 28040 Madrid Spain E-mail:
[email protected]
CALVO-GONZÁLEZ C, et al.
anamnesis and funduscopy. Fluorescein angiography (FA) doesn’t usually show alterations. The recent introduction of Optical Coherence Tomography (OCT) has opened new diagnostic possibilities.
CASE REPORT A male patient, 30 years old, without relevant history, is attended in the urgency admission section due to sudden reduction of vision and central scotoma in the right eye (RE). He referred gazing directly and continuously at the sun through his RE for 3 minutes during the solar eclipse which took place Oct. 3, 2005. In the exploration, the best corrected visual acuity was of 20/50 in the RE and 20/25 (Snellen) in the left eye (LE). The anterior segment was within normal ranges, as were the pupillary reflexes of the retinal pigmentary epithelium (RPE) and a yellowish lesion in the foveal area (fig. 1). Fluorescein angiography values were within normal ranges, as well as the visual field (Octopusestrategia Top). Amsler’s grid did not exhibit alterations. Exploration with OCT-III revealed a clear defect in the external segment of foveal photoreceptors, without any other significant findings (fig. 2). The patient was checked again two months later, repeating the diagnostic tests performed in the first checkup. Best corrected visual acuity had gone down in the RE to 20/80, remaining stable in the LE. In addition, the patient referred dischromatop-
Fig. 1: Funduscopic image of RE, showing yellowish dotted lesion in foveal area.
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Fig. 2: RE OCT clearly showing a defect in the hyperreflecting external layer of foveal photoreceptors.
sia. The Farnsworth 25 chromatic test did not show alterations. The OCT revealed a defect in the external segment of foveal photoreceptors although of a lesser magnitude than the one of the first assessment (the defect was compared with the same OCT section) (fig. 3). The remaining tests performed yielded normal results.
DISCUSSION Solar retinopathy is characterized by the involvement of the outermost layers of the retina. Three mechanisms have been described which could explain said retinal damage. The retina pigmentary epithelium (RPE) absorbs an important percentage of solar radiations with an ensuing increase of tissue temperature in surrounding areas, thus producing thermal damage. On the other hand the high energy waves and low levels of ultra-violet (UV) A
Fig. 3: OCT of the same eye two months later, showing a smaller defect in the external segment of photoreceptors.
ARCH SOC ESP OFTALMOL 2006; 81: 297-300
Solar retinopathy
or radiations close to UV (320-400 nm) are responsible for the photochemical damage. It is generally believed that retinal involvement could be the result of the combination of thermal and photochemical damage (4). Solar radiation produce pointed damage in the apical melanosomes of the RPE followed by alterations in the outermost segment of foveal photoreceptors (1,5). The defect depends directly on the intensity, duration, exposure range, pupillar dilatation, the transparency of the means, the focusing and refraction capacity, with higher risk for slight emmetrope or hypermetrope in whom radiations are transmitted directly to the fovea (4). Funduscopic exploration typically shows a characteristic yellowish lesion in the foveal area. Frequently, FA is normal although it sometimes shows diffusion of contrast in the acute phase as well as window defects in the chronic (2). The alterations described by OCTIII show excavation areas in the hyperreflecting layers of the RPE and of the outermost segments of the photoreceptor layer (1,2,4). Some authors have described via OCT the presence of a hyper-reflecting point in the vitreous cavity at about 70 µm from the retina (4). The most frequent symp-
toms are reduction of VA, metamorphopsies, central scotoma, dischromatopsia and photophobia. In conclusion, the main diagnostic of this entity is mainly based on anamnesis and funduscopic observation due to the lack of data provided by FA. The diffusion of the OCT would facilitate solar retinopathy diagnosis.
REFERENCES 1. Kaushik S, Gupta V, Gupta A. Optical coherence tomography findings in solar retinopathy. Ophthalmic Surg Lasers Imaging 2004; 35: 52-55. 2. Jorge R, Costa RA, Quirino LS, Paques MW, Calucci D, Cardillo JA, et al. Optical coherence tomography findings in patients with late solar retinopathy. Am J Ophthalmol 2004; 137: 1139-1143. 3. Yannuzzi LA, Fisher YL, Slakter JS, Krueger A. Solar retinipathy. A photobiologic and geophisical analysis. Retina 1989; 9: 28-43. 4. Codenotti M, Patelli F, Brancato R. OCT findings in patients with retinopathy after watching a solar eclipse. Ophthalmologica 2002; 216: 463-466. 5. Garg SJ, Martidis A, Nelson ML, Sivalingam A. Optical coherence tomography of chronic solar retinopathy. Am J Ophthalmol 2004; 137: 351-354.
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