Woman experiences gradual visual loss over 6 months

Subtle retinal pigment epithelium changes were seen on fundus examination.

Mark E. Patron

Andre J. Witkin

A 47-year-old woman was referred to the New England Eye Center at Tufts Medical Center for evaluation of bilateral decreased visual acuity for the past 6 months. She noted difficulty in reading at near with glasses and in discerning signs while driving. She was not aware of any variation in symptoms with either bright or dim ambient light. She felt the onset of visual loss had initially been gradual but was now nonprogressive.

The patient has suffered from narcotic and benzodiazepine addiction for the last several years, and although in recovery for 4 months, she was concerned it may have contributed to her visual difficulties.

The patient denied any ocular problems in the past and was largely healthy except for her medication dependence and an underlying diagnosis of depression. Her medications included escitalopram, clonazepam, topiramate, lamotrigine and quetiapine. She was unemployed with RN training and denied tobacco or significant alcohol use.

Examination

Best corrected visual acuity was 20/30 in the right eye and 20/25 in the left eye. Color vision, motility and alignment were all normal. Amsler grid and 30-2 Humphrey visual field examinations were performed, both without defect. Her pupils were round and reactive with no relative afferent pupillary defect. IOPs were normal in both eyes.

Figures 1a and 1b. Fluorescein angiography showing small transmission defects at the foveolae of both eyes. Images: Lazzara MD and Hedges TR

Figures 2a and 2b. Spectral-domain optical coherence tomography demonstrating disruptions in the inner segment/outer segment junction and photoreceptor outer segments.

Anterior segment examination was unremarkable in both eyes. The vitreous was quiet in both eyes. Fundus examination was largely normal except for very subtle retinal pigment epithelium (RPE) changes centrally in both maculae. Fluorescein angiography (Figures 1a and 1b) and spectral-domain optical coherence tomography (Figures 2a and 2b) images were obtained.

What is your diagnosis?

Subtle RPE changes in maculae

Fluorescein angiography showed small transmission defects at the foveolae of both eyes corresponding to the areas of subtle RPE changes seen on biomicroscopy. Spectral-domain OCT was performed. Small, discrete areas of hyporeflective disruptions in the inner segment/outer segment, or IS/OS, junction and photoreceptor outer segments were seen bilaterally and relatively symmetrically.

This constellation of findings, especially on OCT, is rather unique. Before additional questioning, the diagnosis was felt likely to be solar retinopathy, although additional etiologies such as drug-related maculopathy, idiopathic macular telangiectasia type 2 and early bilateral macular holes were included in the differential. While OCT images continued to further elucidate the above-mentioned diseases, from our experience, the OCT findings seen in this patient have only been seen in solar retinopathy. On further questioning, the patient admitted to sun-gazing, offering that she could “stare at the sun for hours.” A diagnosis of solar retinopathy was made.

Discussion

Light is able to affect the retina in three ways: mechanical, thermal and photochemical. Thermal and photochemical means are involved in solar retinopathy. Thermal damage occurs via photocoagulation and requires a 10°C to 20°C temperature elevation to cause protein denaturation and enzyme inactivation. This threshold is thought to be only surmountable with mydriatic pupils and extended solar viewing. More commonly, excessive photon absorption by tissues causes molecular changes and ultimately cellular damage.

In solar retinopathy, patients usually complain of decreased acuity, central scotomata, metamorphopsia and dyschromatopsia. Findings on examination vary based on chronicity and are typically subtle. Initially, a yellow-white spot is seen in the fovea with or without a surrounding granular gray halo. This spot evolves into a reddish, sharply demarcated cyst-like lesion.

Only about 50% of patients ultimately diagnosed with solar retinopathy admit to or recall looking at the sun. Associations include solar-eclipse viewing, religious-associated sun-gazing or worshiping, and possibly work with a welding arc. In addition, a higher incidence of solar retinal damage has been seen in patients with psychiatric illnesses such as schizophrenia; whether this is related to behavioral changes inherent in the underlying condition or treatment is unknown. Mydriatic effects of psychotropic medications themselves may play a role.

Abnormalities are typically seen on fluorescein angiography, OCT and multifocal electroretinography. Solar damage to the RPE creates window defects seen as pinpoint areas of hyperfluorescence without leakage on fluorescein angiography. OCT findings are most helpful and include hyporeflective disruptions in the photoreceptor IS/OS junction and photoreceptor outer segments. The findings seen in patients who have undergone multifocal electroretinograms reveal wider (foveal and perifoveal) than anticipated central depressions given the focal OCT damage. Finally, fundus autofluorescence has demonstrated hypoautofluorescence of these central lesions surrounded by a halo of relatively increased signal.

Initial visual acuity can vary considerably from 20/20 to 20/400. Most patients will find an improvement in vision within 6 months, generally to 20/40 or better. A study done by Gulkilik et al evaluating the effects of a solar eclipse in Turkey in 1999 showed a strong correlation between full-thickness retinal lesions of the outer nuclear layer on OCT and permanent visual acuity loss. Small case series have evaluated the treatment of acute lesions with steroids, but no definitive conclusions have been made, largely because of the natural tendency toward improvement. Treatment is typically directed toward prevention of further incidents and includes education and use of protective eyewear.

References:

• Baumal CR. Light toxicity and laser burns. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis: Mosby/Elsevier; 2008.
• Chen RW, Gorczynska I, Srinivasan VJ, Fujimoto JG, Duker JS, Reichel E. High-speed ultrahigh-resolution optical coherence tomography findings in chronic solar retinopathy. Retin Cases Brief Rep. 2008;2(2):103-105.
• dell’Omo R, Konstantopoulou K, Wong R, Pavesio C. Presumed idiopathic outer lamellar defects of the fovea and chronic solar retinopathy: an OCT and fundus autofluorescence study. Br J Ophthalmol. 2009;93(11):1483-1487.
• Gulkilik G, Taskapili M, Kocabora S, Demirci G, Muftuoglu GI. Association between visual acuity loss and optical coherence tomography findings in patients with late solar retinopathy. Retina. 2009;29(2):257-261.
• Jain A, Desai RU, Charalel RA, Quiram P, Yannuzzi L, Sarraf D. Solar retinopathy: comparison of optical coherence tomography (OCT) and fluorescein angiography (FA). Retina. 2009;29(9):1340-1345.
• Michaelides M, Rajendram R, Marshall J, Keightley S. Eclipse retinopathy. Eye (Lond). 2001;15(Pt 2):148-151.
• Stangos AN, Petropoulos IK, Pournaras JA, Zaninetti M, Borruat FX, Pournaras CJ. Optical coherence tomography and multifocal electro-retinogram findings in chronic solar retinopathy. Am J Ophthalmol. 2007;144(1):131-134.

• Matthew D. Lazzara, MD, and Thomas R. Hedges III, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; website: www.neec.com.

• Edited by Mark E. Patron, MD, and Andre J. Witkin, MD. Drs. Patron and Witkin can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; website: www.neec.com.