Abstract
Purpose
To describe the finding of bright hyperautofluorescent streaks in the peripheral retina in tuberous sclerosis.
Observations
A woman with a pathogenic TSC1 mutation and cutaneous manifestations of tuberous sclerosis underwent fundus examination and was found to have a cluster of thin, yellowish streaks in the inferior peripheral fundus of her left eye. The streaks were hyperautofluorescent in blue light and associated with irregular thickening of the photoreceptor-pigment epithelium complex on optical coherence tomography.
Conclusions and importance
The cluster of outer retinal abnormalities in a sector of the peripheral retina in one eye of a TSC1 patient has features in common with the more centrally located and less numerous lesions called achromatic patches. The resemblance of the streak pattern with the pattern of hypoautofluorescence in X-linked retinopathies suggests that the streaks may represent a clone of cells derived from a single somatic mutation in TSC1. The identification of this lesion type expands the scope of conditions that can be diagnosed by fundus imaging.
Benign stationary hamartomas of the retina are found in half of patients with tuberous sclerosis, a systemic disorder that can produce hamartomas in multiple organs, including the central nervous system, skin, kidney, and eye. Familial cases are autosomal dominant. Prominent and common manifestations include epilepsy, learning difficulties, behavioral problems, and autism. Suspicion of the disease is often evoked by skin lesions, which include adenoma sebaceum ( Fig. 1 ), melanotic macules and patches of nevi. The clinical manifestations are highly variable in type and severity. As in retinoblastoma, one autosomal tumor suppressor gene is mutated from birth and clinical manifestations require a somatic mutation to occur in the other allele.
Tuberous sclerosis can be associated with a variety of ocular anomalies, of which retinal astrocytic hamartomas are ophthalmoscopically most conspicuous. The hamartomas are mostly asymptomatic and harmless, but they make an important contribution to the clinical diagnosis. ,
Three types of retinal astrocytic hamartomas are described : Type 1 hamartomas are semitransparent, flat, grayish lesions confined to the retinal nerve fiber layer (RNFL) without signs of calcification, type 2 hamartomas are multinodular, calcified lesions of a mulberry-like appearance, and type 3 contains features of both type 1 and type 2 hamartomas. Type 1 hamartomas may be detectable only by OCT. Type 1 lesions are not autofluorescent, whereas types 2 and type 3 lesions show dotted hyperfluorescence and a heterogeneous internal structure on optical coherence tomography. Additionally, patients with tuberous sclerosis can have achromatic patches in the outer retina. They are sharply delineated retinal pigment epithelial defects, ranging in size from 200 μm pin-point lesions to nearly optic disc-size.
1
Case 1
We have observed unusual fundus features in a 53-year old asymptomatic woman who was examined during the course a family work-up. She was found to have a heterozygous c.164dup, p. (Pro56Alafs*14) mutation in TSC1 and mild facial angiofibromatosis ( Fig. 1 ). Best-corrected visual acuity was Snellen 1.0 in both eyes and applanation tonometry 14 mmHg in both eyes. Slit-lamp examination of the anterior segment was unremarkable, and funduscopy with a 90 D lens and conventional 50-degree color fundus photography found no abnormality in the posterior poles. Wide-field fundus photography (Optos Monaco, Optos Ltd., Edinburgh, UK), however, showed a cluster of thin, bright hyperautofluorescent linear elements in the inferior midperiphery of the fundus ( Fig. 2 ). Three pin-point achromatic patches in the left eye and one in the right eye, which was otherwise normal, were also found to be hyperautofluorescent ( Fig. 2 ). Optical coherence tomography (OCT) scans through the bright streaks showed focal irregularities of overlapping layers of the photoreceptor outer segment/retinal pigment epithelium complex, interspersed with normal-appearing outer layers on adjacent OCT scan lines ( Fig. 3 and online supplement). Also noted was a thin wedge-shaped retinal nerve fiber layer defect or nerve fiber displacement gap that extended from the rim of the optic disc in the left eye at 5 o’clock ( Fig. 2 ). Tangent screen visual field examination was unremarkable in both eyes and no other indication of the presence of glaucoma was found.
