Optical coherence tomography findings and successful repair of retina detachment in Knobloch syndrome

Abstract

A 7-year-old Afghani girl was referred to the retina clinic of Massachusetts Eye and Ear for a chronic-appearing, macula-off retinal detachment in the left eye. On examination, best-corrected visual acuity was 20/400 in the right eye and 20/800 in the left eye. She had bilateral horizontal nystagmus. Ophthalmoscopy revealed prominent choroidal vessels, chorioretinal atrophy in the macular area, attenuated retinal vasculature, and pale optic discs bilaterally. Spectral domain optical coherence tomography demonstrated atrophy of the choriocapillaris and the retinal pigment epithelium, retinal thinning, and abnormal foveal contour. In the right eye, findings were reminiscent of dome shape maculopathy with an adjacent lesion suspicious for inactive choroidal neovascularization. A suspected diagnosis of Knobloch syndrome was confirmed by genetic testing, which showed a homozygous variant in exon 33 of the COL18A1 gene defined as c.3213dupC. She underwent cryotherapy and scleral buckling surgery in the left eye and remained attached bilaterally at 3 years' follow-up, with progressive myopia and best-corrected visual acuity of 20/100 in the right eye and 20/125 in the left eye.

Figure 1

Widefield fundus photograph, B scan, and spectral domain optical coherence tomography (SD-OCT) at initial presentation. A, Fundus photograph of the right eye showing areas of optically empty vitreous, slightly tilted pale optic disc, posterior staphyloma, attenuated arteries, widespread pigmentary changes, and a focal choroioretinal atrophy (black arrowhead) at the inferotemporal part of the macula. B, Fundus photograph of the left eye showing areas of optically empty vitreous, slightly pale optic disc, a patch of chorioretinal atrophy at the temporal macula (black arrowhead), posterior staphyloma, attenuated arteries, and an inferior retinal detachment, with no a tear inferotemporally. C, B-scan ultrasonography of the left eye demonstrating a membrane consistent with retinal detachment. D, SD-OCT scans through the fovea of the right eye revealing prominent choroidal vessels (white arrow) and atrophic retina, retinal pigment epithelium, and choriocapillaris. There is a homogenous hyper reflectivity in the internal retinal layers (white star) and a lack of the normal foveal contour. The outline of the sclera is partially visible (white arrowhead). E, SD-OCT through the fovea of the left eye shows subretinal fluid beneath the fovea (white arrowhead).

Figure 2

Spectral domain optical coherence tomography image of the right macula next to depigmented chorioretinal and retinal pigment epithelial atrophy. There is an elevated subretinal lesion without intra- or subretinal fluid, thus suspicious for inactive choroidal neovascularization (white arrow). The adjacent retina shows schisis (white arrowheads). The right side of the image shows a staphyloma (the area under the angled line with two arrowheads). The choroid is atrophic in this section and is only visible in the left part of the image (white star). The scleral outline (line with two arrowheads) can be seen very clearly, and there is an area reminiscent of dome-shaped maculopathy.