BACKGROUND: Terrien’s marginal degeneration (TMD) is a rare, non-inflammatory condition characterized by progressive bilateral, often asymmetric thinning of the peripheral corneal stroma. It most commonly affects males 40 years or older. It typically presents superonasally as fine yellow-white, punctate stromal opacities followed by mild superficial corneal vascularization. As the disease progresses, the corneal stroma thins circumferentially resulting in increased irregular astigmatism. Mild cases are correctable with conventional spectacles or contact lenses. As the corneal irregularity increases, rigid gas permeable (RGP) lenses are often needed to provide significant visual improvement. When RGP lenses become difficult to fit or the risk of perforation increases, the treatment of choice is corneal surgery. Another consideration for an unsuccessful corneal RGP fit is a scleral contact lens. Scleral lenses correct refractive surface abnormalities while protecting the cornea from minor trauma. This presentation describes the bilateral scleral lens fitting of a TMD patient which resulted in good visual acuity OD, but did not provide the improvement in visual acuity OS that was expected.
CASE REPORT(S). A 58-year old Caucasian male with a history of TMD was referred for scleral lens fitting. Symmetrical reduction in visual acuities OU began 30 years prior, with a significant decrease in the OS two years ago. Entering spectacle acuities were 20/50-2 OD and CF OS. Slit lamp exam revealed circumferential peripheral thinning OU with areas of opacification superiorly OD and nasally OS. A scleral lens provided best-corrected visual acuities of 20/40+3 OD and 20/400 OS, PH-NI. Pupillary testing revealed a mild afferent pupillary defect OS. Examination of the optic nerve heads revealed disc pallor OS compared to OD. This patient was referred to a neuro-ophthalmologist for further evaluation as to the etiology of the disc pallor and reduced vision OS.
CONCLUSIONS. For patients with reduced visual acuity presumably caused by a corneal pathology such as TMD, practitioners should not overlook other sources for the reduced acuity.