Scanning slit topography: Diagnostic boon in presumed unilateral Terrien's marginal degeneration

PurposeTo describe the scanning slit topography in two children with presumed unilateral Terrien's marginal degeneration.MethodsTwo girls aged 9 and 12 years presented with redness and reduced vision in their right eyes. The younger patient had scarring adjacent to the superior limbus, with vessels coursing across, and lipid deposition. Visual acuity improved to 20/20 from 20/400 with +1.0 −3.5 × 90°. The older patient had similar features inferiorly. Her visual acuity improved to 20/20 from 20/40 with −3.5 × 65°. Their left eyes were normal. A diagnosis of unilateral Terrien's Marginal Degeneration (TMD) was made.ResultsScanning slit topography (Orbscan II™, Orbscan Inc., Salt Lake City, UT) of the right eyes revealed high against-the-rule astigmatism. The left eyes showed elevations of anterior and posterior corneal surface above the best-fit-sphere, skewing of principal meridians and increased astigmatism from 3.0 to 5.0 mm zones. Based on these findings bilateral asymmetric TMD was diagnosed.ConclusionThough the diagnosis of TMD is mainly clinical, scanning slit topography findings in TMD have not been described earlier and are useful in establishing the diagnosis of bilateral asymmetric TMD.

► 2 children were diagnosed with unilateral Terriens marginal degeneration based on slit lamp biomicroscopy.
► Scanning slit topography was done.
► Topographic findings confirmed diagnosis in the affected eye.
► Subtle abnormalities picked up in apparently normal eye led to revision of diagnosis to bilateral Terrien's marginal degeneration.
► Topography proved to be invaluable in making this diagnosis.