This page reveals the answer
Want to test yourself first? Play the original case before reading the clues and explanation below.
Five progressive clues
These are the case findings in their original reveal order, moving from the broader presentation to the most discriminating evidence.
Clue 1
A 19-year-old engineering student has had his glasses remade three times in eighteen months and still complains that streetlights smear into overlapping ghost images at night. He mentions he rubs his eyes hard every morning because of allergies.
Clue 2
Each new prescription carries more cylinder than the last and the axis has rotated substantially between visits. Best-corrected acuity in the right eye has slipped from 20/20 to 20/50 despite an accurate refraction, and he sees several overlapping images even with one eye covered.
Clue 3
Retinoscopy shows a scissoring reflex in both eyes, and the red reflex on direct ophthalmoscopy has a central oil-droplet appearance. He also has atopic dermatitis and a history of vernal conjunctivitis.
Clue 4
Corneal topography shows inferior steepening with an asymmetric bowtie pattern, maximum keratometry of 54.8 D in the right eye, and central pachymetry of 452 microns with the thinnest point displaced inferotemporally.
Clue 5
On slit-lamp exam fine vertical stress lines are visible in the deep stroma, and asking the patient to look down produces a V-shaped indentation of the lower lid margin by the protruding cornea.
Diagnosis
Keratoconus
Why the diagnosis fits
Progressive non-inflammatory thinning and forward protrusion of the central-to-inferior cornea produces irregular astigmatism that spectacles cannot fully correct and that worsens over time. The key discriminator from ordinary high astigmatism is the mismatch between an accurate refraction and best-corrected acuity, together with asymmetric inferior steepening and thinning on topography. Eye rubbing and atopy are strongly associated, and corneal cross-linking halts progression when started early.
Educational reference
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Open the clinical referenceFor education and entertainment only. This fictional case is not medical advice and does not replace supervised clinical training, diagnosis, or treatment.