Schnyder's dystrophy. Progression and metabolism.

In the first long-term cohort study of Schnyder's corneal dystrophy the authors examined affected and unaffected members of two unrelated families in 1975 and 1976 respectively, and again in 1984. They identified carriers, catalogued changes in the diffuse and crystalline corneal opacities which characterize this dystrophy and analysed the patient's lipid metabolism. Corneal opacities never regressed. Progression was more frequent in diffuse than in crystalline opacities. Both crystalline and diffuse opacities reappeared and progressed following penetrating keratoplasty. Mean cholesterol levels in the carrier group were above normal and six had a moderate type IIa dyslipoproteinemia; conversely, two carriers had low apo B. The degree of corneal opacification showed no relationship to dyslipoproteinemia. Schnyder's corneal dystrophy appears to involve the corneal lipid metabolism only and not to be a systemic disease.