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Updated: Feb 7, 2026

Three Different Protocols of Corneal Collagen Crosslinking in Keratoconus: Conventional, Accelerated and Iontophoresis
Published on: November 12, 2015
Classic homocystinuria and keratoconus: a case report
Patrícia Ioschpe Gus1, Natália Paseto Pilati2, Bruna Ossanai Schoenardie2
1Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil.
Abstract:
Homocystinuria is one of a group of genetic disorders called inborn errors of metabolism. It is characterized by a deficiency of the enzyme that converts homocysteine to cystathionine. Keratoconus is an ophthalmologic condition characterized by thinning of the corneal stroma, which causes the cornea to assume a conical shape. There is little information in the scientific literature about the association between keratoconus and homocystinuria. We believe that a collagen cross-linking defect may be the key to understand the connection between these two conditions. This case report describes a 38-year-old male patient with a diagnosis of classical homocystinuria since age 13. At the age of 16, he received a diagnosis of asymmetrical keratoconus when referred for lensectomy with vitrectomy of his left eye. To the best of our knowledge, this is the first report of a patient with simultaneous homocystinuria and keratoconus.
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