A Case of Knobloch Syndrome With Lens Dislocation Resembling Homocystinuria

We report a 39-year-old woman with lifelong visual impairment who presented in June 2024 with progressive visual deterioration in her right eye. Ophthalmologic evaluation revealed severe high myopia, vitreoretinal degeneration, phthisis bulbi of the left eye, and downward lens dislocation of the right eye. Neurological workup revealed bilaterally blurred optic discs, an elevated cerebrospinal fluid opening pressure of 31 cm H₂O that normalized on repeat lumbar puncture, nonspecific white matter signal changes on MRI, and bilateral frontal polymicrogyria. Initial mild homocysteine elevation prompted consideration of homocystinuria; however, whole-exome sequencing identified a homozygous frameshift mutation in COL18A1 (c.2824_2831del, p.Gly942Argfs*142), confirming Knobloch syndrome type 1. This case illustrates an adult presentation of Knobloch syndrome with retinitis pigmentosa-like retinal changes and lens dislocation mimicking homocystinuria.