Cataract surgery with autosomal recessive cornea plana caused by a novel KERA mutation

To report a novel mutation in an autosomal recessive corneal plana with visually significant cataracts and a shallow anterior chamber.

Clinical ophthalmic examinations (including corneal topography and biometry) and direct sequencing of the KERA gene were performed.

Genetic testing of a 92-year-old Caucasian gentleman with corneal plana revealed that the patient was homozygous for a KERA missense variant c.659T > C p.(Leu220Ser). This amino acid change occurs within a highly-conserved leucine-rich repeat in keratocan. The threedimensional structure of the keratocan protein was modelled, and the mutated position was found to be within the region of the leucine-rich repeat motifs, destabilizing the structure and leading to the classical ocular phenotype in the affected individual.Scleralization of the cornea, flat keratometry, high astigmatism, and shallow anterior chamber depth make it challenging both for intraocular lens power calculation and cataract surgery. Phacoemulsification was successfully performed along with in-the-bag implantation of a 34D toric intraocular lens in one eye and a 34D plano lens in the other, resulting in a satisfactory refractive outcome.

Using protein modelling, a novel KERA mutation initially classified as variant of uncertain significance, could be identified as potentially pathogeneic. Biometry and cataract surgery in patients with corneal plana are challenging; however, a toric intraocular lens improves visual acuity.