Keratoconus is a deformity of the cornea leading to a conic, irregular deformity of the cornea, usually in its lower quadrant, and astigmatism. It is due to dysplasia of the cornea and generally develops in early adulthood. It may progress over time or may be stable. LASIK surgery is generally contraindicated.
The condition results in variable refractions through different parts of the cornea, possibly resulting in distorted and fluctuating vision, multiple images, sensitivity to light etc. Sudden hydrops of the cornea may occur. Corneal mapping demonstrates the abnormal cornea.
Keratoconus should be suspected in a young applicant who has progressive astigmatism and or a severe or rapidly falling uncorrected visual acuity, pinhole acuity better than can be achieved with best refractive correction, or the retinoscopy reflex is not as regular as normal.
Clinically it may be difficult to see the fundus, and there may be an irregular reflexion of the cornea. Fleisher rings and a Munson’s sign may be seen.
Treatment may include hard contact lenses, cross linking laser UVA surgery to stop progression of the condition and / or insertion of a 'keraring' to normalise the corneal shape.
Applicants with keratoconus should be advised that the condition may deteriorate over time, possibly affecting their eligibility to a medical certificate at some time in the future.