Keratoconus

Considerations

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.

Information to be provided

• On the first occasion that an applicant presents with keratoconus or suspected keratoconus, a special eye report by an accredited optometrist must be provided;
• Copy of all reports by any ophthalmologist consulted, to include any corneal mapping report and images;
• An annual special eye report should be provided;
• If the condition remains mild and has proven itself to be stable over several years, a reduced surveillance may later be considered.

Disposition in the case of keratoconus

• An applicant with keratoconus who first apply for a Class 1, 2 or 3 medical certificate should be considered as having a condition that is of aeromedical significance;
• An applicant with known keratoconus who re-applies for a medical certificate 1, 2 or 3, and who has an uncorrected vision of 6/24 or better in each eye, has corrected vision of 6/9 or better in each eye and has demonstrated stability over five years or more; may be assessed as having a condition that is not of aeromedical significance.

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.