Abstract
PURPOSE: To explore the potential effect of ageing on the corneal curvature and corrected visual acuity in patients with long-term keratoconus because of the paucity of these patients older than 50 years. METHODS: Records of keratoconic patients, who had initially presented to a specialized contact lens clinic and followed for more than 20 years after disease onset, were reviewed. Collected information included age, gender, date of first and last examination, date of onset of the disease, central corneal curvature, refraction, best corrected visual acuity (BCVA), therapeutic modality and clinical signs. RESULTS: Age of patients at last examination was 53.8 years±7.2 (range 44-67 years). Disease onset was self-reported to be at age 18.4 years±3.8. First examination was at age 25.1 years±9.4 and the mean number of years between first and last examination was 28.7 years. Mean central corneal curvature was 6.87mm (48.77D)±0.65 and 6.56mm (51.09D)±0.74, at first and last examination, respectively, a difference which was significant (p<0.001). However, the last measurement of corneal curvature was found to remain approximately constant over the years from about 20 to 50 years after onset. Mean BCVA was not significantly different between first and last examination and was found to be approximately constant over the years. CONCLUSION: Corneal curvature became steeper possibly within the first 20 years after disease onset but remained approximately unchanged afterwards. Likewise, BCVA remained practically constant over the years indicating relative stability of the disease after 20 years.