Insufficient accommodation in patient with keratoconus

The accommodation response in 10 unoperated patients with keratoconus (mean, 28.3 years) and 10 age-matched normal individuals (mean, 25.8 years) was examined. Using infrared high-speed optometer and iriscorder, quasistatic accommodation and concomitant pupillary response were simultaneously measured by controlling a fixation target for accommodation with a microcomputer. The amplitude of the accommodation response was markedly lower in patients with keratoconus (2.8 +/- 1.4 Diopter) than in controls (4.7 +/- 1.3 Diopter: p less than 0.005). The maximum pupillary responses during far to near accommodation was also significantly decreased in the keratoconus group (0.25 +/- 0.24) when compared with controls (0.56 +/- 0.15; p less than 0.001), despite no statistical difference in pupillary size in the far point between the two groups. The above two pathologic parameters were not found to correlate with the severity of keratoconus. These results suggest that some predisposing abnormalities may exist in the iris and ciliary body of patients with keratoconus, which may be responsible for a paretic pupil that occasionally occurs after corneal transplantation in these patients.