Interocular axial length difference and age-related cataract.

PURPOSE

To evaluate interocular differences in axial length and its relation to increasing axial length and postoperative refractive predictability in patients with age-related cataract.

SETTING

Moorfields Eye Hospital, London, United Kingdom.

METHODS

Preoperative biometry and postoperative refractive outcomes were analyzed in a consecutive series of 1537 patients who had uneventful bilateral phacoemulsification. In 1379 patients with bilateral data, the difference in axial lengths between eyes and the magnitude of postoperative anisometropia were compared between 1.0 mm incremental groups of axial length using the longer eye as the index eye. The postoperative refraction prediction error in 1457 left eyes was assessed in similar axial length groups.

RESULTS

The difference in axial length was 0.3 mm or greater in 331 patients (24%). Axial length asymmetry between eyes increased with an increase in axial length in the index eye (P<.001). The 95th centile of the axial length difference was 0.5 mm when the longer eye was 22.0 mm or less and 4.0 mm when it was 28 mm or greater. There was also an increase in postoperative anisometropia with increasing axial length (P = .003). The median was 0.34 D (interquartile range [IR], 0.25-1.11) when the longer eye had an axial length of less than 28.0 mm and 0.66 D (IR, 0.16-0.66) when the longer eye had an axial length of 28.0 mm or more. In left eyes, there was an increase in biometry prediction error with an increase in axial length (P = .006).

CONCLUSION

An increase in axial length was associated with greater asymmetry between eyes and more postoperative anisometropia, especially in eyes with an axial length greater than 28.0 mm.