Change in major ocular biometry parameters axial length and keratometry in adults over time

To determine how much axial length (AL) and average keratometry (K) change over time in elderly patients and to assess clinical necessity of repeating biometry in instances where the second eye is operated on 6 months or more after the first.

Northwestern Memorial Hospital, Chicago, Illinois.

Retrospective study.

Inclusion criteria were patients older than 35 years, with 2 biometry measurements over 6 months apart, measured with the IOL Master 700 from January 1, 2016, to September 15, 2020. Patients were excluded if they had any other intraocular surgery besides cataract. A linear mixed model and SPSS software was used to compare measurements among timepoints.

201 patients (402 eyes) were included (average age 73.3, 59.3% female). Average time between biometry measurements was 21.5 months (range 6 to 48 months). The mean change in AL was 0.04 mm (95% CI, 0.03 to 0.05, P = .10). The mean change in K was 0.01 diopters (95% CI, -0.10 to 0.30, P = .33). At the 6-month to 1-year interval (n = 73), mean change in AL was 0.04 mm. Mean change in AL did not significantly increase with greater time intervals. There was no correlation between time and ΔAL ( P = .70), nor between time and ΔK ( P = .98).

In this cohort, biometric parameters did not change significantly over time. Repeating biometry at a 1- to 2-year interval for elderly patients receiving monofocal implants may offer limited benefit.