Long-term longitudinal changes in axial length in the Caucasian myopic and hyperopic population with a phakic intraocular lens

Abstract

Purpose: To determine the long-term longitudinal axial length changes in myopic and hyperopic adults with an iris-fixated phakic intraocular lens (pIOL).

Methods: The medical records of patients aged ≥18 years with myopia or hyperopia who were treated with pIOL implantation between 1996 and 2011 for refractive correction with a minimum follow-up of 5 years after pIOL implantation were analyzed. The main outcome measure was change in ocular axial length over time.

Results: 149 eyes of 149 myopic patients and 27 hyperopic eyes of 27 patients were included in this study. Mean patient age was 37.1 ± 10.4 years (35% male) in the myopic group and 39.4 ± 9.4 years (4% male) in the hyperopic group. The eyes of the myopic patients showed a significant mean increase in axial length of 0.45 ± 0.61 mm after a mean follow-up time of 144 ± 38 months (p < 0.001). In 26 eyes (17%), the axial length had increased by ≥1 mm. The mean annual axial length increase was 0.04 ± 0.06 mm. Axial elongation was associated with a higher degree of myopia (p < 0.001) and younger age (p = 0.02). The eyes of the hyperopic patients showed no change in axial length over time.

Conclusions: Myopic eyes corrected with an iris-fixated pIOL show continuous increase in axial length at an adult age. Although this study is limited to subjects with a pIOL, this is the first time myopization in Caucasian adults has been reported in a large long-term longitudinal study.

Keywords: axial elongation; axial length; hyperopia; myopia; phakic intraocular lens; refractive error.

Fig. 1

Scatter plot showing differences in axial length (AL) changes over time in (A) myopic eyes and (B) hyperopic eyes with a pIOL in millimetres (mm). A positive difference responds to an increase in AL between the first and last measurements. Black line: mean. Black dashed lines: 95% confidence interval of the limits of agreement.

Fig. 2

Box plot showing axial length (AL) change per year in millimetres (mm) associated with axial length at baseline with respect to age at baseline. blue: 18–30 years, red: 31–45 years, grey: 46–60 years.