Diabetes mellitus and the eye: axial length

Abstract

Background and aims: The refractive error of the eye is dependent on its axial length. Refractive error is known to fluctuate significantly in poorly controlled diabetic patients. Recently it has been reported that human eyes fluctuate in axial length during the day. However, this change is not detectable in all subjects, suggesting physiological influences such as diet. The purpose of this study was to investigate fluctuations in axial length and blood glucose levels (BGLs) in diabetic patients and control subjects, using partial coherence interferometry. Material and methods: Periodic axial length measurements were taken with an IOLMaster (Zeiss, Oberkochen, Germany) in 21 type 2 diabetic subjects (age 56 ± 11 years), 19 type 1 diabetic subjects (age 38 ± 15 years) and 18 non-diabetic controls (age 46 ± 22 years). Additionally, BGLs were measured using a HemoCue Beta glucose analyser (HemoCue, Ängelholm, Sweden). Measurements were taken between 8AM and 8PM at approximately two hourly intervals. The ocular length variability was mapped against time of day and related to BGLs, age, and the degree of diabetic retinopathy. Results: Axial length variations were found to be significant with time (ANOVA, P=.003) and there was a significant effect for the interaction between group and time of day (ANOVA, P.05) Conclusion: Axial length varies throughout the day in diabetic and control subjects; however, this change does not appear to be significant in every individual. The data suggest a maximum axial length value in the afternoon. Changes in axial length from baseline did not correlate with BGLs, age, or the degree of diabetic retinopathy. Therefore, blood glucose levels may not be the main physiological influence in axial length fluctuations