Analysis of Axial Length in Young Patients with Marfan Syndrome and Bilateral Ectopia Lentis by Z-Scores

Abstract

Introduction: Marfan syndrome (MFS) is characterized by ectopia lentis (EL) and elongated axial length (AL). The characteristics of AL in young patients with MFS and bilateral EL before the lens surgery are not fully understood.

Methods: This study reviewed MFS patients under 20 years old with bilateral EL from January 2015 to October 2020. The Z-scores were introduced in terms of the number of standard deviations from the mean of age-matched normative data. Using Z-scores, the distribution of AL and influence factors were evaluated. The correlations between AL and other biometrics were analyzed.

Results: We reviewed 183 patients and enrolled both eyes. The mean age was 8.44 ± 4.69 years. About 36% of the patients were children under 6 years old. The median AL increased from 23.16 mm under 5 years old to 26.20 mm in the 16-20 age group, and when plotted, the trend presented a logarithmic curvature (R2 = 0.145, p < 0.001). The median Z-AL score was 1.24. One-third of eyes had Z-score <0. About 20% of the patients had AL difference over 1 mm between the right and left eyes, and the right one had longer Z-AL scores (p = 0.013). The eye complicated with megalocornea (10, 7.04%) had larger Z-AL scores (4.72 ± 3.51 vs. 1.10 ± 2.25, p = 0.002). A positive correlation was found between Z-AL and Z-corneal curvature radius (r = 0.265, p < 0.001).

Conclusion: Young patients with bilateral EL but small AL should not be excluded from MFS without systematic examination. The age-adjusted Z-score will facilitate further study of the individual variations in AL across different ages.

Keywords: Axial length; Ectopia lentis; Marfan syndrome; Z-score.