Schlemm's canal measured by optical coherence tomography and correlation study in a healthy Caucasian child population.

Purpose: To measure the Schlemm's canal (SC) in vivo by Fourier-domain optical coherence tomography (FD-OCT) in a Caucasian paediatric population.

Methods: Participants of this cross-sectional study were 290 healthy children. In the right eye of each child, SC cross-sectional diameter and area measurements were made with the FD-OCT instrument RTVue (Optovue Inc, Fremont, CA, USA) in the nasal and temporal quadrants. These SC variables were then assessed for correlation with the factors age, gender, refractive error, anterior chamber angle and trabecular meshwork (TM) metrics. Finally, the reproducibility of the SC measurements was assessed in 30 of the participants.

Results: Mean participant age was 10.7 ± 3.4 years (range 3-18). SC diameters could be measured in both quadrants in 70.6% and 70.4% of subjects, respectively. Mean SC diameters were similar (p = 0.125) for the temporal and nasal quadrants: 266.7 ± 84.1 μm (range 131-509) and 273.2 ± 77.3 μm (range 124-486), respectively. Mean SC areas were also similar (p = 0.167) for the two quadrants: 9975 ± 3514 μm (range 4000-23 000) versus 9688 ± 3297 μm (range 3000-24 000). No differences were detected in SC measurements according to gender, refractive error or angle and TM measurements (R ≤ 0.116; p ≥ 0.125). The exception was age which was directly correlated with SC size (p ≤ 0.041). The reproducibility of the SC measurements was excellent (intraclass correlation coefficients ≥0.936).

Conclusion: FD-OCT allows the identification of the SC in children. Our data indicate an increase in SC size produced with age.