Abstract
Purpose: :
To investigate the interindividual "in vivo" anatomical variability of the ciliary processes using ultrasound biomicroscopy (UBM) and to analyse the influence of age, sex, ocular structural factors and refractive error on ciliary biometry in a large group of healthy subjects.
Methods: :
80 eyes from 40 healthy Caucasian subjects were enrolled in a cross-sectional study. The sample was stratified by age in four groups (A=from 20 to 29 years; B=from 30 to 39 years; C=from 40 to 49 years; D=from 50 to 59 years) of 10 subjects (5 men and 5 women) for statistical analysis purpose. Comprehensive ophthalmic examination including best corrected distance/near visual acuity and spherical equivalent (SE) assessment was performed. Axial length (AL), corneal curvature (CC) and anterior chamber depth (ACD) were obtained by optical biometry system (IOL Master, Carl Zeiss AG, Feldbach, Switzerland). Each eye underwent UBM (Zeiss-Humphrey Inc., San Leandro, CA, USA) using a 50 MHz transducer and received 1 temporal radial section and 4 transverse sections behind the limbus on temporal, inferior, nasal and superior sectors of the eye, respectively. The following parameters were examined: scleral ciliary process angle (SCPA); position of the ciliary process with respect to the scleral spur (before/behind) measured on a line extending from the scleral spur perpendicularly through the iris to the ciliary process; number of the ciliary processes within each section (N); height of the ciliary processes within each section (H); morphology (regular/irregular).
Results: :
60% of the subjects were emmetropic, 16.4% were myopic, 23.6% were hyperopic. The ciliary processes were found to be placed before the scleral spur in 93.3% of the eyes. The analysis showed a negative correlation between SE and SCPA (r=-0.3; p=0.01) and between SE and H in the inferior (r=-0.29; p=0.01) and superior (r=-0.43; p<0.001) sectors. A positive correlation between AL and H in the inferior (r=0.355; p=0.002), nasal (r=0.305; p=0.009), superior (r=0.51; p<0.001) sectors was found. The analysis showed a negative correlation between AL and N in the nasal (r=-0.248; p=0.03) and superior (r=-0.263; p=0.29) sectors. SCPA was found to be lower in group C (38.4°) than in groups A (44.6°), B (44.5°), D (43.8°) (p<0.05).
Conclusions: :
Ciliary processes seems to be longer, less numerous and back-rotated in myopic eyes, while SCPA decreases in subjects whose age ranged from 40 to 49 years. The analysis failed to show any relationship between the N and H of the ciliary processes and age/sex.
Keywords: ciliary processes • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • ciliary body