Ultrasound biomicroscopy correlation with corneal diameter in pediatric patients

Abstract

Purpose : Prior studies have established ultrasound biomicroscopy (UBM) as a clinically valuable imaging modality for structural anterior segment assessment, but its correlation with standard measures of ocular size, such as corneal diameter (CD), has not been examined. CD evaluation is pertinent to cataract surgery planning, and diagnosis and monitoring for congenital conditions such as microcornea, megalocornea, and congenital glaucoma. CD is typically measured using a ruler, calipers, or gray-scale steps devices. These external CD measurements are subject to error and variability, prompting our investigation of measuring corneal dimensions internally from UBM images.

Using a prospective cohort of healthy controls, we tested the hypothesis that CD correlates with internal corneal span determined from the angle-to-angle (AA) distance measured in UBM images.

Methods :
We collected 45 digital external photos and 86 UBM images of a total of 43 eyes from 24 participants between ages 1 – 12 years without ocular disease. We measured horizontal (H) and vertical (V) CD in each external photo using ImageJ software. We also used ImageJ to measure the internal angle-to-angle (AA) distance in H and V cross-sectional UBM images of each eye.

Results : Horizontal and vertical CD and AA measurements were highly positively correlated, as determined by Pearson correlation coefficients of +0.97 and +0.96, respectively. Bland-Altman plots demonstrated high agreement between methods for both H and V measurements (Fig. 1). Regression analysis revealed a linear relationship between CD and AA for H (Fig. 2A, CD = 0.99 x AA + 0.17, R² = 0.94, P<0.0001) and V (Fig. 2B, CD = 0.96 x AA + 0.44, R² = 0.92, P<0.0001) measurements.

Conclusions :
UBM image analysis can be used to accurately quantify corneal diameter in children with healthy corneas, as shown by the strong correlation between CD and AA measurements. Given its high resolution and non-invasive nature, UBM may be a useful alternative for determining CD. Further studies are needed to understand the potential to determine CD from AA distance in patients with ocular diseases that may impact the cornea, such as primary congenital glaucoma.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Bland-Altman plots depicting differences between techniques for H (A) and V (B) measurements.

 

CD as a function of AA for H (A) and V (B) measurements.