Abstract
Purpose :
Studies have established the ability of myopia control to slow the axial growth of the young myopic eye. Peripheral interferometry and autorefraction have shown diminishing treatment effect into the retinal periphery, however these techniques are limited to 30-40○, about a 2-3mm sagittal depth. There is a need for an inexpensive, wide-field method for assessing ocular size and shape to understand myopia control effects beyond the central retina. We developed a technique to extend the range of B-scan ultrasound to measure further into the retinal periphery, to about a 12-13mm sagittal depth.
Methods :
We acquired three horizontally oriented (central, temporal, nasal) and three vertically oriented images (central, superior, inferior) of the right eye of 10 young adult participants (8 female) using the ABSolu B-scan (Quantel Medical, Cournon-d’Auvergne, France). Participants had a mean (SD) age, refractive error, and axial length of 25.75 years (2.21), -1.51D (1.32), and 24.32mm (1.26), respectively. Images in the same orientation were manually merged in Photoshop, creating a complete montage of the eye in each meridian (Figure 1). A custom MATLAB program identified and exported the vitreo-retinal interface coordinates. We fit these with a conic section equation and computed the quadrant-specific vertex radius (r) and asphericity (Q) of the retinal contour.
Results :
Mean r (13.4mm (1.4)) did not differ by quadrant. Mean Q showed quadrant asymmetry. The temporal retina was the most spherical (0.040 (0.39)) and the degree of oblateness increased in the following order: superior (0.22 (0.15)), nasal (0.37 (0.20)), inferior (0.41 (0.17)) with significant differences between temporal and both nasal and inferior quadrants, and inferior more oblate than superior (p<0.025).
Conclusions :
B-scan ultrasonography can be extended to measure ocular shape beyond 30-40°, where peripheral contours may provide insights into ocular growth. The ability of extended range B-scan ultrasound to measure ocular size and shape conveniently and inexpensively may provide the ability to assess the effectiveness of myopia control both axially and globally.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.