Abstract
Purpose :
Pathologic myopia is a leading cause of blindness worldwide. Current trends indicate that by 2050, 10% of the global population will exhibit high myopia and be at significantly increased risk for developing pathologic myopia. Standard clinical ophthalmic measurements, including refractive error (RE) and axial length (Axl), can identify the existing level of myopia but cannot predict disease progression. Myopia is known to induce microstructural changes in the posterior sclera and evidence exists that the anterior sclera microstructure is also affected. Quantitative ultrasound (QUS) methods can characterize tissue microstructure and may be sensitive to myopia-induced changes in the anterior sclera.
Methods :
A novel high-frequency (80MHz) point-of-care (POC) ultrasound instrument was built to collect radiofrequency (RF) echo data from the anterior sclera of patients in vivo. Eighty-five subjects with varying levels of myopia were recruited for this study. After obtaining standard ophthalmic measurements, both eyes were scanned with the POC instrument. RF data were processed with QUS methods to obtain five parameters relating to tissue microstructure and stiffness. Correlations between QUS parameters and RE or Axl were evaluated using linear and multi-linear regression. Eyes were categorized into four groups based on RE or presence of staphyloma. A quadratic discriminant analysis classifier was trained using the QUS parameters to classify each eye. Classifier performance was evaluated by computing the area under the receiver-operating characteristic curve (AUC).
Results :
Three QUS parameters were individually correlated with RE and two correlated with Axl (p<0.05). Multilinear regression revealed statistically significant correlations between the QUS parameters and RE (R=0.38, p<0.001) and Axl (R=0.35,p<0.001). The classifier achieved satisfactory performance in classifying eyes overall (AUC=0.64) and was most accurate at classifying pathologic myopia eyes (AUC=0.71).
Conclusions :
QUS parameters characterizing the microstructural properties of the anterior sclera correlate with level of myopia and are particularly sensitive to changes associated with the formation of a posterior staphyloma. One year follow-up scans of the same subjects will reveal the potential for QUS parameters to predict myopia progression and imminent risk of staphyloma formation.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.