Relationship of ocular and systemic factors to the visibility of choroidal-scleral interface using spectral domain optical coherence tomography

Purpose: To assess the visibility of the choroidal-scleral interface (CSI) from spectral domain optical coherence tomography (SD-OCT) and evaluate the ocular and systemic factors influencing the visibility of CSI in healthy eyes from population-based Malay sample.

Methods: Participants were consecutively recruited from the population-based Singapore Malay Eye Study-2 (SiMES-2). SD-OCT images were obtained by Spectralis OCT with enhanced depth imaging (EDI) mode. Visibility of CSI was assessed by a grading system ranging from 0 to 2 scores. The reliability of choroidal thickness measurement in different grades of CSI visibility was assessed using intraclass correlation coefficient. Ordinal regression analyses were performed to evaluate a range of ocular and systemic factors influencing the visibility of CSI.

Results: A total of 176 healthy eyes were analysed, and 59.1% of our subjects had well-defined CSI (score 2), 8.5% had poorly defined CSI (score 0), and 32.4% had CSI between well and poorly defined (score 1). The reliability of subfoveal choroidal thickness measurement decreased with each grade of CSI visibility score. Decreased axial length (AL) (estimate of ordinal regression [OR] = 0.465, p = 0.003), thicker retinal thickness (estimate of OR = -0.030, p = 0.004), younger age (estimate of OR = 0.045, p = 0.030) and diabetes (estimate of OR = -0.746, p = 0.004) were associated with lower CSI visibility score.

Conclusions: Only 60% of normal healthy eyes had well-defined CSI from SD-OCT images. Our data suggest that choroidal thickness measurements can be substantially affected by the visibility of CSI. The visibility of CSI varies with AL, retinal thickness, age and diabetes.