Relationship of Density, Depth, and Surface Irregularity of Superficial Corneal Opacification with Visual Acuity.

PURPOSE

To explore the relationship between the density, depth, and surface irregularity of superficial corneal opacities and vision.

METHODS

This prospective imaging study included 19 patients with unilateral superficial corneal opacification due to scarring post-microbial keratitis. Each eye underwent an assessment of uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contact lens corrected visual acuity (CLCVA), and Scheimpflug and anterior segment optical tomography imaging. Regression analysis was performed to detect the association between density, depth of scarring, and the surface irregularity in terms of higher order aberrations (HOA), and keratometry and UCVA, CLCVA, and the difference between BSCVA and CLCVA.

RESULTS

The mean logMAR UCVA, BSCVA, and CLCVA were 0.76, 0.35, and 0.28, respectively. The corneal scars had a mean thickness of 158.7 ± 61 µ and density of 65.73 ± 24.46 GSU. Bivariate analysis model for UCVA showed an association with Z secondary astigmatism ( = 0.02), Z quadrafoil ( = 0.01), combined coma Z ( = 0.03), and combined HOA Z-Z ( = 0.045), out of which Z Quadrafoil ( = 0.04) was most significant with multivariate analysis. Bivariate analysis for BCVA-CLVA showed association with Z coma horizontal ( = 0.04), Z oblique trefoil ( = 0.02), Z primary spherical aberration ( = 0.008), and Z  ( = 0.007), out of which Z horizontal coma ( = 0.04) and Z spherical aberration ( = 0.009) were significant on multivariate analysis. Change in densitometry, corneal thickness, epithelial:stromal reflectivity ratio, scar depth, and keratometry did not show any significant association with UCVA, BSCVA-CLCVA, or CLCVA.

CONCLUSION

In superficial corneal stromal scarring, deranged surface irregularity parameters like higher-order aberrations affect the final visual acuity more than the depth or density of the opacity.