For patients who undergo femtosecond laser-assisted in situ keratomileusis (FS-LASIK) surgery, a decrease in their corneal epithelial thickness is linked with myopic regression, according to a new study in BMC Ophthalmology.

Researchers enrolled 84 eyes of 54 patients diagnosed with myopic regression after FS-LASIK. The individuals were treated with topical steroid and anti-glaucoma drugs. The investigators measured corneal epithelial thickness with OCT before and after treatment.

The study divided participants into three groups based on their corneal epithelial thickness at the time of myopic regression. The investigators conducted regression analyses to investigate the association between corneal epithelial thickness, visual acuity and refraction. Treatment success was defined as improvements of two or more lines in uncorrected distance visual acuity and 0.5D or more in refraction or K.

Researchers observed a decrease in corneal epithelial thickness with greater change in the center as myopic regression subsided during medical treatment. A subgroup with the thickest epithelium (62μm or greater) showed a higher success rate and greater changes in refraction and vision. Additionally, a reduced magnitude of corneal epithelial thickness showed significant correlations with changes of K and refractive error.

Of note: corneal epithelial thickness was a significant factor in the success of treatment, and corneal epithelial thickness greater than 60.5μm had 81.5% sensitivity and 84.2% specificity for the success of medical treatment.

“This study suggested that corneal epithelial thickness plays a role in deciding whether patients would respond to medical treatment,” the researchers wrote in their paper. “We believe that routine measurement and monitoring of corneal epithelial thickness could be useful in subjects seeking laser refractive surgery to understand the pathogenesis of myopic regression as well as to optimize treatment strategy.”

Ryu IH, Kim WK, Nam MS, et al. Reduction of corneal epithelial thickness during medical treatment for myopic regression following FS-LASIK. BMC Ophthalmology. July 18, 2020. [Epub ahead of print].