While physicians apply scleral lenses to aid in the management of conditions such as severe dry eye disease and corneal ectasias, new research suggests that their use is correlated with an increased central corneal thickness (CCT) when applied to patients with existing ocular surface disease (OSD).
Researchers at the University of Southern California conducted a retrospective study to examine the effects of scleral lens wear on CCT and intraocular pressure (IOP) in patients with OSD. All 25 patients recruited for the study had been diagnosed with dry eye disease and categorized as either graft vs host disease, Sjögren’s syndrome, Stevens-Johnson syndrome, or general dry eye syndrome. The researchers examined CCT and IOP measurements that were obtained during the initial scleral lens consultation and CCT and IOP that were obtained during follow-up visits immediately after scleral lens removal where visual acuity was also measured.
A statistical analysis compared initial and follow-up corneal thicknesses, comparing the change corneal thickness (ΔCCT) with any changes in visual acuity. They also documented if any ΔCCT existed in various types of OSD, and the relationship between ΔCCT and scleral lens diameter. In addition, the researchers compared average wear time with both CCT and IOP.
When comparing the average difference between initial CCT measurements and follow up CCT, a significant increase of 1.01% (P <.05) was found. Although no corneal edema was noted on clinical examination in any subjects, the researchers speculate that corneal swelling may be statistically significant, but not clinically significant.
The researchers noted no statistically significant differences between ΔCCT and visual acuity, nor any significant difference between corneal thickening and underlying dry eye etiology. No significant correlation was made between either ΔCCT and wear time or IOP and wear time. No significant correlation between CCT and IOP, or lens wear and IOP were found during statistical analysis. Likewise, the relationship between ΔCCT and scleral lens diameter was not statistically significant.
The study suggests an increased risk of corneal hypoxia for patients with OSD wearing scleral lenses. However, the researchers note that more studies are needed to better understand how CCT may be affected by dry eye as well as any association with glaucoma development.
Shahnazi KC, Isozaki VL, Chiu GB. Effect of scleral lens wear on central corneal thickness and intraocular pressure in patients with ocular surface disease. Eye Contact Lens. 2020;46(6):341-347. doi: 10.1097/ICL.0000000000000670.