Central corneal edema caused by short periods of closed eye scleral lens wear appears to worsen as the fluid reservoir thickness increases, a study in Contact Lens & Anterior Eye suggests. Still, the edema isn’t as bad as it is with overnight scleral lens wear, the researchers add.

The team from Australia examined the relationship between central post-lens fluid reservoir thickness and central corneal edema during short-term closed eye scleral lens wear and compared the findings with open eye and overnight lens wear.

The study enrolled ten participants who were approximately 30 years old with normal corneas. The patients wore scleral lenses under closed eye conditions on separate days with an initially low (160 ± 7μm), medium (494 ± 17μm) or high (716 ± 16 μm) central post-lens fluid reservoir thickness. The researchers measured epithelial, stromal and total corneal edema using OCT immediately after lens application and following 90 minutes of wear, prior to lens removal. The data was then compared with both open-eye scleral lens induced corneal edema and a theoretical model that measured overnight closed-eye scleral lens wear.

The investigators found central corneal edema was primarily stromal in nature and increased as the fluid reservoir thickness increased. The mean total corneal edema was 3.86±0.50%, 4.71±0.28% and 5.04±0.42% for the low, medium and high thickness conditions, respectively.

The study also reported a significant difference in stromal and total corneal edema between the low and high fluid reservoir thickness conditions only. Also of note: theoretical modeling overestimated the magnitude of central corneal edema and the influence of fluid reservoir thickness upon corneal edema during closed eye conditions.