Fluid reservoir thickness and corneal oedema during closed eye scleral lens wear

Purpose: To examine the relationship between central post-lens fluid reservoir thickness and central corneal oedema during short-term closed eye scleral lens wear, and to compare these empirical oedema measurements with open eye lens wear data and current theoretical modelling for overnight scleral lens wear. Methods: Ten participants (mean +/- standard error 30 +/- 1 years) with normal corneas wore scleral lenses (Dk 141 x 10(-11) cm(3) O-2 (cm)/[(sec.)(cm(2))(mmHg)) under closed eye conditions on separate days with an initial central post-lens fluid reservoir thickness considered to be low (160 +/- 7 mu m), medium (494 +/- 17 mu m), or high (716 +/- 16 mu m). Epithelial, stromal, and total corneal oedema were measured using high-resolution optical coherence tomography immediately after lens application and following 90 min of wear, prior to lens removal. Data were compared to open eye scleral lens induced corneal oedema and a theoretical model of overnight closed eye scleral lens wear (Kim et al., 2018). Results: Central corneal oedema was primarily stromal in nature and increased with increasing fluid reservoir thickness; the mean total corneal oedema was 3.86 +/- 0.50%, 4.71 +/- 0.28% and 5.04 +/- 0.42% for the low, medium, and high thickness conditions, respectively. A significant difference in stromal and total corneal oedema was observed between the low and high fluid reservoir thickness conditions only (both p <= 0.01). Theoretical modelling overestimated the magnitude of central corneal oedema and the influence of fluid reservoir thickness upon corneal oedema during closed eye conditions. Conclusion: Scleral lens induced central corneal oedema during closed eye lens wear increases with increasing fluid reservoir thickness, but at a decreased rate compared to theoretical modelling.

Automated summary

The study found that central corneal oedema during short-term closed eye scleral lens wear is primarily stromal in nature and increases with increasing fluid reservoir thickness. There was a significant difference in stromal and total corneal oedema between low and high fluid reservoir thickness conditions. Theoretical modelling overestimated the magnitude of central corneal oedema and the influence of fluid reservoir thickness upon corneal oedema during closed eye conditions.