The central fluid reservoir depth of a scleral lens has the most significant impact on lens decentration, according to a study.
A greater initial fluid reservoir depth leads to more lens decentration, especially inferiorly. In contrast, variations in lens thickness, mass, or the addition of a peripheral fenestration have minimal effect on lens centration when controlling for fluid reservoir depth.
The study included 10 young, healthy participants who underwent a series of short-term (90 minutes) open-eye scleral lens trials. Throughout these trials, the scleral lens parameters were kept constant, while variations in central fluid reservoir depth (ranging from 144 to 726 μm), lens thickness (150 to 1200 μm), lens mass (101 to 241 mg), and lens design (with or without a 0.3 mm peripheral fenestration) were introduced. Lens decentration was assessed using over-topography maps.
On average, scleral lens centration shifted by less than 0.10 mm during 90 minutes of wear. However, lenses with medium and high central fluid reservoir depths experienced 0.17 mm more temporal and 0.55 mm more inferior decentration compared to those with low reservoir depths (P < 0.001). Changes in lens thickness or the addition of a peripheral fenestration did not cause notable alterations in centration (<0.10 mm) when fluid reservoir depth was accounted for. Central fluid reservoir depth was the strongest predictor of both horizontal and vertical lens decentration, accounting for 62-73% of the variation, while lens thickness and mass accounted for 40-44%.
Reference
Fisher D, Collins MJ, Vincent SJ. The effect of lens and fitting characteristics upon scleral lens centration. Ophthalmic Physiol Opt. 2024;doi: 10.1111/opo.13367. Epub ahead of print. PMID: 39033320.
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