Improving limbal fit in scleral lenses: challenges, advances, and clinical strategies

Scleral lens practitioners frequently observe that the limbal fit of contemporary scleral lens designs is suboptimal. Inadequate limbal fit can lead to adverse corneal health findings, including limbal staining, limbal microcysts, conjunctival prolapse, neovascularisation, and limbal stem cell deficiency. These complications may compromise patient comfort and long-term corneal health, potentially affecting limbal stem cells through hypoxic or mechanical stress. Consequently, they may affect the long-term suitability for scleral lens wear of the patient and require the practitioner to carefully assess the risks and benefits of continued use. Achieving optimal limbal fit in clinical practice remains challenging due to the lack of clear definitions, mismatch between scleral lens limbal zone design and underlying limbal anatomy, and lens decentration. This review summarises recent advances in understanding human limbal shape, with particular emphasis on the concept of the topographical limbus derived from anterior segment imaging techniques, including corneoscleral topography, anterior segment optical coherence tomography, and the ocular impression technique. In addition, potential strategies to improve limbal fit are discussed, including the establishment of clearer terminology for the limbus and limbal fluid reservoir thickness, incorporation of imaging-derived limbal measurements into scleral lens design, consideration of oval limbal zone designs, and optimisation of lens centration.