Long-Term Effectiveness of Scleral Lens Treatment in the Management of Keratoconus: A Systematic Review

This systematic review evaluates the long-term effectiveness of scleral lenses in improving visual outcomes, patient satisfaction, and safety in patients with keratoconus. A systematic search of six databases (PubMed, Embase, Web of Science, Scopus, Cochrane Library, and MEDLINE) was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The inclusion criteria included studies with more than or equal to three months of follow-up, included a minimum of 20 keratoconus patients, published after year 2020 and outcomes reporting visual acuity, comfort or quality of life. Methodological quality was assessed using the Newcastle-Ottawa Scale and Murad et al. case series tool. Five studies (463 eyes) met the inclusion criteria. Scleral lenses consistently improved best-corrected visual acuity (BCVA) across studies, with visual gains from baseline logMAR 0.50-0.53 to post-treatment logMAR 0.08-0.09. Significant improvements in vision-related quality of life (National Eye Institute Visual Function Questionnaire (NEI-VFQ) scores) were observed in validated assessments. Complications were infrequently reported but included lens handling issues (10.4%-63%), fogging (58%), and physiological events (e.g., corneal epitheliopathy). Long-term follow-up indicated that 14.6% of the patients experienced worsening visual acuity due to keratoconus progression. Methodological quality was variable, with limitations including variable outcome reporting and limited follow-up duration.  Scleral lenses provide substantial and sustained improvements in visual acuity and quality of life for keratoconus patients, particularly those with advanced disease. However, the evidence is limited by methodological shortcomings and a lack of long-term controlled studies. Future research should prioritise randomised trials with standardised reporting and longer follow-up to better assess complications and durability of outcomes.