Purpose <p>To review the optical principles of contact lens correction in keratoconus, with a focus on residual ocular wavefront error and its impact on vision performance.</p> Findings <p>Corneal rigid gas permeable (RGP) contact lenses, commonly used in keratoconus management, often fail to improve vision quality to levels observed in non-diseased eyes due to residual higher-order aberrations (HOAs), primarily originating from posterior corneal irregularity. Dependent on the nature of the residual wavefront error, various lens parameter modifications, including optic zone asphericity, base-down prism and scleral lens vault adjustments, can improve vision outcomes. Wavefront-guided corrections have demonstrated potential to provide vision quality equivalent to that of healthy eyes, particularly when sufficient time is allowed for neural adaptation.</p> Summary <p>This review examines the optical characteristics of the cornea in keratoconus, including the induction of elevated ocular wavefront errors. Challenges relating to optical correction with contact lenses are discussed, with an exploration of the origins of residual HOAs and their subsequent impacts on vision quality and quality-of-life. A range of contact lens modalities and parameter modifications are discussed, with evidence supporting their efficacy in reducing residual ocular wavefront error. Emerging data on wavefront-guided corrections are presented, along with future directions for personalised optical corrections tailored to individual patient presentations.</p>