Aberration-Driven Excimer Treatment In Severe Keratoconus Using Presbymax Reversal To Achieve Usable Vision Pre-Transplant

To describe the use of the PresbyMAX reversal option on the SCHWIND AMARIS excimer platform to deliberately modify spherical aberration in patients with grade 4 keratoconus, improving functional (“usable”) vision as a temporizing measure while awaiting corneal transplantation.

Tertiary cornea/refractive practice.

Patients with advanced keratoconus (grade 4) experiencing poor spectacle-corrected vision and/or contact lens intolerance and already proceeding toward keratoplasty were selected for a tissue-conservative excimer strategy aimed at optical quality improvement via higher-order aberration (HOA) manipulation, rather than full refractive normalization. Preoperative evaluation included manifest refraction, CDVA, tomography, and HOA analysis over a functionally relevant pupil. Treatments were planned to achieve a target shift in spherical aberration (direction and magnitude individualized) using the PresbyMAX reversal algorithm to alter corneal asphericity while minimizing tissue removal. Patients were counseled that the intent was bridging functional vision, not disease cure, and that keratoplasty plans remained unchanged.

Following treatment, patients demonstrated clinically meaningful improvement in functional vision sufficient for daily activities (e.g., improved reading/recognition and reduced visual distortion), with subjective gains in quality of vision. Improvements were attributed to a controlled change in spherical aberration and overall HOA profile rather than large refractive correction. No intraoperative complications were observed. Stability and safety parameters (refraction, topography/tomography, and corneal clarity) remained acceptable over early follow-up (18 months), supporting the role of this approach as a short- to mid-term visual rehabilitation option in carefully selected severe cases.