Evolution and Concept of Doughnut Refractive Lenticule Transplantation

Keratoconus, particularly in its advanced stages, presents a formidable clinical challenge [1]. Patients with extremely thin corneas, stromal opacity, and decentered cones often fall outside the safe parameters for tissue preserving interventions such as corneal cross linking, INTACS, CAIRS, or DRLT. These procedures generally require a minimum residual stromal thickness and a relatively clear optical zone to ensure safety and effectiveness. In such extreme cases, only DALK (provided no involvement of descemet membrane by opacity) or PKP remain viable surgical options, as they can still be performed even in severely thinned or opacified corneas [2]. However, DALK and PKP come with significant limitations, including the risk of graft rejection, prolonged suture dependence, interface haze, donor-related variability, and long visual recovery with uncertain refractive outcomes [3]. These challenges underscore the ongoing need for innovative, safer alternatives in earlier stages of keratoconus that do not yet warrant full thickness corneal transplantation.