Optimal cross-linking outcomes

Respecting certain technical parameters in the application of corneal collagen cross-linking (CXL) will help physicians achieve greater consistency in outcomes when treating patients with keratoconus, Theo Seiler MD told delegates attending the joint ESCRS/EuCornea symposium on cross-linking. Since the introduction of CXL into clinics, many changes to the original Dresden protocol have been proposed, such as new light sources with shorter treatment times due to higher irradiances and new solutions with shorter imbibition times. “I think it is a good opportunity today to answer some of the questions that my colleagues frequently ask about the application of CXL in their clinics – how much energy to use, as well as questions around oxygen and riboflavin use,” he said. In terms of ultraviolet parameters, Dr Seiler said that lamps on the international market now offer UV-irradiances ranging from 3 mW/cm² to 45 mW/cm². However, using higher UV doses combined with shorter treatment times will reduce the efficacy of the treatment, said Dr Seiler. “Shorter operation times may be achieved by increasing the irradiance from 3mW/cm² up to 15mW/cm² without loss of efficacy if the application time is adjusted. The application of riboflavin in HPMC-solution shortens inhabitation time from 30 minutes to 10 minutes,” he said. For effective cross-linking to occur, a certain amount of oxygen is required to be present in the cornea, said Dr Seiler. Whereas the standard Dresden protocol occurs slowly enough for the oxygen to replenish, some accelerated CXL protocols consume too much oxygen too quickly.

Tags: corneal crosslinking