The Power of Four

Since implementing keratorefractive lenticule extraction (KLEx) in refractive surgery, corneal lenticules are often considered nothing more than waste products, usually disposed of after the procedure. However, according to Suphi Taneri MD, this could be a trend set to change in the near future.

Four novel and different procedures considering corneal lenticule use are under investigation as possible treatment options for specific conditions.

Small-incision corneal intrastromal lenticule implantation for hyperopia correction (FILI) was the first mentioned, an effective technique where a lenticule extracted from a donor myopic eye after a KLEx procedure is subsequently implanted into a hyperopic eye.

This field of intrastromal lenticule implantation was founded by Drs Sri Ganesh and Sheetal Brar, who dedicated an entire decade to the development. It is a surgical technique in evolution, an elegant method that has shown interesting and positive results in the outcomes of a five-year study. This technique uses untreated human tissue, unlike the second procedure, Dr Taneri explained.

While some patients around the globe may not approve of porcine lenticule implantation, he added, small-incision lenticular intrastromal keratoplasty (LIKE) uses a denatured lenticule from a porcine eye graft, which is first cross-linked and then inserted in the cornea of a patient with keratoconus. This lenticule is much stiffer than the keratoconic stroma and can be inserted in a corneal pocket to stabilise and flatten an ectatic cornea.

The third technique, pioneered by Dr Aylin Kılıç, comes with the three-year study results on allogenic inlays made from corneal donor tissue, designed to increase depth of focus of presbyopic patients. The allogenic inlay inserted is so small and biocompatible it is almost invisible—even to a slit lamp analysis, allowing the eye to gain a broad defocus curve of -4.0 D reading distance.

Lenticule rotation was the last technique Dr Taneri mentioned, a principle developed by Dr Jesper Hjortdal and reported on a clinical level for the first time by Dr Pavel Stodůlka for treating extreme astigmatism. The technique aims to create a lenticule with half of the manifest refractive cylinder and rotate it 90 degrees—without removing any corneal tissue from the patient.

Clinical cases presented showed no sign of opacification after eight months, along with a myopic shift, probably due to the dissection of the corneal lamellae. The myopic shift is acceptable and, in some cases, beneficial for the hyperopic patient.

Lenticule implantation—either human, allogenic, or cross-linked—or the rotation of the patient’s lenticule inside the corneal pocket are at the base of four promising approaches for four special indications, such as presbyopia correction, ectasia, hyperopia, and extreme corneal astigmatism.

Dr Taneri presented during the 2024 ESCRS Winter Meeting in Frankfurt.

Suphi Taneri MD is the Director of the Center for Refractive Surgery Muenster, Germany. taneri@refraktives-zentrum.de