Refractive lenticule implantation is providing good results as a technique for managing unilateral aphakia.
Take-home message: Refractive lenticule implantation is providing good results as a technique for managing unilateral aphakia.
Reviewed by Osama I. Ibrahim, MD, PhD
Alexandria, Egypt-Early experience with refractive lenticule implantation (Relimp) indicates it is a promising approach for unilateral aphakia management, according to Osama I. Ibrahim, MD, PhD.
The procedure involves small-incision lenticule extraction (SMILE; performed with the VisuMax femtosecond laser, Carl Zeiss Meditec) to correct astigmatic error followed by insertion of a fresh lenticule from a myopic donor to increase corneal thickness and correct the high hyperopic error.
Dr. Ibrahim has been working on its development with Ibrahim Sayed-Ahmed, MD, and Moones Abdalla, MD.
“SMILE is a new procedure originally introduced for correction of myopia, and now we are pleased to be applying it to manage different refractive errors,” said Dr. Ibrahim, professor of ophthalmology and chief of cornea and refractive surgery, Alexandria University, Alexandria, Egypt.
“Outcomes with [refractive lenticule implantation] have been encouraging, and these patients with marked hyperopic anisometropia have been very satisfied,” he said. “They are less demanding than refractive surgery patients, and so rather than expecting good uncorrected visual acuity, they are grateful even if they need to wear glasses postoperatively to correct some residual refractive error.”
A number of challenges are confronted when designing a procedure that adds tissue to the cornea to correct hyperopia, Dr. Ibrahim explained.
It needs to steepen the anterior corneal surface while avoiding the resistance of the intact Bowman’s layer and avoiding bulging of the posterior corneal surface. Proper centration and stability of the lenticule is also critical, and the procedure must allow for maintenance of corneal physiology and passage of fluids through the lenticule.
In addition, there are the refractive issues to consider, including how to attain refractive accuracy by correcting the associated astigmatism and designing a lenticule that will correct the existing hyperopic error.
As described by Dr. Ibrahim, all of those issues have been taken into account in developing refractive lenticule implantation. The following case illustrates the technique.
A patient with unilateral aphakia presented with MRSE of +12 +4 @ 80 ( +16 -4 @170) and undergoes SMILE for +2 -4 @170 correction. Using a donor lenticule obtained from a patient who underwent SMILE for a high myopic error of -13.75 D, the patient with unilateral aphakia is left almost plano.
“Postoperative uncorrected visual acuity was 0.4, which is one line more than his preoperative best-corrected visual acuity,” Dr. Ibrahim said.
Postoperative follow-up of patients who have undergone refractive lenticule implantation show good corneal clarity on the first day after surgery. This patient has been followed up for almost 1 year with stability of refraction and maintenance of corneal clarity. The cornea became progressively thinner and slightly less steep. At 1 year he was - 1.0 - 1.0 @ 80, with BSCVA of 0.5.
Describing the technique, Dr. Ibrahim said that the donor lenticule is placed in a contact lens with a drop of antibiotics prior to insertion in the recipient’s eye. It is important to note the orientation so that it will be properly positioned on transfer.
“The donor lenticule needs to be placed ‘upside down’ in the recipient eye, with the planar surface on the bottom and the convex surface facing anteriorly,” he said. “This orientation will achieve the desired steepening of the anterior cornea and prevent bulging of the posterior cornea.”
The surgery in the recipient eye requires three large (4 mm) arcuate incisions that will release the Bowman’s layer and allow the anterior surface of the cornea to steepen properly.
The next step is dissection of a lenticule to correct the astigmatic error, representing the difference in refraction between the lenticule that will be inserted and the patient’s existing refractive error.
Dr. Ibrahim noted that centration of the donor lenticule in the recipient eye is easy using the SMILE mark.
Osama I. Ibrahim, MD, PhD
This article was adapted from Dr. Ibrahim’s presentation at Refractive Subspecialty Day during the 2015 meeting of the American Academy of Ophthalmology. Dr. Ibrahim is a consultant to Carl Zeiss Meditec.