Article
The ongoing evolution in refractive surgery: Phakic IOLs
Contemporary phakic IOLs are safe and effective for treating high ametropias. Further developments are expected to address some of the remaining needs, but the problem of complications due to interference with surrounding ocular tissues may never be overcome.
Take home
Contemporary phakic IOLs are safe and effective for treating high ametropias. Further developments are expected to address some of the remaining needs, but the problem of complications due to interference with surrounding ocular tissues may never be overcome.
By Cheryl Guttman Krader; Reviewed by Antonio A P Marinho, MD, PhD
Porto, Portugal-Phakic IOLs (PIOLs) are currently an important option for refractive surgery, and further advances may be expected in the next several years. However, it is impossible to predict what role PIOLs will have as a solution for ametropic correction in the more distant future, said Antonio A P Marinho, MD, PhD.
PIOLs overcome many of the limitations associated with laser vision correction and refractive lens exchange, Dr. Marinho explained, as PIOL implantation offers a predictable and stable method for correcting high ametropia that preserves accommodation, best spectacle-corrected visual acuity, and quality of vision.
Peering into the future
Looking ahead, it is likely that advances in PIOL surgery will overcome existing challenges in terms of expanding the range of correction and making implantation easier and safer. However, the problem of intimacy between the PIOL and surrounding ocular structures leading to complications will always remain.
Therefore, Dr. Marinho- professor of ophthalmology, University of Porto, and chairman, Department of Ophthalmology, Hospital Arrabida, Porto, Portugal-said his dream is for a future where innovation in lens surgery obviates the need for PIOLs. Dr. Marinho said his vision is that surgeons would refill the capsular bag with a gel material, the amount and viscosity of which would determine the refraction. The procedure would be done using a femtosecond laser to create a very small corneal incision (<1 mm) and through a very tiny anterior capsulorhexis that would be sealed with biological glue.
“The result would be the perfect IOL surgery that would preserve accommodation, not interfere with normal ocular structures, and cause no corneal changes,” he said.
Examining PIOL history
Reviewing the past and present state of PIOL surgery, Dr. Marinho noted that while refractive results have always been outstanding, long-term complications-including endothelial damage, pigment dispersion, angle closure, pupil ovalization, and cataract formation-have haunted these procedures since the beginning. Careful patient selection based on anatomic criteria is important for increasing safety. However, PIOL sizing errors are an underlying cause for many complications, and even with current approaches to implant selection based on measurements obtained with anterior segment optical coherence tomography (AS-OCT), sizing is imperfect.
Dr. Marinho demonstrated his point with his own data from a series of 113 eyes implanted with the acrylic angle-supported PIOL (AcrySof Cachet, Alcon). Despite the use of AS-OCT measurements, the PIOL rotated over time in 17% of eyes. Similarly, data from José F. Alfonso, MD, PhD, for a large series of eyes implanted with the sulcus-supported PIOL (Visian ICL, Staar) showed that size selection based on AS-OCT measurements did not totally avoid cases of low or exaggerated vault.
“We can expect to see better sizing approaches in the future. Currently, ours are not good enough,” Dr. Marinho said.
Going forward, Dr. Marinho noted that a new acrylic version of the foldable iris-supported PIOL (Artiflex, Ophtec) is being investigated in European clinical trials. This is a welcome development since the acrylic material has better biocompatibility than the currently available silicone model, he said.
Dr. Marinho also noted interest is trending toward favoring posterior chamber PIOLs over anterior chamber implants. Although the anterior chamber lenses are technically easier to implant, the potential for endothelial damage remains. Whether or not multifocal PIOLs will ever be introduced is questionable, and Dr. Marinho said he is not confident about the performance of such designs.
Antonio Marinho MD, PhD
Dr. Marinho is a consultant to Alcon and Ophtec.
