March 2014

 

REFRACTIVE SURGERY

 

Long-term strategy for phakic IOLs


by Rich Daly EyeWorld Contributing Writer

 
   
Clinical images of cataract

Clinical images of cataract that has developed in a phakic IOL recipient. Cataract development is a particular concern in posterior chamber phakic IOL patients due to the close proximity of the implant to the human crystalline lens. If it touches then there is a high likelihood of cataract development.

Source: Uday Devgan, MD

Surgeons develop plans to respond to the long-term complications of phakic IOLs that emerging research and clinical experience have identified

Consistent follow-up and patient education are more important than ever as early phakic IOL recipients enter the age range for common eye-related conditions, according to surgeons.

Premature development of a cataract or damage to the corneal endothelium remain the leading long-term phakic IOL concerns for Uday Devgan, MD, in private practice, Los Angeles, and associate clinical professor of ophthalmology, Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles.

Cataract development is particularly important in posterior chamber phakic IOLs (PC PIOLs) and when the PC PIOL is in close proximity (less than 0.5 mm) to the human crystalline lens, he said.

"If it touches then there is a high degree of cataract development," Dr. Devgan said. "We want to avoid inducing a cataract in a young, highly myopic patientlike the patients who receive PIOLsdue to the higher risk of retinal detachment and loss of accommodation with phacoemulsification."

Damage to the corneal endothelium is more common in anterior chamber phakic IOLs (AC PIOLs) since the AC PIOL is in closer proximity.

Plan for tracking

Jeffery D. Horn, MD, in private practice, Nashville, Tenn., routinely compares AC PIOL recipients' corneal endothelial cell counts to preoperative measurements and checks patients for signs of cell morphology using spectral microscopy. The follow-up is limited to annual exams if the patient has good corneal endothelial cell counts (ECCs), no obviously concerning signs, and no unusual trend in cell loss.

When annual ECCs reveal a significant and persistent drop in cell density, Dr. Devgan said, then removal of the PIOL may be indicated.

Dr. Horn also checks the actual position of the lens. Although iris claw lenses tend not to change, angle-supported phakic IOLs could have differences due to the patients' vault, which could leave a lens closer to the corneal endothelium and potentially lead to loss of endothelial cells. "In patients with greater percentages of cell loss from one visit to the next or who have lenses that under slit lamp examination or by OCT you can see the lens getting closer to the cornea, you may want to follow them more closelyevery six months," Dr. Horn said.

Cases of shallow ICL vaults are the one instance in which Robert P. Rivera, MD, in private practice, Draper, Utah, follows patients more closely than routine annual refractive testing.

"The typical ICL related cataract is anterior subcapsular in nature and is found in association with patients with shallow or flat vaults," Dr. Rivera said.

Although PIOL patients with cataracts are found to have flat vaults, the majority of his PIOL patients with flat vaults have yet to develop them, he said.

Other conditions Dr. Horn has seen arise in PC PIOL patients include intraocular pressure spikes, LPIs that close, and poorly sized lenses that may require replacement.

"They are commonly removed if there are issues with elevated pressure and pupil lock," Dr. Horn said.

Patients predisposed to glaucoma generally should not receive these lenses but if such patients do have a PIOL, they require annual gonioscopy and pressure checks. Treatment protocols for patient who start to develop elevated pressure are the same as for any other patient with suspected glaucoma, Dr. Horn said.

Extending life of PIOLs

One of the selling points of PIOLs is that they require little to no maintenance compared to traditional contact lenses. But ocular trauma can cause the PIOL to shift, become dislodged, and even come into contact with the crystalline lens and induce a cataract. The most common traumas that Dr. Devgan has seen in these patients are due to airbag injuries during car accidents. Another long-term issue is the higher chance of visually significant cataract formation. Recent research found the rate of development of a significant cataract was slightly less than 5% within eight years postop.1

"We are finding patients with PC IOLs seem to be developing visually significant cataracts at a higher rate than was seen in the FDA trial," Dr. Horn said.

Cataracts tend to occur in the higher myopes and patients over 40. Particularly in those patients, he monitors visual acuity, conducts functional vision tests, and monitors the vault of the lens with ultrasound biomicroscopy or anterior segment optical coherence tomography.

Anterior subcapsular cataract formation is the only time Dr. Rivera recommends a phakic IOL explantation.If the vault has become low, he considers exchanging the ICL for a longer one in order to increase the vault, which may allow the patient several more years of excellent unaided vision.

A key to long-term success is patient education.

"It is important to educate patients as to the need for ongoing follow-up given that their eyes remain genetically, if not physiologically, nearsighted," Dr. Rivera said. "With that comes an increased incidence of retinal pathology, glaucoma, and other issues; the better educated patients are, the more likely they will be to present routinely or to come in sooner if they notice any changes in their vision."

Reference

1. Igarashi et al. Eight-year follow-up of posterior chamberphakicintraocular lens implantation for moderate to high myopia. Am J Ophthalmol. 2013 Nov 13. pii: S0002-9394(13)00728-9. doi: 10.1016/j.ajo.2013. 11.006. [Epub ahead of print]

Editors' note: Dr. Devgan has financial interests with Alcon (Fort Worth, Texas). Dr. Horn has financial interests with Alcon. Dr. Rivera has financial interests with STAAR Surgical (Monrovia, Calif.).

Contact information

Devgan
: devgan@gmail.com
Horn: jeff.horn@bestvisionforlife.com
Rivera: rpriveramd@aol.com

Related articles:

Expanding options for phakic lenses by Rich Daly EyeWorld Contributing Writer

Phakic IOL explantation safe, reversible approach by Erin L. Boyle EyeWorld Senior Staff Writer

Phakic IOLs and peripheral iridotomy by Michelle Dalton EyeWorld Contributing Writer

Phakic lenses today by Enette Ngoei EyeWorld Contributing Editor

Phakic IOL update: Current technology, new uses, advantages, and drawbacks by Matt Young EyeWorld Contributing Editor

Phakic IOLs by Matt Young EyeWorld Contributing Editor

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