PRL implantation effective in patients with high myopia
Technique has not had serious complications, surgeon says.
Implantation of the Phakic Refractive Lens may be the technique of choice when treating patients with high myopia, according to one surgeon. The lens appears to be safe and effective for highly myopic patients whose eyes would not benefit from LASIK, he said.
Ioannis G. Pallikaris, MD, PhD, and colleagues at the University of Crete conducted a prospective study to evaluate the efficacy and safety of the Phakic Refractive Lens (PRL, IOLTECH) in highly myopic eyes.
“PRL implantation is recommended for myopia over –10 D and when LASIK cannot be performed due to thin corneas,” Dr. Pallikaris told Ocular Surgery News.
Slit-lamp photograph of an eye 6 months post PRL implantation (dilated pupil). The optic part of the lens can be distinguished from its haptics.
Images: Pallikaris IG
Dr. Pallikaris and colleagues examined 34 eyes of 19 patients treated for high myopia with implantation of the silicone PRL (PRL101). Eyes were evaluated for manifest refraction, uncorrected visual acuity, best corrected visual acuity, IOP and higher-order aberrations. Mean patient age was 29 years, mean preoperative spherical equivalent was –14.7 D, and mean preoperative refractive cylinder was –2.02 D. Patients were examined 1 day, 1 week, and 1, 3, 6, 9 and 12 months postop.
In postop examinations, Dr. Pallikaris and colleagues found that mean UCVA improved significantly from counting fingers preoperatively to 0.62 ± 0.28 at final follow-up (P < .001).="" all="" 34="" eyes="" experienced="" a="" gain="" of="" one="" to="" 12="" lines="" of="" va,="" a="" 6.2-line="" gain="" from="" preop="" to="">
Mean BCVA improved from 0.7 to 0.85 (P < .001).="" one="" eye="" lost="" two="" lines="" of="" preop="" bcva,="" eight="" maintained="" their="" preop="" bcva,="" and="" the="" remaining="" 25="" eyes="" experienced="" a="" one-="" to="" five-="" line="">
Seventy-nine percent of eyes were within ±1 D of target refraction, and 44% were within ±0.5 D of target refraction.
Dr. Pallikaris noted that theses results were better than those reported for other posterior chamber lenses.
Dr. Pallikaris and colleagues found that the PRL in a myopic eye does not cause a long-term increase in IOP.
An IOP increase attributable to residual viscoelastic was noted at 1-day postop and during the first month in six eyes because of corticosteroid response. IOP returned to preoperative levels after steroids were discontinued.
Dr. Pallikaris noted that corticosteroids were used in the study to prevent inflammation, but that surgeons may want to use nonsteroidal anti-inflammatory drugs to avoid IOP spikes in corticosteroid responders.
Quality of vision
Six patients complained of glare and halo at night, which decreased by 6 months after implantation. Five of these patients had pupils larger than 7 mm and the other patient’s pupil was 6 mm; Dr. Pallikaris said halo and glare were attributed to the use of a 5-mm lens.
He said that PRL implantation should not be contraindicated in all patients with large pupils.
“Not all patients experienced these night phenomena,” he said. “This implies that pupil size might not be the determining factor, or at least not the only one, for glare and halo at night.”
Wavefront aberrations were assessed in 15 eyes. Total higher-order root mean square was calculated for pupil diameters of 5 mm and 3 mm before implantation and at 1-year postop. Total higher-order aberration for eyes with 3-mm pupils did not change significantly from preop to postop (P = .08). The spherical aberration in 5-mm pupils was significantly decreased at 1 year. Dr. Pallikaris noted that this decrease could be a benefit for mesopic vision.
A small contrast sensitivity loss was also noted in some patients after PRL implantation.
“The majority of eyes experienced an improvement in contrast sensitivity and only a few patients had a contrast sensitivity loss. These patients did not detect any decrease in their quality of vision. They were very satisfied with the outcome,” he said. “Another study of contrast sensitivity pre- and post-PRL implantation is needed to detect any changes in patients’ quality of vision.”
Successful PRL implantation
For an experienced cataract surgeon, implantation of the Phakic Refractive Lens (PRL) is a simple procedure, according to Ioannis G. Pallikaris, MD, PhD. However, surgeons should make their manipulations gentle to avoid anterior capsular opacification due to contact between the PRL and the crystalline lens.
“The surgeon should fold and unfold the haptics of the lens, rather than pushing them downwards, in order to place them in the posterior chamber. The use of a manipulator is effective for this purpose,” he said.
Dr. Pallikaris also recommended the use of a high viscosity viscoelastic agent on the PRL to push the implant downward and a low viscosity one to widen the posterior chamber.
For Your Information:
- Ioannis G. Pallikaris, MD, PhD, can be reached at the University Hospital of Heraklion, Ophthalmological Clinic, P.O. Box 1352, Voutes, Heraklion, CR-71003 Crete, Greece; 30-81-3923-51; fax: 30-81-39-46-53; e-mail: firstname.lastname@example.org. Ocular Surgery News was unable to confirm whether Dr. Pallikaris has a direct financial interest in the products mentioned in this article or if he is a paid consultant for any companies mentioned.
- IOLTECH can be reached at Ave. Paul Langevin, BP5, 17053 La Rochelle, Cedex 9, France; 33-5-46-44-8550; fax: 33-5-46-44-8560; Web site: www.ioltech.com.