Foldable phakic IOL shows positive outcomes

January 1, 2009

The angle-supported phakic IOL (AcrySof, Alcon Laboratories) is being evaluated for the treatment of moderate to high myopia in three phase II and III clinical trials in Europe and North America enrolling 360 patients. Data from a 3-year visit in 104 eyes show excellent stability, predictability, and vision outcomes with a low rate of adverse events.

Key Points

"The haptics are soft and flexible, conforming well to the shape of the angle as they rest gently in the iris recess while keeping the IOL vaulted so that it lies at a safe distance from the corneal endothelium and crystalline lens," Dr. Lane said.

The implant has a 6.0-mm optic and is being investigated in a dioptric power range from –6.0 to –16.5 D. Four overall lengths are available-12.5, 13.0, 13.5, and 14.0 mm-with the aim of providing a better custom fit based on an individual's anterior chamber anatomy.

The pooled data reported by Dr. Lane were from a European phase III study (190 patients), a Canadian phase III study (120 patients), and a United States phase II study (50 patients). Together, these multicenter trials have enrolled 360 subjects; data were available from the 3-year visit for 104 subjects.

Patients enrolled in the studies had to be aged more than 18 years, and in the United States and Canada, a maximum age limit was set at 49 years. Patients had to demonstrate stable moderate to high myopia with no more than 2 D of astigmatism, a mesopic pupil size no greater than 7 mm, and an anterior chamber depth of at least 3.2 mm. Patients with a personal or family history of glaucoma were excluded, and age-dependent endothelial cell density criteria were created for patient selection.

At the 3-year visit, 46% of eyes achieved distance uncorrected visual acuity (UCVA) of 20/20 or better, 73% saw 20/25 or better without correction, and 97% achieved 20/40 or better. Best-spectacle corrected visual acuity (BSCVA) was 20/20 or better in 81% of eyes, 20/25 or better in 98%, and 20/40 or better in 100%.

The refractive results showed excellent stability and predictability, Dr. Lane said. Manifest refraction spherical equivalent (MRSE) was –10.41 D preoperatively, –0.25 D at 1 month, and –0.24 D at 3 years. The achieved MRSE was within 1.0 D of target in 91% of eyes and ±0.5 D in 79% of eyes, he reported.

"Ninety-five percent of patients said they would have the same lens implanted again," Dr. Lane added.

No eyes lost more than 2 lines from their preoperative BSCVA and only 1% had a 2-line loss. Almost 60% of eyes benefited with a 1-line or greater increase in BSCVA.

Endothelial safety is being evaluated with images being read by a central reading center and includes analyses for changes in central and peripheral (superior nasal) endothelial cell density from 6 months forward and in cell morphology. From 6 months to 3 years, central endothelial cell density decreased by an average of only –0.41% and change in the peripheral cell count was –1.11%. Data for coefficient of variation and percent of hexagonality also showed minimal change, according to Dr. Lane.

No significant surgery-related complications were found, including no cases of endophthalmitis, hyphema, hypopyon, lens dislocation, cystoid macular edema, pupillary block, or retinal detachment. Elevated IOP at more than 1 month after surgery that required treatment was the most frequent adverse event, occurring in 10 eyes (2.8%).

"Eight of the 10 cases of elevated IOP were due to steroid response, and in no case was the IOP elevation persistent," Dr. Lane said.

Six eyes (1.7%) developed synechia. No cases of pupil ovalization occurred. Cataract developed in seven (1.9%) eyes. In three cases, the opacity was thought to be related to lens touch during implantation surgery, whereas in the other eyes, the etiology was unknown, considered age-related, or associated with concurrent ophthalmic disease.

A secondary re-intervention or other surgical treatment was performed in a total of 13 eyes.

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