Best Candidates for Phakic EDOF IOLs?

Patients with presbyopia and moderate to high myopia between the ages of 45 and 55 years may be the best candidates for an extended depth of focus (EDOF) phakic intraocular lens, according to José F Alfonso Sánchez MD, PhD.

The add-on, ciliary body-supported EVO Viva implantable collamer lens (ICL; STAAR Surgical) preserves the natural crystalline lens and any residual accommodation. This may make the Viva safer than a lensectomy while providing better intermediate-range vision in many patients, Professor Alfonso said.

However, patients with inconsistent preoperative biometry readings, very small pupils, or who end up with total higher-order aberrations (HOAs) exceeding 0.30 microns could have problems. Lens sizing and clearance are also critical, requiring careful measurements before and during surgery to ensure proper lens positioning and vault, he stressed.

Developing the profile

Prof Alfonso developed this patient profile in part through a retrospective case series. It included 40 patients implanted bilaterally with the Viva lens. They were 45 to 55 years old with myopia between -2.00 D and -14.00 D and wore glasses. They had no cataracts, normal intraocular pressure, and corneal endothelial cell density of at least 2,000 cells per square millimetre.

Preoperatively, mean sphere was -6.34 D, and mean cylinder was -0.71 D, ranging from -3.00 D to 0.00 D. Mean crystalline lens rise (CLR) was 240 microns, ranging from -150 to +570 microns. Mean axial length was 26.74 mm, ranging from 23.29 to 30.00 mm.

During surgery, incisions were made on the steep meridian to reduce astigmatism, Prof Alfonso said. Intraoperative optical coherence tomography (OCT) was used to determine lens vault. If the vault of a horizontally implanted lens was more than 500 microns, it was rotated vertically. If the vault still exceeded 500 microns, the lens was exchanged for a smaller one to reduce vault.

Vision trade-off

After surgery, both monocular and binocular mean uncorrected distance vision improved substantially, from about 0.05 decimal preoperatively to 0.71 and 0.81 after surgery. However, best corrected distance visual acuity declined slightly from 0.96 to 0.93 monocularly and 0.98 to 0.97 binocularly.

Intermediate and near vision both improved. About two-thirds of patients were better than 0.50 or 20/40 at 40 cm binocularly, and all were better than 0.63 or 20/32 at 50 cm. “With the combination of the defocus of the lens and the patient accommodation capacity, a clinical outcome similar to an EDOF lens is achieved,” Prof Alfonso said, adding most patients did not need glasses to read.

As for safety, 40% of patients lost one or more lines of vision monocularly at one month after surgery, falling to 20% losing one line binocularly at the last follow-up, suggesting progressive neuroadaptation, Prof Alfonso said. “Most were satisfied with the results because independence from glasses compensates for the loss of distance vision.”

Aberrometry helps explain the clinical findings, Prof Alfonso said. Induction of -0.34 microns of spherical aberration allows near vision. On the other hand, increased coma and total HOAs reduce distance vision. If the aberrations are too high, the patient may be unhappy. In this series, nine patients had LASIK and one had a bilateral refractive lensectomy—with one Viva lens exchange pending, he reported.

Prof Alfonso made these comments at the 2024 ESCRS Congress in Barcelona.

José F Alfonso Sánchez MD, PhD is professor and head of the Department of Cornea and Lens, Fernández-Vega University Institute, Oviedo University, Oviedo, Spain. jalfonso@uniovi.es