MULTIFOCAL LENS

An aspheric treatment for the light adjustable lens (LALR, Calhoun Vision) following the first refractive adjustment can improve uncorrected near and intermediate vision without sacrificing uncorrected distance visual acuity, said Fritz Hengerer MD, Ruhr University Eye Hospital, Bochum, Germany. “Using this approach, the dominant eye can be adjusted to emmetropia while an aspheric treatment is applied to the non-dominant eye to improve near and intermediate visual acuity,” Dr Hengerer said at the XXXI Congress of the ESCRS in Amsterdam.

The LAL is a foldable three-piece silicone IOL with blue PMMA modified C haptics. The optic of the three-piece foldable silicone lens contains an unpolymerised silicone matrix polymer that becomes polymerised upon exposure to ultraviolet light, he noted. After implanting the lens, irradiating specific areas of the lens with a digital light delivery device induces the polymerisation of the unpolymerised silicone, causing a local shrinkage of the lens material. In this way it allows post-implantation correction up to plus or minus 2.0 D of sphere and up to -2.0 D of astigmatism, and multiple adjustments are possible, he explained.

In a series of eight patients, Dr Hengerer and his associates implanted the LAL in the non-dominant eye leaving the other eye emmetropic – whether prior to surgery or following implantation of an IOL – with a visual acuity of 20/20 or better. The primary adjustment targeted a spherical refraction of 0.25 D to -0.50 D and a cylindrical refraction less than 0.75 D. The secondary adjustment aimed at inducing an asphericity of -0.20 (Z12) with a 4.0mm pupil. Two lock-in treatments completed the adjustment process.

At a follow-up of six months after the final adjustment, the mean uncorrected near visual acuity was J3 compared to pre-adjustment value of J5. In addition, pre-adjustment to post-adjustment, mean UIVA improved from J4 to J1 postadjustment and mean UDVA improved from J3 pre-adjustment to J2. There was a shift in measured asphericity at one month following the aspheric adjustment. Dr Hengerer noted that the first two patients reported a reduction in their distance visual acuity following the aspheric adjustment because of a slight myopic shift postoperatively, but this was corrected by an additional myopic adjustment. In the following patients they aimed for a slight hyperopic outcome.

Dr Hengerer and his associates performed a bilateral aspheric adjustment in a patient whose left eye was dominant. The patient achieved an uncorrected near visual acuity of J2, an uncorrected intermediate visual acuity of J2 and intermediate visual acuity of J1 and a distance visual acuity of 20/32 in his non-dominant right eye and achieved respective values of J2, J2 and 20/25 in his dominant left eye.

Treatment can improve near and intermediate visual acuity, and distance visual acuity remains stable regardless of the pupil size. Bilateral aspheric treatment is optional but further investigations are necessary to individualise the amount of induced asphericity according to the patient’s needs, he said.

Fritz H Hengerer: fritz.hengerer@kgu.de