A combination of a refractive and a diffractive multifocal IOL for correction of presbyopia virtually eliminates complaints about intermediate vision that are frequent among patients who undergo bilateral implantation of diffractive lenses.
This synergistic effect results in very high rates of spectacle independence and, consequently, in very high levels of patient satisfaction, added Dr. Bucci, who practices in Wilkes-Barre, PA.
In a presentation, he discussed his experiences with multifocal IOLs, beginning with bilateral implantation of an apodized diffractive lens (AcrySof ReSTOR, Alcon Laboratories) in June 2005. He later began using a combination of that lens and a refractive multifocal IOL (ReZoom, Advanced Medical Optics). The refractive lens is implanted in the dominant eye, and the diffractive IOL is implanted in the nondominant eye.
"Unfortunately, they had very poor intermediate function, and 17 of 55 gave serious, spontaneous, voluntary complaints regarding their intermediate vision," Dr. Bucci said. Further, more than one-third (38%) of the patients undergoing lensectomy in this cohort complained about their intermediate vision. Looking for a way to alleviate these problems, he began testing a combination of multifocal IOLs, implanting the aforementioned lenses in 145 patients in a second cohort.
At the time of his presentation, Dr. Bucci had complete data on 110 patients. The mean follow-up overall was 8 months.
Results show that, in the first cohort, in the patients who received the diffractive IOL in both eyes, the mean near vision was J 1.00. In the second cohort, with the combination of lenses, the near vision was J 1.07. The difference was not statistically significant. Unilateral and bilateral near vision was measured at the patient's best focal distance.
Although near vision was similar in the two patient groups, a large, statistically and clinically significant difference was observed in intermediate vision. Mean intermediate vision was J 3.81 in the first cohort, compared with J 2.39 in the second cohort (p = 0.0001). The mean follow-up was 13 months for the first cohort and 8 months for the second cohort.
Dr. Bucci also reported that intermediate vision was no more than J4 in 71% of the patients who received the diffractive implant in both eyes (39/55) but in only 21% (23/110) of the patients who received both the diffractive and the refractive lenses.
Analyzing complaints by procedure and age, 13 of 17 who complained were patients who had undergone lensectomy, and 11 of these 13 were younger than 60 years old. These findings may help identity a subgroup of patients more likely to be dissatisfied following bilateral implantation of the diffractive IOL, Dr. Bucci said.
"We see that a refractive/diffractive combination outperformed a diffractive/diffractive combination," he added. "Out of the 145 patients in the combination group, even without all the astigmatism fixed, there were no voluntary, spontaneous intermediate complaints of the depth and character observed in the diffractive/diffractive group."
The unique optical characteristics of each multifocal IOL appear to be complementary and produce a synergistic effect. "The weaknesses of each one are covered up by the strengths of the other," Dr. Bucci said. "The [refractive lens] covers the [diffractive lens] in that it has better distance during the day, excellent intermediate, and very good reading in dim light. The [diffractive lens] covers for the [refractive lens] because the reading is better in bright light and there are fewer halos at night."