Contrast sensitivity and depth of focus with aspheric multifocal versus conventional monofocal intraocular lens

Laboratoires Domilens, Lyon, France, has introduced a new aspheric multifocal intraocular lens (IOL), the Progress 3. The central portion, measuring 4.7 mm in diameter, has an anterior surface of progressively increasing power, such that there is a central add of +5.00 dioptres. We compared contrast sensitivity and depth of focus in patients who received the Progress 3 and in those who received a conventional monofocal IOL.

Prospective study. Forty patients with age-related cataract were randomly divided into two groups: 20 patients received the Progress 3 aspheric multifocal IOL, and 20 patients received a conventional monofocal IOL of similar design. Contrast sensitivity was measured with the Pelli-Robson letter-based chart. Depth of focus was determined by dialling a series of overcorrections over the patient's manifest refraction until the patient read 6/12 clearly. The depth of focus was defined as the range over which 6/12 or better acuity was achieved. Quality of vision was evaluated by patient questionnaire.

Mean contrast sensitivity was significantly lower in the patients with a multifocal IOL than in those with a monofocal IOL (1.38 vs. 1.56 log units) (p < 0.001). The mean depth of focus values for the two groups were 3.10 D and 1.65 D respectively (p < 0.001). The prevalence of subjective problems was similar in the two groups.

In our opinion, aspheric multifocal IOLs should be reserved for patients who are willing to trade increased depth of focus for reduced contrast sensitivity postoperatively.