[Morphological evaluation of posterior capsule opacification in diffractive multifocal intraocular lenses]

Diffractive multifocals belong to the first generation of multifocal intraocular lenses. Dure to their optical principle of diffraction multifocals separate the incoming light on two foci (41%) with 18% loss of scattered light. Therefore, reduced contrast sensitivity and glare have been frequently described with this lens.

We evaluated 42 eyes of 25 patients (age at surgery 63.8 +/- 8.8 years) 3 years after implantation of a Pharmacia 811E diffractive multifocal (MIOL). They were tested for functional results including contrast and glare (Mesoptometer II). In addition 22 eyes were evaluated for posterior capsule opacification (PCO) using digitalized retroilluminations photographs and the EPCP image analysis program.

Average visual acuity was 0.77 +/- 0.20 (uncorrected distance), 0.93 +/- 0.21 (corrected distance), 0.94 +/- 0.13 uncorrected near) und 0.98 +/- 0.08 (best corrected near). PCO-values quantified by EPCO were 1.13 +/- 0.59 (Range 0.07 to 2.1). On average 18.1 +/- 14.9% of the optic area showed an opacification grade 1, 35.8 +/- 26.6% grade 2 and 7.7 +/- 17.1% grade 3. Contrast sensitivity showed no patient with contrast level 7 or better for monocular evaluation, but 30% for binocular testing. Only 4% met the criteria for night driving when tested for glare. Spearman correlation did not reveal any significant correlation between PCO-values and visual acuity, contrast sensitivity or glare (all p > 0.24, all r < 0.22).

Patients with diffractive multifocal IOLs showed excellent results for near and distance visual acuity three years after implantation. However, contrast and glare results were poor, probably due to a rather high PCO-rate. Future developments of the lens type should include PCO-reducing factors, such as sharp edge optics and foldable materials.