Interlenticular opacification associated with IOL type

"Theoretical studies have indicated that there may be an advantage to dual-optic accommodating IOLs over mono-optic IOLs in that greater amplitude of accommodation would be obtained with relatively less anterior translation of the anterior optic of the IOL. Therefore, dual-optic accommodating IOLs have been developed, and very good results have been obtained recently in rabbit eyes with these lenses, compared with silicone plate IOLs, in preventing anterior and posterior capsular opacification," Dr. Werner said.

Interlenticular opacification, however, is a concern when implanting a dual-optic system in the bag, she noted. Dr. Werner is a research assistant professor at John A. Moran Eye Center, Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City.

The investigators used 10 sets of dual-optic accommodating IOLs (Synchrony, Visiogen), 10 control pairs of silicone-plate lenses, and 10 control pairs of single-piece hydrophobic acrylic lenses. The IOLs were implanted in the bag in 15 New Zealand rabbit eyes after phacoemulsification. Three bilateral IOL combinations were done in five rabbits for each combination, by the same surgeon. The capsulorrhexis measured between 4.5 and 5.0 mm in diameter. The incision was enlarged to facilitate implantation of the IOLs. The dual-optic IOL was inserted folded, the silicone-plate lenses were inserted unfolded, and the hydrophobic acrylic lenses were injected, Dr. Werner recounted.

The animals were followed for 6 weeks, during which time they were examined by slit lamp. At the 6-week time point, the eyes were enucleated and fixated; the different forms of capsular bag opacification were analyzed from a posterior view of the anterior segment and histologic studies were performed.

The interlenticular opacification was scored on a scale of 1 to 4.

"We noted the area according to the number of quadrants involved and the intensity or extent of the opacification according to the position of the material in relation to the center of the interlenticular space. This was graded as 1 if the material was in the periphery, it was graded as 2 if the material was in the paracentral area, and it was graded as 3 if the material was protruding at the center of the interlenticular space," Dr. Werner said (Figure 1).

She reported that interlenticular opacification was significantly (p = 0.002) associated with pairs of hydrophobic acrylic IOLs. The silicone-plate lenses were associated with a moderate amount of interlenticular opacification. A relative lack of interlenticular opacification was seen with the silicone lens.

"The silicone lens was associated with significantly less central posterior capsular opacification and significantly less extension of interlenticular opacification or extension multiplied by quadrants. However, Soemmering's ring formation did not differ among the three lenses," she stated.