In a prospective, randomized study, I compared visual outcomes following bilateral implantation of two premium aspheric IOLs, the Tecnis Multifocal (Abbott Medical Optics, Inc., Santa Ana, Calif.) and the Crystalens AO (Bausch & Lomb, Rochester, N.Y.). A total of 40 patients with cataract in both eyes were enrolled with 20 patients (40 eyes) in each group.
To be considered for the study, patients had to have no history of prior ocular surgery, no ocular pathology other than cataract, and no systemic diseases that would increase risk or confound results. All subjects had visual potential of at least 20/25 or better in each eye, naturally dilated pupils of 4.0 mm or greater, and ≤1.0 D of pre-op corneal astigmatism.
Second eye implantation was performed within a week of the first, and all surgeries were performed by a single surgeon. All eyes were targeted for emmetropia, with no intentional mini-monovision.
Patients were followed at 1 day, 1 week, 1 month, 3 months, and 6 months. The interim results reported here include the 1-month follow-up of 35 patients and the 3-month follow-up of 20 patients.
Results Show Great Similarity
The mean age of patients in the study was 69.4 in the Tecnis group and 67.7 in the Crystalens group. There were no statistically significant differences between the groups in age, gender, race, or pre-op spherical equivalent.
At 3 months, both groups had excellent uncorrected distance visual acuity of 0.06 (logMAR scale) or 20/20 (Figure 1). There was also no statistical difference between the groups in intermediate vision, with both groups at 0.03 logMAR or 20/40 uncorrected intermediate acuity at 3 months. This runs counter to the conventional wisdom that a non-diffractive accommodating lens should offer better distance and particularly better intermediate vision than a diffractive multifocal lens. The greater asphericity of the Tecnis lens compared to the Crystalens may contribute to the similarities in distance acuity. Uncorrected near vision was better in the Tecnis Multifocal group.
Patient Satisfaction with Visual Function
Patient expectations of these premium IOLs are very high, but the majority – 88% of the Tecnis group and 78% of the Crystalens group – were satisfied or very satisfied with their overall outcome. There was no drop off in patient satisfaction with night vision, indicating that night-time halos were not a significant problem in either group.
The slightly lower satisfaction in the Crystalens group was likely due to greater difficulty with near vision activities. At 3 months, 89% of those in the Tecnis Multifocal group vs. 55% of those in the Crystalens group reported that reading small print in dim light was easy or very easy. Twice as many of the Tecnis subjects (80% vs. 40%) said their comfortable reading distance was perfect. Twenty percent of Tecnis subjects said the reading distance was a little too close, while 60% of Crystalens subjects said it was too far away. The Crystalens patients were also more likely to report being bothered by fluctuating vision when reading in dim light or working on a computer.
The differences in fluctuating vision are likely due to the inherent design differences of these lenses. The Tecnis Multifocal lens has two focal points, so patients have a very consistent near focal point of 37 cm, making it easy for them to find and utilize their “sweet spot” for near tasks. The Crystalens has a distance focal point, with near vision more dependent on variable accommodative flexing of the optic.
In conclusion, both of these third-generation premium IOLs can work quite well in properly selected patients. Both offer very good distance and intermediate vision. While there are important differences at near, I think it is safe to say that we are getting to the point where the performance of premium IOLs involves far less compromise than it once did, with resulting high levels of satisfaction in our patients.