All About Cataracts

Having multifocal intraocular lenses (IOLs) implanted in both eyes for the treatment of cataracts produces better visual outcomes than a single multifocal IOL implanted in one eye, according to a study published in the June 2009 issue of Journal of Cataract & Refractive Surgery.

In the study, an AcrySof ReSTOR multifocal IOL was implanted 1) in one eye of patients with a natural (non-cataractous) lens in the other eye; 2) in one eye of patients who had a conventional monofocal IOL implanted in the other eye; and 3) in both eyes of patients with a cataract in one or both eyes.

Visual acuity, contrast sensitivity and stereopsis (depth perception) of all eyes was measured six months after cataract surgery. Patients also were surveyed about the quality of their vision and their overall satisfaction.

Patients receiving bilateral multifocal IOLs had the highest satisfaction score (92 percent), and 77 percent of these patients achieved spectacle independence after surgery.

Among patients with the multifocal IOL implanted in one eye only, 75 percent reported being satisfied with their vision, and spectacle independence was achieved by 56 percent of patients with a natural lens in their other eye and 65 percent of those who had a monofocal IOL implanted in their other eye.

Patients with bilateral multifocal IOLs also had better uncorrected near visual acuity, stereopsis, best-corrected near vision and best-corrected intermediate vision.

More patients with bilateral multifocal IOLs (77 percent) experienced halos at night compared with patients who received a multifocal IOL in one eye only (57 percent), but in most cases halos were minot and did not significantly affect patients’ overall satisfaction with their visual outcome.

A silicone aspheric intraocular lens (IOL) reduces spherical aberration and enhances contrast sensitivity in low light compared with a conventional spherical IOL, according to a study published in the June 2009 issue of American Journal of Ophthalmology.

Sixty-two eyes of 31 patients who underwent bilateral cataract surgery were evaluated. Patients received a Tecnis Z9000 silicone aspheric IOL in one eye and a CeeOn 911A silicone spherical IOL in the other eye. Both intraocular lenses are made by Abbott Medical Optics (AMO). Follow-up exams were performed at 1, 3, 6 and 12 months after surgery.

Though both the aspheric and spherical IOLs provided essentially the same uncorrected and best-corrected visual acuity in bright and medium-light conditions, the eyes with the aspheric IOLs had fewer higher-order aberrations (specifically, spherical aberration) and exhibited better contrast sensitivity in low-light conditions, the study authors said.

Improved contrast sensitivity in such conditions suggests the Tecnis Z9000 aspheric IOLs may provide sharper vision than conventional spherical IOLs for activities such as driving at night.

Silicone aspheric IOLs generally are considered to be premium intraocular lenses. As such, your cataract surgery cost typically will be higher if you choose these lenses, and the cost of the lenses may not be fully covered by Medicare and other types of vision insurance.

German researchers have found that visual performance — specifically reading speed — with multifocal intraocular lenses after cataract surgery improves with time, suggesting the brain adapts to multifocal IOLs as time goes by.

“When analyzing multifocal lens performance, it is important to follow patients over time and to remember that there is a brain behind the eyes,” said Manfred R. Tetz, MD, of the University of Berlin at the 2009 annual meeting of the American Society of Cataract and Refractive Surgery held recently in San Francisco.

Dr. Tetz and colleagues evaluated the visual performance of 25 patients who had one of two brands of multifocal IOLs (Tecnis Multifocal IOL, Abbott Medical Optics; AcrySof ReSTOR, Alcon Laboratories) implanted bilaterally after cataract removal. All patients were examined for a period of six to 18 months after surgery.

Both multifocal IOLs provided good uncorrected visual acuity (UCVA) at all distances. Mean UCVA at intermediate (arm’s length) was approximately 20/40 for both groups. 

When evaluating reading speed as a measure of visual performance, the researchers found that the patients were capable of significantly faster reading speeds than patients who received bilateral multifocal IOL implants and were followed for only three months.

“This indicates there is a neural adaptation by the patient over time,” said Dr. Tetz.

Although reading speed for both groups slowed with smaller font sizes, patients in the AcrySof ReSTOR multifocal IOL group could read small fonts faster than those in the Tecnis Multifocal IOL group.

Source:  Faster reading speeds over time indicates brain adapts to multifocal IOLs. Ophthalmology Times. Meeting E-News, April 4, 2009.

Multifocal intraocular lenses (IOLs) provide comparable distance and intermediate visual acuity to that provided by conventional monofocal IOLs and provide the additional benefit of significantly better near vision without reading glasses, according to a new study published in Japanese Journal of Ophthalmology.

The researchers compared visual outcomes for 81 patients who underwent bilateral cataract surgery: 34 patients received non-tinted multifocal IOLs (Alcon ReSTOR), 30 patients received yellow-tinted multifocal IOLs (Alcon ReSTOR Natural) and 17 patients received conventional non-tinted monofocal IOLs.

Results of the study included: 

• All three types of IOLs provided comparable uncorrected visual acuity for distant and intermediate (arm’s length) viewing.
• There was no significant difference in the distance visual acuity results for the yellow and non-tinted multifocal IOLs.
• Both multifocal IOLs provided significantly better uncorrected visual acuity for near viewing, compared to the monofocal IOL.

The study also found that pupil diameter influenced the near visual acuity results of eyes receiving the ReSTOR multifocal IOLs. Patients with larger pupils had better near vision with the multifocal lenses than patients with small pupils.

Source:  All-distance visual acuity in eyes with a nontinted or a yellow-tinted diffractive multifocal intraocular lens. Japanese Journal of Ophthalmology. March 2009.