All About Cataracts

Bilateral cataract surgery intentionally designed for monovision produces good visual acuity and high patient satisfaction, according to a study published in the Journal of Cataract and Refractive Surgery. 

Researchers in Australia evaluated the outcomes of cataract surgery performed on both eyes of 26 patients. In all cases, a monovision correction was performed with intraocular lenses (IOLs). The target refractive endpoint of the second eye corrected for near vision was mild to moderate myopia ranging from -1.00 D to -1.50 D. 

Visual acuity, contrast sensitivity, stereopsis, and patient satisfaction were measured prior to surgery and 3 to 4 months post-operatively. Patients were also asked how frequently they needed eyeglasses after surgery.

Monovision is a method of vision correction where one eye is fully corrected for distance vision and the other eye is made (or is left) nearsighted so a person with presbyopia can see acceptably well up close without reading glasses. Monovision can be performed with contact lenses or refractive surgery, including refractive cataract surgery.)

Results of the study included:

1. 96 percent of the patients achieved uncorrected binocular distance visual acuity of at least 20/30.
2. 92 percent achieved approximately 20/30 or better uncorrected near visual acuity. 
3. Good depth perception and contrast sensitivity were maintained after surgery. 

Patients were generally satisfied with their vision after surgery. Approximately 25 percent of patients did not need glasses for any reason; one patient was totally dependent on spectacles. No patient required an IOL exchange or other additional refractive surgery.

The authors of the study concluded monovision cataract surgery achieves good visual function and patient satisfaction without the risk of troublesome visual symptoms sometimes associated with multifocal IOLs used in cataract surgery to correct presbyopia.

Source: Patient satisfaction and visual function after pseudophakic monovision. Journal of Cataract and Refractive Surgery. June 2009.  

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.

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.

The U.S. Food and Drug Administration (FDA) recently approved a new astigmatism-correcting intraocular lens (IOL) for use in cataract surgery. The new lens, called the AcrySof IQ Toric IOL, is manufactured by Alcon and is now available for use by cataract surgeons in the United States.

In addition to having a toric design to correct astigmatism, the new premium IOL also has aspheric curves to reduce a common post-surgical optical error called spherical aberration. By reducing spherical aberration, the AcrySof IQ Toric IOL is designed to improve image quality and contrast sensitivity for better night driving vision and sharper vision overall.

In a clinical trial required by the FDA prior to approval, among 37 patients who had the IOL implanted bilaterally for the treatment of cataracts and astigmatism, 98 percent did not need prescription eyeglasses for distance vision six months after surgery. Also, the lens continued to show good rotational stability when checked one year after surgery. 

According to Alcon, the AcrySof IQ Toric IOL is a good choice for any patient undergoing cataract surgery who has 0.75 diopter (D) or more corneal astigmatism prior to surgery. The IOL corrects up to 2.50 D of astigmatism, and it can be combined with a procedure called limbal relaxing incisions to correct even higher amounts of astigmatism.

Like other premium IOLs, the AcrySof IQ Toric IOL costs more than a conventional monofocal intraocular lens and will increase your cataract surgery cost. For details, consult a cataract surgeon near you.