Conventional cataract surgery procedure often produces excellent uncorrected distance visual acuity, but near vision typically is blurred, requiring patients to wear reading glasses. In monovision cataract surgery, the surgeon intentionally makes one eye mildly nearsighted, which often enables the patient to see acceptably well up close without “readers.”

Monovision cataract surgery: Study design

The study evaluated 26 patients who had successful full-correction cataract surgery in one eye and agreed to have cataract surgery performed on the second eye that would leave that eye moderately nearsighted for a monovision correction.

The target refractive endpoint for the second eye was -1.00 to -1.50 diopters (D) of myopia.

Data gathered pre-operatively and three to four months after surgery included visual acuity, contrast sensitivity and stereopsis. The patients also were questioned to determine their overall satisfaction and their degree of spectacle independence.

Monovision cataract surgery: Study results

Findings of the study determined three to four months after cataract surgery on the second eye included:

• The mean refractive difference between the two eyes (the amount of myopia in the “near eye” when the first eye had a perfect distance correction) was -1.16 D.
• 92 percent of patients achieved uncorrected distance visual acuity of 20/30 or better.
• 92 percent of patients attained uncorrected near vision of 20/32 or better.
• All patients maintained good stereopsis (depth perception) and contrast sensitivity.

When questioned about how happy they were with the results, cataracts patients were generally satisfied with their vision after monovision cataract surgery.

One fourth of patients had no need for prescription eyeglasses; one patient required glasses full-time. The remaining patients needed glasses only for specific tasks, such as reading.

No patients required IOL exchange or other additional refractive surgery, such as PRK, Epi LASIK eye surgery or LASEK eye surgery.

Conclusion

The researchers concluded that monovision cataract surgery of the type performed in the study produces good visual outcomes and patient satisfaction without troublesome visual symptoms sometimes associated with multifocal IOLs.

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

According to a new study conducted by researchers at Stanford University, large pupil size is not correlated with an increase in visual disturbances after wavefront-guided LASIK.

Pupil size and LASIK: Study design and methods

The relationship between pupil size and quality of vision after LASIK is a controversial one, with some studies suggesting large pupils increase the risk of visual disturbances after LASIK and other studies failing to find such a correlation.

To further investigate this issue, researchers at Stanford’s Department of Ophthalmology evaluated 51 patients who underwent bilateral wavefront-guided LASIK for the treatment of low to moderate myopia.

Patients were classified in one of three groups based on their pupil size in medium-light conditions: small pupils (less than 5.5 mm), medium pupils (5.5 to 6.0 mm) and large pupils (greater than 6 mm).

Before and after surgery, patients were asked to complete a questionnaire regarding problems with glare, haze, halos, blur and other nighttime vision disturbances. After surgery, questionnaire responses were obtained at 1 week, and 1, 3, 6 and 12 months post-operatively.

Results and conclusions

Annie Chan, MD, an ophthalmology resident at the university, reported the results of the study at the recent annual meeting of the American Society of Cataract and Refractive Surgery (ASCRS).

One month after surgery, no statistically significant differences were found between groups with regard to visual symptoms.

One year after surgery, however, the researchers were surprised to find that subjects with small pupils experienced more glare at night than those with medium-sized and large pupils.

No significant differences were found among the three groups for the other criteria measured at this final visit.

“In all groups, glare at night had worsened at one month after surgery compared with baseline, but then it improved progressively with time,” Dr. Chan said. “By the last visit, glare symptoms at night were reduced compared with baseline in eyes with medium and large pupils.”

SOURCE:  Large preoperative pupil size does not predict visual symptoms postLASIK. Ophthalmology Times. Meeting E-News. Published online April 4, 2009.

The study is investigating the effect of a new fifth-generation femtosecond laser, the iFS laser (Abbott Medical Optics, Santa Ana, Calif.) on LASIK outcomes for naval aviators. When combined with AMO’s CustomVue wavefront-guided LASIK, the new iFS laser is part of the company’s all-laser custom LASIK procedure called iLASIK.

According to AMO, the advanced features of the new laser include:

• Faster speed
• Lower energy (less likely to cause inflammatory tissue response)
• Creates a smoother corneal bed under the flap (for better visual results and easier flap lifting)
• Ability to create an inverted, bevel-in side cut (for greater flap stability after surgery)
• Ability to customize the angle of the side cut (to maximize flap stability)

iLASIK: Study design

David J. Tanzer, MD, director of the U.S. Navy Refractive Surgery Program, recently described the preliminary results of a study of 32 eyes of naval aviators treated with the the iLASIK procedure. Prior to surgery, all 32 eyes were nearsighted, ranging from -0.86 to -4.58 diopters (D) of myopia, with mean of -2.00 D.

Dr. Tanzer and colleagues compared the results of these iLASIK treatments with the results of 135 nearsighted eyes treated with all-laser LASIK where the corneal flap was created with AMO’s previous generation FS 60 kHz femtosecond laser. The range of myopia in this second group of eyes was -0.54 to -6.94 D prior to surgery, with a mean of -2.41 D.

Results and conclusions

Analysis of the study data revealed:

• One day after surgery, 97 percent of eyes in the iFS group achieved 20/20 or better UCVA, compared to 82 percent of eyes in the FS 60 kHz femtosecond laser group.
• One week after surgery, 100 percent of eyes in the iFS group achieved 20/20 or better UCVA, compared to 97 percent of eyes in the FS 60 kHz femtosecond laser group.
• One week after surgery, 19 percent of eyes in the iFS group achieved 20/10 UCVA (twice as good as 20/20), compared to eight percent of eyes in the FS 60 kHz femtosecond laser group.

Dr. Tanzer noted that in addition to providing better visual outcomes, the other benefits of the new iFS femtosecond laser — specifically the surgeon’s ability to adjust the side cut angle of the flap and create an elliptical flap — are highly valued for LASIK performed on military personnel. These advances help create a more stable flap and retain a stronger corneal structure after surgery when compared with previous methods of flap creation.

SOURCE:  Bringing LASIK to the next level. EyeWorld. May 2009. (Supplement: Premium Clinical Options for Cataract and Refractive Surgery, sponsored by Abbott Medical Optics.)