Case study: Dysphotopsias

Key Points

The subject of the presentation was a 63-year-old woman with significant bilateral cataracts who desired presbyopic correction. After checking for eye dominance, Dr. Henderson operated on the nondominant eye first and implanted a three-piece diffractive multifocal IOL (Tecnis ZM900, Abbott Medical Optics) after uneventful hacoemulsification. Early after surgery, the patient complained of glare and halos, but was otherwise happy.

Her postoperative examination revealed no significant residual refractive error-preoper-atively she had +2.25 D hyperopia with 0.25 D of astigmatism and postoperatively she had no spherical error and was left with the same amount of astigmatism. Evaluation for ocular surface disease showed no corneal problems, lid disease, or tear film abnormalities. Other possible causes for her complaints were ruled out-the IOL was well centered, the patient did not have large pupils, and angle kappa was normal.

"The woman described the glare and halos as noticeable, but she said the photic phenomena were not terrible," Dr. Henderson said. "She wanted to proceed with the same lens in the second eye because she was pretty happy overall with her good vision and especially her good near vision. For many patients, the dysphotopsias improve over time with continued neuroadaptation."

The second eye surgery was performed 4 weeks after the first eye surgery, and on the first day postop, the patient had no significant refractive error, and she was very happy with her uncorrected vision outcome, which was 20/25 for distance and J1 for near. However, beginning at 1 week, she began to complain of glare and halos that were the same in both eyes and present around all lights during the day and at night.

The patient had good fixation, the line of sight appeared to match the pupil center, and she had no evidence of retinal disease. Posterior capsule opacification in the first operated eye was also ruled out.

"It is important to defer opening the posterior capsule if there is any possibility of an IOL exchange," Dr. Henderson said. "Although an IOL exchange is possible after a laser capsu-lotomy, the procedure becomes more difficult and potentially more complicated."

Although large pupils did not appear to be the cause for the photic phenomena, pupillary constriction with brimonidine drops was tried but was unsuccessful in eliminating the halos and glare.

Allow for neuroadaptation

Because the patient was already 3 months postop, the decision of whether to wait longer to see if neuroadaptation would eventually resolve her complaints was getting more complicated. Not only would IOL exchange become more difficult over time, but psychological factors may also have developed that might limit eventual success (i.e., loss of patient confidence may interfere with acceptance of the lens).

Weighing all of these issues, Dr. Henderson and the patient decided to wait for neuroadaptation. The patient was also referred for a second opinion.

"She has decided to keep the multifocal IOLs and not undergo an IOL exchange because although she is still bothered by the dysphotop-sias, she enjoys the excellent uncorrected near vision," Dr. Henderson said.

She noted that using presbyopia-correcting IOLs, whether they are multifocal or accommodating, is challenging.

"All IOLs have certain advantages and disadvantages," Dr. Henderson said. "For multifocal IOLs, preoperative counseling regarding the potential risks of glare, loss of contrast sensitivity, and need for time to adapt to the visual changes is crucial."

If a patient is having difficulty after surgery, the etiology for the visual difficulty should be carefully analyzed and treatment targeted to the specific cause. For example, if the patient is seeing well in the operated eye, both at distance and at near, but is dissatisfied with the speed or ease of reading, usually this patient's vision will improve after implantation of the same multifocal IOL in the other eye.

A patient whose vision is not correctable to 20/25 or better may be affected by loss of contrast sensitivity or need additional time for neuroadaptation.

"In this latter scenario, it may be best not to proceed with the other eye until sufficient time has been given for the patient to adjust to the IOL," Dr. Henderson said. "The time needed for adaptation varies from weeks to several months."

FYI

Bonnie An Henderson, MD
E-mail: bahenderson@eyeboston.com

Dr. Henderson has no financial interest in the subject.