Surgeon offers advice on how to select patients for multifocal IOLs

Subjective outcome criteria and the potential for plano refraction are the two main priorities that should be considered.

SIENA, Italy – In selecting candidates for multifocal IOLs, surgeons must be accurate in evaluating objective and subjective outcome criteria. They should also be aware that there is an element of unpredictability in the complex interaction of physiological, psychological and neuronal factors that determine the success of these implants.

“The message goes from the eye to the brain, but we cannot explore the route that it takes. Neuroadaptation is an uncontrollable process,” Francesco Carones, MD, said at the meeting of the Italian Society of Cataract and Refractive Surgery.

This might explain why with this type of implant, “results are not always consequential to our expectations,” he said.

Potential for plano refraction

Experience shows that an accurate patient selection with detailed counseling can greatly reduce the number of unexpected failures with multifocal IOLs.

“The time you normally spend for the routine preoperative examination of your cataract patient is prolonged by the investigation of a wide number of aspects that must be clear when you decide whether or not to implant a multifocal lens,” Dr. Carones said.

Surgeons should focus on refraction for this procedure.

“The potential for plano refraction is a condition for good results with multifocal IOLs. If this condition is satisfied, the patient can be spectacle-free for both near and distance vision and have a fairly good intermediate vision. A slight compromise concerning visual quality has to be accepted, but the side effects of multifocality are negligible in most cases,” he said.

If plano is not achieved, even the smallest residual refractive error can decrease distance vision, he noted. A –0.5 D residual error can reduce visual acuity from 20/20 to 20/32. Near acuity also is affected, and the patient is forced to reduce the distance from the reading target. In addition, the quality of vision decreases, and patients are likely to experience visual disturbances, particularly at night.

The potential for plano refraction is based on a number of selection criteria. Patients with asymmetric, irregular or high astigmatism and patients with corneal aberrations should be excluded. Transparency should be evaluated through the entire optical system, from the cornea to the macula.

“Vitreous irregularities are a contraindication, and in case of secondary opacification, Nd:YAG laser capsulotomy must be performed immediately,” Dr. Carones said.

Patients also must have a healthy, functional macula to compensate for the reduction in the quantity of light that reaches the retina through multifocal IOLs.

“A macula that is not entirely functional would lead to a great reduction in visual quality and visual performance,” Dr. Carones said.

In case of intraoperative complications such as capsular bag rupture or zonular damage, the decision to implant a multifocal lens should be reconsidered because decentration cannot be tolerated with these implants.

Binocularity is another important aspect. Although some patients are happy with monolateral implants, the best performance and the elimination of visual disturbances are normally obtained when the second eye is also implanted.

“When evaluating patients, take into account amblyopia and lazy eyes,” Dr. Carones said.

Causes of failure of multifocal IOLs Amount of time that should be spent on patient selection Source: Carones F

Subjective outcome criteria

Most surgeons would agree that subjective outcome criteria, and therefore all the aspects related to the patient’s expectations, habits, desires and personality, are often the key to the success of this surgery.

“They represent a good 45% in the prognostic factors for successful outcome and are the cause of 90% of the failures,” Dr. Carones said.

Motivation is the first aspect to be considered.

“The ideal patient is strongly motivated to see without glasses, is a dynamic person with an active lifestyle and has an optimistic attitude but with reasonable expectations for the outcome,” Dr. Carones said.

Usually, these patients are willing to accept a possible compromise in terms of visual quality and are able to adapt to the glare and halos they might experience after implantation.

Nevertheless, the potential drawbacks of the implant must be clearly explained to all patients, and in no case should the surgeon promise that they are going to eliminate spectacles completely. Reduced spectacle use is a more realistic target, he said.

Expectations are generally proportional to the patient’s preoperative vision. Cataract patients and older patients tend to have more realistic expectations and be happier with the results than refractive lens exchange patients and younger patients.

Hyperopic patients are the most strongly motivated to reduce spectacle dependence, Dr. Carones said.

Occupation, hobbies and day-to-day activities must be carefully considered in relation to visual requirements. Patients should be asked how often they drive and how much of their driving is done in night light conditions. As far as computer use is concerned, a different evaluation should be made for laptop and desktop personal computers.

“Perfectionistic, demanding and hypercritical patients should immediately be excluded, and caution should be used with patients who have too many concerns about possible side effects. The choice of a multifocal lens should never be forced on anyone,” Dr. Carones said.

Patients who have adapted to monovision are also poor candidates, and so are those who are fully satisfied with multifocal glasses.

“It may seem contradictory, but intraocular multifocality is a different matter, requires a new adaptation and often turns out to be disappointing at intermediate distances,” he noted.

After all this, the unpredictability of neural processing can still modify even the most accurately predicted outcome. In Dr. Carones’ experience, however, this happens only in a minority of cases.

For more information:

• Francesco Carones, MD, can be reached at Carones Ophthalmology Center, Via Pietro Mascagni 20, 20122 Milan, Italy; +39-02-76318174; fax +39-02-76318506; e-mail: fcarones@carones.com. He is a paid consultant for Alcon Labs.

• Michela Cimberle is an OSN Correspondent based in Treviso, Italy, who covers all aspects of ophthalmology. She focuses geographically on Europe.