How to achieve the perfect multifocal IOL implantation

Good multifocal IOL (MFIOL) candidates are highly motivated to be spectacle independent and tend to have an easy going and adaptable personality. They have healthy eyes and a low degree of astigmatism. Hyperopic presbyopes tend to make the best candidates.

Poor MFIOL candidates tend to have hypercritical personalities, do a significant amount of night driving, or use computers for prolonged periods. Low myopes tend to get the poorest results.

These were the conclusions of Dr A. Keith Bates, Consultant Ophthalmic Surgeon with the Taunton and Somerset Hospital in England, during his presentation on MFIOL patient selection.

Dr Bates noted that ophthalmologists typically maintain one of two positions on MFIOLs; either they feel MFIOLs have greatly enhanced their practice and they use them regularly, or they blame MFIOLs for many unhappy patients and no longer use them.

Surgeons with experience of laser vision correction tend to incorporate MFIOLs into their practice more easily, Dr Bates said, because the key to both procedures is thorough and careful patient selection and an understanding of patient motivation.

Doctors who wish to incorporate MFIOLs successfully into their practice must select patients carefully, adopt a team approach and thoroughly educate the patient. They must establish realistic expectations. Accurate biometry and astigmatism control is vital, as is meticulous surgery and a stepwise introduction of the IOLs into the practice.

"One should be wary of any patient who has more than ten questions, any female patient who has more than three cats, any male patient who plays golf more than three times per week or any patient who has more than three pairs of glasses for different activities, since these tend to make poor candidates" he told gathered delegates on a humorous note.

Doctors can help to identify the best and worst candidates through questionnaires and discussion. Find out a patient's occupation, hobbies and other regular activities. Establish their tolerance to haloes, their desired reading distance and, of course, their pupil size.

Dr Bates then provided thumbnail portraits of the major MFIOL devices on the market in his experience and explained the importance of selecting the correct MFIOL for each patient.

The ReZoom MFIOL (AMO) is a refractive, distance-dominant lens and works best when the pupil size is greater than 2.5 mm. Haloes are often commented upon, he said, and it offers better intermediate vision at the expense of near vision. "It is most useful for golfers, computer users and in mix and match," he said.

The ReSTOR MFIOL (Alcon) is a refractive/diffractive lens with 50:50 distance to near light ratio, with apodized rings oriented centrally only. Initially near vision is maximal at 14 to 18 inches and small print requires good light, intermediate vision is less good than distance or near. "It may take six months to achieve functional computer vision and patients need to be warned of this", Dr Bates noted. The device functions well with small pupils but those with large pupils under normal lighting conditions may have more difficulty with near and intermediate vision", he said.

The Tecnis MFIOL (AMO) is a full optic diffractive lens offering 50:50 light distribution for distance and near vision. Haloes are less of an issue than with refractive IOLs and it offers better reading in low light conditions. "It is a good option in patients with large pupils", Dr Bates said.

Finally, the Acri.LISA Bifocal MFIOL (Carl Zeiss Meditec) is another diffractive/refractive lens, which is MICS compatible and has a 65:35 distance to near light ratio. "It may give better distance contrast sensitivity," Dr Bates explained, and it adds +3.75 D for reading so reading distance is slightly increased.

Dr Bates finally offered some MFIOL pearls. He said doctors should always "under promise and over deliver" and tell all patients they will need spectacles for some visual tasks. Expect spectacle independence 85% of the time NOT 85% of patients totally spectacle independent. Remember that excellent distance vision is more critical than excellent near vision. Patient selection is crucial and whilst questionnaires and other devices may help in this regard, there is no substitute for quality chair time.

"Initially target only the most suitable patients and implant the same IOL bilaterally", he said. "Experience allows for aligning the nuances of IOLs now available to patients' requirements and allows the possibility of mixing of IOLs."