Trifocal lens technology improves intermediate vision

September 1, 2014

A diffractive trifocal IOL is novel technology that delivers good near, intermediate, and far vision and has other advantages.

 

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A diffractive trifocal IOL is novel technology that delivers good near, intermediate, and far vision and has other advantages.

 

By Cheryl Guttman Krader; Reviewed by Matteo Piovella, MD

Monza, Italy-Outcomes in patients with a diffractive trifocal IOL (AT LISA tri 839MP and 939MP, Carl Zeiss Meditec) implanted show that the unique optic design provides a full range of good uncorrected vision, said Matteo Piovella, MD.

“Diffractive multifocal IOLs are generally bifocal lenses that distribute light rays to foci for distance and near and so patients implanted with these IOLs have poor vision at intermediate distances,” said Dr. Piovella, medical director, Centro Microchirurgia Ambulatoriale, Monza, Italy. “In contrast, the trifocal technology improves intermediate vision without compromising vision for near or far.”

The trifocal technology is also less pupil size dependent, provides better quality of vision by reducing light loss, and minimizes the risk for bothersome night vision symptoms relative to diffractive multifocal IOLs, he added.

“The trifocal IOL has fewer rings on the optic surface, which reduces the potential for visual disturbances that can be difficult to manage in demanding patients. In addition, it is independent of pupil diameter up to 4.5 mm,” Dr. Piovella said. “Therefore, it provides good quality vision in younger patients who tend to have a larger scotopic pupil.”

“In my opinion, the trifocal technology IOLs will soon become the market leader, surpassing the current top-selling multifocal IOLs,” he added.

 

Refractive outcomes

Dr. Piovella presented outcomes from 55 eyes of 33 patients with the aspheric trifocal IOL (model 839MP) implanted and from 25 eyes of 16 patients who received the toric version (model 939MP).

“Accurate refractive outcomes are critical for achieving optimal results with any multifocal technology and astigmatic correction is important for any patient with more than 0.75 D of astigmatism,” he said.

Preoperatively, the trifocal group had a mean best-corrected visual acuity (BCVA) of 0.76, mean distance uncorrected visual acuity (UCVA) of 0.3, and mean SE of 0.52 D.

After a mean follow-up of 2 years, mean distance UCVA was 0.90, mean BCVA was 1.00, and mean SE was 0.11 D. In monocular testing, mean near UCVA was 20/25, 100% of patients were seeing 20/40 or better in monocular testing of intermediate UCVA and more than 90% were 20/25 or better.

Preoperatively, eyes with the toric trifocal IOL implanted had a mean BCVA of 0.80, mean SE of 0.89 D, and mean corneal astigmatism of 1.37 D. After 1 year of follow-up, mean distance UCVA was 0.99, mean BCVA was 1.00, and mean SE was –0.25 D.

The lens is made of a hydrophilic acrylic material with a hydrophobic surface. It has a single-piece design and can be inserted through incisions ≥1.8 mm using the BLUEMIXS 180 injector/cartridge set (Carl Zeiss Meditec).

 

The trifocal IOL optic distributes 50% of light for far, 20% for intermediate and 30% for near. At the IOL plane it provides a near add of +3.33 D for good reading vision at a comfortable distance and an intermediate add of +1.66 D.

Diffractive bifocal IOLs work best for minimizing patient complaints when a multifocal IOL is implanted, Dr. Piovella noted. However, with all the diffractive technology IOLs, there is loss of contrast sensitivity up to 30%.

“To overcome this issue, the patient is informed about the need for extra light power when reading in mesopic conditions or print with similar tone colors,” he said.

 

Matteo Piovella, MD

E: piovella@piovella.com

Dr. Piovella is a consultant to Abbott Medical Optics, Aaren Scientific, and Carl Zeiss Meditec.