Toric trifocal IOLs
Toric trifocal intraocular lenses (IOLs) provide lasting emmetropia and good near vision in many patients
Well-centred trifocal IOL two months after surgery. Image courtesy of Matteo Piovella MD.
Toric trifocal intraocular lenses (IOLs) provide lasting emmetropia and good near vision in many patients at the three-year follow-up mark, according to Matteo Piovella MD, Centro di Microchirurgia Ambulatoriale, Milan, Italy.
For Dr Piovella, the successful implantation of one toric trifocal IOL involves a very personal story. In 2014, a Zeiss AT LISA toric trifocal IOL was implanted in his own left eye. The results were excellent, and Dr Piovella has continued to practice. “And I still get asked to perform live surgery!” he said.
Dr Piovella provided an overview of toric trifocals, with a particular focus on the Zeiss AT LISA toric trifocal IOL. “We currently have 12 years of experience with multifocal IOLs, starting with the ReZoom and TECNIS mix and match from AMO. Trifocal IOLs have now replaced bifocal IOLs in most countries where they are available. Extended-depth-of-focus (EDOF) IOLs are another new development but they are less effective for near vision,” he said.
However, most multifocal bifocal IOLs have several weak points, he noted. These include a lack of intermediate distance vision and a reduction of contrast sensitivity of up to 25%. Furthermore, near vision is penalised with dim lighting conditions, particularly with diffractive IOLs.
The AT LISA is a trifocal IOL with an asymmetrical light distribution. This IOL distributes 50% of the light to far, 20% to intermediate, and 30% to near.
Dr Piovella’s team conducted a study in which they implanted the AT LISA trifocal toric in 82 astigmatic eyes of 50 patients, with a mean preoperative corneal astigmatism of 1.46D. Within this group, 84% of eyes were within 0.50D spherical equivalent postoperatively. “Only 9% of patients sometimes have to use glasses,” said Dr Piovella.
He outlined the indications for a smooth transition to presbyopic IOLs. He advised not using these lenses in high myopic or high hyperopic patients or after radial keratotomy. Patient eyes selection and examination are crucial, and healthy preoperative convergence, stereopsis and near vision are all important, he emphasised.
“And remember, a multifocal toric optic is more sensitive to cylinder misalignment than a monofocal toric optic. Astigmatism axis alignment needs digital technology like the CALLISTO system. Also remember that all diffractive IOLs penalise near vision in dim lighting conditions due to a reduction of contrast sensitivity and depth of focus,” he noted.
This should not be seen as an insurmountable problem, as it can be solved by increasing the ambient light, for example by using a smartphone’s flashlight (torch) function.
“Patients like getting this advice, and they will thank you for having provided them with a simple and efficient solution,” said Dr Piovella.
Matteo Piovella: email@example.com
Dr Piovella is a consultant for Abbott Medical Optics, TearScience and Carl Zeiss Meditec