EyeWorld India December 2021 Issue

REFRACTIVE EWAP DECEMBER 2021 21 initially recommend that as an alternative to glasses and contacts,” Dr. Waring said. “However, as patients move through various stages of lens dysfunction, in the context of their refractive errors and/or desires, then we would look at surgical interventions.” Surgical options Shamik Bafna, MD, said he tends to break down the treatment options for presbyopia by what is accessible in the U.S. and what’s available outside the U.S. “In the U.S., there are modalities that you can employ within the cornea and modalities to employ within the lens,” he said. Within the cornea, Dr. Bafna said the most common option is monovision. PRK, LASIK, or SMILE can be used where you take the non-dominant eye and under correct a little to give near vision and correct the dominant eye for distance vision, he explained. Most patients like monovision quite a bit, but the main drawback is it’s not a long-term solution. “You’re dealing with presbyopia, which continues to progress,” Dr. Bafna said. “Someone may be able to read initially, [but] they may lose near vision over time and have more intermediate vision when the presbyopia gets worse.” Monovision works well for patients in their 40–50s. For those in their late 50s–60s, monovision doesn’t work as well, he said. In the past, many people would defocus the near eye, Dr. Bafna said, to a target of –2 to –2.5 D. Over time, they realized that creates too much anisometropia, and patients don’t like losing that much distance vision in the near eye. They lose more depth of field and depth of focus because the eyes aren’t working together. These days, he said patients prefer –1.25 to –1.5 D, so there’s less difference between the two eyes. This is better tolerated by patients and there’s not as much loss of distance vision. With monovision there is some compromise associated; you have to give up distance vision to get near vision and vice versa. “When we target monovision, we try to simulate it with a contact lens trial to make sure a patient likes it,” Dr. Bafna said. While monovision is one of the most popular options within the U.S. for presbyopia correction, another strategy Dr. Bafna’s practice employs is an inlay, specifically the Kamra (AcuFocus). He explained how Kamra increases the depth of field using small aperture optics. “You don’t sacrifice as much distance vision in the near eye as when you do traditional monovision.” However, there is not a lot of market demand for the inlay, he said. Another inlay is the Flexivue Microlens (Presbia), which completed an FDA trial and is being analyzed. Dr. Bafna was involved in this clinical trial. He also mentioned allografts, which use actual corneal tissue instead of a foreign body. These options are still in development or not yet available in the U.S. An inlay from Allotex, which is undergoing FDA trial for near vision, is placed superficially in the cornea with the idea that you want to change the curvature of the non-dominant eye to allow it to focus near. This option is made from human tissue that has been cryopreserved. Soosan Jacob, MD, has introduced a similar idea. Her technique is called the presbyopic allogenic refractive lenticule (PEARL), which uses leftover corneal lenticular tissue removed in a SMILE procedure. There is a process to make sure there are no issues with the tissue; a small button is taken out and cryopreserved to use in another patient’s eye, Dr. Bafna explained. From a corneal perspective, Dr. Waring mentioned the blended vision approach with LASIK and/or PRK and with implantable contact lenses. He also said that there are new scleral treatments in development. He serves as the director of the Scientific Advisory Board for the new Laser Scleral Microporation procedure (LSM, Ace Vision Group), which he said is showing promise in early human trials. This is a minimally invasive presbyopia surgical procedure designed to naturally restore function. There are several other surgical procedure options available outside the U.S., Dr. Bafna said, mentioning presbyLASIK, PRESBYOND (Carl Zeiss Meditec), and INTRACOR used internationally. PresbyLASIK creates a multifocal cornea, Dr. Bafna said. “It’s an attempt to replace the dynamic process of accommodation with static modification of the corneal surface,” he explained, noting that this is primarily for patients who are low hyperopes. It’s not used that frequently, he said, due to the loss of contrast sensitivity it creates and reduction in distance vision. With INTRACOR, instead of