Eyeworld

64 | EYEWORLD | SPRING 2024 ATARACT C Contact Cummings: abc@wellingtoneyeclinic.com Durrie: ddurrie@iorpartners.com Kopstein: akopstein@myk2vision.com Relevant disclosures Cummings: Alcon Durrie: 2EyeVision Kopstein: None Dr. Cummings tests suppression with the Worth four dot test. Furthermore, he said once the decision is made on the dominant eye, a stereo target is put up on the chart and stereop- sis is assessed. Correct both eyes to emmetropia and assess stereopsis. "In my experience, 95% of patients will have good distance stereopsis," Dr. Cummings said. "Now start defocusing the eye assigned to reading. Ask the patient to contin- ually assess the stereo target and to note when distance stereo is lost. Defocus to –0.25, –0.50, and –0.75. Almost everyone still enjoys stere- opsis for distance vision at this level. Once the defocus is –1.00 in the reading eye, some will start losing their stereo vision. For these, their reading target should not exceed –0.75 D. Some can maintain stereo vision up to –1.50 and lose it at –1.75 D. Their reading eye target should not exceed –1.50. A small part of the population can maintain stereo vision at –1.75 and even –2.00 D and have the freedom to select their target." Dr. Cummings added that with mono/ blended vision being set with laser vision correc- tion or ICL surgery, there is likely still some re- sidual accommodation, and these patients might receive a slightly less myopic reading target. With a monofocal IOL, he said some may target –1.0 but still require readers or target –2.0 and then need assistance at intermediate vision. With advanced technology IOLs like EDOF, target emmetropia in the distance eye and –0.75 to –1 in the reading eye for a complete to near complete range of vision, he said. If a patient is seeking a full range of vision but needs to drive at night, Dr. Cummings said dominance again plays a key role in creating a "custom match." This approach starts with a diffractive trifocal IOL in the non-dominant eye. Prior to the second eye surgery, glare and halo tolerance is assessed. If it's not bothersome, the patient can choose a trifocal for their dominant eye as well; however, if the patient is bothered with the glare and halo in the non-dominant eye, they receive a non-diffractive EDOF IOL in the dominant eye.. "With this combination, they have an excel- lent range of vision and can still drive at night thanks to there being no glare and halos in the dominant eye [with a non-diffractive EDOF]," Dr. Cummings said. Distance and near preferred vision and the LAL Dr. Kopstein, whose sole private practice is performing refractive lens exchange (RLE), said assessing distance and near preferred eyes is important with the Light Adjustable Lens (LAL, RxSight). "It's an important technology. … It's power- ful because it can be adjusted, and it's equally powerful because of the quality of the optics and the EDOF that you get from the LAL," Dr. Kopstein said, noting that the original LAL has allowed his practice to get 92% of people com- pletely out of glasses; he thinks this number will rise to 95% with the LAL+. When it comes to distance and near pre- ferred eyes, Dr. Kopstein said his practice has learned that in about 20% of patients, the domi- nant eye is not their distance preferred eye. "I am one of those people. If you put me in contact lenses that fully correct me for distance and you hold a +1 lens over my right eye and a +1 lens over my left eye, I will tolerate the blurring on my right eye more than I will on my non-dominant left eye. About 20% of patients are like this, so it's important to do dominance testing but also to verify that the dominant eye is indeed the distance preferred eye," he said. "If you end up adjusting the LAL in the non-dominant eye for reading and that's actu- ally the eye the patient prefers for distance, you will likely have an unhappy patient." Dr. Kopstein said the conversation with LAL patients about its EDOF qualities after the light delivery device adjustment calls into question for some patients why you wouldn't just use monofocal lenses to achieve monovision/blend- ed vision effects. "We have been gathering data to answer the question: What are the distance character- istics of the near-preferred eye after bilateral LAL lock-in?" he said. "The range of refraction for the near preferred eye with the LAL is plano to –1.75 in our first thousand bilateral 'lock-ins' (average –0.75). … For these near-preferred eyes, the distance vision range is 20/20 to 20/80 (median 20/30). This is very different from 'standard IOL' monovision, where the pa- tient closing their distance eye rarely has useful distance vision in the near-preferred eye. This appears to be a unique feature of the LAL com- pared to the standard monofocal IOL." continued from page 63

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