EyeWorld Asia-Pacific June 2017 Issue

20 EWAP FEATURE June 2017 their dominance 10 times you might get a different reading six of the times. I think it is important to emphasize the dominant eye for distance but realize that there are exceptions. This is another example of why there is not a cookbook recipe for how this is done. Refractive surgery cannot put people into a certain bucket. It is much more complex and requires significant time and energy to determine the best solution for each patient.” One-eye procedure Satisfying a presbyopic patient with a one-eye procedure can be extremely challenging. Presbyopia is a problem of the crystalline lens, which Dr. Kugler thinks would ideally best be solved at its source— the lens. However, for people in stage 1 DLS, or individuals in their early to mid-40s, replacement lenses offer a suboptimal substitute for the natural, crystalline lens in good working condition, leaving surgeons reluctant to remove it. This is where treating a lens-based problem from within the cornea with corneal inlays or monovision becomes an interesting alternative. Dr. Kugler explained, “It is a challenge to fix a presbyope with a one-eye procedure, largely because we are not fixing the problem at its source. However, we do know from decades of monovision that monovision is a very well tolerated solution, whether it is created by LASIK or by an IOL, provided that it is done appropriately. I think that in 2017 our definition of near vision is very different from what our definition of near vision was 20 or 30 years ago. People are using computers, cell phones, and tablets at a different distance than they once needed to see the things they were looking at up close. Even occupational activities have moved to more of an intermediate range than they once were.” According to Dr. Kugler, intermediate vision is more important today than true near vision. This benefits monovision and benefits corneal inlay patients because patients with corneal inlays can achieve good vision in the intermediate range. Monovision tends to be more challenging when near vision is too strongly targeted, resulting in too large a difference between the near and distance eyes. Dr. Kugler noted that the visual cortex of most patients responded poorly to the large gap between near and far targets. “Monovision with an intermediate target is very successful, and corneal inlays are excellent for the intermediate range with less compromise of distance than standard monovision. Therefore, I think that although it still remains a challenge to satisfy a lens-based problem with a cornea-based solution, the combination of an inlay with a slight near target tends to be a very good solution,” Dr. Kugler said. Previous surgery Patients who have had previous refractive surgery are an ever-growing demographic. For decades, the average age of LASIK patients has been 38 years, which now, some 20 years on, places these individuals in the midst of presbyopic eye changes. According to Dr. Kugler, “There is a tsunami of patients out there who had their distance vision corrected when they were younger and who now desire a near vision correction. With corneal inlays, we have an avenue to reach out to these patients who are now reaching DLS and offer them a solution. The KAMRA inlay [AcuFocus, Irvine, California] lends itself well to post-LASIK patients, assuming they have enough corneal stroma remaining.” Dr. Thompson indicated that in post-PRK or LASIK patients, it all comes down to corneal thickness. “One thing we know about corneal inlays is that we need a healthy bridge of tissue over the inlay. The other issue is their lenticular status, which is why I like measuring the optical scatter index to ensure a clean optical system, meaning the cornea, lens, vitreous, and tear film are not affecting their image quality. If I diagnose that they have reduced image quality from early lens changes, then an inlay, PRK, or LASIK monovision is not in their best interests, and their best option is to either do nothing and wait for lens replacement or do an early lens replacement. With the high standards achieved with modern day multifocals, it is important to offer patients that option and understand lenticular status before advising them to proceed with a corneal correction of presbyopia,” Dr. Thompson said. He spoke about the sustainability of corneal inlay monovision as compared to LASIK or PRK monovision as being an attractive feature for patients and an incentive for inlay correction. “In my research, I found that the effect of the inlay helping near vision did not wear off nearly as quickly as with PRK or LASIK monovision. The idea of this long-lasting effect getting them through their 50s and 60s is very attractive to presbyopic patients. If they are developing any evidence of haze or they are not satisfied by 4 to 6 months postoperatively, I would typically recommend removal of the inlay. If they are healing well, their best corrected image quality is good, but their residual refractive error is affecting their visual joy, then we talk about laser enhancement,” Dr. Thompson said. EWAP Editors’ note: Drs. Kugler and Thompson have financial interests with AcuFocus. Contact information Kugler: lkugler@kuglervision.com Thompson: vance.thompson@vancethompsonvision.com Choosing – from page 19