EyeWorld Asia-Pacific September 2019 Issue

S HANGHAI, China, April 2018—Having laid the foundation for modern optics at its inception, ZEISS (Jena, Germany) continues today to be a pioneer in the manufacturing of optical sys- tems. Laying yet another milestone in its more than 170-year history, the company organized its most re- cent cataract and refractive surgery user meetings in combination—an acknowledgement of the blurring of the lines between the formerly distinct fields of anterior segment ophthalmic surgery. This intersection between cataract and refractive surgery can be fraught with challenges, with refractive procedures potentially complicating later cataract surgery and cataract surgery potentially negating the benefits of earlier refractive procedures ZEISS offers elegant solutions. In a rapid-fire session and video symposium, experts offered pearls for ensuring the best outcomes for patients, beginning with optimiza- tion of the ocular environment and the procedure itself. Meanwhile, the company leads the way with its new range of extended-depth of-focus (EDOF) IOLs, the AT LARA family of IOLs, which offer an even wider range of focus with excellent optical performance and quality of vision with fewer side effects. More- over, the high degree of precision offered by ZEISS’s refractive lasers and premium procedures such as small incision lenticule extraction (SMILE) leaves eyes better suited to the implantation of sensitive premium IOLs such as multifocals. Finally, ZEISS offers technologies such as the CIRCLE software that rounds out the company’s cataract and refractive surgery solutions. Optimizing cataract and refractive surgery Tear film optimization Conditions need to be optimized even before cataract and refractive surgery can begin to ensure the best possible outcomes, and one of the most obvious targets for this is the tear film. If the tear film is not optimized, said Michael Lawless, MD , Sydney, Australia, “it leads to trouble with accuracy, with less than ideal results, and unhappy patients, and you’re not making the best of what surgery can offer.” In particular, a non-optimized tear film will prevent patients from enjoying the full value out of high-quality lenses such as torics and procedures such as SMILE. In addition, he said, a better tear meniscus results in better recovery of corneal sensation after LASIK, almost certainly after SMILE as well. Improved recovery leads to “a cascading set of good things.” But how do you get through the conflicting, confusing maze of what to do? For his study, Dr. Lawless went right to the center of the confusing maze of ocular surface disease and picked out tear osmolarity. Look- ing at 1,150 consecutive refractive and cataract surgery consultations, patients who came in for vision cor- rection over the 1-year period from October 2016 to October 2017, Dr. Lawless determined that tear osmo- larity was the first test they un- derwent with trained technicians, before any drops were administered. The test was conducted in a con- trolled environment with known temperature and humidity. Subjectively, 37% of patients Shaping Tomorrow’s Vision: Supplement to EyeWorld Asia-Pacific September 2019 APACRS felt their eyes were dry, with 21.8% using a lubricant. The mean tear os- molarity was 300.24±11.57 mOsm/L (range 217 to 368 mOsm/L) with a median of 299 mOsm/L, describing a bell curve. Following a standard cut-off value of >308 mOsm/L, 80.2% were normal, 19.8% hyperos- molar, but with a 316 mOsm/L cut- off, 92.5% were normal and only 7.5% were hyperosmolar. They also found a mean inter-eye difference of 8.7±8.3 (0 to 66), with a median of 6. Inter-eye difference in relation to osmolarity did not describe a bell curve—the higher the tear osmolar- ity, the bigger the inter-eye differ- ence. They considered an inter-eye difference of 8 abnormal. At their clinic, Dr. Lawless has standardized their approach begin- ning with tear osmolarity tests and the Ocular Surface Disease Index pa- tient questionnaire in every patient to identify those with a tear film osmolarity of >308 mOsm/L and an inter-eye difference of 8 who will require treatment. Patients undergo a slitlamp examination and have their tear film optimized prior to IOL master biometry if for cataract surgery and prior to SMILE if for corneal laser surgery. Preoperatively, they optimize the tear film with artificial tears, topical corticosteroids, oral fish oil, and lid scrubs. Dr. Lawless noted that this is not to cure dry eye, but only to optimize the film for better surgery results. This protocol has improved the quality of their preop biometry, reducing suboptimal results from 40% to 5%. Dr. Lawless said that it has made preop assessment efficient and repeatable and ensures that patients are optimally prepared for both corneal laser and cataract sur- gery. Furthermore, issues are iden- tified preop so there are no postop surprises, and no “difficult conver- sations” to be had with the patient a month after surgery. Finally, this process of tear optimization ensures patients are engaged in achieving better results for themselves. Personalizing A-constants The postop outcome has a close re- lationship with IOL calculation, and the A-constant plays a very import- ant role in those calculations, said Jiang Yaqin, MD, China. Dr. Jiang said that while many doctors think that the manufactur- er-provided A-constant is sufficient, subjective factors can affect the value, including surgeon habits, incision type and quality, suture material, IOL design and structure, patient factors such as axial length, and choice of IOL formula. In her experience, 90% of patients who were unhappy with their postop results had a residual refractive error, which in turn re- sulted from a non-optimized A-con- stant. Optimizing their A-constant according to postop refractive error, effective lens position, and the defo- cus curve of the particular IOL used gave Dr. Jiang’s clinic an accuracy rate of 95%. Currently, Dr. Jiang is actively optimizing A-constants for more IOLs, collecting a larger sample, and discussing the use of A-constants with different doctors. Surgeons at the clinic are looking into opti- mizing A-constants according to corneal curvature. Dr. Jiang said that continuous A-constant optimization is import- ant and necessary to achieve the best results after refractive cataract surgery. The news magazine of the Asia-Pacific Association of Cataract & Refractive Surgeons Copyright 2019 APACRS. All rights reserved. The views expressed here do not necessarily reflect those of the editor, editorial board, or publisher, and in no way imply endorsement by EyeWorld, Asia-Pacific or APACRS. “ If the tear film is not optimized, it leads to trouble with accuracy, with less than ideal results, and unhappy patients, and you’re not making the best of what surgery can offer. ” Michael Lawless, MD, Sydney, Australia,