EyeWorld India December 2017 Issue

by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer Toric IOLs: When do we enhance? Guidelines to help manage postop outcomes and meet patients’ expectations T he goal of any ophthal- mic surgery is to provide the best possible vision. Carefully calculated tar- get refraction is easily thrown off by residual refractive error, leav- ing some patients less than satis- fied. High patient satisfaction was strongly correlated with residual astigmatism, according to the outcomes of a survey discussed at the 2017 ASCRS•ASOA Symposi- um & Congress that included 117 patients who received either mul- tifocal or accommodating IOLs. 1 With many of today’s patients demanding spectacle-free vision, surgeons need to understand their options and pool their resources to best reduce residual error. Expectation of no glasses “According to a survey we con- ducted, 34% of our patients feared needing glasses or having blurry vision,” said John Hovane- sian, MD , Harvard Eye Associ- ates, Laguna Hills, California, in a presentation he gave at the 2017 ASCRS•ASOA Symposium & Congress. “These results came from a typical cataract patient population. People know from their friends that cataract surgery is safe, but what they are look- ing for is excellent vision. That’s what leads to patient satisfaction: excellent vision. This is what we are in the business of. When our patients are happy, we have done our job. We achieve this through reducing refractive error.” Dr. Hovanesian’s survey showed that 56% of cataract patients were extremely satisfied with their postoperative visual outcomes with residual cylin- der <0.75 D, while 80% reported being extremely satisfied with a postoperative cylinder <0.75 D (P<0.02). “A patient’s satisfaction increases with decreasing astig- matic error, and although studies have shown patient satisfaction with <0.75 D residual astigma- tism, I think the cutoff point is 0.5 D. Likewise, when patients can function entirely without glasses, they are very satisfied. Our poll showed 81% ‘very satis- fied’ without glasses, while only 63% were ‘very satisfied’ when they needed glasses for any activ- ity (P<0.01). That is a hard one to deliver—no glasses ever. But it is what is expected of surgery and therefore important that we try to achieve this with every tool we have,” he said. He explained that with toric IOLs, a 1-degree lens rotation resulted in a 3.3% decrease in the toric effect, making a 10-degree rotation with a corresponding 33% decrease in toric effect unac- ceptable. A 30-degree rotation meant a complete loss of toric effect, and more than 30-degree IOL rotation was equal to induc- ing new astigmatism. The same was true for misalignments, with even 5 degrees of misalignment responsible for tilting and distort- ing the visual image beyond any acceptable limit. Potential causes of postopera- tive residual astigmatism include: the wrong location (poor axis, IOL rotated, or poor IOL place- ment), the wrong lens choice (poor power measurement, sur- prising surgically induced astig- matism and/or posterior cylinder), or compounding factors (most commonly ocular surface disease). Ocular surface disease seems to be recognized more and more as a factor affecting cataract surgical outcomes using toric IOLs. “Ocular surface disease is the elephant in the room. The incidence of dry eye among our cataract patients is 80%. Most of our patients have ocular surface disease, and it can affect the out- comes of surgery,” Dr. Hovanesian said. Enhancement indications When the sum of the spherical and cylindrical error is >0.5 D, Dr. Hovanesian considers perform- ing enhancement. If the cylinder falls outside of the 0.5 D range, patient satisfaction is likely to suf- fer. According to Dr. Hovanesian, the best way to manage refractive error depends on the type of er- ror you are dealing with. Smaller spherical errors are best cor- rected with the use of a piggyback lens, PRK, or LASIK, while larger spherical errors might be best handled with a lens exchange. Cylindrical error can be fixed by lens rotation, but not for larger er- rors, which require either PRK or lens exchange. He recommended the website astigmatismfix.com, a toric results analyzer, as an extremely useful tool for backup, in the manage- ment of post-surgical residual error. The website helps cataract and refractive surgeons to deter- mine if a previously placed toric IOL is ideally aligned. It compares the current location of the toric IOL to the patient’s current mani- fest refraction, and can assess if rotating the IOL would decrease “ When our patients are happy, we have done our job. We achieve this through reducing refractive error. ” - John Hovanesian, MD EWAP CATARACT/IOL December 2017 57 continued on page 58