Eyeworld

EW CATARACT 35 December 2017 Despite being more painful during the recovery, PRK provides the same refractive outcome as LASIK and with little chance for had 1.00 D of residual cylinder. But with that manifest correction, she achieved 20/20 vision." Dr. Miller moved on to the left eye, which obtained 20/25 vision without correction, with which the patient was happy. "Now the question is, how do you tune up a refractive error of –1.50 +1.00 axis 175 in someone who has a more-or-less on-axis toric lens implant?" Dr. Miller said. Options considered The patient's small spherical equiva- lent refractive error of –1.00 D raised several possible approaches. Rotating the lens might have improved her cylinder slightly, but would not have resolved the spheri- cal equivalent refractive error. Exchanging the lens for a 1.00 D spherical refractive error raised concerns for Dr. Miller because if the capsular bag contracted in a slightly different manner, it may have left the lens sitting in a slightly differ- ent anteroposterior location, which would undermine the calculation. "In doing a lens exchange, you also run the risk of capsule tear, in which case you can't even use a toric lens," Dr. Miller said. "Also, the in- cision may not heal the same way as during the first surgery, so you have incision issues potentially affecting the astigmatism outcome." Lesser concerns with lens ex- change include the risk of infection and retinal detachment. "For large errors, like 3.00 D or 4.00 D, there is no question that you would swap out the lens, but when you are dealing with one increment up or down in power, you have to question whether a lens exchange is the way to go," Dr. Miller said. Another limitation is the 0.50 D increments in lens spherical powers available for toric implant models. "You don't have a lot of finesse when you're changing lens implant power," Dr. Miller said. Another way to reduce spherical error is with LASIK. "But in a 73-year-old, LASIK is not a great idea in my opinion because there is a very real chance of ending up with a dry eye situation," Dr. Miller said. "I don't generally like to do LASIK beyond age 55 because patients who are older typically have more dry eye issues than younger patients." Preferred approach Dr. Miller decided the way to maxi- mize precision and reduce the odds of complications was with PRK. continued on page 36

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