EyeWorld India March 2019 Issue

12 EWAP FEATURE March 2019 Preference for LRIs, femto AKs or toric IOLs Dr. Baartman said his choice among LRIs, AKs, and toric IOLs depends on the preoperative characteristics of each patient. “In general, I tend to favor femtosecond laser arcuate keratotomy incisions for patients with 0.5 D to 1.25 D of regular corneal astigmatism, especially if there is no significant contribution of the posterior corneal or lens and it shows up in the patient’s refraction,” Dr. Baartman said. For patients with greater than 1.0 D to 1.25 D of corneal cylinder, this is when Dr. Baartman starts thinking about toric lenses. “Other patient characteristics I consider are presence of epithelial basement membrane dystrophy or significant ocular surface dryness, and if I’m considering incisional refractive surgery, I always evaluate the posterior corneal curvature to make sure we’re not looking at astigmatism developing from early or otherwise occult corneal ectasia,” he said. The orientation of the preoperative corneal cylinder is also something he considers, and he tends to be more conservative in treating with-the-rule astigmatism compared to against-the-rule. Dr. Greenwood will base his decision on whether to choose an LRI, femto AK, or toric IOL on how much astigmatism is measured on the LENSTAR. If it is less than 0.50 D, he does not correct the astigmatism. If it is between 0.5 and 1.25 D, he uses AKs with the femtosecond laser, and if it is greater than 1.25 D, he will use a toric IOL. “I use the Barrett toric calculator to aid in preop IOL selection, but I confirm it in the OR using aberrometry,” he said. “I use the Hill-RBF for non- toric IOL selection.” Dr. Yeu said that she will always choose a toric if she can, particularly for anyone with more than 0.7 D of against-the-rule or with-the-rule of more than 1.25/1.3 D. “I always go for femto AKs for a primary case,” Dr. Yeu said, adding that she uses the femtosecond laser at the time of surgery as it helps create a standardized capsulotomy and provides a more predictable refractive outcome. Accuracy of LRIs and femto AKs Dr. Greenwood said that he finds femto AKs more accurate in that they are more precise. “Manual techniques are good, but we will never be as precise as the laser, whether it is AKs or capsulotomies,” he said. “Of course, it all depends on how accurate your preop measurements are and how you are marking where to place your incisions.” Dr. Greenwood said that if your marks are not accurate, the placement of the incisions may not be at the axis you initially intended. “This is especially important as the eye can cyclorotate when laying supine.” Prior to placing the IOL, Dr. Greenwood uses intraoperative aberrometry to help select the IOL power and measure the total corneal astigmatism. “If I did AKs and there is still some residual astigmatism, I can open them to get a greater effect,” he said. “If I chose a toric IOL, I will use the measurements to guide the toric power selection.” Dr. Baartman said that he likes the accuracy of the femtosecond laser for placing astigmatic incisions at precisely the right position, depth, length, and centration. “On the femtosecond platform, OCT imaging allows me to be very specific in my intended depth of 90%, and I can feel confident in its safety,” he said. “I also appreciate the ability to open or not open the incisions, and I often make that decision with the use of intraoperative aberrometry.” Advantages of toric IOLs Dr. Baartman thinks toric lenses have the advantage of being able to treat larger amounts of refractive astigmatism without making large incisions on the cornea. “This can come into play when treating patients with ocular surface disease or a history of keratorefractive surgery, when incisional refractive surgery may not be best for the patient,” he said. “Particularly in those patients with larger amounts of cylinder, you have the ability to rotate a toric lens or employ an excimer laser to touch up residual astigmatism.” Ultimately, Dr. Baartman said that this helps preserve more of the corneal tissue and natural strength compared to strictly using an incision or keratoablative refractive surgery. The biggest advantage is that they can correct higher amounts (greater than 1.5 D) of astigmatism compared to AKs or LRIs, Dr. This 68-year-old female wants a higher quality of uncorrected distance vision with cataract surgery of the left eye. The LENSTAR and Placido disc topography show good alignment in the quantitative values, with about 1 D of anterior corneal astigmatism around 165 degrees. The posterior cornea on the Cassini LED topographer demonstrates a small amount of with-the-rule astigmatism, which ultimately leads to a total corneal astigmatism that is slightly more than 1 D. Source: Elizabeth Yeu, MD Continued on page 14 Correcting corneal – from page 11