EyeWorld India June 2021 Issue

Supported by tolerance than bifocal IOLs. Dr. Tchah suggests maintaining re- sidual postoperative astigmatism between less than 0.5 to 0.75 D, generally speaking. In the Asian population, about 20-40% of patients with corneal astigmatism exhibit less than or equal to 0.5 D, and no treatment for astigmatism is recommended for these patients. Eight to 10% of the population experience astigmatism between 1.75 to 2.0 D, and this is when patients may benefit from toric IOLs. The majority of the patients, 50- 70%, lie between 0.5 and 1.75 D. For this group of patients, it is not so clear as to whether the patient’s astigmatism should be left untreated or treated using toric IOLs. Astigmatic incision may be more important than any other astigmatism management procedure as it is the most com- monly performed procedure for astigmatic patients undergoing cataract surgery. Limbal relaxing incision, on-axis incision, and astigmatic kera- totomy (AK) are all categorized as astigmatic corneal incisions as they all exhibit the same principles for correcting for astigmatism. In the 1980s, Dr. Tchah published a paper out- lining surgical approaches to mixed and myopic astigmatism. However, the problems Dr. Tchah faced were the lack of precision and reproducibility of the depth and length of the incision. Today, surgeons can perform femto- second laser-assisted cataract surgery with greater precision for capsulotomy, nucleus fragmen- tation, astigmatic keratotomy, and wound incision. In a study by Roberts et al 2 , femtolaser intrastromal AK was shown to offer more efficacious, provided a more accurate correction of corneal astigmatism than limbal relaxing incisions, and can be more reproducible than manual AK. In his practice, Dr. Tchah personally prefers intrastromal femtolaser AK as it may provide a lower chance of infection, inflammation, and perforation as well as less postoperative patient discomfort. However, intrastro- mal AK may be less effective than toric IOLs for higher astig- matic eyes and require a longer arc incision despite being more stable over the long term. Dr. Tchah conducted a study on the 1 year outcome of astigmatic correction after femtosecond la- ser-assisted phacoemulsification. Vector analysis showed a mean correction index of 0.77, meaning 77% of patients’ astigmatism in the study was corrected. Post- operative corneal astigmatism at 1 year, compared with 3 months postoperative, showed better correction with 95% of patients exhibiting less than or equal to 1.0 D and 88% of patients exhib- iting less than or equal to 0.75 D. A German study by Wendelstein et al 3 corroborated Dr. Tchah’s findings showing that 100% of eyes treated with femtosecond laser-assisted corneal arcuate incisions shows less than or equal to 1.0 D and 97% of eyes showed less than or equal to 0.5 D of residual astigmatism. Wortz et al 4 found similar results using the same procedure at 4 weeks after surgery with 100% of patients experiencing less than or equal to 1 D. These studies provide evidence that femto- second laser-assisted AK does indeed provide good results in terms of managing astigmatism in cataract patients. In Dr. Tchah’s routine surgery practice, he performs only femtosecond laser-assisted AK procedures except in cases where patients require toric IOLs and cases with < 0.5 D. Although Dr. Barrett finds keratometry incisions to be unpredictable in terms of the error in predicted astigmatism, Dr. Tchah’s experience has shown that the error is indeed negligible for patients with low to moderate astigmatism. For this reason, Dr. Tchah will turn to toric IOLs when a patient exhibits > 2.0 D. Additionally, Dr. Tchah states that all intra- stromal AK procedures result in less side effects than when performing transepithelial AK. Additionally, Dr. Tchah also uses a manual axis marker due to its ease; when greater accu- racy is required for axis mark- ing, Dr. Tchah will utilize a slit lamp. For automatic axis mark- ing, a good way to compensate for cyclotorsion, new software such as the Catalys ® cOS 6.0 can be used. Finally, Dr. Tchah recommends customizing the nomogram considering each surgeon’s factors for better results as he has found that original nomogram settings may overcorrect astigmatism. From the discussion with the panelists, toric IOLs, especially the new TECNIS ® Toric II IOL, have provided significantly improved patient outcomes. Femtosecond laser-assisted surgery in low to moderate astigmatic cases has shown stable effects over the long term, and the TECNIS ® Toric II IOL has been very successful in patients with high astigma- tism. Using toric IOLs along with toric calculations to target as close to zero astigmatism as possible will highly benefit both the surgeon and patient. References: 1. Lee BS et al. Ophthalmology 2018. 2. Roberts HW et al. J Cataract Refract Surg 2018. 3. Wendelstein JA et al. Acta Ophthalmol 2021. 4. Wortz G et al. Clin Ophthalmol 2020. Optimizing Cataract Surgery Outcomes with Toric IOL Copyright 2021 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. All other trademarks are the intellectual property of their respective owners. © Johnson & Johnson Surgical Vision, Inc. 2021 PP2021CT4836 Astigmatic corneal incisions include limbal relaxing incisions (LRIs), on-axis wounds, and astigmatic keratotomy (AK). Femtolaser intrastromal AK has been shown to be more efficacious than LRIs and wound incisions and are more stable over the long