EyeWorld Chinese June 2021 Issue

O n Thursday May 20, 2021, APACRS hosted a webinar with four key lead- ers in refractive cataract surgery: Dr. Tetsuro Oshika (Japan), Dr. Graham Barrett (Australia), Dr. Ronald Yeoh (Singapore), and Dr. Hungwon Tchah (South Ko- rea). Presentations were given by each of these key leaders followed by discussion. As to- ric intraoperative lenses (IOLs) become more technologically advanced, cataract surgeons can tend to their patients’ greatest needs by incorporat- ing toric IOLs into their prac- tice to provide them with the best outcomes. Tips to Optimize Outcomes of Toric IOLs Dr. Tetsuro Oshika from the Uni- versity of Tsukuba in Japan pro- vided tips on optimizing patient outcomes of toric IOLs. Tip #1: Distinguish, before sur- gery, between regular astigma- tism and irregular astigmatism. It is extremely important to do so when considering toric IOLs because only regular astigmatism can be corrected with toric IOLs. To do so, Dr. Oshika recom- It's aToricWorld Optimizing Cataract Surgery Outcomes with Toric IOL mends viewing a Fourier map which decomposes topography into 4 different components: spherical, regular astigmatism, asymmetry, and higher-order irregularity. The asymmetry and higher-order irregularity topog- raphies are characterized as irregular astigmatism and cannot be corrected with toric lenses. Tip #2: The K value as mea- sured by keratometry is not equal to total corneal astigmatism. The K value is estimated based on the anterior corneal surface measurement alone, and the posterior corneal surface is not considered. Looking at just the anterior cornea surface, younger eyes tend to exhibit with-the- rule astigmatism and changes to against-the-rule astigmatism in older eyes. However, the posterior cornea surface ex- hibits primarily against-the-rule astigmatism (ATR) in eyes of all ages; there is no shifting pattern towards with-the-rule (WTR) astigmatism. Therefore, it is very important to use proper toric calculators, such as the Barrett formula, to avoid undercorrecting for ATR astigmgatism or overcor- recting for WTR astigmatism. Tip #3: Precise axis marking is important. Typically, the surgeon places a reference mark on the patient’s eye before surgery and the axis mark during surgery. In- correct marking can be a source of error in toric lens placement. Incorrect markings may show vertical deviation as a result of the upper eyelid covering the cornea. Incorrect markings may also be seen as laterally deviated or asymmetrically placed. Mark- ings can be made either manually or digitally using devices such as VERION™, CALLISTO eye ® , or the ORA System™. In one small comparative study Dr. Oshika conducted, eyes were either manually or digitally marked, and the results showed no significant difference in postoperative axis misalignment between the two methods. Thus, digital marking is useful due to simplicity, although manual marking still provides accurate marking. Tip #4: Use the latest model of toric IOLs. Recent advances in technology have allowed for modified haptics. In the new J&J Vision TECNIS ® Toric II IOL, the frosted haptic offers more surface texture and increased friction within the capsule. In another study conducted by Dr. Oshika, axis misalignment was compared between the TECNIS ® Toric IOL, which maintains the standard polished haptics, and the TECNIS ® Toric II IOL. The results showed that the amount of axis misalignment was sig- nificantly reduced in the Toric II IOL compared to the Toric IOL, this clearly indicates that the rotational stability is very much improved with the TECNIS Toric II IOL. Dr. Oshika also compared the unfolding speed of the Toric IOL to the Toric II IOL and found that the Toric II IOL exhibited a significantly shorter time for initial haptic movement, complete separation of the haptic from the optic, and unfolding of the lens to 11mm. With the TECNIS ® Toric II IOL providing faster release of the haptics as well as increased friction with the capsule, rota- tional stability is improved. From the discussion, Dr. Oshika ex- plained that the unfolding speed is faster for the Toric II IOL than the old Toric IOL because the the frosted haptic does not stick to the optic while in the cartridge during insertion. Tip #5: Anterior capsule cov- erage is very important for the rotational stability of the toric lens. When comparing complete coverage of the continuous curvilinear capsulorhexis (CCC) edge to partial coverage, Dr. Oshika found that the amount of axis misalignment at 6 months post-operative was statistically significant with complete CCC edge coverage exhibiting lower axis misalignment than partial coverage. Secure fixation of the lens in the capsular bag contrib- utes to greater rotational stability. Tip #6: When necessary, perform repositioning surgery at one week or later postoper- atively. What’s important is the timing of repositioning surgery and the final outcome. A study conducted by Dr. Oshika found that if repositioning surgery is performed immediately after cataract surgery, there is a sig- nificantly higher degree of final misalignment and, in fact, some IOLs rotated subsequently after repositioning surgery to the same direction. Contrastingly, waiting for 7 days or longer after cataract surgery significantly decreased the degree of final misalignment of the IOL. Furthermore, Dr. Os- 's Compared to other toric IOLs on the market, the TECNIS ® Toric II IOL performs significantly better than the AcrySof ® Toric IQ IOL and similarly to the HOYA Toric IOL in terms of axis misalignment at 1 month postoperative.