EyeWorld Asia-Pacific December 2019 Issue

28 EWAP DECEMBER 2019 SECONDARY FEATURE A t the 32nd APACRS annual meeting’s Combined Symposium of Cataract and Refractive Societies (CSCRS)—a symposium APACRS Past President Graham Barrett, MD, has referred to as the society’s “premiere ÃiÃÃ»piÝ«iÀÌÃ vÀ ÌÀii different international cataract and refractive societies came together to provide a concise but comprehensive snapshot of how practitioners from around the world employ “Elegance and Innovation for Perfect Outcomes.” Each of the participating societies was assigned a particular topic for the ÃÞ«ÃÕ\ Ài«ÀiÃiÌ>ÌÛiÃ from the APACRS discussed IOL calculation formulas; from the American Society of Cataract and Refractive Surgery (ASCRS), techniques and technology to achieve precise outcomes; and from the European Society of Cataract and Refractive Surgeons (ESCRS), the management of refractive surprises. Focus on formulas Beginning the discussion on IOL calculation formulas, Chikako Suto, MD, PhD, organized her talk along three iÃ\ £® Ìi «À«ÀÌ>ÌÞ v VÕ>À >>ÌÞ vÀ w`} Ìi ideal reference value; (2) the limitation of the SRK/T formula, highlighting the importance of the optimized A-constant; and (3) the advantages of the Barrett Universal II formula for normal eyes and as well as for unusual and particularly for long eyes. On the proportionality of ocular anatomy, she noted the importance of factoring in symmetry when measuring the >Ý> i}Ì\ >ÃÞiÌÀV>Þ small eyes—that is, those with > ÃÀÌ >Ý> i}ÌLÕÌ > anterior segment within the À> À>}ipÜ>Ûi >Ý> hyperopia; symmetrically small eyes, on the other hand, have nanophthalmia. Dr. Suto said that newer formulas that use additional anterior segment measurements including corneal diameter, anterior chamber depth, and lens thickness are required for improved accuracy in these cases; otherwise, there is a tendency to overlook eyes that have unusual proportionality— having smaller or larger than average anterior segments but >ÛiÀ>}i >Ý> i}Ì° Dr. Suto said that of the intraocular lens (IOL) formulas, the SRK/T is the most widely used in Japan; however, it is not without limitations, especially for iÞiÃ ÜÌ}iÀ >Ý> i}ÌÃ° In these eyes, the formula, when used without adjustment iÌ`Ã ÃÕV>Ã Ìi 7>} V ƂÝ> i}Ì>`ÕÃÌiÌ] ÀiÃÕÌÃ in hyperopic shift. In a comparison between the Barrett Universal II, SRK/T, and Haigis calculators on 276 eyes (using the Tomey OA2000), and a planned acrylic XY1, Dr. Suto said the Barrett Universal II “has Ã}wV>ÌÞ LiÌÌiÀ «ÃÌ«iÀ>ÌÛi results” than the other two in }iÌÌ} iÞiÃ ÜÌ ´ä°x \ with 78% of normal eyes, 84% of unusual eyes, and 93% of long eyes. “The Barrett Universal II was better than the SRK/T in the unusual group, and is useful regardless of the proportionality of ocular anatomy,” she said. Dr. Suto concluded that, in order to improve the accuracy of IOL power calculation, surgeons ÃÕ`\ £® «iÀvÀ >}} Ì determine the proportionality of ocular anatomy; (2) verify the measured values if unusual; and (3) use new generation formulas for unusual eyes. Graham Barrett, MD, noted that predicting cataract surgery outcomes in eyes that have had radial keratotomy or LASIK is “more challenging; it’s as uncertain as rolling a pair of `Vi» LiV>ÕÃi v Ìi y>ÌÌii` cornea the refractive laser procedures create. The resulting eye is aspheric, he said, “but the most important impact of doing laser surgery is we now alter the ratio of the posterior radius to the anterior radius of the cornea.” The normal ratio, he said, is about 82.5%; post LASIK, Ì Ã >LÕÌ Çä¯° i V>Àwi` that “this ratio is what we rely on normally to account for the posterior power of the cornea, and it’s being disrupted by the laser procedure.” This, he said, is why the new generation of machines based on swept-source imaging are so ÌiÀiÃÌ}° º7ÌÃÜi«ÌÃÕÀVi OCT, it’s possible to actually measure now perhaps even more accurately the posterior CSCRS Elegance and Innovation for Perfect Outcomes by Michelle Dalton, ELS, and Chiles Aedam R. Samaniego This article expands on a report that previously appeared in an EyeWorld #UKC 2CEKƂE /GGVKPI 4GRQTVGT RWDNKUJGF FWTKPI VJG PF #2#%45 CPPWCN OGGVKPI JGNF HTQO VQ 1EVQDGT