Eyeworld

77 EW FEATURE October 2015 Complex cataract cases change in effective lens position may have on refractive accuracy," he said. "Manufacturing tolerances in high IOL powers (>30 D) allow for greater variability, which may impact refractive accuracy as well." Dr. Tipperman explained why those with axial myopia are a chal- lenge to measure. "If the biometrist just measures the longest axial length of the eye, they will overes- timate the true 'refractive length' to the actual fovea," he said. "This is one of the advantages of optical biometry where the measurement is obtained by having the patient look at a fixation target and measur- ing the exact distance to the fovea regardless of its location." Although optical biometry is very accurate for measuring high axial myopes, Li Wang, MD, and Doug Koch, MD, demonstrated that the measured axial length biometry should be adjusted for patients with a mea- sured axial length of greater than 25.2 mm when using the Holladay 1 and 2, SRK-T, Haigis, and Hoffer Q formulas, 1 he said. This adjustment does not need to be made with the Barrett formula. At times the IOL power calcu- lations for high myopes will yield a zero or 1 D power lens. "In these cases it is still preferable to place an IOL within the capsular bag since: 1) this decreases the potential for PCO—and because high axial myopes are at risk for RD this is especially beneficial, and 2) in the event the patient does require a YAG capsulotomy, the IOL will act as a physical barrier and prevent vitreous from coming forward into the ante- rior segment," Dr. Tipperman said. Intraoperative surgical considerations Although the majority of cataract surgery is performed under topical anesthesia, it should be noted that if possible it is preferential to avoid retrobulbar or peribulbar anesthesia in patients with high axial myopia because the presence of staphyloma in these patients increases the po- tential for inadvertent globe perfora- tion, Dr. Tipperman said. Intraoperatively, those with short eyes are at risk for developing positive pressure and choroidal effu- sions and hemorrhages. "These can also be seen in the early postoper- ative period along with aqueous mis- direction syndrome," Dr. Tipperman said. "A myopic shift in the early postoperative period may be the first sign that aqueous misdirection is developing." Dr. Devgan offered tips for both short and long eyes. In a tiny eye, using plenty of viscoelastic to deep- en the space is important, he said. "When you break up the cataract, do it within the capsular bag," he added. "Don't try to prolapse the nucleus out of the capsular bag be- cause there's not enough room." For long, myopic eyes you should avoid flattening of the anterior chamber so you don't put pressure or traction on the vitreous base, he said. IOL choices Dr. Allen said that in long eyes, the main consideration is the potential for possible retinal surgical interven- tion in the future and the remote possibility of requiring silicone oil. "Therefore, an acrylic lens is fa- vored," he said. The standard range of most acrylic lenses will accommo- date all but the most extreme long eyes, he added. "For the extreme ax- ial myope, a low power lens or even a minus lens may be required." The Sensar AR40 (Abbott Medical Optics) is available in low and minus powers and is an excellent choice, Dr. Allen said. In short eyes, an acrylic lens with a thin profile, such as the SA/SN60WF (Alcon, Fort Worth, Texas), is Dr. Allen's typical lens of choice. "But its power range is only up to +30 D," he said. The older, non-aspheric SA/SN60AT lens is available in powers up to +40 D, which will accommodate the majori- ty of short axial length eyes, he said. "If a piggyback lens is required, a sil- icone sulcus IOL may be implanted without concern for interlenticular lens opacification." The key, especially in a myopic patient, Dr. Devgan said, is to err on the side of residual myopia when you do lens calculation. For hyper- opic patients, they are usually just happy not to be hyperopic, he said. Changing the IOL power by a little makes a big difference. EW Reference 1. Wang L, et al. Optimizing intraocular lens power calculations in eyes with axial lengths above 25.0 mm. J Cataract Refract Surg. 2011;37:2018–2027. Editors' note: Dr. Allen has financial interests with Bausch + Lomb (Bridge- water, N.J.) and Alcon. Drs. Devgan and Tipperman have no financial interests related to this article. Contact information Allen: q_allen@yahoo.com Devgan: devgan@gmail.com Tipperman: rtipperman@mindspring.com NEW Our Family of Pre-Loaded CTRs Has Expanded Malyugin/Cionni & Henderson Capsular Tension Rings Now Pre-Loaded in Morcher EyeJets Malyugin/Cionni CTR • Eyelet at curved end is sutured to sclera • Unique design facilitates smooth introduction into capsule • The only injectable Cionni type CTR Henderson CTR • Scalloped design facilitates cortical removal • Maintains the desired stretch of the capsular bag Standard CTRs • Stabilize the capsule during surgery • Available in three sizes to accommodate various capsule bags Henderson CTR TYPE 10C Standard CTRs TYPES 14, 14A, 14C Malyugin/Cionni CTR TYPE 10G 800.932.4202 Visit FCI-Ophthalmics.com to watch the EyeJet informational video. For more information about our Pre-Loaded CTRs, please call us at 800-932-4202 Exclusively from Visit us at AAO Booth 2690

• Cover