EyeWorld Asia-Pacific September 2011 Issue

34 EW CATARACT/IOL September 2011 Lens calculations are not as easy in this group of patients, but a carefully planned strategy can yield optimal visual results P atients who have both cataract and keratoconus present some unique challenges for the surgeon, including lens choice and general IOL calculations. Oftentimes in these eyes, measured Ks are not as accurate as manual keratometry can be. Toric lenses may be helpful, but they, too, have limits in this patient group. “The best results from toric IOLs come from patients who have regular, symmetric, and stable corneal astigmatism,” said Uday Devgan, MD, chief of ophthalmology, Olive View– University of California, Los Angeles Medical Center, Sylmar, Calif., USA, and Devgan Eye Surgery, Los Angeles, Calif., USA. “If the corneal astigmatism is irregular, asymmetric, or unstable, then the results will not be nearly as good or predictable.” Robert M. Jaffee, MD, Jaffee Eye Associates, Middletown, NY, USA, recently saw a 50-year- old patient with both cataract and keratoconus. As he noted, “The patient is –9.50 OD [right eye], –14.50 OS [left eye]. The K readings are 44.50x46.50 OD and 44.25x50.00 OS. Further, he has a posterior subcapsular cataract OS but only trace OD and has 20/20 [6/6] vision in the OD.” Dr. Jaffee said this particular patient used contact lenses (–8.00 on the OD). The first question to address in patients like this is whether or not to even use a toric lens, and if you do choose to use a toric lens what the post-op refractive error should be, Dr. Devgan said. Combining cataract and keratoconus treatment by Michelle Dalton EyeWorld Contributing Editor A patient with keratoconus An example of a patient with keratoconus; the bulging cornea is obvious A patient with keratoconus with steep curvature identified Source: Uday Devgan, MD Views from Asia-Pacific Chul Young CHOI, MD Assistant Professor, School of Medicine, Sung Kyun Kwan University Cornea & Refractive Surgery Services, Department of Ophthalmology, Kangbuk Samsung Hospital 108 Pyoung Dong, Jongno-Ku, Seoul, Korea 110-746 Tel. no. +82220012444 Fax no. +82220012262 sashimi0@naver.com T oric IOLs have been described as an effective option for the correction of high myopic astigmatism with stable keratoconus and cataract at the same time. In addition, in patients with combined cataract and keratoconus, toric IOLs may be a safe and effective option to correct refractive errors in nonprogressive keratoconus. Also, some authors have recently described the use of phakic anterior chamber intraocular lenses (IOLs) to treat refractive errors associated with keratoconus, which shows great effectiveness. Before implanting the toric IOL, accurate axial length, K-values, and astigmatism axis measurements must be obtained to calculate accurate IOL power. And the patients’ individual risk of progression should be analyzed. Risk factors that have been associated with progression of keratoconus include young age, a family history of keratoconus, steep keratometric values, changes in refractive error, and possibly eye rubbing. In determining the axis of the toric IOL, there may be two different axes (skewed radial axes) in keratoconic eyes. Interestingly, axis mismatching caused by “skew deviation” would not considerably impair the visual outcome. Because the usual range of deviation is not significant in most central keratoconus, and in case of deviations more than 10 degrees, a third of the astigmatism effect will disappear by its own characteristics of toric IOL. The clinical outcomes of toric IOLs in patients with keratoconus will vary considerably. In case of central keratoconus with minimal risk of progression, a toric IOL may be worthy of recommendation. But in cases of advanced inferior ectasia, recently diagnosed keratoconus, or younger patients with progression, implantation of toric IOLs can create a new optical problem, which may not be corrected by a contact lens In these cases, cataract surgery with toric IOL should be delayed and surgical options including collagen crosslinking, intrastromal segmental ring implantation, and keratoplasty could be recommended. In the near future, with the help of markedly developed wavefront technology, we can expect the individually customized IOLs such as light-adjustable technology to correct cataract patients with keratoconus. These kinds of IOLs will also be helpful to correct the individual wavefront errors, irregular astigmatisms originating from previous corneal surgeries. Editors’ note: Prof. Choi has no financial interests related to his comments.