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Feature story

Cataract Surgery in With Nonprogressive Toric IOLs can provide excellent outcomes in carefully selected .

By Julián Cezón, MD

erforming in patients with kera- BCVA was 20/40 or better in 83.3% of eyes. Postoperative toconus presents many challenges. In order to mean refractive sphere and cylinder also significantly select the strategy that will lead to the best out- improved from preoperative levels. come, several factors must be considered. These Pinclude whether the has progressive or nonpro- CAREFULLY SELECT PATIENTS gressive keratoconus, how to manage individuals who In a retrospective study of 19 patients implanted have previously undergone , with the T-flex aspheric toric IOL (Rayner Intraocular and if and when to perform intrastromal corneal ring Lenses), 14 carefully selected patients had stable (non- segment placement or corneal crosslinking— progressive) keratoconus. In this study of patients aged before or after IOL implantation—in those with stable 49 to 64 years, the mean preoperative spherical equiva- keratoconus. lent was -6.75 ±5.07 D, and the mean refractive cylinder was -3.85 ±1.67 D. THE CASE FOR TORIC IOLs At 1-month postoperative, 68% had achieved a When a cataract patient presents with stable kera- spherical equivalent between 0.50 and -0.50 D and 95% toconus, one of the first questions the tends between 1.00 and -1.00 D; this result was stable through to ask him or herself is: Which IOL is most suitable? 12 months. The attempted versus achieved spherical Common answers include spherical, toric, and multifo- equivalent was also good. Although there was a slight cal toric lenses. Because keratoconus generates varying undercorrection in patients with high refractive cylinder, degrees of , I believe that toric IOLs should all patients gained at least 3 lines of vision. be given serious consideration for these patients. Toric IOLs are not labeled for use in keratoconus, but TWO IMPORTANT FACTORS some studies have shown promising results.1,2 Visser et Toric IOLs are not suitable for all patients with nonpro- al1 reported that toric IOL implantation in two patients gressive keratoconus, and Figure 1 shows my algorithm with mild to moderate nonprogressive keratoconus cor- for selecting the proper treatment. In my opinion, the two rected astigmatism and improved visual function. UCVA increased from 20/400 to 20/50 bilaterally in the first Take-Home Message patient and from 20/400 to 20/130 in the right and • The two most important factors in determining 20/400 to 20/30 in the left eye in the second patient. In candidacy for toric IOLs are history and stage of the first patient, refractive astigmatism decreased by 70% keratoconus. in both eyes (-6.00 to -1.50 D). • Toric IOLs can be considered in patients with mild Nanavaty et al2 conducted a retrospective, noncom- to moderate keratoconus. If the disease is in an parative study of 12 eyes of nine patients with stable advanced stage and the patient wears rigid contact mild to moderate keratoconus who received a toric IOL. lenses, however, toric IOLs are likely not a good At a mean postoperative follow-up of 9 ±8.8 months, treatment option. distance UCVA was 20/40 or better in 75% of eyes and

April 2014 Cataract & Today Europe 41 Cataract Surgery Feature story

Figure 1. The author’s algorithm of decisions for strategy orientation.

most important factors in determining candidacy for toric been developed to predict IOL power, they can be dif- IOLs are history and stage of keratoconus. ficult to use in everyday practice. Elevation topography Keratoconus history. Not all patients are aware that systems such as the Pentacam (Oculus Optikgeräte), they have keratoconus. In those who do not know, the which provides true net power maps, or the Galilei disease state is usually mild to moderate, and toric IOLs (Ziemer Ophthalmic Group), which allows total cor- can be considered. However, toric IOLs are unlikely to neal mapping, can simplify IOL power calculation in be a good option in patients with a known history of these eyes. Another option with the T-flex IOL is to use keratoconus, especially if they wear rigid contact lenses the Raytrace web-based toric IOL calculator3 (Rayner (RCLs). This is because, in the event that correction of Intraocular Lenses) to calculate IOL power. at surgery is inadequate, it will most likely Regardless of the chosen calculation method, patients be impossible for these patients to resume RCL use. must be informed of the possibility of miscalculation due Keratoconus severity. Patients with mild to moderate to the influence of their keratoconus on postoperative keratoconus (Amsler stage 1 or 2) and stable refractive power. whose vision improves with are likely good candidates for toric IOLs. In , toric IOLs are rarely CONCLUSION considered for patients who have advanced keratoconus Toric IOLs can provide excellent outcomes in care- (Amsler stage 3 or 4) and unstable corneas and in whom fully selected patients with nonprogressive keratoconus. refraction is impossible. Spherical IOLs are more appro- Although these IOLs may not provide total vision correc- priate for these patients. tion, in my experience most patients with keratoconus are pleased with the dramatic improvement they offer. n ADDITIONAL CHALLENGES The corneal apex is decentered in most keratoconus Julián Cezón, MD, is the Director of the patients, but keratometry (K) readings are taken in the Clínica CIMO, de Sevilla, Spain. Dr. Cezón states central . Additionally, standard deviations of the that he has no financial interest in the products differences between the steepest and flattest K read- or companies mentioned. He may be reached at ings can vary from 1.00 to more than 5.00 D in these tel: +34 954230303; fax: +34 954232785; e-mail: patients, irregular astigmatism changes the anterior- [email protected]. to-posterior corneal curvature ratio, and the value of objective astigmatism based on keratometry (K2 minus 1. Visser N, Gast ST, Bauer NJ, Nuijts RM. Cataract surgery with toric intraocular implantation in keratoconus: A case report. Cornea. 2011;30(6):720-723. K1) is usually reduced to more subjective values. For all 2. Nanavaty MA, Lake DB, Daya SM. Outcomes of pseudophakic toric implantation in keratoconic these reasons, calculating IOL power is difficult. eyes with cataract. J Refract Surg. 2012;28(12):884-889. Although complex mathematical algorithms have 3. T-flex Aspheric Toric IOL. Rayner website. http://www.rayner.com/products/t-flex. Accessed March 13, 2014.

42 Cataract & Refractive Surgery Today EUROPE April 2014