Eyeworld

EW RESIDENTS 52 July 2014 by Zachary Joos, MD, Trent Richards, MD, Brian Zaugg, MD, residents, and Mark Mifflin, MD, education director, Moran Eye Center, University of Utah Review of "Refractive accuracy with light-adjustable intraocular lenses" this study of the Calhoun light- adjustable IOL, which appears in the current JCRS issue. –David F. Chang, MD, chief medical editor Introduction Cataract surgery has undergone sig- nificant advances in recent history. Now more than ever, there is an ex- pectation for emmetropia following cataract surgery. Many formulas exist for intraocular lens (IOL) selec- tion, and while these are generally useful, deviation from the target refractive goal is not uncommon. Many factors contribute to the lack of predictability, and these include measurement or calculation errors (especially corneal curvature and effective lens position), surgical pre- cision, and patient characteristics such as prior refractive surgery, vari- able wound healing, ocular surface disease, and even neuroadaptation. A variety of treatments have been used to treat residual refractive error after cataract surgery. Glasses, con- tact lenses, incisional keratotomy, corneal laser vision correction, con- ductive keratoplasty, IOL exchange, and piggyback IOLs have all been used successfully. Light-adjustable IOLs have been studied for many years and now provide another modality to correct remaining refractive errors after cataract sur- gery. The light-adjustable IOL used in this study (LAL, Calhoun Vision, Pasadena, Calif.) contains photosen- sitive macromer molecules that physically move and change posi- tion inside the IOL in response to ir- radiation with ultraviolet light. This causes a change in shape of the IOL, which results in the desired refrac- tive correction. Previous studies in animals have shown predictable ability to correct defocus and astig- matism by varying the spatial pro- file, intensity, and duration of the ultraviolet exposure. One or more initial treatments or adjustments are performed, followed by later "lock- in" treatments. The posterior surface of the IOL has a UV light-filtering layer to provide protection to the retina against the UV light used during the irradiation procedure. Methods The current study is the first to look at the performance of the Calhoun LAL in a large number of human cataract patients. The investigators studied the refractive changes and stability of the whole eye and the light-adjustable IOL after treatments with different profiles to correct my- opia, hyperopia, and astigmatism. The authors studied visual acuity and changes in refraction at 3, 6, and 12 months postop in 53 eyes (49 patients) that underwent cataract surgery with the light-ad- justable IOL at the Virgen de la Arrixaca Hospital in Murcia, Spain. All surgeries were performed by the same surgeon with the same surgical technique. Methods for patient se- lection, patient demographics, and past ocular history of the patients were not discussed. Postoperative myopia, hyperopia, and astigmatism were treated beginning at 2 weeks using the appropriate treatment profiles. In emmetropic patients a neutral profile was used to stabilize the IOL before the lock-in treat- ments were performed. Due to limits of astigmatism correction, patients with preoperative corneal astigma- tism higher than 2.0 D were not included. The first lens adjustment Perhaps the ultimate refractive IOL would be one that could be precisely adjusted postoperatively, and there are several such technologies being developed. This month I invited Utah's Moran Eye Center residents to review Mark Mifflin, MD Brian Zaugg, MD Trent Richards, MD Zachary Joos, MD Refractive accuracy with light-adjustable intraocular lenses Eloy A. Villegas, PhD, Encarna Alcon, MSc, Elena Rubio, MD, José M. Marín, MD, PhD, Pablo Artal, PhD J Cataract Refract Surg (July) 2014;40:1075–1084 Purpose: To evaluate efficacy, predictability, and stability of refractive treatments using light-adjustable intraocular lenses (IOLs). Setting: University Hospital Virgen de la Arrixaca, Murcia, Spain. Design: Prospective nonrandomized clinical trial. Methods: Eyes with a light-adjustable IOL (LAL) were treated with spatial intensity profiles to correct refractive errors. The effective changes in refraction in the light-adjustable IOL after every treatment were estimated by subtracting those in the whole eye and the cornea, which were measured with a Hartmann-Shack sensor and a corneal topographer, respectively. The refractive changes in the whole eye and light-adjustable IOL, manifest refraction, and visual acuity were obtained after every light treatment and at the 3-, 6-, and 12-month follow-ups. Results: The study enrolled 53 eyes (49 patients). Each tested light spatial pattern (5 spherical; 3 astigmatic) produced a different refractive change (P<.01). The combination of 2 light adjustments induced a maximum change in spherical power of the light-adjustable IOL of between −1.98 diopters (D) and +2.30 D and in astigmatism of up to −2.68 D with axis errors below 9 degrees. Intersubject variability (standard deviation) ranged between 0.10 D and 0.40 D. The 2 required lock-in procedures induced a small myopic shift (range +0.01 to +0.57 D) that depended on previous adjustments. Conclusions: Light-adjustable IOL implantation achieved accurate refractive outcomes (around emmetropia) with good uncorrected distance visual acuity, which remained stable over time. Further refinements in nomograms and in the treatment's protocol would im- prove the predictability of refractive and visual outcomes with these IOLs. Financial disclosure(s): No author has a financial or proprietary interest in any material or method mentioned. EyeWorld journal club 50-53 Residents_EW July 2014-DL_Layout 1 6/30/14 8:49 AM Page 52

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