Eyeworld

48 This retrospective, non-random- ized, non-comparative case series study comprised 21 eyes of 11 pa- tients who had RK surgery. Their medical charts were reviewed, and data before and after multifocal im- plants through PRELEX surgery were analyzed. All procedures were per- formed at the Khanna Vision Insti- tute, Beverly Hills, following the same surgical protocol. The preoper- ative examination included uncor- rected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest distance refrac- tion, keratometry (IOL scans), and corneal topography. After surgery, patients were treated with a standard combination of antibiotics for a week and steroidal or nonsteroidal drops ta- pered over 6 weeks. Postoperative examinations were done after 1 day, 1 week, 1 month, 2 months, 3 months, and 6 months of Crystalens or ReSTOR implants. At the postop visits, the UDVA, CDVA, manifest refraction, corneal topography, and keratometry readings were recorded. A surgeon performed the examina- tions and an independent observer collected the data. All of the patients with implants reported improvement in distance vision 20/80 or better as some eyes were targeted for mini monovision. More than half of the patients with implants were able to read at least an extra line on the Snellen chart than they could before the implants. The study shows that with proper patient selection and educa- tion, presbyopic implants can yield satisfactory results. Some patients went through YAG and/or LASEK surgeries to achieve 20/20 vision. We are continuing with patient follow- ups and plan to report future out- comes. Refractive lens exchange after RK requires further improve- ment, but it is still an effective pro- cedure. EW References 1. Fyodorov SN, Durven VV. Operation of dosage dissection of corneal circular ligament in cases of myopia of mild degree. Ann Ophthalmol 1979;11:1885–1890. 2. Bores LD. Historical review and clinical results of radial keratotomy. Int Ophthalmol Clin 1983;23: 93–118. 3. Lindstrom RL. Minimally invasive radial keratotomy: Mini-RK. J Cataract Refract Surg. 21(1995), 27–34. 4. Camellin M, Savini G, Hoffer KJ, Carbonelli M, Barboni P. Scheimpflug camera measure- ment of anterior and posterior corneal curva- ture in eyes with previous radial keratotomy. J Refract Surg 2012; 28:275–279. 5. Schanzlin DJ, Santos VR, Waring GO, et al. Diurnal change in refraction, corneal curva- ture, visual acuity and intraocular pressure after radial keratotomy in the PERK study. Ophthalmology 1987; 94: 120–124. 6. Packer M, Fine IH, Hoffman RS. Refractive lens exchange with the Array multifocal intraocular lens. J Cataract Refract Surg 2002;28:421–424. 7. Potvin R, Hill W. New algorithm for post- radial keratotomy intraocular lens power calculations based on rotating Scheimpflug camera data. J Cataract Refract Surg 2013; 39:358–365. 8.Koch DD, Liu JF, Hyde LL, Rock RL, Emery JM. Refractive complications of cataract surgery after radial keratotomy. Am J Ophthalmol 1989; 108:676–682. 9. Newell FW. Introduction to radial keratotomy (Editorial). Am J Ophthalmol 1981; 92(2): 286–291. 10. Waring GO. Radial keratotomy in perspective (Editorial). Am J Ophthalmol 1981; 92(2): 286. 11. Kramer SG. An assessment of radial keratotomy (Editorial). Am J Ophthalmol 1981; 92(2): 291–292. 12. Kaufman HE. Unanswered questions about radial keratotomy (Editorial). Am J Ophthalmol 1981; 92(2): 292–295. 13. Hecht, SD. Radial keratotomy: Is Professor Fyodorov correct? (Editorial). Ann Ophthalmol 1982; 14(4): 313–314. 14. Rowe M. Radial Keratotomy. The Lancet Oct 29, 1994; 1220. 15. Waring GO III, Lynn MJ, McDonnell PJ and the PERK Study Group. Results of the Prospec- tive Evaluation of Radial Keratotomy (PERK) Study 10 Years After Surgery. Arch Ophthalmol 1994; 112:1298–1308. 16. Hoffer KJ. Intraocular lens power calcula- tion for eyes after refractive keratotomy. J Refract Surg 1995; 11:490–493. Editors' note: Dr. Khanna is a voluntary instructor at Jules Eye Stein Institute, Los Angeles, and practices at Khanna Vision Institute, Beverly Hills Surgical Center. Dr. Khanna and Ms. Singh have no related financial interests. Contact information Singh: chinar.singh@gmail.com EW REFRACTIVE SURGERY 48 June 2014 by Rajesh Khanna, MD, and Chinar Singh Results of presbyopic implants in post-radial keratotomy eyes promising R adial keratotomy (RK) was introduced by Prof. Fyodorov in Russia in the year 1973. 1 It triggered an explosion of controversy since its arrival in the United States in 1978 9-12 where more than 10,000 procedures were performed in the subsequent 3 years. 13 The procedure consisted of radial incisions, from the pupil to the limbus. 2 These vertical incisions in the cornea, pen- etrating up to 95% of the patient's corneal depth, 3 caused local steepen- ing and central flattening, thereby reducing the power of the cornea. 4 A 10-year follow-up study found radial keratotomy to be safe but unpre- dictable, in terms of both the short- term and long-term changes in the refractive characteristics of the eye. 14 The findings of the Prospective Eval- uation of Radial Keratotomy (PERK) study were based on 693 eyes (374 patients with operations 1 year apart for those with 2 eyes treated. 15 ) The evaluation of radial keratotomy in the PERK study dealt a death blow to RK, showing that RK had a short- term and long-term instability. 5 Eyes that have undergone RK pose a challenge in calculating IOL power 7 due to the change in the shape of the cornea, especially the relation between the anterior and posterior cornea. According to Hoffer, RK causes a relatively propor- tional flattening of both the front and back surfaces of the central cornea, which leaves the index of refraction relationship the same. 16 Also, a high percentage of RK pa- tients were observed to be signifi- cantly hyperopic after cataract surgery. 8 Special formulae have been developed to accommodate these changes. Presbyopic implants LASIK has raised the expectations of visual outcomes of people undergo- ing eye surgeries. As Baby Boomers have aged and are desiring vision for all distances, it has become increas- ingly challenging to satisfy these needs. People outside the age group qualifying for LASIK have benefited from PRELEX, a term coined by Kevin Waltz, MD, as an acronym for presbyopic refractive lens ex- change. This is a procedure in which a precataractous dysfunctional natu- ral lens is replaced with an artificial lens 6 implant. PRELEX is also re- ferred to as clear lens exchange (CLE) or refractive lens exchange (RLE). Presbyopic implants became popular in this century after the in- troduction of accommodative lenses such as the Crystalens (Bausch + Lomb, Bridgewater, N.J.) and refrac- tive lenses such as the ReSTOR (Alcon, Forth Worth, Texas), ReZoom (Abbott Medical Optics, Santa Ana, Calif.), and Tecnis (Abbott Medical Optics). Work is still being done to prove that presbyopic implants alleviate visual problems and eliminate the need for glasses, but they may offer a solution to the problems of vision. Our study Unable to find research papers and intensive studies regarding the intro- duction of multifocal implants following radial keratotomy, we con- ducted a retrospective study (now in print) that included patient follow- up of up to 6 months. Patient charts with records of multifocal corneas, headed for corneal transplant, were excluded from this study. Rajesh Khanna, MD Chinar Singh 48-50 Refractive_EW June-DL_Layout 1 6/3/14 12:36 PM Page 48

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