# Calculation of intraocular lens (IOL) power for

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 A New Method of Calculating Intraocular Lens Power After Photorefractive Keratectomy Nicola Rosa, MD; Luigi Capasso, MD; Antonio Romano, MD ABSTRACT PURPOSE: To find a method of calculating intraocular lens (IOL) power that may be independent of preoperative data, in eyes that have developed a cataract after refractive surgery. METHODS: Prior to and 1 month after PRK, the SRK/T formula was used to calculate IOL power in 88 eyes of 65 patients with a preoperative spherical equivalent refraction between to D (mean ± 3.19 D). IOL power was calculated by utilizing the spherical equivalent refraction as target both before and after PRK. Utilizing the postoperative corneal radius measurement (R2), an underestimation of the IOL power was found. For this reason, the mean postoperative corneal radius (R3) that gave the same IOL power found before surgery was calculated for each patient. The R3/R2 ratios were plotted against the axial eye length and a linear regression formula was used to calculate R2 correcting factors that gave the new corneal radius (R4). Patients were divided into classes according to axial eye length, and the mean R3/R2 ratios for each class were calculated and used to recalculate the new mean radius (R5). IOL power for emmetropia was calculated in all patients by utilization of R3, R4, R5, the historical method, and the true corneal power method. RESULTS: Within ±0.50 D from the IOL power calculated with R3, R4 gave 35 (39.3%) IOLs, while R5 gave 40 (45.5%) IOLs; the clinical history method gave 24 (27.3%) IOLs and true corneal power gave 23 (26.1%) IOLs, with a statistically significant difference P<.001). CONCLUSIONS: Our theoretical method, based on correlation between axial eye length and corneal radius correcting factors, may represent an effective method of calculating IOL power after PRK, especially if the history of the patient is unknown. [J Refract Surg 2002;18: ] From the Eye Department, 2nd University of Naples, Naples, Italy. The authors have no proprietary interest in the materials mentioned herein. Correspondence: Nicola Rosa, MD, Dipartimento di Oftalmologia, II Università degli Studi di Napoli, Via Pansini 5, Napoli, Italy. Tel: ; Fax: ; Received: November 19, 2001 Accepted: April 15, 2002 Calculation of intraocular lens (IOL) power for patients undergoing cataract surgery is mainly based on the measurement of the corneal power, axial eye length, and estimation of the effective lens position. 1 Over the years, several formulae have been proposed to make this calculation, and nowadays the so-called third generation formulae are considered to be those that obtain the best results in terms of IOL power prediction. After refractive surgery for myopia, both keratometry and corneal topography tend to overestimate the corneal power 2-7, and consequently the calculated IOL power is underestimated, as has been described To overcome this problem, several techniques have been proposed, most of which require knowing the preoperative keratometric power and the exact amount of treatment, and regrettably in most patients such information is not available. The purpose of our study was to find a method that could give reliable results even for these patients. PATIENTS AND METHODS Eighty-eight eyes of 65 patients (29 males and 36 females) consecutively treated with photorefractive keratectomy (PRK) for myopia, or myopic or mixed astigmatism were included in this non-randomized, prospective clinical study. The age of the patients at the time of refractive surgery ranged between 19 and 56 years (mean 33.5 ± 9.2 yr). Patients were asked to discontinue wearing contact lenses for at least 1 month before undergoing the last refractive evaluation, which was performed the day the patient underwent PRK. Before and 1 month after treatment, all patients underwent a complete ophthalmic examination, including automatic keratometry and axial eye length measurement with an IOL Master (Zeiss, Jena, Germany). Patients with systemic and ocular diseases that could potentially interfere with the healing process of the cornea or with refractive 720 Journal of Refractive Surgery Volume 18 November/December 2002

2 outcome (eg, diabetes, collagenopathies, dry eyes, uveitis, corneal and lens opacities, glaucoma) were not included in the study. Treatments for sphere and cylinder were performed by combining objective and subjective refraction, thereby achieving the best corrected visual acuity. Whenever a discrepancy between keratometric and subjective (clinical) cylindrical data was noted, we used the subjective refraction cylinder data and not the keratometric data for planning the refractive procedure All treatments were performed under topical anesthesia with oxybuprocaine eye drops (Novesina, Novartis Farma, Italy). The lids were opened with a speculum, the epithelium was debrided with mechanical brush epithelial removal, and all treatments were performed with a 193-nm excimer laser (Nidek EC-5000, Gamagori, Japan) operating in scanning mode. After treatment, a smoothing of the surface was performed using 0.04% hyaluronic acid. A bandage contact lens was applied under sterile conditions on the treated eye immediately following surgery, and was not removed until complete reepithelialization. During this period, operated eyes received diclofenac sodium 0.1% eye drops twice a day for the first 2 days, nethylmicin preservativefree eye drops until re-epithelialization, and preservative-free artificial tears for 1 month; after reepithelialization, clobetasone eye drops were prescribed to all patients for 1 month in a tapered dose, as follows: one drop four times a day for the first week, one drop three times a day for the second week, one drop two times a day for the third week, and one drop once a day for the last week. For all patients, we postulated that the lens power before and after PRK would not change, since with PRK we treat the corneal surface and not the lens. Before and after PRK, the SRK/T formula was used to calculate the power of a standard IOL (Memorylens [CIBA Vision, Duluth, GA], foldable, 6.0-diameter, with a recommended A constant of 119, and anterior chamber depth of 5.6 mm), utilizing as target the spherical equivalent refractive error before and after PRK (eg, if a patient had a spherical equivalent refraction of diopters (D) before PRK and D after PRK, we used as target D before PRK, and after PRK) utilizing the preoperative (K1) and postoperative (K2) keratometric power (Fig 1). Because an underestimation was found between these two values (Fig 1), we calculated a mean keratometric power (K3) for each patient, which gave Figure 1. Correlation between IOL power calculated before and after PRK utilizing as target the preoperative and postoperative refractive error. Figure 2. Correlation between the R3/R2 ratios and the axial eye length. the same IOL power we had determined before surgery. From K3, we calculated the corneal radius (R3) by utilizing n = (according to the Zeiss IOL Master). At this point, we calculated a ratio between the calculated radius (R3) and the measured postoperative radius (R2) for each patient and correlated them with one easily available postoperative parameter, the axial eye length. We found a fairly good correlation (r 2 = ) between axial eye length and these ratios with a linear correlation formula (Y= X ) (Fig 2). We used this linear regression formula to calculate the correcting factors which, when multiplied Journal of Refractive Surgery Volume 18 November/December

3 Table 1 Correcting Factors for Calculating Corneal Radius According to Axial Length of the Eye Axial Eye Length (mm) Correcting Factor 22 to to to to to to to by R2, gave the new radius (R4). We also divided the patients into classes according to axial eye length, and calculated the mean ratio for each class (Table 1), which we used to calculate mean radius (R5). R4 and R5 were then utilized to calculate different IOL powers for emmetropia in all patients. To test the reliability of our methods we compared our results with those obtained with the historical method 16,17 and with the true corneal power 18 method and tested the differences with a paired t-test. To further validate our results, we tested our method with the data of some cases reported in the literature 9-11, and in particular we calculated with our formulas the expected postoperative refractive error by utilizing the power of the implanted IOL. RESULTS Before PRK, the refraction of the patients ranged between and D (mean ± 3.21 D) of sphere, the cylindrical power between and 0 D (mean ± 1.22 D), and the spherical equivalent refraction between and D (mean ± 3.19 D). One month after PRK, the refraction ranged between and D (mean 0.88 ± 0.83 D) of sphere, the cylindrical power between and D (mean ± 0.46 D), and the spherical equivalent refraction between and D (mean ± 0.88 D). The IOL values obtained after PRK showed an underestimation compared to those obtained after PRK (Fig 1). The IOLs for emmetropia calculated by utilizing the historical method and the true corneal power were underestimated compared to the IOLs calculated with R3 (Figs 3, 4). The number of eyes that showed ±0.50 D and ±1.00 D of difference and the Figure 3. Correlation between IOL power calculated utilizing the historical method and those obtained utilizing R3. Figure 4. Correlation between IOL power calculated utilizing the true corneal power method, and those obtained utilizing R3. mean differences between calculations (the measured radius, R4, R5, historical method, and true corneal power) and the true IOL power (utilizing R3) are shown in Table 2. The differences obtained with R4 and R5 were significantly smaller than those obtained with the other two methods (P<.001). With our methods, we calculated the expected postoperative refractive errors by utilizing the implanted IOL in the cases described by Siganos and colleagues 9 and Morris and colleagues 11, shown in Table Journal of Refractive Surgery Volume 18 November/December 2002

4 Table 2 Number (%) of Eyes Between ±0.50 D and ±1.00 D of Theoretical IOL Power, Utilizing Correcting Factors and Historical Method; Difference Between IOL Power Calculated With Different Methods and the Theoretical IOL Power Method of ±0.50 D ±1.00 D Mean Calculation Difference (D) R4* 35 (39.77) 50 (56.82) 0.20 ± 2.87 R5 40 (45.45) 58 (65.91) ± 1.46 Historical method 24 (26.13) 49 (55.68) 1.14 ± 0.86 True corneal power 23 (26.14) 40 (45.45) 1.81 ± 2.01 *R4: new corneal radius obtained with regression formula R5: new corneal radius obtained from classes of axial eye length Table 3 Expected Refractive Error Calculated With SRK/T Formula and R4 or R5, With the Implanted IOL Authors Implanted IOL Refractive R4* R5 Power (D) Error (D) (D) (D) Siganos et al Morris et al *Expected refractive error calculated with SRK/T formula and R4, with the implanted IOL Expected refractive error calculated with SRK/T formula and R5, with the implanted IOL DISCUSSION Keratometry and corneal topography analyses have been reported to underestimate corneal power changes by 20% to 30% after PRK. 4 For this reason, underestimations of IOL power calculations in the case of patients who had undergone cataract extraction with IOL implantation after PRK have been described. Three main methods of overcoming this problem have been described: the clinical history method, the contact lens method, and the true corneal power method. Clinical History Method This method was described by Guyton 16 and Holladay 17 in 1989 for eyes after refractive keratotomy, and later by Hoffer. 18 This method, based on refraction-derived keratometric values, requires the knowledge of three parameters 19 : preoperative corneal power, preoperative, and postoperative refraction. Calculation of True Corneal Power Most videokeratography and standard keratometry convert the corneal radius into corneal power by using the standardized keratometric index of This index is invalid after PRK and laser in situ keratomileusis (LASIK) because these procedures change the relationship between the anterior and posterior surface of the cornea. 19 However, there is no agreement on the value to be used in these cases, as some authors 20,21 suggest using n = 1.376, and others 22 suggest the higher value n = Contact Lens Overcorrection This method, described by Soper and Goffman 23, is based on three parameters 19 : base curve of plano contact lens in diopters, spherical equivalent refraction without contact lenses, and contact lens overrefraction. This method is slightly less accurate than standard keratometry for determining corneal powers in persons with normal corneas, clear media, and good visual acuity and can be performed in a person in which no knowledge of the preoperative parameters is available, but unfortunately is not reliable if the media opacities give visual acuity worse than 20/ In our opinion, the clinical history method and the calculation of the true corneal power seem accurate and easy to calculate. However, with regard to the clinical history method, PRK has been performed on many patients in different surgical centers, and the preoperative keratometric power and the exact amount of PRK correction are regrettably unavailable. We found a poor correlation with regard to the true corneal power method. Among the existing formulae, we decided to use the SRK/T because this third generation formula seems to be more accurate for IOL calculation. In our study, we correlated axial eye length, an easily available measurement, to the amount of treatment, since we assumed that in most patients there is an axial myopia; we excluded from the study patients with lens opacities or with keratoconus. Even if our two methods need to be tested in a large prospective evaluation to assess validity and determine which one is best, the one with correction factors related to axial eye length showed a slightly better correlation (r 2 = ) compared with the linear regression formula (r 2 = ). We think that our methods, which are based on a radius of curvature correcting factor related to the Journal of Refractive Surgery Volume 18 November/December

5 axial eye length, might represent an effective method of calculating IOL power after PRK if preoperative keratometric power or the amount of treatment are unknown. REFERENCES 1. Seitz B, Langenbucher A. Intraocular lens power calculation in eyes after corneal refractive surgery. J Refract Surg 2000;16: Koch DD, Liu JF, Hyde LL, Rock LL, Emery JM. Refractive complications of cataract surgery after radial keratotomy. Am J Ophthalmol 1989;108: Rosa N, Cennamo G, Pasquariello A, Maffulli F, Sebastiani A. Refractive outcome and corneal topographic study after photorefractive keratectomy with different sized ablation zones. Ophthalmology 1996:103: Rosa N, Cennamo G, Rinaldi M. Correlation between refractive and corneal topographic changes after photorefractive keratectomy for myopia. J Refract Surg 2001;17: Smith RJ, Chan W-K, Maloney RK. The prediction of surgically induced refractive change from corneal topography. Am J Ophthalmol 1998;125: Seitz B, Langenbucher A, Nguyen NX, Kus MM, Kuchle M. Underestimation of intraocular lens power for cataract surgery after myopic photorefractive keratectomy. Ophthalmology 1999;106: Peter R, Hazeghi M, Job O, Wienecke L, Schipper I. Manual keratometry and videokeratography after photorefractive keratectomy. J Cataract Refract Surg 2000;26: Lesher MP, Schumer DJ, Hunkeler JD, Durrie DS, McKee FE. Phacoemulsification with intraocular lens implantation after excimer photorefractive keratectomy: a case report. J Cataract Refract Surg 1994;20:S265-S Siganos DS, Pallikaris IG, Lambropoulos JE, Koufala CJ. Keratometric readings after photorefractive keratectomy are unreliable for calculating IOL power. J Refract Surg 1996;20:S278-S Kalski RS, Danjoux JP, Fraenkel GE, Lawless MA, Rogers C. Intraocular lens power calculation for cataract surgery after photorefractive keratectomy for high myopia. J Refract Surg 1997;13: Morris AHC, Whittaker KW, Morris RJ, Corbett MC. Errors in intraocular lens power calculation after photorefractive keratectomy. Eye 1998;12: Speicher L, Gottinger W. Intraocular lens power calculation after decentered photorefractive keratectomy. J Cataract Refract Surg 1999;25: Gimbel H, Sun R, Kaye GB. Refractive error in cataract surgery after previous refractive surgery. J Cataract Refract Surg 2000;26: Gimbel HV, Sun R, Furlong MT, van Westenbrugge JA, Kassab J. Accuracy and predictability of intraocular lens power calculation after photorefractive keratectomy. J Cataract Refract Surg 2000;26: Ladas JG, Boxer Wachler BS, Hunkeler JD, Durrie DS. Intraocular lens power calculations using corneal topography after photorefractive keratectomy. Am J Ophthalmol 2001;132: Guyton DL. Consultations in refractive surgery. Refract Corneal Surg 1989;5: Holladay JT. Consultations in refractive surgery. Refract Corneal Surg 1989;5: Hoffer KJ. Intraocular lens power calculation for eyes after refractive keratotomy. J Refract Surg 1995;11: Speicher L. Intra-ocular lens calculation status after corneal refractive surgery. Curr Opin Ophthalmol 2001;12: Mandell RB. Corneal power correction factor for photorefractive keratectomy. J Refract Corneal Surg 1994;10: Gobbi PG, Carones F, Brancato R. Keratometric index, videokeratography, and refractive surgery. J Cataract Refract Surg 1998;24: Hugger P, Kohen T, La Rosa F, Holladay JT, Koch DD. Comparison of changes in manifest refraction and corneal power after photorefractive keratectomy. Am J Ophthalmol 2000;129: Soper JW, Goffman J. Contact lens fitting by retinoscopy. In Soper JW, ed. Contact Lenses: Advances in Design, Fitting Application. Miami, FL: Simposia Specialists; Zeh WG, Koch DD. Comparison of contact lens overrefraction and standard keratometry for measuring corneal curvature in eyes with lenticular opacity. J Cataract Refract Surg 1999;25: Journal of Refractive Surgery Volume 18 November/December 2002

### Comparison of Corneal Power and Intraocular Lens Power Calculation Methods after LASIK for Myopia. Abstract

Comparison of Corneal Power and Intraocular Lens Power Calculation Methods after LASIK for Myopia Seyed Mohammad Reza Taheri, MD 1 Azita Kheiltash, MD, MPH 2 Hassan Hashemi, MD 1,3 Abstract Purpose: To

### COMPARISON OF INTRAOCULAR LENS POWER CALCULATION METHODS IN EYES THAT HAVE UNDERGONE LASER-ASSISTED IN-SITU KERATOMILEUSIS

COMPARISON OF INTRAOCULAR LENS POWER CALCULATION METHODS IN EYES THAT HAVE UNDERGONE LASER-ASSISTED IN-SITU KERATOMILEUSIS BY Li Wang MD PhD, Marc A. Booth MD, AND Douglas D. Koch MD* ABSTRACT Purpose:

### No-history method of intraocular lens power calculation for cataract surgery after myopic laser in situ keratomileusis

J CATARACT REFRACT SURG - VOL 33, JANUARY 2007 No-history method of intraocular lens power calculation for cataract surgery after myopic laser in situ keratomileusis H. John Shammas, MD, Maya C. Shammas,

### Robert A. Latkany, MD, Amit R. Chokshi, MD, Mark G. Speaker, MD, PhD, Jodi Abramson, MD, Barrie D. Soloway, MD, Guopei Yu, MD, MPH

Intraocular lens calculations after refractive surgery Robert A. Latkany, MD, Amit R. Chokshi, MD, Mark G. Speaker, MD, PhD, Jodi Abramson, MD, Barrie D. Soloway, MD, Guopei Yu, MD, MPH Purpose: To evaluate

### LASER IN SITU KERATOMILEUSIS (LASIK) IS GAINING IN

Correcting the Corneal Power Measurements for Intraocular Lens Power Calculations After Myopic Laser In Situ Keratomileusis H. JOHN SHAMMAS, MD, MAYA C. SHAMMAS, BS, ANTOINE GARABET, MD, JENNY H. KIM,

### INTRODUCTION. Trans Am Ophthalmol Soc 2006;104:402-413

ORBSCAN II ASSISTED INTRAOCULAR LENS POWER CALCULATION FOR CATARACT SURGERY FOLLOWING MYOPIC LASER IN SITU KERATOMILEUSIS (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS) BY Henry Gelender MD ABSTRACT Purpose:

### Intraocular Lens Power Calculation after Myopic Refractive Surgery

Intraocular Lens Power Calculation after Myopic Refractive Surgery Theoretical Comparison of Different Methods Giacomo Savini, MD, Piero Barboni, MD, Maurizio Zanini, MD Objective: To evaluate the reliability

### Simple regression formula for intraocular lens power adjustment in eyes requiring cataract surgery after excimer laser photoablation

J CATARACT REFRACT SURG - VOL 32, MARCH 26 Simple regression formula for intraocular lens power adjustment in eyes requiring cataract surgery after excimer laser photoablation Samuel Masket, MD, Seth Everett

### IOL Calculation After LASIK. Chapter (3)

the cornea (P) may be considered as the sum of the power of the anterior (Pa) and posterior (Pp) corneal surfaces, as shown in the formula: P = Pa + Pp = (n2 n1)/r1 + (n3 n2)/r2, where n1 is the refractive

### IOL Power Calculation After Myopic LASIK. Hany Helaly, Lecturer of Ophthalmology, Faculty of Medicine, Alexandria University.

IOL Power Calculation After Myopic LASIK Hany Helaly, Lecturer of Ophthalmology, Faculty of Medicine, Alexandria University. SUPERVISORS Prof. Dr. Mohammad El-Hifnawy Professor of Ophthalmology Faculty

### Total Corneal Power Estimation: Ray Tracing Method versus Gaussian Optics Formula PATIENTS AND METHODS

Cornea Total Corneal Power Estimation: Ray Tracing Method versus Gaussian Optics Formula Li Wang, 1 Ashraf M. Mahmoud, 2 Betty Lise Anderson, 3 Douglas D. Koch, 1 and Cynthia J. Roberts 2 PURPOSE. To evaluate

### articles Intraocular lens power calculation after corneal refractive surgery: Double-K method Jaime Aramberri, MD

articles Intraocular lens power calculation after corneal refractive surgery: Double-K method Jaime Aramberri, MD Purpose: To determine the accuracy of a method of calculating intraocular lens (IOL) power

### Corneal Power Measurements Using Scheimpflug Imaging in Eyes With Prior Corneal Refractive Surgery

Corneal Power Measurements Using Scheimpflug Imaging in Eyes With Prior Corneal Refractive Surgery Jack T. Holladay, MD, MSEE, FACS; Warren E. Hill, MD, FACS; Andreas Steinmueller, MSc ABSTRACT PURPOSE:

### Intraocular lens power calculation after corneal refractive surgery Sachin D. Kalyani, Alisa Kim and John G. Ladas

Intraocular lens power calculation after corneal refractive surgery Sachin D. Kalyani, Alisa Kim and John G. Ladas Department of Ophthalmology, Wilmer Ophthalmologic Institute, Johns Hopkins School of

### Overview of Refractive Surgery

Overview of Refractive Surgery Michael N. Wiggins, MD Assistant Professor, College of Health Related Professions and College of Medicine, Department of Ophthalmology Jones Eye Institute University of Arkansas

### EUROPEAN JOURNAL OF PHARMACEUTICAL AND MEDICAL RESEARCH www.ejpmr.com

ejpmr, 2015,2(3), 436-440 EUROPEAN JOURNAL OF PHARMACEUTICAL AND MEDICAL RESEARCH www.ejpmr.com Tumram et al. SJIF Impact Factor 2.026 Research Article ISSN 3294-3211 EJPMR CLINICAL OUTCOME OF TORIC IOL

### Customized corneal ablation can be designed. Slit Skiascopic-guided Ablation Using the Nidek Laser. Scott MacRae, MD; Masanao Fujieda

Slit Skiascopic-guided Ablation Using the Nidek Laser Scott MacRae, MD; Masanao Fujieda ABSTRACT PURPOSE: To present the approach of using a scanning slit refractometer (the ARK 10000) in conjunction with

### CLINICAL SCIENCES. A Direct Method to Measure the Power of the Central Cornea After Myopic Laser In Situ Keratomileusis

CLINICAL SCIENCES A Direct Method to Measure the Power of the Central Cornea After Myopic Laser In Situ Keratomileusis Sergio Sónego-Krone, MD; Gerson López-Moreno, MD; Oscar V. Beaujon-Balbi, MD; Carlos

### Corneal Refractive Power Estimation and Intraocular Lens Calculation after Hyperopic LASIK

Corneal Refractive Power Estimation and Intraocular Lens Calculation after Hyperopic LASIK Shady T. Awwad, MD, 1,2 Patrick S. Kelley, MD, 1 R. Wayne Bowman, MD, 1 H. Dwight Cavanagh, MD, PhD, 1 James P.

### Estimation of true corneal power after keratorefractive surgery in eyes requiring cataract surgery: BESSt formula

J CATARACT REFRACT SURG - VOL 32, DECEMBER 2006 ARTICLES Estimation of true corneal power after keratorefractive surgery in eyes requiring cataract surgery: BESSt formula Edmondo Borasio, MedCBQ Ophth,

### Original Articles. Laser in situ Keratomileusis to Correct Residual Myopia After Cataract Surgery

Original Articles Laser in situ Keratomileusis to Correct Residual Myopia After Cataract Surgery Maria J. Ayala, MD, PhD; Juan J. Pérez-Santonja, MD; Alberto Artola, MD, PhD; Pascual Claramonte, MD; Jorge

### Retreatment by Lifting the Original Laser in Situ Keratomileusis Flap after Eleven Years

Retreatment by Lifting the Original Laser in Situ Keratomileusis Flap after Eleven Years Hassan Hashemi, MD 1,2 Mehrdad Mohammadpour, MD 3 Abstract Purpose: To describe a case of successful laser in situ

### Case Reports Post-LASIK ectasia treated with intrastromal corneal ring segments and corneal crosslinking

Case Reports Post-LASIK ectasia treated with intrastromal corneal ring segments and corneal crosslinking Kay Lam, MD, Dan B. Rootman, MSc, Alejandro Lichtinger, and David S. Rootman, MD, FRCSC Author affiliations:

### final corrected draft

Archived at the Flinders Academic Commons http://dspace.flinders.edu.au/dspace/ This is the author s final corrected draft of this article. It has undergone peer review. Citation for the publisher s version:

### KERATOCONUS IS A BILATERAL, ASYMMETRIC, CHRONIC,

Comparison of and Intacs for Keratoconus and Post-LASIK Ectasia MUNISH SHARMA, MD, AND BRIAN S. BOXER WACHLER, MD PURPOSE: To evaluate the efficacy of single-segment Intacs and compare with double-segment

### Wavefront-guided Custom Ablation for Myopia Using the NIDEK NAVEX Laser System

Wavefront-guided Custom Ablation for Myopia Using the NIDEK NAVEX Laser System Jan Venter, MD ABSTRACT PURPOSE: To determine the predictability, effi cacy, safety, and stability of LASIK using custom ablation

### To toric or not to toric? A cautionary tale

To toric or not to toric? A cautionary tale Amanda Maltry, MD; Anna Kitzmann, MD; Christine Sindt, OD 1/10/2013 Chief complaint: Decreased vision after cataract surgery History of present illness: 65 year

### The pinnacle of refractive performance.

Introducing! The pinnacle of refractive performance. REFRACTIVE SURGERY sets a new standard in LASIK outcomes More than 98% of patients would choose it again. 1 It even outperformed glasses and contacts

### Insert to October 2013 THE COMPLETE PICTURE. Experiences with the ALADDIN system. Sponsored by Topcon

Insert to October 2013 THE COMPLETE PICTURE Experiences with the ALADDIN system Sponsored by Topcon THE COMPLETE PICTURE Advantages of The Aladdin How this all-in-one optical biometer edged out the IOLMaster

### Treatment of Myopia and Myopic Astigmatism by Customized Laser In Situ Keratomileusis Based on Corneal Topography

Treatment of Myopia and Myopic Astigmatism by Customized Laser In Situ Keratomileusis Based on Corneal Topography Michael C. Knorz, MD, 1 Thomas Neuhann, MD 2 Objective: To evaluate the predictability,

### LASIK SURGERY IN AL- NASSIRYA CITY A CLINICOSTATISTICAL STUDY

Thi-Qar Medical Journal (TQMJ): Vol(4) No(4):1(14-21) SUMMARY: LASIK SURGERY IN AL- NASSIRYA CITY A CLINICOSTATISTICAL STUDY Dr. Ali Jawad AL- Gidis (M.B.Ch.B., D.O., F.I.C.O.)* Background: LASIK which

### Life Science Journal 2014;11(9) http://www.lifesciencesite.com. Cross cylinder Challenging cases and their resultswith Nidek Quest (EC-5000)

Cross cylinder Challenging cases and their resultswith Nidek Quest (EC-5000) Gamal Mostafa Abo El Maaty, Mohamed Elmoddather, Mahmoud Ibrahem Ghazy, Mohamed Al-Taher Ophthalmology Department, Faculty of

### Comparison of Two Procedures: Photorefractive Keratectomy Versus Laser In Situ Keratomileusis for Low to Moderate Myopia

Comparison of Two Procedures: Photorefractive Keratectomy Versus Laser In Situ Keratomileusis for Low to Moderate Myopia Jae Bum Lee, Jae Sung Kim, Chul-Myong Choe, Gong Je Seong and Eung Kweon Kim Institute

### Active Cyclotorsion Error Correction During LASIK for Myopia and Myopic Astigmatism With the NIDEK EC-5000 CX III Laser

Active Cyclotorsion Error Correction During LASIK for Myopia and Myopic Astigmatism With the NIDEK EC-5000 CX III Laser Sudhank Bharti, MD; Harkaran S. Bains ABSTRACT PURPOSE: To investigate the predictability

### Refractive Surgery. Evolution of Refractive Error Correction

Refractive Surgery Techniques that correct for refractive error in the eye have undergone dramatic evolution. The cornea is the easiest place to place a correction, so most techniques have focused on modifying

### Biometry for Refractive Lens Surgery

3 Biometry for Refractive Lens Surgery Mark Packer, I. Howard Fine, Richard S. Hoffman CORE MESSAGES 2 Achieving emmetropia in refractive lens surgery depends on accurate biometry and IOL power calculation.

### Informed Consent for Refractive Lens Exchange (Clear Lens Replacement)

Mark Packer, M.D. Informed Consent for Refractive Lens Exchange (Clear Lens Replacement) This surgery involves the removal of the natural lens of my eye, even though it is not a cataract. The natural lens

### Effect of Preoperative Keratometric Power on Intraoperative Complications in LASIK in 34,099 Eyes

Effect of Preoperative Keratometric Power on Intraoperative Complications in LASIK in 34,099 Eyes J. Carlos Albelda-Vallés, MD; Clara Martin-Reyes, MD; Francisco Ramos, MD; Jaime Beltran, MD; Fernando

### The Efficacy of Multi-Zone Cross-Cylinder Method for Astigmatism Correction

Korean J Ophthalmol Vol. 18:29-34, 2004 The Efficacy of Multi-Zone Cross-Cylinder Method for Astigmatism Correction Seong Joo Shin, MD, Hae Young Lee, MD Department of Ophthalmology, Seoul Adventist Hospital,

### Conductive keratoplasty (CK) utilizes radiofrequency energy. Original Article

Original Article Comparing the Rate of Regression after Conductive Keratoplasty with or without Prior Laser-Assisted in situ Keratomileusis or Photorefractive Keratectomy Majid Moshirfar, Erik Anderson

### Wavefront technology has been used in our

Wavefront Customized Ablations With the WASCA Asclepion Workstation Sophia I. Panagopoulou, BSc; Ioannis G. Pallikaris, MD ABSTRACT PURPOSE: WASCA (Wavefront Aberration Supported Cornea Ablation) is a

### Intraocular lens (IOL) power calculations for cataract

Intraocular lens power calculation after incisional and thermal keratorefractive surgery Mark Packer, MD, Laurie K. Brown, COMT, COE, Richard S. Hoffman, MD, I. Howard Fine, MD Purpose: To evaluate the

### IOL Power Calculations for Postrefractive Surgery Eyes

eyetube.net The Creator s Forum: IOL Power Calculations for Postrefractive Surgery Eyes Olsen Formula By Thomas Olsen, MD, PhD The calculation of IOL power in an eye that has undergone corneal refractive

### Long-Term Outcomes of Flap Amputation After LASIK

Long-Term Outcomes of Flap Amputation After LASIK Priyanka Chhadva BS, Florence Cabot MD, Anat Galor MD, Sonia H. Yoo MD Bascom Palmer Eye Institute, University of Miami Miller School of Medicine Miami

### THE BEST OF BOTH WORLDS Dual-Scheimpflug and Placido Reaching a new level in refractive screening

THE BEST OF BOTH WORLDS Dual-Scheimpflug and Placido Reaching a new level in refractive screening GALILEI G4 Clinical Applications Corneal Implant Planning The comes with a licensable corneal inlay software

### Anterior Elevation Maps as the Screening Test for the Ablation Power of Previous Myopic Refractive Surgery

Anterior Elevation Maps as the Screening Test for the Ablation Power of Previous Myopic Refractive Surgery Soo Yong Jeong, MD, Hee-Seung Chin, MD, PhD, Jung Hyub Oh, MD, PhD Department of Ophthalmology,

### Refractive Surprises In Post Radial Keratotomy Cataract Surgery And Review Of Literature To Calculate Lens Power In Post Refractive Surgery Cases

Refractive Surprises In Post Radial Keratotomy Cataract Surgery And Review Of Literature To Calculate Lens Power In Post Refractive Surgery Cases Dr. Devdatt. S Raut, MBBS. Dr. Suresh Ramchandani, MS.,DNB.,DOMS,.

### Mark E Johnston MD FRCSC www.nebraskaeye.com www.markjohnston.yourmd.com

EBRASKA LASER EYE ASSOCIAT Mark E Johnston MD FRCSC www.nebraskaeye.com www.markjohnston.yourmd.com Pseudoexfoliation Selective laser trabeculoplasty Foldable Acrylic 1995 Intraocular pressure after

### FIRST EXPERIENCE WITH THE ZEISS FEMTOSECOND SYSTEM IN CONJUNC- TION WITH THE MEL 80 IN THE US

FIRST EXPERIENCE WITH THE ZEISS FEMTOSECOND SYSTEM IN CONJUNC- TION WITH THE MEL 80 IN THE US JON DISHLER, MD DENVER, COLORADO, USA INTRODUCTION AND STUDY OBJECTIVES This article summarizes the first US

### Customized corneal ablation and super vision. Customized Corneal Ablation and Super Vision

Customized Corneal Ablation and Super Vision Scott M. MacRae, MD; James Schwiegerling, PhD; Robert Snyder, MD, PhD ABSTRACT PURPOSE: To review the early development of new technologies that are becoming

### Intraocular lens power calculation after myopic excimer laser surgery with no previous data

UPDATE/REVIEW Intraocular lens power calculation after myopic excimer laser surgery with no previous data Juan Carlos Mesa-Gutiérrez, MD, PhD, FEBO; Antonio Rouras-López, MD; Isabel Cabiró-Badimón, MD;

### How do we use the Galilei for cataract and refractive surgery?

How do we use the Galilei for cataract and refractive surgery? Douglas D. Koch, MD Mariko Shirayama, MD* Li Wang, MD, PhD* Mitchell P. Weikert, MD Cullen Eye Institute Baylor College of Medicine Houston,

### Surface Ablation After Corneal

Surface Ablation After Corneal Surgery: Management of Haze Helen K. Wu, MD New England Eye Center Tufts University School of Medicine Boston, MA Financial Disclosures Travel Stipend/Honoraries: IOP Ophthalmics

### OCT-based IOL power calculation for eyes with previous myopic and hyperopic laser vision correction

American Academy of Ophthalmology Annual Meeting Orlando, Florida, 21-25 October 2011 OCT-based IOL power calculation for eyes with previous myopic and hyperopic laser vision correction Weeks Professor

### Our Commitment To You

SYSTEM SUPPORT Quality-crafted, the system boasts dependability with high efficiency and low gas usage. We provide responsive service and maintenance contract options, supported by our nationwide direct

### Long-term stability of the posterior cornea after laser in situ keratomileusis

ARTICLE Long-term stability of the posterior cornea after laser in situ keratomileusis Joseph B. Ciolino, MD, Stephen S. Khachikian, MD, Michael J. Cortese, OD, Michael W. Belin, MD PURPOSE: To study long-term

### REFRACTIVE ERROR AND SURGERIES IN THE UNITED STATES

Introduction REFRACTIVE ERROR AND SURGERIES IN THE UNITED STATES 150 million wear eyeglasses or contact lenses 2.3 million refractive surgeries performed between 1995 and 2001 Introduction REFRACTIVE SURGERY:

### WHAT IS A CATARACT, AND HOW IS IT TREATED?

4089 TAMIAMI TRAIL NORTH SUITE A103 NAPLES, FL 34103 TELEPHONE (239) 262-2020 FAX (239) 435-1084 DOES THE PATIENT NEED OR WANT A TRANSLATOR, INTERPRETOR OR READER? YES NO TO THE PATIENT: You have the right,

### Informed Consent for Refractive Lens Exchange (Clear Lens Extraction)

Informed Consent for Refractive Lens Exchange (Clear Lens Extraction) This form is designed to ensure that you have all the information you need to make a decision about whether or not you wish to undergo

### Management of Corneal Astigmatism by Limbal Relaxing Incisions during Cataract Surgery

Management of Corneal Astigmatism by Limbal Relaxing Incisions during Cataract Surgery Mohammad Ali Zare, MD 1 Mehdi Hosseini Tehrani, MD 2 Mohsen Gohari, MD 3 Mahmood Jabbarvand, MD 1 Mohammad Naser Hashemian,

### Refractive Surgery. Common Refractive Errors

Refractive Surgery Over the last 25 years developments in medical technology and Refractive Surgery allow almost all need for glasses and contact lenses to be eliminated. Currently there are a number of

### Validation of a New Scoring System for the Detection of Early Forme of Keratoconus

10.5005/jp-journals-10025-1019 Alain Saad, Damien Gatinel ORIGINAL ARTICLE Validation of a New Scoring System for the Detection of Early Forme of Keratoconus Alain Saad, Damien Gatinel ABSTRACT Purpose:

### Incision along Steep Axis

Toric IOL An option or a must? ~ 15% cataract surgical patients >1.5 D Options: spectacles, CLs, Incision along steep axis, LRI, AK, toric IOL, Excimer Laser or a combination Walter J. Stark, MD Professor

### RELEX SMILE AND SMILE EXTRA.. OUR 1 YEAR RESULTS AND PATIENTS SURVEY

RELEX SMILE AND SMILE EXTRA.. OUR 1 YEAR RESULTS AND PATIENTS SURVEY DR SANDIP MITRA MD FRCS CORNEA AND REFRACTIVE FELLOW (ROYAL VICTORIA EYE AND EAR HOSPITAL, AUSTRALIA) RELEX SMILE UNIT AT THE ALZAHRA

### One of the exciting new research areas in laser

Future Challenges to Aberration-free Ablative Procedures Cynthia Roberts, PhD One of the exciting new research areas in laser refractive surgery is the development of sophisticated devices to measure the

### refractive surgery a closer look

2011-2012 refractive surgery a closer look How the eye works Light rays enter the eye through the clear cornea, pupil and lens. These light rays are focused directly onto the retina, the light-sensitive

### VISX Wavefront-Guided LASIK for Correction of Myopic Astigmatism, Hyperopic Astigmatism and Mixed Astigmatism (CustomVue LASIK Laser Treatment)

CustomVue Advantage Patient Information Sheet VISX Wavefront-Guided LASIK for Correction of Myopic Astigmatism, Hyperopic Astigmatism and Mixed Astigmatism (CustomVue LASIK Laser Treatment) Statements

### Bitoric Laser In Situ Keratomileusis for the Correction of Simple Myopic and Mixed Astigmatism

Bitoric Laser In Situ Keratomileusis for the Correction of Simple Myopic and Mixed Astigmatism Arturo S. Chayet, MD, 1 Miguel Montes, MD, 1 Laura Gómez, MD, 1 Xavier Rodríguez, MD, 1 Nora Robledo, OD,

### Use of Nepafenac in Lasek Johnny L. Gayton, MD

Use of Nepafenac in Lasek Johnny L. Gayton, MD Kathrine Jackson, COA Eyesight Associates, Warner Robins, GA Analgesic Effect NSAIDs provide analgesic effect 1-3 Minimize pain and discomfort following cataract

### Premium Lenses in Problematic Patients

Premium Lenses in Problematic Patients How to be successful with presbyopic lenses in eyes that have already had LASIK surgery. Walter Bethke, Managing Editor If implanting a monofocal intraocular lens

### AcrySof IQ Toric IOL (SN6ATT) Surgeon Keys for Success & Acknowledgement

AcrySof IQ Toric IOL (SN6ATT) Surgeon Keys for Success & Acknowledgement Alcon Laboratories, Inc is pleased to announce the availability of the AcrySof IQ Toric intraocular lens, and delighted that you

### LASIK. Complications. Customized Ablations. Photorefractive Keratectomy. Femtosecond Keratome for LASIK. Cornea Resculpted

Refractive Surgery: Which Procedure for Which Patient? David R. Hardten, M.D. Minneapolis, Minnesota Have done research, consulting, or speaking for: Alcon, Allergan, AMO, Bausch & Lomb, Inspire, Medtronic,

### Insert to. January 2011. Comfort and confidence for all IOL calculations

Insert to January 2011 Comfort and confidence for all IOL calculations Advanced Optical Biometry and Keratometry with LENSTAR LS 900 CONTENTS Lenstar and Ray-Tracing Calculations...3 By Jaime Aramberri,

### Surgical Advances in Keratoconus. Keratoconus. Innovations in Ophthalmology. New Surgical Advances. Diagnosis of Keratoconus. Scheimpflug imaging

Surgical Advances in Keratoconus Keratoconus Ectatic disorder 1 in 1,000 individuals Starts in adolescence & early adulthood Uncertain cause 20% require corneal transplant Innovations in Ophthalmology

### Management of Unpredictable Post-PRK Corneal Ectasia with Intacs Implantation

Management of Unpredictable Post-PRK Corneal Ectasia with Intacs Implantation Mohammad Naser Hashemian, MD 1 Mahdi AliZadeh, MD 2 Hassan Hashemi, MD 1,3 Firoozeh Rahimi, MD 4 Abstract Purpose: To present

### Keratorefractive Surgery for Post-Cataract Refractive Surprise. Moataz El Sawy

Keratorefractive Surgery for Post-Cataract Refractive Surprise Moataz El Sawy Departmentof Ophthalmology, Faculty of Medicine,MenoufiyaUniversity, Egypt mfelsawy@yahoo.co.uk Abstract: Purpose: To evaluate

### LASER VISION C ORRECTION REFRACTIVE SURGERY CENTER

LASER VISION C ORRECTION REFRACTIVE SURGERY CENTER W e l c o m e Throughout our history, physicians at Mass. Eye and Ear have led clinical advances and research that have resulted in the discovery of disease-causing

### ALTERNATIVES TO LASIK

EYE PHYSICIANS OF NORTH HOUSTON 845 FM 1960 WEST, SUITE 101, Houston, TX 77090 Office: 281 893 1760 Fax: 281 893 4037 INFORMED CONSENT FOR LASER IN-SITU KERATOMILEUSIS (LASIK) INTRODUCTION This information

### Phacoemulsification: Considerations for Astigmatism Management Jason P. Brinton, MD and Thomas A. Oetting, MS, MD June 10, 2011

Phacoemulsification: Considerations for Astigmatism Management Jason P. Brinton, MD and Thomas A. Oetting, MS, MD June 10, 2011 Introduction Patient expectations for cataract surgery have increased significantly

### Outcome of Laser in Situ Keratomeliusis (Lasik) in Low to High Myopia: Review of 200 Cases

Original Article Outcome of Laser in Situ Keratomeliusis (Lasik) in Low to High Myopia: Review of 200 Cases Muhammad Saeed Iqbal, Adil Salim Jafri, P.S. Mahar Pak J Ophthalmol 2008, Vol. 24 No. 3...............................................................................

1 BoydVision TABLE OF CONTENTS: LASER EYE SURGERY CONSENT FORM Risks and Side Effects... 2 Risks Specific to PRK... 3 Risks Specific to LASIK... 4 Patient Statement of Consent... 5 Consent for Laser Eye

### Pre-Operative Laser Surgery Information

Pre-Operative Laser Surgery Information Contact 1800 10 20 20 Our Facility The Canberra Eye Laser Centre has always been at the forefront of refractive technology employing the most up to date equipment

### Tamer O. Gamaly, FRCS; Alaa El Danasoury, MD, FRCS; Akef El Maghraby, MD

A Prospective, Randomized, Contralateral Eye Comparison of Epithelial Laser in situ Keratomileusis and Photorefractive Keratectomy in Eyes Prone to Haze Tamer O. Gamaly, FRCS; Alaa El Danasoury, MD, FRCS;

### ABLATION-RELATED COMPLICATIONS FOLLOWING

Topographically Supported Customized Ablation for the Management of Decentered Laser In Situ Keratomileusis GEORGE D. KYMIONIS, MD, PHD, SOPHIA I. PANAGOPOULOU, BSC, IOANNIS M. ASLANIDES, MD, PHD, SOTIRIS

### Correction of High Astigmatism: Case Studies Using the Mixed-cylinder Approach

Correction of High Astigmatism: Case Studies Using the Mixed-cylinder Approach Hamza N. Khan, MD, MPH, FRCSC; Geoffrey B. Kaye, MBChB, FCS(SA), FRCSC; Jean Luc Febbraro, MD ABSTRACT PURPOSE: To explain

### Cataract Testing. What a Patient undergoes prior to surgery

Cataract Testing What a Patient undergoes prior to surgery FINANCIAL DISCLOSURE I have no financial interest or relationships to disclose What do most Technicians find to be the most mundane yet very important

### All surgical procedures have the potential for

Laser in situ Keratomileusis Retreatment for Residual Myopia and Astigmatism Khaled M. Rashad, MD ABSTRACT PURPOSE: To evaluate the visual and refractive results of laser in situ keratomileusis (LASIK)

### Informed Consent for Refractive Lens Exchange (Clear Lens Replacement)

Drs. Fine, Hoffman and Packer, LLC PHYSICIANS AND SURGEONS, EyeMDs OPHTHALMOLOGY I. Howard Fine, M.D. Richard S. Hoffman, M.D. Mark Packer, M.D. 1550 Oak Street, Suite 5 www.finemd.com Eugene, OR 97401-7701

### Topographically-guided Laser In Situ Keratomileusis to Treat Corneal Irregularities

Topographically-guided Laser In Situ Keratomileusis to Treat Corneal Irregularities Michael C. Knorz, MD, Bettina Jendritza, MD Objective: To evaluate the predictability and safety of topographically guided

### Posterior Corneal Astigmatism: Is It Important? MP Weikert, MD Baylor College of Medicine October 23, 2011

: Is It Important? MP Weikert, MD Baylor College of Medicine October 23, 2011 Corneal Imaging What major challenge do we face when imaging the cornea? Measuring the curvature & refractive power of the

### Update on Post- Refractive Surgery IOL Calculations

Update on Post- Refractive Surgery IOL Calculations Hawaiian Eye 2014 Kauai Rhonda G Waldron MMSc, COMT, CRA, ROUB, RDMS Diagnostic Echographer, Senior Associate in Ophthalmology Emory Eye Center Atlanta,GA

### Post LASIK Ectasia. Examination: Gina M. Rogers, MD and Kenneth M. Goins, MD

Post LASIK Ectasia Gina M. Rogers, MD and Kenneth M. Goins, MD October 6, 2012 Chief Complaint: Decreasing vision after laser- assisted in- situ keratomileusis (LASIK) History of Present Illness: This

### Keratoconus Detection Using Corneal Topography

Keratoconus Detection Using Corneal Topography Jack T. Holladay, MD, MSEE, FACS ABSTRACT PURPOSE: To review the topographic patterns associated with keratoconus suspects and provide criteria for keratoconus

### Comparison Combined LASIK Procedure for Ametropic Presbyopes and Planned Dual Interface for Post-LASIK Presbyopes Using Small Aperture Corneal Inlay

Comparison Combined LASIK Procedure for Ametropic Presbyopes and Planned Dual Interface for Post-LASIK Presbyopes Using Small Aperture Corneal Inlay Minoru Tomita, MD, PhD 1,2 1) Shinagawa LASIK, Tokyo,

### Refractive Errors. Refractive Surgery. Eye Care In Modern Life. Structure of the Eye. Structure of the Eye. Structure of the Eye. Structure of the Eye

Structure of the Eye Eye Care In Modern Life Dr. Dorothy Fan Department of Ophthalmology & Visual Sciences September 2007 Information age > 90% of sensory input Blindness is one of the most fearful disabilities

### Congratulations! You have just joined the thousands of people who are enjoying the benefits of laser vision correction.

Dear Valued Patient, Thank you for choosing Shady Grove Ophthalmology for your laser vision correction procedure. Our excellent staff is committed to offering you the highest quality eye care using state

### Eye Care In Modern Life

Eye Care In Modern Life Dr. Dorothy Fan Department of Ophthalmology & Visual Sciences November 2009 dorothyfan@cuhk.edu.hk Structure of the Eye Information age > 90% of sensory input Blindness is one of

### BESSt 2.0 IOL Power Calculator - REFERENCE GUIDE

BESSt 2.0 IOL Power Calculator - REFERENCE GUIDE Introduction BESSt 2.0 IOL Power Calculator was designed to allow more accurate corneal and IOL power estimation in eyes needing either cataract or clear