LASIK in the Presbyopic Age Group

LASIK in the Presbyopic Age Group Safety, Efficacy, and Predictability in 40- to 69-Year-Old Patients Ramon C. Ghanem, MD, 1,2 Jose de la Cruz, MD, 1,2 Faisal M. Tobaigy, MD, 1 Leonard P. K. Ang, FRCS(Ed), MRCOphth, 1 Dimitri T. Azar, MD 1,2 Objective: To report the safety, efficacy, and predictability of LASIK in a presbyopic population and to examine possible differences between age groups. Design: Retrospective, descriptive, comparative consecutive case series. Participants: Seven hundred ten eyes of 424 patients between 40 and 69 years of age who underwent LASIK by the same surgeon between January 1999 and September 2005. Patients had manifest refractive spherical errors ranging from 10.5 to 6 diopters (D) and cylinder of up to 2.50 D. Methods: LASIK was performed with IntraLase femtosecond laser or Hansatome microkeratomes and VISX Star (S4 or S2; VISX Inc., Santa Clara, CA) or Baush & Lomb Technolas 217z (Zyoptix or PlanoScan; Bausch & Lomb, Claremont, CA) excimer lasers. There were 511 myopic eyes (spherical equivalent [SE], 5.03 2.02 D) and 199 hyperopic eyes (SE, 2.21 1.21 D). Patients were divided into 3 groups: group 1 (40 to 49 years old; n 359 eyes), group 2 (50 to 59 years old; n 293 eyes), and group 3 (60 to 69 years old; n 58 eyes). Main Outcome Measures: Uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), retreatment rates, safety, efficacy, and predictability. Results: The mean age of patients in groups 1, 2, and 3 was 45, 53, and 63 years, respectively. With increasing age, there was a trend toward higher retreatment rates and more myopic end points. Safety, efficacy, and predictability were comparable between all groups. At the final follow-up (mean standard deviation, 10.4 7.4 months), 80% to 100% of eyes had 20/30 or better UCVA and 81% to 90% were within 1.00 D. No eyes lost more than 2 lines of BSCVA, and only 9 eyes (1.3%) lost 2 lines. Subgroup analysis of eyes with a follow-up of 12 months or more was performed. The results were compared with those with shorter follow-up. Both subgroups had comparable outcomes; the duration of follow-up did not affect the visual outcomes. Conclusions: Despite a trend toward worse final BSCVA and higher retreatment rates in older patients, a greater risk of visual loss after LASIK was not observed. LASIK for myopia and hyperopia has reasonable safety, efficacy, and predictability profiles in the 40- to 69-year-old presbyopic population. Ophthalmology 2007;114: 1303 1310 2007 by the American Academy of Ophthalmology. Age-related changes in refractive error are the result of anatomic and functional changes in axial length, lens thickness, and lens opalescence. 1 4 In the Beaver Dam Eye Study, the prevalence of hyperopia increased from 22.1% among people aged 43 to 54 years to 50.2% in those aged 55 Originally received: May 27, 2006. Accepted: October 7, 2006. Manuscript no. 2006-530. 1 Department of Ophthalmology, Massachusetts Eye and Ear Infirmary and Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts. 2 Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois. Supported by the National Institutes of Health, Bethesda, Maryland (grant no. EY10101 [DTA]), and a Research to Prevent Blindness (New York, New York) Lew R. Wasserman Merit Award (DTA). The authors do not have a commercial or proprietary interest in the work. Correspondence to Dimitri T. Azar, MD, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 West Taylor Street, Chicago, IL 60612. E-mail: dazar@uic.edu. to 64 years or older, whereas the prevalence of myopia and emmetropia decreased with age, from 42.9% to 25.1% and from 35% to 24.7% among the same age groups, respectively. 1 In the same population, the change in refraction was noted to occur over many decades. The 10-year change in refraction was 0.48, 0.03, and 0.19 diopters (D) for persons 43 to 59, 60 to 69, and 70 or more years of age, respectively. 3 Because of the improved safety and efficacy of corneal refractive surgery, there is an increasing demand for these procedures among presbyopes. Furthermore, presbyopes are often active, productive, and have high expectations from the outcome of their refractive surgical correction. Studies evaluating the visual outcomes of LASIK for myopia and hyperopia in presbyopic patients are limited. Despite the success of LASIK for the management of refractive errors in presbyopia, especially when combined with monovision, 5 8 some studies have reported suboptimal results with LASIK associated with increasing age. 9 15 Higher inci- 2007 by the American Academy of Ophthalmology ISSN 0161-6420/07/$ see front matter Published by Elsevier Inc. doi:10.1016/j.ophtha.2006.10.026 1303

Ophthalmology Volume 114, Number 7, July 2007 dence of final uncorrected visual acuity (UCVA) of less than 20/40, 9 higher retreatment rates, 10 13 decreased satisfaction, and increased night vision complaints 14,15 have been associated with LASIK in advancing age. Herein, we report the results of a retrospective analysis of the efficacy, predictability, and safety of LASIK performed in patients aged between 40 and 69 years. Patients and Methods Study Design We performed a retrospective chart review of 424 consecutive patients (710 eyes) between 40 and 69 years of age who were treated with LASIK in 1 or both eyes. All eyes were operated on by the same surgeon (DTA) between January, 1999, and September, 2005. This study was part of a retrospective review of refractive surgery approved by the Institutional Review Board of the Massachusetts Eye and Ear Infirmary. Patient Selection Patients were included if they were between 40 and 69 years old with a follow-up of at least 2 months, spherical refraction from 10.50 D of myopia to 6.00 D of hyperopia, and refractive cylinder of up to 2.5 D. Only patients treated with VISX Star (S4 or S2; VISX, Inc., Santa Clara, CA) or Baush & Lomb Technolas 217z (Zyoptix or PlanoScan; Bausch & Lomb, Claremont, CA) excimer lasers and IntraLase femtosecond laser (IntraLase Corp., Irvine, CA) or Hansatome microkeratome (Bausch & Lomb) were included. Patients with monovision correction, where 1 eye was treated for near vision, also were included in the study. Patients were excluded if they had previous surgery or an initial best spectacle-corrected visual acuity (BSCVA) of less than 20/30. Patients were divided into 3 groups based on age. Group 1 included patients in the fifth decade (40 to 49 years of age), group 2 included patients in the sixth decade (50 to 59 years of age), and group 3 included patients in the seventh decade (60 to 69 years of age). Groups also were divided into myopia (including myopic astigmatism) and hyperopia (including hyperopic astigmatism) subgroups. Given the limitations of reporting visual acuity data from the final visit, 16 we performed a subgroup analysis of data obtained at time points of 12 months of follow-up or more (mean standard deviation, 18 3 months; n 280). Evaluation Protocol Monovision was discussed with the myopic presbyopes. Myopic patients with refractive errors of 2.50 D or less who were willing to accept monovision correction had only 1 eye operated on, usually the dominant eye, aiming at distance vision (full correction). After surgery, many of these patients had the option of having their other eye operated, knowing that they would need glasses for reading. Presbyopes with myopia of more than 2.50 D or with hyperopia in most cases had both eyes operated on with the choice of having 1 eye treated for near (monovision; near eye aiming at 35 to 50 cm) or for intermediate vision (minimonovision; near eye aiming at 60 to 70 cm), or both eyes treated for distance vision (full correction). The nondominant eye usually was treated for near vision and the dominant eye was treated for distance vision. The initial treatment plan reflected a consensus between the surgeon and the patient regarding the desired outcome. Patient daily activities and preferences were taken into consideration when choosing the amount of intended anisometropia. The age of the patient was one of the determinants of the approximate target refractions in patients who desired residual near vision: 40 to 44 years of age, near eye at 0.50 to 1.00 D; 45 to 48 years of age, near eye at 1.00 to 1.25 D; 49 to 53 years of age, near eye at 1.25 to 1.50 D; and more than 53 years of age, near eye at 1.50 to 1.75 D, respectively. The ocular dominance was identified by the Miles test, whereby the patient extends both arms, brings both hands together to create a small opening, and then with both eyes open views a distant object through the opening. The examiner then alternates covering each eye to determine which is viewing the object (i.e., the dominant eye). 17 Table 1. Patient Demographics (424 Patients, 710 Eyes) Group 1, 40 to 49 Years Group 2, 50 to 59 Years Group 3, 60 to 69 Years No. eyes (% of total) 359 (50.6%) 293 (41.3%) 58 (8.2%) No. patients (% of total) 215 (50.7%) 175 (41.3%) 34 (8.0%) Laterality, n (% of group) Right 185 (51.5%) 153 (52.2%) 28 (48.3%) Left 174 (48.5%) 140 (47.8%) 30 (51.7%) Gender, n (% of group) Males 105 (48.8%) 86 (49.1%) 17 (50.0%) Females 110 (51.2%) 89 (50.9%) 17 (50.0%) Age (yrs) Mean SD 44.68 2.92 53.43 2.65 63.33 2.45 Min max 40 49 50 59 60 69 Follow-up (mos) Mean SD 11.27 8.46 9.35 5.90 10.62 5.97 Min max 2 49 2 35 2 28 3 336 (93.6%) 268 (91.5%) 51 (87.9%) 6 259 (72.1%) 195 (66.6%) 41 (70.7%) 9 206 (57.4%) 156 (53.2%) 36 (62.1%) 12 141 (39.3%) 104 (35.5%) 35 (60.3%) Wave-front guided, n (% of group) 20 (5.6%) 19 (6.5%) 0 (0%) SD standard deviation. 1304

Ghanem et al LASIK in the Presbyopic Age Group Table 2. Preoperative and Postoperative Refractive Data on the 3 Groups Stratified According to Ametropia (n 710 Eyes) Ametropia* Group 1, 40 to 49 Years Group 2, 50 to 59 Years Group 3, 60 to 69 Years Myopia subgroups No. eyes (% of total) 312 (43.9%) 189 (26.5%) 10 (1.4%) Preoperative Mean SE SD 5.10 2.03 4.91 1.98 4.85 2.59 Minimum maximum 11 to 1.13 10 to 1.25 9.75 to 1.25 Mean cylinder SD 0.82 0.62 0.87 0.6 0.60 0.56 Minimum maximum 2.5 to 0 2.5 to 0 1.5 to 0 Postoperative Mean SE SD 0.65 0.61 0.73 0.66 0.95 0.99 Minimum maximum 3.38 to 0.75 3 to 0.75 3.38 to 0 Mean cylinder SD 0.45 0.34 0.48 0.34 0.55 0.37 Minimum maximum 1.75 to 0 1.25 to 0 1 to0 Hyperopia subgroups No. eyes (% of total) 47 (6.6%) 104 (14.6%) 48 (6.7%) Preoperative Mean MRSE SD 2.38 1.43 2.34 1.18 1.79 0.90 Minimum maximum 1 to 5.25 0.13 to 5.63 1 to 3.75 Mean cylinder SD 0.75 0.78 0.66 0.55 0.61 0.50 Minimum maximum 2.5 to 0 2.5 to 0 2.5 to 0 Postoperative Mean MRSE SD 0.09 0.87 0.02 0.85 0.36 0.99 Minimum maximum 2 to 1.75 3.63 to 2.5 3.88 to 1.50 Mean cylinder SD 0.73 0.49 0.61 0.38 0.69 0.43 Minimum maximum 2.25 to 0 1.75 to 0 1.75 to 0 MRSE manifest refractive spherical equivalent; SD standard deviation; SE spherical equivalent. *All values are in diopters. LASIK Procedure and Retreatments For the LASIK procedure, a flap was created with the IntraLase femtosecond laser or Hansatome microkeratome. The flap was reflected and excimer laser ablation of the stromal bed was performed with the VISX Star (S4 or S2) or Bausch & Lomb Technolas 217z (Zyoptix or PlanoScan) laser. The flap was repositioned on the stromal bed and the interface was irrigated with balanced salt solution. After surgery, a combination of steroids and antibiotics was administered for 1 week. The LASIK surgeon-specific nomogram used in this study undercorrects older patients by approximately 2% for every 10 years of age up to the sixth decade. All retreatments were performed by lifting the flap and ablating the stromal bed. Criteria for retreatment included residual, correctable refractive error causing subjective patient dissatisfaction with the uncorrected postoperative vision, as well as a stable postoperative refraction. Predicted residual posterior stromal bed also was considered as a factor in deciding whether to proceed with LASIK enhancement. When monovision was chosen, the target myopia for near vision was determined based on the patient s age and initial refraction. Patient Examinations Data collection included age, gender, ocular dominance, preoperative BSCVA, manifest refraction, unilateral or bilateral treatment, date of surgery, type of laser and microkeratome, and whether treatment was wavefront guided. Postoperative data included date of the last follow-up visit, UCVA, BSCVA, manifest refraction, and need for retreatment. Data Acquisition and Analysis All visual acuity measurements were reported in negative logarithm of minimum angle of resolution units. For patients who did not read all of the letters on a single line correctly, the conversion was made by interpolating between the values of the logarithm of minimum angle of resolution acuity using the fraction of the Table 3. Characteristics of Patients with Intentional Myopic Endpoints (Monovision) Group 1, 40 to 49 Years (n 92 Patients) Group 2, 50 to 59 Years (n 85 Patients) Group 3, 60 to 69 Years (n 18 Patients) Right eye dominance (%) 55 (59.8%) 54 (63.5%) 13 (72.2%) Crossed MV (% of eyes) 17 (18.5%) 13 (15.3%) 1 (5.5%) Mean PO SE in distance-corrected eye 0.42 0.32 0.13 Mean PO SE in near-corrected eye 1.03 1.06 1.24 Needed enhancement (% of eyes) 10 (10.9%) 9 (10.6%) 2 (11.1%) MV monovision; PO postoperative; SE manifest refractive spherical equivalent. 1305

Parameter Table 4. Visual Outcomes and Retreatment Rates in Myopic Patients (n 511) Group 1, 40 to 49 Years Ophthalmology Volume 114, Number 7, July 2007 Group 1 vs. Group 2 Group 2, 50 to 59 Years Group 1 vs. Group 3 Group 3, 60 to 69 Years Group 2 vs. Group 3 Preoperative BSCVA Mean SD 0.005 0.05 0.004 0.008 0.05 NS 0.02 0.05 NS Minimum maximum 0.12 to 0.18 0.12 to 0.24 0 0.14 Mean Snellen acuity* 20/20 20/20 20/21 Postoperative UCVA Mean SD 0.1 0.15 NS 0.12 0.15 NS 0.11 0.08 NS Minimum maximum 0.12 to 1.15 0.12 to 0.63 0.03 0.21 Mean Snellen acuity* 20/25 20/26 20/26 Postoperative BSCVA Mean SD 0.0002 0.05 NS 0.009 0.05 0.03 0.04 0.03 NS Minimum maximum 0.12 to 0.24 0.12 to 0.38 0 0.08 Mean Snellen acuity* 20/20 20/20 20/22 Change in BSCVA Mean SD 0.005 0.06 NS 0.0009 0.06 NS 0.01 0.06 NS Minimum maximum 0.14 to 0.22 0.2 to 0.14 0.12 to 0.08 Retreatment rate, n (%) 56 (17.8%) NS 32 (16.9%) NS 2 (20%) NS BSCVA best spectacle-corrected visual acuity; NS not significant; SD standard deviation; UCVA uncorrected visual acuity. *Snellen acuity converted from logarithm of the minimum angle of resolution units. Without monovision. Independent samples t test. Chi-square test. number of letters correctly read on a visual acuity line, as suggested by Holladay. 18 Eyes treated for near vision (monovision) were excluded from the efficacy and predictability analysis. Data from the final visit were analyzed using SPSS software version 14.0 (SPSS, Inc., Chicago, IL) and are presented in this study. Independent-samples t tests and chi-square tests were applied. A P value of less than 0.05 was considered statistically significant. Results Demographics, Monovision, and Refractive Data A total of 710 eyes of 424 patients aged 40 to 69 years met the inclusion criteria for this study. There were 215 patients in group 1 (359 eyes), 175 patients in group 2 (293 eyes), and 34 patients in Parameter Table 5. Visual Outcomes and Retreatment in Hyperopic Patients (n 199) Group 1, 40 to 49 Years Group 1 vs. Group 2 Group 2, 50 to 59 Years Group 1 vs. Group 3 Group 3, 60 to 69 Years Group 2 vs. Group 3 Preoperative BSCVA Mean SD 0.004 0.06 NS 0.008 0.06 NS 0.003 0.05 NS Minimum maximum 0.12 to 0.14 0.12 to 0.24 0.12 to 0.16 Mean Snellen acuity* 20/20 20/20 20/20 Postoperative UCVA Mean SD 0.14 0.09 NS 0.12 0.15 NS 0.18 0.19 NS Minimum maximum 0 to 0.42 0.12 to 0.54 0 0.88 Mean Snellen acuity* 20/28 20/26 20/30 Postoperative BSCVA Mean SD 0.04 0.06 0.008 0.01 0.061 NS 0.03 0.05 0.016 Minimum maximum 0.12 to 0.28 0.17 to 0.18 0 0.18 Mean Snellen acuity* 20/22 20/20 20/22 Change in BSCVA Mean SD 0.04 0.063 0.001 0.003 0.06 NS 0.03 0.06 0.004 Minimum maximum 0.12 to 0.23 0.17 to 0.17 0.14 to 0.20 Retreatment rate, n (%) 4 (8.5%) NS 12 (11.5%) NS 10 (20.8%) NS BSCVA best spectacle-corrected visual acuity; NS not significant; SD standard deviation; UCVA uncorrected visual acuity. *Snellen acuity converted from logarithm of the minimum angle of resolution. Without monovision. Independent samples t test. Chi-square test. 1306

group 3 (58 eyes). Gender distribution was similar in all groups. The mean age of patients was 45 years in group 1, 53 years in group 2, and 63 years in group 3. Mean follow-up in groups 1, 2, and 3 was 11, 9, and 11 months, respectively. Patient demographics are shown in Table 1. Preoperative and postoperative refractive data in the 3 age groups stratified according to ametropia are shown in Table 2. There was a tendency toward a more myopic end point in group 3 (age range, 60 69 years) compared with other groups in both myopia and hyperopia subgroups. In 195 patients (46%), a myopic end point was intended in 1 eye (monovision), including 43% in group 1, 49% in group 2, and 53% in group 3. The characteristics of patients with intentional myopic end point (monovision) are shown in Table 3. Visual Outcomes and Retreatment Rate Tables 4 and 5 show visual outcomes and retreatment rates stratified according to age groups for myopia and hyperopia, respectively. In hyperopic subgroups, no statistically significant differences were observed in preoperative BSCVA. The differences in postoperative BSCVA between the groups were not clinically significant. An increase in retreatment rates was observed in the hyperopic subgroup with increasing age; however, it was not statistically significant (Table 5). Efficacy The percentages of eyes with postoperative UCVA better than or equal to 20/20, 20/25, 20/30, and 20/40 according to ametropia are shown in Figure 1. Efficacy in the level of 20/30 was comparable between all groups. Predictability The percentages of eyes with postoperative manifest refractive spherical equivalent within 0.50 D and 1.00 D were evaluated in all groups according to ametropia (Fig 2). Ghanem et al LASIK in the Presbyopic Age Group Safety The distribution of the change in BSCVA is shown in Figure 3. In the myopic subgroups, 3 patients (1.0%) lost 2 lines of BSCVA in group 1. No patient lost 2 or more lines in groups 2 and 3. In hyperopic subgroups, patients who lost 2 lines were as follows: 3 patients (6.3%) in group 1, 1 patient (1.0%) in group 2, and 2 patients (4.2%) in group 3. No eyes lost more than 2 lines of BSCVA in any group. Subgroup Analysis of Patients with Follow-up of 12 Months or More Follow-up was 12 months or more in 141 eyes (39.3%), 104 eyes (35.5%), and 35 eyes (60.3%) in groups 1, 2, and 3, respectively. Efficacy, predictability, and safety profiles of this subgroup are described in Table 6. No statistically significant differences were observed comparing this subgroup with the eyes with shorter follow-up. Discussion Patient age has been considered as an important variable affecting the outcomes of various corneal refractive surgical Figure 1. Bar graphs demonstrating efficacy: uncorrected visual acuity after LASIK for (A) myopia (n 364) and (B) hyperopia (n 151) stratified according to age group. Eyes treated for near (monovision) were excluded. procedures, including radial keratotomy and photorefractive keratectomy. 19 Younger patients tend to have a more aggressive healing response, which may contribute to some regression of the effect of treatment. In LASIK, because of the decreased healing response, it is not clear whether age plays a significant role. Derived by linear regression analysis from previous treatments, nomogram adjustments usually are performed according to age to increase the amount of correction in younger patients. As described in Patients and Methods, our LASIK nomogram attempts to prevent overcorrection in patients older than 40 years of age by reducing the amount of treatment. Regardless of the healing process, LASIK correction can be problematic in presbyopic patients. Many presbyopic patients with myopia experience difficulties with near vision after their refractive error is corrected. Before surgery, many of these patients were able to read by taking off their eyeglasses; after surgery, they may find that they are no 1307

Ophthalmology Volume 114, Number 7, July 2007 patients had monovision LASIK in groups 1, 2, and 3, respectively. Five to eighteen percent of our patients had crossed monovision, which happens when the dominant eye is treated for near vision. 5 The rate of enhancement in the monovision-treated patients was approximately 10%, which compares favorably with the overall population in this study. Increased age also has been associated with decreased postoperative UCVA after LASIK. 9 In our study, the efficacy and predictability of LASIK for myopia and hyperopia were similar in all groups. The differences in mean postoperative UCVA were not statistically significant between groups. The postoperative mean manifest refractive spherical equivalent in the myopic and hyperopic subgroups showed that with increasing age, there was a tendency toward undercorrection of the myopia or overcorrection of the hyperopia. Because accommodative amplitude decreases with age, a myopic end point is desirable in older patients. It may also reflect LASIK nomogram adjustments. Figure 2. Bar graphs demonstrating predictability: manifest refraction spherical equivalent after LASIK for (A) myopia (n 364) and (B) hyperopia (n 151) stratified according to age group. Eyes treated for near (monovision) were excluded. D diopters. longer able to do so. Most patients choose to undergo refractive surgery to decrease their dependence on spectacles and therefore are not willing to wear reading glasses after surgery. Monovision has been used as a strategy to compensate for presbyopia by optically correcting one eye for distance vision and the other eye for near vision. This strategy, however, induces anisometropia with a consequent reduction in binocular visual acuity and stereopsis. 20 Thus, patients desiring good bilateral distance UCVA (e.g., professional drivers) are not good candidates for monovision. Patients have to understand that monovision is a compromise that does not restore accommodation but, rather, compensates for its loss and that there are drawbacks involved. When they understand the tradeoff, they are more likely to adapt to, and be happy with, monovision. LASIK monovision has been successful with rates between 86% to 97.8%. 5 8 In our study, 42.8%, 48.5%, and 52.9% of the Figure 3. Bar graphs demonstrating safety: change of best spectaclecorrected visual acuity after LASIK for (A) myopia (n 511) and (B) hyperopia (n 199) stratified according to age group. 1308

Ghanem et al LASIK in the Presbyopic Age Group Table 6. Efficacy, Predictability, and Safety Profiles for Eyes Followed Up for 12 Months or More Compared with Eyes with Less Than 12 Months of Follow-up <12 Months (n 430) >12 Months (n 280) P Value* Efficacy ( 20/30) Group 1 (40 49 yrs) 161 (73.85%) 107 (75.89%) 0.67 Group 2 (50 59 yrs) 141 (74.60%) 69 (66.35%) 0.13 Group 3 (60 69 yrs) 15 (65.22%) 26 (74.29%) 0.46 Predictability ( 0.5 D) Group 1 (40 49 yrs) 114 (52.29%) 71 (50.35%) 0.72 Group 2 (50 59 yrs) 99 (52.38%) 43 (41.35%) 0.07 Group 3 (60 69 yrs) 11 (47.83%) 16 (45.71%) 0.88 Predictability ( 1.0 D) Group 1 (40 49 yrs) 167 (76.61%) 112 (79.43%) 0.53 Group 2 (50 59 yrs) 148 (78.31%) 75 (72.12%) 0.84 Group 3 (60 69 yrs) 17 (73.91%) 25 (71.43%) 0.23 Safety Group 1 (40 49 yrs) 4 (1.83%) 2 (1.42%) 0.76 Group 2 (50 59 yrs) 0 (0%) 1 (0.96%) 0.18 Group 3 (60 69 yrs) 0 (0%) 2 (5.71%) 0.24 BSCVA best spectacle-corrected visual acuity; D diopters; UCVA uncorrected visual acuity. *Chi-square test. Percentage of eyes with UCVA 20/30. Percentage of eyes with spherical equivalent within 0.5 D and within 1 D from emmetropia, respectively. Percentage of eyes with a loss of 2 or more Snellen lines of BSCVA. Some studies showed a higher retreatment rate associated with increasing age. 10 13 In our study, retreatment rates were higher in the seventh decade group compared with others, but the differences were not statistically significant. Besides age, other factors have been associated with higher enhancement rates, namely higher initial corrections, 11 13 residual astigmatism, 10 and history of rigid contact lens use. 13 The inability of older patients to accommodate small residual refractive errors, nomogram variables, healing response, and the higher incidence of refractive shift, nuclear sclerosis, and against-the-rule astigmatism 4 are among the factors that may explain the higher retreatment rates in older patients. Data from our series are limited by the retrospective nature of the study and the relatively heterogeneous sample. We analyzed the outcome of the last follow-up (final visual acuity). Reporting final vision instead of interval outcomes can introduce a potential bias. 16,21 An overestimation of the number of people with good visual acuity outcomes or an underestimation of the number of people with suboptimal visual acuity outcomes can occur when a specific condition may degenerate, with loss of visual acuity, beyond the time that final outcome was obtained. 16 This may occur in older patients with ocular comorbidities. Another limitation is the issue of patient satisfaction, which could not be assessed with accuracy. This is important in those presbyopic myopes who could read without glasses before surgery but may need them after distance correction. The varying lengths of follow-up, the inclusion of patients operated on with different lasers and microkeratomes, and the difficulty in having clear inclusion and exclusion criteria add to the limitations of this study. Despite these limitations, we were able to make certain observations in the myopic and hyperopic subgroups. Our low rate of vision loss is within the range of results presented by the Ophthalmic Technology Assessment Committee of the American Academy of Ophthalmology (average percent of eyes losing 2 or more lines for myopia and astigmatism, 1%; for hyperopia, hyperopic astigmatism, and mixed astigmatism, 1.4%) and Food and Drug Administration results (percent of eyes losing 2 or more lines, 0.61% after year 2000). 22 24 In the myopic subgroups, the change in BSCVA, which reflects mean gain or loss of BSCVA, showed similar results in the 3 groups. Although clinically not significant, there was a trend toward having a slightly worse preoperative and postoperative BSCVA in older patients. Other ocular comorbidities, such as progression of nuclear sclerosis, glaucoma, dry eye, and macular degeneration, also may be present in older patients, which may influence the BSCVA. In the hyperopic subgroups, loss of BSCVA was significant, with a final worse BSCVA in groups 1 and 3 compared with group 2. This is probably the result of factors other than increasing age, because the greatest loss of BSCVA occurred in group 1, the youngest group, where the mean manifest refractive spherical equivalent ( 2.38 D) and cylinder ( 0.75 D) were greatest. Loss of BSCVA after LASIK for hyperopia and hyperopic astigmatism also has been associated with small ablation zones, flaprelated complications resulting from the necessity of larger flaps like free caps and buttonholes, decentered ablations, and others. 23 In conclusion, our study identified the visual and refractive results in an older, presbyopic population and examined possible differences between age groups. Despite a trend toward worse final BSCVA and higher retreatment rates in older patients, a greater risk of visual loss after LASIK was 1309

Ophthalmology Volume 114, Number 7, July 2007 not observed with increasing age. LASIK for myopia and hyperopia has reasonable safety, efficacy, and predictability profiles in the presbyopic age group. References 1. Wang Q, Klein BE, Klein R, Moss SE. Refractive status in the Beaver Dam Eye Study. Invest Ophthalmol Vis Sci 1994;35: 4344 7. 2. Shufelt C, Fraser-Bell S, Ying-Lai M, et al. Refractive error, ocular biometry, and lens opalescence in an adult population: the Los Angeles Latino Eye Study. Invest Ophthalmol Vis Sci 2005;46:4450 60. 3. Lee KE, Klein BE, Klein R, Wong TY. Changes in refraction over 10 years in an adult population: the Beaver Dam Eye Study. Invest Ophthalmol Vis Sci 2002;43:2566 71. 4. Attebo K, Ivers RQ, Mitchell P. Refractive errors in an older population: the Blue Mountains Eye Study. Ophthalmology 1999;106:1066 72. 5. Jain S, Ou R, Azar DT. Monovision outcomes in presbyopic individuals after refractive surgery. Ophthalmology 2001;108: 1430 3. 6. Miranda D, Krueger RR. Monovision laser in situ keratomileusis for pre-presbyopic and presbyopic patients. J Refract Surg 2004;20:325 8. 7. Goldberg DB. Laser in situ keratomileusis monovision. J Cataract Refract Surg 2001;27:1449 55. 8. Reilly CD, Lee WB, Alvarenga L, et al. Surgical monovision and monovision reversal in LASIK. Cornea 2006;25:136 8. 9. Hersh PS, Steinert RF, Brint SF, Summit PRK-LASIK Study Group. Photorefractive keratectomy versus laser in situ keratomileusis: comparison of optical side effects. Ophthalmology 2000;107:925 33. 10. Hersh PS, Fry KL, Bishop DS. Incidence and associations of retreatment after LASIK. Ophthalmology 2003;110:748 54. 11. Hu DJ, Feder RS, Basti S, et al. Predictive formula for calculating the probability of LASIK enhancement. J Cataract Refract Surg 2004;30:363 8. 12. Netto MV, Wilson SE. Flap lift for LASIK retreatment in eyes with myopia. Ophthalmology 2004;111:1362 7. 13. Perlman EM, Reinert SE. Factors influencing the need for enhancement after laser in situ keratomileusis. J Refract Surg 2004;20:783 9. 14. Bailey MD, Mitchell GL, Dhaliwal DK, et al. Patient satisfaction and visual symptoms after laser in situ keratomileusis. Ophthalmology 2003;110:1371 8. 15. Pop M, Payette Y. Risk factors for night vision complaints after LASIK for myopia. Ophthalmology 2004;111:3 10. 16. Jabs DA. Improving the reporting of clinical case series. Am J Ophthalmol 2005;139:900 5. 17. Miles WR. Ocular dominance in human adults. J Gen Psychol 1930;3:412 20. 18. Holladay JT. Visual acuity measurements. J Cataract Refract Surg 2004;30:287 90. 19. Loewenstein A, Lipshitz I, Levanon D, et al. Influence of patient age on photorefractive keratectomy for myopia. J Refract Surg 1997;13:23 6. 20. Jain S, Arora I, Azar DT. Success of monovision in presbyopes: review of the literature and potential applications to refractive surgery. Surv Ophthalmol 1996;40:491 9. 21. DiLoreto DA Jr, Bressler NM, Bressler SB, Schachat AP. Use of best and final visual acuity outcomes in ophthalmological research. Arch Ophthalmol 2003;121:1586 90. 22. Sugar A, Rapuano CJ, Culbertson WW, et al. Laser in situ keratomileusis for myopia and astigmatism: safety and efficacy. A report by the American Academy of Ophthalmology. Ophthalmology 2002;109:175 87. 23. Varley GA, Huang D, Rapuano CJ, et al. LASIK for hyperopia, hyperopic astigmatism, and mixed astigmatism. A report by the American Academy of Ophthalmology. Ophthalmology 2004;111:1604 17. 24. Watson SL, Bunce C, Allan BD. Improved safety in contemporary LASIK. Ophthalmology 2005;112:1375 80. 1310