Refractive changes following cataract surgery: the Blue Mountains Eye Study

This study aimed to assess refractive changes following cataract surgery in subjects attending the Blue Mountains Eye Study baseline examinations in 1992-1994 (3654 residents aged 49+ years),with 2335 (75.1%) survivors re-examined after 5 years. Participants underwent a standardized subjective refraction. History of cataract surgery was confirmed at examination and lens photograph grading. During follow up, 151 persons had cataract surgery (60 bilateral, 91 unilateral). After exclusions, data from 198 eyes(93 right, 105 left) were analysed. The proportions of eyes achieving postoperative spherical equivalent refraction (SER) -0.25 to +0.25 D, -0.50 to +0.50 D, -0.75 to +0.75 D and -1.00 to +1.00 D,were 32%, 44%, 60% and 74%,respectively. The magnitude and direction of refractive changes following cataract surgery were related to the preoperative refraction. Myopic eyes had a hyperopic shift (mean +2.76 D),hyperopic eyes a myopic shift (mean -1.77 D) and emmetropic eyes recorded little change (mean -0.13 D). Astigmatism (> or = 1.00 D cylinder) increased slightly postoperatively, from 47% to 56%, mostly 'against the rule' but with less oblique astigmatism. These findings indicate satisfactory refractive outcomes following current cataract surgery in a random older population.     

Changes in refraction over 10 years in an adult population: the Beaver Dam Eye study

PURPOSE: To quantify the 10-year change in refraction in persons more than 40 years of age. METHODS: All people 43 to 84 years of age and living in Beaver Dam, Wisconsin, in 1988 were invited for a baseline examination (1988-1990), a 5-year follow-up examination (1993-1995), and a 10-year follow-up examination (1998-2000). Refractions were determined according to the same protocol at all examinations. Aphakic and pseudophakic eyes and eyes with best corrected visual acuity of 20/200 or worse were excluded. After exclusions, refraction data were available on 2362 right eyes of the 2937 people examined at baseline and 10-year follow-up. RESULTS: Age was related to the direction and amount of change in refraction. Spherical equivalent became more positive in the youngest subjects and more negative in the oldest. After adjustment for the severity of nuclear sclerosis and other factors, the 10-year change in refraction was +0.48, +0.03, and -0.19 D for persons 43 to 59, 60 to 69 and 70+ years of age at the baseline examination, respectively. Severity of nuclear sclerosis was also strongly related to amount of change. Those with mild nuclear sclerosis at baseline had a change of +0.35 D, whereas those with severe nuclear sclerosis had a change of -0.53 D. The amount of change was also related to diabetes and weakly related to baseline refractive error, but was unrelated to gender and education. In addition to the longitudinal changes observed, there was a birth cohort effect. In comparing people of the same age across examinations, those born in more recent years had more myopia than those born in earlier years. CONCLUSIONS: Significant changes in spherical equivalent in adults occur over a 10-year period. Younger people became more hyperopic, whereas older people became more myopic. These data provide evidence of a longitudinal change in refraction in adults, which may explain the refractive patterns observed in cross-sectional studies.     

儿童屈光不正状态的临床分析

目的：了解2～15岁视力低常的儿童屈光不正的分布规律。 方法:对我院2009-04/2010-04视光学门诊2～15岁的1638例3266眼(男725例1446眼,女913例1820眼)视力低常者进行散瞳验光并统计分析。 结果：在3131眼中,男生近视性屈光不正为1056眼,远视性屈光不正317眼,以近视性屈光不正为主,其中以复性近视散光多见,占35.48％。女生近视性屈光不正为1455眼,远视性屈光不正303眼,也以近视性屈光不正为主,其中以复性近视散光多见,占40.71％。散光的分布中男女童均是以复性近视散光为主,复性远视散光次之。顺规散光、逆规散光和斜轴散光的弱视发生率存在显著性差异（P＜0.01）。 结论：随着学习压力的增大儿童长时间看书学习和电脑的使用大大增加了近视性屈光不正发生的概率。逆规散光是弱视发生的重要影响因素,矫正逆规散光可能有利于儿童弱视的治疗。     

Laser in situ keratomileusis for refractive error after cataract surgery

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) to correct refractive error following cataract surgery. SETTING: The Eye Institute, Sydney, Australia. METHODS: This retrospective study reviewed 23 eyes (19 patients; 10 female, 9 male) treated with LASIK for refractive error following cataract surgery. The Summit Apex Plus and Ladarvision excimer laser and the SKBM microkeratome were used. The mean age was 63.5 years (range 50 to 88 years). The mean length of follow-up was 8.4 months (range 1 to 12 months) and mean interval between cataract surgery and LASIK was 12 months (range 2.5 to 46 months). RESULTS: The mean preoperative spherical equivalent refraction (SEQ) for myopic eyes was -3.08 +/- 0.84 diopters (D) (range -4.75 to -2.00 D) and for hyperopic eyes was +1.82 +/- 1.03 D (range +0.75 to +3.00 D). The mean improvement following LASIK surgery was greater for myopic than hyperopic eyes (myopic, 2.54 +/- 1.03 D versus hyperopic, 1.73 +/- 0.62 D; P=.033). The percentage of patients within +/-0.5 D of intended refraction post-LASIK surgery was 83.3% for myopic eyes and 90.9% for hyperopic eyes and all eyes were within +/-1.0 D of intended (P<.001). The percentage of eyes with uncorrected visual acuity of 20/40 or better in the myopic group improved from none preoperatively to 91.7% postoperatively (P<.001) and in the hyperopic group improved from 27.3% preoperatively to 90.9% postoperatively (P=.008). No eyes lost 2 or more lines of best corrected visual acuity. CONCLUSION: Laser in situ keratomileusis appears to be effective in correcting refractive error following cataract surgery. Longer-term studies are required to determine refractive stability.     

The evolution of refractive status in Chinese infants during the first year of life and its affected factors

AIM: To study the evolution of the refractive status and examine the affected factors in infants during the first year of life in a large sample size in China. METHODS: A total of 1258 babies (2516 eyes) aged 32wk gestational age to 1y participated in the study, including 766 premature and 492 full-term infants. First, each baby received an orthoptic examination, slit-lamp checking and fundus imaging. Patients with diseases which might affect refractive status were excluded from the cohort. The cycloplegia retinoscopy was performed. Their neonatal histories were reviewed. Each measurement contained the refractive status and calculation of the spherical equivalent (SE). RESULTS: Refractive state showed an average hyperopia of +0.94±1.63 D at early ages, followed by a trend toward more hyperopia. The refractive state reached the top (+2.43±1.46 D) at the age of one to two months. Then gliding till one year old when the refractive state reached +0.59±1.41 D. The prevalence of astigmatism was 42.17% in the study, being 2.82% myopic astigmatism and 39.35% hyperopic astigmatism. The 94.1% of hyperopic astigmatism was with-the-rule astigmatism and 71.83% of myopic astigmatism was with-the-rule astigmatism. Refractive state between boys and girls was different. The mean SE of boys was +1.97±1.57 D, while that of girls was +1.79±1.46 D, and the difference was significant. CONCLUSION: Before one year old, the change of refractive status is associated with checking age and sex. At the age of one to two months, the degree of hyperopia reaches the top. Boys have more hyperopic degree than girls, and with-the-rule astigmatism is predominant. Excluding premature infants with advanced retinopathy of prematurity, premature and full-term children have same refraction status.     

儿童混合性散光的屈光演变规律

目的 探讨儿童混合性散光的屈光演变规律。方法 选择4～9岁混合性散光儿童38例66眼，每年予1％阿托品扩瞳检影验光1次，连续4年，记录屈光状态，分析其等效球镜、远视、近视屈光度及散光度的动态变化。结果 儿童混合性散光绝大多数为顺规散光，经扩瞳检影、配镜可获得较好的矫正视力，视力〉0．6。随访4年，患儿等效球镜及远视主径线的屈光度逐年降低（P〈0．01），近视主径线的屈光度逐年加深（P〈0．01），散光度及轴位基本保持稳定不变（P〉0．05）。结论 儿童混合性散光可能是儿童屈光系统发育过程中的一个特定阶段，随着儿童年龄的增长，多可演变为近视散光，在儿童期，应密切随访，及时、正确地配镜矫正，以提高乖改善儿童视功能。     

Refractive error change at the United States Air Force Academy--class of 1985

A retrospective study was conducted at the United States Air-Force Academy (USAFA) to determine the incidence and change in refractive error over a 2.5-year period between the entrance and third academic year physical examinations. For all 994 eyes (497 cadets aged 17 to 21 years) at entrance, there were 37.3% hyperopes, 18.5% emmetropes, and 44.2% myopes of -0.25 D or more, by spherical equivalent (SPEQ). A significant (p less than 0.001) mean SPEQ change of -0.18 D, -0.21 D, and -0.57 D occurred for the hyperopic, emmetropic, and myopic eyes, respectively, over this period. A myopic change of -0.25 D or more was seen in 47.7%, 41.3%, and 74.0% of the hyperopic, emmetropic, and myopic eyes, respectively, with a clinically significant myopic shift of -0.50 D or greater seen in 21.3%, 25.0%, and 55.1% of these refractive error types, respectively. Myopia progression was derived separately from those eyes showing any amount of myopic shift (greater than or equal to -0.12 D), and was -0.42 D, -0.52 D, and -0.75 D for the hyperopic, emmetropic, and myopic eyes, respectively. There was a higher incidence and rate of myopia increase in the higher refractive errors, whether hyperopic or myopic. These findings suggest that 17- to 21-year-olds are not as safe from a myopic change as thought previously, particularly during an intensive educational program.     

The progression of refractive error in school-age children: Shunyi district,China

PURPOSE: To assess the progression of refractive error and the incidence of myopia in school-age children in the Shunyi District of Beijing, China. DESIGN: A longitudinal cohort study. METHODS: A population-based sample of 4,662 children initially examined in 1998 at ages 5 to 13 years was reexamined between September and November, 2000. Refractive error was measured under cycloplegia with autorefraction. Age, sex, and baseline refractive error were evaluated as risk factors for progression. RESULTS: In 28.5 months, the average change in refractive error was -0.42 diopters (standard deviation, 0.68) in right eyes. Myopic shift of refractive error was associated with female sex, older age, and higher myopic or hyperopic refractive error at baseline. The average change in astigmatic error was essentially zero, with significant change in both directions more likely among those with higher baseline astigmatism. Findings were similar for left eyes. The cumulative incidence of myopia, defined as a spherical equivalent refractive error of -0.50 diopters or more in either eye, among initial emmetropes and hyperopes was 14.1% (95% confidence interval [CI], 11.8%-16.5%) for male and 23.5% (95% CI, 20.8%-26.1%) for female subjects. Myopia incidence increased sixfold to sevenfold between baseline age 5 and 12, before decreasing at age 13, for both male and female subjects. CONCLUSIONS: In the design of cost-effective programs for the periodic screening and treatment of uncorrected refractive error, children initially found to require refractive correction should be targeted for relatively frequent rescreening, as should girls and older children. Further study is required to better understand environmental and genetic risk factors for myopia development and progression.     

Laser in situ keratomileusis for spherical hyperopia and hyperopic astigmatism using the NIDEK EC-5000 excimer laser

PURPOSE: To assess the efficacy, predictability, and safety of LASIK for the surgical correction of low to moderate hyperopia and hyperopic astigmatism using the NIDEK EC-5000 excimer laser. METHODS: In a multicenter United States Food and Drug Administration (FDA) regulated study of LASIK, 7 centers enrolled 293 eyes with manifest refraction sphere that ranged from +0.50 to +6.00 diopters (D) with or without astigmatism up to 3.00 D. The intended outcome was plano in all eyes. Patients were treated bilaterally. One year postoperative outcomes are reported. RESULTS: The mean spherical equivalent refraction (MRSE) for all eyes changed from +2.61 +/- 1.19 D (range: +0.50 to +6.63 D) preoperatively to +0.35 +/- 0.54 D (range: -1.63 to +2.00 D) 1 year postoperatively. Overall, 61% (170/279) of eyes achieved distance uncorrected visual acuity (UCVA) of 20/20 or better, 82% (228/279) of eyes saw 20/25 or better, and 99% (277/279) of eyes saw 20/40 or better. Refractive accuracy was demonstrated as 63.1% (176/279) of eyes achieved a MRSE within +/- 0.50 D and 90.3% (252/279) of eyes within +/- 1.00 D. Less than 2% (4/279) of eyes lost 2 lines of distance best spectacle-corrected visual acuity. Stability of refraction was demonstrated by 6 months, with a mean hyperopic shift of < 0.03 D from 3 to 6 months. CONCLUSIONS: The NIDEK EC-5000 corrected hyperopia and hyperopic astigmatism with UCVA, refractive accuracy, 1-year stability, and safety that surpassed all FDA criteria.     

阿托品眼膏及环戊通眼液散瞳儿童验光结果对比分析

目的 比较屈光不正儿童使用1%环戊通眼液与1%阿托品眼膏后检影验光结果的差异情况.方法 对226例(452只眼)屈光不正儿童使用环戊通眼液扩瞳后检影验光,48h后用1%阿托品眼膏对相同的患者再行扩瞳检影验光,比较两次验光结果.结果 远视组中两种药扩瞳验光结果球镜差值≤0.5D的眼数占72.2%,球镜差值＞0.5D的眼数为27.8%;阿托品眼膏扩瞳后验光的远视球镜值均高于环戊通眼液扩瞳后验光的结果.随着年龄增加,两种药验光的远视球镜差异值下降,2～5岁组与5～7岁组和7～12岁组比较,球镜差异值均有统计学意义.2～8岁组中近视球镜差值＞0.5D的眼数占9%,8～12岁组中近视球镜差值＞0.5D的占2.7%.混合性散光组中两种药扩瞳验光结果球镜差值＞0.5D的眼数占32%.使用两种药扩瞳后验光,近视和混合性散光组的前、后柱镜差值无统计学意义,而远视组的前、后柱镜差异有统计学意义,但差异＞0.5D的仅为1.8%.结论 1%环戊通眼液扩瞳验光结果与阿托品眼膏扩瞳验光结果比较,主要表现为球镜值的误差,柱镜值误差极小.8岁以上近视儿童首诊验光可使用环戊通作为睫状肌麻痹剂.12岁以下的远视和混合性散光儿童验光应尽量使用1%阿托品眼膏扩瞳.     

阿托品眼膏及环戊通眼液散瞳儿童验光结果对比分析

目的 比较屈光不正儿童使用1%环戊通眼液与1%阿托品眼膏后检影验光结果的差异情况.方法 对226例(452只眼)屈光不正儿童使用环戊通眼液扩瞳后检影验光,48h后用1%阿托品眼膏对相同的患者再行扩瞳检影验光,比较两次验光结果.结果 远视组中两种药扩瞳验光结果球镜差值≤0.5D的眼数占72.2%,球镜差值＞0.5D的眼数为27.8%;阿托品眼膏扩瞳后验光的远视球镜值均高于环戊通眼液扩瞳后验光的结果.随着年龄增加,两种药验光的远视球镜差异值下降,2～5岁组与5～7岁组和7～12岁组比较,球镜差异值均有统计学意义.2～8岁组中近视球镜差值＞0.5D的眼数占9%,8～12岁组中近视球镜差值＞0.5D的占2.7%.混合性散光组中两种药扩瞳验光结果球镜差值＞0.5D的眼数占32%.使用两种药扩瞳后验光,近视和混合性散光组的前、后柱镜差值无统计学意义,而远视组的前、后柱镜差异有统计学意义,但差异＞0.5D的仅为1.8%.结论 1%环戊通眼液扩瞳验光结果与阿托品眼膏扩瞳验光结果比较,主要表现为球镜值的误差,柱镜值误差极小.8岁以上近视儿童首诊验光可使用环戊通作为睫状肌麻痹剂.12岁以下的远视和混合性散光儿童验光应尽量使用1%阿托品眼膏扩瞳.     

Comparison of LADARVision and Visx Star S3 laser in situ keratomileusis outcomes in myopia and hyperopia

PURPOSE: To compare visual outcomes with 2 commonly used excimer lasers, the Autonomous LADARVision (LV) (Alcon Laboratories Inc.) and the Visx Star S3 (S3), in the performance of myopic and hyperopic astigmatic laser in situ keratomileusis (LASIK). SETTING: Zale Lipshy University Hospital Laser Center for Vision, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: In this retrospective single-center 3-surgeon cohort comparison, 100 consecutive LV-treated myopic eyes with a mean manifest refraction spherical equivalent (MRSE) of -3.22 diopters (D) (range 0 to -6.00 D) (mean astigmatism 0.95 D [range 0 to 4.00 D]) were compared with 100 consecutive S3-treated eyes with a similar MRSE (mean MRSE -3.19 D; mean astigmatism 0.66 D [range 0 to 2.75 D]). Forty-one consecutive LV-treated hyperopic eyes with a mean MRSE of +2.59 D (range +1.00 to +6.00 D) (mean astigmatism 0.89 D [range 0 to 3.50 D]) were compared with 25 consecutive S3-treated eyes with a similar MRSE (mean MRSE +2.70 D; mean astigmatism 0.87 D [range 0 to 2.75 D]). The following outcomes were compared: uncorrected visual acuity, refractive predictability and stability, gain or loss of best spectacle-corrected visual acuity, and need for enhancement. RESULTS: Statistically significant differences in outcomes were found between lasers in the treatment of hyperopia and hyperopic astigmatism. No outcome differences between lasers were found in the treatment of myopia and myopic astigmatism. CONCLUSION: The LV and S3 lasers yielded equivalent results in myopic LASIK between 0 and -6.00 D; however, the LADARVision yielded statistically significantly better results in hyperopic LASIK between +1.00 and +6.00 D.     

Topographic and biomechanical differences between hyperopic and myopic laser in situ keratomileusis

PURPOSE: To evaluate the size, shape, and uniformity of the videokeratographic functional optical zone (FOZ) after laser in situ keratomileusis (LASIK) in 2 cohorts of patients with equivalent amounts of preoperative myopic or hyperopic astigmatism. SETTING: Pepose Vision Institute, St. Louis, Missouri, USA. METHODS: Eyes with myopic or hyperopic astigmatism (n=27 in each group) that had LASIK with the Visx Star S3 laser were retrospectively selected to match for level of preoperative refractive error. Slit-scanning videokeratography was performed preoperatively and 6 months postoperatively and analyzed using custom software. The FOZ was calculated by analyzing refractive power maps using a region-growing algorithm. Difference maps were generated from slit images and compared for interval change in corneal elevation, tangential curvature, and refractive power. The difference maps were also averaged (mean difference maps) for each target population. A Zernike decomposition of corneal first-surface elevation was performed to compare postoperative values with baseline parameters. RESULTS: The mean postoperative refractive sphere at 6 months was -0.17 diopter (D) +/- 0.66 (SD) and +0.25 +/- 0.85 D in the myopia group and hyperopia group, respectively, and the mean postoperative astigmatism, -0.49 +/- 0.32 D and -0.65 +/- 0.52 D, respectively (P=.11). Based on the refractive power maps, the mean preoperative and postoperative myopic FOZ was 33.09 +/- 7.30 mm(2) and 30.94 +/- 5.43 mm(2), respectively, and the mean hyperopic FOZ, 33.19 +/- 7.96 mm(2) and 37.99 +/- 6.88 mm(2), respectively. After LASIK, there was an increase in magnitude of negative anterior corneal surface spherical-like Zernike values in the myopia group (P<.0001) and an increase in magnitude of positive spherical-like Zernike values in the hyperopia group. Postoperatively, significant induction of corneal surface horizontal coma was noted in hyperopic eyes (P<.0001). Hyperopic eyes, on average, had larger topographic FOZs after LASIK, but with less uniformity of curvature and power change than myopic eyes. CONCLUSIONS: Hyperopic LASIK, which involves more transition points along the ablation diameter, produced a less uniform topographic FOZ than typical myopic treatments. Less predictable biomechanical changes from the circumferential release of tension on collagen bundles after midperipheral hyperopic ablation and greater variation in beam centration and the angle of incidence may contribute to the greater variability in corneal curvature and power in hyperopic LASIK than in myopic LASIK.     

Refractive errors in a Finnish rural population

Refractive errors in 611 persons living in a rural area were examined. Males numbered 281 and females 330. The age range was from 6 to 85 years. In 73 (11.9%) persons the refraction was myopic (SER less than or equal to 0.5 D) and in 173 (28.3%) hyperopic (SER greater than or equal to + 2 D). Myopia was most frequently detected in persons aged 21-30 years (22.6%), and the proportion of myopia decreased towards both extremes of age. In all age groups females were more myopic than males. In persons aged 21-60 years the most educated proved to have more myopia and less hyperopia than those with less education. In 158 (25.9%) of the eyes, astigmatism was detectable. The degree of astigmatism changed little with advancing age and was independent of sex. In myopic eyes the range of astigmatic error was wider than in hyperopic eyes. The axis of + cylinders was in hyperopic eyes mostly horizontal and in myopic eyes vertical. Anisometropia of 1.25-2.0 D was detected in 24 (4.0%) persons and in 19 (3.1%) persons it was over 2 D.     

Topography-controlled excimer laser photorefractive keratectomy

PURPOSE: To assess whether photorefractive keratectomy (PRK) controlled by videokeratography can successfully treat refractive errors in eyes with corneal irregularities and improve spectacle-corrected visual acuity. METHODS: In a prospective clinical study, PRK was performed in 10 eyes of 10 patients. Reason for surgery was irregular astigmatism after penetrating keratoplasty, corneal irregularity after corneal scarring, corneal astigmatism in keratoconus, and decentration after myopic and hyperopic PRK. Excimer ablation was controlled by preoperative videokeratography (Orbscan II, Orbtek) using the MEL-70 system from Aesculap Meditec. Follow-up was 6 months. RESULTS: Concerning manifest refraction, the sphere was reduced on average from +1.92 to +0.57 D, 6 months postoperatively. Cylinder changed from -1.95 D on average to -0.30 D at 6 months postoperatively. There was improvement of uncorrected visual acuity of 2 or more lines in 5 eyes and no change in 5 eyes 6 months postoperatively. Spectacle-corrected visual acuity improved in 2 eyes by 2 to 3 lines, in 9 eyes by 1 to 3 lines, and showed no change in 1 eye. CONCLUSION: Videokeratography-controlled PRK improved refractive errors in irregular corneas with improvement of spectacle-corrected visual acuity.     

Changes in refractive error over a 5-year interval in the Beaver Dam Eye Study.

PURPOSE: To examine changes in spherical equivalent over a 5-year period in persons 43 to 84 years of age. METHODS: All people 43 to 84 years of age and living in Beaver Dam, Wisconsin, in 1988 were invited for a baseline examination (1988-1990) and a 5-year follow-up examination (1993-1995). Refractions were determined according to the same protocol at both examinations. Aphakic and pseudophakic eyes were excluded as well as eyes with best corrected Snellen visual acuity of 20/40 and worse. After exclusions, refraction was obtained on 3007 right eyes and 3012 left eyes of the 3684 people participating in both examinations. RESULTS: Right and left eyes behaved similarly. Spherical equivalent became more positive in the youngest subjects and more negative in older subjects. After adjusting for other factors, the 5-year change in spherical equivalent of those 45, 55, 65, and 75 years of age was +0.15, +0.18, +0.10, and -0.07D, respectively. Severity of nuclear sclerosis was related to the amount of change. Those with mild nuclear sclerosis at baseline had a change of +0.2 D, whereas those with severe nuclear sclerosis had a change of -0.5 D. The amount of change was also related to gender, diabetes, and age at onset of myopia. It was unrelated to education and baseline spherical equivalent. CONCLUSIONS: Changes in spherical equivalent over a 5-year period were small. Before the age of 70, people became more hyperopic. After the age of 70, people became more myopic. Much of the myopic change may be related to increasing nuclear sclerosis.     

Results of photorefractive keratectomy for hyperopia using the VISX star excimer laser system

PURPOSE: To evaluate safety, efficacy, and predictability of photorefractive keratectomy (PRK) for hyperopic astigmatism of +1.75 to 00 D manifest refractive sphere and up to -2.50 D manifest refractive astigmatism using the VISX Star excimer laser system, version 2.5 software. METHODS: Treatment was performed on 32 eyes of 21 patients. Eighteen of 21 patients were 45 years of age or older. Manifest and cycloplegic refraction together with Pelli-Robson contrast sensitivity assessment was performed prior to surgery and 1, 3, 6, 12, and 24 months after treatment. RESULTS: Twenty-seven of 32 surgical procedures were reviewed 1 year after treatment (84%). Corneal epithelial healing was complete between day 4 and 10. Twelve months after treatment, 25 of 27 eyes (93%) achieved 20/40 or better uncorrected visual acuity and 19 eyes (70%) achieved 20/20. No patient lost two or more lines of Snellen visual acuity assessed 6 months and later after treatment. The mean spherical equivalent refraction was reduced from +2.90 at baseline to +0.10 D at 1 year and +0.40 D at 2 years; 65% of eyes had a refraction within +/- 0.50 D. Four patients had further treatment by laser in situ keratomileusis for undercorrection in three eyes and overcorrection in one eye. Pelli-Robson contrast acuity was significantly reduced 12 months after treatment from a mean 1.72 before to 1.66 after PRK (P = .02, t-test). CONCLUSIONS: PRK for hyperopia using the VISX Star excimer laser system was effective in the treatment of hyperopic astigmatism. Although no patient lost two or more lines of high contrast best spectacle-corrected Snellen visual acuity 1 year after treatment, there was a significant decrease in Pelli-Robson contrast acuity.     

Surgically induced astigmatism after hyperopic and myopic photorefractive keratectomy

PURPOSE: To compare the axis and magnitude of surgically induced refractive astigmatism (SIA) after hyperopic and myopic photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: In this single-center retrospective study, the VISX Star S2 excimer laser was used to create a peripheral annular ablation profile to correct spherical hyperopia in 23 eyes of 16 consecutive patients. Attempted corrections ranged from +0.50 diopter (D) to +4.25 D with 0 to 1.00 D of astigmatism. The same laser was used to create a central ablation profile to correct spherical myopia in 25 eyes of 17 consecutive patients. Attempted corrections ranged from -2.25 to -6.50 D with 0 to 1.00 D of astigmatism. The absolute change in refractive astigmatism was calculated by taking the difference in magnitudes of astigmatism before and after laser treatment without regard to axis. Axis and magnitude of SIA were analyzed by vector differences. Magnitudes were compared using the Student t test, and axial shifts were compared using the chi-square test. All patients were followed for a minimum of 6 months. RESULTS: The mean changes in absolute astigmatism were 0.29 +/- 0.28 D at 3 months and 0.34 +/- 0.29 D at 6 months after hyperopic PRK and 0.40 +/- 0.35 D at 3 months and 0.39 +/- 0.36 D at 6 months after myopic PRK. The mean vectoral magnitudes were 0.49 +/- 0.29 at 3 months and 0.52 +/- 0.25 at 6 months after hyperopic PRK and 0.48 +/- 0.39 at 3 months and 0.44 +/- 0.38 at 6 months after myopic PRK. The mean values for SIA (the centroid) were 0.10 +/- 0.57 D x 113 degrees at 3 months and 0.15 +/- 0.57 D x 131 degrees at 6 months after hyperopic PRK and 0.04 +/- 0.63 D x 160 degrees at 3 months and 0.08 +/- 0.58 D x 171 degrees at 6 months after myopic PRK. There was no statistically significant difference between the 2 groups in vectoral axis or magnitude of SIA. CONCLUSION: Surgically induced astigmatism after hyperopic PRK was comparable to astigmatism induced by myopic PRK. A peripheral annular ablation for hyperopic correction, similar to a central ablation in myopic PRK, did not appear to result in uneven corneal healing causing astigmatism.     

高龄老年人472眼屈光状态的临床分析

目的:探讨高龄老年人眼视力状况及屈光分布,做好高龄老年人的视力保健。方法:标准照明下查70岁以上高龄老年人472眼远视力,作仔细的眼部和屈光状态的检查并矫正其视力。结果:全组472眼中屈光不正468眼(99.2%),全组以近视居多,且随着年龄递增,近视所占比例逐渐增大。散光415眼(87.9%),70～80岁组以远视散光为主,80岁以上则以近视散光为主,全组散光以近视性逆规散光眼所占比例最大,共172眼(36.4%),远视散光眼散光度数集中在0.50～1.00D,近视散光和混合性散光眼度数集中在1.25～2.00D。全组裸眼视力随年龄增加而降低,各年龄组矫正视力均有明显提高。结论:高龄老年人由于眼睑和晶状体等的老年性改变,其屈光状态向近视性逆规散光发展,成为影响其视力的主要原因,尚未行白内障摘除之高龄老年人,定期检查其屈光状态并做必要的屈光矫正能明显提高高龄老年人的视力。     

Off-axis refraction and aberrations following conventional laser in situ keratomileusis

PURPOSE: To investigate off-axis refraction and aberrations following conventional laser in situ keratomileusis (LASIK) for myopia and hypermetropia. SETTING: School of Optometry, Queensland University of Technology, Australia. METHODS: Using an autorefractor, off-axis refractions were analyzed along the horizontal visual field between 35 degrees nasally and 35 degrees temporally in 1 eye each of 15 emmetropic subjects (-0.50 to +0.50 diopters [D]), 6 myopic subjects (-2.25 to -6.50 D), 6 hyperopic subjects (+1.50 to +3.00 D), 6 myopic LASIK patients (presurgical refraction -2.75 to -9.00 D), and 6 hyperopic LASIK patients (presurgical refraction +0.75 to +2.00 D). Wavefront sensing measured off-axis higher-order aberrations in 2 myopic LASIK patients. RESULTS: In myopic LASIK, the mean spherical components of refraction M became highly myopic away from the center of the visual field; in emmetropic and untreated myopic eyes, there were relatively small myopic shifts and hyperopic shifts, respectively. Off-axis 90-degree to 180-degree astigmatisms J180 in myopic LASIK subjects were greater than in untreated subjects. In hyperopic LASIK, there were mainly hyperopic shifts in M, opposite the direction in emmetropic and untreated hyperopic subjects. Off-axis J180 was less than in emmetropic and untreated hyperopic subjects. Some hyperopic LASIK patients had greater off-axis 45-degree to 135-degree astigmatisms J45 than patients in the other groups. In 2 myopic LASIK patients, Zernike root-mean-square 4th-order aberrations were higher than in the near-emmetropia group because of higher levels of positive spherical aberration. CONCLUSIONS: Off-axis aberrations can be dramatically affected by conventional myopic and hyperopic LASIK. In myopic LASIK, the increased off-axis refractive errors may have adverse effects on peripheral visual tasks that are dependent on off-axis refractive errors. The relatively low off-axis refractive errors in hyperopic LASIK patients may improve peripheral visual tasks.