Astigmatism in Chinese primary school children: prevalence,change, and effect on myopic shift

Purpose

To study the prevalence, type, and progression of astigmatism in primary school children, and its effect on myopic shift.

Study design

A prospective study carried out in a primary school in southern Taiwan.

Methods

The study was performed on a subset of children, one year after initial examination. Refractive error measured by cycloplegic autorefraction was the main study outcome. Astigmatism was recorded as negative cylinder form, and we defined clinical significant astigmatism (CSA) as cylinder refraction -1.0 D or greater. Myopia was defined as a spherical equivalent refraction (SER) of -0.50 D or greater.

Results

Three hundred sixty-two children, mean age was 8.97 y/o (SD 1.41; range 7 to 11 y/o) participated in the study. One hundred nineteen (32.9 %) subjects had CSA at the initial screening. The mean cylinder refraction was -0.80 + 0.84 diopters (D) (-5.25 D to 0.00 D), with predominant with rule astigmatism (69.7%). In the 183 children studied longitudinally, the mean cylinder refraction was reduced from -0.74 D to -0.58 D (p< 0.05). The cylinder refraction in the initial CSA group was not associated with SER change (p=0.99) or axial length change (p=0.55). Compared to the initial non-CSA group, the initial CSA group had no significant difference in axial length elongation (p=0.20).

Conclusion

The prevalence of astigmatism was not low in the Chinese primary school children and with-the-rule astigmatism was predominant. The astigmatism decreased during the 1 year follow-up. The CSA was not associated with myopia progression (p=0.99).

     

Incidence and progression of astigmatism in Singaporean children

PURPOSE: This study investigated the incidence and progression, as well as factors associated with changes in astigmatism in school children. METHODS: This was a prospective cohort study. Children 7 to 9 years of age, of Chinese, Malay, and Asian Indian ethnicity, were examined annually over a 4-year period. Cycloplegic autorefraction was performed. A questionnaire was used to evaluate risk factors for incidence and progression of astigmatism. RESULTS: The cumulative 3-year incidence rate of astigmatism was 33.6% (cylinder power of 0.5 D or worse) or 11.5% (cylinder power of 1.0 D or worse). Myopic children had a higher incidence rate of astigmatism than nonmyopes (P <0.001). The mean J0 change per year was 0.012 D (95% CI: 0.007-0.018), whereas J45 did not show a significant change each year (mean, 0.001 D per year). Chinese children had greater worsening of J0 per year (P <0.001). Girls also had significantly greater progression of J0 than did boys (P <0.001). Similarly, myopia at baseline (P <0.001) and the hours of computer use (P=0.049) were associated with a greater progression rate of J0. J0 tended to improve in children with compound hyperopic astigmatism, worsen in children with compound myopic astigmatism, and remain stable in mixed astigmatics. CONCLUSIONS: Although there was minimal progression of astigmatism in school age children (0.44-0.53 D) over this period of follow-up, incident cases of astigmatism (>1.0 D) were not uncommon. The progression rate of astigmatism was affected by the ethnicity, presence of myopia, axis, and subtype of astigmatism.     

Prevalence rates and epidemiological risk factors for astigmatism in Singapore school children.

PURPOSE: This study examined the prevalence rate of astigmatism and its epidemiological risk factors in Singapore school children. METHODS: In a study of school children aged 7 to 9 years old in two schools in Singapore in 1999, a detailed questionnaire was administered to parents regarding reading or close-work habits, past history of close-work, family history, and socioeconomic factors. Cycloplegic refraction was performed five times in each eye. Defining astigmatism as worse than or equal to 0.5, 0.75, and 1 D cylinder in the right eye, the prevalence of astigmatism was calculated. RESULTS: The study population consisted of 1028 children. The prevalence rate of astigmatism (worse than or equal to 1 D cylinder) was 19.2% (95% confidence interval, 16.8 to 21.6). This was not different between genders, ethnic groups, or age (p > 0.05). With-the-rule astigmatism was more common than against-the-rule astigmatism. The prevalence of astigmatism and myopia was 9.8% (95% confidence interval, 8.0 to 11.6). A high AC/A ratio was associated (p = 0.003) with astigmatism, even after exclusion of myopic children. On vectorial analysis, J0 and J45 were associated with the number of hours of playing video games, whereas J45 was also associated with computer use. Only J45 was associated to male gender, a high AC/A ratio, and a family history of myopia. CONCLUSIONS: The prevalence rate of astigmatism (> or = 1 D) was 19%. Playing video games and computer use may be associated with astigmatism severity, although the presence of astigmatism (> or = 1 D) was not associated with any nearwork factors. A family history of myopia was associated with oblique astigmatism severity. A high AC/A ratio is associated with astigmatism, and this requires further investigation.     

Correlation between corneal topography and subjective refraction in idiopathic and surgery-induced astigmatism

PURPOSE: To study the correlation between subjective refraction and corneal topography. To compare the topographic analysis of surgically induced astigmatism (cataract and penetrating keratoplasty) with that of idiopathic astigmatism. METHODS: Subjective astigmatism, subjective spherical equivalent, best spectacle-corrected visual acuity (LogMAR units), and videokeratoscopy using the EyeSys 2000((R)) device (axial, tangential, and refractive power) were recorded in 100 eyes with idiopathic astigmatism, 100 eyes after cataract surgery, and 100 eyes after penetrating keratoplasty. Topographies were classified according to pattern (Bogan classification) and asphericity (shape factor: prolate or oblate). RESULTS: The asphericity shape distribution was significantly different between the 3 groups (p<0.001). The shape of idiopathic astigmatism was almost always prolate (90%) whereas the oblate shape was more frequent in the penetrating keratoplasty group (75%). There was no significant difference in topographic pattern distribution between the 3 groups (p=0.11). The asymmetric bow tie pattern was the most common topographic pattern. Topography pattern classification was significantly correlated with the subjective astigmatic cylinder. (r(s)=0.60, p<0.001). Unlike the round and oval patterns, the bow tie pattern was associated with the high subjective cylinder. Correlation between the subjective cylinder, the refractive power cylinder, and the axial power cylinder was strong (r(s)=0.92 p<0.001), but it was weak for the tangential power cylinder (r(s)=0.72 p<0.001). The correlation between the subjective spherical equivalent and central cornea power was poor (r(s)<0.37, p<0.001). Subjective astigmatic cylinder showed the strongest correlation with best spectacle-corrected visual acuity (r(s)=0.70, p<0.001), whereas the predicted corneal acuity, corneal uniformity index, asphericity, and refractive power symmetry index were poorly correlated with it (r(s)<0.54, p<0.001). CONCLUSION: Despite the difference in the asphericity shape, the topographic pattern was similar in the 3 groups. The pattern type was significantly correlated with the subjective astigmatic cylinder. Topographic indices failed to predict visual acuity, while the subjective cylinder showed a strong correlation with visual acuity.     

Pterygium in Indonesia: prevalence,severity and risk factors

AIM: To determine prevalence rates, severity, and risk factors for pterygium in adults in provincial Indonesia and to validate a clinical grading scheme in a population based setting. METHODS: A population based prevalence survey of 1210 adults aged 21 years and above was conducted in five rural villages and one provincial town in Riau province, Sumatra, Indonesia, an area near to the equator. A one stage household cluster sampling procedure was employed: 100 households were randomly selected from each village or town. Pterygia were graded for severity (T1 to T3, by visibility of episcleral vessels) and the basal and apical extent measured by an ophthalmologist (GG) with a hand held slit lamp. Refraction was measured by hand held autorefractor (Retinomax). Face to face household interviews assessed outdoor activity, occupation, and smoking. The participation rate was 96.7%. RESULTS: The mean age was 36.6 years (SD 13.1), 612 were male. The age adjusted prevalence rate of any pterygium was 10.0% (95% confidence intervals (CI) 8.2 to 11.7) and of bilateral pterygia was 4.1% (95% CI 2.9 to 5.3). There was a significant dose-response relation with age (2.9% (95% CI 0.4 to 5.8) for 21-29 years versus 17.3% (95% CI 10.4 to 24.2) 50 years and above; p for trend <0.001) and occupations with more time outdoors (p for trend = 0.02). This was true for both sexes, all grades of lesion (T1 to T3), and bilateral disease. A multivariate logistic regression model showed pterygium was independently related to increasing age and outdoor activity 10 years earlier. The mean basal diameter = 3.3 mm (SD 1.51, range 0.1-9.5) and extent from limbus = 1.4 mm (SD 1.18, range 0.1-8.0). Higher grade pterygia were larger for basal and apical extent (p for trend <0.001). The presence of pterygium was associated with astigmatism (defined as cylinder at least -0.5 dioptres (D); p <0.001). This association increased with increasing grade of lesion (p for trend <0.001). Median cylinder for those with pterygium (-0.50 D) was greater than for those without (-0.25D), (p <0.001), and increased with higher grade of lesion (p for trend <0.001). For eyes with pterygia, magnitude of astigmatism was associated with greatest extent from the limbus, (p = 0.03), but not basal width (p = 0.99). CONCLUSIONS: There is a high prevalence rate of pterygia in provincial Sumatra. The independent increase with age and past outdoor activity (a surrogate for sun exposure) is consistent with previous findings. Clinical grading of pterygium morphology by the opacity of the lesion was a useful additional marker of severity.     

The association of astigmatism and spherical refractive error in a high myopia cohort.

PURPOSE: The purposes of this study were to determine whether the degree of myopia influences the presence and degree of total astigmatism, and to assess risk factors of astigmatism in patients with familial nonsyndromic severe myopia. METHODS: We performed a retrospective study of 217 subjects from families with two or more subjects from successive generations with a myopic spherical refractive error of at least -5 D or greater in one eye. Mean myopic spherical equivalent was -10 D and the mean age of myopia onset was 7 years. Refractive error measurements were obtained and the association between the degree of myopia and cylinder power was examined by correlation analysis. RESULTS: The prevalence of astigmatism (1.0 D of cylinder) was 36.1%. With-the-rule astigmatism was most common (55.8%), and the majority of astigmats had between 1.0 and 2.5 D of cylinder (77.6%). Statistically significant associations were found between the presence of astigmatism and risk factors of age and the age of myopia onset. In those patients with astigmatism, however, there was a moderate correlation between the degree of spherical equivalent and cylinder power (r = -0.34, p < 0.0001). Younger age (<16 years) (p = 0.03) was associated with higher cylinder power. CONCLUSIONS: In severely myopic patients, there is a high prevalence of astigmatism that is predominantly with-the-rule. The degree of myopic spherical refractive error is correlated with astigmatism severity but is not a risk factor for the presence of astigmatism.     

Corneal and lenticular components of total astigmatism in a preschool sample.

PURPOSE: To examine the contribution of corneal and lenticular components to total astigmatism in preschool low and high astigmats to determine whether there was any compensation for high astigmatism by the lenticular component. METHODS: Cycloplegic refractive and keratometric measures using the Retinomax K-Plus (Nikon Inc., Melville, NY) were conducted on 129 children (mean age, 51.1 +/- 8.4 mo) in Oxford County, Canada. We divided the sample into high astigmats (total cylinder > or =1 D; mean, 1.38 +/- 0.43 D; n = 29) and normal astigmats (total cylinder < or =0.75 D; mean, 0.22 +/- 0.20 D; n = 100). Measures of total and corneal cylinder were transposed into J0 and J45 components, where positive and negative J0 values quantified with-the-rule (WTR) and against-the-rule astigmatisms, respectively, and J45 quantified oblique astigmatism. RESULTS: WTR astigmatism was dominant in both the high and normal astigmatic group. J0 and J45 components of corneal astigmatism were highly correlated with total astigmatism in high astigmats, whereas only J0 was significantly correlated with total astigmatism in normal astigmats. Although the magnitude of total and corneal cylinder was significantly greater in high astigmats, overall lenticular cylinder was similar in both groups. However, the Fourier transforms showed high astigmats to have significantly lower lenticular J0 and higher lenticular J45 than the normal astigmats. CONCLUSIONS: Astigmatism in 3- to 5-year-old children is primarily corneal. In preschool children, the lens does not vary in response to high amounts of corneal WTR astigmatism, and in fact, it increases the oblique astigmatism component when the corneal component is high. In high astigmats, lenticular astigmatism contributes to both J0 and J45 components, whereas the corneal contribution is primarily J0.     

3--6岁儿童睫状肌麻痹后散光变化的矢量分析

目的对3~6岁学龄前儿童的散光值进行矢量分析,并研究睫状肌麻痹对散光的影响。方法横断面研究。2012年1—10月选取上海市杨浦区3-6岁儿童14116例．其中男孩7310例,女孩6806例。平均年龄（4．0±0．8）岁。采用CanonRK—F1型全自动电脑验光仪对所有儿童行睫状肌麻痹前后的电脑验光,记录全眼散光及轴向;ZeissIOLMaster测量眼轴长度。每例均取右眼进行统计分析。对完成所有检查的13080例有效样本的全眼散光进行Thibos矢量分析,将近视性散光转换为M、Jn和J45。睫状肌麻痹前后的各数据差异采用配对t检验进行统计分析。结果睫状肌麻痹前后,3～6岁儿童主要表现为顺规性散光,特别是在柱镜值≥1．00D的高度散光组,其次为斜轴性散光．最后为逆规性散光。在睫状肌麻痹后,高度散光的比例略有下降,从19．96％降至18．41％;而O．25～0．75D的正常散光比例略有增加,从28．59％增加到33．72％。同时在睫状肌麻痹后,顺规性散光比例增高,逆规性散光和斜轴性散光比例都略有下降。而在高度顺规性散光组中,睫状肌麻痹后全眼散光值下降[（-1．612±0．763）D vs．（-1．457±0．645）D,t=-6．396,P〈0．01）,其中主要表现为J0成分的降低,J45成分保持不变。结论睫状肌麻痹对散光也有着一定程度的影响,尤其是对高度顺规性散光。     

恩施市某幼儿园926例学龄前儿童散光的流行病学调查

目的:研究学龄前儿童散光类型、程度及轴位的发生情况.方法:随机选取恩施市城区某幼儿园926例3~<7岁学龄前儿童进行视力筛查,以散光度(|DC|)≥0.50D为纳入标准,对检出的308例445眼散光眼进行统计分析.结果:散光(|DC|≥0.50D)检出308例(36.2%),其中双眼散光137例,单眼散光171例;五种散光类型发生率分别为复合远视40.7%,混合35.5%,复合近视8.5%,单纯近视8.3%,单纯远视7.0%;三种散光程度发生率分别是轻度69.0%,中度16.6%,高度14.4%;不同散光轴向发生率分别为顺规54.9%,逆规28.8%,斜轴16.6%;双眼散光眼中双眼轴向对称35.8%,不对称64.2%.结论:学龄前儿童散光类型以复合远视和混合散光为主;散光程度以轻度为主,随年龄增加中度、高度散光发生率有上升趋势.     

Prevalence, incidence, and progression of myopia of school children in Hong Kong

PURPOSE: To determine the prevalence, incidence, and progression of myopia of Chinese children in Hong Kong. METHODS: A cross-sectional survey was initially conducted. A longitudinal follow-up study was then conducted 12 months later. RESULTS: A total of 7560 children of mean age 9.33 (95% confidence interval [CI] = 9.11-9.45; range, 5-16) participated in the study. Mean spherical equivalent refraction (SER) was -0.33 D (SD = 11.56; range, -13.13 to +14.25 D). Myopia (SER 相似文献   

Astigmatism and its Determinants in the Tehran Population: The Tehran Eye Study

Purpose: To determine the prevalence of astigmatism and its epidemiological risk factors in Tehran via a population-based study. Methods: By means of a stratified random cluster sampling, 6497 citizens representing a cross-section of the population of Tehran were selected from 160 clusters. Eligible people were recruited through a door-to-door household survey in the selected clusters and transferred to a clinic for an extensive eye examination and interview. The refractive status was determined with manifest refraction. Astigmatism was defined as cylinder worse than or equal to 0.5 D. High astigmatism was defined as a manifest cylinder ≥1.5 D. Results: Between August and December 2002, 4565 of the 6497 eligible individuals in the sample attended the interview and ophthalmic examination (a participation rate of 70.3%). The age- and gender-standardized prevalence of astigmatism was 50.2% (95% CI, 48.4% to 51.9%) on manifest refraction. High astigmatism was found in 490 right eyes (11.1%; 95% CI, 10.1% to 12.0%). Of 2532 participants with ametropia, 59.6 (95% CI, 57.6–61.5) had astigmatism. The percentages of with-the-rule, against-the-rule and oblique astigmatism were 33.6%, 36.9% and 29.3%, respectively. The proportion of type of astigmatism was significantly related to age (p < 0.001). The univariable analysis of astigmatism between family members yielded odds ratios of 1.47 (95% CI, 1.14 to 1.89, p = 0.003) for the association of astigmatism among siblings. After controlling for age, refractive errors and education, the pairwise sibling association remained statistically significant (OR 1.43, 95% CI, 1.08 to 1.88). Conclusion: These findings revealed a high prevalence of astigmatism in the population. Age, education and ametropia were the main predictors of astigmatism in Tehran. Our findings should be considered for case finding and astigmatism correction programs. Our data confirmed a modest familial aggregation for astigmatism.     

Correlation among refractive, keratometric and topographic astigmatism after myopic photorefractive keratectomy

BACKGROUND: Photorefrative keratectomy can be used to flatten the curvature of the anterior cornea and reduce the myopic refraction of the eye. This leads to unphysiological topographical changes of the cornea and may alter the conditions for examinations of corneal surface topography. The purpose of this study was to check for mutual agreement of three different methods of assessment of astigmatism before and after myopic photorefractive keratectomy (PRK). PATIENTS AND METHODS: Forty-seven eyes of 28 patients (age 32.7+/-6.6 years) following PRK using an 193-nm excimer laser were included in this study. 37 eyes were treated for pure myopia (-4.9+/-2.4 D) and 10 eyes for myopic astigmatism (sphere -2.0 to -7.0 D, cylinder -1.0 to -3.0 D). Preoperatively and at 18 months postoperatively, subjective refractometry, keratometry and topography analysis were performed. The axes of topographic and keratometric cylinder were standardized periodically (180 degrees) with respect to the refractive cylinder axis. RESULTS: Pre- and postoperatively, the absolute astigmatism values correlated highly significantly between all three methods (P< or =0.001). The mean refractive cylinder was 0.65+/-0.61 D preoperatively and 0.46+/-0.41 D postoperatively (P=0.2). The mean keratometric astigmatism was 1.14+/-0.64 D before and 0.94+/-0.50 D after PRK treatment (P=0.2). Among the three methods, the mean topographic astigmatism was the highest (P<0.001) preoperatively (1.31+/-0.56 D) and postoperatively (1.21+/-0.52 D) (P=0.3). In eyes treated for pure myopia, no difference between pre- and postoperative refractive, keratometric and topographic astigmatism was detected (P>0.5). The axes of both topographic and keratometric astigmatism correlated highly significantly with the refractive cylinder axis (R> or =30.9, P<0.0001). CONCLUSION: Up to 2 years after myopic PRK, the difference between refractive and keratometric astigmatism does not differ from the preoperative value, indicating an even corneal surface. The absolute astigmatism values and the cylinder axis correlated well between subjective and objective methods of astigmatism assessment. Thus, objective measurements may be helpful in determining the cylinder component of best spectacle correction after PRK. However, topographic analysis overestimates astigmatism values systematically before and after PRK.     

Comparison of EyeSys videokeratoscope algorithms in the evaluation of idiopathic and postoperative astigmatism

PURPOSE: To compare the accuracy and reproducibility of the Eye Sys videokeratoscope algorithms for analyzing idiopathic and surgery-induced astigmatism analysis. METHODS: Refractive astigmatism, videokeratoscopy (axial, tangential and refractive power), autorefractometry, autokeratometry, and keratometry were recorded in 20 patients with idiopathic astigmatism, 40 patients who had undergone cataract surgery and 40 patients who had undergone penetrating keratoplasty. For each eye, 2 successive videokeratoscopy were recorded. RESULTS: Both cylinder and axis provided by the tangential algorithm are significantly less reproducible than the cylinder and axis provided by the axial and refractive algorithms (P < 0.001). Cylinders provided by the axial and refractive algorithms showed a stronger correlation with subjective cylinder (rs > 0.89; p < 0.001) than the cylinder provided by the tangential algorithm (rs = 0.66; p < 0.001). Both keratometric axis and autokeratometric axis showed the strongest correlation with subjective axis (rs > 0.92; p < 0.001). The accuracy and reproducibility were higher for the topographic "bow tie" patterns than for the other topographic patterns. CONCLUSION: The axial and refractive algorithms of the Eye Sys videokeratoscope are more accurate and reproducible than the tangential algorithm for analyzing idiopathic or surgery-induced astigmatism.     

Refractive errors in neurofibromatosis type 1 and type 2

OBJECTIVE: To document the prevalence of refractive errors in patients with neurofibromatosis type 1 (NF1) and type 2 (NF2) and to compare it with that of age- and sex-matched controls. METHODS: 82 patients with NF1, 21 patients with NF2 and 103 age- and sex-matched controls were evaluated in this prospective observational case-control study. Cycloplegic autorefraction and dilated fundus examination were performed. Myopia was defined as the spherical equivalent refraction of at least -0.50 diopters (D), hyperopia as the spherical equivalent refraction of at least 2.0 D and astigmatism as the cylinder of at least 1.0 D. Main outcome measures were refractive error, IQ, years of education, height, weight and body mass index (BMI). RESULTS: The prevalence of myopia was 23.1% in patients with NF1, 23.8% in patients with NF2 and 16.5% in age- and sex-matched controls. These differences were significant (p<0.03, p<0.03), and adjusting for intelligence, education, height, weight and BMI increased the significance of this finding (p<0.001, p<0.001). The prevalences of astigmatism and hyperopia were similar in both groups. CONCLUSION: A high prevalence of myopia seems to be an additional feature of NF1 and NF2.     

High prevalence of astigmatism in the 40- to 64-year-old population of Shahroud, Iran

Background: The prevalence of astigmatism, its axis and determinants were determined in the 40‐ to 64‐year‐old population of Shahroud, Iran. Design: Population‐based cross sectional study. Participants: Using random cluster sampling, 6311 subjects were invited for eye examinations. Of 5190 participants (response rate = 82.2%), data of 5020 were eligible for analysis. Methods: Participants received visual acuity measurement, manifest refraction and eye examinations. Main Outcome Measures: The prevalence of astigmatism based on cylinder powers of more than 0.5, 1 and 3 D were studied. Results: The prevalence (and 95% confidence interval) of astigmatism based on a cylinder power worse than 0.5, 1, and 3 D was 49.1% (47.6–50.5), 24.1% (22.9–25.3), and 3.4% (2.9–3.9), respectively. In a multiple logistic regression model, the prevalence of astigmatism was higher in men (odds ratio = 1.25) and increased with age (odds ratio for each 5 years = 1.21). Higher education was found to be inversely correlated to astigmatism (P < 0.001). The prevalence of with‐the‐rule, against‐the‐rule and oblique astigmatism was 12.6%, 25.9% and 10.6%, respectively. Oblique astigmatism was significantly higher in women and the older age groups (P < 0.001). Against‐the‐rule astigmatism increased with age from 19.9% in the age group of 40–44 to 37.0% in the age group of 60–64 (P < 0.001). Conclusions: In comparison with those studies conducted in Iran and other countries, the prevalence of astigmatism was higher in this study. Astigmatism was higher in men and age had an important role in astigmatism and its axis. The prevalence of against‐the‐rule and oblique astigmatism increased with age.     

Cycloplegic refraction in preschool children: comparisons between the hand-held autorefractor, table-mounted autorefractor and retinoscopy

Aims: It is common for refraction to be measured using different testing methods in children, with much debate still ongoing on the preferred method. Therefore, we compared cycloplegic refraction measurements using three objective methods in a large cohort of children. Methods: We present the findings from a total of 51 children who were recruited and examined as part of the Strabismus, Amblyopia and Refractive error in Singapore preschool children (STARS) study. Each child underwent a comprehensive eye examination, which included cycloplegic refraction using a hand‐held autorefractor (Retinomax), a table mounted autorefractor (Canon FK‐1) and streak retinoscopy. Spherical equivalent (SE) was calculated as (sphere + half of minus cylinder) and astigmatism was determined using the negative cylindrical component. Results: The current study sample consisted of 29 boys and 22 girls aged between 24 and 72 months (mean age 52.3 months). The mean spherical equivalent (SE) using the table‐mounted autorefractor (1.03 ± 1.64 D) was not significantly different from the streak retinoscopy (1.09 ± 1.58 D, p = 0.66). However, the mean SE using the hand‐held Retinomax (0.80 ± 1.43 D) was significantly different (more ‘minus’p = 0.0004) to streak retinoscopy. The astigmatism measured using the hand held (?0.89 ± 0.51 D) and table‐mounted autorefractor (?0.83 ± 0.61 D) were significantly greater than that obtained with streak retinoscopy (?0.58 ± 0.56, p = 0.0003). Conclusions: The table‐mounted autorefractor provided a reading more similar to that of streak retinoscopy than to that of the hand‐held autorefractor. However, there were only small differences in mean SE (<0.32 D) between the hand‐held Retinomax and the other methods, which will have implications in research investigations of refractive error.     

Change in refraction and topography after penetrating keratoplasty suture removal

PURPOSE: To study the refractive and topographic modifications induced by penetrating keratoplasty suture removal. METHODS: We prospectively studied 80 corneas from 80 patients who had undergone penetrating keratoplasty. All of the eyes were examined before and after all sutures were removed, respectively at 10.9 5.1 months and 21.5 9.6 months after keratoplasty. Subjective refraction, best spectacle-corrected visual acuity (LogMAR units), keratometry, and corneal topography using the EyeSys 2000((R)) device (axial tangential and refractive power) were recorded. Topographies were classified according to the pattern (Bogan classification) and the asphericity shape (prolate and oblate). RESULTS: Best spectacle-corrected visual acuity (Log MAR units) increased significantly after suture removal (1.1 1.9 lines, plt; 0.001). Suture removal decreased the subjective cylinder (5.01 D 2.06 with suture, 4.11 2.08 without suture; p=0.009). The change in subjective cylinder correlated with the change in topographic pattern(s)=0.67 p<0.001). Conversely to the "bow tie" patterns, the other topographic patterns were more frequent after suture removal. The change in visual acuity was essentially explained by the change in subjective cylinder(s)=0.40 p=0.002). The average central corneal power decreased significantly after suture removal by 0.83 to 1.81 D (p<0.001), whereas the subjective spherical equivalent increased (hyperopization) (-4.07D 3.73 with suture, -3.48 3.40 without suture; p=0.02). The change in central corneal power significantly correlated with the change in subjective spherical equivalent (r(s)()>0.30 plt; 0.001). The corneal power of the mid-periphery did not significantly change after suture removal. Suture removal significantly modified the asphericity shape distribution. (majority of prolate shape with suture, majority of oblate shape without suture, p<0.001). CONCLUSION: Keratoplasty sutures induce a central bulge in the corneal graft. Suture removal induces a decrease in the subjective cylinder and it increases the subjective spherical equivalent (hyperopization) through a decrease in the central corneal power. Suture removal modifies the corneal topographic pattern and shape. Visual acuity improvement after suture removal is mainly explained by the decrease in subjective astigmatism.     

Comparison of Wavelight Allegretto Eye-Q and Schwind Amaris 750S excimer laser in treatment of high astigmatism

Purpose

To compare functional outcomes of Wavelight Allegretto Eye-Q 400Hz and Schwind Amaris 750S excimer laser for astigmatism between 2 and 7 diopters(D).

Methods

Prospective comparative non-randomized case series of 480 eyes assigned in two laser groups and further divided into myopic and mixed astigmatism subgroups. All treatments were centered on corneal vertex. One-year results were compared between the groups. Statistical analysis was performed using z-test.

Results

Both Allegretto and Amaris postoperative uncorrected distance visual acuity (UDVA) improved in comparison to preoperative corrected distance visual acuity (CDVA). The difference was significant in the Allegretto group for myopic astigmatism (p?=?0.017). There was no difference in postoperative UDVA between lasers. Average sphere decreased in all groups for both lasers (p?p?p?p?p?p?= 0.023, mixed astigmatism p?Conclusion Both lasers are effective in terms of UDVA, CDVA, spherical correction, and preservation of high-order aberrations. However, Amaris was more effective in cylinder correction.     

Change in vision disorders among Hong Kong preschoolers in 10 years

Background: To determine the change in refractive error and the prevalence of amblyopia and strabismus among preschool children in Hong Kong over a period of 10 years. Design: Two cross‐sectional population‐based studies conducted in 1996 to 1997 (part A) and 2006 to 2007 (part B) Participants: Children attending randomly selected kindergarten participated in the study. Methods: Ocular alignment, visual acuity, cover and uncover tests, cycloplegic refraction, slit‐lamp and fundi examination were performed under a standardized testing environment. Main Outcome Measures: The prevalence of amblyopia (best‐corrected visual acuity ≤6/12 in one or both eyes, or a bilateral difference of ≥2 best‐corrected visual acuity lines), strabismus and significant refractive error (hyperopia ≥+2.50 D; myopia ≥?1.00 D; astigmatism ≥2.00 D) among preschool children. Results: Of the 601 children in part A of the study, reduced visual acuity was presented in 3.8%; whereas strabismus was found in 1.8%. The commonest type of refractive error was astigmatism in 6.3% of children, followed by hyperopia (5.8%) and myopia (2.3%). Among 823 children in part B, reduced visual acuity was presented in 2.7% of children, and strabismus was found in 1.7%. The commonest type of refractive error was myopia (6.3%), followed by astigmatism (5.7%) and hyperopia (5.1%). The percentage of children having myopia has significantly increased (P = 0.001). Conclusion: A significant increase in myopia has been noted in Hong Kong preschoolers. Visual screening programmes may need to be tailored to correspond to the local population and be adjusted accordingly from time to time.     

温州地区儿童青少年散光分布特征及其影响因素

目的：分析温州地区5～14 岁儿童青少年的散光分布特征,评估儿童青少年散光发生的主要影响因素。方法：横断面研究。收集2011 年9 月至2016 年3 月在温州医科大学附属第二医院儿童体检中心进行健康体检并同意参加本研究的儿童青少年525 名。对研究对象进行睫状肌麻痹下（1%盐酸环喷托酯滴眼液）下电脑验光, 测量身高、体质量、三围。并对陪同前来的父母进行非睫状肌麻痹电脑验光。收集儿童青少年年龄、性别、父母资料等信息,采用秩和检验、卡方检验及Logistic回归分析儿童青少年散光状态及其相关影响因素。结果：在525 名研究对象中有438 名（83.4%）完成研究,其中存在散光者（≥0.5 D）260名,检出率59.4%。散光在0.50～1.00 D者占80.8%、1.25～2.00 D占11.2%,＞2.00 D占8.1%。散光儿童青少年中肥胖比例更高（χ2=6.347,P =0.042）。散光类型以顺规散光为主（73.8%）,不同性别及各年龄组散光轴向分布差异均无统计学意义（χ2=3.104,P =0.212;χ2=10.578,P =0.102）。经矫正年龄、性别、体质指数后发现,与双方父母均无散光的儿童青少年相比,父母双方中一方有散光的儿童青少年的散光检出率更高（χ2=7.484,P =0.024）。母亲柱镜度增加,儿童青少年患散光的风险明显增加（OR =2.2,95%CI=1.1～4.4,P =0.023）。结论：温州地区参与常规体检儿童青少年的散光检出率为59.4%,以顺规散光为主,母亲有散光可能增加儿童青少年发生散光的风险。