Prevalence of refractive error,presbyopia, and unmet need of spectacle coverage in a northern district of Bangladesh: Rapid Assessment of Refractive Error study

Purpose: To determine the prevalence of refractive error (RE), presbyopia, spectacle coverage, and barriers to uptake optical services in Bangladesh.

Method: Rapid assessment of refractive error (RARE) study following the RARE protocol was conducted in a northern district (i.e., Sirajganj) of Bangladesh (January 2010–December 2012). People aged 15–49 years were selected, and eligible participants had habitual distance and near visual acuity (VA) measured and ocular examinations were performed in those with VA<6/18. Those with phakic eyes with VA <6/18, but improving to ≥6/18 with pinhole or optical correction, were considered as RE and people aged ≥35 years with binocular unaided near vision of <N8 were considered presbyopic.

Result : A total of 3,043 people were examined, of which 143 had RE (4.7%, 95% CI: 3.9–5.5). Among people aged ≥35 years (n = 1402), 869 had presbyopia (62.0, 95% CI: 59.4–64.5). Spectacle coverage for RE and presbyopia were 13.3% (95% CI 7.7–18.9) and 3.2% (95% CI 2.2–4.6), respectively. “Unaware of the problem” was the main reason for not utilizing any optical services among the people with RE (92.8%) and presbyopia (89.5%). Extrapolating the survey findings to the 2011 national census data, the magnitude of RE among people aged 15–49 years in Bangladesh is estimated to be 3,493,980 people (95% CI 2,899,260–4,088,700), of whom 3,029,280 people do not use any spectacles.

Conclusion : The burden of RE and presbyopia is substantial in Bangladesh. Improving awareness and availability of refraction services is required to correct REs and presbyopia in Bangladesh.     

Prevalence and predictors of refractive error in a genetically isolated population: the Norfolk Island Eye Study

Background: We aimed to determine the prevalence and associations of refractive error on Norfolk Island. Design: Population‐based study on Norfolk Island, South Pacific. Participants: All permanent residents on Norfolk Island aged ≥15 years were invited to participate. Methods: Patients underwent non‐cycloplegic autorefraction, slit‐lamp biomicroscope examination and biometry assessment. Only phakic eyes were analysed. Main Outcome Measures: Prevalence and multivariate associations of refractive error and myopia. Results: There were 677 people (645 right phakic eyes, 648 left phakic eyes) aged ≥ 15 years were included in this study. Mean age of participants was 51.1 (standard deviation 15.7; range 15–81). Three hundred and seventy‐six people (55.5%) were female. Adjusted to the 2006 Norfolk Island population, prevalence estimates of refractive error were as follows: myopia (mean spherical equivalent ≥?1.0 D) 10.1%, hypermetropia (mean spherical equivalent ≥ 1.0 D) 36.6%, and astigmatism 17.7%. Significant independent predictors of myopia in the multivariate model were lower age (P < 0.001), longer axial length (P < 0.001), shallower anterior chamber depth (P = 0.031) and increased corneal curvature (P < 0.001). Significant independent predictors of refractive error were increasing age (P < 0.001), male gender (P = 0.009), Pitcairn ancestry (P = 0.041), cataract (P < 0.001), longer axial length (P < 0.001) and decreased corneal curvature (P < 0.001). Conclusions: The prevalence of myopia on Norfolk Island is lower than on mainland Australia, and the Norfolk Island population demonstrates ethnic differences in the prevalence estimates. Given the significant associations between refractive error and several ocular biometry characteristics, Norfolk Island may be a useful population in which to find the genetic basis of refractive error.     

Prevalence and Correlates of Diabetic Retinopathy in a Population-based Survey of Older People in Nakuru,Kenya

Purpose: To estimate the prevalence of and factors associated with diabetic retinopathy (DR) among people aged ≥50 years in Nakuru, Kenya.

Methods: Probability-proportional-to-size sampling was used to select 100 clusters of 50 people aged ≥50 years during 2007–2008. Households within clusters were selected through compact segment sampling. Participants underwent dilated slit lamp biomicroscopy (SLB) by an ophthalmologist and digital retinal photography. Images were graded for DR at the Moorfields Eye Hospital Reading Centre, UK. Diagnosis of DR was based on retinal images where available, otherwise on SLB. Anthropometric measures, including random glucose, and lifestyle factors were measured.

Results: We examined 4414 adults (response rate 88.1%), of whom 287 had diabetes. A total of 277 of these were screened for DR by SLB, and 195 also underwent retinal photography. The prevalence of any DR diagnosed by retinal images among diabetics was 35.9% (95% confidence interval, CI, 29.7–42.6%). The most common grade of DR was mild/moderate non-proliferative DR (NPDR; 22.1%, 95% CI 16.1–29.4%), while severe NPDR and proliferative DR were less frequent (13.9%, 95% CI 10.0–18.8%). SLB significantly underdiagnosed DR compared to retinal photography, particularly for milder grades. Of 87 individuals with DR, 23 had visual impairment (visual acuity <6/12). DR was associated with younger age, male sex, duration and control of diabetes, and treatment compliance. Coverage of photocoagulation in those needing immediate laser was low (25%).

Conclusion: DR remains a threat to sight in people with diabetes in this elderly Kenyan population. Screening diabetics may enable those requiring treatment to be identified in time to preserve their sight.     

Necessity of cycloplegia for assessing refractive error in 12-year-old children: a population-based study

PURPOSE: To compare pre- and postcycloplegic autorefraction in two separate age samples of Australian school children. DESIGN: Population-based cross-sectional study of random cluster samples. METHODS: Autorefraction was performed before and after cycloplegia, using 1% cyclopentolate, in the right eyes of 2,233 12-year-old and 210 6-year-old children. RESULTS: The mean spherical equivalent (SEQ) difference between these measures was 0.84 diopters (D) (95% confidence interval (CI) 0.81 to 0.87 D), more hyperopic in post- than precycloplegic autorefractive assessments in the 12-year-old children and 1.18 D (95% CI 1.05 to 1.30 D) more hyperopic in the 6-year-old children. Precycloplegic autorefraction substantially overestimated the proportion of children with myopia, misclassifying 17.8% aged 12 years and 9.5% aged 6 years. Conversely, precycloplegic autorefraction did not detect moderate to high hyperopia in 2.28% of 12-year-olds and 17.14% of 6-year-olds. CONCLUSIONS: Our findings reinforce the importance of using cycloplegic autorefraction in children up to age 12 years.     

Survey of spectacle wear and refractive error prevalence in USAF pilots and navigators

A retrospective survey of 5000 active aircrew records was performed at 12 United States Air Force (USAF) bases to obtain information about the prevalence of spectacle wear and refractive error. The data revealed that 27.4% of pilots and 51.5% of navigators/weapons systems operators (Nav/WSO) required spectacles when flying. Of the spectacle-wearing pilots, 12.4% required bifocals. Myopia was the predominant refractive error and a relatively large percentage of aircrew members had astigmatism of 0.75 D or more, e.g., 33.1% of pilots. At the time of entry into the USAF, refractive error data were clustered around emmetropia with a definite skew toward hyperopia.     

Age,gender and refractive error association with intraocular pressure in healthy Saudi participants: A cross-sectional study

Purpose

To determine the distribution of intraocular pressure (IOP) and its association with age, gender and refractive error in non-glaucomatous Saudi participants.

Design

Hospital-based cross-sectional observational study during Vision Day Screening Program. Participants: 458 participants living in the Al-Khobar, Saudi Arabia.

Methods

Recruited participants (aged 20 years or over) underwent a comprehensive questionnaire and ocular examination, including measurement of IOP with Perkins hand-held applanation tonometry and autorefraction.

Main outcome measures

The distribution of IOP of either of the eyes (right or left eye by randomization) and associations with age, gender and refractive error.

Results

Median IOP was 15.0 (range: 6–28) mmHg in the total population. There is no significant difference between the overall IOP of male participants, median 15 (range: 6–28) mmHg and female participants, median 16 (range: 6–28) mmHg (p = 0.180). No statistically significant difference in IOP in relation to age comparing 20–45 years group to 46–69 years group was documented (p = 0.751). There was no statistically significant relationship between refractive error category and IOP (p = 0.405). Ocular hypertension with IOP > 21 mmHg was found in 8.7% of the participants.

Conclusion

Variation in IOP by gender, age group and type of refractive error was not statistically significant. The observations need confirmation by study with larger sample representing Saudi population.     

云南省高海拔农村多民族聚居区屈光不正患病率调查

目的:调查中国西南部高海拔农村多民族聚居区人群屈光不正患病率,获得该地区整体人群屈光不正的流行病学资料。方法:采用整群随机抽样的方法选取云南省贡山县常住居民做为调查对象。所有调查对象均接受全面的眼科检查及屈光状态检查。分析屈光不正整体情况及屈光不正发生与年龄、性别、文化程度等相关因素的关系。结果:入选对象3070例中实际接受调查人数为2422例(受检率78.9%)。对4843眼的屈光不正数据进行统计分析:正视眼2635眼(54.4%);近视1106眼(22.8%);远视1102眼(22.8%),其中散光4451眼(91.9%)。正视所占比率随年龄增长呈下降趋势(P<0.05),近视患病率不随年龄增长而增长(P>0.05),远视眼患病率随年龄增长呈上升趋势(P<0.05)。散光的发生中,顺规散光81·6%,随年龄增长顺规呈下降趋势,逆规散光15.1%,随年龄增长呈上升趋势(P<0.05)。女性远视眼患病率较男性人群高(P<0.05)。初中学历以上人群中重度近视发生率较初中以下学历人群为高(P<0.05)。结论:获得中国西南部高海拔偏远山区整体人群屈光不正统计数据,表明受教育程度越高近视发生率越高,年龄改变与散光轴向改变相关。     

Assessment of stereopsis in pediatric and adolescent spectacle-corrected refractive error – A cross-sectional study

Purpose:To assess the level of stereopsis in school children with spectacle-corrected refractive errors using Titmus fly and Randot stereo tests, evaluate the factors associated with the level of stereopsis, and determine the level of agreement between the two tests.Methods:A cross-sectional study was done on 5- to 18-year-old school-children wearing spectacles for at least 1-month duration. Visual acuity was assessed using Snellen’s visual acuity chart, and their spectacle correction being used currently was measured using an auto lensmeter. The level of stereopsis was assessed using Randot and Titmus fly stereo tests. Data were entered using Microsoft Excel and analyzed using IBM-SPSS version 20, Chicago, IL. The associations between stereopsis and type of refractive error, visual acuity, age, and gender were analyzed. An agreement between Randot and Titmus fly test was done using Kappa statistics.Results:A total of 222 children (101 boys and 121 girls; mean age 13 years) were assessed. Astigmatism was the most prevalent refractive error (60.4%), followed by myopia (24.8%) and hypermetropia (1.4%). Thirty children (13.5%) had anisometropia. All hyperopes had normal stereopsis. Children with spherical myopia had better stereopsis, followed by astigmatism and anisometropia in the same order (P = 0.036). Children with anisometropia ≤1.5 D had better stereopsis than anisometropia more than 1.5 D. Stereopsis was also found to have no correlation with the age and visual acuity at the time of testing or the age at which the child first started wearing spectacles. Stereopsis values obtained from Randot and Titmus fly stereo tests showed moderate agreement with Kappa value 0.581.Conclusion:Anisometropia and astigmatism are the most critical factors determining the level of stereopsis in refractive errors.     

A population-based survey of the prevalence of refractive error in Malawi

Refractive errors, particularly myopia, are a common problem in industrialized countries, but the impression exists that myopia may be relatively uncommon in non-industrialized societies.

We conducted a population-based survey of refractive error in two groups of Malawians: a group of rural agricultural workers (n = 510) and a group of students at an urban teachers' college (n = 534).

The overall prevalence of myopia was low; 2.5% (95% confidence interval 1.3%, 3.7%) of participants had an error of-0.5 D or greater. The mean refractive error (right eye) in the urban student group was +0.52 D compared to +0.62 D among the rural agricultural workers and the excess myopia was accounted for by significant myopia (≥-0.75 D) in a few individuals, rather than an overall shift towards myopia within the urban student group. Among the rural agricultural workers, literacy predicted refractive error (right eye), with a mean of +0.59 D in the rural literate compared to +0.67 D in the rural illiterate.

These findings support the notion that myopia is uncommon in non-industrialized societies and that it is associated with increased literacy but we have not identified specific risk factors within this group to predict the occurrence of significant myopia. In settings such as Malawi, refractive services should be targeted to urban centers, where more educated populations are likely to be found.     

Aphakia: perceptual and refractive problems of spectacle correction

The perceptual variations due to removal of the crystalline lens and the employment of powerful plus spectacle lenses are described. These include refractive change, distortion, magnification, limitation of the visual field, peripheral vision, sensitivity of light and changes in the required convergence. The technique for satisfactory refraction of the aphakic eye is discussed and the elements leading to error such as vertex distance and pantoscopic tilt are considered. Other factors necessary for understanding the refraction such as the apparent accommodative range and the limitations affecting field charting are also covered. Method of securing binocularity via contact lens-spectacle combinations for monocular cases, and the need for rehabilitative procedures conclude this treatment.     

Residual refractive errors in pseudophakic eyes and related factors: a population-based study

AIM: To determine residual refractive error after cataract surgery in pseudophakic eyes and its relationship with age, sex, and axial length (AL). METHODS: In this population-based cross-sectional study, the sampling was performed on individuals aged 60y and above in Tehran, Iran using a multi-stage stratified random cluster sampling method. Pseudophakic eyes with a best-corrected visual acuity of 20/32 or better were analyzed and their refractive results were reported. RESULTS: The mean spherical equivalent (SE) refraction was -0.34±0.97 diopters (D) and the mean absolute SE was 0.72±0.74 D with a median of 0.5 D. Moreover, 32.68% (n=546, 95%CI: 30.27%-35.08%), 53.67% (n=900, 95%CI: 51.23%-56.1%), 68.99% (n=1157, 95%CI: 66.96%-71.02%), and 79.73% (n=1337, 95%CI: 77.69%-81.76%) of the eyes had a residual SE within ±0.25, ±0.50, ±0.75, and ±1.00 D of emmetropia, respectively. According to the multiple logistic regression model, increasing age was associated with a statistically significant decrease in predictability for all cut points. Moreover, the predictability based on all cut points was significantly lower in individuals with an AL longer than 24.5 mm than in those with an AL between 22 to 24.5 mm. CONCLUSION: Based on the results, the accuracy of intraocular lens (IOL) power calculation is lower for those who underwent cataract surgery during the last 5y in Tehran, Iran. Among the most important influential factors, the choice of IOL or it’s power disproportionate to eye conditions and age can be mentioned.