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PubMed1983

Predicting age of onset for individuals at risk for phakic retinal detachment.

Three hundred sixty-five cases of nontraumatic phakic retinal detachment were examined by analysis of covariance to determine the degree of association among type of detachment, refractive error, and age of onset. The combination of type of detachment and refractive error explained 57% of the variation in age of onset. Discrimination among types of detachment by variation in mean age was limited. Discrimination among types of detachment by variation in mean refractive error could not be established. Detachments due to vitreoretinal adhesion, lattice degeneration, and retinal dialysis differed significantly in mean age of onset and regression of age on refractive error. A regression model was created to predict from refractive error the age of onset with 95% confidence limits for individuals who appear to be at risk for these types of detachment.

Adolescent↗
PubMed1988

Quantitative photorefraction using an off-center flash source.

When an eye is refracted by "eccentric photorefraction" with a flash source off-centered from a camera lens, a crescent of light is formed in the margin of the pupil. The size of the crescent varies directly with the eye's refractive error. This photographic method has been used in vision screening studies of young children where the appearance of a crescent indicated that the refractive error was above a certain threshold. Usually quantification of the refraction could not be achieved by the photorefractor but relied upon subsequent testing using retinoscopy. My research aimed to expand eccentric photorefraction so as to enable it to provide quantification of the eye's refractive error. This was achieved by varying the eccentricity of the flash source from the camera lens and then calibrating the instrument over a large range of refractive errors. The calibration modified a previously derived optical relation which defined the eye's refractive error in terms of the eccentricity of the source for a given pupil size. Eccentric photorefraction of 26 infants and children aged 7 to 48 months showed a good correlation with retinoscopy (r = 0.82). It is concluded that this method would be complementary to other photorefractive methods (e.g., isotropic) particularly as it is able to measure a large range of refractive errors once the astigmatic meridians of the eye are known.

Calibration↗
PubMed1996

[Ocular refraction in Zaire].

PURPOSE: to determine frequencies of refractive errors in Zairian blacks and to investigate the influence of race upon refraction. METHODS: we examined the records of all patients seen at the department of Ophthalmology from 1963 to 1972. Refraction was measured by objective (skiascopy) or subjective methods. RESULTS: we found 4326 patients with ametropia, about 16% of the total. The records of 2594 Zairian patients with refractive errors were compared to those of 1417 non Zairian black patients and 315 Caucasian patients. The frequency of spherical refractive errors in Zairian black patients was 56%: (simple myopia: 33% myopia over 5 D: 1%, hypermetropia: 22%), astigmatism was seen in 44% (myopic astigmatism: 31% and hypermetropic astigmatism: 11%). The data of Zairian were similar to those of non-Zairian black patients. Spherical refractive errors in Caucasian patients were found in 46% of the patients (simple myopia: 19%, myopia over 5 D: 2%, hypermetropia: 25%). Astigmatismatic errors were seen in 54% (myopic astigmatism: 27%, hypermetropic astigmatism: 24%, mixed astigmatism: 3%). Hypermetropia increased with age in all groups, but slightly earlier in Zairian patients. CONCLUSION: Although the data of refractive errors did not show significant differences between Zairian and Caucasian patients, hypermetropic astigmatism seems to be less frequent and myopia more frequent among Zairian patients.

Adolescent↗
PubMed2001

Development of the refractive state in eyes of ostrich chicks (Struthio camelus).

OBJECTIVE: To follow the development of the refractive error in the eyes of ostrich chicks from age 0 to day 37 after hatching. ANIMALS: 35 ostrich chicks. PROCEDURES: Spot retinoscopy was conducted to assess refractive error in ostrich chicks. Seventy eyes of 35 ostrich chicks were examined. Of these, 18 chicks were followed over time. At least 4 serial measurements (at 2- to 7- day intervals) were conducted in each of these chicks from day 1 to 37 after hatching. Seventeen additional chicks were examined on days 0, 3, 12, and 19 after hatching. RESULTS: Ostrich chicks were myopic at hatching, with a mean +/- SD refractive error of -4.47 +/- 0.15 diopters (D). The refractive error rapidly decreased during the first week of life, and by day 7 after hatching, chicks were slightly hyperopic, with a mean refractive error of 0.42 +/- 0.12 D. After day 7, there were no significant differences in the mean refractive error. CONCLUSIONS: The development of optics in the ostrich eye appears to be unique among animals and is characterized by myopia at hatching, rapid onset of emmetropia, and minimal variation in refractive error among chicks.

Animals↗
PubMed1985

Intraocular lens calculation in combined penetrating keratoplasty, cataract extraction and intraocular lens implantation.

We retrospectively studied 53 consecutive triple procedures (combined penetrating keratoplasty, cataract extraction and intraocular lens implantation) performed at the Bascom Palmer Eye Institute from January 1980 through August 1983. Most patients had at rest six months of follow-up. The final postoperative refractive error was compared to the predicted refractive error using the preoperative axial length and the estimated keratometry readings. The deviation from the predicted refractive error was correlated with the source of preoperative keratometry readings, the degree of donor oversize, and the donor age. We found that using keratometry readings from the operated eye resulted in more accurate intraocular lens calculations than using estimated keratometry readings not obtained from either eye (P less than .05).

Adolescent↗
PubMed1995

Clinical evaluation of refractive techniques.

BACKGROUND: The accuracy of two commercially available auto kerato-refractometers (Shin-Nippon Automatic Ref-Keratometer model RC380 and Topcon Auto Kerato-Refractometer model KR-3100) and one autokeratometer (Alcon Systems Auto-Keratometer) was compared to that of subjective refraction and conventional keratometry. METHODS: Refractive error and corneal curvature were measured on 20 subjects. Measurements were converted from the standard clinical format of sphere, cylinder and axis to a vector format to assess the contribution of spherical and cylindrical errors simultaneously. RESULTS: For measurements of refractive error taken in immediate succession, the Shin-Nippon instrument was found to be more repeatable than the Topcon instrument. This trend reversed when subjects were realigned between measurements. The 95 percent confidence limit for precision for subjective refraction was considerably greater: 93 percent of subjective refractions resulted in visual acuities better than or equal to 6/6, compared with 85 percent for the Topcon instrument and 45 percent for the Shin-Nippon instrument. Each of the methods for measuring corneal curvature showed minimal bias and comparable precision. CONCLUSIONS: Although subjective methods of determining refractive error generally achieved the same or better visual acuity as the automated methods, they displayed considerably poorer precision. Each of the methods of measurement of corneal curvature produced similar results.

Adult↗
PubMed2006

Prevalence of visual impairment and blindness in a Nairobi urban population.

OBJECTIVE: To determine the prevalence and causes of visual impairment and blindness among Kibera slum dwellers. DESIGN: Population based Survey. SETTING: Kibera Slums, Kibera Division, Nairobi, Kenya. SUBJECTS: One thousand four hundred and thirty eight randomly selected slum dwellers. RESULTS: The prevalence of blindness and visual impairment was 0.6% (95% CI: 0.21 to 1.0), and 6.2% (95% CI: 4.95 to 7.15) respectively. 37.5% of those found blind were due to cataract followed by refractive errors 25.0%. 58.1% of those with visual impairment had refractive errors while 35.5% had cataracts. Females had a higher prevalence of visual impairment compared to males but the difference was not statistically significant (P = 0.104). CONCLUSIONS: Prevalence of blindness in Kibera slums is slightly lower than the estimated national average (0.7%) while that of visual impairment is almost three times higher. The leading causes of blindness are cataract followed by refractive errors. For visual impairment, refractive error was the leading cause followed by cataract. RECOMMENDATION: Kibera slum dwellers are in need of comprehensive eye care services offering cataract surgery and low cost spectacles.

Adolescent↗
PubMed1997

Reproducibility and accuracy of measurements with a hand held autorefractor in children.

AIM: To determine reproducibility and accuracy of the Nikon Retinomax autorefractor when used with children who were made cycloplegic. METHODS: Autorefraction and retinoscopy or subjectively refined retinoscopy (where, under the patient's direction, the refraction was varied until the best visual acuity was achieved) were performed on the right eye of 47 children, age 11-93 months. Autorefraction was performed using the Nikon Retinomax, which provides up to eight measured values of refractive error and one representative measurement of refractive error. RESULTS: Autorefractor measurements were successfully obtained from 7/9 children age 3 years or younger, and from all older children. Vector methods were used to calculate differences. Retinomax reproducibility averaged 0.43 D. Unbiased Retinomax and retinoscopy measurements differed by an average of 0.82 D. Unbiased Retinomax and subjectively refined retinoscopy differed by an average of 1.03 D. CONCLUSIONS: Reproducibility of Retinomax measured values in children is comparable with reproducibility of retinoscopy, subjective refraction, and autorefraction measurements in adults. Agreement between Retinomax and retinoscopy and agreement between Retinomax and subjective refinement in children is comparable with agreement between autorefraction and subjective refraction in adults. The study indicates that the Retinomax is a useful instrument for measuring refractive errors in young children.

Child↗
PubMed2005

[New incision versus corneal flap uncover: comparison of two techniques of repeated surgery after primary LASIK in myopia].

An advantage of the LASIK method is the possibility of repeated surgery in case of residual refractive error after the primary surgery. In the second surgery two techniques are used: the technique of the new incision (secondary LASIK) and the technique of corneal flap uncover. The authors evaluate the results of the residual refractive errors using both techniques of reoperaration. The cohort constituted of 74 reoperated eyes of 61 patients. The average age was 29.3 +/- 7.83 years (18 to 48 years) with the average follow-up period of 6.7 +/- 4.7 months (3 to 12 months). The reoperation was performed with the primary refractive error (before the first surgery) less than -3.0 dioptres (D) in 3 eyes, -3.25 to -6.0 D in 24 eyes, and higher than -6 D in 47 eyes of the cohort. Technique of the new incision was chosen in 21 eyes (28.4%) of the cohort (1st group) and corneal flap uncover in 53 eyes (71.6%) (2nd group). The residual refractive error before the reoperation was -1.3 D +/- 0.94 (standard deviation--SD) combined with -1.17 +/- 0.86 (SD) cylindrical dioptres (Dcyl) in the 1st group, and -1.12 D +/- 1.27 (SD) combined with -0.83 Dcyl +/- 0.64 (SD) in the 2nd one. The primary LASIK surgery, as well as reoperation was in all cases performed by argon-fluoride laser, class IV (Keracor 117 Chiron Technolas). The authors evaluated the final postoperative refractive error, reduction of its spherical and cylindrical component, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) the rate of complications during the surgery, and postoperatively as well. The final postoperative refractive error was in the 1st group -0.35 D +/- 0.40 (SD) and -0.56 Dcyl +/- 0.67 (SD), and in the 2nd group -0.17 D +/- 0.36 (SD) and -0.28 Dcyl +/- 0.45 (SD). Reduction of the residual postoperative refractive error after primary LASIK surgery in the spherical part of the error in the new incision technique group was 73.1% (P = 0.01), and in the corneal flap uncover technique 84.8% (P = 0.01). The cylindrical part lowered in the 1st group by 52.1% (P = 0.05), and in the 2nd group by 66% (P = 0.01). Improvement of the uncorrected visual acuity (UCVA) was noticed in the 1st group in 18 eyes (85.7%), and in the 2nd group in 47 eyes (88.7%). The best corrected visual acuity remained in most of the cases unchanged--in the group of the new incision technique in 16 eyes of the cohort, and in the corneal flap uncover technique in 36 eyes (67.9%). Complications during the surgery and after that were noticed in the 1st group in 4 eyes (19%), and in the 2nd group in 12 eyes of the cohort (22.6%). No statistically significant difference in the reduction of the residual refraction error after primary LASIK and complications rate between both mentioned techniques of re-operation were noticed. Both methods may be considered effective and safe.

Adolescent↗
PubMedDate not supplied

Changes in refraction induced by change in intraocular lens position.

BACKGROUND: Intraocular lens (IOL) decentration and tilt may affect postoperative refractive errors through spherical aberration of the IOL. METHODS: Through a use of a ray-tracing program and by minimizing algorithm, we calculated theoretical refractive errors for various degrees of IOL decentration and tilt. We compared our results with those obtained by paraxial vergence calculations. RESULTS: IOL decentration and/or tilt shifted postoperative refractive errors toward myopia and astigmatism of oblique origin. For example, a 3-millimeter decentration of an IOL resulted in induction of approximately -2.00 diopters (D) sphere and +0.70 D cylinder. IOL tilt affected refractive errors to a lesser degree. The change in refractive error caused by a combination of IOL decentration and tilt depended on the relationship between the geometrical axes of decentration and tilt. In the case of the least favorable combination of 12 degrees of tilt and 3 mm of decentration, it can reach -7.00 D sphere and +4.00 D cylinder. CONCLUSIONS: IOL decentration and/or tilt increase myopia and astigmatism. They are negligible for small decentrations, but could be sources of substantial postoperative refractive errors if the decentration or tile is large.

Astigmatism↗
PubMedDate not supplied

Strabismus in Down syndrome.

PURPOSE: To determine the distribution of refractive errors and clinical characteristics of strabismus in patients with Down syndrome. PATIENTS AND METHODS: Patients with Down syndrome attending the Izmir Association for Supporting Patients With Down Syndrome in Izmir, Turkey, were screened for strabismus and refractive errors. All patients underwent a complete eye examination including cycloplegic refraction and dilated fundus examination. Ocular alignment was evaluated using the cover test and either the Krimsky or the Hirschberg corneal reflex test depending on the cooperation of the patient. Strabismic and nonstrabismic patients were compared for refractive errors, anisometropia, and amblyopia. RESULTS: Fifty-seven patients with an average (+/- standard deviation) age of 9.30 years (+/- 6.14 years; range, 1 to 31 years) were screened. Twenty-five (44%) were female and 32 (56%) were male. Eleven patients (19%) had strabismus. Ten (18%) had esotropia and 1 (2%) had exotropia. Infantile esotropia was observed in 3 patients who had no significant refractive errors. Seven patients had acquired esotropia; they had clinically significant refractive errors and anisometropia. A higher frequency of hypermetropia was noted in patients with strabismus (P < .05). CONCLUSIONS: Esotropia and hypermetropia are common in patients with Down syndrome. Early diagnosis and treatment of strabismus and associated ocular conditions such as refractive errors and amblyopia may improve the quality of life for these patients.

Adolescent↗
PubMed2004

Possible association between heavy computer users and glaucomatous visual field abnormalities: a cross sectional study in Japanese workers.

STUDY OBJECTIVE: To study the association between computer use and visual field abnormalities (VFA) and to assess whether heavy computer users have an increased risk of glaucoma. DESIGN: Cross sectional multicentre study. Subjects and observation procedures: A total of 10 202 randomly selected Japanese workers (mean (SD) age 43.2 (9.8) years) were screened for VFA using the frequency doubling technology perimetry (FDT-VFA), in addition to undergoing a general medical check up, and then ophthalmologically examined. Information about their computer use and refractive errors was obtained from a questionnaire and interview, respectively. MAIN RESULTS: As a result of FDT test, 522 and 8602 subjects were positive and negative for FDT-VFA, respectively. A significant (p = 0.004) interaction was found between computer use and refractive errors regarding the risk of FDT-VFA. In stratified analysis, heavy computer users with refractive errors showed a significant positive association with FDT-VFA (odds ratio (OR) = 1.74, 95% confidence interval (CI) 1.28 to 2.37), while those without refractive errors did not. Comparison of 165 subjects with an ophthalmological diagnosis of glaucoma and 2918 controls showed that the OR for glaucoma of heavy computer users with refractive errors was 1.82 (95% CI 1.06 to 3.12). Of 165 subjects with glaucoma, 141 had refractive errors, especially myopia (96.4%, 136 of 141). CONCLUSIONS: Although there are limitations to this study, such as its cross sectional design, heavy computer users with refractive errors seem to have an increased risk of FDT-VFA. Glaucoma might be involved in an underlying disease and myopia in a risk factor for FDT-VFA.

Adult↗
PubMed2006

Accuracy of the WASCA aberrometer refraction compared to manifest refraction in myopia.

PURPOSE: To evaluate the accuracy of myopic refraction by a single measurement using the Wavefront Supported Custom Ablation (WASCA) aberrometer (Carl Zeiss Meditec AG, Jena, Germany). METHODS: We retrospectively compared the refractive errors obtained by manifest refraction and wavefront refraction (WASCA) in 50 eyes of 25 consecutive myopic patients undergoing laser refractive surgery. The sphere ranged from -1.00 to -8.25 diopters (D) and cylinder from 0 to -3.75 D. WASCA measurements under cycloplegia were made and WASCA refractions calculated for a 6-mm analysis zone using the Seidel method within the WASCA. We used the manifest refraction as our best estimate of the true refractive error, therefore accuracy was defined as the difference between manifest refraction and that of the WASCA. Correlation coefficients and mean vector errors between manifest and WASCA refraction were calculated. RESULTS: High correlation was shown between manifest and WASCA refractions, with correlation coefficients (R2) of 0.97, 0.85, and 0.79 for M, J180, and J45, respectively. Mean power vector error (standard deviation) was 0.22 D (0.39), +0.03 D (0.21), and +0.03 D (0.13) for M, J180, and J45, respectively. Total dioptric power vector error was 0.43 D with 74% eyes within 0.50 D. CONCLUSIONS: When measuring normal myopic eyes, the concordance between manifest and WASCA refractions was found on average to be high; however, outlier measurements occurred.

Adult↗
PubMed1995

Myopia in teenagers. An eight-year follow-up study on myopia progression and risk factors.

UNLABELLED: A prospective 2-year study on myopia progression was commenced in 1984/85, with special attention to the rate of progression in a representative group of school children aged 9 to 12 years. A follow-up investigation of this group of myopic persons (now aged 17-20 years) was performed after 8 years, in order to describe the refractive error and possible risk factors for myopia progression over the period. The refractive error increased from -2.77 D to -5.14 D (mean values). PARAMETERS: age at début, degree of myopia, intraocular pressure, changes at the fundus, status of phoria, nearpoint of convergence and accommodation were all measured at the start and related to the refractive error measured 8 years later. No single parameter, apart from age at début, indicated that the individual would reach a high degree of myopia. The refractive error among the children with a début below 7 years of age was -6.60 D, but only -3.72 D among those with a début after 10 years. The change in refractive error over the 8-year period was not statistically related to the age at début, neither did the rate of progression depend on the degree of myopia, the changes at the fundus, nor the intraocular pressure. However, children could be found who had a high rate of progression, by using a combination of these parameters.

Accommodation, Ocular↗
PubMed2000

Peripheral refraction and ocular shape in children.

PURPOSE: To evaluate the relation between ocular shape and refractive error in children. METHODS: Ocular shape was assessed by measuring relative peripheral refractive error (the difference between the spherical equivalent cycloplegic autorefraction 30 degrees in the nasal visual field and in primary gaze) for the right eye of 822 children aged 5 to 14 years participating in the Orinda Longitudinal Study of Myopia in 1995. Axial ocular dimensions were measured by A-scan ultrasonography, crystalline lens radii of curvature by videophakometry, and corneal power by videokeratography. RESULTS: Myopic children had greater relative hyperopia in the periphery (+0.80 +/- 1.29 D), indicating a prolate ocular shape (longer axial length than equatorial diameter), compared with relative peripheral myopia and an oblate shape (broader equatorial diameter than axial length) for emmetropes (-0.41 +/- 0.75 D) and hyperopes (-1.09 +/- 1.02 D). Relative peripheral hyperopia was associated with myopic ocular component characteristics: deeper anterior and vitreous chambers, flatter crystalline lenses that were smaller in volume, and steeper corneas. Lens thickness had a more complex association. Relative peripheral hyperopia was associated with thinner lenses between refractive error groups but changed in sign to become associated with thicker lenses when analyzed within each refractive error group. Receiver operator characteristics analysis of the ocular components indicated that vitreous chamber depth was the most important ocular component for characterizing the myopic eye, but that peripheral refraction made a significant independent contribution. CONCLUSIONS: The eyes of myopic children were both elongated and distorted into a prolate shape. Thinner crystalline lenses were associated with more hyperopic relative peripheral refractions across refractive error groups, but failure of the lens to thin may account for the association between thicker lenses and more hyperopic relative peripheral refractions within a given refractive group. Increased ciliary-choroidal tension is proposed as a potential cause of ocular distortion in myopic eyes.

Adolescent↗
PubMed2006

What is the global burden of visual impairment?

BACKGROUND: A recent estimate by the World Health Organization (WHO) suggests that 161 million persons worldwide have visual impairment, including 37 million blind (best-corrected visual acuity less than 3/60 in the better eye) and 124 million with visual impairment less severe than blindness (best-corrected acuity less than 6/18 to 3/60 in the better eye). This estimate is quoted widely, but because it is based on definitions using best-corrected visual acuity, uncorrected refractive error as a cause of visual impairment is excluded. METHODS: We reviewed data from population-based surveys of visual impairment worldwide published 1996 onwards that included presenting visual acuity, and estimated the proportion of visual impairment caused by uncorrected refractive error in different sub-regions of the world. We then extrapolated these data to estimate the worldwide burden of visual impairment including that caused by uncorrected refractive error. RESULTS: The total number of persons with visual impairment worldwide, including that due to uncorrected refractive error, was estimated as 259 million, 61% higher than the commonly quoted WHO estimate. This includes 42 million persons with blindness defined as presenting visual acuity less than 3/60 in the better eye, and 217 million persons with less severe visual impairment level defined as presenting visual acuity less than 6/18 to 3/60 in the better eye, 14% and 75% higher, respectively, than the WHO estimates based on best-corrected visual acuity. Sensitivity analysis, taking into account the uncertainty of the proportion of visual impairment caused by refractive error, revealed that the number of persons in the world with visual impairment due to uncorrected refractive error could range from 82 to 117 million. CONCLUSION: The actual burden of visual impairment worldwide, including that caused by uncorrected refractive error, is substantially higher than the commonly quoted WHO estimate that is based on best-corrected visual acuity. We suggest that the indicative estimate of 259 million persons with visual impairment worldwide, which includes 42 million blind with visual acuity less than 3/60 in the better eye, be used for further planning of the VISION 2020 initiative instead of the often quoted 161 million estimate that includes 37 million blind.

Cost of Illness↗
PubMed1996

Accuracy and precision of the Tomey ViVA infrared photorefractor.

PURPOSE: The Fortune Optical (Tomey ViVA) VRB-100 video refractor was tested to determine its accuracy and precision in measuring manifest refractions of human eyes with and without cycloplegia. The specific issues addressed included its accuracy in measuring spherical and cylindrical refractive errors and its precision in refracting near emmetropia. METHODS: To determine its ability to measure moderate to high (> 4.00 D) myopia, we compared the VIVA's refractions to those taken by a Canon Autorefractor R1 and a retinoscopist. A spherical lens series from -7.00 to + 7.00 D at 1.00 D intervals, or -5.00 to + 5.00 at 0.50 D intervals, was placed over a subject's eye, which was then covered by an infrared (IR) filter, refracted, and analyzed to determine the VIVA's ability to measure spheres. Subjects with refractive errors of -2.00 to + 2.00 DS (diopters sphere) and 0 to 1.00 DC (diopters cylinder) were refracted 7 to 15 times during 1 sitting to determine the VIVA's precision. The instrument's accuracy in measuring cylinders was tested by placing + 3.00 to -3.00 D cylinders (at 0.50 D intervals) over the eyes of subjects at 0 degree, 45 degrees, 60 degrees, 75 degrees, 90 degrees, 105 degrees, 120 degrees, and 135 degrees. RESULTS: The VIVA measured spheres of +/- 3.00 D with a root mean squared (rms) error of 0.5 +/- 0.1 D. Beyond this power, its accuracy progressively worsened. In some subjects, irregular intensity profiles compromised the VIVA's accuracy even with low spherical refractive errors. The VIVA was very precise in measuring spheres from + 2.00 to -2.00 D and cylinders from 0 to 1.00 D. Although the ViVA adequately measured all cylinder powers at 0 degree and 90 degrees, the accuracy of cylindrical power measurement decreased with obliquity; only cylinders < or = 1.00 D magnitude were accurately measured at 45 degrees and 135 degrees. CONCLUSIONS: We conclude that, although the ViVA offers many attractive features for vision screening, it is seriously limited by its inability to property detect and measure oblique astigmatic errors.

Humans↗
PubMed2002

Myopia in secondary school students in Mwanza City, Tanzania: the need for a national screening programme.

BACKGROUND/AIMS: The prevalence of significant refractive errors and other eye diseases was measured in 2511 secondary school students aged 11-27 years in Mwanza City, Tanzania. Risk factors for myopia were explored. METHODS: A questionnaire assessed the students' socioeconomic background and exposure to near work followed by visual acuity assessment and a full eye examination. Non-cycloplegic objective and subjective refraction was done on all participants with visual acuity of worse than 6/12 in either eye without an obvious cause. RESULTS: 154 (6.1%) students had significant refractive errors. Myopia was the leading refractive error (5.6%). Amblyopia (0.4%), strabismus (0.2%), and other treatable eye disorders were uncommon. Only 30.3% of students with significant refractive errors wore spectacles before the survey. Age, sex, ethnicity, father's educational status, and a family history of siblings with spectacles were significant independent risk factors for myopia. CONCLUSION: The prevalence of uncorrected significant refractive errors is high enough to justify a regular school eye screening programme in secondary schools in Tanzania. Risk factors for myopia are similar to those reported in European, North-American, and Asian populations.

Adolescent↗