Comparisons of the Handheld Autorefractor, Table-Mounted Autorefractor, and Subjective Refraction in Singapore Adults

Comparability of the Retinomax K-plus 3 handheld autorefractometer in quick mode versus on-table autorefractometer in standard mode

INTRODUCTION

This study analyzes the comparability of measurements taken by a Retinomax K-plus 3 handheld autorefractometer in Quick mode and a Topcon KR-800 on-table autorefractometer in standard mode on the pediatric population, and establishes their correlation.

METHODS

It is a retrospective comparative study. Spherical diopter power (SPH), cylindrical diopter power (CYL), angle of cylindrical axis (AX), and spherical equivalent (SE) were measured with the Retinomax in Quick mode and with the Topcon in standard mode. Each patient was evaluated in cycloplegic and non-cycloplegic conditions by both autorefractometers. Student's t-test was performed between the two instruments for SPH, CYL, and SE. The Pearson correlation coefficient was calculated and the dispersion was represented using Bland-Altman graphs, also evaluating the subgroup of patients under 4 years of age. A descriptive analysis of the percentages of measures that differed was performed.

RESULTS

It included 98 eyes of 49 subjects (age range: 3-16 years). The data for HPS without cycloplegia are virtually identical, whereas with cycloplegia there is a hyperopic bias of +0.5 diopters measured with Retinomax. CYL results are very similar with and without cycloplegia. There is a high Pearson correlation for both instruments (>0.91) and a low degree of dispersion in the Bland-Altman plots under cycloplegia.

CONCLUSION

The Retinomax data were consistent with those obtained by Topcon. The Retinomax is a useful instrument for detecting refractive errors in children between 3 and 16 years of age.

Clinical evaluation of autorefraction and subjective refraction with and without cycloplegia in Chinese school-aged children: a cross-sectional study

BACKGROUND

The accuracy of open-field autorefractors is important for vision screening, clinical care, and vision research, especially in patients with childhood myopia. TOPCON KR3000 autorefractor was conventional autorefractor and subjective refraction after cycloplegia was gold criteria for assessing the refraction. Results of refractive error in Chinese school-aged children obtained by three methods were evaluated and compared.

METHODS

A cross-sectional study was conducted. A total of 89 patients (with a total of 177 eyes) diagnosed as refractive error in the Affiliated Hospital of Nanjing University of Chinese Medicine from July 2020 to September 2020 were sequentially enrolled in this study. All subjects underwent routine ophthalmic examination to exclude other ocular diseases and had a best corrected visual acuity no less than 0.1 The spherical diopter (SD), spherical equivalence (SE), and astigmatism (J0 and J45) were determined in patients before cycloplegia using two autorefractors, and again after cycloplegia. Subjective refraction results were obtained simultaneously after cycloplegia as gold criteria for comparison. A comparison of data between three methods was performed using paired t-tests and presented graphically using Bland-Altman plots.

RESULTS

Before cycloplegia, the SD and SE results from WAM were 0.14 D and 0.12 D more positive than the reading from TOPCON (P=0.011 and P=0.021, respectively). The SD measured by WAM and TOPCON was 0.31 D and 0.45 D more negative than the values obtained by subjective refraction after cycloplegia, respectively (P<0.001 and P<0.001, respectively). The SE readings also showed a similar trend (P<0.001, P<0.001). After cycloplegia, the SD and SE measurement obtained with WAM were 0.13 D and 0.12 D more positive than those measured by TOPCON (P<0.001 and P<0.001, respectively), and this was not significantly different to the results obtained using subjective refraction. However, the results of SD, SE, and J0 measured by the TOPCON were significantly different from the results obtained using subjective refraction (P<0.001, P<0.001, and P=0.002, respectively).

CONCLUSIONS

In clinical application, the measurements obtained with the WAM-5500 autorefractor were more reliable than those of the TOPCON KR3000 autorefractor in patients with or without cycloplegia. The WAM-5500 Autorefractor represents a reliable and valid objective refraction tool for optometric practice.

Refractive outcomes of table-mounted and hand-held auto-refractometers in children: an observational cross-sectional study

BACKGROUND

To compare the refractive results of hand-held and table-mounted autorefractors.

METHODS

We designed this study as an observational, cross-sectional study. We compared the mean spheric and cylinder power, spherical equivalent, Jackson cross-cylinder values, determined the limits of agreement (LoA), and evaluated the reliability of two autorefractors.

RESULTS

We evaluated 256 eyes of 256 pediatric patients (mean age, 9.12 ± 2.26 years; range, 5-16 years). 49% of the patients were female, and 51% were male. The Nidek HandyRef-K autorefractor measured relatively more astigmatism (P < 0.001) and less hyperopia (P = 0.024). The mean differences and 95% LoA were 0.06 D ± 0.47 D (- 0.82 D to 0.98 D) in spherical power, 0.08 D ± 0.28 D (- 0.47 D to 0.64 D) in cylindrical power, 0.11 D ± 0.47 D (- 0.81 D to 1.01 D) in spherical equivalent, 0.02 D ± 0.36 D (- 0.73 D to 0.69 D) in Jackson cross-cylinder power at 0°, 0.005 D ± 0.54 D (- 1.07 D to 1.06 D) in Jackson cross-cylinder power at 45°. We found the difference within 0.50 D in 244 (95%) eyes for spherical power, in 245 (96%) eyes for cylindrical power, 228 (89%) eyes for spherical equivalent, 224 (87%) eyes for Jackson cross-cylinder power at 0°, 213 (83%) eyes for Jackson cross-cylinder power at 45°. When comparing devices, there were strong correlations for spherical power (Spearman's rho = 0.99, P < 0.001), cylindrical power (Spearman's rho = 0.88, P < 0.001), and spherical equivalent (Spearman's rho = 0.98, P < 0.001).

CONCLUSION

Two autorefractors showed clinically applicable agreement limits; excellent reliability for spherical power and spherical equivalent and good reliability for cylindrical power; high positive percent agreement for spherical and cylindrical power, spherical equivalent, Jackson cross-cylinder power at 0°and 45°. These results showed that both devices might be used interchangeably for screening of refractive error in children.

Investigation of the Accuracy of a Low-Cost, Portable Autorefractor to Provide Well-Tolerated Eyeglass Prescriptions: A Randomized Crossover Trial

PURPOSE

To compare patient preferences for eyeglasses prescribed using a low-cost, portable wavefront autorefractor versus standard subjective refraction (SR).

DESIGN

Randomized, cross-over clinical trial.

PARTICIPANTS

Patients aged 18 to 40 years presenting with refractive errors (REs) to a tertiary eye hospital in Southern India.

METHODS

Participants underwent SR followed by autorefraction (AR) using the monocular version of the QuickSee device (PlenOptika Inc). An independent optician, masked to the refraction approach, prepared eyeglasses based on each refraction approach. Participants (masked to refraction source) were randomly assigned to use SR- or AR-based eyeglasses first, followed by the other pair, for 1 week each. At the end of each week, participants had their vision checked and were interviewed about their experience with the eyeglasses.

MAIN OUTCOME MEASURES

Patients preferring eyeglasses were chosen using AR and SR.

RESULTS

The 400 participants enrolled between March 26, 2018, and August 2, 2019, had a mean (standard deviation) age of 28.4 (6.6) years, and 68.8% were women. There was a strong correlation between spherical equivalents using SR and AR (r = 0.97, P < 0.001) with a mean difference of -0.07 diopters (D) (95% limits of agreement [LoA], -0.68 to 0.83). Of the 301 patients (75.2%) who completed both follow-up visits, 50.5% (n = 152) and 49.5% (n = 149) preferred glasses prescribed using SR and AR, respectively (95% CI, 45.7-56.3; P = 0.86). There were no differences in demographic or vision characteristics between participants with different preferences (P > 0.05 for all).

CONCLUSIONS

We observed a strong agreement between the prescriptions from SR and AR, and eyeglasses prescribed using SR and AR were equally preferred by patients. Wider use of prescribing based on AR alone in resource-limited settings is supported by these findings.

V. SD, Nagaraj S, Wittberg DM, Stamper RL, Keenan JD. Accuracy of autorefraction in an adult Indian population

Purpose

Autorefractors allow non-specialists to quickly assess refractive error, and thus could be a useful component of large-scale vision screening programs. In order to better characterize the role of autorefraction for public health outreach programs in resource-limited settings, the diagnostic accuracy of two autorefractors was assessed relative to subjective refraction in an adult Indian population.

Methods

An optometrist refracted a series of patients aged ≥50 years at an eye clinic in Bangalore, India using the Nidek ARK-900 autorefractor first, followed by the 3nethra Royal autorefractor, and then subjective refraction. The diagnostic accuracy of each autorefractor for myopia, hyperopia, and astigmatism was assessed using subjective refraction as the reference standard, and measures of agreement between refractions were calculated.

Results

A total of 197 eyes in 104 individuals (mean age 63 ± 8 years, 52% female) were evaluated. Both autorefractors produced spherical equivalent estimates that were on average more hyperopic than subjective refraction, with a measurement bias of +0.16 D (95%CI +0.09 to +0.23D) for Nidek and +0.42 D (95%CI +0.28 to +0.54D) for 3nethra. When comparing pairs of measurements from autorefraction and subjective refraction, the limits of agreement were approximately ±1D for the Nidek autorefractor and ±1.75D for the 3Nethra autorefractor. The sensitivity and specificity of detecting ≥1 diopter of myopia were 94.6% (95%CI 86.8–100%) and 92.5% (95%CI 88.9–97.5%) for the Nidek, and 89.2% (95%CI 66.7–97.4) and 77.5% (95%CI 71.2–99.4%) for the 3Nethra. The accuracy of each autorefractor increased at greater levels of refractive error.

Conclusions

The sensitivity and specificity of the Nidek autorefractor for diagnosing refractive error among adults ≥50 years in an urban Indian clinic was sufficient for screening for visually significant refractive errors, although the relatively wide limits of agreement suggest that subjective refinement of the eyeglasses prescription would still be necessary.

Visual Status in a Portuguese Population with Intellectual Disability

BACKGROUND

Neurosensory deprivation associated with vision is a well-known fact in people with intellectual disability (ID). This work aims to report the visual status of a population with ID in Portugal.

METHODS

A vision screening protocol was conducted during two Special Olympics events. The vision protocol included personal medical history, ocular health evaluation, and clinical measures, such as visual acuity (VA), binocular vision, colour vision, refractive error, and intraocular pressure. This protocol was administered to 134 subjects.

RESULTS

Half of the subjects reported that they had never attended or they did not remember having attended a previous eye exam. Additionally, 10% of them had not attended an eye exam in the immediate past three years. Half the subjects failed the VA test and 13% presented moderate Visual Impairment (VI) (VA worse than 0.5 logMAR in the best eye). Manifest ocular deviation was found in 25% of the subjects and the most common ocular health dysfunction conditions were conjunctiva hyperaemia, meibomian gland dysfunction, and lens anomalies. Refractive error correction allowed a reduction in the level of moderate VI to 3.7%.

CONCLUSIONS

The population analysed showed a poor eye care attendance rate and vision-related conditions are in agreement with previous reports. The development of national strategies to promote the awareness for routine eye care in people with ID and improving accessibility to eye care services may mitigate many of the most prevalent conditions encountered.

Comparison between two autorefractor performances in large scale vision screening in Chinese school age children

AIM

To evaluate the effectiveness of Grand Seiko Ref/Keratometer WAM-5500 compared to Topcon KR800 autorefractor in detecting refractive error in large scale vision screening for Chinese school age children with the WHO criteria.

METHODS

A total of 886 participants were enrolled with mean age of 9.49±1.88y from Tianjin, China. Spherical equivalent (SE) was obtained from un-cycloplegic autorefraction and cycloplegic autorefraction. Topcon KR 800 (Topcon) and Grand Seiko WAM-5500 (WAM) autorefractors were used. Bland-Altman Plot and regression were generated to compare their performance. The overall effectiveness of detecting early stage refractive error was analyzed with receiver operating characteristic (ROC) curves.

RESULTS

The mean SE was -0.98±1.81 diopter (D) and the prevalence of myopia was 48.9% defined by WHO criteria according to the result of cycloplegic autorefraction. The mean SE of un-cycloplegic autorefraction with Topcon and WAM were -1.21±1.65 and -1.20±1.68 D respectively. There was a strong linear agreement between result obtained from WAM and cycloplegic autorefraction with an R² of 0.8318. Bland-Altman plot indicated a moderate agreement of cylinder values between the two methods. The sensitivity and specificity for detecting hyperopia were 90.52% and 83.51%; for detecting myopia were 95.60% and 90.24%; for detecting astigmatism were 79.40% and 90.21%; for detecting high myopia were 98.16% and 98.91% respectively.

CONCLUSION

These findings suggest that both Grand Seiko and Topcon autorefractor can be used in large-scale vision screening for detecting refractive error in Chinese population. Grand Seiko gives relatively better performance in detecting myopia, hyperopia, and high myopia for school age children.

Repeatability of ARK-30 in a pediatric population

Purpose:

To determine repeatability and agreement of the ARK-30 handheld autorefractor with retinoscopy under cycloplegic and noncycloplegic conditions in children.

Methods:

Three consecutive autorefractor measurements (with and without cycloplegia) and retinoscopy were performed and compared in 30 randomized eyes of 30 children (mean age of 6.7 ± 2.7 years with spherical equivalent [SE] refraction from ‒4.01 to +7.38 D) in a cross-section and masked study. Bland–Altman analysis of autorefractor measurements (with and without cycloplegia) and agreement with retinoscopy were calculated with conventional notation (sphere [Sph] and cylinder [Cyl]) and vector notation (SE, J₀, and J₄₅ coefficients).

Results:

ARK-30 measurements without cycloplegia were lower than under cycloplegic conditions (Sph: ‒0.52 ± 2.37 D vs + 0.86 ± 2.60 D, P < 0.01; Cyl: ‒0.83 ± 0.80 D versus ‒0.78 ± 0.77 D, P = 0.37; and SE: ‒0.94 ± 2.19 D vs + 0.47 ± 2.44 D, P < 0.01, respectively) and statistically different (P < 0.03) from retinoscopy (Shp: +0.83 ± 2.66 D; Cyl: ‒0.71 ± 0.87 D; SE: +0.51 ± 2.49 D). Without statistical differences were in J₀ and J₄₅ coefficients. Cyloplegic autorefraction measures were not found to be statistically significantly different to retinoscopy measures. ARK-30 under cycloplegia shows better repeatability with lower limits of agreement (LoA) in Sph (LoA: ‒0.66 to +0.69 D), and SE (LoA: ‒0.66 to +0.65 D) than without cycloplegia (LoA: ‒1.45 to +1.77 D, and ‒1.38 to +1.74 D, respectively).

Conclusion:

Under noncycloplegic conditions, ARK-30 autorefractor has low repeatability and a tendency toward minus over correction in children. However, repeatability and agreement with retinoscopy under cycloplegic conditions allow use of ARK-30 in children to estimate refraction but not to substitute gold standard retinoscopic refraction.

Monitoring and Morphologic Classification of Pediatric Cataract Using Slit-Lamp-Adapted Photography

Purpose

To investigate the feasibility of pediatric cataract monitoring and morphologic classification using slit lamp–adapted anterior segmental photography in a large cohort that included uncooperative children.

Methods

Patients registered in the Childhood Cataract Program of the Chinese Ministry of Health were prospectively selected. Eligible patients underwent slit-lamp adapted anterior segmental photography to record and monitor the morphology of their cataractous lenses. A set of assistance techniques for slit lamp–adapted photography was developed to instruct the parents of uncooperative children how to help maintain the child's head position and keep the eyes open after sleep aid administration.

Results

Briefly, slit lamp–adapted photography was completed for all 438 children, including 260 (59.4%) uncooperative children with our assistance techniques. All 746 images of 438 patients successfully confirmed the diagnoses and classifications. Considering the lesion location, pediatric cataract morphologies could be objectively classified into the seven following types: total; nuclear; polar, including two subtypes (anterior and posterior); lamellar; nuclear combined with cortical, including three subtypes (coral-like, dust-like, and blue-dot); cortical; and Y suture. The top three types of unilateral cataracts were polar (55, 42.3%), total (42, 32.3%), and nuclear (23, 17.7%); and the top three types of bilateral cataracts were nuclear (110, 35.8%), total (102, 33.2%), and lamellar (34, 11.1%).

Conclusions

Slit lamp–adapted anterior segmental photography is applicable for monitoring and classifying the morphologies of pediatric cataracts and is even safe and feasible for uncooperative children with assistance techniques and sleep aid administration.

Translational Relevance

This study proposes a novel strategy for the preoperative evaluation and evidence-based management of pediatric ophthalmology (Clinical Trials.gov, NCT02748031).

Usefulness of refractive measurement of wavefront autorefraction in patients with difficult retinoscopy

PURPOSE

To assess the ability of the WaveScan WaveFront System (VISX Inc, Santa Clara, CA) to measure refractive errors in patients with difficult retinoscopy and to compare results to standard cycloplegic retinoscopy.

METHODS

The medical records of patients with an ocular condition that could contribute to difficult or unreliable retinoscopy who underwent nondilated, noncycloplegic evaluation with the WaveScan WaveFront System were reviewed retrospectively. Results were compared to a standard cycloplegic retinoscopy.

RESULTS

A total of 60 eyes of 31 patients were included. Wavefront sphere, cylinder, and spherical equivalent measurements were strongly correlated with retinoscopy results; however, the wavefront measured more myopia and more cylinder compared to standard retinoscopy.

CONCLUSIONS

Wavefront can be used to augment and enhance cycloplegic streak retinoscopy.

Autorefraction, Retinoscopy, Javal's Rule, and Grosvenor's Modified Javal's Rule: The Best Predictor of Refractive Astigmatism

The aim of the study was to determine the level of agreement between Javal's rule, autorefraction, retinoscopy, and refractive astigmatism and to determine which technique is the most suitable substitute when subjective refraction is not applicable using a clinical sample. A total of 36 subjects, 14 males and 22 females, were involved in this study. The intraclass correlation coefficients between subjective refraction, autorefraction, and retinoscopy were 0.895 and 0.989, respectively, for the spherical equivalent. The Bland-Altman 95% limits of agreement between subjective refraction and autorefraction; subjective refraction and retinoscopy; and autorefraction and retinoscopy were −2.84 to 3.58, −0.88 to 1.12, and −3.01 to 3.53, respectively, for the spherical equivalent. The intraclass correlation coefficients between spectacle total astigmatism and the following techniques were as follows: retinoscopy (0.85); autorefraction (0.92); Javal's rule (0.82); and Grosvenor et al. version (0.85). The Bland-Altman 95% limits of agreement between subjective refraction and autorefraction; subjective refraction and retinoscopy; subjective refraction and Javal's rule; and subjective refraction and Grosvenor et al. version were −0.87 to 1.25, −1.49 to 1.99, −0.73 to 1.93, and −0.89 to 1.7, respectively, for the total astigmatism. The study showed that autorefraction and Javal's rule may provide a starting point for subjective refraction cylinder power determination but only retinoscopy may satisfactorily replace subjective refraction total astigmatism when subjective refraction is not applicable.

Cycloplegic autorefraction versus subjective refraction: the Tehran Eye Study

AIM

To compare cycloplegic autorefraction with non-cycloplegic subjective refraction across all age and refractive error groups.

METHODS

In a cross-sectional study with random stratified cluster sampling, 160 clusters were chosen from various districts proportionate to the population of each district in Tehran. Following retinoscopy and autorefraction with the 0.25 D bracketing (Topcon KR-8000, Topcon, Tokyo, Japan), all participants had a subjective refraction. Then all participants underwent cycloplegic autorefraction.

RESULTS

The final analysis was performed on 3482 participants with a mean age of 31.7 years (range 5-92 years). Based on cycloplegic and subjective refraction, mean spherical equivalent (SE) was +0.31±1.80 and -0.32±1.61 D, respectively (p<0.001). The 95% limits of agreement (LoA) between these two types of refraction were from -0.40 to 1.70 D. The largest difference between these two types of refraction was seen in the age group of 5-10 years (1.11±0.60 D), and the smallest difference was in the age group of >70 years (0.34±0.45 D). The 95% LoA was -0.52 to 0.89 D in patients with myopia and -0.12 to 2.04 D in patients with hyperopia. We found that female gender (coefficients=0.048), older age (coefficients=-0.247), higher education (coefficients=-0.043) and cycloplegic SE (coefficients=-0.472) significantly correlated with lower intermethod differences.

CONCLUSIONS

The cycloplegic refraction is more sensitive than the subjective one to measure refractive error at all age groups especially in children and young adults. The cyclorefraction technique is highly recommended to exactly measure the refractive error in momentous conditions such as refractive surgery, epidemiological researches and amblyopia therapy, especially in hypermetropic eyes and paediatric cases.

Comparison of the refractive measurements with hand-held autorefractometer, table-mounted autorefractometer and cycloplegic retinoscopy in children

Purpose

To evaluate the performance of the hand-held and table-top autorefractokeratometer in measuring refractive errors by comparing them with cycloplegic retinoscopy.

Methods

Included in the study were 112 eyes of 112 pediatric patients whose mean age was 6.78 ± 2.61 years (range, 2 to 12 years). The refractive errors of all the eyes were measured with and without cycloplegia using a hand held autorefractokeratometer (Retinomax K-plus 3), table top autorefractokeratometer (Canon RK-F1) and performing cycloplegic retinoscopy. The spherical equivalent, cylindrical axis and keratometer values were statistically compared.

Results

The mean spherical equivalent obtained from the Retinomax K-plus 3 was significantly less hyperopic than that of Canon RK-F1 (p = 0.004) before cycloplegia. When the Bland Altman analysis was performed in comparisons of spherical equivalent values measured with the Retinomax K-plus 3, Canon RK-F1 and cycloplegic retinoscopy, it was seen that almost all of the differences between the measurements remained within the range of ±2 standard deviation. Good agreement was found between Retinomax K-plus 3 and Canon RK-F1 for the Jackson cross-cylinder values at axis 0° and 45°; keratometer values respectively.

Conclusions

The refractive error components were highly correlated between the two instruments and cycloplegic retinoscopy.

Comparison of the Retinomax hand-held autorefractor versus table-top autorefractor and retinoscopy

AIM

To compare noncycloplegic and cycloplegic results of Retinomax measurements with findings achieved after cycloplegia using table-top autorefractor and retinoscopy.

METHODS

The study included 127 patients (mean age 96.7mo, range 21 to 221). Retinomax (Rmax) (Nikon Inc., Japan) was used to obtain noncycloplegic refraction. Under cycloplegia, refraction was measured with Rmax, table-top autorefractor (TTR) (Nikon NRK 8000, Inc., Japan) and retinoscopy. The values of sphere, spherical equivalent, cylinder and axis of cylinder were recorded for Rmax, TTR and retinoscopy in each eye. All results were analyzed statistically.

RESULTS

THE MEAN SPHERIC VALUES (SV), SPHERICAL EQUIVALENT VALUES (SEV) AND CYLINDRICAL VALUES (CV) OF THE NONCYCLOPLEGIC RMAX (SV: 0.64 D, SEV: 0.65 D and CV: 0.03 D, respectively) were found to be significantly lower than cycloplegic TTR (1.43 D, 1.38 D and 0.3 D; P=0.012, P=0.011 and P=0.04, respectively) and retinoscopy (1.34 D, 1.45 D and 0.23 D; P=0.04, P=0.002 and P=0.045, respectively). Mean cycloplegic SV, SEV, CV were not significantly different between Rmax and TTR, Rmax and retinoscopy, TTR and retinoscopy. Cycloplegic or noncycloplegic axis values were not different between any method.

CONCLUSION

Rmax may be used successfully as a screening tool but may not be accurate enough for actual spectacle prescription. Cycloplegic Rmax measurements may be able to identify refractive error in children because of approximate results to retinoscopy.

Refractive errors in 3-6 year-old Chinese children: a very low prevalence of myopia?

Purpose

To examine the prevalence of refractive errors in children aged 3–6 years in China.

Methods

Children were recruited for a trial of a home-based amblyopia screening kit in Guangzhou preschools, during which cycloplegic refractions were measured in both eyes of 2480 children. Cycloplegic refraction (from 3 to 4 drops of 1% cyclopentolate to ensure abolition of the light reflex) was measured by both autorefraction and retinoscopy. Refractive errors were defined as followed: myopia (at least −0.50 D in the worse eye), hyperopia (at least +2.00 D in the worse eye) and astigmatism (at least 1.50 D in the worse eye). Different definitions, as specified in the text, were also used to facilitate comparison with other studies.

Results

The mean spherical equivalent refractive error was at least +1.22 D for all ages and both genders. The prevalence of myopia for any definition at any age was at most 2.5%, and lower in most cases. In contrast, the prevalence of hyperopia was generally over 20%, and declined slightly with age. The prevalence of astigmatism was between 6% and 11%. There was very little change in refractive error with age over this age range.

Conclusions

Previous reports of less hyperopic mean spherical equivalent refractive error, and more myopia and less hyperopia in children of this age may be due to problems with achieving adequate cycloplegia in children with dark irises. Using up to 4 drops of 1% cyclopentolate may be necessary to accurately measure refractive error in paediatric studies of such children. Our results suggest that children from all ethnic groups may follow a similar pattern of early refractive development, with little myopia and a hyperopic mean spherical equivalent over +1.00 D up to the age of 5–6 yearsin most conditions.

Non-cycloplegic spherical equivalent refraction in adults: comparison of the double-pass system, retinoscopy, subjective refraction and a table-mounted autorefractor

AIM

To evaluate the accuracy of spherical equivalent (SE) estimates of a double-pass system and to compare it with retinoscopy, subjective refraction and a table-mounted autorefractor.

METHODS

Non-cycloplegic refraction was performed on 125 eyes of 65 healthy adults (age 23.5±3.0 years) from October 2010 to January 2011 using retinoscopy, subjective refraction, autorefraction (Auto kerato-refractometer TOPCON KR-8100, Japan) and a double-pass system (Optical Quality Analysis System, OQAS, Visiometrics S.L., Spain). Nine consecutive measurements with the double-pass system were performed on a subgroup of 22 eyes to assess repeatability. To evaluate the trueness of the OQAS instrument, the SE laboratory bias between the double-pass system and the other techniques was calculated.

RESULTS

The SE mean coefficient of repeatability obtained was 0.22D. Significant correlations could be established between the OQAS and the SE obtained with retinoscopy (r=0.956, P<0.001), subjective refraction (r=0.955, P<0.001) and autorefraction (r=0.957, P<0.001). The differences in SE between the double-pass system and the other techniques were significant (P<0.001), but lacked clinical relevance except for retinoscopy; Retinoscopy gave more hyperopic values than the double-pass system -0.51±0.50D as well as the subjective refraction -0.23±0.50D; More myopic values were achieved by means of autorefraction 0.24±0.49D.

CONCLUSION

The double-pass system provides accurate and reliable estimates of the SE that can be used for clinical studies. This technique can determine the correct focus position to assess the ocular optical quality. However, it has a relatively small measuring range in comparison with autorefractors (-8.00 to +5.00D), and requires prior information on the refractive state of the patient.

Trial frame refraction versus autorefraction among new patients in a low-vision clinic

PURPOSE

To determine the relationship between refractive error as measured by autorefraction and that measured by trial frame refraction among a sample of adults with vision impairment seen in a university-based low-vision clinic and to determine if autorefraction might be a suitable replacement for trial frame refraction.

METHODS

A retrospective chart review of all new patients 19 years or older seen over an 18-month period was conducted and the following data collected: age, sex, primary ocular diagnosis, entering distance visual acuity, habitual correction, trial frame refraction, autorefraction, and distance visual acuity measured after trial frame refraction. Trial frame refraction and autorefraction were compared using paired t-tests, intraclass correlations, and Bland-Altman plots.

RESULTS

Final analyses included 440 patients for whom both trial frame refraction and autorefraction data were available for the better eye. Participants were mostly female (59%) with a mean age of 68 years (SD = 20). Age-related macular degeneration was the most common etiology for vision impairment (44%). Values for autorefraction and trial frame refraction were statistically different, but highly correlated for the spherical equivalent power (r = 0.92), the cylinder power (r = 0.80) and overall blurring strength (0.89). Although the values of the cross-cylinders J(0) and J(45) were similar, they were poorly correlated (0.08 and 0.15, respectively). The range of differences in spherical equivalent power was large (-8.6 to 4.9).

CONCLUSIONS

Autorefraction is highly correlated with trial frame refraction. Differences are sometimes substantial, making autorefraction an unsuitable substitute for trial frame refraction.

A comparison of different autorefractors with retinoscopy in children

PURPOSE

To compare the results of different refractive error measurement devices including table-mounted and hand-held autorefractors and videoretinoscopy with cycloplegic retinoscopy (CR) in children to evaluate the usability and reliability of these devices in measuring refractive errors.

METHODS

Two hundred eyes of 100 children underwent autorefraction using table-mounted autorefractor with and without cycloplegia and videoretinoscopy after cycloplegia. All results were compared statistically.

RESULTS

The mean spheric values (SV) and spherical equivalent values (SEV) of the non-cycloplegic table-mounted autorefractor were found to be significantly lower and those of the cycloplegic table-mounted autorefractor were found to be significantly higher than CR results. There was no statistically significant difference in terms of mean SV and SEV between the hand-held autorefractor and CR. Although the mean SV using videoretinoscopy were 0.15 diopters lower than CR, this difference was not significant. Comparing CR with the other refraction methods, all devices correlated with each other. Sensitivity in diagnosing myopia was low for all methods but sensitivity in diagnosing hyperopia and astigmatism was high for table-mounted and hand-held autorefractors. The other reliability parameters were found to be similar for all devices.

CONCLUSIONS

Both videoretinoscopy and hand-held autorefractor can be used in both screening and examination for children as an alternative to CR and table-mounted autorefractor.

Used glasses versus ready-made spectacles for the treatment of refractive error

BACKGROUND AND OBJECTIVE

To compare visual outcomes for used glasses versus ready-made spectacles in the treatment of refractive error.

PATIENTS AND METHODS

In this prospective, comparative case series, undilated refractive error screening examinations were conducted over a 5-week period. Patients with bilateral refractive error were treated with used glasses and ready-made spectacles powered to match their prescriptions. Snellen visual acuity was measured with no correction, best (manifest) correction, unrefined autorefraction, used glasses, and ready-made spectacles. Main outcome measurements were the mean visual improvement from uncorrected acuity and median final visual acuity after treatment with used and ready-made spectacles.

RESULTS

One hundred forty-one patients ages 18 and older with bilateral refractive error were examined. Uncorrected visual acuity in each eye improved an average of 4.5 lines with best correction, 4.0 lines with used glasses, and 3.5 lines with ready-made spectacles, with used glasses demonstrating a statistically significant advantage over ready-made spectacles (P < .001). The median visual acuity in the better eye improved from 20/60 uncorrected to 20/25 with all types of glasses. In patients with less than 1 diopter of anisometropia and greater than 1 diopter of astigmatism in each eye (49%), the ready-made spectacles performed equally as well as the used glasses (P = .95), improving vision an average of 3.9 lines for a median final visual acuity of 20/25 in the better eye.

CONCLUSION

Although both were effective, used glasses are better than ready-made spectacles for improving vision loss due to refractive error.

Treating uncorrected refractive error in adults in the developing world with autorefractors and ready-made spectacles

BACKGROUND

To evaluate a method for treating uncorrected refractive error in adults in the developing world.

DESIGN

Prospective, cross-sectional study in outpatient community health centres.

PARTICIPANTS

Eight hundred and forty subjects aged 18 and older from rural villages in Haiti and Belize.

METHODS

Undilated refractive error screening exams were conducted over a 5-day period in rural Haiti and Belize using portable autorefractors. Isometropic, spherical, ready-made spectacles were provided to patients with bilateral refractive error, astigmatism ≤ 1 dioptre in each eye and visual acuity worse than 6/9 in each eye. Visual acuity was measured with and without corrective spectacles.

MAIN OUTCOME MEASURES

  The mean visual improvement and median final visual acuity after treatment with ready-made glasses.

RESULTS

Eight hundred and forty patients aged 18 and older were screened with autorefractors. One hundred and eighty-nine subjects (22.5%) were found to have visually significant bilateral refractive error. Fifty-eight per cent (110/189) of these patients met criteria for treatment with ready-made spectacles. Visual acuity improved an average of 4.2 lines in the better eye and 4.1 lines in the worse eye with corrective glasses. The median visual acuity in the better eye was 6/6 after treatment.

CONCLUSION

Autorefractors and ready-made spectacles allow for effective treatment of uncorrected refractive error in adults in the developing world.

Testability of vision and refraction in preschoolers: the strabismus, amblyopia, and refractive error study in singaporean children

PURPOSE

To determine the testability of several vision and refraction tests in preschool-aged children.

DESIGN

Population-based study of Chinese preschool-aged children in Singapore.

METHODS

One thousand five hundred and forty-two Singaporean Chinese children aged 6 to 72 months were recruited through door-to-door screening of government-subsidized apartments in Singapore. Trained eye professionals administered all tests, including monocular logarithm of the minimum angle of resolution visual acuity with the Sheridan Gardiner chart, monocular Ishihara color testing (Richmond Products Inc, Albuquerque, New Mexico, USA), biometric measurements using IOLMaster (Carl Zeiss, Jena, Germany), and Randot stereoacuity (Stereo Optical Co, Chicago, Illinois, USA) for children 30 to younger than 72 months. Cycloplegic refraction and keratometry measurements also were determined using a table-mounted autorefractor (Canon Autorefractor RK-F1; Canon, Tokyo, Japan) in children 24 to younger than 72 months.

RESULTS

Testabilities were 84.8% for visual acuity (40.7% for age 30 to < 36 months, 70.8% for age 36 to < 42 months, 86.7% for age 42 to < 48 months, 94.8 for age 48 to < 54 months, 98.6 for age 54 to < 66 months, and 98.7% for age 66 to < 72 months), 81.1% for the Ishihara color test, 82.2% for Randot stereoacuity, 62.2% for table mounted autorefraction, and 91.7% for IOLMaster. All testabilities significantly increased with age (P < .0001). Girls had higher testability rates than boys for the autorefraction and Randot stereoacuity tests (P = .036 and .008, respectively).

CONCLUSIONS

The vision and refraction tests were testable in a high proportion of preschool-aged Chinese Singaporeans. Preschool children in older age groups are likely to complete these tests successfully, with important implications for determining age limits for screening in the community and clinic.

Theoretical evaluation of the cataract extraction-refraction-implantation techniques for intraocular lens power calculation

PURPOSE

To evaluate theoretically three previously published formulae that use intra-operative aphakic refractive error to calculate intraocular lens (IOL) power, not necessitating pre-operative biometry. The formulae are as follows: IOL power (D) = Aphakic refraction x 2.01 [Ianchulev et al., J. Cataract Refract. Surg.31 (2005) 1530]; IOL power (D) = Aphakic refraction x 1.75 [Mackool et al., J. Cataract Refract. Surg.32 (2006) 435]; IOL power (D) = 0.07x(2) + 1.27x + 1.22, where x = aphakic refraction [Leccisotti, Graefes Arch. Clin. Exp. Ophthalmol.246 (2008) 729].

METHODS

Gaussian first order calculations were used to determine the relationship between intra-operative aphakic refractive error and the IOL power required for emmetropia in a series of schematic eyes incorporating varying corneal powers, pre-operative crystalline lens powers, axial lengths and post-operative IOL positions. The three previously published formulae, based on empirical data, were then compared in terms of IOL power errors that arose in the same schematic eye variants.

RESULTS

An inverse relationship exists between theoretical ratio and axial length. Corneal power and initial lens power have little effect on calculated ratios, whilst final IOL position has a significant impact. None of the three empirically derived formulae are universally accurate but each is able to predict IOL power precisely in certain theoretical scenarios. The formulae derived by Ianchulev et al. and Leccisotti are most accurate for posterior IOL positions, whereas the Mackool et al. formula is most reliable when the IOL is located more anteriorly.

CONCLUSION

Final IOL position was found to be the chief determinant of IOL power errors. Although the A-constants of IOLs are known and may be accurate, a variety of factors can still influence the final IOL position and lead to undesirable refractive errors. Optimum results using these novel formulae would be achieved in myopic eyes.

Ethnicity-specific prevalences of refractive errors vary in Asian children in neighbouring Malaysia and Singapore

AIM

To compare the prevalences of refractive errors in Malay, Chinese and Indian children in Malaysia and Singapore.

METHODS

Children aged 7-9 years from three schools in the Singapore Cohort study of the Risk factors for Myopia (n = 1962) and similarly aged children from a random cluster sample in the metropolitan Kuala Lumpur area in the Malaysia Refractive Error Study in Children (n = 1752) were compared. Cycloplegic autorefraction was conducted in both countries.

RESULTS

The prevalence of myopia (spherical equivalent of at least -0.5 diopters (D) in either eye) was higher in Singapore Malays (22.1%) than in Malays in Malaysia (9.2%; 95% confidence interval (CI) 11.2 to 14.7; p<0.001). Similarly, Singapore Chinese (40.1%) had higher prevalences than Malaysian Chinese (30.9%; 95% CI 1.5 to 16.9). Singapore Indians had a higher prevalence (34.1%) than Malaysian Indians (12.5%; 95% CI 17.4 to 25.9). The multivariate odds ratio of astigmatism (cylinder at least 0.75 D in either eye) in Singapore Malays compared with Malaysian Malays was 3.47 (95% CI 2.79 to 4.32). Ethnicity-specific hyperopia rates did not differ in Singapore and Malaysia.

CONCLUSION

The ethnicity-specific prevalences of myopia in Singapore Malays, Chinese and Indians are higher than those in Malaysian Malays, Chinese and Indians. As Malays, Chinese and Indians in Malaysia have genetic make-up similar to that of Malays, Chinese and Indians in Singapore, environmental factors may contribute to the higher myopia rates.