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PubMed2005

The influence of cycloplegia in objective refraction.

The purpose of this study was to compare refractions measured with an autorefractor and by retinoscopy with and without cycloplegia. The objective refractions were performed in 199 right eyes from 199 healthy young adults with a mean age of 21.6 +/- 2.66 years. The measurements were performed first without cycloplegia and repeated 30 min later with cycloplegia. Data were analysed using Fourier decomposition of the power profile. More negative values of component M and J(0) were given by non-cycloplegic autorefraction compared with cycloplegic autorefraction (p < 0.0001). However more positive values for the J(45) vector were given by non-cycloplegic autorefraction, although this difference was not statistically significant (p = 0.233). By retinoscopy, more negative values of component M were obtained with non-cycloplegic retinoscopy (p < 0.0001); for the cylindrical vectors J(0) and J(45) the retinoscopy without cycloplegia yields more negative values (p = 0.234; p = 0.112, respectively). Accepting that differences between cycloplegic and non-cycloplegic retinoscopy are only due to the accommodative response, the present results confirm that when performed by an experienced clinician, retinoscopy is a more reliable method to obtain the objective starting point for refraction under non-cycloplegic conditions.

Accommodation, Ocular↗
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

[Accuracy of the autorefractor power refractor in clinical work--a comparative study].

BACKGROUND: The aim of this prospective study was to investigate accuracy and efficiency of the autorefractometer PowerRefractor compared to established autorefractometers and retinoscopy as standard method. PATIENTS AND METHODS: 150 patients (300 eyes) were examined. Patients were initially (pupil not influenced) analyzed with the Power Refractor (PR (neutral)). After that a examination followed under standardized Cyclopentolat cycloplegia with the Power Refractor (PR (cyclo)), the hand-held Retinomax K-plus (Nikon), the table-top mounted RK-5 (Canon) and retinoscopy. RESULTS: Deviation from retinoscopy (percentage of values with more than 1 dpt difference/maximal deviation): Sphere: PR (neutral): 66.3 %/8.5 dpt; PR (cyclo): 48 %/5 dpt; RK-5: 26.7 %/4.75 dpt; Retinomax K-plus: 6.7 %/1.25 dpt; Cylinder: PR (neutral): 12 %/6.25 dpt; PR (cyclo): 21 %/4.75 dpt; RK-5: 1.3 %/2.75 dpt; Retinomax K-plus: 2.3 %/2.5 dpt; spherical equivalent: PR (neutral): 44.7 %/7.1 dpt; PR (cyclo): 35.3 %/5.4 dpt; RK-5: 9 %/4.5 dpt; Retinomax K-plus: 1.3 %/1.,4 dpt; error of entire refraction: PR (neutral): 62.7 %/7.8 dpt; PR (cyclo): 61.3 %/7.3 dpt; RK-5: 24 %/4,5 dpt; Retinomax K-plus: 14.7 %/3.6 dpt CONCLUSIONS: The best accuracy compared to retinoscopy had Retinomax K-plus followed by RK-5. PowerRefractor had the biggest deviations of the tested devices. PowerRefractor may be a usefull device for screening small children and handicapped people because of the one meter observing distance. For a precise refraction especially in children a retinoscopy under cycloplegic conditions is still necessary.

Adolescent↗
PubMed2003

Refractive state of tree shrew eyes measured with cortical visual evoked potentials.

PURPOSE: To determine the refractive state of tree shrew eyes using visual evoked potentials (VEP's) recorded from primary visual cortex and compare the values with those obtained with streak retinoscopy and with an autorefractor. METHODS: VEP's were recorded in seven normal tree shrews and three animals in which approximately 5 D of myopia (relative to control eye) was induced by monocular -5 D lens wear. While the animals were awake, refractive correction was measured with an autorefractor before and after cycloplegia (1% atropine and 2.5% phenylepherine). When anesthetized, cycloplegic refractive correction was measured with streak retinoscopy. Then VEP's were produced with square-wave counterphased (1 Hz) high-contrast checkerboard patterns near the animals' high spatial frequency cutoff. Spherical lenses (2 D steps) were placed before the eye, and the VEP (average of 128 sweeps) was measured to determine the lens that produced the largest first positive peak (P1). RESULTS: VEP's were obtained over a broad range of trial lenses. Tuning was narrower when check sizes were small. In normal and control eyes, the P1 amplitude was largest, on average, for a trial lens of (mean +/- SD) -0.6 +/- 1.6 D (corrected for working distance but not vertex distance). The mean streak retinoscopy value (spherical equivalent at the corneal plane) was 7.0 +/- 0.8 D, and mean autorefractor values were 4.0 +/- 1.1 D (cycloplegic) and 3.7 +/- 1.2 D (noncycloplegic). In the eyes that compensated for a -5 D lens, the largest P1 values occurred with lenses with a power of -6.3 +/- 3.2 D. Thus, the VEP measure showed a similar treated vs. control eye difference as did streak retinoscopy (treated eyes, 4.7 +/- 0.4 D myopic) and the autorefractor (treated eyes, 4.8 +/- 0.5 D myopic). CONCLUSIONS: Normal tree shrew eyes are approximately emmetropic. The hyperopic values obtained with streak retinoscopy and the autorefractor are consistent with the presence of a "small-eye artifact" in tree shrews. Eyes that have compensated for a -5 D lens are myopic by approximately the value of the lens.

Animals↗
PubMed1997

[Intraoperative skiascopy for determining the refractive value of an implantable intraocular lens].

BACKGROUND: Preoperative biometry for calculation of the refractive power of intraocular lenses is not sufficiently reliable in certain cases. Most frequently inaccuracies tend to occur in highly myopic eyes. Preceding refractive procedures can also impair IOL-calculation or even make it impossible. PATIENTS: In a highly myopic patient IOL-power calculation was not possible with conventional calculation formulas due to a preexisting refractive silicone lens located between the cataractuous natural lens and the iris. In another myopic patient ultrasound measurement of axial eye length produced variable and unreliable results. Therefore retinoscopy was performed intraoperatively in the aphakic eye. Refractive power of the IOL was calculated using a new formula. For validation of the method retinoscopy was performed intraoperatively in a second group of 11 patients with unproblematic ultrasound biometry. RESULTS: In 3 eyes IOL power was chosen according to intraoperative retinoscopy. A maximal deviation of 1.25 D from the aimed refraction resulted. In the second group, the retinoscopic method produced partially considerably inaccurate results as compared to the ultrasound biometry. Inaccuracies increased with the extent of hyperopia. CONCLUSIONS: In cases of difficult or inaccurate preoperative ultrasound biometry IOL power can be estimated after intraoperative retinoscopy in the aphacic highly myopic eye. IOL power can be calculated instantly using computer programs or tables. This method additionally enables the surgeon to control the refractive result of intraocular lens implantation prior to wound closure. However this method lacks reliability in higher hyperopic eyes, as in these cases small changes in corneal vertex distance of the lens used for retinoscopy highly alter the result.

Adult↗
PubMed1996

Comparison of clinical techniques to assess the near accommodative response.

Assessment of the accommodative response (AR) is an essential part of the optometric examination. This study compared a number of clinical procedures for determining the AR with the findings of an objective infrared autorefractor. First, the AR to a 2.5 D binocular stimulus was measured by dynamic retinoscopy (neutralization being obtained both with lenses and by varying the working distance), dynamic cross-cylinder (with and without fogging lenses), and a near red-green duochrome test. Second, the response to a monocular 2.5 D stimulus was examined using dynamic retinoscopy (neutralizing with lenses), dynamic cross-cylinder, and the red-green duochrome. Third, the monocular AR was examined with both red-green and blue-yellow near duochrome tests. Under binocular conditions, the mean ARs for all the tests were clinically equivalent. However, comparison with the findings from the objective autorefractor indicated that dynamic retinoscopy (where neutralization was obtained by varying the working distance) showed the closest agreement, whereas the two dynamic cross-cylinder procedures exhibited the greatest variability. For the monocular condition, the mean lag of accommodation observed with the autorefractor was significantly less than that observed with dynamic retinoscopy, the dynamic cross-cylinder, or the red-green duochrome. However, the blue-yellow near duochrome test did not provide a valid estimation of the AR. It is concluded that the technique of dynamic retinoscopy where the working distance is varied to obtain a neutral reflex should be the method of choice for the clinical assessment of the AR, because this procedure does not require the introduction of supplementary lenses, which may themselves alter the AR.

Accommodation, Ocular↗
PubMed2003

Cycloplegic autorefraction results in pre-school children using the Nikon Retinomax Plus and the Welch Allyn SureSight.

PURPOSE: Early detection and treatment of amblyogenic conditions such as high refractive errors and anisometropia can help prevent the development of amblyopia. The traditional gold standard for the determination of refractive error in pre-school children is retinoscopy. Difficulties with retinoscopy in pre-school children have led to the development of autorefractors that can be free of operator bias and can be used by lay individuals. The Nikon Retinomax Plus handheld autorefractor has proven to be reliable for quick and accurate assessments of refractive errors in children. The Welch Allyn SureSight Vision Screener is a relatively new handheld autorefractor. The present study compares the results of measurements with the Retinomax Plus and the SureSight to the results of cycloplegic retinoscopy in pre-school children. METHODS: Thirty-five children ranging in age from 3 to 5 years old were subjects. Any subjects with strabismus, amblyopia, nystagmus, or ocular disease were excluded. Refractive error was assessed 30 min after the application of a cycloplegic spray. RESULTS: Both autorefractors showed moderate agreement with cycloplegic retinoscopy results for measurement of spherical equivalent and cylinder power. In addition, the SureSight and the Retinomax Plus sphere and cylinder results showed moderate agreement with each other. Although the mean differences of the spherical equivalents determined were minimal, the 95% confidence intervals were large, which limits the value of the data obtained from each instrument. CONCLUSIONS: Even though the Retinomax Plus and the SureSight appear to agree with each other and with the results of cycloplegic retinoscopy for determining sphere and cylinder power, interpretation of the data should be considered as screening only because the actual magnitude of sphere and cylinder may vary from the actual magnitude. These results suggest that either device may be useful only as screening tools for assessing refractive error in pre-school children.

Child, Preschool↗
PubMed2004

Refractive error and visual impairment in urban children in southern china.

PURPOSE: To assess the prevalence of refractive error and visual impairment in school-age children in a metropolitan area of southern China. METHODS: Random selection of geographically defined clusters was used to identify children 5 to 15 years of age in Guangzhou. Children in 22 clusters were enumerated through a door-to-door survey and examined in 71 schools and 19 community facilities from October 2002 to January 2003. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy, and autorefraction under cycloplegia and examination of the external eye, anterior segment, media, and fundus. RESULTS: A total of 5053 children living in 4814 households were enumerated, and 4364 (86.4%) were examined. The prevalence of uncorrected, presenting, and best-corrected visual acuity 20/40 or worse in the better eye was 22.3%, 10.3%, and 0.62%, respectively. Refractive error was the cause in 94.9% of the 2335 eyes with reduced vision, amblyopia in 1.9%, other causes in 0.4%, and unexplained causes in the remaining 2.8%. External and anterior segment abnormalities were seen in 1496 (34.3%) children, mainly minor conjunctival abnormalities. Media and fundus abnormalities were observed in 32 (0.73%) children. Myopia (spherical equivalent of at least -0.50 D in either eye) measured with retinoscopy affected 73.1% of children 15 years of age, 78.4% with autorefraction. The prevalence of myopia was 3.3% in 5-year-olds with retinoscopy and 5.7% with autorefraction. Females had a significantly higher risk of myopia. Hyperopia (+2.00 D or more) measured with retinoscopy was present in 16.7% of 5-year-olds, 17.0% with autorefraction. The prevalence of hyperopia was below 1% in 15-year-olds, with both methods. Astigmatism (cylinder of > or = 0.75 D) was present in 33.6% of children with retinoscopy and in 42.7% with autorefraction. CONCLUSIONS: The prevalence of reduced vision because of myopia is high in school-age children living in metropolitan Guangzhou, representing an important public health problem. One third of these children do not have the necessary corrective spectacles. Effective strategies are needed to eliminate this easily treated cause of significant visual impairment.

Adolescent↗
PubMed2006

[Comparisons of manual and automatic refractometry with subjective results].

BACKGROUND: Refractometry is very important in everyday clinical practice. The aim of this study is to compare the precision of three objective methods of refractometry with subjective dioptometry (Phoropter). The objective methods with the smallest deviation to subjective refractometry results are evaluated. MATERIALS AND METHODS: The objective methods/instruments used were retinoscopy, Prism Refractometer PR 60 (Rodenstock) and Auto Refractometer RM-A 7000 (Topcon). The results of monocular dioptometry (sphere, cylinder and axis) of each objective method were compared to the results of the subjective method. The examination was carried out on 178 eyes, which were divided into 3 age-related groups: 6 - 12 years (103 eyes), 13 - 18 years (38 eyes) and older than 18 years (37 eyes). All measurements were made in cycloplegia. RESULTS: The smallest standard deviation of the measurement error was found for the Auto Refractometer RM-A 7000. Both the PR 60 and retinoscopy had a clearly higher standard deviation. Furthermore, the RM-A 7000 showed in three and retinoscopy in four of the nine comparisons a significant bias in the measurement error. CONCLUSIONS: The Auto Refractometer provides measurements with the smallest deviation compared to the subjective method. Here it has to be taken into account that the measurements for the sphere have an average deviation of + 0.2 dpt. In comparison to retinoscopy the examination of children with the RM-A 7000 is difficult. An advantage of the Auto Refractometer is the fast and easy handling, so that measurements can be performed by medical staff.

Adolescent↗
PubMed2005

Retinoscopy/autorefraction: which is the best starting point for a noncycloplegic refraction?

PURPOSE: The aim of this study was to estimate the agreement between an autorefractor (Nidek ARK 700A, Gamagori, Japan) and retinoscopy with subjective refraction. METHODS: Measurements of autorefraction obtained with the ARK700A and retinoscopy were performed on 192 right eyes from 192 healthy young adults and compared with subjective refraction. These measurements were performed without cycloplegia. The age range was 18 to 34 years, with a mean value of 21.6 years and an SD of 2.66 years. RESULTS: A comparison of the autorefractor and subjective refraction results shows that (1) for the mean spherical equivalent (M), the autorefractor yields more negative values (-0.44 +/- 0.54 D; p = 0.000); (2) for the Jackson cross-cylinder at axis 0 degrees (J0), the autorefractor yields more positive values than the subjective ones (0.05 +/- 0.13 D; p = 0.000); and (3) for the Jackson cross-cylinder at axis 45 degrees (J45), the autorefractor results are more negative (-0.02 +/- 0.09 D; p = 0.019). The differences found for each component M, J0, and J45 are statistically significant. By comparing retinoscopy with the subjective examination, there are no statistically significant differences found for the M component (-0.02 +/- 0.33 D; p = 0.304). For the J0 and J45 components, the differences are statistically significant (0.07 +/- 0.10 D, p = 0.000; -0.01 +/- 0.08 D, p = 0.008). CONCLUSIONS: The present results confirm that when performed by an experienced clinician, retinoscopy is more accurate than automatic refraction, giving a better starting point to noncycloplegic refraction.

Adult↗
PubMed2005

Refractive error and visual impairment in school-age children in Gombak District, Malaysia.

PURPOSE: To assess the prevalence of refractive error and visual impairment in school-age children in Gombak District, a suburban area near Kuala Lumpur city. DESIGN: Population-based, cross-sectional survey. PARTICIPANTS: Four thousand six hundred thirty-four children 7 to 15 years of age living in 3004 households. METHODS: Random selection of geographically defined clusters was used to identify the study sample. Children in 34 clusters were enumerated through a door-to-door survey and examined in 140 schools between March and July 2003. The examination included visual acuity measurements; ocular motility evaluation; retinoscopy and autorefraction under cycloplegia; and examination of the external eye, anterior segment, media, and fundus. MAIN OUTCOME MEASURES: Distance visual acuity and cycloplegic refraction. RESULTS: The examined population was 70.3% Malay, 16.5% Chinese, 8.9% Indian, and 4.3% of other ethnicity. The prevalence of uncorrected (unaided), presenting, and best-corrected visual impairment (visual acuity < or =20/40 in the better eye) was 17.1%, 10.1%, and 1.4%, respectively. More than half of those in need of corrective spectacles were without them. In eyes with reduced vision, refractive error was the cause in 87.0%, amblyopia in 2.0%, other causes in 0.6%, and unexplained causes in 10.4%, mainly suspected amblyopia. Myopia (spherical equivalent of at least -0.50 diopter [D] in either eye) measured with retinoscopy was present in 9.8% of children 7 years of age, increasing to 34.4% in 15-year-olds; and in 10.0% and 32.5%, respectively, with autorefraction. Myopia was associated with older age, female gender, higher parental education, and Chinese ethnicity. Hyperopia (> or =2.00 D) with retinoscopy varied from 3.8% in 7-year-olds, 5.0% with autorefraction, to less than 1% by age 15, with either measurement method. Hyperopia was associated with younger age and "other" ethnicity. Astigmatism (> or =0.75 D) was present in 15.7% of children with retinoscopy and in 21.3% with autorefraction. CONCLUSIONS: Visual impairment in school-age children in urban Gombak District is overwhelmingly caused by myopia, with a particularly high prevalence among children of Chinese ethnicity. Eye health education and screening may help address the unmet need for refractive correction.

Adolescent↗
PubMed1981

Cycloplegic refraction in esotropic children. Cyclopentolate versus atropine.

Retinoscopy was performed on a population of predominantly white esotropic children younger than 5.5 years with cyclopentolate 1% and atropine 1.0%. Atropine 1.0% revealed +0.34 diopters more hyperopia than cyclopentolate 1.0%, when the mean differences between the two drugs were examined. Mean difference analysis would probably indicate that atropine retinoscopy was unnecessary. However, 22% of the children had +1.0 diopters or more of hyperopia uncovered by atropine. This significant subpopulation suggests that in young patients with esotropia, an atropine refraction is essential to uncover the maximum amount of hyperopia. Almost all of this subgroup with +1.00 or greater hyperopia had an initial cyclopentolate retinoscopy of +2.00 diopters or more. Therefore, retinoscopy using atropine cycloplegia becomes even more important in this population. There was a trend for the greater differences to be in children older than age 2 years. However, these values were not statistically significant.

Accommodation, Ocular↗
PubMed2001

[Accuracy of measurements of video-refractometry in higher ametropia].

BACKGROUND: Measurement of refraction of non-cooperative patients is a real challenge for the ophthalmologist. Retinoscopy produces exact results in experienced hands, but requires practice and time. The Videorefractor VRB 200 (manufactured by Tomey, Erlangen) was especially designed for refracting children. The aim of this study is to prove the accuracy of this tool in measuring refraction. MATERIAL AND METHODS: 259 patients (age 10 month to 77 years) were measured with the VRB 200. Each patient was examined by retinoscopy in cycloplegia and refracted with the Topcon autorefraktor RM-A 6000. Ametropia was evoked at 5 emmetropic volunteers by lenses of different power, placed in a trial frame. These measurements were performed with and without use of cycloplegic drugs. RESULTS: The VRB 200 showed an average error of spherical equivalent at ametropia of the range -4 to +4 Diopters (dpt) < 2 dpt. At higher ametropia the error grew increasingly. Repeated measurements of one patient showed high variation of the results. Astigmatism was measured worse by growing magnitude, especially at diagonal axis (45 degrees and 135 degrees). Anisometropia > 2 dpt has been discovered in only 72%. It was possible to examine many infants and handicapped patients, which was impossible by using the RM-A 6000. An examination by retinoscopy was possible in all cases, but needed a lot of time and patience. CONCLUSIONS: The concept of good handling suffers especially by the increasing inaccuracy at ametropia beyond +/- 4 dpt. At this state of development the VRB 200 is no alternative in practical use to the conventional retinoscopy.

Adolescent↗
PubMed1994

[How accurate is video refraction measurement in infants in comparison with skiascopy? How much do the values change within a half a year?].

BACKGROUND: Isotropic photorefraction (Atkinson et al., 1981) is a method used to screen the refraction in infants. The aim of this study is to analyze its limitations as a measuring instrument. MATERIALS AND METHODS: 215 children aged between 5 and 12 months were examined in cycloplegia. The results were subsequently compared (1) to the results of streak retinoscopy also performed at the same time and (2) to photorefraction performed a second time, 6 months later (with 145 children). RESULTS: Spherical refraction: The mean spherical values differed by 0.70 dpt through photorefraction methods, compared to retinoscopy. The standard deviation (SD) was 0.67 dpt. The values of the photorefraction differed therefore in 95% of the children within a range of 2.7 dpt (or +/- 2 SD). Compared to the second photorefractive measurement 6 months later, the average refraction showed a small myopic shift (-0.45 dpt). Astigmatism: The errors of measurement were more pronounced here. Extreme differences of up to 9 dpt were found in single cases. The mean difference, compared to retinoscopy, was 0.73 dpt. The standard deviation (SD) was 0.90 dpt. In 95% of the children, the values of photo-refraction differed therefore by a range of 3.6 dpt (or +/- 2 SD). Compared to the second photorefractive measurement 6 months later, the average refraction showed a mean change of 0.73 dpt. CONCLUSIONS: Our photorefractive measurements showed errors in the range of 1-2 dpt for the spherical refraction, and in the range of 2-3 dpt for astigmatism. In 5% of the children examined, even greater aberrations were found. As long as the aim of photorefraction is restricted to disclosing high refractive errors, this method is judged suitable for the refractive screening of infants. For more precise refraction, and for the prescription of spectacles, we believe that is should be supplemented by a second examination technique, such as retinoscopy or automated refractometry.

Astigmatism↗
PubMed1998

How accurate is the hand-held refractor Retinomax(R) in measuring cycloplegic refraction: a further evaluation.

AIMS To assess the agreement between the hand-held autorefractor Retinomax(R) and three different on-table autorefractors when measuring cycloplegic refraction in subjects with small and high ametropia. To assess the agreement between the cycloplegic refraction using the Retinomax(R) and by retinoscopy in children with small and high ametropia. METHODS Part A.276 subjects were refracted under cycloplegia using both the Retinomax(R) and an on-table infrared automated refractor (Topcon RM-A 6000, Nidek AR 800 or Nikon NR 5000). They were separated into subjects withsmall ametropia (mean sphere </= 3.5 D hyperopia, </= 3 D myopia) and high ametropia (mean sphere > 3.5 D hyperopia, > 3 D myopia). The agreement between both types of refractors regarding the different refractive components was assessed for the whole group and for the two subgroups of small and high ametropia. Part B. 48 infants were refracted under cycloplegia by retinoscopy and by the Retinomax(R). The agreement between both methods of refraction was analyzed in the same manner as in part A. RESULTS Part A. No significant bias was found between the two types of refractors with regard to the spherical equivalent. The 95% limits of agreement were +/- 1 D. Although no clinically significant bias was found with regard to the cylinder power in the 276 subjects, it was found that the 95% limits of agreement were much better (+/- 0.75 D) in small ametropia subjects than in high ametropia subjects (-2.1 to +1.3 D). No significant bias was found with regard to the axis determination. Part B. No significant bias was found between the Retinomax(R) and retinoscopic measurements with regard to the spherical equivalent. The 95% limits of agreement were -1.36 to +1.76 D. However, the mean difference for spheres and cylinders showed a positive bias and a negative bias, respectively, suggesting more positive spheres and larger cylinders when measured by the Retinomax(R) compared to retinoscopy. This was particularly obvious in cases of high ametropia. CONCLUSION Compared to retinoscopy and on-table autorefraction, the hand-held refractor Retinomax(R) is accurate in any ametropia with respect to the spherical equivalent. In small ametropia, there is a good accuracy when measuring the three refractive components (sphere, cylinder and axis). The accuracy decreases in high ametropia, especially with regard to the cylinder power.

Journal Article↗
PubMed1993

Comparing the amplitude of accommodation determined objectively and subjectively.

The purpose of this study was to determine if differences exist between subjective and objective methods of measuring the amplitude of accommodation. In a double-masked study on 57 patients, ages 6 to 35 years, 2 examiners measured the amplitude, 1 using the subjective push-up method and the other using a modified form of dynamic retinoscopy. Significant differences among the findings occurred (p < 0.001), the amplitude of accommodation being on the average 2.7 D higher with dynamic retinoscopy. The amplitudes as determined subjectively for each eye were highly correlated (gamma = 0.92), as were the objective findings (gamma = 0.85). Four other examiners also used this method of dynamic retinoscopy to determine the amplitude of accommodation on 43 patients, ages 11 to 39 years. For three examiners, the average amplitude of accommodation measured objectively was statistically similar to that measured subjectively. For the other examiner, the objective findings were on the average 1.19 D higher than the subjective findings. This study suggests that this modified form of dynamic retinoscopy can give consistent results, although different for some examiners than the traditional push-up method when determining the amplitude of accommodation.

Accommodation, Ocular↗
PubMed2006

Development of astigmatism and anisometropia in preterm children during the first 10 years of life: a population-based study.

OBJECTIVE: To assess the development of astigmatism and anisometropia to 10 years of age in preterm children, previously included in a population-based study on the incidence of retinopathy of prematurity. METHODS: Cycloplegic retinoscopies were performed in 198 preterm children at 6 months, 2(1/2) years, and 10 years of age. We analyzed the development of astigmatism of 1 diopter (D) or more and anisometropia of 1 D or more. RESULTS: The amount and prevalence of astigmatism declined between 6 months and 2(1/2) years of age and then remained stable. We found no difference in the course of astigmatism at different ages with regard to stage of retinopathy of prematurity. The amount of anisometropia increased, but its prevalence remained unchanged. Multiple regression analyses showed that astigmatism of 1 D or more at 2(1/2) years of age and cryotreated severe retinopathy of prematurity were risk factors for astigmatism at 10 years of age, and that anisometropia of 2 D or more at 2(1/2) years of age was a risk factor for anisometropia at 10 years of age. CONCLUSIONS: The development of astigmatism and anisometropia showed a similar course, regardless of stage of retinopathy of prematurity. The retinoscopy findings at 6 months of age were of no value in predicting astigmatism and anisometropia at 10 years of age, but the refraction at 2(1/2) years of age was. Retinoscopy at about 2(1/2) years of age in all preterm children may be useful for detecting astigmatism and anisometropia that will persist in children of school age.

Anisometropia↗
PubMed2004

Clinical comparison of the Welch Allyn SureSight handheld autorefractor versus cycloplegic autorefraction and retinoscopic refraction.

PURPOSE: To investigate the accuracy of the Welch Allyn SureSight (WASS; Welch Allyn, Skaneateles Falls, New York) hand-held autorefractor in noncyclopleged children and to compare the results with those obtained in cyclopleged children using the Nidek AR-820 (NAR; Nidek, Aichi, Japan) and retinoscopic refraction (RR) of an experienced pediatric ophthalmologist. METHODS: Ninety-one children (mean age 97 months +/- 19, range 37 to 107) whose vision screening, performed by a school nurse and/or by their primary care provider, was unsuccessful were prospectively evaluated in the private practice of a university pediatric ophthalmologist. After completion of a history, each child was refracted using the WASS. A complete ophthalmic examination, including cycloplegic refraction using the NAR and retinoscopic refraction refined to obtain a visual acuity of at least 20/30 diopters, was then performed. The physician was masked to the previous WASS and NAR results. Analysis variables included race, age (months), refraction (sphere, cylinder, axis), and initial and final corrected visual acuity. Only WASS values for which reliability was > or = 8 were used. A coin toss determined which eye would be used for analysis. RESULTS: Using analysis of variance and Scheffé multiple comparison testing, sphere results obtained by the WASS indicated a statistical difference compared with those obtained using the NAR (P =.0027) and retinoscopy (P =.0088). Similarly, spherical equivalence results obtained by the WASS also indicated a statistical difference compared with that of the NAR (P =.0027) and retinoscopy (P =.0056). Myopic sphere and spherical equivalent values were recorded more frequently with the WASS than with the NAR or refined retinoscopy. Cylindrical values comparing the WASS with the NAR, the WASS with RR, and the NAR with RR were statistically similar to each other (P =.9993,.748, and.7261 respectively). Axial results for patients with +0.50 or more of astigmatism were also statistically similar by all 3 methods. CONCLUSIONS: Our data indicate that when the WASS is used on noncyclopleged children as suggested for primary care providers, myopia may be overdiagnosed.

Analysis of Variance↗