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1.
AIMS: To assess the reliability of the hand held automated refractor Retinomax in measuring astigmatism in non-cycloplegic conditions. To assess the accuracy of Retinomax in diagnosing abnormal astigmatism in non-cycloplegic refractive screening of children between 9 and 36 months. METHODS: Among 1205 children undergoing a non-cycloplegic refractive screening with Retinomax, 299 (25%) had repeated non-cycloplegic measurements, 302 (25%) were refracted under cycloplegia using the same refractor, and 88 (7%) using retinoscopy or an automated on table refractor. The reproducibility of non-cycloplegic cylinder measurement was assessed by comparing the cylindrical power and axis values in the 299 repeated measurements without cycloplegia. The influence of the quick mode on cylinder measurement was analysed by comparing the cylinder and axis value in 93 repeated measurements without cycloplegia where normal mode was used in one measurement and quick mode in the other. Predictive values of the refractive screening were calculated for three different thresholds of manifest astigmatism (> or = 1.5, > or = 1.75, and > or = 2 D) considering as a true positive case an astigmatism > or = 2 D under cycloplegic condition (measured by retinoscopy, on table, or hand held refractor). RESULTS: The 95% limits of agreement between two repeated manifest cylinder measurements with Retinomax attained levels slightly less than plus or minus 1 D. The 95% limits of agreement for the axis were plus or minus 46 degrees. The comparison of non-cycloplegic measurements in the quick and normal mode showed no significant difference and 95% limits of agreement plus or minus 0.75 D. The mean difference between non-cycloplegic and cycloplegic cylinder values measured by Retinomax reached 0.17 D and was statistically significant. Manifest thresholds of > or = 1.5 D, > or = 1.75 D, > or = 2 D cylinder value diagnosed 2 D of astigmatism under cyclplegia respectively with 71-84%, 59-80%, 51-54% of sensitivity (right eye-left eye) and 90-92%, 95%, 98% of specificity. CONCLUSION: Without cycloplegia, Retinomax is able to measure cylinder power with the same reproducibility as cycloplegic retinoscopy. No significant difference was found in the cylinder values obtained with the quick and the normal modes. Therefore, the quick mode of measurement is recommended as it is more feasible in children. No difference, which is significant from a screening point of view, exists between the non-cycloplegic and the cycloplegic cylinder value (< 0.25 D). Retinomax diagnoses abnormal astigmatism (> or = 2 D) in a non-cycloplegic refractive screening at preschool ages with 51-84% sensitivity rates and 98-90% specificity rates, depending on the chosen threshold of manifest astigmatism. If 2 D of manifest astigmatism is chosen as a positive test, the positive predictive value of the screening reaches 81-84% and the negative predictive value 91-90% (right eye-left eye).  相似文献   

2.
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 retino scopy, 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.

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4.
BACKGROUND—Overcorrection following myopic photorefractive keratectomy, with a target of emmetropia, leaving a spherical equivalent of more than 1.0 D of hyperopia is of the order of 1%. This study analyses the efficacy, safety, and 1 year stability of outcome of laser thermokeratoplasty (LTK) carried out on eyes with persistent symptomatic hyperopia following photorefractive keratectomy (PRK) for myopia.
METHOD—11 consecutive eyes in 11 patients underwent LTK using the Technomed Holmium 25, contact holmium:YAG laser system. The mean spherical equivalent before LTK was +2.06 D (SD 1.02 D, range +1.00 D to +4.75 D) based on a non-cycloplegic refraction. Between four and 16 burns were used per eye, depending on the error to be corrected.
RESULTS—The mean spherical equivalent was +0.511 D (SD 0.551) at 1 year. Ten of the 11 eyes were seeing 6/12 or greater, unaided (91%) and nine were within 1.0 D of the target sphere equivalent (82%). Recovery of unaided acuity occurred during the first week in four cases and the first month in the rest. One eye lost greater than one line of best corrected vision (9%), going from 6/5 to 6/7.5 and one gained a line (9%), 6/12 to 6/7.5. No complications occurred during the follow up period.
CONCLUSIONS—In this study of a small number of eyes with hyperopia induced by PRK, LTK appears safe, predictable, and stable for low errors followed for 1 year.

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5.
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). 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.  相似文献   

6.
AIMS: To assess non-cycloplegic screening for amblyopia with the hand held Nikon Retinomax autorefractor in 3 year old kindergarten children. METHODS: 427 three year old children were examined in kindergarten with the Retinomax without cycloplegia. A gold standard was established in all children by two orthoptic examinations in kindergarten. If there were missing, abnormal, or inconsistent findings, children were referred for ophthalmological examination. If, by the ophthalmological examination, a new case of amblyopia requiring treatment was diagnosed, the gold standard was set "positive." RESULTS: In 404 children the gold standard was obtained. 10 children (2.5%) had a "positive" gold standard of unknown and untreated amblyopia. Screening sensitivity was 0.80, specificity 0.58, accuracy 0.58, and the likelihood ratio 1.89. CONCLUSION: Non-cycloplegic refractive screening with the Retinomax led to many false positive referrals due to instrument myopia and "inconclusive" results. Hence specificity, accuracy, and the likelihood ratio were too low to conduct screening effectively.  相似文献   

7.
BACKGROUND—Infants who require treatment for threshold retinopathy of prematurity are at increased risk of developing refractive errors. Following the introduction of laser treatment for threshold disease, the clinical impression was that the degree of myopia was reduced compared with cryotherapy.
METHODS—A longitudinal study was carried out of refractive error at 3 and 12 months in 19 patients undergoing cryotherapy and 15 patients undergoing laser treatment.
RESULTS—At 3 months the median spherical equivalent refractive error in the right eye was −3.25 dioptres after cryotherapy and +0.25 dioptres after laser therapy (similar results left eye). The median spherical equivalent refractive error in the right eye at 12 months was -5.25 dioptres following cryotherapy and -0.50 dioptres after laser (similar results left eye). There was a statistically significant difference in median spherical refractive error between the therapies at 3 months and 12 months (p<0.05 Wilcoxon rank sum) in both eyes.
CONCLUSION—Laser therapy is associated with lower degrees of myopia during the first year of life, which is clinically significant in terms of visual performance and development.

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8.
PurposeTo evaluate the performance of the hand-held and table-top autorefractokeratometer in measuring refractive errors by comparing them with cycloplegic retinoscopy.MethodsIncluded 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.ResultsThe 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.ConclusionsThe refractive error components were highly correlated between the two instruments and cycloplegic retinoscopy.  相似文献   

9.
AIM—Some surgeons consider hand held surgical keratometers unreliable. This may be due to incorrect use through not realising that the distance that the keratometer is held from the cornea influences the shape of the image. When a keratometer is held closer to the astigmatic cornea, the elliptical image will appear more circular, particularly for larger degrees of astigmatism. However, the keratoscopic astigmatic ruler (KAR) has design features that correct the hitherto unrecognised problems with the use of a hand held keratometer. This study assesses the reliability and accuracy of measurement of astigmatism using the KAR.
METHODS—The KAR and the Bausch & Lomb keratometer (B&L) were compared using six back surface toric cut contact lens blanks representing 1 to 6 dioptres of astigmatism. Two observers (one experienced in the use of the keratometers, the other a novice) took eight randomly repeated "masked" measurements of each lens blank with the KAR and four measurements with the B&L in a similar fashion.
RESULTS—There was no difference between the measurements with either instrument by each of the observers (p=0.95, ANOVA). The standard error of measurement for the KAR was 0.59 D, for the B&L, 0.31 D. The intraclass correlation coefficient of reliability for the KAR was 0.90 and for the B&L it was 0.97. The coefficient of repeatability for the KAR was plus or minus 0.83 D, and for the B&L plus or minus 0.77 D. The interobserver reliability for the KAR was 0.898, and for the B&L, 0.975.
CONCLUSION—These results suggest that the KAR has good reliability and reproducibility and compares favourably with the B&L keratometer. Inexperience with use does not affect reliability.

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10.
PURPOSE: To compare the results of manifest refraction obtained with two different hand-held autorefractors (Sure-Sight, Welch Allyn Co. and Retinomax 1, Nikon Inc.) and with the Topcon RMA 6000 on-table autorefractor in order to estimate any potential bias between these refractometers and to compare the diagnostic performances of these two hand-held autorefractors as screening devices. METHODS: Ninety-eight children were refracted under manifest conditions with the three above-mentioned refractometers and under cycloplegic conditions with the Topcon on-table autorefractor, or by means of retinoscopy. The agreement between the manifest measurements obtained with the three different autorefractors was studied using the method of Bland and Altman. The validity of several thresholds of manifest refractive anomalies as measured with the Sure-Sight and with the Retinomax was estimated by receiver operating characteristic (ROC) curves using cycloplegic measures as reference. results There is a spherical positive bias of 1 D between the Sure-Sight and the Retinomax and better agreement between the Topcon and the Retinomax. The surface area indexes of the ROC curves and the diagnostic performances in term of sensitivity and specificity are better with the Retinomax in cases of hyperopia, astigmatism and anisometropia. For myopia, the Sure-Sight has better performance. CONCLUSIONS: The results suggest that either device may be sufficient for assessing refractive errors in children in a screening setting. However, because of a bias between both refractometers in measuring the sphere, distinctive referral criteria must be chosen for the detection of hyperopia and myopia. The diagnostic performance is slightly in favor of the Retinomax.  相似文献   

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