摘要:

Background.The purpose of this study was to help determine the most appropriate target to be used for the assessment of the nearpoint of convergence, normative data for the break and recovery in adults, and the diagnostic value of the red-glass modification and repetition of the nearpoint of convergence.Methods.A total of 175 subjects with normal binocular vision and 38 subjects with convergence insufficiency were evaluated. The nearpoint of convergence was measured three ways, with an accommodative target, a penlight, and a penlight with red and green glasses. The nearpoint of convergence was also measured using a penlight for 10 repetitions.Results.Results suggest a clinical cutoff value of 5 cm for the nearpoint of convergence break and 7 cm for the nearpoint of convergence recovery with either an accommodative target or a penlight with red and green glasses.Conclusion.This study establishes normative data for the nearpoint of convergence break and recovery in the adult population and supports the value of various test modifications when other testing is equivocal.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.To describe the refractive error and ocular components of a large group of school-aged children as a function of age and gender.Methods.In this report, we describe the refractive error and ocular components of 2583 school-aged children (49.3% girls, overall mean [±SD] age 10.0 ± 2.3). Measurement methods included cycloplegic autorefraction, autokeratometry, videophakometry, and A-scan ultrasonography. For statistical comparisons across gender and age, a critical point of &agr; = 0.005 was used to assess significance because of the large sample size and the large number of comparisons made.Results.Of these 2583 children, 10.1% were myopic (−0.75 D or more myopia in both meridians), and 8.6% were hyperopic (+1.25 D or more hyperopia in both meridians). As would be expected, there was a significant effect of age on refractive error (spherical equivalent, p < 0.0001), toward less hyperopia/more myopia. There was no significant difference in the average refractive error between girls and boys (p = 0.0192). Girls had steeper corneas than boys (0.74 D steeper in the vertical meridian and 0.63 D steeper in the horizontal meridian, p < 0.0001). There were no significant differences in corneal power with age (p = 0.16). Both older age and male gender were significantly associated with deeper anterior chambers (p < 0.0001 for both). The crystalline lens showed significant thinning with age (p < 0.0001), however, there was no significant difference in the lens thickness between girls and boys (p = 0.66). Both Gullstrand lens power and calculated lens power showed significant effects of age and gender (p < 0.0001 for both). Girls, on average, had Gullstrand lens powers that were 0.28 D steeper and calculated lens powers that were 0.80 D more powerful than boys. Axial length also showed significant effects of age and gender (p < 0.0001 for both). Girls’ eyes were, on average, 0.32 mm shorter than those of boys.Conclusions.These cross-sectional data show a general pattern of ocular growth, no change in corneal power, and crystalline lens thinning and flattening between the ages of 6 and 14 years. Girls tended to have steeper corneas, stronger crystalline lenses, and shorter eyes compared with boys.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.The anterior chamber depth can be estimated by the slitlamp without additional attachments. The method involves increasing the length of a horizontal slit focused on the cornea until the corneal and iris/lens images appear to just touch. For a slitlamp angle of 60°, multiplying the just-touching slit length (JTSL) by 1.4 gives an estimate of the anterior chamber depth as measured by ultrasonography. The purpose of this study was to determine whether the slitlamp angle affects the accuracy of the procedure.Methods.The anterior chamber depth of 63 adult male and female subjects aged between 19 and 44 years was measured by A-scan ultrasonography and estimated by the slitlamp technique. The angle between the illumination and microscope systems was varied at 10° intervals from 30° to 70°.Results.The average ultrasonographic anterior chamber depth for all subjects was 3.23 ± 0.38 mm. The average JTSL was as follows: 30° = 1.5 mm, 40° = 1.7 mm, 50° = 2.1 mm, 60° = 2.3 mm, and 70° = 2.5 mm. The conversion ratio between the ultrasonographic anterior chamber depth and the average JTSL was as follows: 30° = 2.2, 40° = 1.9, 50° = 1.5, 60° = 1.4, and 70° = 1.3. The ultrasonic anterior chamber depth was best estimated at 60°. The 95% limits of agreement between the estimated and measured anterior chamber depth were as follows: 30° = −0.76 to +0.84 mm, 40° = −0.75 to +0.63 mm, 50° = −0.36 to +0.46 mm, 60° = −0.26 to +0.28 mm, and 70° = −0.45 to +0.41 mm.Conclusions.These results experimentally confirm Smith’s suggestion that the optimum slitlamp angle at which to accurately estimate the anterior chamber depth is 60°. At this angle, estimates of the anterior chamber depth are minimally deviated from the gold standard (A-scan ultrasonography). At a slitlamp angle of 60°, the JTSL can be converted to an estimate of the ultrasonic anterior chamber depth by multiplying it by 1.40.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

We assessed the repeatability and validity of the PowerRefractor and the Nidek AR-600A autorefractor. This is the first independent study conducted on adults to evaluate the performance of these instruments in a laboratory setting. Fifty subjects (23 males and 27 females) aged 16 to 61 years (mean, 37 ± 12) participated in the study. The validity of the PowerRefractor and the Nidek autorefractor readings were determined by comparing them to subjective refraction. Measurements of refractive error were obtained from the two instruments on two separate occasions to assess their repeatability. The measured refractive error was converted into a dioptric power matrix for data analysis. No significant difference was found between the measurements obtained with the two instruments and the subjective refraction. The estimate of refractive error given by the two instruments was also found to be repeatable. In addition to measuring the refractive error, the PowerRefractor also offers the facility to measure eye position, pupil size, and dynamics of accommodation. We suggest some improvements to the PowerRefractor measurement technique to standardize its clinical use and to improve accuracy.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.To develop a model eye to study laser-tissue interactions during retinal imaging with scanning ophthalmoscopy.Methods.A model eye was designed to match the optical properties of the human eye based on the Bennett and Rabbetts schematic eye.Results.Alterations in axial length resulted in changes in refractive error similar to those in the human eye (3.70 D for 1 mm in axial length). Perfusion-fixed retinal tissue could be successfully imaged using the Heidelberg Retina Tomograph and Optical Coherence Tomograph to provide images that are similar in quality to those obtainedin vivo.Conclusions.The model eye should be a valuable tool for investigating laser-tissue interactions during scanning laser ophthalmoscopy and the derivation of digital retinal and tomographic images. This model should also enable a determination of the accuracy with which digital imaging techniques, such as the optical coherence tomograph and Heidelberg Retina Tomograph, measure retinal structure.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.To develop a general setting–independent decision-analytical model that determines the costs, effectiveness, and cost-effectiveness of four screening strategies to detect amblyopia or amblyogenic factors in pre-school children and to apply the model in a German setting.Methods.The general setting–independent decision–analytical model was developed from the perspective of society and the statutory health insurance was developed. Outcomes were the total number of newly detected true positive cases of amblyopia and the costs per newly detected true positive case of amblyopia. Strategies were screening of high-risk children up to the age of 1 year (ophthalmologists), screening of all children up to the age of 1 year (ophthalmologists), screening of all children aged 3 to 4 years (pediatricians or general practitioners), and screening of children aged 3 to 4 years visiting kindergarten (orthoptists). For the application example in a German setting, data from the published medical literature were used.Results.In the base-case analysis of the application example, screening high-risk children by opthalmologists had the lowest average cost per case detected but became dominated (less effective and more costly than an alternative) if a low (5.3%) probability of familial clustering of strabismus was assumed. Considering the various assumptions tested in the sensitivity analysis, screening of all children up to the age of 1 year by opthalmologists was the only strategy not dominated by others. Detection rates, including cases detected before screening, were between 72% and 78% for the strategies that screen for all children.Conclusions.The model suggests that in Germany, both from a cost-effectiveness and a pure effectiveness point of view, screening all children up to the age of 1 year by opthalmologists is the preferred strategy to detect amblyopia or amblyogenic factors. All strategies left a significant portion of children undetected.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID