The classification of amblyopia on the basis of visual and oculomotor performance.
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Adolescent↗
Biomedical subjects
C Hsu-Winges
Publications and source records attributed to C Hsu-Winges.
The development of monocular and binocular VEP acuity.
The development of monocular and binocular grating acuity was measured in 87 infants, 2-52 weeks of age, using the sweep VEP technique. Average monocular and binocular acuity growth functions were nearly identical, with a small (less than 0.2 octaves) binocular acuity superiority occurring only under 6 months. Interocular acuity differences were small (averaging less than 1/4 octave, unsigned, with a 95% confidence interval of less than +/- 0.6 octaves) and were not significant at any age. These characteristics make the sweep VEP technique a potentially sensitive tool for the detection of monocular visual losses in the early stages of amblyopia.
Child Development↗
Arden contrast sensitivity testing in glaucoma.
Two hundred sixteen eyes (164 patients) were studied with the Arden printed contrast gratings to test Arden's hypothesis that an abnormal score would distinguish between eyes with and without glaucoma. Ninety-five eyes were normal and 75 eyes were glaucomatous; 46 eyes suspected of being glaucomatous were also studied to determine whether such eyes would score differently than eyes with normal intraocular pressures. No age-dependent trend in scoring was found in the different diagnostic categories, except with the age group younger than 40 years, which had consistently better contrast sensitivity. The tests were demonstrated to be reproducible over time and showed little or no intertester variability. Decreased contrast sensitivity was found in the glaucomatous eyes compared with normal eyes. The scores of the eyes suspected of being glaucomatous fell between the scores of the glaucomatous and normal eyes. Overlapping distributions among the three groups, however, limit the diagnostic value of the test.
Adult↗
Polaroid photorefractive screening of infants.
We modified a Polaroid SE camera for use as a photoretinoscope. A total of 187 infants between 2 and 18 months of age were photographed using this device. About half of these infants (97) participated in a double blind study in which the results of photorefraction were compared with those of standard cycloplegic retinoscopy. Eighty-three infants were photographed without cycloplegia. Thirty-four infants were photographed while cyclopleged. Photographs were evaluated for significant refractive errors and other ocular abnormalities. The effectiveness of the camera system to screen for significant refractive errors without the use of cycloplegia was assessed. Infants were identified to be at risk by photorefraction if, in any photograph, a hyperopic bright crescent calculated to be greater than or equal to +1.25 D was present in the pupil. Clinically significant refractive errors were defined by the results of cycloplegic retinoscopy: "at-risk" infants had either 3.5 D or more hyperopia in either eye, or astigmatism in either eye greater than or equal to 2.5 D, or anisometropia greater than or equal to 1.5 D. With these clinical criteria and the above photographic screening criterion, the camera's sensitivity and specificity were 83% and 69%, respectively. The present system compares favorably with earlier, more sophisticated units in alerting practitioners to potentially significant refractive errors in infants. Additionally, as a screening tool, this device offers the benefits of being inexpensive and easy to use, and of providing immediate feedback.
Calibration↗
Comparison of on- and off-axis photorefraction with cycloplegic retinoscopy in infants.
We have compared the performance of an off-axis (knife-edge) photorefractor with that of an on-axis (isotropic) system. Normal infants and children between the ages of 8 and 208 weeks were photographed with each camera both with and without cycloplegia. Refractive errors were estimated for each technique based on equations derived from ray-tracing. These refractions were compared to the results of retinoscopy under cycloplegia. Sensitivity and specificity of the two photorefraction systems were evaluated as a function of the magnitude of meridional hyperopia defined by retinoscopy. We also examined the effect of varying the photorefraction screening criterion. Thirteen percent of the infants in the screening sample presented with +3.50 diopters or more of meridional hyperopia. Using this level of ametropia as a referral criterion, the sensitivity and specificity of the off-axis system for infants without cycloplegia were 83% and 72%, respectively. For the on-axis system, sensitivity and specificity values were 85% and 53%. The use of cycloplegics did not significantly improve the performance of either system, but rather their use degraded the specificity of the on-axis system in the presence of moderate refractive errors. The results of the present study indicate that both on- and off-axis systems are effective in identifying highly ametropic infants, but that the off-axis system results in significantly fewer false positives. Moreover, the off-axis system has the advantages of an inherently greater dynamic range for a fixed camera design, and also more easily interpreted photographs.
Child, Preschool↗