Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038379 (strabismus)
 9,317 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rhesus monkey has evolved as a useful model for the study of amblyopia caused by neonatal lid closure and experimental strabismus and anisometropia. In view of the behavioral and anatomic similarities of the visual system in humans and rhesus monkeys, there is reason to believe that the neurophysiologic and anatomic anomalies identified in animals as part of the "visual deprivation syndrome" occur in humans as well. Animal research has led to better understanding of the basic mechanisms responsible for the development of amblyopia and the manner in which form vision deprivation and abnormal binocular interaction contribute to the various forms of unilateral and bilateral amblyopia. The period of susceptibility to abnormal visual stimulation in humans needs to be better defined, and the clinician must take precautions to avoid uncontrolled occlusion or prolonged unilateral cycloplegia in infants. Even though the factors leading to amblyopia in patients with unilateral or bilateral congenital cataracts are now better understood, the visual results are still disappointing. It is possible that the residual aniseikonia after contact lens correction may be amblyopiogenic in these patients.
 ...
PMID:Application of basic research data to clinical amblyopia. 9 8

215 preschool siblings of children presenting with squint/amblyopia were screened by refraction after cycloplegia. The presence of +2.00 or more D of spherical hypermetropia in both eyes, or +1.00 or more D sphere or cylinder of anisometropia was significantly associated (P=0.0779%) with that child being identified 2+ years later as having either squint or amblyopia or both. Astigmatism of +1.50 or more D in either eye was significantly associated with anisometropia (P=0.000 0013%). If bilateral hypermetropia of +2.00 or more DS and/or +1.50 or more D of astigmatism in either eye had been taken as criteria for abnormality (ignoring anisometropia), there was a more significant association (P=0.0025%) between refraction and squint/amblyopia in these siblings. Such a child had 4 times more chance of having a visual defect than one who had no error of refraction when screened. These findings suggest that an environmental factor such as blurred vision may be relatively more important as a cause of squint/amblyopia than a genetically determined neurological abnormality.
 ...
PMID:Refraction as a means of predicting squint or amblyopia in preschool siblings of children known to have these defects. 43 40

Heterophoria, its influence on stereopsis, and the importance of cycloplegia in refraction testing of pilot applicants were studied. Distant heterophoria was found in 94.5-100% while near heterophoria was found in 86.9-98.1% of the cases, depending on the test used. Hyperphoria of over 1 prism diopter was extremely rare. No statistically significant correlation between distant heterophoria and the degree of stereopsis could be demonstrated at a range of up to at least 6 prism diopters. Cycloplegia induced a mean difference of +0.75 diopter in refraction before and during cycloplegia. Eight percent of the applicants failed because of refractive errors (spherical extremes, -0.75 diopter and +4.50 diopters; cylindrical extreme, 1.25 diopters). It is concluded that stereopsis does not seem to be affected much by heterophoria within moderate limits, and that cycloplegia in refraction testing of young pilot applicants must be considered relatively important.
 ...
PMID:Heterophoria--its influence on stereopsis and the importance of cycloplegia in refraction testing of pilot applicants. 65

The cycloplegic effect of 1% Atropine Sulphate, 2% Homatropine Hydrobromide and 1% Cyclopentholate (Cyclolat) were compared on 8 to 10 year-old children with hyperopic accommodation and partial accommodation squint. The objective refraction was measured by skiascopy and with Hartinger's refractometer, and these two values were compared. The distant-vision correction, and also the near-vision correction needed so that Table 2 of Pursch's Tables could be read, were measured. Atropine showed itself to be the most effective cycloplegic agent. With atropine cycloplegia was attained in 46.77% - shown by a necessary near-correction of +2 dioptres, or less. In 27.42% the correction was +1.5 dioptres. With homatropine a correction of +2 dioptres or less occurred in 82.14%, after Cyclogyl in 72.34%. Better cycloplegia could be reached, if before the test correcting spectacles are worn. Only with repeated refraction-tests to overcome accommodation spasm could one succeed in finding the complete hypermetropic state -- even with the help of a not very demanding cycloplegic agent like atropine. Cyclogyl was found to be the most suitable agent here.
 ...
PMID:[Cycloplegia and residual accommodation (author's transl)]. 124 85

Atropine is accepted generally as the most efficient cycloplegic agent. Although it is considered a relatively safe drug, toxic local and systemic side effects do occur. The recommended regimen for atropine cycloplegia has been 7 to 10 applications within 3 to 4 days. We compared the cycloplegic effect of four instillations of atropine drops to the effect of eight instillations. The results showed that the cycloplegia obtained after eight instillations was not greater than after four instillations.
J Pediatr Ophthalmol Strabismus
PMID:Atropine cycloplegia: how many instillations does one need? 143 3

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.
J Pediatr Ophthalmol Strabismus
PMID:Comparison of on- and off-axis photorefraction with cycloplegic retinoscopy in infants. 151 65

A new method for refractive measurements with atropine cycloplegia was tested in 90 children with squint. Measurements were taken by an autorefractor (Canon R 10) 90 min after application of 2 atropine eye drops and after 3 days of receiving 1 atropine eye drop 3 times daily, i.e. 9 drops per eye. Results were also compared to conventional "objective" refractometry by means of a hand refractometer (Rodenstock PR 50). According to this method, the total refraction, spherical and cylindric power and the cylinder axis are in agreement with refractive data in 80-90% of the children after 3-day atropinization. The additional cycloplegic effect of atropine given for 3 days is only 0.5 dptr compared to the application of 2 drops on the first day. So for practical purposes the refractive data evaluated after 90-min atropinization can be used as a basis for the prescription of glasses.
 ...
PMID:[Refraction by atrophine cycloplegia]. 201 28

We tested whether near retinoscopy, a noncycloplegic retinoscopic technique, was applicable to the optic correction of patients with accommodative esodeviations. We performed a study in 17 patients with accommodative esotropia to compare the refractive values obtained by near retinoscopy and by cycloplegia, as measured by two examiners. The interobserver variability was the same for the two techniques for the refractive values of the horizontal and vertical meridia and spherical equivalent. For the astigmatism, there was greater variability for near retinoscopy. The correlation between the two methods was good, but the variability of the differences was high. We recommend that near retinoscopy should be employed only as a noninvasive method for screening refractive errors in children.
J Pediatr Ophthalmol Strabismus
PMID:Near retinoscopy in accommodative esotropia. 224 37

Early screening for refractive errors is highly desirable. Techniques for doing this must be usable with noninstructable subjects (infants), noninvasive, and relatively easy to use. Photorefraction has been used to examine infants' refractive status. However, unless cycloplegia is used, the results can be difficult to evaluate, inasmuch as the subject's plane of focus is not known. This paper describes a photorefraction system that is being used for routine screening of young infants, without cycloplegia and without using highly skilled personnel. The major innovation is the systematic presentation of attractive targets at distances that present a range of demands to accommodation. Changes in the fundal reflections, seen in the photographs taken as the infant views the different targets, can be interpreted unequivocally to identify severe myopia and hyperopia, anisometropia, heterotropia, and anisocoria. The results can also be quantified and are compared with retinoscopic refractions.
 ...
PMID:Screening infant vision with paraxial photorefraction. 240 3

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.
J Pediatr Ophthalmol Strabismus
PMID:Polaroid photorefractive screening of infants. 279 16


1 2 3 4 Next >>