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A brief review of the pharmacological action of cycloplegic drugs is followed by a specification of the doses and actions of five commonly used cycloplegics. Some criterion for selecting a cycloplegic are presented.
The Ophthalmetron was used to measure the refractive error of 10 male optometry students. Although there was a high incidence of invalid readings, more repeatable results were obtained with use of a cycloplegic. Measurements made under cycloplegia revealed 0.41 D more hyperopia but no differences in astigmatism as compared to the noncycloplegic refraction. Instrument myopia was shown not to be a factor.
A drug registry was established at Southern California College of Optometry (SCCO) to study use rates and incidence of adverse side effects of the nine pharmaceutical agents in the California optometry law. Data were gathered in clinics of SCCO for 6 months and offices of 20 private practitioners for 3 months. Data included drugs used, the strength and dosage, patient age, sex, and racial or ethnic origin. Adverse drug reactions were reported in detail, including objective and subjective findings, duration of the reaction, and case disposition. A total of 12,493 drug applications were reported. A low incidence of adverse reactions, eight cases (0.208%), which produced no permanent effects, is sound evidence regarding the risk/benefit ratio in support of the use of pharmaceutical agents by optometrists.
This study represents the first national survey of optometrists in Canada. A mailed questionnaire was designed and implemented in order to discover how optometrists have reacted to the introduction of diagnostic pharmaceutical agent (DPA) legislation in Canada and to determine what variables are important predictors of DPA use. The data collected were also used to test the null hypothesis that DPA legislation does not affect the use of mydriatic/cycloplegic agents by optometrists. A stratified random sampling procedure was used to select 230 optometrists (roughly 10% of the practicing profession) for inclusion in the study. Over 90% of the subjects completed and returned the questionnaire. A statistically significant and important association was found between mydriatic/cycloplegic drug use and legislation (p less than 0.05 and odds ratio = 2.18). Legislation, type of practice, age, and optometry school attended were all found to be associated with DPA use.
This study was designed to provide information regarding two aspects of contrast sensitivity testing of aviator candidates: first to determine whether contrast sensitivity functions (CSF's) obtained with the Vistech Visual Contrast Test System (VCTS) are affected by cycloplegia and second to determine whether the VCTS provides useful CSF's under clinical screening conditions in a timely and simple manner. Contrast sensitivity thresholds were obtained at 5 spatial frequencies from 106 aviator candidates before and after administering a cycloplegic. CSF's obtained under cycloplegia were reduced by about 20%. The VCTS provided useful CSF's under military screening conditions, and added about 6 min to the time required for the standard flight physical.
A previous study has shown that stereothreshold varies as a function of the luminance difference between a target and its background. On the average, the stereothreshold at the isoluminance point is three times higher than when there is maximum luminance difference between the target and the background. One of the possible reasons for this finding is the effect of less than optimum accommodative response for isoluminant targets. This possibility has been investigated in this study. The results show that the suboptimal accommodative response cannot explain the high stereothreshold at isoluminance.
We investigated the validity of replacing cycloplegic retinoscopy with a noncycloplegic, "near" retinoscopy technique. We refracted a group of 31 infants (less than 2 years) and 43 children (greater than 2 years) with both techniques, grading our level of confidence in the result. Near retinoscopy gave on average a less hypermetropic result than cycloplegic retinoscopy by 0.39 D. The difference was significant in infants and for low levels of examiner confidence. However, a repeatability study showed that much of the variability in the infant group could be attributed to the poor repeatability of either retinoscopy technique. Agreement between the two techniques is improved by changing the suggested adjustment factor from 1.25 to 1.00 D for children and to 0.75 D for infants.
We measured distance refractive error (Dist R), dark refractive error (Dark R), and cycloplegic refractive error (Cyclo R) in 196 subjects whose ages ranged from 4 to 17 years, using the Canon Autoref R-1. We defined the values of (Dark R--Dist R) as DFcus (Dist R) and those of (Dark R--Cyclo R) as DFcus (Cyclo R) in this study. Although DFcus (Dist R) was larger in less myopic and more hyperopic eyes similar to DFcus (Cyclo R), it was zero or plus in high hyperopic eyes, unlike DFcus (Cyclo R). We found Dist R was more strongly influenced by Cyclo R than was Dark R. It is not adequate to use Dist R as the far point for precise evaluation of the dark focus. We should use the difference between Dark R vs. Cyclo R as the true value of the dark focus of accommodation.
Using simulated presbyopia we measured the effects of target vergence and pupil size on letter contrast sensitivity while subjects wore accurately centered simultaneous vision bifocal contact lenses. These experiments examined the increase in depth of focus provided by two bifocal contact lenses, and the effects of pupil size on near and distance vision. Monocular contrast sensitivity was assessed with three different designs of soft contact lenses. First, as a single vision control, we measured contrast sensitivity with a Bausch & Lomb, Optima 38 lens corrected for distance. We then measured contrast sensitivity with an Allergan Optical, Hydron Echelon, which is a diffractive simultaneous bifocal and a CIBA Vision, Spectrum, which is a concentric design, center-near, two-zone simultaneous vision bifocal. In general both bifocal contact lenses improved contrast sensitivity at near but decreased contrast sensitivity at distance (when compared to the single vision lens). With a fixed 3.5-mm artificial pupil, the Echelon lens had two clear peaks of sensitivity, one at distance (0.00 D) and one at near (-2.00 D), but the Spectrum lens had no clear peaks. Performance of the Spectrum lens depended on its center zone size. Near (-2.00 D) and distance (0.00 D) contrast sensitivity was measured with pupil sizes that ranged from 1 to 6 mm. The results showed that visual performance with a diffractive lens was almost independent of pupil diameter up to 3 to 4 mm but, as predicted, performance with the two-zone lens depended critically on pupil size.
PURPOSE: To examine (1) reproducibility of cycloplegic retinoscopy (C-RNS), cycloplegic autorefraction (C-Autoref), and noncycloplegic autorefraction (NC-Autoref), and (2) validity of C-Autoref and NC-Autoref compared with C-RNS in preschoolers with astigmatism. METHODS: Subjects were 36 Native American preschoolers. Three measurements of right eye refractive error were obtained with each of three methods: C-RNS (by three different retinoscopists), C-Autoref, and NC-Autoref (Nikon Retinomax K+). Vector methods (vector dioptric distance, VDD) were used in the analyses. RESULTS: Mean reproducibility was 0.41 D (SD = 0.18) for C-RNS, 0.25 D (SD = 0.17) for C-Autoref, and 0.37 D (SD = 0.21) for NC-Autoref. Mean agreement between C-Autoref and C-RNS ranged from 0.51 to 0.61 VDD (SD = 0.24 to 0.35), and ranged from 1.66 to 1.74 VDD (SD = 1.11 to 1.25) for agreement between NC-Autoref and C-RNS. Mean bias was -0.07 +0.21 x 149 and -1.33 +0.34 x 178 for C-Autoref and NC-Autoref, respectively. CONCLUSIONS: C-Autoref provided reliable and valid measurements of refractive error in young children. NC-Autoref measurements were reliable within subjects, but there was large variability in validity among subjects.
The indications, technique, and drugs for pupillary dilation in the pediatric emergency department have been discussed. Although mydriatic agents are relatively safe, they are not without risks. Physicians therefore need to familiarize themselves with possible adverse reactions that can result from their use. Even when using an appropriate agent, efforts must be made to limit systemic absorption.
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1 The mydriasis resulting from topical application of five atropine-like drugs was measured photographically in man. Drug potency was obtained from log dose-response curves. 2 The in vitro potency of eight cholinoceptor blocking drugs, including those studied in man, was obtained by measuring their affinity constants for binding to the receptors of an isolated preparation of the rabbit sphincter pupillae. Values agreed closely with those obtained for the muscarinic receptors of guinea-pig ileum. 3 In vitro and in vivo potency was compared to obtain a quantitative measure of the relative ease with which drugs gain access to the receptors after topical application. 4 The large differences that occur in the intensity and duration of the mydriatic response to atropine-like drugs is primarily the result of differences in their ability to blcok the receptors. Only with tropicamide does its relatively high accessibility affect its potency in man.
PURPOSE: To highlight an unusual organism causing a unilateral endophthalmitis by transplacental spread. METHOD: We report a case of Plesiomonas shigelloides endophthalmitis, presenting in a newborn, with co-existing septicaemia and meningitis. There was a significant maternal history of diarrhoea associated with the ingestion of oysters 2 weeks prior to delivery. RESULT: The endophthalmitis was treated with parenteral antibiotics and topical mydriatics with complete resolution, although subsequent assessment of the affected eye suggests a poor visual outcome. CONCLUSION: Endophthalmitis in the newborn is an unusual clinical finding and usually presents with other manifestations of bacteraemia. Plesiomonas shigelloides is fortunately an infrequent cause of neonatal infection, but is associated with a high degree of morbidity and mortality. We postulate that this neonate acquired P. shigelloides via the transplacental route, and suggest that this organism be included in the list of 'other' causes of transplacental infection that has been abbreviated to 'O' in the acronym 'TORCH'.
Isotropic photorefraction has been suggested as a suitable method for screening infants for refractive error. Recently published data suggested that reasonable consistency with retinoscopy results might be achieved using cycloplegic videophotorefraction (VPR) for spherical refractive error but that results might be unreliable for astigmatic errors. Non-cycloplegic VPR did not appear to produce results consistent with retinoscopy. A practical idea of how many children might be identified using this technique and how many missed was needed by personnel designing screening projects. Hence the VPR was tested by screening a population of 247 infants for significant refractive error, and comparing the results with cycloplegic retinoscopy. Sensitivity and specificity scores were calculated for a range of test levels of ametropia. Without cycloplegia, sensitivity of VPR was poor. With cycloplegia the situation was much improved, with sensitivity for hyperopia +4.00 D or over of 83.3% and specificity of 90.6%. Sensitivity for astigmatism of 1 D or greater (84.6%) was high but specificity was poor (45.6%). Acceptable sensitivity was achieved for identifying children in this age group at risk of developing squint and amblyopia due to refractive error, providing cycloplegia was used.
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Herpes zoster ophthalmicus (HZO) may occur spontaneously, but can be precipitated by stress, trauma, debility or systemic illness. A case is here reported of Herpes zoster involving the contralateral eye, associated with a midline skin rash, following cataract extraction under local anaesthesia.