Jean-Cyriaque Barry

Objective Measurement of Small Angles of Strabismus in Infants and Children with Photographic Reflection Pattern Evaluation

A new photographic method for the precise measurement of the angle of squint in children and infants is presented. The apparatus consists of a reflex camera with three horizontally aligned flashes and a small fixation light. The subjects are photographed while fixating binocularly or monocularly in the primary or secondary position. Six reflections can be seen on the photograph of each pupil. These are the first and fourth Purkinje images of each light source. From the reflection patterns, the squint angle or the angle kappa or alpha can be computed using a simple formula. A vertical angle of strabismus may be calculated from the same photograph using the same principle. Results from orthotropic and strabismic adults and from children are evaluated to establish reference values. Cooperation from the children is generally very good. The accuracy of the new method is between between 2 and 4.5 prism diopters (between 1 degree and 2.5 degrees), depending on the measuring strategy.

The use of cycloplegic agents. Results of a 1999 survey of German-speaking centers for pediatric ophthalmology and strabology.

INTRODUCTION. Because of its advantages, topical cyclopentolate is often preferred over the gold standard, atropine. The purpose of this study was to obtain an overview over current cycloplegia protocols and to estimate the likelihood of severe complications due to the use of cycloplegics. METHODS. A questionnaire was sent to 107 German-speaking centers with a supposed high frequency of cycloplegias. RESULTS. 57 centers answered, whereby 1,112 cumulated years of experience with cycloplegia were available for analysis. The frequency of cycloplegias varied between 2 and 180/week/center, median 25/week/center. A cumulated total of 1.7 million cycloplegias was computed. The extrapolated average experience with cycloplegia was 49,000 cycloplegias/30 years. Complications which would warrant a medical follow-up of several hours (severe complications) or which led to a follow-up in a ward (very severe complications) were named 47 times and 2 times, respectively. DISCUSSION. During 30 years of a cycloplegia career with an average of 34 cycloplegias/week, one may expect 2-10 severe or very severe complications. In current practice, the patient risk of severe complications is very small. Health care professionals and parents should be informed about the frequent occurrence of harmless side effects in order to achieve a good compliance with cycloplegia.

A model for cost-effectiveness ratios in amblyopia screening

Background and purpose: In Germany, 750,000 children are born per year who should be screened for developmental visual defects in the age range 24–48 months. However, the established pediatric screening program is not sufficient to prevent amblyopia. The purpose of this study was to examine the cost-effectiveness of alternatives for amblyopia and microtropia screening. Methods: Three options were compared: (1) an orthoptic screening carried out in the field, for instance in kindergartens, (2) an examiner-independent objective apparatus-based screening, and (3) a complete ophthalmological and strabismological examination carried out in a practice. The costs of screening, follow-up examinations and of the treatment were modelled for prevalences of 1 % (microtropia) and 5 % (amblyopia). The benefit due to treatment was calculated as the result of an avoided whole-person impairment of 3 % and 1 %. The income related, increased tax and health care payments were used to cover the costs. Results and conclusions: In options (1) and (2) there were favorable cost-effective ratios. The practice-based option 3 was economically less promising. The higher the prevalence was, the higher the resulting cost-effectiveness.Hintergrund und Zielsetzung: Pro Jahrgang sind in Deutschland ca. 750.000 Kinder auf visuelle Entwicklungsstörungen zu untersuchen, wofür die konventionellen U-Vorsorgeuntersuchungen nicht ausreichend effektiv sind. Ziel der Untersuchung war es, den wirtschaftlichen Nutzen für die Sozialgemeinschaft von Alternativen der Amblyopie- und der Mikrostrabismusfrüherkennung im Alter von 24–48 Monaten zu untersuchen. Methode: Es wurden 3 Vorsorgeoptionen modellhaft verglichen: Option 1, eine orthoptische Untersuchung, welche vor Ort, z. B. im Kindergarten, eingesetzt wird; Option 2, eine untersucherunabhängige, gerätegestützte objektive Methode, ebenfalls vor Ort; Option 3, eine augenärztliche Untersuchung in der Praxis. Die Kosten von Früherkennung, Nachuntersuchungen und Behandlung in den 3 Optionen wurden für Prävalenzen amblyogener Faktoren von 1 % (kosmetisch unauffälliges Schielen) und von 5 % (allgemeine Amblyopierate) berechnet. Der „Ertrag“ durch die Behandlung wurde als Vermeidung einer verdienstrelevanten MdE von 3 % bzw. 1 % ermittelt. Die Steuer- und Beitragsmehreinnahmen der gesetzlichen Krankenversicherung wurden eingesetzt, um die Kosten der Vorsorgeprogramme zu decken. Ergebnisse und Schlußfolgerungen: Es wurden für die Optionen 1 und 2 günstige Nutzen-Kosten-Verhältnisse gefunden. Die praxisbasierte Option 3 war dagegen weniger kosteneffektiv. Das Nutzen-Kosten-Verhältnis fiel um so günstiger aus, je höher die Prävalenz war.

Self-assessment of angles of strabismus with photographic Purkinje I and IV reflection pattern evaluation

Abstract• Background: Accurate assessment of the angle of strabismus, e.g. of variable angles of strabismus, is crucial in preoperative patient management and is usually performed in a clinical environment. Objective assessment by patients themselves, under everyday conditions, could contribute to a better preoperative work-up. A new objective evaluation procedure for the measurement of manifest angles of strabismus for near and distance fixation by the patient himself is presented. • Methods: To account for the modified experimental setup used for the self-assessment, an amended computation procedure of Purkinje reflection pattern evaluation was developed. For measurement, patients and controls placed their head on a head/chin rest and fixated at 33 cm or 4 m distance in primary position. A reflex camera and three photo flash units were positioned on a special frame underneath the visual axis and in front of the subject so that both eyes could be photographed simultaneously. The cameras remote shutter control was released together with the photo flash units by the properly fixating subject. The angles of strabismus were obtained from the series of pictures through later evaluation of the Purkinje I and IV reflection patterns recorded in the photographs of the eyes.• Results: Measurements of the ocular alignment in two control groups and in a group of strabismic subjects showed satisfactory accuracy of the “self-assessment” method compared to “standard” Purkinje reflection pattern evaluation and orthoptic measurements of the angle of strabismus.• Conclusion: The modified “self-assessment” method can be used for the objective recording of angles of strabismus as needed in the preoperative work-up of patients with variable angles of strabismus, over prolonged periods of time, and outside a clinical setting.

Automatische Augenstellungsbestimmung in Infrarot-Videobild-Sequenzen

In diesem Artikel soll ein Verfahren vorgestellt wer-den, mit dem genau, robust und schnell die Augenstellung beider Au-gen einer Person objektiv bestimmt werden kann, um eine dynamische Schielwinkelmessung durchzufuhren. Das Verfahren wird erfolgreich in der Augenheilkunde eingesetzt.