, Volume 34, Issue 1, pp 413-434

Mesure optique de la profondeur de la chambre anterieure applications cliniques

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Abstract

The depth of the anterior chamber is measured with a coincidence ocular placed on the Haag-Streit slit lamp. The accuracy of the method is approximately 0.1 mm. The thickness of the lens, its position in the eye, and the length of the globe are measured by ultrasonic echography. The depth of the anterior chamber depends on the biometric characteristics of the cornea and of the lens. The height of the corneal apex depends on the diameter and on the curvature radius of the cornea. The role of the lens is determined by its thickness and its position.

In 2,395 normal eyes the depth of the anterior chamber is influenced by age, sex and refraction. Its depth is 2.5 mm. at birth, it reaches 3.25 mm. at the end of the growth and decreases to values smaller than 2.65 mm. after the age of 60.

This evolution depends on two factors which act in opposite directions: longitudinal growth of the eye increases the depth of the anterior chamber. This growth terminates at the age of 20. Increase of the lens thickness decreases the depth of the anterior chamber; this increase continues until death.

The depth of the anterior chamber is increased in axial myopia and decreased in hypermetropia. Different pathological factors increase the depth of the anterior chamber.

The increase of the ocular volume in high myopia is mostly retroequatorial and does not increase in the same proportion as the depth of the anterior chamber. Congenital glaucoma is characterized by considerable increase of the anterior chamber depth. This is partially the consequence of the distension of the globe under the influence of ocular hypertony. Some of the biometric disturbances of the cornea have the same effect : megalocornea and keratoconus.

Ectopia of the lens, subluxation, microphakia, senile cataracts, phakolysis, resorption of secondary cataracts, and aphakia are factors that increase the depth of the anterior chamber. Atropine mydriasis has the same effect.

Other factors that decrease the depth of the anterior chamber include microphthalmia, microcornea, corneal edema, forward subluxation of the lens, choroidal detachment pushing the lens forward, loss of the aqueous, and intumescence of the lens. Miotics decrease the depth of the anterior chamber.

Measurement of the anterior chamber is of practical interest in all these diseases. It helps recognition of a predisposition for close angle glaucoma because a shallow anterior chamber is a prerequisite condition for angle closure. Thus, installation of mydriatics may be contraindicated. It also aids in the diagnosis of small subluxations of the lens by comparing the chamber depth in both eyes. Finally, this method is useful in following the evolution of a senile or systemic cataract, and in monitoring the restoration of the anterior chamber after surgery.

Résumé

Description de la technique de mesure de la profondeur de la chambre antérieure. Valeurs chez le sujet normal en fonction de l'âge, du sexe et de la réfraction.

Enumération des facteurs oculaires, cornéens et cristalliniens susceptibles d'augmenter ou de diminuer la profondeur de la chambre antérieure. Considérations sur l'intérêt clinique de la mesure de la profondeur de la chambre antérieure pour le diagnostic, la thérapeutique médicale et chirurgicale et pour la prévention de certaines complications en cours de traitement ou dans le décours post-opératoire.

Adresse des auteurs: Clinique ophtalmologique de l'université de Liège, Hôpital de Bavière, 4000 Liège, Belgique.