Primary angle closure glaucoma: a review of ocular biometry

Abstract

Pupil block angle closure glaucoma is a multifactoral disease. Shallowness of the anterior chamber is a valuable clinical sign that is capable of accurate measurement by commercially available pachymeters attached to slitlamps. Shallowness of the anterior chamber is mainly the result of polygenic inheritance and in this respect the predominant feature is anterior siting of the lens, with increased lens thickness being less important. To the genetic basis is added a progressive shallowing of the anterior chamber that occurs during adult life. This is caused almost entirely by increasing lens thickness with more forwards positioning of the lens being almost insignificant. A threshold for risk of pupil block angle closure glaucoma occurs at 2.5 mm of anterior chamber depth. The means of almost all biometric studies on eyes with angle closure glaucoma show a significant difference from the means of similar measurements on eyes in the general population, but in the general population many people are carriers of the physical features of primary angle closure glaucoma without developing the disease.