CHAMBER DEPTH IN SIMPLE GLAUCOMA

In primary acute glaucoma the anterior chamber is with few exceptions very shallow; from this fact has developed the theory of angle-closure being the mechanism of the rise in pressure. On the contrary in simple glaucoma another mechanism is suggested because the anterior chamber is considered by most authorities to be of normal depth. Should it not be so, then we must reconsider whether there is sufficient evidence for such a clear-cut differentiation between the two diseases. Only a few earlier studies of the variation of chamber depth in simple glaucoma have been made. Raeder (1923) measured with his own method the distance from the anterior corneal surface to the pupillary margin in 70 cases of primary chronic glaucoma. These cases were characterized by an insidious course, and corneal clouding and congestion was absent except for a dilatation of the anterior ciliary vessels in some cases. The chamber depth was, on an average, a little smaller than in normal emmetropes in the same age group, but the difference was slight. The distribution curve showed a comparatively increased number of cases with shallow chambers. If ten cases were removed where the disease was far advanced and the visual acuity completely or nearly lost, a mean value for the rest of the group was obtained which did not differ much from the original. The advanced cases showed the same distribution as other cases. Thus, it was considered improbable that the chamber depth in the later stages of the disease is essentially reduced. A correlation between the intraocular pressure and the chamber depth did not exist. Raeder considered that primary chronic glaucoma is probably not a uniform group but comprises two pathogenetically different types of disease, one of which is associated with a shallow chamber and the other with a normal or deep chamber. Rosengren (1931) found, when measuring 104 glaucoma cases of different types with Lindstedt's apparatus, a smaller average chamber depth than in a