Some observations on chronic closed-angle glaucoma.

AT WHAT stage in its course closed-angle glaucoma may be said to have become chronic is difficult to define. When, however, pathological cupping of the optic disc and visual field loss have occurred in an eye with closedangle glaucoma, the disease may reasonably be said to have reached the chronic stage. The aqueous outflow in such an eye is usually regarded as being permanently impaired by the development of goniosynechiae. It is the purpose of this communication to show that, in some cases, this advanced stage of chronic closed-angle glaucoma may result from closure of the filtration angle by irido-corneal contact alone, Without the development of either synechiae or permanent trabecular change. Barkan (1938) has stated that contact between the root of the iris and the entrance to the angle will, if transient, result in a rise of pressure of short duration; if the contact be not soon relieved by medication or operation, permanent organic adhesions will result. Grant (1951) has shown that periods of transient closure of the angle are associated with periods of reduced outflow of aqueous. It has already been suggested (Phillips, 1956) that, in cases of "subacute" closed-angle glaucoma, the uppermost part of the angle of the anterior chamber is closed by irido-corneal contact before any attacks of hypertension occur, and that the area so obstructed advances downwards nasally and temporally until a critical amount of angle remains open below, the lowermost limits of this obstruction varying from time to time depending on such factors as pupillary dilatation. While closure of the angle in cases of subacute closed-angle glaucoma was being investigated by means of the darkroom-outflow test (Foulds, 1956), it was noted that in certain cases the facility of aqueous outflow, measured by tonography (Grant, 1951), was lower than normal at the start of the test, although the ocular tension was within the accepted limits of normality. Moreover, the facility of aqueous outflow could be further reduced by a period in the dark, or could be increased by the instillation of a miotic, indicating an obstruction to aqueous outflow of variable degree. The following example illustrates this.