Closed-Angle Glaucoma: A Study of the Mechanism of Angle Closure

Foulds, Wallace S (1958) Closed-Angle Glaucoma: A Study of the Mechanism of Angle Closure. PhD thesis, University of Glasgow.

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Abstract

Presented in this thesis is a new conception of the mechanism underlying the development of closed angle glaucoma. It is based upon a study of the ocular tension and facility of aqueous outflow in normal eyes and those affected by the disease, in response to provocative tests, together with observations upon cases of chronic closed angle glaucoma and upon the apparently healthy eyes of cases wherein the disease is unilateral. The development of currently accepted views on the aetiology of closed angle glaucoma is traced in a review of the literature on the subject and it is shown that the disease is believed to be due to mechanical obstruction of the angle of the anterior chamber by the root of the iris in an eye wherein the lens is disproportionately large. It has been generally held until now that in an eye affected by this disease the ocular tension and facility of aqueous outflow between attacks of hypertension are completely normal and that the angle of the anterior chamber at these times is open and functioning freely. That this view is erroneous in in many cases, however, is the deduction to be drawn from the work presented in this thesis, for all the evidence supports the view that even in the early stages of the disease a variable portion of the angle of the anterior chamber is habitually closed and that the ocular tension and facility of aqueous outflow in such an eye, although still within the accepted limits of normality, is in fact already abnormal for the eye in question. The darkroom test is studied in detail and an analysis of the results of the test on normal eyes and those affected by closed angle glaucoma is presented. It is shown, contrary to the generally accepted view, that the rise in ocular tension occasioned by the test is influenced by the initial tension in the eye tested and probably by the degree of angle closure existing prior to the test. It is calculated that a rise in ocular tension of over 8.5 mm. Hg with the darkroom test is evidence in favour of a diagnosis of closed angle glaucoma. The development of the tonographic method of measuring the facility of aqueous outflow is outlined and and a new provocative test, the "darkroom outflow test" is described. In this test, measurements of the facility of aqueous outflow are made before and after one hour in the dark; the occurrence of angle closure being indicated by a measurable fall in the level of aqueous outflow. From a study of the results of this test on normal eyes and those affected by closed angle glaucoma it is concluded that a fall in the outflow level of at least 30% with this test is of significance. Contrary to the generally accepted view, it is shown that in cases of closed angle glaucoma, even where the resting ocular tension is within normal limits, the facility of outflow is lower than that found in comparable normal eyes, indicating the existence of some degree of angle closure in the affected eyes. It is also demonstrated that the rise in ocular tension occuring with the darkroom test is directly related to the level of aqueous outflow existing prior to the test and thus to the degree of angle closure present at that time. From a study of the effect of the darkroom test and the darkroom outflow test on normal eyes it is concluded, contrary to the generally accepted view, that variations in the rate of aqueous inflow play a more important part in the causation of changes in ocular tension than do alterations in the rate of aqueous outflow. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Ophthalmology
Date of Award: 1958
Depositing User: Enlighten Team
Unique ID: glathesis:1958-79258
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Mar 2020 11:13
Last Modified: 05 Mar 2020 11:13
URI: http://theses.gla.ac.uk/id/eprint/79258

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