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Priestley Smith has pointed out that the glaucomatous eye softens more slowly than the normal eye after enucleation, in spite of the fact that a greater force is operating to drive fluid out of the eye.
It seems that both of these theories afford an explanation for many of the secondary pathological manifestations which characterize the intra-ocular tissues during a glaucomatous onset. Fischer criticizes the Henderson theory on the ground that increased blood pressure alone does not lead to edema edema is thwarted by high blood pressure.
However, the change in the position of the lamina cribrosa must exert a deleterious effect, particularly on those fibers which pass through the peripheral meshes, the shape of which must necessarily be much distorted. XLII. p. 145; Opin. Soc. Arteries and veins are both affected. Hyaline degeneration of the media also occurs. The process is not uniform. Glaucomatous Cup.
The development of the pale circle which surrounds the disc, particularly in glaucomatous eyes, is due to a very slight recession of the pigment layer of the retina and of the margin of the chorioid at this point with some atrophy, apparently consequent on the beginning retraction of the lamina cribrosa and slightly increased pressure of the nerve fiber layer on the underlying tissues at the margin of the disc.
As has been shown by Priestley Smith, the cornea in glaucomatous eyes is, as a rule, smaller than in non-glaucomatous eyes, the mean of a series of measurements being 11.1 mm. horizontally and 10.3 mm. vertically in glaucomatous and 11.6 mm. horizontally and 11 mm. vertically in non-glaucomatous eyes.
For nine years I have watched the progress of such a glaucoma in a man now aged 87, with slow development of glaucomatous cupping of the optic disc, now more than 3 D. deep. Similar cases in which the tension lay within the commonly accepted normal limits have been reported recently by Bietti and Stock.
In a few instances endeavor has been made to reduce the intra-ocular tension, or at least to relieve glaucomatous symptoms, by galvanism of the cervical sympathetic, for example, by placing one electrode along the whole length of this nerve in the neck and one on the back of the neck on the opposite side, 15 to 20 ma. of current being used.
It affords a possible mechanism through which may be produced the recognized glaucomatous effects of certain nerve disturbances. But such attacks are not commonly associated with noticeable flushing of the head and face generally; and paralysis of the cervical sympathetic is known to lower the intra-ocular tension.
In his recent tonometric studies Schoenberg noted that under manipulation the glaucomatous eye softened more slowly than the normal eye; and suggests this diminished drainage as an important evidence of glaucoma. Obstructed outflow might begin in an abnormal tendency of the tissues to retain fluid, a tendency that Fischer might locate in the colloids.
I am firmly convinced that every glaucomatous patient, and I now refer to those who are the subjects of chronic progressive glaucoma, should be carefully studied from the general standpoint by the oculist with the aid of an expert internist, just as I am convinced that the modern expert internist should not study his cases of cardio-vascular disease without the help of the oculist.
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