The student's guide to diseases of the eye . becomes verypale. — Althoughusually the excava-tion extends fromthe first over thewhole surface of thedisc, it appearssometimes to beginat the thinnest part(the physiologicalpit), and spread cen-trifugally thencetowards the border(p. 238). A deepcup is sometimespartly filled up byfibrous tissue, theresult of chronicinflammation, and its true dimensions are not then appreciable by theophthalmoscope. The shallowness of the anterior chamber is pro-bably due to advance of the lens ; it is by no meansa constant symptom. Compression of the ciliarynerves a
The student's guide to diseases of the eye . becomes verypale. — Althoughusually the excava-tion extends fromthe first over thewhole surface of thedisc, it appearssometimes to beginat the thinnest part(the physiologicalpit), and spread cen-trifugally thencetowards the border(p. 238). A deepcup is sometimespartly filled up byfibrous tissue, theresult of chronicinflammation, and its true dimensions are not then appreciable by theophthalmoscope. The shallowness of the anterior chamber is pro-bably due to advance of the lens ; it is by no meansa constant symptom. Compression of the ciliarynerves accounts, in early cases, for the dilated andsluggish pupil, and for the corneal anaesthesia. Inold-standing cases the iris is often atrophied andshrunken to a narrow rim; in uncomplicated glau-coma iritic adhesions are never seen. The cornealchanges depend partly on steaminess of the epi-thelium, partly upon haze of the corneal tissue fromoedema (Fuchs). In recent cases, especially if acute,the aqueous humour and the lens appear to become. Fig. 92. — Ophthalmoscopic appear-ance of deep cupping of the disc inglaucoma (altered from Liebreich).x about 15. 2U GLAUCOMA somewhat turbid. In old cases, as already stated,the lens often becomes slowly cataractons. It isgenerally stated that the vitreous humour becomeshazy during the attacks, especially in severe cases,but since it is just in these cases that the cornea andaqueous are most dull, the statements about thevitreous are conjectural (p. 235). The internal pres-sure tends, in acute cases, to make the globe spheri-cal, by reducing the curvature of the cornea to thatof the sclerotic; it also in all cases weakens theaccommodation, at first by pressing on the ciliarynerves, later by causing atrophy of the ciliary mus-cle ; these facts together explain the rapid decreaseof refractive power (i. e. rapid onset or increase ofpresbyopia) which is sometimes noticed by thepatient (p. 237).—The choroidal circulation is ob-structed by
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