The student's guide to diseases of the eye . t isusually greatest in syphilitic iritis, when distinctnodules of pink, or yellowish, colour are sometimesseen projecting from the front surface. In rare casespus thrown out by the iris into the aqueous, subsidesand forms hypopyon; a corresponding deposit ofblood constitutes hyphsema. Firm adhesions to thelens-capsule may be present without much evidenceof exudation into the structure of the iris. Exudativechanges are usually most abundant at the inner ringof the iris, where its capillary vessels are far themost numerous (Fig. 51). Apparent discolo
The student's guide to diseases of the eye . t isusually greatest in syphilitic iritis, when distinctnodules of pink, or yellowish, colour are sometimesseen projecting from the front surface. In rare casespus thrown out by the iris into the aqueous, subsidesand forms hypopyon; a corresponding deposit ofblood constitutes hyphsema. Firm adhesions to thelens-capsule may be present without much evidenceof exudation into the structure of the iris. Exudativechanges are usually most abundant at the inner ringof the iris, where its capillary vessels are far themost numerous (Fig. 51). Apparent discoloration of the iris is, however,often due entirely to suspension of blood-corpuscles,or inflammatory products, in the aqueous humour;sometimes this altered fluid coagulates into a slightly 116 IRITIS turbid gelatinous mass, which almost fills the chamber(spongy exudation). The aqueous sometimesbecomes yellow without losing transparency. The tension of the eyeball may be a little increasedin acute iritis; rarely it is considerably diminished,. Fig. 51.—Vessels of human iris artificially injected ; capillariesmost numerous at pupillary border, and next at ciliary border. and in such cases there are generally other pecu-liarities. The condition of the pupil alone is diagnostic inall except very mild or incipient cases of iritis. Itis sluggish or quite inactive, and not quite round; itis also rather smaller than its fellow (supposing theiritis to be one-sided), because the surface of the irisis increased (and the pupil, therefore, encroached on)whenever its vessels are distended (p. 29). Atro-pine causes it to dilate between the synechiee; thesynechiae, being fixed, appear as angular projectionswhen the iris on each side of them has retracted. If IRITIS 117
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