Hypopyon

HYPOPYON (from Greek hypo — below and pyon — pus), an accumulation of pus in the anterior chamber of the eye, descending by gravity to its floor [see separate plate (pp. 303–304), Fig. 1]. The semi-fluid pus moves slowly when the head is tilted, occupying a horizontal position. With a greater admixture of fibrin, the pus becomes pasty or even forms a true lump of pus, no longer changing its outlines and position when the head is tilted. Hypopyon does not represent an independent disease, but is a symptom of purulent

Schematic section of the eye:

¹ — infiltrated margin of the ulcer;

— lower margin of the ulcer;

— purulent lump behind the ulcer in the anterior chamber;

4 — hypopyon. inflammatory cells, mainly originating from the vessels of the iris and ciliary body, settle and form hypopyon. Proof that the pus elements originate from the anterior sections of the uveal tract is the presence of pigment granules, free and attached to the pus cells, detected by microscopic examination of the chamber fluid obtained by puncture. Hypopyon is one of the constant and characteristic phenomena in serpiginous corneal ulcers (whence the name hypopyon-keratitis), and the larger the ulcer, the more the upper level of the hypopyon loses its horizontal and rectilinear direction and begins to bulge toward the center of the ulcer. With a high hypopyon, it is difficult to distinguish its boundaries from the infiltration around the corneal ulcer, especially since pus cells also settle on the posterior surface of the cornea opposite the ulcer, forming entire accumulations there. The latter, increasing in size, descend downward and eventually merge with the hypopyon (see figure). The thinner the pus, the faster it is absorbed (sometimes within a day). Dense pus is absorbed slowly and may even organize in the anterior chamber, closing the pupillary area or causing the iris to adhere to the posterior surface of the cornea (rarely). But although pus can resolve under the influence of conservative therapy with improvement of the process in the cornea, nevertheless, in cases where the hypopyon is very large and fills most of the anterior chamber, it is a serious complication and must be removed by surgical intervention — Saemisch section of the ulcer or trephination. Aside from ulcerating processes in the cornea (and, less frequently, infected wounds of other eye tissues), i.e., apart from exogenous infection, hypopyon can also form in endogenous infection, when pyogenic pathogens are brought by the blood and localize mainly in the vascular tract of the eye. As a clear indicator of the presence of severe infectious diseases in the eye, and moreover an indicator that fluctuates with the improvement or worsening of the underlying process, hypopyon is of great importance for the prognosis of the underlying disease.

Author signature: A. Pokrovsky