Excerpt from Hyphema, Postoperative

Synonyms, Key Words, and Related Terms: postoperative hyphema, surgical hyphema, gross hyphema, microscopic hyphema

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Background: Surgical hyphema is a known risk of intraocular surgery. Hyphema is the presence of red blood cells in the aqueous humor of the anterior chamber. It can be classified as gross hyphema or microscopic hyphema. Gross hyphema can be graded according to the level of blood meniscus in the anterior chamber of the eye. The term microscopic hyphema applies to red blood cells (erythrocytes) that are only visible on careful slit lamp biomicroscope examination with a narrow beam.

The clinical grading system for hyphemas is as follows:

Grade I - Layered blood occupying less than one third of the anterior chamber
Grade II - Blood filling one third to one half of the anterior chamber
Grade III - Layered blood filling one half to less than total of the anterior chamber
Grade IV - Total clotted blood, often referred to as blackball or 8-ball hyphema

Pathophysiology: Hyphema describes the condition of the aqueous humor when red blood cells form a suspension in it. The layer of the globe between the retina and the sclera is called the choroid. The choroid and the iris are both part of the uveal tract. The ciliary body is mesenchymal in origin and is located immediately posterior to the iris at the junction of the iris root and the posterior choroid. The retina inserts at the pars plana into the ciliary body. The choroid and the iris contain a rich complex of vessels. The pupil is outlined and controlled by a complex set of iridial muscles, sphincters and dilators. These muscles can be ruptured by sharp and/or blunt trauma. This is a frequent source of intraocular hemorrhage (hyphema). In addition, the iris root and/or the ciliary spur is a common location of bleeding from blunt trauma.

Surgical intervention into the eye for anterior segment procedures is accomplished routinely through various approaches. The most commonly used approaches in modern small incision surgery are via the limbus and/or clear cornea. Clear cornea surgery markedly reduces the risk of bleeding from limbal vessels since the cornea in its healthy state is avascular. Scleral tunnel incision is subject to unpredictable hemorrhage, and the incision must be closed carefully with sutures. Self-sealing wounds can be problematic at times, with unexpected hyphema occurring up to 10% of the time.

Hyphema can occur as a result of intraocular surgery, as follows:

Intraoperative bleeding - Ciliary body or iris injury seen during a peripheral iridectomy, cataract extraction, cyclodialysis, and filtration procedure (laser peripheral iridectomy, especially with YAG laser than with the argon laser; argon laser trabeculoplasty [ALT] not very common)
Early postoperative bleeding (a traumatized uveal vessel that was in spasm and suddenly dilates; conjunctival bleeding that makes its way into the anterior chamber via a corneoscleral wound or sclerostomy)
Late postoperative bleeding (new vessels growing across the corneoscleral wound that bleed when manipulated; a uveal wound that is reopened; an intraocular lens [IOL] that causes chronic iris erosion)

Frequency:

In the US: The incidence of hyphema is 17-20 per 100,000 people per year.

Mortality/Morbidity: Most postsurgical hyphemas are self-limited. They generally tend to be asymptomatic and usually do not cause an extreme elevation of intraocular pressure (IOP). In cases in which the hyphema reduces vision or causes elevated IOP, conservative medical therapy usually allows for resolution of the hyphema. Patients who have had recent glaucoma surgery and develop a hyphema need to be monitored closely. Blood can be a stimulus for early bleb failure.

Race: Patients with African American ancestry may require closer care because they may have sickle cell trait or disease and, .....