Excerpt from Hyphema

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Postinjury accumulation of blood in the anterior chamber is one of the most challenging clinical problems encountered by the ophthalmologist. Even a small hyphema can be a sign of major intraocular trauma with associated damage to vascular and other intraocular tissues. Blunt trauma to the eye may result in injury to the iris, papillary sphincter, angle structures, lens, zonules, retina, vitreous, optic nerve, and other intraocular structures. Blunt trauma associated with a rapid, marked elevation in intraocular pressure with sudden distortion of intraocular structures produces the dynamic changes responsible for hyphema formation. The lack of an ideal therapeutic program, the potential for secondary hemorrhage, and the secondary onset of glaucoma all threaten to turn an eye with an initially good visual prognosis into a complex therapeutic problem with a poor final visual result.

Classification and characteristics

Traumatic hyphema is encountered in children and adults. The agent producing a hyphema is usually a projectile that strikes the exposed portion of the eye. Various missiles and objects have been incriminated, including balls, rocks, projectile toys, air gun pellets, BB gun pellets, hockey pucks, bungee cords, paint balls, and the human fist (Morris, 2006; Listman, 2004). With the increase of child abuse, fists and belts have started to play a prominent role. Males are involved in three fourths of cases (Crouch, 1976; Edwards, 1973).

Rarely, spontaneous hyphemas may occur and be confused with traumatic hyphemas. Spontaneous hyphemas are secondary to neovascularization (eg, diabetes mellitus, ischemia, cicatrix formation), ocular neoplasms (eg, retinoblastoma), and vascular anomalies (eg, juvenile xanthogranuloma). Vascular tufts that exist at the pupillary border have been implicated in spontaneous hyphemas (Podolsky, 1979).

The following clinical grading system for traumatic hyphemas is preferred:

• Grade 1 - Layered blood occupying less than one third of the anterior chamber
• Grade 2 - Blood filling one third to one half of the anterior chamber
• Grade 3 - Layered blood filling one half to less than total of the anterior chamber
• Grade 4 - Total clotted blood, often referred to as blackball or 8-ball hyphema

Most hyphemas fill less than one third of the anterior chamber. When hyphemas are divided into 4 groups according to the amount of filling of the anterior chamber, 58% involve less than one third of the anterior chamber, 20% involve one third to one half of the anterior chamber, 14% involve one half to less than total of the anterior chamber, and 8% are total hyphemas. Slightly fewer than one half of all hyphemas settle inferiorly to form a level; approximately 40% form a definite clot, usually adherent to the iris stroma; and 10% have a dark clot in contact with the endothelium. This last form may portend a poor outcome and corneal staining.

An alternative method of grading hyphemas involves measuring (in millimeters) the hyphema from the inferior 6-o'clock limbus. This method may help in monitoring the progress of resolution or the occurrence of rebleeding. Digital imaging analysis is also useful and objective but is available in only a few research or academic facilities.

The cause of an anterior chamber hemorrhage in contusion injuries is thought to be related to the posterior displacement of tissue or to the resultant fluid wave in the aqueous humor and the vitreous. This sudden dynamic shift stretches the limbal vessels and displaces the iris and the lens. This displacement may result in a tear at the iris or the ciliary body, usually at the angle structures (Hoskins, 1978). A tear at the anterior aspect of the ciliary body is the most common site of bleeding and occurs in about 71% of cases (Read, 1974). The blood exits from the anterior chamber via the trabecular meshwork and the Schlemm canal or the juxtacanalicular tissue.

The usual duration of an uncomplicated hyphema is 5-6 days. The mean duration of elevated intraocular pressure is 6 days.

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