Examination of the anterior chamber of the eye is performed by a veterinarian or veterinary ophthalmologist as part of a thorough ophthalmic exam. The anterior chamber is located between the endothelium (the innermost cellular layer) of the cornea and the iris. The aqueous humor is a liquid which fills the anterior chamber.
Glaucoma is one of the most common diseases of the anterior chamber and occurs when the normal outflow of the aqueous humor from the anterior chamber is blocked leading to an increase in intraocular pressure. Hyphema is also common and is defined as blood within the aqueous humor.
Things You'll Need
- Slit lamp or direct ophthalmoscope
- Tonometer
- Goniolens
Instructions
Use a handheld slit lamp or a direct ophthalmoscope with a small spot or slit setting as a light source. In a darkened room, place the light source close to the eye and focus the light on the cornea. Examine the anterior chamber at an angle perpendicular to the light source.
Look for changes in the turbidity of the aqueous humor indicative of aqueous flare which occurs with increased protein levels or cells within the anterior chamber. Also look for evidence of cellular accumulation such as hyphema (blood in the anterior chamber) or hypopyon (pus in the anterior chamber). Finally, examine the face of the iris for changes in color, shape or texture.
Evaluate the aqueous humor for opacities using retroillumination. Standing at arm's length from the dog, obtain a tapetal reflex with the direct ophthalmoscope or slit lamp. A tapetal reflex is a reflection of light off of the retina causing the eyes to glow when illuminated by a light in a darkened environment. Any opacities will block or decrease the tapetal reflex.
Measure the intraocular pressure with a tonometer by first placing a drop of a local anesthetic such as proparacaine into the eye. Hold the head steady and rest the tonometer on the cornea of the eye. The tonometer flattens the cornea and measures the degree of indentation in millimeters. A reading greater than 25 millimeters indicates elevated intraocular pressure.
Perform a gonioscopy examination to examine the iridocorneal angle, the angle formed where the bases of the iris and cornea meet. Place the goniolens on the cornea of the eye and use the slit lamp or the ophthalmoscope to illuminate the eye and examine the angle. Look for the presence of tumors, foreign bodies, inflammatory exudates or blood.