The eye continuously produces a fluid called aqueous humor, which maintains eye shape and nourishes internal structures. This fluid must drain properly through the iridocorneal angle to maintain normal eye pressure. If this drainage angle is abnormally narrow, malformed, or partially closed, fluid outflow is restricted, leading to increased pressure inside the eye and a higher risk of glaucoma.
Gonioscopy is the only clinical method that allows direct visualization of this drainage angle. During the procedure, a veterinary ophthalmologist applies a local anesthetic to the eye and places a special magnifying contact lens called a gonioscope on the cornea. This enables detailed examination of the internal drainage structures under magnification and controlled lighting.
This test is especially important in breeds predisposed to Primary Angle-Closure Glaucoma (PACG) or other inherited forms of glaucoma, where anatomical abnormalities of the drainage system may be present long before clinical signs appear. Early identification of abnormal angles allows veterinarians and breeders to implement preventive monitoring strategies.
Clinical signs of glaucoma often do not appear in the early stages. When the disease progresses, dogs may develop symptoms such as eye redness, squinting, excessive tearing, cloudy cornea, enlarged eyeball (buphthalmos), and vision loss. Because damage caused by glaucoma is irreversible, early detection of structural risk through gonioscopy is extremely important.
The Gonioscopy (PLA) Eye Test is performed by a qualified veterinary ophthalmologist as part of a comprehensive eye examination. It is often combined with tonometry (intraocular pressure measurement) and slit-lamp biomicroscopy to assess overall eye health and function.
Results of gonioscopy are generally categorized as:
- Normal Drainage Angle: Open and functional drainage system with low risk of primary glaucoma.
- Mild Narrowing: Slight reduction in drainage angle width, indicating increased risk and need for monitoring.
- Moderate Abnormality: Noticeable narrowing or structural irregularity, associated with higher glaucoma risk.
- Severe Abnormality (High Risk): Significant angle closure or malformation, strongly predisposing the dog to glaucoma.
Gonioscopy is highly valuable for breeders, veterinarians, and dog owners. For breeders, it is recommended that breeding dogs undergo gonioscopic screening at least once before breeding to identify those with normal drainage angles and reduce the risk of passing on anatomical predisposition to glaucoma. This helps improve long-term eye health in future generations.
For dog owners, gonioscopy provides important preventive information about eye health. Dogs identified as high risk require regular monitoring so that early signs of increased intraocular pressure can be detected and managed promptly. While gonioscopy does not treat or prevent glaucoma, it plays a crucial role in early risk identification and long-term eye care planning.
The Gonioscopy (PLA) Eye Testing is a vital ophthalmic screening tool that supports early detection of glaucoma risk, improves breeding decisions, and helps protect lifelong vision health in dogs.
