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Persistent Pupillary Membrane
During the embryonal phase, the "pupil" of the primitive iris tissue is covered by a membrane, the pupillary membrane. This membrane begins to regress about two weeks before birth and has completely disappeared by 2 to 4 weeks after birth. Occasionally remnants of this membrane remain as congenital defects.
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As the term indicates, persistent pupillary membrane is a condition in which the delicate membrane covering the anterior surface of the lens during the greater part of the intrauterine life, fails to undergo complete resolution and persists as fibers, either singly or in strands, passing across the pupil, or slightly opaque membrane floating or adherent to the capsule of the lens.
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These strands, or "threads", sometimes resemble a spider's web in the eye. They can also attach to the cornea and cause scars there.
The condition seems to hereditary in some cases. Where but a few fibers persist, vision is not impaired and their presence is usually unnoticed until some disorder prompts close inspection of the eye.
But where the membrane persists as such the dog experiences difficulty in seeing, particularly in bright light. This condition may be found alone or in combination with other eye defects.
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Treatment
Strands and floating membranes can be removed surgically.
References:
1. Medical History and Physical Examination in Companion Animals
by Adam Rijnberk
2. Medical History and Physical Examination in Companion Animals By Adam Rijnberk, H. W. de Vries
Go Pets America recommends seeking the advice of your local veterinarian for the most appropriate vaccination program and for the diagnosis and treatment of your pet's health problems. For vaccination requirements please contact your state and local licensing authorities.
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