The cornea is the clear, protective layer that covers the outside of your dog's eye. It is not uncommon for it to get scratched, especially if your dog frequently plays with pets in the household, especially cats. A cornea injury don't always lead to permanent damage, but you should have your dog examined by a veterinarian any time you suspect his eye is injured or irritated.
A scratched cornea can possibly lead to blindness, but the final outcome depends on several factors, including the extent of the initial damage. Shallow scratches typically heal without permanent damage to your dog's eye, especially if your dog is young. Deep scratches, however, can turn into corneal ulcers. If an ulcer goes far enough into the cornea, it can create a situation in which fluids from the inner eye leak out, resulting in permanent blindness. Scratches that are less than half the depth of the cornea are considered shallow, or superficial, while those more than half the depth are considered more serious and should be monitored closely by your veterinarian.
Healing and Infection
The most likely way for a scratch in your dog's cornea to result in blindness is for it to become infected. Swelling caused by an infection prevents the scratch from healing and can even make the abrasion larger and deeper than it was in the beginning. If the infection is stopped soon enough, your dog's eye may heal without any permanent effects. Depending on the depth of the scratch, however, his cornea may be scarred. An ongoing untreated infection is likely to result in blindness.
Signs and Symptoms
The first signs of a scratch on your dog's cornea include squinting, excessive blinking and watery eyes. The damage is also likely to feel painful and itchy for your dog, so he may paw or scratch at his eye. A creamy discharge may also accumulate at the corner of your dog's eye and the white of his eye could turn red due to the irritation. If the scratch becomes infected, the cornea may start to look cloudy.
Diagnosis and Treatment
Your veterinarian will use a fluorescein dye to reveal any damage to your dog's cornea. The dye settles in the scratch and washes away from the rest of the eye to allow the vet to examine the size and depth of the damage. Superficial scratches don't always require treatment and often heal in less than a week, but your veterinarian may prescribe drops to soothe your dog's eye if he seems to be experiencing discomfort. Your veterinarian will probably want to check your dog's eye again in a few days to make sure it has healed completely. Deep scratches may require surgery, or your veterinarian may opt to use pain-reducing and antibiotic drops while checking your dog's eye regularly to confirm that it is healing.