Cataracts are more prevalent in Abyssinian guinea pigs but can affect all species. The cause is not known. The lens of the eye gradually becomes more cloudy but the guinea pig learns to manage with its decreasing vision and surgery is not recommended as current opinion considers the risks and trauma outweigh the benefits.
Sudden cloudiness or an opaque covering on the surface of the eye is more likely to be caused by a foreign body or injury such as a scratch. The eye clouds over to allow itself to heal.
Association of Optometrists article Optometry PDF on Human Cataracts and Nutrition
Conjunctivitis is an infection of the eye, normally caused by opportunist bacteria entering a small wound in the eye or in the eyes of animals who’s immune systems are already compromised. Eye infections and injuries should always be checked out and treated by your veterinary surgeon.
If you suspect a foreign body is in the eye, irrigate the eye with saline irrigation solution (available in sachets from chemists or drug stores) or colloidal silver to allow the object to float to the surface. Wet your finger and sprinkle it with a little pepper or cinnamon then hold it under the rabbit or guinea pig’s nose to make it sneeze the object out sometimes works. Don’t get the powder on its nose though as it is an irritant to the delicate mucus membranes. Some grass seeds have small barbs or hooks which make removal difficult. If in any doubt get your vet to check it out.
Runny eyes can be related to dental problems, draughts, allergies to bedding, ammonia from urine, urine spraying by another guinea pig, an infection, injury or foreign body. They may also be the result of scratching by long, broken and dirty nails especially on the back feet which are commonly used to scratch the face. All these will have to be checked out.
Guinea pigs produce a milky white fluid from their eyes as a natural part of the grooming process, this is especially apparent after bathing them.
Dental problems can be checked out by looking at the incisors or front teeth which, if not normal, might indicate problems with the back teeth or molars. Ears which wiggle a lot when the animal eats are also an indicator of dental problems.
Allergies can often be resolved by changing the litter and bedding used. Galen’s Herbal Tincture Blend No.III contains a blend of herbs which may help. Luke warm chamomile tea or homoeopathic eyebright mother tincture in water (See Homoeopathy) as a soothing eye wash. Colloidal Silver is a valuable first aid treatment for sore or infected eyes. Spray into the eye several times a day.
In some guinea pigs a portion of the lower eyelid sags revealing a layer of fat underneath. It is a harmless condition and believed to be hereditary. A connection between fatty eye and heart problems has been suggested based on observation that in some guinea pigs treated with the diuretic drug Lasix for suspected heart conditions, the fatty eye condition also improved. However not all guinea pigs treated with Lasix show an improvement in fatty eye. See article on Treen’s Pigs site.