Continued
So far, we have discussed problems associated only with the ‘outer eye’ (the eyelids, the cornea, etc). There are several other conditions which have to do with the ‘inner’ eye, and which could impair vision. In fact, any situation which will decrease the possibility of light entering the eye and falling upon the retina (that layer of cells at the back of the eyeball, on the inside), would have impaired sight as a result.
A few examples: Glau-coma (increased pressure within the eyeball), retinal damage, optic nerve damage, cataracts, and so on. Of course, other extraneous factors, like a vitamin A deficiency or a blow which dislocates the lens, or brain damage could have a negative influence on sight.
Glaucoma
This is a condition of the inner eye whereby there is an increased fluid pressure within the eyeball (intraocular). Most smart books consider glaucoma to be a symptom (rather than a disease in itself) of a more fundamental problem. Some authors document that glaucoma damages the retina and optic nerve. Others relate that glaucoma is a result of an already damaged optic nerve, the blood supply to which has decreased. Really, the absolute cause and pathology of this malady are obscure.
Glaucoma is
associated with:
i) The obstruction of the drainage system within the eye (fluid continues to be secreted, but is not drained away via ducts/canals).
ii) Cases of retinal atrophy.
iii) Cases of lens damage.
iv) Problems within the front chamber of the eye (neoplasms, haemorrhages, etc)
v) Reduced blood supply to the optic nerve and retina.
The symptoms are:
i) Swelling/bulging of one or both of the eyes.
ii) A permanently dilated pupil giving rise to a fixed, blank, unseeing stare.
iii) Hazy, steamy appearance of the cornea.
iv) Painful to the touch.
v) Excessive tears.
vi) Blood vessels on the eyeball are quite visible and full of blood.
vii) Squinting.
viii) Eventual blindness.
Actually, glaucoma can be divided into two types – primary and secondary. The primary glaucoma is congeni-tal. The problem in this case is genetic; the puppy is born with the glaucoma. Certain breeds like the American Cocker Spaniel, Wire-haired Terriers, Poodles and Basset Hounds seem to be good examples of the congenital glaucoma. Usually, the glaucoma is of the ‘secondary’ type. This means that the glaucoma is an acquired intraocular problem (see above) that interferes with the fluid flow.
Since high intraocular pressure can permanently damage the eye within a few days, acute glaucoma must be treated as an emergency.
Treatment
The treatment is designed to reduce the fluid build-up, therefore reducing the pressure within the eyeball. This can be achieved with medication or by surgery. Therapy for secondary glaucoma varies with the response to medication, and whether the secondary cause (eg tumour in the eyeball) can be removed surgically. In truth, radical surgery (removal of the eyeballs) is often the only way to proceed, since normal pressures cannot be consistently maintained medically for more than 2-3 days in dogs/cats.
Glaucoma must be seen as a very serious emergency. Owners are asked to seek veterinary help immediately. This is not one of those diseases with which you can ‘titivate’ at home.
See you next week.
Please implement disease preventative measures (vaccinations, routine dewormings, monthly anti-heartworm medication, etc) and adopt-a-pet from the GSPCA’s Animal Clinic and Shelter at Robb Street and Orange Walk, if you have the wherewithal to care well for the animals. Do not stray your unwanted pets, take them to the GSPCA’s Clinic and Shelter instead. If you see anyone being cruel to an animal, or if you need any technical information, please get in touch with the Clinic and Shelter by calling 226-4237.
