Turtles suffer from two distinct eye problems: swollen eyelids and bacterial eye infections. Swollen eyes effectively render the turtle blind, and this makes it difficult for the animal to feed itself, so that the turtle is at serious risk of starvation. Bacterial eye infections are develop on their own or together with swollen eyes. Because the bacteria can easily move from the eye to the nasal passages, if left untreated an eye infection can quickly lead to a potentially fatal respiratory tract infection.
Typical symptoms of swollen eyes include:
In mild cases, swollen eyelids will simply seem puffier than normal
Reddening of the conjunctiva and orbital (tear-secreting) glands
In more severe cases the eyelids become so swollen that the turtle cannot open its eyes, so is for all practical purposes blind
Weeping (excess tear production) is common, along with the accumulation of detritus (specifically dead cells) around the eye
Often the nose becomes blocked as well
When turtles cannot see, they cannot feed, so turtles suffering from swollen eyelids will stop eating and lose weight
Eye infections can occur on their own or in association with swollen eyes. Eye infections can also be connected with respiratory tract infections. Typical symptoms of eye infections include:
Reddening of the conjunctiva and surrounding tissues
Eye appears puffy and/or watery
Turtle frequently rubs or scratches its eyes
Look out for respiratory tract infections as well, such as wheezing, loss of proper balance when swimming, and excessive amounts of fluids coming from the nose and mouth
Any turtle with eye infection or swelling will need to be examined by a vet because confirming and treating these problems is beyond the ability of the average hobbyist. The vet will examine the Harderian glands for signs of swelling. If this is found, it is a good indicator that the immediate problem is Vitamin A deficiency (hypovitaminosis A) cause by a poor diet. In this case, the vet will give the turtle an immediate injection of Vitamin A to stabilise the condition, and then provide the pet owner with advice on how to improve the diet so that the turtle will recover.
Swollen eyelids can also be caused by a bacterial infection such as a respiratory tract infection, trapped sand or silt under the eyelid, physical trauma, or a variety of other problems. A vet familiar with reptiles will consider all these options and will check for them in turn, but a vet less familiar with reptiles might not. If in doubt, mention the alternatives to the vet, of only as a reminder!
Bacterial infections of the eye will be confirmed by sampling the mucous around the eyes using swabs. Once the precise infection is diagnosed, the vet will then prescribe suitable antibiotics, typically administered by an intramuscular injection.
Asymmetrical swelling of the eye (that is, one eye is puffed up but the other is not) is normally caused by physical damage. Because of the physical damage, a secondary infection behind the eye is causes the eye to bulge. This will need to be treated by a vet using an appropriate antibiotic. Left untreated, these infections can spread, frequently causing blindness and often killing the turtle.
Infections of the Eustachian tubes (the connecting tubes between the ears and throat) can also cause the eye to swell. Again, this requires veterinarian assistance.
Chlorinated water can irritate the eyes of aquatic turtles, causing them to wipe or scratch their eyes. All new water added to the vivarium should have the chlorine (and chloramine, if present) removed using dechlorinator of the sort sold for use in fish tanks.
Swelling of the eyelids is one of the first signs of Vitamin A deficiency. More specifically, the Harderian glands become swollen, and these cause the eyes to puff up. Eventually the eyelids become so swollen that the turtle cannot open its eyes at all, and effectively it becomes blind. Less apparent to the pet owner will be the other usual problems caused by Vitamin A deficiency, including kidney damage and, once the problem becomes terminal, swelling around the feet.
Eye infections are caused by a variety of bacteria most frequently Aeromonas and Pseudomonas spp. The vet will confirm this. Left untreated, eye infections can lead to septicaemia and respiratory tract infections. These can in turn eventually kill your turtle.
Swollen eyelids are a symptom of Vitamin A deficiency. While this is not normally a problem when a turtle is given a healthy, balanced diet, aquatic turtles (terrapins) are all too often given very inadequate diets lacking in fresh plant material.
Eye infections can have a variety of causes. Aquatic turtles often develop them when kept in dirty water. Eye infections can also be connected with other diseases, including swollen eyelids and respiratory tract infections.
Both swollen eyelids and eye infections need veterinarian help. Assuming that the Vitamin A deficiency has not reached a terminal stage, a full recovery can be expected. Normally the vet will give the turtle an immediate injection of Vitamin A, and then further improve the situation by prescribing Vitamin A drops that will need to be administered orally. The pet owner will also be expected to improve the turtle's diet to prevent a relapse. Bathing of the eye to alleviate the symptoms is usually part of the treatment as well. Once the swelling of the eyelids has gone down, the turtle is able to see normally again.
Although Vitamin A deficiency often leads to swollen eyelids, this isn't always the case, and you should always ask your vet to consider a bacterial infection as well.
Eye infections will need to be treated with a systemic antibiotic. Because of the close connection between eye infections and living conditions, it is critical to ensure that the turtle's vivarium is optimised. Keep the vivarium draught-free and warm, and ensure that the water is spotlessly clean. Most turtles also need a UV-B lamp for basking.
Avoiding a Vitamin A deficiency is easy enough if a turtle is given an adequate diet. The problem for many hobbyists starting out with turtles is that they assume the dried pellet foods offered by pet stores are an adequate diet; they are not! Before keeping any turtle, carefully research its dietary requirements. Most species of turtle are at least partially herbivorous, and need lots of fresh green foods to do well.
The popular red-ear slider Trachemys scripta elegans feeds very largely on plants throughout its life. Juveniles will need a diet containing about 50% plant material, and adults nearer 75% plant material. Suitable plant foods include dandelion leaves, red leaf lettuce, curly green lettuce and small amounts of green beans, squash and courgette (zucchini). Tomatoes and other fruits can be used as very occasional treats but because of their acidity and high sugar content shouldn't be used too often. The skin and seeds are a potential choking hazard and should be removed before use. Aquarium plant cuttings make excellent staple foods for turtles. Canadian pondweed (Elodea or Anacharis spp.) is cheap, easy to obtain, and can be placed in the vivarium and left for the turtle to graze on through the week.
Vitamin supplements are available but should be used carefully. Always use them within the doses recommended by the manufacturer (or your vet) because overdosing is a distinct possibility. Vitamin supplements aren't strictly necessary if your turtle is eating a healthy diet rich in greens.
To prevent eye infections, always keep the water in the vivarium clean. This means installing a suitable biological filter to remove ammonia from the water, and performing at least 50% water changes every week. Use a test kit to check for ammonia or nitrite in the water; both should register at zero. If you detect either ammonia or nitrite in the water it means that the filter is inadequate to the job and must be upgraded. Ammonia and nitrite irritate the sensitive tissues of the eye, ultimately allowing eye infections to become established.