Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Bulging, Drooping, Distended Eyes in Reptiles

There is nothing more terrifying for a reptile keeper than to see their reptile's eye bulging out or drooping. Fortunately, not all such bulging or distensions are serious. Unfortunately, many are.

©2001 Melissa Kaplan


Eye Basics
The reptile eye is similar in many ways to the mammalian eye. They have a lens, cornea, retina, sclera, vitreous humor. Snakes and some lizards have a spectacle instead of a moving eyelid. Like the skin on moveable eyelids, spectacles shed their top layer during each shed event. The reptile iris contains striated muscles, rather than the smooth muscle found in mammalian eyes; this makes it difficult to impossible to dilate the pupils for in-depth examination of the inner eye structures using drugs typically employed for this purpose. A topical application of a non-depolarizing relaxant can be used in reptiles with moveable eyelids, something your vet is probably already familiar with in examining birds eyes. In spectacled species, injections of curare will be needed.

Lizards and chelonians have a nictitating (third) eyelid, as do crocodiles. These can make examination difficult as this eyelid slides across automatically to protect the eye itself.

Most reptiles have tear ducts (lacrimal canaliculus). Lizards and crocodilians also have nasolacrimal ducts which drain out near the vomeronasal organ (Jacobson's organ). In snakes, the nasolacrimal ducts drain into the vomeronasal organ. The fluid then drains down into the mouth to be swallowed. It has been reported that chelonians do not have a nasolacrimal duct, but there is some evidence to the contrary.

Information on vision can be found in my Reptile Vision article.

There are veterinary ophthalmologists who specialize in diseases of the eye. Since reptiles are not covered extensively in general veterinary classes, it will not be a surprise to find that there are likely very few veterinary ophthalmologists who specialize in reptilian eyes. Thus, when you need need to see your reptile veterinarian for one of the conditions below, do start with your reptile vet. If he or she cannot figure out what is going on, check into seeing if there is a veterinary ophthalmologist in your area with whom you can consult.

Eye Conditions

Droopy Eyes/Bloodhound Eyes
In green iguanas, this is most often a sign of acute or chronic kidney failure. In other reptiles, it may be related the the same or other systemic disorders. In any case, these reptiles need to be seen by a reptile vet as soon as the droop, whether bilateral or on one side only, is seen.

Hypovitaminosis A
This is a disorder that primarily affects chelonians, specifically aquatic species. Fortunately, as proper diet and care information becomes more widespread, the incidence of hypovitaminosis A (deficiency in vitamin A) has decreased. However, hypovitaminosis A has become so associated with swollen eyes that too often turtle keepers (and some vets) just assume that swollen eye = A deficiency and promptly shove vitamin A into the reptile without doing anything to investigate the cause of the swelling. Since the health problems associated with hypervitaminosis A (overdose of vitamin A) are as bad in their own way as too little vitamin A, the poor turtle's pain and health problems are just made worse.

Early on, there is some swelling of the eyelid, some mild welling around the iris, and some tearing of the eye in cases of hypovitaminosis A. In addition, there are changes in the orbital glands. As the condition progresses untreated, the swellings become more pronounced and the conjunctiva becomes visible, swollen and reddened. Reptiles that depend upon sight to feed can no longer see well enough to feed, and so slow starvation sets in, further weakening the reptile.

Along with the necessary correction of the diet and environment, and the administration of vitamin A, the cellular changes in the cells of the eye predispose the already stressed reptile to infection, so the application of a suitable topical antibiotic ointment is recommended. During recovery, artificial tears may also be useful.

Ciprofloxacin and similar opthalmic drops have been recommended over gentamicin drops because of a reported epitheliotoxic (kills epithelial cells) effect of the latter.

The problems caused by parasites rarely cause any swelling or tearing. Mites find the area around the eye of spectacled species to be quite hospitable. The overall problems caused by mites leads to shedding problems, especially of the spectacle (information on how to deal with mites and simple retained spectacles can be found elsewhere at my site.)

Ticks, commonly found on wild-caught reptiles or captive bred ones in direct or indirect contact with wild-caught reptiles, can often be found snugged up near the eye. Various nematodes find the conjunctival sac of lacertid lizards and chelonians compatible with their needs. If you have to ask how to remove them properly, completely, and safely, see your reptile vet.

Puffed-Out Eyelids - Pre-Shed
This is common in many lizards with moveable eyelids, seen most frequently in iguanas and true chameleons. As the skin on the eyelids is undergoing the changes associated with getting ready to shed, the lizard will puff out the eyelids when its eyes are closed. These distensions look frightening from the outside, but they apparently help loosen the old layer of skin, readying it to shed.

Later, once the old skin is ready to break and start coming off, the lizards will often rub their closed eyes against something in their enclosure or area. This might be to soothe an itch associated with the coming shed, or might be done to help gently break the skin so that the final step in the shedding process can begin, that stage where you lizard looks like it has bits of cloth stuck to its eyelids, waving gently in the breeze.

Swollen/Distended Eyeball
In all reptiles, bilateral or unilateral swelling may be associated with an infection inside the eye itself, or behind the eye in or behind the socket; left untreated, it can lead to retinal detachment, blindness or enucleation (removal of the eyeball). Or, it may due to an increase in intraocular pressure, often a sign of infection, injury or some other health problem; left untreated, it can lead to retinal detachment and blindness. Since the cause cannot be determined by the herp keeper, nor are appropriate treatments available over-the-counter, these reptiles need to be seen by a reptile vet.

In chelonians, swollen eyes may also be associated with infected eustachian tubes. Since chelonians fed a proper diet rarely get vitamin A deficiencies, such swellings are rarely resolved by increasing vitamin A orally or by injections. If your vet immediately diagnoses a vitamin A deficiency without doing anything to check for infection, or doesn't appear to be up on proper diet, it would be best to get a second opinion from another reptile vet.

The number of reports in the literature of periocular disease with infectious origin as compared with disease of which an agent could not be isolated may not necessarily reflect the actual incidence of infectious and noninfectious inflammatory disease. David L. Williams, M.A., VetMB

Infections Causing Ocular Changes
There are a variety of organisms that can cause changes in the eye and surrounding structures (lids, glands, ducts). They include:

  • viral infections

  • pox virus (generally identified by the appearance of small, white papules on the skin; may be seen earlier in the palpebral integument)

  • herpesvirus (generally in conjunction with proliferative and ulcerative skin lesions)

  • bacterial infections (Aeromonas, Pseudomonas, Pasturella, Salmonella)

Because of the proximity and interaction of the ocular structures to the mouth and respiratory tract (through the nasolacrimal ducts draining into the mouth, near or through the vomeronasal organ; tearing and exudates from the eyes), early signs of a potentially serious problem may present with both mild swelling and tearing and early signs of respiratory infection.

Other Diseases of the Eye
Other conditions which are not amenable to home diagnosis and treatment are:

  • corneal lesions (caused by forcibly removing a retained spectacle, and by accidental injury to the eye, such as rubbing against a rough branch, improperly concealed nail or screw in the enclosure, or scratched by a claw or tooth)

  • corneal deposits (lipids, often secondary to an underlying eye or general health problem)

  • uveitis (may be related to bacterial infection)

  • hypopyon (may be related to bacterial infection)

  • cataracts (juvenile and senile; post-hibernation) and other vitreous opacities

Other Diseases of the Spectacle
Besides a simply and easily removed retained spectacle, there are a variety of problems that can occur in snakes and spectacled lizards. If the spectacle doesn't come off after trying the techniques in the retained spectacle article, take your reptile to the vet. The cornea is right under the spectacle; using techniques recommended by various books, articles and old-time herp keepers - using an implement to pry the retained spectacle off - can result in severe damage to the eye.

In addition to retained spectacles, drainage problems in the ducts associated with the eye can occur, resulting in fluid buildup, swelling, cysts, and abscesses. Left untreated too long, and the eye may need to be removed. Abscesses in the eye structures may be caused by an infection in the mouth or surrounding areas of the head.

Note that in the case of eye infections caused by any of the above, the eye's involvement is secondary to a more serious underlying systemic infection. This is one of the most important reasons why it is important to not try to treat eye conditions at home: you may well end up wasting valuable time, seriously weakening your reptile, to the point that when veterinary intervention is finally sought, it is too late to save the reptile.

Primary source: Williams, David L. 1996. Ophthalmology. In Reptile Medicine and Surgery, Douglas R. Mader, editor. pp 175-185

Related Articles

Reptile Mites

Reptile Skin Shedding

Reptile Skin Basics

Reptile Vision

Respiratory Infection

Retained Spectacles

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