Ask The Vet: Ophthalmology - March 07

One cataract still allows normal vision in the unaffected eye. If the colt is calm and smart, he will be able to adapt to only using one eye. If both eyes are affected, the loss of total vision is difficult for youngsters. The only drops that can be said to help a cataract, are atropine or other agent to dilate the pupil. These are only helpful if the cataract is in the center of the lens, and there is normal lens around the periphery. The pupil dilates allowing more room for vision around the cataract. As far as drops that dissolve cataracts, there is no scientific evidence that they are effective, but it would surely be great if they were!

A defect on the corneal surface that is raised and white has a high probability of being infected. I would be very careful about discontinuing treatment too soon. It may be wise to remove this tissue and submit it for a second culture to be sure the initial treatment has been effective. It is hard to predict future loss of vision with only a written description!

As long as there is significant corneal pathology or infection, there is the probability of visual deficits later. Often, surgical removal of the corneal defect with a conjunctival flap (a piece of conjunctiva pulled over the defect to assist with healing) is the best treatment for deep corneal infection.

Cataracts are opacitites of the lens, either of the crystalline portion or the thin capsule that surrounds it. They are the most common congenital (present at birth) ocular defect in horses as well as a common cause of acquired vision loss. Cataracts are classified by age of onset, location within the lens and cause (if it can be determined). There are certain terms within these three classifications so that veterinarians may communicate effectively about a given case. I'm not exactly sure what your vet means by "fully formed" cataracts. A diffuse or mature cataract (these appear white) located in the center of the lens, but not extending to the very edges may allow the horse to see around the edges. There are medications that will dilate the pupil and increase the area available for vision around the cataract in some cases. Many cataracts result in a fogginess or blurriness to vision rather than blindness. Sadly, there are no medical therapies to stop, slow or reverse the progression of a cataract. Surgical removal is a viable option if there is no other reason for vision to be lost in the eye. Before undertaking cataract surgery, the ophthalmologist will evaluate the electrical activity of the retina, and conduct an ultrasonographic examination of the anatomy behind the lens to be certain all is normal and that the procedure is likely to result in vision. Cataracts can progress to the point of blindness, but the predictability of this is uncertain. You and your horse have done a lot together it seems. If he were experiencing significant vision loss, you would know. Don't let your worry over something that may never be a problem, prevent your enjoying him further.

Horses do have third eyelids, just like cats. The first thing I would consider in a horse with prolapse of one of the third lids is that perhaps the eyeball itself is smaller than it should be. When the eyeball is not fully in the orbit, the lid is allowed extra room in which to expand. Another cause of prolapse is neurologic disease or damage. This is most often bilateral (involving both), but can be unilateral. It is not likely that EPM is the cause of this. The cranial nerves, important to the action of the third lids, come directly off the brain, while the EPM parasite most often affects the spinal cord. Sometimes, third gland prolapse indicates pain, but if there is no other problem, such as abnormal blinking or sweating, I wouldn't worry.

Behind the third eyelid is a fat pad, which can prolapse past the margin of the lid. It appears the lid is prolapsed, but close examination reveals the lid to be normal. The fat pad or any mass that protrudes can be surgically removed.

My philosophy has always been to remove painful, blind eyes. Even if an eye is blind, if it is nonpainful, leave it alone. The eye will eventually shrink as it dies and become very small, very much like a grape shrinks down to a raisin. If he is not holding it closed, holding his head abnormally, or in other ways making you think it hurts, it probably does not.

The growth may be granulation tissue if it is rough, pink and bleeds easily. If so, it may be wise to remove the growth as it will encourage insects and bacterial infection as it bleeds. If you choose enucleation, it can be done standing, but there are risks both ways (standing and with general anesthesia). Vets have their own preferences. Good luck.

Keratitis is just an inflammation of the cornea and is a rather nonspecific term. Viral keratitis can be more challenging and take longer to resolve than a focal bacterial ulcer. As in other body systems, viral infections often weaken tissue and enable bacterial invaders to gain a foothold. A cornea can appear dull during any disease process, especially those resulting in decreased tear production.

It is also possible for eyes to become sensitive to a particular medication and discontinuing that one can result in rapid improvement. Keep watch on it to be sure things don't get out of hand again.

You need to have your vet out to examine your horse and determine the problem. A simple application of dye to the corneal surface will stain the tears and they will be seen exiting the nasal opening of the tear duct in a couple of minutes if the duct is patent. Conjunctivitis or tear duct infections can also cause this problem and may resolve with systemic and topical antibiotics and anti-inflammatories.

Small cataracts with plenty of room for vision are not a problem for horses. There is nothing you can do short of surgery to help it or stop it's progression. I think as long as UV light has been linked to cataract development in people, there is no reason not to protect our horses with sensitive eyes just in case there is a link!

Thick yellow ocular discharge sounds like an infectious problem. Have you tried an antibiotic/steroid ointment? There may be a conjunctivitis or a growth in the area. It is possible to culture the conjunctival sack looking for bacteria or biopsy the area to see if there are parasites or neopasia. You should continue looking for the cause of the discharge in the hope of solving his problem for good.

The only treatment for a congenital (present since birth) cataract is surgical removal. However, if it is not a complete cataract and there is some normal lens visible around it, there is the possibility that as the foal ages and the lens grows, the cataract may be compressed into the center of the lens and there may be some vision around the edges. Eye drops will not work.

He had been doing something silly to himself it sound like. It is more common than you might think. I have had two clients in the past several months with horses that had recurring eye problems. One horse we changed location of the feeder and the other changed to a paddock without branches, and no further problems. I would reconstruct the lid margin though. It is important to have a normal lid margin to control tears and protect the delicate cornea. If the defect is significant, it should be fixed, if minor, I'd just keep watch for any problems.

It is likely he has developed a fistula or draining tract from the nasolacrimal duct to the outside. The duct may have been damaged by a foreign body and developed this tract. If he has a normal nasolacrimal duct with this small addition, I wouldn't worry a bit, but you will have to wipe his face with a thin coating of vaseline to prevent the fluid from scalding his skin and causing the fur to fall out.

Eye problems can be challenging. They can get bad very quickly, and some heal very slowly. It is always best to treat eye problems as an emergency and have a complete evaluation as quickly as possible. If there is the possibility that a sliver came out of your mare's conjunctive or near the eye, there is the potential for an abscess or infection developing. I would ask your vet for a referral to someone with an interest in ophthalmology.

You describe your pony as having a baldface, so I take it that there is other coloring on her body. If so, she does not have an absolute lack of pigment in her skin. The most extreme case of lack of pigment in the skin is called an albino. These have no pigment, there fur is white and their skin is pink. Their irises are either very pale or pink. The color of the iris is a function of it's thickness rather than the presence of true pigment.

I want to give you some anatomic background before I answer your question, so bear with me on this! The fundus is the back of the eye and in a horse, it is divided horizontally into the upper tapetal area and lower nontapetal area. The tapetum is the reflective layer that causes the "eye-shine" you see at night when you shine a flashlight in the pasture. When observed through an ophthalmoscope, this layer is iridescent blue, green, gold or yellow depending on the coat color of the individual. The purpose of this layer is to improve vision in dim lit conditions by allowing gathered visible light to stimulate the extra chemical light receptors found there, but the price of this ability is increased glare and decreased visual acuity in bright light. Most pale-eyed horses with pink-skinned faces have some decrease in their tapetal area if not a complete lack of it. Color-dilute animals such as albinos, cremelos, silver dapples and even merled dogs, also have little or no tapetal area. This is referred to as a non-tapetal or non-pigmented fundus. These eyes, while more sensitive to sunlight and more likely to suffer from certain skin cancers around the eye, do not generally have visual deficits. Color dilute animals are more likely to have various syndromes of ocular defects, which may have a component that affects vision. If your pony is not a color-dilute animal, and is not showing visual problems, I would train her and have fun with her. I think the mask is a good idea if it is one that affords UV protection.

Astigmatism is an abnormal curvature to the refractive surfaces of the eye and most often referrs to corneal curvature. Normally, the cornea refocuses light as it passes through causing the beams to be delivered to one point on the retina, therby allowing the visual image to be formed. Astigmatism can be secondary to trauma or severe corneal disease, which results in an alteration of the shape of the cornea. By the time the abnormal curvature has progressed to the point of causing a good natured and calm horse to begin acting goofy, it is usually not difficult to diagnose by magnification. If the cornea appears undamaged, I would look further for the cause of his problem. Many times, causes of visual deficits in horses are found in the posterior segment (back of the eye). There may be lesions of the optic nerve or choroid. The choroid is the layer behind the eye that often contains evidence of prior infectious or inflammatory disease and these, if numerous or large enough, can affect vision.

If he has recurrent uveitis, it is not unusual for the flare ups to be far apart. Consider yourself to be lucky, often as time passes, the flares occur with more frequency. The best thing you can do is be diligent about examining his eyes daily and being quick to consult your vet at the first sign of a problem. If you travel with him regularly to shows, be sure to pack a kit with you in case of a problem away from home. You should have bute and an eye ointment so no time is wasted.

Many growths found on the conjunctiva or lid margin have the potential to be cancerous. Squamous cell carcinoma is the most common type found, and these lesions usually begin as small ulcerated or red areas on the tissue before they actually begin to grow in size. If this is a horse with pink lid margins, he is at higher risk for it being cancerous. Surgical removal is your best option. This allows not only a treatment of the problem, but a definitive diagnosis by sending it to the lab. Many squamous cell lesions have rather deep roots so the biopsy will be able to identify if the entire tumor has been removed. Many veterinarians, myself included, often follow-up surgical removal with an injectible form of chemotherapy to try and guard against further growths. No, a specialist is not required for this one!

Primary retinal tumors are very rare and are usually secondary manifestations of tumors elsewhere in the eye or nearby ocular structures. Metastatic masses of the retina or choroid are sometimes incidental findings from primary non-occular tumors. If it is small and there is no evidence of neurological or visual deficits on examination, I would suggest routine rechecks every 6 months to evaluate it's growth.

As long as the fungus has completely cleared and has not reoccured once the medications have been discontinued, I would look to other reasons for the weepy eyes including blockage of the tear ducts or pain from another source, i.e. corneal ulcer or uveitis. Having said this, I would be sure to fully evaluate the eye for a recrudescence of the fungus. Fungal infections are notorious for hanging around longer than expected, and for appearing to be controlled only to reappear when medications are discontinued. If you have not already reported this to your ophthalmologist, please do so immediately.

Some white horses with nonpigmented (pink) eyelids are prone to sunburn. Just like people, some are more sensitive to the effects of a burn than others. Often a sunburn on the pink tissue around an eye will cause inflammation and swelling in that area. This swelling can cause the nasolacrimal ducts to become occluded leading to tearing. The tearing, in such cases, is a combination of the inflamed eyes tearing more as well as the occluded duct not allowing the tear volume to drain. Often these animals will lose the hair around the corner of the eye where the tears flow. If this is the case, you are doing the right thing by having him wear a good mask. I have also had luck with waterproof sunblock applied daily. Bullfrog is the brand name of one that seems not to sweat or melt away as fast as most. If he also sunburns on his nose, there is an excellent mask on the market with a flap that falls over the end of the nose to afford more protection.

When you add the inflammation of the conjunctiva to the tearing it becomes a conjunctivitis. This is the common 'pink-eye' you hear about. It may result from one of several causes: bacterial infection, parasitic granuloma, allergic reaction. As long as there is no evidence of a corneal ulcer or other surface defect, often an antibiotic ointment combined with a steroid is helpful in relieving the signs of conjunctivitis from bacterial or allergic causes. If it is a parasitic cause, the granuloma can be removed, and a medication for killing any remaining parasites can be accompanied by an anti-inflammatory for the swelling and discomfort.

The incision over the empty socket should be treated much like any surgical wound. Depending on the surgeon's preference, he may have told you to gently cleanse it daily with warm water or a mild antibacterial wash. Once the sutures are out and the incision healed, there is no need to give the area any special treatment. Believe me, it bothers you much more than it bothers your horse! I hope he is adjusting to having one eye. Many horses have no problems after the first week or two, and are very smart about paying attention and turning their heads towards the blind eye to be able to see with the opposite. We people just need to remember to be more aware of letting these horses know where we are when near them, and be careful that if we don't startle them so their big heads don't smack us as they turn to get a better look!

The blue haze to the eye's surface is edema, which is fluid between cells, or in places it shouldn't normally be found. Often eyes with this kind of diffuse edema have uveitis, an inflammatory condition that often reoccurs, but can usually be managed. The second reason for equine eyes to become diffusely edematous is glaucoma. This is a condition caused by an increase in intraocular pressure resulting either from an increase in the production of fluid or a decrease in the release of the fluid from the eye. This is more difficult to control. The appearance of these two causes of diffuse edema are slightly different, but the determination is important for proper therapy. If one eye has progressed to the point of blindness and complete edema, it is likely not a bilateral (affecting both sides) condition.

Anterior segment dysgenesis (ASD) is a genetic condition resulting in the abnormal embryonic development of certain inner eye structures. There is no treatment since it is an abnormal development. There are really several syndromes based on their clinical presentation and several do not affect vision, they are merely an imperfection of structure. The only component of the syndrome that can be treated is cataracts, and these can be surgically removed. The syndrome is closely linked with the silver dapple gene and has been found primarily in Rocky Mountain horses, although also in Tennessee Walking horses and other breeds with a silver dapple gene.

Blunt trauma to the eyeball can be a very serious injury. Most of the inner components are suspended in liquid or gel by very delicate structures. The worse case scenario is that the eye can rupture from the force of a hit. Other possible consequences include retinal detachment, lens luxation and displacement, and superficial damage such as bruising or lacerations. The shockwaves of the blow can result in bleeding into the eye as well as leaking of fluid. Obvious treatment choices involve anti-inflammatories, cold compresses to reduce swelling and further treatment specific to the injury sustained.

Eye disease does tend to progress and if this has been going on for three years, there may be several sequelae to the initial problem present. Many forms of eye disease are reversible if treatment is sought within a reasonable time.

It is often difficult for owners to decide where the source of eye 'cloudiness' really is. The cornea can be affected and this can indicate an ulcer, uveitis or glaucoma. The lens can be affected and this is often a cataract. In some cases, the fluid within the eye becomes thick with inflammatory cells and protein. Thick ocular discharge often indicates infectious disease. Without a picture, it is difficult to narrow down your options. I do think you should have a veterinarian with an interest in ophthalmology evaluate her for you.

What appears to be cloudiness in pupils may actually be a cloudy lens that you see through the pupil. Opacities of the lens are called cataracts and they are common in older horses. There is a decrease in vision as the lens becomes less optically clear and allows the passage of less light. The only correction for cataracts is surgical removal.

Allergic reactions that present with ocular symptoms tend to affect both eyes. I would be concerned that there may be an infiltration of abnormal cells (neoplastic/cancerous). Grey horses are prone to such problems. Curiously, they can sometimes seem to come and go. It may also be an infection in the soft tissues of the lid that will respond well to antimicrobials. You may consider asking your vet for a referral to an ophthalmologist.

Opacities on the cornea can be one of the signs of uveitis. Herpes causes a certain type of ulcers found on the cornea. Herpes ulcers have an unusual punctate appearance, which makes them easy to identify on a simple examination. Ulcers affect the corneal surface while uveitis begins deeper in the eye, in the structures responsible for circulation of fluid. The two diseases are different and their treatments are different. If his cornea is clear now, I would suggest only that you remain vigilant in your observation and seek a veterinary exam if they do seem to reoccur. The benefits of Lysine in affecting ocular disease are questionable, and the proper dose for any effect is also unknown.

A ptergium is a superficial and benign growth of conjunctival tissue spreading onto the cornea. It is the result of irritation (light, dust, abrasion, poorly places harness or bridle straps...). If large enough to affect vision, they can be easily removed. There is no other treatment, although I have had some decrease in size after topical steroid application. Eyes drain as a result of irritation as well. Ptergia can have the appearance of cancerous growths and especially resemble squamous cell carcinoma, the most common type of cancerous growth found on the eye's surface. Surgical removal would enable a diagnosis to be made.

Nuclear cataracts are those in the center of the lens. Consider the lens to be like a jelly doughnut sitting on its edge. A nuclear cataract would be where the jelly is. A posterior cataract would be on the back (posterior), behind where the jelly would be. A cataract is classified by location, so it is either nuclear or posterior. They are also classified by size, hence the 8mm measurement. The stippled appearance means it looks like tiny pin pricks on the surface. Sometimes strands of iris adhere to a lens, but not so in your horse. He has described the eye in great detail for you. The menace and pupilary light response are tests to evaluate vision and normal neurologic functioning. The PLR is a pupil decreasing in size when bright light is applied. Sunlight is a contributing factor to cataract development in people, so I would have a UV protective mask on her when out in the light just in case. There are surgical options for cataract removal in horses that you may want to consider.

It is not uncommon for a cornea to retain a grey area where a deep or severe ulcer once developed. The cornea is transparent because of the perfect architecture of it's cellular arrangement, so any disruption to this will result it a visible change. It will go away, although expect it to take a long time to resolve. As long as the eye is nonpainful, I wouldn't worry. As far as vision, I suspect it is much like us having a smudge on our sunglasses. You can see through it, but it is a bit blurry.

Uveitis is a condition caused by the immune system's abnormal response to some infection or in some cases, inflammation. It is a sequela to an inciting disease. You can test for antibodies to various diseases, which may have been the cause. However, in some cases, the uveitis follows clinical disease by months or years. The diagnosis of uveitis is not difficult in an affected eye, but there are many reasons for ocular drainage. If the drainage is not associated with pain (noted by squinting) it is often a blocked tear duct or eyelid problem. If the tearing is associated with pain, there may be an ulcer or foreign body, or it may indicate pain from within the eye (uveitis, glaucoma, etc.).

Any horse with a lot of swelling in the medial canthus area should be evaluated for parasitic granulomas. If this area of her eye is nonpigmented, i.e. pink, she would also be at high risk for neoplastic disease. The opening to the nasolacrimal duct may be blocked at the medial canthus. If the owner is spending money to breed his mare, he should be willing to spend some to insure her health. An examination may be all it takes to obtain a diagnosis. Be careful of the "horse with lepto" trap. Just because a horse has some serum titer to Lepto does not at all mean the animal has this disease.

I would consider other causes of pain in this horse. Severe ocular pain is usually such that horses are protective of their heads and not banging them into walls. I would immediately make an appointment with an internist to rule out neurologic issues as well as ophthalmic ones.

A floater is usually a small bit of protein or cells trapped in the aqueous or vitreous - the fluid in either the front or the back of the eye.
Many people have them also and while they float through your field of vision, they are not harmful. Of course 'floater' is a nonspecific term, so I'm assuming the colloquial definition!

Corneal ulcers are defects in the epithelium (the topmost layer) of the cornea. If there was no infectous organism such as virus, bacteria, or fungi, one could consider structural defects of the cornea as could be found with an irritant, cellular or crystal accumulation, or neoplasia. Tear film defects have recently been studied as another cause of nonhealing ulcers. Speculation on chances of recurrence and heritability would require a diagnosis, which you don't have at this time.

It sounds like something itches or pains him in that area. You might consider having a skin scrape conducted to check for parasites and maybe a skin culture to see if there is a fungal infection. Both of these can be very itchy! Is there redness to the conjunctiva? That is the pink tissue that surrounds the eye and is under the lids, upper and lower. Often, conjunctivitis is itchy as well. If he has suffered insect bites or abrasions around the eyes, these could lead to a soft tissue infection called cellulitis, which can itch and feel uncomfortable. All of these possibilities can be treated once properly diagnosed, so I would encourage you to call your equine veterinarian.

Often in horses, uveitis is bilateral; or if unilateral, eventually develops in the opposite eye. You are doing the right thing having him evaluated by an ophthalmologist on a routine basis. I'm sure you are careful to keep watch for any early signs of uveitis such as tearing, holding the lids partly closed, haziness or blueness to the cornea. As far as prevention, I would keep a face mask on him when not being ridden to provide some shade from bright sunlight, which can cause inflammation in imperfect eyes.

You're right, the vaccine could have caused the uveitis. As far as the other eye is concerned, I would be very watchful of it. A low dose of aspirin has been helpful in preventing flair-ups of recurrent uveitis. Often the early signs of active disease are cloudiness to the cornea, or sensitivity to light. He may hold his lids partly closed, and his eye may be tearing. You might notice a yellow haze to the fluids in the eye, which indicates the presence of protein or cells accumulating there. Adequan injections have been used for its beneficial effects on uveitis as well, and it may help prevent a flair. An injection a month would be a good start if the eye is quiet. Since your boy only has one eye remaining, it may be worth the expense. As far as the nutritional supplements are concerned, there is no research to indicate their benefit. I certainly wish you luck with him.

The pupil of the eye is the hole formed by the surrounding iris tissue, so it will not have a tear in it. There is no way to tear the iris without a penetrating wound or the rupture of a cyst. If you need to protect a horse's eye from bright light, there are many UV-protective masks on the market that are effective.

Maybe instead of a torn pupil, you mean a torn corpora nigrans. These are the dark bubble-like projections from the edge of the iris. They can tear free and sort of dangle into the pupillary opening. It may effect vision like something blowing into your face would, but are generally considered to not be a problem.

It sounds like he is a good sport to take all his meds for you! It is important to try and define the underlying cause of glaucoma and treat that, rather than just treat the glaucoma. Often this is not possible though. Treatment centers around decreasing the inflammation and decreasing the production of the aqueous fluid within the eye. There are not that many options for this therapy, so medication is not too intensive. If the horse fails medical treatment there are surgical options, but only after active inflammation has been controlled. The East coast is pretty long, but NC State has a well-respected department as far as equine ophthalmology is concerned.

Although there is no scientific evidence to indicate the antivirals are active against the EHV-2 virus, which causes viral corneal disease in the horse, we often use them in case they are of some benefit. These drugs are only virostatic, meaning they prevent the growth of the virus, but do not cause its death. For this reason, their use is recommended 4 to 6 times daily during active disease. If the ulcers are taking up stain, we often add a topical antibiotic ointment as protection against bacterial invasion. There are also new topical anti-inflammatories, which are also recommended. A decrease in stress may help prevent recurrences. Can you associate any stress event with the flare-ups he suffered in the past?

What you describe is the normal progression of an essentially dead eye. It literally shrinks, much like a raisin in the orbit as there is no longer fluid being produced in it. Many blind eyes are enucleated (surgically removed) because they are painful. Your mare is fortunate that her blind eye is nonpainful. Eventually, it will shrink to the point that it will be too small to make her open her lids, but it will always have a remnant present. It can still be enucleated to present a more cosmetic appearance for you though. It is important to keep it clean like you are doing as protection from insects. These eyes rarely become infected and rarely cause any problem at all.

That is a tricky question! Some horses develop a low level of uveitis and are left undiagnosed and untreated. Evidence of the disease is discovered on a routine exam. Other horses suffer a severe acute attack and despite correct and aggressive therapy, are blind in a matter of weeks. Other causes of rapid blindness are severe corneal disease such as a fungal infection, or trauma resulting in retinal detachment. Blindness can also occur from an infection of the optic nerve as may be found in certain cases of West Nile virus, or tumors of the optic nerve or retinal tissues.

Cataracts are often the result of inflammatory eye disease in horses. Your old fellow may actually have nuclear sclerosis, which is considered a normal age-related change in the lens. It appears very much like a cataract, but the retina is still visible through it and it has little effect on vision. There are good eyemasks on the market that offer some protection from ultraviolet radiation. Most horse supply catalogs have them in stock.

Having the lenses removed or cataracts removed from within the lens capsule is the treatment for cataracts. There would be no other reason for this procedure to have been performed. Juvenile cataracts are those occuring in foals or young horses and they are not always congenital, meaning present since birth. Not all congenital defects have proven to be heritable, i.e. inherited from a parent. Some defects are just an error in development. Some cataracts are inherited, but not all, and the jury is still out on the probability of inheriting this defect, but it is not that high or the determination would have been made already! The cataracts found in youngsters are the best ones to have surgically removed. There should not be any health concerns following this surgery if all is well several months after surgery.

Personally, I would not worry about breeding this horse assuming there was something to recommend it's contributing to the equine gene pool. If however, there was even one foal born with cataracts, I would worry about future problems.

I wouldn't worry about a blue area on an iris, it is just a change in thickness at that location. If the entire iris has recently changed color, that could indicate infection within the eye. If the lower lid defect has a flap or a large separation, it may affect her vision if she sees the movement or sees a shadow when she blinks.

There could definitely be differences in her vision. It is possible to have areas of cloudiness on a lens from a previous infection, or even a cataract. The retina itself can have lesions on it leaving a blind spot. These lesions can range from multiple small spots to a single large spot. There are certain measurements and numbers of defects that are accepted to result in visual deficits. Keep in mind too, some horses are just one-sided and are silly in one direction! Horses eyes are set to the side to give them greater peripheral vision at the cost of good depth perception and direct forward vision. Eyes set to the front will have better ability to evaluate distances correctly, although I doubt subtle changes in eye position will make a statistical difference among members of the same species.

This is a vague question, but in general, white things attached to the cornea are often growths or scars. The size would make a difference, as well as how high it is from the surface. You should have her checked out to be sure it is nothing serious.

An eye that is being held partially open is painful. Just because a cause was not identified at the first examination does not mean there was not a cause to be found. Pain does not come only from the cornea, the surface of the eye. Pain can also come from internal structures that must be carefully evaluated. Definitely make an appointment for another examination. If your vet still sees nothing to account for the signs your horse is showing you, perhaps he can suggest a referral for you.

Since uveitis is an immune system disease, you would logically think there could be occurrences with allergic disease, since it is all about excessive immune stimulation. I am unaware of any research that definitively indicates this to be, but that does not mean it is not. Leptospirosis has definitively been associated with cases of equine recurrent uveitis. The importance of positive serum titers has been hotly debated for years. The point of contention is that many horses have been exposed to Lepto and therfore have positive serum titers and most of these animals have no eye disease. When they look at titers in the eye fluid, positives tend to be associated with uveitis and negatives do not. It can take years from a positive serum titer to acquire a positive aqueous (eye fluid) titer. Simply put, a positive aqueous titer is of more significance than a positive blood titer.

If the nasolacrimal ducts have proven to be blocked when flushed, instilling some steroid and antibiotic in them may help. A more broad-spectrum antibiotic choice may be helpful. He may have early cancerous changes, parasitic disease or be sensitive to bright light. You might try a UV-protective face mask.

Paints with pink lids can be problematic. Have a veterinarian examine his eyes to be sure there is no evidence of neoplasia (cancer) or infections. There are also some parasites that can cause chronic eye irritation. It is unusual for horses to suffer from conditions causing 'dry eyes'. He may have allergic issues or blocked nasolacrimal ducts. Eyes with nonpigmented lids are often more sensitive to sunburn and an eye mask is often helpful. You can also tattoo the lid margins, or apply a waterproof sunblock to the area beneath the lower lids. There is a really nice mask on the market that covers ears, face, and also has a flap that covers the muzzle on pink-nosed ponies!

If the nasolacrimal ducts have proven to be blocked when flushed, instilling some steroid and antibiotic in them may help. In my hands, Terramycin is not great for equine eyes. A more broad-spectrum antibiotic choice may be more helpful. She may have early cancerous changes, parasitic disease or be sensitive to bright light. You might try a UV-protective face mask.

Ultraviolet light is divided several different ways based on wave length. The division most people are probably familiar with is UV-A, from 400-320 nanometers and UV-B, from 320 to 280 nanometers. The UV-B waves are the ones considered to be most harmful to the eye and your lamp is not emitting these. Ultraviolet light is invisible to human (and equine) eyes, but visible to many insects, hence it's use as an insect trap. I have known many clients with them, and have not come across any problems. I have also been unable to find any references to horses becoming fixated on these lights. Therefore, this should not be a concern.

This time of year I see a lot of teary-eyed horses. As long as there is no evidence of corneal disease, or other cause, it is usually helpful to flush the nasolacrimal (tear) ducts. Tear ducts can become blocked by dust or swollen from inflammation such as may be caused by allergies. If you suffer from hay fever, you get the idea! The procedure is simple, and most horses do not even require sedation. A small tube is threaded several inches into the opening of the tear duct located in the nostril. About 20cc of sterile saline is slowly flushed through, with the potential addition of antibiotics or anti-inflammatories. The other opening of this duct is located in the corner of the eye. When the system functions normally, tears flow from the eye down the duct and out the nostril opening.

You are smart to keep her face clean. Insects drink tears and leave behind parasites and bacteria.

Rockies are one of the breeds affected by a heritable condition called anterior segment dysgenesis (ASD). This syndrome is an abnormal growth of certain structures within the eye. It is heritable, meaning passed by the parents, and it is congenital, meaning present at birth. Some of the abnormalities may not be able to be detected at birth, although they are present. This syndrome is relatively new and attempts are still being made at research centers to accurately describe its development. It is known to be highly associated with the silver dapple gene. Common abnormal components of this syndrome include corneal curvature, filtration angle, iris and corneal-scleral junctions. Although cataracts are technically not a part of this syndrome, they are not uncommon in affected Rockies. The speed of cataract development is variable. Some cataract types are slowly progressive and some are rapid. Juvenile cataracts are not uncommon in horses, but you did not give your horse's age. I am not familiar with the lineage of the breed, but the breed association does require a breed survey of this eye condition before an animal is approved for breeding and they should be able to find that data.

One of the few things you can do to protect horses against eye disease is provide a shield from ultraviolet radiation, especially if your horse has depigmented skin around the eyes. There are good face masks available with UV protection. Potential causes of uveitis include any infectious disease, and many noninfectious causes. It is an immune-mediated syndrome, meaning the result of an overwhelmingly aggressive immune response. It's occurrence and pathophysiology is still under investigation, even so it is estimated that about only 2% of American horses have vision-threatening disease. Other than basic care, there is nothing you can do to prevent it's occurrence besides, as you already mentioned, consulting your veterinarian at the first sign of an abnormal eye.

Obviously, it all depends on what the "drops" are. There are therapeutic drops that do help some cases of equine glaucoma. Some blind eyes are nonpainful and some are painful. Of the painful ones, options are to enucleate or inject the eye causing it to die, resulting in a nonpainful situation.

Sarcoids are the most common tumors in horses. Although not malignant, they are often invasive and recurrent. There are several different types classified on appearance, so they are difficult to diagnose without microscopic evaluation of the cells. For this reason, a surgical biopsy is suggested for a definitive diagnosis. Surgical removal alone is not often curative. Half will
recur within one year. Surgical removal, followed by freezing, burning, radiation or chemotherapy has a better cure rate. The best cure rate is obtained with implanted radiation beads, which can only be accomplished at specialty centers. Various injectible chemotherapeutic compounds are available as well. All of these treatments have variable success rates depending on the tumor type, size, chronicity and location. Tissue around the eye is not as forgiving as that on other locations, and any sarcoid treatment that allows tumor regrowth often results in a faster-growing and more aggressive tumor. I would strongly suggest that you invest in an examination by a veterinary ophthalmologist for discussion of the many treatment options available. As with any other medical condition, if there are many, many treatment options, the odds are that none are greatly effective.

A common endpoint to uveitis in horses is blindness often from cataracts or severe corneal damage, and often this is after chronic changes have occured that render the eyes nonpainful. If this is the cause of her blindness, yes, you should be thankful. Many blind painful eyes are removed or injected to result in nonpainful eyes (or lack thereof). I hope she is doing well for you. Many horses become very fearful and a danger to themselves and their handlers once their sight is lost.

Uveitis is most often recurrent in horses, i.e. the result of inflammatory changes in the eye and not from a single traumatic episode. To me, that means treat the initial occurrence aggressively, but be very watchful for signs of recurrence. I don't put a horse on a lifetime
treatment until a disease proves itself to be recurrent.

Because the inflammatory changes that cause equine recurrent uveitis (ERU) are secondary to a systemic infectious response, this disease is usually bilateral - affecting both eyes. If a flair-up is noted in one eye, always treat both. Just because we can't see the inflammation does not mean none exists at a chemical/molecular level. All inflammation starts before we can appreciate external evidence of it's presence. Aspirin is often used as a long-term anti-inflammatory medication between flair-ups for this reason. Once there is a flair-up, more aggressive systemic and topical medications are used.

It has become more common for many of us to use a low dose regimen, 30mg/kg once daily or even every other day. This helps decrease the potential for gastrointestinal ulceration while still being effective. While it is true that willow bark contains a chemical that is converted by the body into salicylic acid, which is extremely close to being aspirin, it is not classified as a drug. Therefore, it's formulation and concentration has not been regulated and proven. If you show under an organization into drug testing, many herbal supplements contain forbidden substances that can get you into trouble.

I would be concerned about the occurence of squamous cell carcinoma (skin cancer) on an albino eye. By 'albino eye' I am assuming you mean a pale iris and nonpigmented lids. These are the most likely eyes to be affected. Many times this condition begins with matter accumulation, redness of the lids and sclera and what appears to be an ulcer on the lid margin. Masses as you describe, are not as common, but can occur. You need to have her evaluated by a veterinarian with an interest in ophthalmology. If your vet feels cancer is a possibility, the growth will be removed and submitted to the lab for a definitive determination. Horses with pale eyes and pink lids should wear masks to protect them from sunlight, or go to night turnout. Another possibility is having the lids tattooed.

You are doing the right thing by daily washing around her eyes. Insects love to drink tears and their little feet are full of bacteria!