There are conditions that can cloud the equine eye.
Diseases and Conditions, Eye and Ear Problems, Older Horse Care Concerns, Other Eye Problems were posted by Heather Smith Thomas.
Your horse's eye is very fragile.It is still vulnerable to injury and disease despite being able to endure an amazing number of challenges.A sudden opaque cloudiness over the eye is a sign that something is wrong.
There are a number of things that can cause a cloudy eye.Any horse, from the senior with the scar on his eye due to an old corneal ulcer to the Paint with squamous cell carcinoma, can fall victim to one of these issues.
Some knowledge about the eye's structure can help us understand some of the issues.
The eye's clear outer covering is made up of several layers.The transparent layer of tissue is about 1 millimeter in diameter.You have from the outside in.
The cell composition is similar to a stone wall with fatter cells on the bottom and thinner ones at the top.
A piece of Saran Wrap can be found at the bottom of the layers of cells.
The stroma is made up of long, thin fibers that are organized in layers with a few cells.The body needs cells to repair injury, which is why it is a challenge with so few cells.
Like another piece of Saran Wrap beneath the stroma, the Descemet's membrane is thinner.The cells of the endothelium don't regenerate very well because they hardly reproduce.Like your skin, the epithelium can regenerate completely.A healthy eye will turn over its cells in a week.The density of the cells that make up the endothelium declines with age.If the endothelium gets damaged, the eye is in trouble because they play a critical role in maintaining transparency.
The stroma is relatively dehydrated, so it is transparent.The stroma is pulled out of by thenermost layer of the endothelium.The cornea becomes cloudy if the endothelium is damaged, old, or not functioning properly.
Don't worry if your horse has a cloudy eye.If he shows signs of squinting, tearing, eyelid swelling, and abrupt behavior changes, try to determine if he is comfortable or in pain.You can communicate what you are dealing with by examining the eye in different lighting.
When the horse is outdoors, you can see things in bright sunny light that are not as apparent in a stall or dim light.An associate professor of equine ophthalmology, ACVO is from Germany.When you drive toward the sun at sunrise or sunset, fingerprints or dust on your car's windshield can become more obvious, but disappear when you turn away.
Use a flashlight in the barn to see the cloudiness.If the flashlight is moved around and left to right, you can see the location.
The sooner you can get your doctor involved, the better.If it is nothing, the veterinary examination can confirm that, and you will have peace of mind.Good news is not bad.I would rather see a horse 15 times for nothing than once a week.
The later you start the treatment, the more limited your options are and the less chance of a positive outcome.
Corneal disease can be infectious or immune-mediated and has more long-term consequences.
The conditions most commonly associated with an opaque, cloudy appearance of the eye, not because horses are more prone to these, but because the eyes are open and you can see the cloudiness, areImmune-mediated corneal diseases.An associate professor of equine ophthalmology, ACVO is from Germany.If there is more pain with an eye problem, what you see first is squinting and tearing.
If you notice eye cloudiness, it's a good idea to have your vet come out and diagnose it, as some conditions can be vision-threatening.There are 10 issues that can cause cloudiness.
A puncture wound from a thorn or a blunt force injury could cause fluid swelling and cloudiness.
A more serious underlying problem that can threaten vision can be found in the Edema from blunt force.Treatment for the trauma may include anti-Inflammatory and immune-Suppressive (such as steroid) and systemic medications to control intraocular inflammation.
Surgeries are often needed to repair lacerations or penetrating injuries.If left unattended, penetrating injuries require aggressive antimicrobial therapy to prevent secondary infections, which could result in the eye having to be removed.
Corneal fibrosis is an old scar from an injury or surgery.scarring will result if the damage extended into the stroma.The size of the scar varies with the original insult.The symmetrical geometry that permits transparency may be lost when the repairs don't get laid down with the same type of collagen that nature started out with.There is a blemish on the eye.
If the horse didn't suffer eye damage, these blemishes are usually not painful.This would be like a tiny spot of grease on your glasses.There is a blur but you can see it.
Unless it is very extensive, this doesn't affect the horse's performance.With time, a scar may get smaller.You will end up with what you see after six months to a year.A large scar can shrink down to a small area of fibrosis.
Inform the new owner of your horse's eye history so that they know if the scar is serious.
The focal areas of cloudiness can be caused by tumors such as squamous cell carcinoma.When they start to develop, they are often only recognized as a cloudy or non transparent area of the cornea, but will become larger and have a more visible appearance with time.The first thing you see is a cloudiness in the cornea that indicates something is moving through it.
The surgery to remove the tumor is the most effective way to prevent the regrowth of the tumors.He says the prognosis for preserving vision, maintaining the globe, and achieving a state of nonrecurrence is very good with appropriate therapy in the hands of an experienced ophthalmologist.
There are several types of infections that can lead to opacification.keratomycosis is a disease that presents as superficial opacities in the cornea with a punctate to linear pattern.This almost looks like a little sand on a glass table, with some Saran Wrap placed over the top of it.
The spots push the epithelium up, creating a bumpy look rather than a smooth surface.It would take a lot of magnification in specific lighting to see this.They look like tiny areas of cloudiness to the horse owner.
To evaluate the cells under a microscope, a cytology sample with a cotton swab might be taken.Epithelial cells rub off very easily if you are dealing with an infectious disease.
There is a serious and painful condition called a stromal abscess.Horses with small eyes will hold the eye shut.The hallmark of this condition is a focal opacity, yellow to tan in color and accompanied by pain, intense inflammation, and sometimes blood vessel ingrowth.It is difficult to diagnose most of the time.The vet can't drain it, but it may look like it.
It is difficult and expensive to treat deep stromal abscesses.Severe cases need transplants.
It is not easy to prove that these are abscesses because you can't culture them.Some are not associated with microorganisms.A new technique called confocal microscopy can help sort out the cause of stromal abscesses.
Pioneered by Cornell University's Eric Ledbetter.The method is similar to putting a microscope on a living eye.The examiner puts a light beam very close to the horse's eye and then uses a scanning device to look at the cornea layer by layer.The method enables us to figure out the cause of the abscess very quickly.
A damaged patch of endothelium can allow part or all of the cornea to swell with water and become opaque.We do not have good treatments for it, and we don't understand it very well.The affected section of the cornea looks bluish because watery fluid has come in and disturbed the tissue transparency.We try different things for treatment when we see that bluish area.
She suggests that veterinarians measure the horse's intraocular pressure to rule out the condition.The entire cornea becomes cloudy if the endothelium stops working.
The condition can progress to a point where the fluid in the outer layers of the eye becomes blisters.The bullous keratopathy is a prominent globe where all or most of the cornea is blue in color.The eye can be large or not.Sometimes this goes along with the eye disease.There isn't a good treatment for this.Many of the horses need to be enucleated because they need the eye removed.
A condition in which calcium is laid down is called mineralization of the cornea.
In horses, we may see it in individuals that have ERU, which is inflammation of the uvea, or the cellular layer of an eye that contains blood vessels, the iris, ciliary body, and choroid.It may be related to the fact that many of those horses get a lot of steroid treatment, as it can be a side effect of the steroids.
This is usually found in the upper stroma, the subepithelium, or a combination of those.It is easy to diagnose if you take a sample of the tissue.The little crystals can be seen under the microscope.
This issue is usually manageable, despite being chronic and recurring.It's important to remove as much mineral as possible.The horse can live with it if you can get it to the point where there aren't much differences.
She uses a new procedure called diamond burr debridement, in which she applies a tiny Dremel-tool-like instrument to gently "sand" the ocular surface to remove rough or loose areas.She says that it was developed for humans but has been useful in animals.
She says she applies a 1% preparation of ethylenediaminetetraacetic acid for long-term control.She says that it is well-tolerated by the eye.We put it into the eye twice a day to help control it.
There are deposits on the inside of the eye in older horses.The cornea is no longer able to keep fluid out of it and suddenly becomes cloudy because of those deposits.This is a chronic problem with a sudden presentation.The lower half of the eye is where the triangular areas of edema are found.They can appear at the top of the eye, but it's usually in the lower half.
There are no signs of inflammation in keratopathies.It is possible that these may also present with opacities throughout the cornea.It is common for viral keratopathies or keratitis to be diagnosed.This may be a form of immune-mediated keratitis.
Linear keratopathy is a single line of cloudiness that crosses the cornea.It looks like a tiny railroad track if you look closely.If you only see a single line, it is likely that the eye suffered trauma at one point that caused the Descemet's layer to stretch.If you pull on it from both sides, a piece of Saran Wrap will stretch permanently.
High intraocular pressure is what causes multiple branching lines of cloudiness."If I see a horse with a single line of opaque keratopathy, I don't worry too much, although I keep track of it, photograph it and measure the eye pressure."Glaucoma is almost always accompanied by multiple branching lines.
Immune-mediated keratitis seems to be on the rise.This is a kind of grab-bag condition.We know that it involves cells that govern the immune response in the eye.We see it all the time, but there are no studies or papers on it.Immune-mediated keratitis is a spectrum of conditions that I like to call cloudy windshield.
Sometimes we see horses with little geometric-shaped dots all over the cornea that look like a Chinese checkers gameboard.Some horses have patches of cloudiness.There are a number of patients that I have treated that have a problem with their eyes.The cells that cause the opacity are moving around.
Cells from the immune system are present in the affected corneas.There is a theory that the cells migrate into the stroma as a response to foreign invaders.Some of the horses that show up with these immune-mediated problems have been treated for eye problems before.The original problem may have been a simple one, but we see this immune-mediated problem later on.
Many cases respond to drugs such as cyclosporine.A research team at North Carolina State University has developed a surgical implant that has been used to manage some cases of IMMK.
It's difficult to determine the cause of ocular cloudiness.Some horse owners might hesitate to have the eye checked because it doesn't seem painful, but an exam is much cheaper than aggressive medical or surgical therapy due to progressive damage over time.If your horse is showing signs of a serious eye problem, you should take steps to fix it and preserve his vision.
Heather Smith Thomas and her husband own a ranch near Salmon, Idaho.She has a degree.In history from the University of Puget Sound.She has been raising and training horses for 50 years and has written thousands of articles for horse and livestock publications.Understanding equine Hoof Care, The Horse Conformation Handbook, Care and Management of Horses, and Storey's Guide to Raising Horses are some of her books.She writes a weekly newsletter at http://insidestorey.blogspot.com that comes out on Tuesdays.