| Pigmentary Keratitis is a build up of dark scar tissue
on the surface of the eye. It appears as a brown pigment that may
gradually cover the eye over time, typically starting in the inner
corners of the eye. PK can be caused by numerous things, and can
sometimes be caused by nothing. Most often, this is a symptom of some
other problem, either dry eye, entropion, or ulcers. It can also be
caused by overexposure to the elements. Treatment is the use of
Cyclosporine or Tacrolimus eyedrops given once to three times daily to
try to remove the pigment. Surgery on the eye can help if the scar
tissue is being cause by entropion.
Originally appeared as Ask the Vet by Dr. Shawn Ashley in Pug Talk Magazine (Nov/Dee 91 issue) Pigmentary Keratitis is the response of the cornea to chronic irritation and/or inflammation in which pigment or melanin is deposited in the corneal epithelium (surface of the eye). There are many factors that make this a breed problem in the Pug and other brachycephalic (short-nosed) breeds. Anatomically, Pugs have shortened muzzles which often make for excessive nasal fold skin and shallow eye sockets which cause the eyes to protrude. Protruding eye gives rise to a condition known as lagophthalmos - the inability of the eyelids to fully cover and protect the cornea and distribute the tearfilm effectively. This condition is also one of the underlying causes of prolapsed eyes and dry eye or keratoconjunctivitis (KCS). Other irritating factors include ingrown eyelashes (trichiasis), aberrant eyelid hairs (distichiasis) and not forgetting acute trauma to the eye, as well. The deposition of pigment into the cornea can be permanent if the irritating problem is not resolved - - excessive nasal fold tissue removed, ingrown hairs excised, KCS treated, etc. Once the primary problems have been corrected superficial pigment deposits can often be treated with topical eye medications. If the pigment prove to be deep within the cornea it may be permanent. Surgical removal is recommended only if the area of pigmentation is causing visual impairment. As is the case with many breeds, what makes them unique can also be what causes health problems down the way. The short muzzles and big eyes are what bring the animation into a loveable Pug's face; however, if the nasal fold is too excessive as to rub the eye, the smile can often leave. Nasal fold skin is an inherent trait and can be dealt with over the generations, but if an individual dog is showing related eye problems, seek a veterinarian's counsel; removal of the excess skin may be the recommended treatment. The following article appeared in The American Gazette, December 1990 written by Dr. Steven Timmons, Glendale, Arizona. Every breed is predisposed to certain medical problems, and the Pug is no exception. Perhaps one of the most frustrating conditions is pigmentary keratitis (inflammation of the cornea with the deposition of pigment). The cornea is the clear, window-like structure at the very front of the eye. When we look through this structure from the outside, we see the iris, with an opening at its centre, the pupil. Just past the pupil sits the lens, which is as clear as the cornea unless a problem is present. Since the cornea is the outside covering of the eye, it is susceptible to damage and irritation. Normally the tears form a protective, lubricating and cleansing film which keeps the corneal surface healthy. Irritation of the cornea can result from a variety of causes including decreased production of tears, problems with tear distribution, eyelid hair rubbing on the corneal surface, scratches or injuries from external objects and autoimmune diseases. Pugs tend to react to corneal irritation with more pigment (dark-coloured) deposition. This may be due to the large number of pigment-producing cells around the Pug's eyes. Not only do Pugs produce more pigment as part of their inflammatory reaction, but they also tend to develop inflammation of the cornea at a very high rate. The exact cause of this increased tendency to develop keratitis (inflammation of the cornea) has not been clearly demonstrated, yet there are some obvious structural differences in periocular anatomy that could explain why corneal irritation is so common in Pugs. Perhaps most important is the tendency for entropion of the inferior medial lid margins. In other words, the lower lid tends to curl inward on the side of the eye closed to the nose, allowing hair to constantly rub against the cornea. Most often the irritation and pigmentation of the cornea proceeds from this medial side of the cornea and slowly spreads over the corneal surface. Some Pugs, if left untreated, become pigmented over the entire corneal surface, and, not being able to see through this muddy film, are functionally blind. Another possible problem is excessive protrusion of the eyes, which cannot be swept by the eyelids during blinking, and are therefore not kept lubricated by the tear film. Nasal folds may also touch the cornea and cause irritation. Pigmentary keratitis is much easier to treat if detected early. I recommend that owners examine their dogs' eyes regularly, at least once each week, using a penlight. Shine the light at the surface of each eye from a distance of about three inches. Look for cloudiness or pigmentation on the cornea. Pugs' eyes are so dark that a bright light source is necessary. Without these regular at-home checks, early problems may go undetected, and apparent blindness may be the first thing noticed. By this time, the problem is severe, involving almost the entire cornea. There may also be so much reactive granulation tissue and corneal edema present that a vet will not be able to determine whether the inflammation was caused by an anatomical problem such as entropion, or was the result of an attempt by the eye to heal from an abrasion and corneal ulceration. The owner may believe that his Pug was poked in the eye, when really the disease process was developing for weeks or months as the result of some predisposing factor. Of the utmost consideration in dealing with a Pug's eyes is to act quickly. If a Pug is showing cloudiness of the cornea or irritation to the eyes, or has suffered any form of injury to an eye, immediately seek veterinary care. If an ulceration or severe ocular inflammation is present, time is of the essence in preventing disaster. When pigmentary keratitis is present, tear production should also be checked since keratoconjunctivitis sicea (decreased tear production-induced keratitis) will lead to a secondary pigmentary keratitis. When pigmentary keratitis is the diagnosis, a variety of therapies may be suggested. One is topical cortisone treatment. Since cortisone is inadvisable if an ulcer is present, a vet must be consulted before using any cortisone in the eye. Cortisone is used in pigmentary keratitis to calm the inflammatory response. Antibiotics are often used to control an concurrent infection of the cornea. If keratoconjunctivitis sieca is present, steps must be taken to increase or replace tear production. Pigmentary keratitis can require continued, life-long therapy to prevent further inflammation and pigment deposition. Weekly penlight exams should be continued between vet visits to monitor for recurrence of inflammation. Surgery can be performed to correct entropion or other defects. To correct the medial entropion present, medical canthoplasty may be necessary. This is a more involved surgical procedure than the one used for most entropion corrections. Alternatively, the corneal surface can be excised to remove pigmented tissue, though it may be difficult to control pigment deposition during healing. One bright light on the horizon is the use of eye drops which contain a drug named cyclosporine. There is currently no licensed nor marketed ophthalmic form of this drug, though one is expected soon under the tradename Optimune. Many vets are already preparing and using ophthalmic solutions from the oral solution. Sandimmune, now available for human use (Ophthalmic treatment bytopical administration of cyclosporine is a patented invention [USP 4,649,0471 of the University of Georgia Research Foundation, Inc.) This drug stops the inflammatory process on the corneal surface and in the tear glands. Studies in dogs with keratoconjunctivitis sicea have shown dramatic responses to this drug. Some cases of pigmentary keratitis have also responded, with granulation tissue and corneal edema healing rapidly. The pigmented portions of the cornea may clear from cyclosporine therapy, and clearing of pigment, if it occurs may take months to be noticeable. Perhaps cyclosporine's best use will prove to be in preventing further pigmentation from taking place in Pugs that have a tendency to develop pigmentary keratitis. If you are interested in using this drug, you should consult your vet or veterinary ophthalmologist. Please realize that this drug is experimental and not licensed for use in dogs. Further studies may find that this drug is safe and/or effective form of therapy for pigmentary keratitis. One more thing needs to be addressed. It is probable that some of the factors which predispose a dog to develop pigmentary keratitis are controlled by heredity, even though this has not yet been proven. Nevertheless, we (Pug Breeders), should strive to avoid breeding two affected individuals to each other. After a few generations, we may find that it will be reasonable to breed only unaffected Pugs. I feel we are the caretakers for one of the most fun and friendly breeds. Let us take to heart, just as we take our friend, the Pug, to our hearts, and we will begin the next century with the Pug as a prime example of a breed with a healthy disposition and a healthy constitution. |
Originally appeared as Ask the Vet by Dr. Shawn Ashley in Pug Talk Magazine (Nov/Dee 91 issue)
Pigmentary Keratitis is the response of the cornea to chronic irritation and/or inflammation in which pigment or melanin is deposited in the corneal epithelium (surface of the eye). There are many factors that make this a breed problem in the Pug and other brachycephalic (short-nosed) breeds. Anatomically, Pugs have shortened muzzles which often make for excessive nasal fold skin and shallow eye sockets which cause the eyes to protrude. Protruding eye gives rise to a condition known as lagophthalmos - the inability of the eyelids to fully cover and protect the cornea and distribute the tearfilm effectively. This condition is also one of the underlying causes of prolapsed eyes and dry eye or keratoconjunctivitis (KCS). Other irritating factors include ingrown eyelashes (trichiasis), aberrant eyelid hairs (distichiasis) and not forgetting acute trauma to the eye, as well. The deposition of pigment into the cornea can be permanent if the irritating problem is not resolved - - excessive nasal fold tissue removed, ingrown hairs excised, KCS treated, etc. Once the primary problems have been corrected superficial pigment deposits can often be treated with topical eye medications. If the pigment prove to be deep within the cornea it may be permanent. Surgical removal is recommended only if the area of pigmentation is causing visual impairment.
As is the case with many breeds, what makes them unique can also be what causes health problems down the way. The short muzzles and big eyes are what bring the animation into a loveable Pug's face; however, if the nasal fold is too excessive as to rub the eye, the smile can often leave. Nasal fold skin is an inherent trait and can be dealt with over the generations, but if an individual dog is showing related eye problems, seek a veterinarian's counsel; removal of the excess skin may be the recommended treatment.
The following article appeared in The American Gazette, December 1990 written by Dr. Steven Timmons, Glendale, Arizona.
Every breed is predisposed to certain medical problems, and the Pug is no exception. Perhaps one of the most frustrating conditions is pigmentary keratitis (inflammation of the cornea with the deposition of pigment).
The cornea is the clear, window-like structure at the very front of the eye. When we look through this structure from the outside, we see the iris, with an opening at its centre, the pupil. Just past the pupil sits the lens, which is as clear as the cornea unless a problem is present. Since the cornea is the outside covering of the eye, it is susceptible to damage and irritation. Normally the tears form a protective, lubricating and cleansing film which keeps the corneal surface healthy. Irritation of the cornea can result from a variety of causes including decreased production of tears, problems with tear distribution, eyelid hair rubbing on the corneal surface, scratches or injuries from external objects and autoimmune diseases.
Pugs tend to react to corneal irritation with more pigment (dark-coloured) deposition. This may be due to the large number of pigment-producing cells around the Pug's eyes. Not only do Pugs produce more pigment as part of their inflammatory reaction, but they also tend to develop inflammation of the cornea at a very high rate. The exact cause of this increased tendency to develop keratitis (inflammation of the cornea) has not been clearly demonstrated, yet there are some obvious structural differences in periocular anatomy that could explain why corneal irritation is so common in Pugs.
Perhaps most important is the tendency for entropion of the inferior medial lid margins. In other words, the lower lid tends to curl inward on the side of the eye closed to the nose, allowing hair to constantly rub against the cornea. Most often the irritation and pigmentation of the cornea proceeds from this medial side of the cornea and slowly spreads over the corneal surface. Some Pugs, if left untreated, become pigmented over the entire corneal surface, and, not being able to see through this muddy film, are functionally blind.
Another possible problem is excessive protrusion of the eyes, which cannot be swept by the eyelids during blinking, and are therefore not kept lubricated by the tear film. Nasal folds may also touch the cornea and cause irritation.
Pigmentary keratitis is much easier to treat if detected early. I recommend that owners examine their dogs' eyes regularly, at least once each week, using a penlight. Shine the light at the surface of each eye from a distance of about three inches. Look for cloudiness or pigmentation on the cornea. Pugs' eyes are so dark that a bright light source is necessary. Without these regular at-home checks, early problems may go undetected, and apparent blindness may be the first thing noticed. By this time, the problem is severe, involving almost the entire cornea. There may also be so much reactive granulation tissue and corneal edema present that a vet will not be able to determine whether the inflammation was caused by an anatomical problem such as entropion, or was the result of an attempt by the eye to heal from an abrasion and corneal ulceration. The owner may believe that his Pug was poked in the eye, when really the disease process was developing for weeks or months as the result of some predisposing factor.
Of the utmost consideration in dealing with a Pug's eyes is to act quickly. If a Pug is showing cloudiness of the cornea or irritation to the eyes, or has suffered any form of injury to an eye, immediately seek veterinary care. If an ulceration or severe ocular inflammation is present, time is of the essence in preventing disaster. When pigmentary keratitis is present, tear production should also be checked since keratoconjunctivitis sicea (decreased tear production-induced keratitis) will lead to a secondary pigmentary keratitis.
When pigmentary keratitis is the diagnosis, a variety of therapies may be suggested. One is topical cortisone treatment. Since cortisone is inadvisable if an ulcer is present, a vet must be consulted before using any cortisone in the eye. Cortisone is used in pigmentary keratitis to calm the inflammatory response. Antibiotics are often used to control an concurrent infection of the cornea. If keratoconjunctivitis sieca is present, steps must be taken to increase or replace tear production. Pigmentary keratitis can require continued, life-long therapy to prevent further inflammation and pigment deposition. Weekly penlight exams should be continued between vet visits to monitor for recurrence of inflammation.
Surgery can be performed to correct entropion or other defects. To correct the medial entropion present, medical canthoplasty may be necessary. This is a more involved surgical procedure than the one used for most entropion corrections. Alternatively, the corneal surface can be excised to remove pigmented tissue, though it may be difficult to control pigment deposition during healing.
One bright light on the horizon is the use of eye drops which contain a drug named cyclosporine. There is currently no licensed nor marketed ophthalmic form of this drug, though one is expected soon under the tradename Optimune. Many vets are already preparing and using ophthalmic solutions from the oral solution. Sandimmune, now available for human use (Ophthalmic treatment bytopical administration of cyclosporine is a patented invention [USP 4,649,0471 of the University of Georgia Research Foundation, Inc.) This drug stops the inflammatory process on the corneal surface and in the tear glands. Studies in dogs with keratoconjunctivitis sicea have shown dramatic responses to this drug. Some cases of pigmentary keratitis have also responded, with granulation tissue and corneal edema healing rapidly. The pigmented portions of the cornea may clear from cyclosporine therapy, and clearing of pigment, if it occurs may take months to be noticeable.
Perhaps cyclosporine's best use will prove to be in preventing further pigmentation from taking place in Pugs that have a tendency to develop pigmentary keratitis. If you are interested in using this drug, you should consult your vet or veterinary ophthalmologist. Please realize that this drug is experimental and not licensed for use in dogs. Further studies may find that this drug is safe and/or effective form of therapy for pigmentary keratitis.
One more thing needs to be addressed. It is probable that some of the factors which predispose a dog to develop pigmentary keratitis are controlled by heredity, even though this has not yet been proven. Nevertheless, we (Pug Breeders), should strive to avoid breeding two affected individuals to each other. After a few generations, we may find that it will be reasonable to breed only unaffected Pugs. I feel we are the caretakers for one of the most fun and friendly breeds. Let us take to heart, just as we take our friend, the Pug, to our hearts, and we will begin the next century with the Pug as a prime example of a breed with a healthy disposition and a healthy constitution.