Your pet’s eyes can probably melt your heart, but that isn’t the only special thing about them. Those peepers contain many specialized structures that have to work together. Animal Eye Care of New England provides specialty veterinary care for pets with eye diseases in the Boston, MA area. We treat a wide variety of issues, including disorders involving the cornea, eyelids, tear system, lens, retina, optic nerve, and tissues surrounding the eye. Understanding which part of the eye is affected can make the wide range of veterinary eye conditions much easier to understand.

The types of eye diseases in pets range from surface problems that cause obvious redness or squinting to retinal and optic nerve disorders that may cause vision loss without dramatic external changes. Corneal diseases in pets can affect the clear front surface of the eye, while retinal diseases in pets interfere with light-sensitive tissue at the back of the eye. Lens and eyelid disorders in pets, glaucoma, uveitis, tear-film abnormalities, and orbital disease represent other important categories that a veterinarian or veterinary ophthalmologist may evaluate.

Understanding the Different Parts of Your Pet’s Eye

The eye is more than the round structure you see from the outside. The cornea forms the clear front surface, while the iris controls the size of the pupil and therefore how much light enters the eye. Behind the iris sits the lens, which allows light to pass toward the retina at the back of the eye.

The retina contains specialized photoreceptor cells that convert light into electrical signals. Those signals travel through the optic nerve toward the brain, where visual information is processed. The eyelids, conjunctiva, tear system, and third eyelid help protect and maintain the surface of the eye, while the orbit contains the eyeball along with muscles, nerves, blood vessels, and other supporting structures.

Disease can begin in any of these areas, and one problem can sometimes lead to another. A lens disorder may contribute to inflammation or glaucoma, for example, while an eyelid abnormality can repeatedly irritate the cornea. This interconnected anatomy is one reason a complete veterinary eye examination looks beyond the most obvious visible abnormality.

Corneal Diseases in Pets

The cornea is the transparent dome covering the front of the eye. It helps protect the internal ocular structures and plays an important role in focusing light toward the retina. Because it is exposed to the environment, the cornea is also vulnerable to scratches, foreign material, drying, infection, abnormal eyelid contact, and other forms of injury.

Corneal ulcers are among the conditions that can affect this tissue. An ulcer occurs when the normal corneal surface is damaged, and affected animals may squint, tear, rub at the face, or hold the eye closed. Depending on the cause and depth, an ulcer can range from a relatively superficial defect to a serious wound that threatens the structural integrity of the eye.

Other corneal disorders include inflammatory conditions, dystrophies, degenerations, edema, pigmentation, and species-specific diseases. Cats can develop conditions such as corneal sequestrum and eosinophilic keratitis, while dogs can develop immune-mediated corneal disease such as pannus. The appearance, cause, and appropriate treatment vary considerably, so you’ll need a thorough diagnosis.

Eyelid and Eyelash Disorders

Your pet’s eyelids do much more than close during sleep. Blinking protects the eye, spreads tears across the ocular surface, and helps clear small particles. When the eyelids do not sit or move normally, the cornea may lose some of that protection.

Entropion occurs when part of an eyelid rolls inward, allowing hair-bearing skin to rub against the ocular surface. Other issues animals may have include abnormal eyelashes, eyelid masses, injuries, or an inability to close the eyelids completely, known as lagophthalmos.

These problems can lead to tearing, redness, discharge, squinting, chronic irritation, or corneal ulceration. Some eyelid abnormalities are associated with breed and facial anatomy, while others develop because of injury, nerve dysfunction, inflammation, or another disease. Treatment depends on how significantly the condition interferes with normal protection of the eye.

Tear-Film and Tear-Duct Disorders

Tears are essential to maintaining a healthy ocular surface. The tear film helps lubricate the eye, provides important support to the cornea, and contributes to clearing debris. Tear production and drainage depend on several structures, including glands associated with the eye and the third eyelid as well as the nasolacrimal drainage system.

Keratoconjunctivitis sicca, commonly called dry eye, develops when the ocular surface does not receive an adequate tear film. Dogs with dry eyes may develop thick discharge, redness, irritation, corneal changes, or recurrent discomfort. Some cases require long-term management and monitoring to support the health of the cornea.

Problems can also involve tear drainage rather than tear production. An animal with abnormal drainage may have persistent tearing or staining beneath the eye. Because excessive tearing can also occur when an eye hurts, your veterinarian will need to perform some tests to narrow down the issue.

Uveitis and Inflammatory Eye Disease

The uvea includes vascular structures inside the eye, including the iris, ciliary body, and choroid. Inflammation involving these structures is called uveitis. The condition can cause pain, redness, cloudiness, light sensitivity, pupil changes, or alterations in intraocular pressure.

Uveitis can occur because of disease originating within the eye, but it can also accompany infectious, immune-mediated, traumatic, neoplastic, or systemic disease. Veterinary references recognize that ocular abnormalities can be manifestations of inherited, infectious, degenerative, parasitic, toxic, nutritional, vascular, nervous-system, and cancerous disorders. Disease affecting both eyes may therefore prompt investigation beyond the eyes themselves.

Repeated or severe inflammation can lead to additional complications. Cataracts, glaucoma, adhesions within the eye, retinal problems, and other permanent changes may develop depending on the underlying disease. Controlling inflammation and investigating its cause are both important parts of veterinary management.

Lens Disorders in Pets

The lens is a transparent structure located behind the iris. Its primary role is allowing light and images to pass toward the retina. Diseases of the lens can interfere with transparency or cause the lens to move away from its normal position.

Cataracts are one of the best-known lens disorders. A cataract is an opacity of the lens or its capsule that can interfere with vision depending on its location and extent. Cataracts can be inherited or associated with factors such as inflammation, metabolic disease, trauma, and age, with causes varying among animal species.

Lens luxation and subluxation occur when the lens becomes completely or partially displaced from its normal position. In dogs, lens displacement can be inherited in some breeds or develop secondary to trauma, glaucoma, cataracts, and other ocular changes. An anteriorly displaced lens can contribute to corneal swelling and acute secondary glaucoma, making some lens disorders time-sensitive.

Retinal Diseases in Pets

The retina is light-sensitive tissue at the back of the eye. Because it plays a central role in converting light into signals the brain can interpret, retinal damage can significantly affect vision. Retinal disease may be inherited, inflammatory, degenerative, traumatic, metabolic, or associated with systemic illness.

Progressive retinal atrophy, commonly called PRA, represents a group of inherited retinal degenerative diseases in dogs. Other retinal disorders include retinal dysplasia, inflammation involving the retina and choroid, and retinal detachment. Some conditions cause gradual visual decline, while others can result in sudden changes.

Retinal detachment occurs when the neurosensory retina separates from the underlying tissue. Causes vary among species and can include congenital abnormalities, inflammation, trauma, systemic hypertension, ocular surgery, and tumors. Signs can include dilated or unequal pupils, visual impairment, or bleeding inside the eye, although owners may primarily notice that their companion suddenly cannot navigate normally.

Optic Nerve and Neurological Vision Disorders

Seeing requires more than healthy eyeballs. Once the retina converts light into electrical signals, those signals must travel through the optic nerve and neurological visual pathways to the brain. Disease affecting this pathway can impair vision even when the front of the eye looks clear.

The optic nerve can be affected by inflammation, injury, pressure, developmental abnormalities, and other diseases. Some neurological conditions can also interfere with the brain’s ability to process visual information. This means a pet that appears blind does not necessarily have a problem that can be seen by looking at the cornea, lens, or other external structures.

Glaucoma and Disorders of Eye Pressure

The eye continuously produces and drains fluid, helping maintain appropriate pressure within the globe. Glaucoma develops when intraocular pressure becomes abnormally elevated and damages ocular structures. It can cause substantial pain and irreversible vision loss.

Dogs and other animals can develop primary glaucoma, while secondary glaucoma develops because another disease interferes with normal fluid movement inside the eye. Uveitis, lens disorders, tumors, and other ocular conditions can contribute to secondary glaucoma. This illustrates how one category of eye disease can create complications in another part of the eye.

Tonometry is used to measure intraocular pressure and is one of the routine diagnostic tools used during many ophthalmic examinations. Acute glaucoma requires prompt attention because both comfort and vision can be at risk.

Conjunctival and Third-Eyelid Conditions

The conjunctiva is a thin membrane associated with the eyelids and exposed portions of the eye. Inflammation of this tissue, called conjunctivitis, can cause redness, swelling, tearing, or discharge. However, conjunctivitis describes inflammation rather than identifying one particular cause.

Infection, allergy, irritation, dry eye, trauma, and other ocular disorders can contribute to conjunctival inflammation. This is why a red eye should not automatically be treated as an infection. Corneal disease, glaucoma, and inflammation inside the eye can also produce redness, making examination important when discomfort or persistent symptoms are present.

Animals also have a nictitating membrane, commonly called the third eyelid. This structure helps protect the eye, and an associated gland contributes to the tear film. Disorders involving the third eyelid can affect ocular protection, tear production, or the appearance of the eye.

Orbital Diseases and Conditions Behind the Eye

The orbit is the bony cavity containing the eyeball along with associated muscles, nerves, blood vessels, and other tissues. Disease within this space can push the eye out of its normal position or interfere with comfortable movement. Because the problem may originate behind the eyeball, the eye itself is not always the primary source.

Inflammation or infection within the orbit can cause swelling, protrusion of the third eyelid, bulging of the eye, and pain when the mouth is opened. Foreign material, such as thorns or plant awns, can contribute to orbital inflammation in dogs, and disease can also spread from nearby tissues.

Tumors and other space-occupying lesions can also affect the orbit. An eye that gradually or suddenly changes position deserves veterinary evaluation, particularly when accompanied by pain, swelling, difficulty closing the eyelids, or changes in vision. Imaging and other diagnostic tests may be needed to evaluate structures that cannot be seen during a routine external examination.

Pet Eye Diseases Can Reflect Health Problems Elsewhere

The eyes sometimes provide clues about disease elsewhere in the body. Infectious, metabolic, vascular, neurological, nutritional, immune-mediated, and cancerous diseases can all produce ocular abnormalities. Changes involving both eyes may be especially important when your veterinarian is considering a systemic cause.

High blood pressure is one example because it can contribute to retinal hemorrhage and detachment. Diabetes can be associated with rapid cataract development in dogs. In fact, as many as 80% of pups that are diagnosed with diabetes develop cataracts within the year! 

Infectious or inflammatory diseases can affect structures such as the retina and uvea. The exact relationships vary by species and underlying condition.

How a Veterinary Ophthalmologist Diagnoses Eye Disease

A detailed ophthalmic examination begins with observing the eyes and surrounding structures for symmetry, conformation, and visible abnormalities. The veterinarian can also assess visual and neurological responses before examining individual structures more closely. A darkened room and specialized illumination allow parts of the eye to be evaluated in greater detail.

Common diagnostic tools include the Schirmer tear test for tear production, fluorescein staining to evaluate the corneal surface, and tonometry to measure intraocular pressure. Specialized magnification and ophthalmic instruments can be used to examine the cornea, anterior chamber, lens, retina, and optic nerve. Additional tests may be recommended based on the suspected disease.

Your pet’s history is equally useful. Tell the veterinary team when the change began, whether one or both eyes are affected, whether symptoms are intermittent or constant, and whether vision or behavior has changed. Previous eye disease, medications, trauma, and known medical conditions are also key pieces of info that can help guide the diagnostic process.

CareCredit has a piece on CareCredit problems in dogs. All About Vision also has a good piece on canine eye problems.

Frequently Asked Questions About Pet Eye Diseases

What are some of the most common types of eye diseases in pets?

Pets can develop diseases involving the cornea, conjunctiva, eyelids, tear system, uvea, lens, retina, optic nerve, and orbit. Common examples include corneal ulcers, dry eye, cataracts, glaucoma, uveitis, retinal degeneration, eyelid abnormalities, and conjunctivitis. The frequency of individual conditions varies considerably among species, breeds, ages, and health histories.

Different disorders can produce similar outward signs, including redness, squinting, discharge, cloudiness, or vision changes. Identifying the location and cause of disease is important for choosing appropriate treatment.

What signs can indicate an eye disease in a pet?

Possible signs include squinting, redness, excessive tearing, unusual discharge, cloudiness, swelling, face rubbing, an eye held closed, abnormal pupils, or changes in the position of an eye. Vision problems may cause bumping into objects, hesitation at stairs, difficulty in dim lighting, or reduced confidence in unfamiliar surroundings.

Not every serious eye disorder creates an obvious external change. Retinal, optic nerve, and neurological conditions can affect vision while the front of the eye looks relatively normal. Behavioral evidence of impaired sight therefore deserves veterinary attention even when you cannot see an obvious abnormality.

Are cloudy eyes always caused by cataracts?

No. Cataracts affect the lens, but cloudiness can originate from other structures, including the cornea or tissues inside the eye. Corneal edema, inflammation, glaucoma, and other ocular conditions can create a cloudy appearance. Older animals can also develop lens changes that are different from cataracts.

Your veterinarian can determine where the cloudiness originates by examining the eye with appropriate equipment. This distinction matters because treatment depends on the affected structure and underlying disease. 

Can an eye problem be a sign of another disease?

Yes. Ocular abnormalities can occur with infectious, metabolic, vascular, neurological, immune-mediated, nutritional, inherited, and cancerous diseases. In some animals, an eye examination helps reveal a broader medical problem that was not previously recognized. Disease affecting both eyes can sometimes increase concern about an underlying systemic condition.

When should your pet see a veterinary ophthalmologist?

A veterinary ophthalmologist can help with complicated, recurring, painful, or vision-threatening eye disease, as well as conditions requiring specialized diagnostics or surgery. Cataracts, glaucoma, retinal disease, deep corneal disease, lens displacement, chronic inflammation, unusual eyelid disorders, and unexplained vision loss are examples that may benefit from specialty evaluation.

Sudden blindness, severe pain, significant trauma, a displaced eye, or a rapidly worsening corneal problem should receive prompt veterinary attention. 

Contact a Boston, MA Vet About Pet Eye Diseases

Pet eye diseases can affect everything from the protective eyelids and cornea to the lens, retina, optic nerve, and tissues behind the eye, so that similar-looking symptoms can have very different causes. Animal Eye Care of New England provides specialty veterinary ophthalmology for families in the Boston, MA area who need advanced evaluation of eye disease, vision changes, or recurring ocular concerns. If you have been searching for an eye vet near me, animal ophthalmologist, veterinary eye specialist, or veterinary clinic for an eye concern, contact the clinic to schedule an appointment and learn what may be affecting your companion’s eyes.

This article provides general educational information about veterinary eye conditions and cannot diagnose an individual animal. Consult your veterinarian or veterinary ophthalmologist if your pet develops pain, redness, cloudiness, discharge, injury, or vision changes, and follow the diagnostic and treatment recommendations provided for your individual companion.

Because eye disease can involve many different structures, determining where a problem originates is an important part of diagnosis and treatment. Animal Eye Care of New England serves the greater New England area, including Boston, MA; Providence, RI; and Bridgeport, CT, with specialized veterinary ophthalmology. Our Services page provides a broader overview, while Cornea, Lens, Retina, Glaucoma, and Orbital/Globe cover several major categories of ocular disease.