Superficial Punctate Keratitis (SPK) describes damage to the cornea, the clear, protective outer layer of the eye. It is not a disease itself, but a clinical sign of an underlying problem causing irritation or injury. The condition is characterized by the death of small groups of cells on the corneal surface, creating tiny, scattered lesions that resemble minor scrapes.
Symptoms of Corneal Irritation
The damage to the corneal surface that defines SPK often leads to a distinct set of uncomfortable symptoms. Many individuals report a persistent foreign body sensation, which feels as though sand or grit is trapped in the eye. This is frequently accompanied by photophobia, a sensitivity to bright light that can make normal lighting conditions feel painful. The eyes may also appear red and produce an excessive amount of tears, a condition known as epiphora.
These symptoms can also affect vision. Some people experience vision that is slightly blurred or seems to fluctuate throughout the day. The level of discomfort can range from a mild, gritty feeling to significant pain.
Underlying Causes of SPK
A wide variety of factors can lead to the corneal cell damage seen in SPK. It is a nonspecific finding, meaning it can be linked to numerous underlying conditions ranging from environmental exposure to infection. The specific pattern and location of the corneal damage can often provide clues to the root cause.
One of the most frequent causes is Dry Eye Syndrome. The tear film lubricates and protects the cornea; when it is unstable or insufficient, the corneal surface becomes vulnerable to damage from air and the blinking of the eyelids. This instability leads to the development of SPK, a common finding in people with dry eyes.
Contact lens wear is another major contributor. Problems can arise from wearing lenses for too long, inadequate cleaning routines, a poor fit, or a sensitivity reaction to the lens material or cleaning solutions. These issues can deprive the cornea of oxygen and introduce debris or pathogens, leading to inflammation and cell damage. Bacterial keratitis caused by Pseudomonas aeruginosa is often associated with contact lens use.
Infections are also a direct cause of SPK. Viral conjunctivitis, most commonly from an adenovirus, can lead to an inflammatory response that affects the cornea. Bacterial infections, such as those from Staphylococcus aureus in cases of blepharitis (eyelid inflammation), can also injure the cornea.
External factors and environmental exposures play a part as well. Exposure to ultraviolet (UV) light from sources like welding arcs, sunlamps, or intense sun glare off snow can cause photokeratitis, which presents with SPK. Similarly, chemical splashes or exposure to smoke can directly harm the corneal surface cells. Certain medications, particularly the preservatives found in some topical eye drops, can be toxic to the cornea with long-term use.
Diagnosis and Medical Management
An eye doctor diagnoses SPK during a comprehensive eye exam using a slit lamp. This device allows for a highly magnified view of the eye’s structures. To make the damaged areas visible, the doctor applies a diagnostic dye, most commonly fluorescein, to the eye’s surface. This dye stains the areas where epithelial cells are missing, which then appear as fine, punctate speckles under a cobalt blue light.
The treatment for SPK is not directed at the sign itself but at resolving its underlying cause. For instance, if SPK is caused by dry eye syndrome, the primary treatment involves prescribing lubricating eye drops, known as artificial tears, gels, or ointments. If contact lens overwear or poor hygiene is the culprit, the immediate step is to temporarily discontinue lens use and receive education on proper lens care.
An antibiotic ointment may be prescribed to prevent a secondary infection while the cornea heals. For SPK caused by infections, specific antimicrobial therapy is required, such as antiviral drops for a viral infection or antibiotic drops for a bacterial one. When allergies are the cause, antihistamine eye drops are used to control the allergic response, and in cases where medication toxicity is suspected, switching to preservative-free formulations is often the solution.