Superficial Punctate Keratitis (SPK) is a frequent and often uncomfortable eye condition involving damage to the corneal surface. The cornea is the clear, outermost layer of the eye. This damage manifests as tiny, scattered lesions on the epithelium, which is the protective outer layer of the cornea.
What Superficial Punctate Keratitis Means
Superficial Punctate Keratitis is a descriptive term indicating the physical appearance and location of the problem. “Keratitis” refers to inflammation of the cornea, while “superficial” indicates the damage is limited to the epithelial layer. “Punctate” describes the characteristic pattern of multiple small, dot-like erosions or spots across the corneal surface.
These lesions are areas where corneal epithelial cells have been shed or damaged. Because the cornea is densely packed with nerve endings, this cellular disruption causes significant discomfort for the patient. Symptoms commonly include a gritty or foreign body sensation, excessive tearing, and eye redness. The condition can also interfere with vision, causing slight blurring because the damaged surface scatters incoming light, and sensitivity to bright light (photophobia). SPK is not a disease itself but a reaction of the cornea to an underlying issue.
Factors That Lead to SPK
A diverse range of triggers can cause the corneal epithelial damage seen in SPK, and identifying the specific cause is necessary for effective treatment. One major category includes infectious causes, particularly viruses. Adenovirus, often responsible for the common cold, can lead to widespread SPK as part of viral conjunctivitis.
Another infectious cause is the Herpes Simplex Virus, which can cause recurring episodes of keratitis. Thygeson’s superficial punctate keratitis is a specific form that presents with characteristic white-gray lesions on the cornea, and while its exact cause is unknown, it is presumed to be viral.
Environmental and mechanical factors represent another large group of causes, with contact lens misuse being a frequent culprit. Over-wearing lenses, poor hygiene, or a reaction to the lens solution can induce SPK by stressing the corneal surface. Exposure to ultraviolet (UV) light, such as from welding arcs or prolonged sun exposure without proper protection, can also cause photokeratitis.
Issues related to the ocular surface and systemic health can also lead to SPK. Severe dry eye syndrome is a common cause, as an unstable or insufficient tear film leaves the corneal cells vulnerable to damage. Drug toxicity from certain preserved eye drops can also induce SPK, as the preservatives or active ingredients irritate the epithelium over time.
Identifying and Managing the Condition
Confirming a diagnosis of Superficial Punctate Keratitis requires a specialized examination by an eye care professional. The condition is often invisible to the naked eye, so the physician uses an instrument called a slit lamp, which provides high magnification and a focused beam of light. To visualize the damage, a special staining dye, such as fluorescein, is applied to the eye.
The damaged or missing epithelial cells absorb this dye, causing the punctate lesions to glow bright green or yellow under a cobalt blue filter on the slit lamp. This technique allows the physician to clearly see the size, location, and pattern of the lesions, which helps in grading the severity and determining the underlying cause. For instance, SPK caused by dry eye often stains in the lower part of the cornea, while that from UV exposure is usually diffuse.
Management of SPK is entirely dependent on successfully addressing the identified cause. For supportive care, the primary approach involves the liberal use of preservative-free artificial tears and lubricating ointments to protect the corneal surface and promote healing. If the cause is contact lens-related, the lenses must be discontinued immediately to allow the cornea to recover.
Targeted medication is necessary in cases caused by specific infections, such as an antiviral drug for Herpes Simplex keratitis. If drug toxicity is suspected, the offending eye drop must be switched or stopped entirely. For severe cases, a temporary bandage contact lens may be placed on the eye to act as a protective layer, allowing the damaged epithelium to heal underneath without the constant friction of the eyelids.