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Superficial Punctate Keratopathy

ROUTINE — Cornea

Symptoms

  • foreign body sensation: a gritty, "sand-in-the-eye" feeling
  • pain and photophobia: light sensitivity that improves with topical anesthetic
  • tearing and redness: reflex tearing in response to surface irritation
  • blurred vision: often fluctuates with blinking as the tear film destabilizes

Clinical Findings

Clinical appearance

  • punctate epithelial erosions (pee): tiny, pinpoint areas of cell loss
  • fluorescein staining: the damaged spots take up green dye under cobalt blue light
  • lissamine green/rose bengal: stains devitalized cells (useful in dry eye)

Staining patterns (the diagnostic key)

  • superior (top 1/3): suggests lid pathology (evert for FB), vernal catarrh, or floppy eyelid
  • interpalpebral (middle band): suggests aqueous deficiency (dry eye) or neurotrophic causes
  • inferior (bottom 1/3): suggests blepharitis, exposure (incomplete closure), or drop toxicity
  • diffuse: suggests severe dry eye, chemical injury, or viral infection

Etiology

Key mechanical triggers

  • dry eye syndrome: aqueous deficiency or evaporative loss (MGD)
  • exposure: nocturnal lagophthalmos (sleeping with eyes open) or CN VII palsy
  • toxicity: preservatives (BAK) in chronic eye drops or toxic antibiotics (gentamicin)
  • mechanical: trichiasis (inward lashes), contact lens overwear, or foreign bodies

Specialized forms

  • thygeson spk: coarse, raised, gray-white lesions with a very quiet (white) eye
  • ultraviolet (welder's flash): diffuse, extremely painful SPK after UV exposure

Red Flags

  • reduced corneal sensation: check BEFORE anesthetic; suggests neurotrophic keratitis (post-herpes)
  • vertical linear scratches: high suspicion for a foreign body trapped under the upper lid
  • contact lens wearer: any SPK in a CL wearer requires a fluoroquinolone to cover Pseudomonas
  • non-resolving SPK: rule out Acanthamoeba or medicamentosa (toxicity from the treatment itself)

Investigations

Slit lamp workup

  • staining: note the location—it is the single most helpful clue to the etiology
  • lid eversion: mandatory if SPK is superior or linear to rule out a subtarsal foreign body
  • corneal sensation: test with a cotton wisp to screen for CN V dysfunction

Tear film assessment

  • tbut: count seconds until the tear film breaks up (normal >10 seconds)
  • schirmer test: measure tear production with paper strips if dry eye is suspected

Treatment

General management

  • lubrication: PF artificial tears q1h to q4h; lubricating ointment (e.g., Refresh PM) at bedtime
  • antibiotic cover: erythromycin or bacitracin ointment tid if erosions are confluent

Specific etiologies

  • contact lens: stop wear immediately; start prophylactic fluoroquinolone (e.g., moxifloxacin)
  • exposure: moisture chambers or nighttime taping/bland ointment
  • thygeson: low-dose topical steroids or cyclosporine drops

Clinical Pearl

SPK is a syndrome, not a diagnosis — always find the cause (dry eye, blepharitis, toxicity, exposure, trichiasis) because treating the epithelium without fixing the trigger is a losing battle.

Differential Diagnosis

  • • adenoviral keratitis (look for follicles and subepithelial infiltrates)
  • • herpes simplex keratitis (look for true dendrites with terminal bulbs)
  • • acanthamoeba (extreme pain, ring-shaped infiltrate in contact lens wearers)
  • • medicamentosa (red eye that gets worse the more drops the patient uses)

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