Vernal Keratoconjunctivitis (VKC)
A classic presentation of VKC.
Signs and symptoms: VKC is a chronic, bilateral inflammation of the superior and limbal palpebral conjunctiva. The warmer the climate, the greater its prevalence. Onset typically occurs between ages 3 and 25 years. Males typically are affected more than females.
Symptoms often include severe itching with thick, ropy discharge. In most cases, patients have a history of allergies or infantile eczema. The important clinical signs include large conjunctival papillae on the back of the superior tarsus; raised Horner-Trantas dots (gelatinous, white clumps of degenerated eosinophils usually located at the superior limbus); areas of superficial punctate keratitis (SPK) and, in severe cases, well-demarcated, sterile corneal shield ulcers, located superiorly. You can differentiate VKC from atopic keratoconjunctivitis (AKC) based on age, location, dermatitis and lack of seasonal variability.
Pathophysiology: Allergic responses are the immune system's overreaction to foreign substances known as immunogens or allergens. The key component of the vernal ocular allergic response is the eosinophil. Vernal conjunctivitis, which is IgE-mediated, is the only ocular disease to involve solely Type I hypersensitivity. Involvement of secondary inflammatory cells--particularly eosinophils (along with mast cells) resident to the substantia propria of the superior tarsus--can produce sequelae. Papillae with epithelial downgrowth form crypts, at the base of which lie mucus-producing goblet cells. Plasma cells and lymphocytes collect inside papillae stroma. Vernal shield ulcers develop in the upper regions of the cornea. The base of the ulcer is composed of abnormal mucus, fibrin and serum, deposited as a gray plaque. Friction secondary to the roughened superior conjunctiva erodes the corneal epithelium.
Management: Management of VKC is primarily aimed at reducing symptoms and preventing serious vision-threatening sequelae. The most effective treatment is to eliminate or avoid the allergen; however, this is often impractical. Cold compresses and artificial tears and ointments soothe, lubricate and may dilute the antigen. Topical decongestants such as naphazaline and phenylephrine produce vasoconstriction, reducing hyperemia, chemosis and other symptoms by retarding the release of chemical mediators. Topical antihistamines--Livostin, Patanol, Zaditor, Optivar--and oral antihistamines--Benadryl, 25mg tid--are also excellent therapies. Mast-cell stabilizers such as Alomide, Alocril, Alamast and cromolyn sodium can be useful before the disease flares or to keep it under control following acute treatment; however, mast-cell stabilizers often do little to abate the symptoms. NSAIDS such as Acular and Voltaren bid-qid may offer relief in moderate cases, with topical steroidal preparations--Pred Forte, Lotemax, Alrex or Pred Mild (prednisolone 0.12%, Allergan) bid-qid--reserved for more severe presentations.
Patients with shield ulcers should receive additional treatment involving aggressive cycloplegia (atropine 1%, homatropine 5% or scopolamine 0.25%, bid) and topical antibiotic drops--Tobrex (tobramycin, Alcon), Ciloxan (ciprofloxacin, Alcon); Ocuflox (ofloxacin, Allergan), Quixin (levofloxacin, Santen) or Polytrim (trimethoprim/polymyxin B, Allergan). Also consider prescribing the mucolytic acetylcysteine (Mucomyst 10% or 20%), q4-6h. A low-water-content, thin hydrogel lens can reduce the interaction between the lid and cornea. When the corneal lesion re-epithelializes, you can then initiate topical steroids.
- In cases that occur chronically, consider treating in advance with loading doses of topical mast-cell stabilizers (Alomide, Alamast, Alocril or cromolyn sodium) or mast-cell-stabilizing antihistamines (Patanol or Zaditor). This is an attempt to retard the degranulation process, thus slowing, eliminating or reducing the debilitating consequences. If this is effective, maintain this therapy throughout the allergy season.
- Remember that mast-cell stabilizers will not affect the current symptoms but will instead lessen future reactions.
- Follow patients placed on supportive therapies (artificial tears or cold compresses) on an as-needed basis. Those receiving topical medications should return at one week, with close monitoring afterward. Patients on top ical steroids should undergo periodic IOP measurement. Patients treated for shield ulceration should return for follow-up every 1-3 days.