Ocular Allergy With No Corneal Involvement

Clinical Evaluation

Risk Factors

The different types of allergic conjunctivitis with corneal involvement have different risk factors.³

• Vernal Keratoconjunctivitis (VKC): This is a more severe form of allergic conjunctivitis, typically seen in children and young adults. It is rarer than SAC and PAC, but due to possible corneal involvement, it is potentially a more serious condition. VKC has a mean age of onset of 7 years and the majority of cases (85%) have an onset prior to age 10 years.⁴ It is found most commonly in males.⁵
• Atopic Keratoconjunctivitis (AKC): AKC is a chronic and severe form of allergic conjunctivitis often associated with atopic dermatitis (eczema)⁶ and other systemic allergies. It is the most potentially blinding of all the ocular allergies. Similar toVKC, AKC is more common in males. The condition typically begins in the late teens or early twenties with a peak severity occurring between ages 30 to 50 years.⁶

Signs

The different types of allergic conjunctivitis have different presenting signs.

Vernal Keratoconjunctivitis:^{3, 7}

• Discharge that is stringy white and mucous
• Palbebral
  • Hyperaemia and chemosis of the conjunctiva
  • Giant tarsal papillae
• Limbal
  • Hyperaemia and oedema causing thickening
  • Trantas Dots (small white/yellow accumulations of eosinophils which may be unilateral)
• Corneal (Usually upper third)
  • Punctate epithelial keratopathy
  • Macro-erosions
  • Plaque or shield ulcer
  • Subepithelial scarring
• Unlike SAC and PAC the signs may be different from one eye to the other
• Patients with VKC may also have keratoconus and atopic cataract (anterior or posterior polar)

Atopic Keratoconjunctivitis:^{3, 8}

• Thickened eyelids with crusting
• Blepharitis (staphylococcal)
• Conjunctival hyperaemia
• Giant papillary hypertrophy
• Limbal inflammation
• Punctate corneal epitheliopathy which may progress to macro erosion, plaque formation, subepithelial scarring, neovascularisation, pannus, thinning and possible spontaneous perforation.
• There is a greater likelihood that these patients develop herpes simplex keratitis, keratoconus, atopic cataract, and retinal detachment.

Investigations

History

A clinical history will help clinicians to differentiate ocular allergy from other potential eye conditions.³ Nearly 49% of patients who suffer from VKC have a family history of atopic disease such as asthma, rhinitis, or eczema. VKC is also commonly associated with a personal allergy history, which might include asthma, rhinitis, or atopic eczema. Therefore, it’s important to check for signs of eczema and other atopic symptoms during the examination of an AKC patients. As for example, distinguishing systemic manifestations of atopic dermatitis can aid in distinguishing AKC from VKC.

Slit Lamp Examination:³

This will help clinicians to differentiate ocular allergy from other potentially sight threatening ocular conditions, and the following may be considered in examining these patients:

• Evaluate lids and lashes to look for swelling, thickening, signs of eczema, and blepharitis.
• Look for conjunctival chemosis
• Check and grade conjunctival redness.
• Look for limbal changes.
• Evert eyelids to look for and grade papillae and hyperaemia
• Check cornea (No corneal involvement in acute allergic, seasonal, perennial or giant papillary conjunctivitis)
• Check anterior chamber
• Look for atopic cataract
• Check for possible retinal detachment

Diagnostic Methods

• Skin Testing: Utilising a skin-prick test, which has been reported to demonstrate positivity in only 20% of patients with ocular allergies.⁹
• Conjunctival Provocation Test: Involves the application of allergens topically into the conjunctival sac to elicit a response.¹⁰
• Biopsy of Conjunctiva: Involves obtaining cytology specimens from the conjunctiva, with a focus on identifying the presence of eosinophils and mast cells. The presence of eosinophils during an allergic reaction is recognised as diagnostic for allergy.¹⁰
• Tear Fluid Analysis: A measurement of IgE levels greater than 16 IU/ml in tear fluid can be indicative of allergic conjunctivitis. However, tear analysis does not differentiate between different types of ocular allergies.¹⁰

Management & Advice

When treating VKC and AKC there are similarities between these conditions and allergies with no corneal involvement. However, there are differences as well and the various options that clinicians can choose from are:

Non-Pharmacological Treatments: Allergy avoidance efforts can lead to a 30% reduction in symptoms,¹¹ although eliminating the triggering agent may not always be feasible. This approach may involve challenging lifestyle adjustments, such as parting with pets, avoiding enjoyable activities, or even relocating to areas with different environmental conditions.

• To mitigate allergic triggers, various strategies may be employed:
  • Opting for synthetic fibre pillows and using impermeable mattress covers.
  • Regularly washing bed linens, pillowcases, and blankets in hot water.
  • Eliminating upholstered furniture, soft toys, and carpets from living spaces.
  • Implementing measures to exterminate cockroaches and minimize exposure.
  • Installing dehumidifiers in damp areas like basements.
  • Utilising heat-steam treatments in homes.
  • Employing high-efficiency particulate air (HEPA) vacuums and filters.
  • Avoiding known food triggers.
  • Restricting pets to designated areas or keeping them outdoors.
  • Maintaining a rigorous cleaning routine in the household.

• It’s important to also avoid or control other non-allergenic triggers such as cigarette smoke, strong odours, irritating fumes, air pollution, cold temperatures, and high humidity if feasible.
• Cold compresses are effective in reducing vasodilation and providing temporary relief from symptoms.
• For AKC management of any associated staphylococcal blepharitis by using lid hygiene may be of benefit.

Pharmacological Treatments^{3, 7, 8, 12}

Artificial Tears

• Using artificial tears 2-4 times daily, or as needed, aids in diluting and removing allergens while providing ocular lubrication.

Mast Cell Stabilisers:

• Inhibit mast cell degranulation, reducing the release of inflammatory substances.
• Do not affect inflammatory mediators already released.
• Up to a 2-week loading period is needed for maximal efficacy.
• Not ideal for acute allergic conjunctivitis due to a delay of 2 to 4 days before effectiveness.
• Suitable for chronic use as an alternative to topical steroids when long-term treatment is necessary.
• Some patients may experience immediate relief from mast cell stabiliser drops, primarily due to their lubricating effect, although the pharmacological impact may take several days to manifest.

Steroids:

• Inhibit various inflammatory mediators, including synthesis of new histamine release by mast cells, inactivation of available histamine, mast cell degranulation, decrease in capillary permeability, and inhibition of phospholipase A synthesis.
• Topical steroids are often necessary for treating the acute phase of severe allergic conjunctivitis like AKC, VKC, and GPC. Once controlled, steroids should be tapered, and mast cell stabilisers and antihistamines should be used.
• Steroids can also reduce inflammation in corneal ulcers caused by toxic substances.
• However, long-term steroid use should be avoided to prevent intraocular pressure (IOP) elevation. Preferably, soft steroids should be used for short-term inflammation control.

Oral Anti histamine Medications:

• Systemic treatment for ocular allergies can reduce itching, hyperaemia, tearing, and swelling, but topical treatment yields a quicker and more effective response compared to oral systemic medications.
• Combining topical and systemic medications may offer better outcomes. Supplementing oral medications with topical agents can potentially lower the required dose of systemic drugs, thereby reducing possible side effects.
• Side effects of oral medications may include drowsiness, dry mouth, dry eyes, and blurred vision.
• Second-generation antihistamines have fewer side effects compared to older versions, but may still cause some dry eye symptoms.

Antibiotics

• Topical and systemic antibiotics may be used for any associated lid disease.

Clinicians should note that AKC and VKC may very often require a multidisciplinary approach with ophthalmology, dermatology, immunology and paediatrics. Topical or systemic immunosuppression may also be prescribed to control the condition.