Investigating and treating ocular allergy

Damian Lake, consultant ophthalmologist and specialist in ocular surface conditions, opened his 100% Optical session by providing a definition of allergy as “an abnormal immune response to harmless substances that we find in our environment.”

“Ocular allergy, we see very frequently,” Lake said. “Patients come to our practices with varieties of symptoms and signs, some of which we may pick up and some of which we may not. The objective today is to talk through those symptoms and signs, and look at the classification of ocular allergy.”

A review and update on current treatments, as well as those coming in the future, would also be provided, Lake said.

He added: “As we now live in a much cleaner environment than in the past, we’re not exposed to allergens at an early age and therefore we develop allergies later on.

“Conversely, there’s also the environmental argument that increased exhaust fumes, etc, are also contributing to allergies. As we don’t know the incidence of allergies in 1800, it’s difficult to tell whether it’s going up or going down.”

Lake noted that allergies currently cost the NHS £900 million in primary care.

He went on to outline different types of allergies that a person might encounter, including variations of conjunctivitis: atopic, vernal, seasonal, and perennial.

“By far the commonest that we see is seasonal allergic conjunctivitis, although it’s likely that that has been missed or misdiagnosed in a large number of people,” Lake said.

He added: “The thread that runs through all these allergic conditions is the presence of immunoglobulin E. The clinical signs for each of these have some overlap.”

Allergic eye disease investigations

“The history, symptomatology and clinical findings are not easy in allergic conditions,” Lake said. “You can understand, in the mild end of the scale, why a lot of these patients get missed. There may be a lot of people in the community who are not getting treatment, or don’t understand what condition they’ve got.”

He asked: “How do we separate these patients who may or may not have a different type of conjunctivitis?”

Lake highlighted patch testing as vital when investigating this field, as “all allergic patients have a systemic response.”

A skin prick or a blood test can also assess the systemic response, Lake said.

He noted that atopic allergies have no seasonal variation, and that sufferers are often older adults.

Photophobia, tearing, itching, raised B cells and presence of mucus can also be signs of an atopic allergy, Lake said.

He identified some potential clinical features as:

• Changes in the skin of the eyelids
• Dennie-Morgan lines
• Presence of trantas dots
• Presence of cataracts
• Ulcers on the cornea
• Swollen conjunctiva
• Fibrosis due to chronic inflammation.

Lake noted that atopic allergies are also linked to keratoconus, so a test for this should also be carried out.

He also noted that “it’s much more common to get herpes simplex virus keratitis in atopic people, because their T cells are deficient.”

Atopic people are also more likely to get cataracts and retinal detachments, he said.

Clinicians should investigate the papillae, whether there are inflammatory cells or oedema, meibomian gland disfunction, or whether the conjunctiva is thickened, Lake advised.

“People with atopic conditions get ocular surface tumours more commonly than others,” he noted.

He also emphasised that eczema is common in atopic people, although often the patient may not automatically relate this to redness in their eyes.

Lake went on to discuss vernal allergic reactions, which he said may appear in teenage or adulthood but are relatively rare in the UK. Vernal conditions are more common in Africa, he said.

He noted that highly pigmented skin has a different pattern to that which is less pigmented.

A vernal allergic reaction at an advanced stage may present with shield ulcers, Lake said.

“The symptoms in vernal are itch, tearing, photophobia, and a lot more mucus. The photophobia, particularly at the more severe end of the spectrum, is such that they’re wearing sunglasses or closing the curtains during the day,” he explained.

He noted that there may be seasonal variation, and that 40% of sufferers have an atopic history, which might make diagnosis more difficult. Some may also have a genetic predisposition.

Lake added that vernal allergic reactions are more common in males than in females.

A clinical feature that practitioners should not miss is a small group of giant papillae, often amongst a sea of otherwise normal papillae, with mucus stuck in between, Lake said.

He explained that practitioners can identify this by flipping over the top lid.

“If you don't flip over that top lid, you may just see a vaguely red watery eye,” Lake explained. “So, it’s important to do so, even if it’s difficult.”

He also noted the potential presence of cataracts, which could be sight-threatening, in these patients.

Potential clinical features were identified as:

• Limbal signs
• Ectasia
• Giant papillae
• Cataract
• Ptosis (drooping of the eyelid)
• Punctate epithelial erosions on the cornea
• Corneal ulcers
• Potential calcification.

Lake emphasised that vernal allergic reactions are under-diagnosed, and can be vision threatening.

They also cause more scarring than atopic allergic reactions.

In terms of investigations, Lake noted that optometrists may again “have to deal with the associated keratoconus.”

Atopic keratoconjunctivitis and vernal keratoconjunctivitis can both be vision threatening, he emphasised.

“In summary, look out for atopic; look out for vernal,” Lake said. “Atopic maybe is more common than vernal, but they’re both vision threatening, so they’re going to need long-term management; they’re going to need multi-agency treatment.”

He added: “It’s worthwhile referring those in to get that treatment up and running early, because these are often teenagers, or even younger sometimes.”

When advising patients on prevention, he noted that closing windows and avoiding air-conditioning in the car can be helpful, as can using an in-car air filter.

Showering more often, changing clothes and regularly washing bed sheets are also helpful, Lake said.

He also noted that exercise can improve allergy outcomes.

“You’ll get parents who are protective and say ‘no, he can’t go out and do the exercise, because it’s going to cause him to be allergic.’ But the evidence states that kids who do more exercise get fewer allergies,” Lake said.

He also advised using a cold compress to relieve symptoms.