ALLERGY SEASON SHOULD RAISE YOUR SUSPICION, BUT DO YOUR DUE DILIGENCE

IT’S SPRINGTIME again. Have you been seeing more patients who have complaints of “itchy” “watery” and/or “burning” eyes? Allergic conjunctivitis, right? Or, not? Although it’s easy to equate these symptoms with allergic conjunctivitis, given their timing, we, as optometrists, must remember that the signs and symptoms of allergic conjunctivitis and dry eye disease (DED) are similar and, thus, muddy the diagnostic waters.

Here, I discuss how to distinguish these conditions, so you can make the proper diagnosis and, therefore, best manage these patients.

ETIOLOGY

Researchers believe allergies affect as many as 30% of adults and 40% of children, according to the Asthma and Allergy Foundation of America. Allergies are Type 1 IgE-dependent hypersensitivity inflammatory reactions.

In both acute (seasonal) and chronic allergic conjunctivitis, allergen exposure to the conjunctiva occurs, and the inflammatory cascade begins with mast cell degranulation, causing the release of inflammatory mediators (histamine). Examples of allergens: animal dander, dust, dust mites, chemical scents, such as detergents, and tree and grass pollen.

DED falls under two categories: aqueous deficient and evaporative. In the former, the lacrimal glands do not produce enough tears.

Evaporative DED occurs from the rapid evaporation of tear film from the ocular surface, caused by intrinsic disease (meibomian gland dysfunction, etc.) and extrinsic exposure (contact lens wear, etc.)

It’s important to keep in mind that a decreased tear film creates a higher concentration of allergens on the ocular surface. So, some patients may have both allergic conjunctivitis and DED.

DED risk factors: anticholinergic drugs (antihistamines, tricyclic antidepressants, etc.); cancer (systemic chemotherapy, ocular graft vs. host disease and radiation therapy); contact lens wear; digital display use (fixation can reduce blink rate); heating/cooling systems (humidity reduction); hormonal changes (chronic androgen deficiency, hormone replacement therapy and menopause); aging (weakened immune system); poor diet (excess caffeine and/or alcohol intake, low amounts of water and fatty acid intake, etc.); and previous ocular surgeries, such as LASIK (corneal nerve damage can disrupt the neural feedback loop).

A total of 25 million Americans suffer from DED, according to 2012 Market Scope data.

ALLERGY SYMPTOMS

• Burning
• Decreased contact lens (CL) wear time, decreased CL comfort
• Foreign-body sensation
• Itching (usually a primary clinical symptom)
• Photophobia

DED SYMPTOMS

• Blurred or fluctuating vision
• Burning (usually a primary clinical symptom)
• Dryness
• Fatigue
• Foreign-body sensation
• Grittiness
• Itching
• Poor comfort with contact lenses
• Stinging

ALLERGY CLINICAL SIGNS

• Chemosis
• Conjunctival hyperemia
• Conjunctival and palpebral inflammation
• Eyelid edema
• Mucous discharge
• Papillae
• Tearing

DED CLINICAL SIGNS

• Biofilm on lids
• Conjunctival and corneal staining
• Conjunctival redness
• Decreased aqueous production
• Decreased meibomian production and secretion
• Decreased TBUT
• Increased ocular surface inflammation
• Increased tear osmolarity
• Lid and ocular hyperemia
• Lid telangiectasia
• Meibomian gland atrophy/loss
• Meibomian gland obstruction
• Poor quality and secretion of meibum
• Tearing

DIAGNOSIS/MANAGEMENT

Several tests and instruments are available to aid you in making a definitive diagnosis. They are:

• Fluorescein staining. Perform this under blue light to see corneal staining and note decreased TBUT time, which is < 10 seconds.
• Interferometry. Use this to measure lipid layer thickness of the tear film.
• Lissamine green staining. View under white light. Lissamine green stains devitalized and membrane-damaged cells, making it ideal for viewing conjunctival staining.
• Meibography. Assess the morphology of the meibomian glands, specifically, gland loss, gland atrophy and gland shortening.
• Meibomian gland expression. Use this to grade the quantity and quality of the meibum released by the meibomian glands. Poor meibum is “tooth paste”-like in consistency, making it difficult to be expressed.
• Matrix Metalloproteinase-9 (MMP-9) test. Use this to identify the inflammatory marker linked with DED. A positive test occurs when > 40 ng/ml of MMP-9 is detected in the tears.
• NaFL staining. View this with cobalt blue light for punctate keratitis and to perform TBUT testing.
• Phenol red thread test. Use this to measure tear production. Wet lengths less than 10 mm are considered DED test results.
• Schirmer test. Use this to measure basal and reflex tear production. Measures of wetness shorter than 15 mm indicate reduced tear production.
• Sjö diagnostic test (Bausch + Lomb). This blood test identifies early Sjögren’s syndrome by combining traditional, and proprietary biomarkers.
• Tear osmolarity testing. Use this to examine the concentration of electrolytes in the tear film. High osmolarity numbers > 308 and differences between the eyes > 8 can indicate DED.
  If you determine the patient has allergic conjunctivitis, treatment consists of:
• Eye wash/artificial tears. Prescribe these to eradicate allergens from the tear film. If you diagnose the patient as having DED and allergic conjunctivitis, these items help to wash out the allergens.
• Cool compresses. Prescribe this to reduce the discomfort and irritation that stems from itching.
• Prescription anti-histamines/mast cell stabilizers. Prescribe these to decrease the number of allergens that stick to mast cells.
• Combination anti-histamine and steroid nasal sprays. These OTC items provide secondary efficacy.
• Topical steroids. Prescribe these for patients who have severe symptoms, such as chemosis.
• Daily disposable contact lenses. If you haven’t already, switch your allergic contact lens-wearing patients in to this lens type, as it prevents lens allergen build up.
• Peroxide-based contact lens solution. For patients who won’t get disposable contact lenses, this solution decreases the probability of harsh allergy symptoms because of its decrease in preservatives.
  (For a list of treatments for DED, see “Leave Them in Tears,” at tinyurl.com/DEDTears . Lifitegrast is not listed, because, as of press time, it had not yet received FDA approval for the treatment of the signs and symptoms of DED.)
  Should the patient have both allergic conjunctivitis and DED, prescribe:
• Artificial tears. These offer short-term relief. When needed more frequently, I recommend a more viscous tear or a non-preserved artificial tear because frequent use of preservative can cause toxicity to the cornea.
• Omega-3 and/or omega-6 supplements. These have been shown to decrease ocular surface inflammation and increase tear production.
• Topical treatments. This includes lifitegrast ophthalmic solution 5% (Xiidra, Shire) and cyclosporine ophthalmic emulsion 0.05% (Restasis, Allergan).
• Ester-based steroids. Prescribe these steroids for short-term use to decrease inflammation.

FUTURE TREATMENT OPTIONS

Future therapies being researched for allergy include subcutaneous allergy desensitization, such as sublingual immunotherapy (SLIT) — currently employed in the treatment of allergic rhinitis and asthma.

Research also is being done on selective glucocorticoid receptor agonists, kinase inhibitors and drugs that target toll-like receptors (proteins that play a role in one’s immune system) in the cornea and conjunctiva.

BE JUDICIOUS

While time of year should definitely raise our suspicions for one condition vs. the other, it’s important to remember that suspicion is not the same as fact.

Therefore, we must always take an accurate case history and use this, in addition to the patient’s clinical signs and symptoms, to lead us to the appropriate diagnostic tests and the answer.

Sure, that patient complaining of “itchy,” “watery” and/or “burning” eyes could have allergic conjunctivitis. But, it could also be DED, or both. Let’s properly identify all the contributing factors to arrive at a clear answer, so we can best manage our patients. OM

DR. JOHNSTON practices at Georgia Eye Partners. He focuses on ocular surface disease and has extensive experience in co-managing cataract and refractive surgery patients. He is a consultant and speaker for Abbott, Alcon, Allergan, BioTissue and Shire. Email him at drj@gaeyepartners.com, or visit tinyurl.com/OMcomment to comment.