Details, details

Visual acuity measured 20/20 in both eyes. Pupils, confrontation fields and ocular motility were all unremarkable. Gross external examination showed injected conjunctiva. The inferior lids were noticeably edematous, and the patient repeatedly rubbed her eyes and nose during the examination (figure 1, page 48).

Biomicroscopy revealed mild conjunctival edema, injection that was most prominent in the horizontal meridian, and injected, thickened lid margins. Neither the cornea nor conjunctiva stained with sodium fluorescein. Examination of the lower tarsal conjunctiva revealed multiple papillae (figure 2); upon eversion, the upper lid had a similar appearance. I didn't see any giant papillae (>1mm diameter).

I diagnosed uncomplicated allergic conjunctivitis associated with allergic rhinitis. The patient said she experienced no relief of her ocular symptoms from the oral antihistamine. We prescribed palliative measures of cool compresses, q.i.d. topical Systane drops (Alcon), and Patanol 0.1% ophthalmic drops (olopatadine hydrochloride, Alcon ) q.12 hours. One week later, the patient's conjunctival edema and injection had diminished considerably. She reported that her ocular itching was greatly improved and her other symptoms has resolved completely.

It's everywhere

Lauren's presentation is amazingly common. The incidence of allergy in general, and ocular allergy in particular, has increased over the past decade. According to the American Academy of Allergy, Asthma, and Immunology, 80 million people experience ocular allergy, and the incidence appears to be rising. Consider these statistics from the National Institute of Allergy and Infectious Diseases:

More than just itchy eyes

The increased prevalence of allergy has a direct effect on quality of life (QOL). A study of 377 adults with confirmed allergy asked participants to complete an SF-36 Quality of Life Health survey prior to treatment initiation. The survey measured eight QOL dimensions, including physical functioning, role limitation due to physical problems, role limitations due to emotional problems, social functioning, mental health and general health. All subjects had lower (poorer) scores on all scales compared with norms for the general U.S. population. After one year of treatment with allergy shots and an elimination and/or rotation diet, a second survey of the same subjects revealed improvement in all areas. 

These findings suggest that allergy symptoms affect QOL and that treatment may lead to measurable improvements. The authors concluded that doctors must recognize the QOL impact of allergy and offer patients treatment.

A British study of the impact of ocular allergy on QOL showed that individuals with seasonal allergic conjunctivitis (SAC) generally have a lower income because they more frequently miss work due to symptoms. These patients also reported a greater degree of ocular pain and discomfort than the control group. Interestingly, in a country with socialized health care, the out-of-pocket health cost for SAC-related care was £61 ($106.75) for control subjects and £124 ($217) for the SAC group. The researchers concluded that SAC is common, costly, chronic and causes reduced ocular and general QOL.

PAC Vs. SAC

Ocular allergy is rarely sight threatening. Rare conditions such as atopic keratoconjunctivitis or vernal keratoconjunctivitis have the potential to cause tissue damage and vision loss, but are not the focus of this article. The vast majority of cases are SAC or perennial allergic conjunctivitis (PAC). As its name suggests, SAC peaks during times of pollen release: typically spring and fall. Perennial allergy persists for more than nine months.

These conditions are not mutually exclusive; in fact, it's common for PAC patients to experience seasonal worsening of their condition during high pollen periods.

While pollens predominate as the causative agents in SAC, molds, animal dander and dust mite droppings are the primary allergens in PAC. Dust mites are unable to drink water and must obtain moisture from their environment. They are rare in climates where humidity levels fall below 50%. Animal dander consists of fur and shed skin particles. The primary allergen in animal dander is protein derived from animal saliva. These agents tend to be present in the home year-round.

Get to know the process

Successful management of ocular allergy depends on a thorough understanding of the allergic process. Allergy is an inappropriate immune response to a relatively harmless substance. When an allergen encounters a B-lymphocyte, the cell is converted into a plasma cell that produces immunoglobulins (IgEs) specific for the allergen. These IgEs reach the circulation and eventually adhere to the surface of mast cells.

When the allergen encounters a sensitized mast cell and bridges the gap between two molecules of IgE, the mast cell releases pre-formed granules of pre-formed mediators into the environment. These granules contain histamine as well as chymase, tryptase, heparin, eosinophil chemotactic factor, and neutrophil chemotactic factor. Antihistamines effectively block the action of histamine on:

►nerve endings (itching)
►blood vessel walls (injection and leakage of fluid into the extravascular tissue, which can lead to chemosis) and
►eyelids (edema).

Antihistamines do not influence the effects of other, preformed mediators.

Treatment options

Systemic antihistamines do not reach the eye in concentrations comparable to those achieved with topical medications. In fact, they may worsen ocular allergy symptoms because their drying effects can reduce tear volume and thus increase the concentration of pollens on the ocular surface. OTC topical antihistamine/decongestants reduce injection, but their effects are limited to only a few hours, after which rebound injection often occurs.

Research has demonstrated that mast cells in the lungs, which contain tryptase but not chymase (MT cells), behave differently from skin and conjunctival mast cells that contain both tryptase and chymase (MTC cells). There are also inherent differences in the way these types of mast cells react to medications. Topical "mast cell stabilizers" were originally developed for pulmonary disease and exert very little mast cell stabilization in MTC cells. For this reason, their usefulness in managing SAC and PAC is limited.

Steroids exert their palliative effects on allergy symptoms by blocking protein synthesis. Pulse doses of steroids for the initial quieting of SAC and PAC is acceptable therapy, but long-term use is not recommended. This palliative effect takes time, and the potential complications of chronic steroid use include IOP elevation and cataract formation.

In 1997, Alcon introduced Patanol, the first topical allergy medication that incorporated mast stabilization and antihistaminic effects. Other manufactures subsequently introduced Zaditor (ketotifen fumarate ophthalmic solution solution, 0.025%, CIBA Vision), Optivar (azelastine hydrochloride ophthalmic solution, 0.05%, Bausch & Lomb) and Elestat (epinastine hydrochloride 0.05%, Inspire). These products were initially developed for systemic dosing, and are approved as topical antihistamine/mast cell stabilizers.

While all four medications are superb antihistaminic agents, research demonstrated that with the exception of Patanol, the combination antihistamine-mast cell stabilizers did not effectively inhibit mast cell degranulation at their marketed concentrations.

Adjunct palliative measures often enhance the actions of topical allergy medications. Cold compresses constrict conjunctival vasculature, and frequent use of non-BAK (benzalkonium chloride) preserved artificial tears dilutes the concentration of allergen in the tear film. Thus I included both in my patient's treatment, as I discussed above.

Better QOL for both of you

Ocular allergy is a very common, chronic condition that can negatively affect our patients' quality of life. Effective management of allergic symptoms and conditions can improve their lives. And as my many grateful allergy patients will demonstrate, resolving their complaints will serve to grow your therapeutic practice.

References available upon request.

Dr. Townsend practices in multiple locations. He served for 11 years as a consultant at the VA Medical Center in Amarillo, Texas. He is Distinguished Visiting Clinician in Residence at the University of Houston College of Optometry and also serves as an adjunct faculty member there.