Keratoconjunctivitis Sicca

The conjunctival and corneal surface epithelial cells need to be hydrated. If there is interruption of a continuous, unbroken layer of tears over the exposed surface, desiccation of surface cells leads to tissue damage and inflammation. 

There are 2 main types (although many patients have components of both types):

• Aqueous tear-deficient keratoconjunctivitis sicca is caused by insufficient coverage of the ocular surface by tears due to inadequate tear volume.

• Evaporative keratoconjunctivitis sicca (more common) is caused by insufficient coverage of the ocular surface by tears due to accelerated tear evaporation resulting from poor tear quality.

Aqueous tear-deficient keratoconjunctivitis sicca is most commonly an isolated idiopathic condition in postmenopausal women. It is also commonly part of Sjögren syndrome, rheumatoid arthritis (RA), or systemic lupus erythematosus (SLE or lupus). Less commonly, it is secondary to other conditions that scar the lacrimal ducts (eg, cicatricial pemphigoid, Stevens-Johnson syndrome, and trachoma). It may result from a damaged or malfunctioning lacrimal gland due to graft-vs-host disease, HIV (diffuse infiltrative lymphocytosis syndrome), local radiation therapy, or familial dysautonomia.

Evaporative keratoconjunctivitis sicca is caused by loss of the tear film due to abnormally rapid evaporation caused by an inadequate oil layer on the surface of the aqueous layer of tears. Symptoms may result from abnormal oil quality (ie, meibomian gland dysfunction) or a degraded normal oil layer (ie, seborrheic blepharitis). Patients frequently have acne rosacea.

Drying can also result from exposure due to inadequate eye closure at night (nocturnal lagophthalmos or Bell or facial nerve palsy) or from inadequate frequency of reapplication of tears to the cornea due to an insufficient blink rate (eg, in Parkinson disease).

Systemic medications can cause or aggravate dry eyes. Different classes of medications contribute to different types of dry eye, as in the following examples:

• Aqueous tear-deficient dry eyes: Diuretics, anticholinergics, antidepressants, beta-blockers, antihistamines, decongestants, oral contraceptives

• Dry eyes due to poor eyelid closure: Major antipsychotics, adrenergic agonists, botulinum toxin injections

Patients report burning; a gritty, pulling, or foreign body sensation; or photosensitivity. A sharp stabbing pain, eye strain or fatigue, and fluctuating blurred vision may also occur. Some patients note a flood of tears after severe irritation. Typically, symptoms fluctuate in intensity and are intermittent. Certain factors can worsen symptoms:

• Prolonged visual efforts (eg, reading, working on the computer, driving, watching television)

• Local environments that are dry, windy, dusty, or smoky

• Dehydration

Symptoms lessen on cool, rainy, or foggy days or in other high-humidity environments, such as in the shower. Recurrent and prolonged blurring and frequent intense irritation can impair daily function. However, permanent impairment of vision is rare.

With both types, the conjunctiva is hyperemic, and there is often scattered, fine, punctate loss of corneal epithelium (superficial punctate keratitis

With the aqueous tear-deficient type, the conjunctiva can appear dry and lusterless with redundant folds. With the evaporative type, abundant tears may be present as well as foam at the eyelid margin. Very rarely, severe, advanced, chronic drying leads to significant vision loss due to keratinization of the ocular surface or loss of corneal epithelium, leading to sequelae such as scarring, neovascularization, infections, ulceration, and perforation.

• Schirmer test

• Tear breakup time (TBUT)

• Ocular surface staining

Diagnosis is based on characteristic symptoms and clinical appearance. The Schirmer test, tear breakup time (TBUT), and ocular surface staining may differentiate the type. These tests are done before instilling drops of any kind.

The Schirmer test determines whether tear production is normal. After blotting the closed eye to remove excess tears, a strip of filter paper is placed, without topical anesthesia, at the junction of the middle and lateral third of the lower eyelid. If < 5.5 mm of wetting occurs after 5 minutes on 2 successive occasions, the patient has aqueous tear-deficient keratoconjunctivitis sicca. With evaporative keratoconjunctivitis sicca, the Schirmer test is usually normal.

To determine the TBUT, the tear film is first made visible under cobalt blue light at the slit lamp< 10 seconds) is characteristic of evaporative keratoconjunctivitis sicca.

If aqueous tear-deficient keratoconjunctivitis sicca is diagnosed, Sjögren syndrome should be suspected, especially if xerostomia is also present. Serologic tests and labial salivary gland biopsy are used for diagnosis. Patients with primary or secondary Sjögren syndrome are at increased risk of several serious diseases (eg, primary biliary cholangitis, non-Hodgkin lymphoma). Therefore, proper evaluation and monitoring are essential.

Several newer tests are being developed to help diagnose keratoconjunctivitis sicca. These include instruments for imaging the eyelid oil glands (meibography), measuring the quality of the tear lipid layer, and tear osmolarity. Results can vary (eg, from day to day) and may correlate poorly with clinical findings. Also, an office test for ocular surface inflammation (that measures the increased matrix metalloproteinase-9 in tears) is also available. However, the clinical utility of these tests is still uncertain.

• Sometimes occlusion of nasolacrimal punctum or tarsorrhaphy

Guidelines are available from the American Academy of Ophthalmology (see Dry Eye Syndrome

Staying hydrated, using humidifiers, and avoiding dry, drafty environments can often help. Not smoking and avoiding secondary smoke are important. Most evidence shows that neither diet nor supplements, such as omega-3 fatty acid (1), improve dry eye disease.

In recalcitrant cases, occlusion of the nasolacrimal punctum (punctal occlusion or cautery) may be indicated. In severe cases, a partial tarsorrhaphy can reduce tear loss through evaporation.

2). These drops sting and may take months before an effect is noticed.

Punctal Plug

Image

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Patients with evaporative keratoconjunctivitis sicca often benefit from treatment of concomitant blepharitis and associated acne rosacea with measures such as the following:

• Warm compresses applied (eg, for 5 to 10 minutes 1 to 2 times a day), infrared or automated heating and massaging devices to help increase oil flow onto the eye surface and increase the amount and effectiveness of lipids in the tear film, thereby decreasing tear evaporation

• 3)

• Lid hygiene: Eyelids can be cleaned (with eyes closed) with dilute baby shampoo or eyelid margin scrubs

Because of the variability of symptoms, validated questionnaires can help monitor response to therapy.