There are a number of systemic diseases that can lead to dry eye. Although some individuals may have ocular surface disease in and of itself, numerous systemic diseases include an ocular component that manifests as dry eye. Knowing the systemic cause of the ocular surface disease can aid us in the management of dry eye disease. The most common associations between systemic diseases and dry eye are autoimmune disorders such as Sjögren's syndrome and rheumatoid arthritis (RA).¹ Skin disorders such as rosacea are also likely to have a dry eye component (i.e., evaporative dry eye or meibomian gland dysfunction).² And finally, some systemic medications can lead to dry eye.

Systemic Diseases Associated with Dry Eye
Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects approximately 2% of the US population over 60 years of age.³ More than 90% of people with RA have dry eye.⁴ Up to 31% of patients with rheumatoid arthritis have a co-existing Sjögren's syndrome with dry eye.⁴ Sjögren's syndrome is one of the most prevalent autoimmune disorders affecting upwards of four million Americans.⁵ Sjögren's syndrome has its own complexities: its pathogenesis is obscure, it presents with both dry eyes and dry mouth, and it can present as primary or secondary Sjögren's syndrome. Dry eye syndrome is the most common ocular feature of systemic lupus erythematosus and is often associated with secondary Sjogren's syndrome.⁶ Thyroid eye disease is a common systemic disease associated with dry eye due to thyroid hormone imbalance and exophthalmos-related corneal exposure.⁷

One of the most common ocular manifestations of diabetes is dry eye disease.⁸ More than half of patients who have diabetes experience dry eye symptoms (54.3% in one study), such as burning and foreign body sensation, and suffer from ocular dryness.⁹ Reflex tearing has been demonstrated to be significantly decreased in insulin dependent diabetics.¹⁰

Systemic Medications
Numerous systemic medications can have ocular side effects producing a dry eye, including anticholinergic drugs, e.g., antidepressant, antipsychotic, anti-Parkinson's disease, and antihistamine drugs. Any systemic medication that dries mucosal surfaces or slows down the activity of mucosal surfaces may produce dry eye. If a medication causes dry mouth it will also cause dry eye. Some of the leading causes of dry eye disease from systemic medications include antihypertensives, beta-blockers,¹¹ cholesterol-lowering medications,¹² anticoagulants/aspirin therapy (which may also aggravate the condition, as they are secreted in the tear film), genitourinary medications such as hormone therapy (both estrogen and androgen),¹³ psychogenic medications,¹⁴ and dermatology treatments (such as isotretinoin).¹⁵

Almost 75% of patients taking glaucoma medications have some signs and symptoms of dry eye. This is a direct result of the preservatives in the medications, the side effects of the active ingredients, and the overall age group typically affected by glaucoma.¹⁶ Instillation of any eye medications, especially when they are instilled frequently (e.g., more than four drops a day), may prevent the normal maintenance of the tear film and cause dry eye symptoms.

Dry eye and ocular surface disease is a major concern in today's optometric practice. Don't forget to research the role of systemic diseases and systemic medications in your patients with dry eye disease.

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