The lacrimal gland acini and ducts are damaged in the autoimmune disease. Rheumatoid arthritis is the most common, but systemic lupus erythematosus, Wegener’s granulomatosis, scleroderma, systemic sclerosis, and primary biliary cirrhosis may also be associated.
Sjögren’s syndrome is a triad of dry eye, dry mouth (xerostomia), and a collagen vascular disease. Blepharitis with a frothy tear film may be seen in tandem with dry eye. In more severe disease, filamentary keratitis can develop as well as corneal scarring. The upper half of the cornea is usually spared. Abnormal fluorescein or rose bengal staining of the corneal and conjunctival epithelium in the exposed interpalpebral fissure (at 3 and 9 o’clock) of the lower third of the cornea is often present. Signs of dry eye include a decreased tear meniscus, debris in the tear film, conjunctival injection, and superficial punctate keratitis and conjunctivitis. In the early stages, ocular symptoms may be more impressive than what is found on the examination. What are the most common signs of dry eye? Symptoms are worse in low-humidity environments, such as those with central air and in an airplane, during prolonged reading or driving with a decreased blink rate owing to increased concentration, and windy conditions. Cigarette smoke can be extremely irritating. A dry or dusty environment may cause more difficulties in patients with dry eye than in others. Usually, the symptoms are worse in the afternoon and evening and better on awakening. Mixed: This combines features of the other two.īurning, irritation, foreign body sensation, light sensitivity, and blurred vision. Intrinsic factors are meibomian gland dysfunction, eyelid abnormalities (i.e., Bell’s palsy, ectropion) or corneal surface changes such as dellen, and poor blink. Lacrimal deficiency or obstruction and systemic drugs are other causes.Įxtrinsic causes are vitamin A deficiency, topical drugs and their preservatives, contact lens wear, and environmental factors such as low humidity or allergens. Ten percent of severe dry eye patients have Sjögren syndrome. Hyposecretive (i.e., Sjögren or non-Sjögren syndrome): The aqueous component is low. Of course, a normal tear film makeup is essential. What is necessary for the normal resurfacing of the tear film?Ī normal blink reflex, normal lid anatomy and contour, and a normal corneal epithelium. This is becoming more common with the increase in gastric bypass procedures. Vitamin A deficiency can result in the loss of goblet cells. Patients with other conjunctival disorders that accompany conditions such as aniridia may also have dry eyes. Patients with cicatricial ocular pemphigoid, Stevens-Johnson syndrome, chemical burns (especially alkali), and graft-versus-host disease in bone marrow transplantation may have dry eye. What diseases of the conjunctiva can cause dry eye?Ĭonjunctival scarring can injure the goblet cells. It covers the villus surface of the corneal epithelium, converting it from a hydrophobic surface to a hydrophilic one, thus allowing the aqueous layer to lubricate the cornea. What is the function of the inner mucin layer? If deficient, hyposecretive dry eye results, as found in Sjögren’s syndrome. It supplies oxygen from the atmosphere to the corneal epithelium, washes away debris, and has antibacterial properties due to IgA, lysozyme, and lactoferrin present within it. What is the function of the aqueous middle layer? Also, an abnormal lid contour, as in ectropion or lid tumor, or poor blinking, found in Bell’s palsy, can cause outer lipid layer dysfunction.
It could be caused by oil deficiency, as in meibomian gland dysfunction (i.e., blepharitis). What causes dysfunction of the outer lipid layer? If it is dysfunctional, evaporative dry eye will result. It retards evaporation of the aqueous middle layer. What is the function of the outer lipid layer? The innermost layer is a mucin layer produced by conjunctival goblet cells. The middle layer, the thickest, is composed of aqueous produced from the main and accessory lacrimal glands. The outer layer is a thin lipid layer produced by the meibomian glands, which open along the upper and lower lid margins. The normal tear film is made of three components. What are the components of the tear film? The normal tear film is a 1.0-mm convex band with a regular upper margin. The resulting changes in the ocular surface can cause ocular discomfort, scarring, and, in severe cases, loss of vision and perforation. A dry eye, or keratoconjunctivitis sicca, is a condition in which the tear film is abnormal and cannot lubricate the anterior surface of the cornea adequately.
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