Bitot’s spots are distinctive patches on the conjunctiva, the clear membrane covering the white part of the eye. These dry patches are often triangular or irregular, with a foamy or frothy surface. They are often found on the temporal side of the cornea, near the limbus (the border between the cornea and sclera). First described in 1863 by French physician Pierre Bitot, these spots consist of keratinized conjunctival debris, sometimes mixed with bacteria.
The Link to Vitamin A Deficiency
Bitot’s spots are a clinical sign indicating a systemic deficiency of vitamin A. Vitamin A plays a role in maintaining the health of various epithelial tissues, including the conjunctiva. When vitamin A is lacking, conjunctival epithelial cells undergo squamous metaplasia, becoming more like skin cells and producing keratin.
This change leads to conjunctival xerosis, or dryness of the conjunctiva, a broader symptom of vitamin A deficiency. Other eye conditions related to vitamin A deficiency, collectively termed xerophthalmia, include night blindness (nyctalopia) and corneal xerosis. Night blindness, difficulty seeing in dim light, is often an earlier symptom than Bitot’s spots. Without adequate vitamin A, the eye cannot produce the necessary pigments for the retina to function properly in low light.
Diagnosis and Treatment
Diagnosis of Bitot’s spots involves a clinical eye examination performed by a healthcare professional. During this examination, the doctor will look for the characteristic dry, foamy, triangular patches on the conjunctiva. Other signs of xerophthalmia, such as conjunctival dryness or corneal changes, may also be assessed.
To confirm vitamin A deficiency, blood tests measuring serum vitamin A or retinol-binding protein levels are performed. Treatment involves high-dose vitamin A supplementation, usually orally. Improvement in Bitot’s spots is often observed within two weeks of starting vitamin A therapy. Vision problems like night blindness can also resolve with appropriate treatment, though retinal changes may take longer to respond.
Prevention and At-Risk Populations
Preventing vitamin A deficiency, and Bitot’s spots, centers on ensuring adequate dietary intake. Foods rich in vitamin A include animal sources like liver, fish, eggs, milk, and butter. Plant-based sources, containing provitamin A carotenoids like beta-carotene (which the body converts to vitamin A), include orange-fleshed sweet potatoes, carrots, pumpkin, mango, papaya, and dark leafy green vegetables such as spinach and kale. Many fortified foods, like some cereals and margarine, also contain added vitamin A.
Populations susceptible to vitamin A deficiency include preschool-aged children in developing countries, where malnutrition is common. Pregnant women are also at a higher risk. Individuals with malabsorption disorders (e.g., Crohn’s disease, cystic fibrosis), chronic liver disease, or a history of alcohol abuse may also have difficulty absorbing or storing vitamin A, increasing their risk.