What Are Bitot’s Spots?

Bitot’s spots are a common ocular symptom of vitamin A deficiency (VAD) and xerophthalmia, a progressive disease. If left untreated, xerophthalmia can damage the cornea or cause blindness, especially in children.

In this article, we’ll look at:

• What causes Bitot’s spots
• How they are diagnosed
• Symptoms and associated conditions
• Available treatment options

First described by Pierre Bitôt in 1863, Bitot’s spots (also called Bitôt spots or Bitot spots) are dry-appearing whitish, gray, or opaque deposits that form on the sclera (whites of the eye). Bitot’s spots are made up of dry conjunctival epithelium cells.

The conjunctiva is the mucous membrane covering the front layer of the eyeball as well as the inner side of the eyelids. Vitamin A deficiency or hypovitaminosis is the main cause of dried-out conjunctiva and blindness in children.²

How are Bitot’s Spots Characterized?

A Bitot spot is often triangular-shaped. Its base is at the temporal limbus, and its apex extends toward the outer canthus (where the upper and lower eyelids meet).

The dry, elevated surface of a Bitot’s spot may appear frothy or foamy. These spots may also be more pronounced in areas of the eyeball exposed to ultraviolet light, wind, smoke, and dust.

In severe cases of VAD, corneal scarring and ulceration may occur. Depending on the scar’s location, light may be obstructed, causing poor vision.

How Common Are Bitot’s Spots in Children?

Bitot’s spots are more common among children in developing countries due to the high prevalence of VAD in such regions.

According to a children’s study done in India, the prevalence rate of Bitot’s spots among children with xerophthalmia was 0.9% in children under six years of age and 3.3% in children above six years.⁷ Studies done in Ethiopia indicated a prevalence of 0.5% among preschool children.⁸

Over the years, scientists have noted a downward trend in the prevalence of vitamin A deficiency. This is likely due to interventions such as health education and dietary diversification among affected populations. 

What Causes Bitot’s Spots?

The two leading causes of Bitot’s spots are Vitamin A deficiency and exposure to elements.

Vitamin A deficiency (VAD)

Bitot’s spots occur due to drying of the conjunctival epithelium, a common sign of vitamin A deficiency (VAD). According to research, fat-soluble vitamin A plays a vital role in vision, immune system competency, growth, and reproduction.⁴

Causes of vitamin A deficiency include:

• Malnutrition (low intake of vitamin A-rich foods/supplements especially in developing countries)
• Conditions causing malabsorption (e.g., celiac disease, Crohn’s disease, cirrhosis, etc.)
• Poor maternal nutrition
• Alcohol abuse
• Zinc deficiency
• Gastrointestinal disorders

In the eye, vitamin A supports the production of mucins. Mucins are special proteins that make up the mucus membrane of the conjunctiva. Without this protein, the conjunctiva dries out or changes its form.

Vitamin A deficiency can also cause interaction between the protein keratin (found on the conjunctiva cell surface) and the bacteria Corynebacterium xerosis, causing the Bitot’s spots surface to appear foamy.³ 

Exposure to Elements

Exposure to elements like ultraviolet (UV) rays, wind, smoke, and dust can sometimes cause Bitot’s spots, especially in adults.⁵ This can happen even in patients with no history of VAD.

Bitot’s spots are fully reversible with oral vitamin A replacement. However, if left untreated, vision loss may occur.

How are Bitot’s Spots Diagnosed?

Diagnosis of Bitot’s spots is done by carefully examining the patient’s ocular structures, blood, and clinical history. 

• General exam. To examine the patient’s weight, signs of jaundice, and abdomi­nal palpation; done to rule out liver disease
• Ocular exam. To check for possible subconjunctival fi­brosis and symblepharon; includes tests like Schimmer, Rose Bengal, and Lissamine Green
• History. To assess if the patient has a history of low Vitamin A intake or impaired absorption

Symptoms of Bitot’s Spots

The following are symptoms and conditions associated with Bitot’s spots:

1. Xerosis (drying) of conjunctiva and cornea. Drying of the conjunctiva and cornea is due to the loss of goblet cells and mucin. A dry conjunctiva appears wrinkled and dull. On the other hand, a dry cornea will appear dull and hazy.
2. Night blindness (nyctalopia). VAD’s effects on the production of rhodopsin (light-sensitive pigment in the retina) cause difficulty seeing at night or in dim light. In severe cases, total blindness can occur.
3. Corneal scarring. Bitot’s spots can damage the cornea, causing scarring. Depending on the location of the scar, vision may be impaired.
4. Xerophthalmic fundus. These are structural changes in the retina (the light-sensitive layer at the back of the eye). The back of the retina may appear to have scattered small, white, deep lesions.
5. Keratomalacia. This refers to the softening of the cornea, especially in severe VAD cases. A softened cornea becomes prone to infections, ulcers, and rupture, which can endanger eyesight. 

These symptoms and conditions can lead to blindness and require immediate medical attention.

How are Bitot’s Spots Treated?

Bitot’s spots are treated by addressing the underlying cause–vitamin A deficiency (VAD). Adults and infants with xerophthalmia can benefit from high doses of vitamin A.

According to the American Academy of Ophthalmology, most cases of Bitot’s spots will improve within two weeks of high-dose vitamin A therapy.¹ However, retinal effects such as night blindness may take longer to heal (about four weeks).

Preventing Vitamin A Deficiency and Bitot’s Spots

On top of the ocular manifestations of vitamin A deficiency, affected children are at a high risk of blindness or death. The good news is that the conditions are preventable and reversible before things worsen.

Below are strategies to ensure adequate vitamin A intake:

• Eat vitamin A-rich foods. Includes dark green leafy vegetables, yellow vegetables, fruits, carrots, milk, liver, etc.
• Properly manage diseases. Some diseases enhance vitamin A depletion, such as enteric infections (that cause diarrhea)
• Take vitamin A supplements. Especially beneficial for people with poor or limited diets or those with a condition that causes vitamin A depletion
• Proper vigilance. Watch out for signs of vitamin A deficiency in adults and children and consult the relevant medical professionals for early management

Summary

• Biot’s spots are dry-appearing triangular-shaped, whitish, gray, or opaque deposits that form on the sclera (whites of the eye). They are made up of dry conjunctival epithelium cells.
• The dry, elevated surface of a Bitot’s spot may appear frothy or foamy.
• The two main causes of Bitot’s spots include vitamin A deficiency (VAD) and exposure to elements such as UV rays, dust, wind, etc.
• If left untreated, Bitot spots can cause preventable blindness. Diagnosing involves carefully examining the patient’s ocular structures, blood, and clinical history. 
• Bitot’s spots are reversible through proper management of vitamin A deficiency. Experts recommend a high dose of Vitamin A as the primary course of treatment.