Coloboma of Iris - Causes, Symptoms, Diagnosis, and Treatment

What Is Coloboma of the Eye?

Coloboma is a Greek term that means defect. Coloboma is a congenital defect of the eye. It can be present even before birth. Coloboma can be a defect of the eyelid, iris, or even the retina. This defect can appear as if there is a missing part. This missing part may appear as gaps or notches.

What Is Coloboma of the Iris?

Coloboma of the iris is the most common defect that occurs. Iris is the black-colored portion of the eye through which the light travels. It can affect one or both eyes. The lower and the inner quadrant may be missing, given this defect's keyhole appearance. It is most commonly found to occur with a small eyeball. If coloboma of the iris occurs with a defect of the retina, it can even lead to vision loss. It is known to occur in one out of every 10,000 people.

What Other Parts of the Eye Can Be Affected Due to Coloboma?

1. Coloboma of the Eyelid: Looks like a cleft or split in the eyelid. Most commonly occurs in the upper eyelid. It may be associated with Treacher-Collins syndrome or Goldenhar syndrome.

2. Coloboma of the Lens: It may look like a part of the lens is missing.

3. Coloboma of the Macula: The macula aids central vision and is part of the retina. A defect in the macula can lead to partial vision loss.

4. Coloboma of the Optic Nerve: This defect will lead to full or partial vision loss. The degree of vision loss depends on the extent of damage to the optic nerve. It may or may not be associated with other forms of colobomas, such as coloboma of the retina. This type of defect resembles the morning glory flower. Hence it may also be known as morning glory syndrome.

What Are the Symptoms of Coloboma of Iris?

Coloboma of the iris can be observed since or soon after birth. It has a characteristic keyhole appearance. Some very common symptoms associated with it are:

1. Appears as a split or notch in the pupil.

2. The pupil or iris may appear irregular in shape.

3. It may be associated with blurred vision.

4. The vision may be compromised in the affected eye. The vision may not be complete.

5. It may also be associated with double vision.

6. Ghosting of the images may occur.

7. Peripheral vision of the eye can be affected.

8. There can be a big blind spot-like feeling.

9. There can be a difficulty with depth perception.

What Causes Coloboma of Iris?

• Coloboma occurs due to a defect in the formation of the eye. The formation of the eye occurs during the second month of intrauterine life. The complete formation of the eye occurs when the fusion of two optic fissures occurs. If this fissure fails to fuse, it may cause a condition called coloboma.

• This failure to fuse can be due to any genetic or chromosomal abnormality. At times it can even occur due to environmental factors such as the consumption of alcohol during pregnancy.

• Colobomas might happen as a piece of a hereditary disorder. It is a distinctive component of a hereditary disorder called CHARGE, an abbreviation for:

C- Coloboma of the eye.

H- Heart defects.

A- Atresia of choanae.

R- Retardation of growth and development.

G- Genital abnormalities.

E- Ear abnormalities.

Can Coloboma Be Inherited From Parents?

Coloboma of the iris has a mixed pattern of inheritance. Sometimes it is observed as an autosomal dominant pattern, whereas sometimes as a recessive pattern. However, if both the affected child's parents have this condition, there is a higher chance of occurrence.

Can Coloboma Be Associated With Other Conditions?

Coloboma of the iris is found to co-occur with other conditions, such as :

1. Cataract (clouding of the cornea).

2. Glaucoma (increased pressure in the eye).

3. Heterochromia (different eye colors in both eyes).

4. Nystagmus (involuntary movement of the eye).

5. Any refractive errors such as nearsightedness or farsightedness.

6. Poor visual field.

7. Retinal detachments.

How to Diagnose a Coloboma?

An ophthalmologist will do a detailed examination in order to determine the vision. This also aids in determining if there is any vision loss. The various tests that can be done are:

1. Ophthalmoscopy: It can be direct or indirect. This helps to visualize the eye structures, such as the cornea and the retina. Any defects can be seen here.

2. Slit Lamp Examination: This helps to visualize if there is any defect in the anterior segment of the eye.

3. Optical Coherence Tomography: This is an advanced form of investigation.

4. CT (Computed Tomography) or MRI (Magnetic Resonance Imaging) Scan: This is an additional investigation that could be done to check if there is any involvement of the brain and its associated structures.

How to Treat the Coloboma of the Iris?

Since coloboma of the iris is a defect in itself, its treatment largely aims at giving additional support such as:

1. Usage of spectacle to have a full vision. Since this defect may be associated with partial vision, a spectacle can be prescribed to have optimal vision.

2. Using contact lenses for cosmetic purposes. Lenses can aid in covering the defect, improving the appearance of the person affected by it.

3. Treatment of other associated conditions such as cataracts and glaucoma.

Conclusion:

Since coloboma is a defect of the eye that has been present since birth, it does not have any definitive treatment. It largely involves the management of the condition through cosmetic ways and addressing its associated conditions. However, coloboma that occurs due to environmental factors such as consumption of alcohol during pregnancy can be prevented if necessary precautions are taken.