Development of Optic Vesicle and Coloboma

In this section, the development of the optic vesicle and the condition called coloboma are discussed.

Development of Optic Vesicle

• The optic vesicle develops further and is converted into the optic stalk.

• The hyaloid artery enters through invagination in the ventral part, forming the hyaloid fissure or choroid fissure.

Coloboma

• Coloboma is a condition caused by incomplete closure of the choroid fissure.

• It can result in a gap in the iris, known as coloboma iridis.

• In some cases, coloboma may extend to involve the ciliary body, retina, or even the optic nerve.

• If coloboma involves the lens, it can lead to coloboma lentis or a false gap in the lens.

• The shape of the lens may be abnormal due to missing zonular fibers.

Visual Defects in Coloboma

• Coloboma iridis usually does not cause major visual defects but may result in photosensitivity and cosmetic concerns.

• If coloboma involves the lens or retina, visual problems such as blind spots (scotomas) may occur.

• Severe problems can arise if coloboma extends towards the optic nerve.

Additional Information

• Coloboma may involve iris, ciliary body, lens (pseudo coloboma), and overlying choroid but typically does not involve sclera.

• The neural retina formed within the gap region is thin and atrophic with no retinal pigment epithelium present.

New Section The Coloboma of Eyelid

This section discusses the coloboma of the eyelid, a separate disease from the traditional type of coloboma that does not involve the eyelid. The embryological basis of this condition is not well understood, but it is believed to be related to dysfunction in the migration of neural crest cells forming the mesenchyme.

Coloboma of Eyelid

• The coloboma of the eyelid is a separate disease from the traditional type of coloboma.

• It involves a gap in the eyelid and has different embryology compared to other types.

• The exact cause and embryological basis for this condition are not properly known.

• It is believed that there may be some dysfunction in the migration of neural crest cells forming the mesenchyme.

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