Palpebral fissure

Diagram of the human eye, showing the palpebral fissure.

The palpebral fissure is the anatomical term for the opening between the eyelids. It is a key feature in the human eye and plays a crucial role in vision and ocular health. The size and shape of the palpebral fissure can vary significantly among individuals and can be influenced by genetic, developmental, and environmental factors.

Anatomy

The palpebral fissure is bordered by the upper and lower eyelids. The upper eyelid is more mobile and is responsible for covering the eye when closed. The lower eyelid is relatively stationary. The fissure itself is a horizontal slit that allows light to enter the eye, enabling vision.

The dimensions of the palpebral fissure are clinically significant. The average width of the fissure in adults is approximately 27-30 mm, while the height is about 8-11 mm. These measurements can vary based on ethnicity, age, and gender.

Function

The primary function of the palpebral fissure is to protect the eye. It acts as a barrier against foreign particles, excessive light, and injury. The eyelids, which form the boundaries of the fissure, help in spreading the tear film across the surface of the eye, keeping it moist and free from debris.

The palpebral fissure also plays a role in facial expression. Movements of the eyelids, such as blinking and winking, are important for non-verbal communication.

Clinical Significance

Abnormalities in the size or shape of the palpebral fissure can be indicative of various medical conditions. For example, a narrow palpebral fissure may be seen in blepharophimosis, while a wide fissure can be a feature of Graves' disease.

In Down syndrome, the palpebral fissures are often slanted upwards, which is a characteristic feature of the condition. Similarly, in Fetal Alcohol Syndrome, the fissures may appear shorter than average.

Related Pages

• Eyelid
• Human eye
• Vision
• Graves' disease
• Down syndrome