Physiology of Vision

Introduction

Vision is one of the most crucial senses that allows humans to perceive their surroundings. The eye works as an optical system, transmitting signals to the brain for processing.

Anatomy of the Eye

• Cornea: The transparent front part that refracts light.
• Iris: Controls the amount of light entering the eye.
• Lens: Adjusts focus for near and distant objects.
• Retina: Contains photoreceptor cells that convert light into neural signals.
• Optic Nerve: Transmits signals to the brain.

How Vision Works

Light passes through the cornea and lens, focusing on the retina. Photoreceptor cells, rods and cones, convert light into electrical impulses, which travel through the optic nerve to the brain.

Common Physiological Disorders of Vision

Refractive Errors

These occur when light does not focus directly on the retina, leading to blurred vision.

• Myopia (Nearsightedness): Difficulty seeing distant objects.
• Hyperopia (Farsightedness): Difficulty seeing close objects.
• Astigmatism: Distorted vision due to irregular corneal shape.
• Presbyopia: Age-related difficulty focusing on near objects.

Cataracts

Clouding of the lens leading to vision impairment, commonly associated with aging.

Glaucoma

Increased intraocular pressure damaging the optic nerve, potentially leading to blindness.

Macular Degeneration

Affecting the central retina, causing vision loss over time.

Diabetic Retinopathy

Retinal damage due to prolonged diabetes, affecting blood vessels and vision.

Conclusion

Understanding the physiology of vision helps diagnose and manage common eye disorders effectively. Regular eye exams are essential to maintaining good vision health.