Human Eye and Vision Defects

The transparent, dome-shaped surface covering the front of the eye that helps focus incoming light.

The coloured part of the eye responsible for controlling the size of the pupil, regulating the amount of light entering.

The opening in the center of the iris, allowing light to pass through to the lens.

A transparent structure behind the pupil that focuses light onto the retina by changing its shape.

The inner layer at the back of the eye containing light-sensitive cells (rods and cones) that convert light into electrical signals.

Clear fluids filling the front and back chambers of the eye, providing nourishment and maintaining the eye's shape.

The nerve that carries visual information from the retina to the brain for processing.

The eye's ability to adjust and focus on objects at different distances by changing the shape of the lens.

Vision defects caused by the eye's inability to focus light correctly on the retina, leading to blurred or impaired vision.

Nearsightedness, a condition where distant objects appear blurry due to the eye's inability to focus on them properly.

The eyeball being too long or the cornea being too curved, causing light rays to focus in front of the retina.

Concave (diverging) lenses spread out light rays before they enter the eye, allowing them to focus on the retina.

Farsightedness, a condition where distant objects are clearer than close-up objects due to the eye's inability to focus on nearby objects properly.

The eyeball being too short or the cornea not being curved enough, causing light rays to focus behind the retina.

Convex (converging) lenses bend light rays inward before they enter the eye, focusing them on the retina.

An age-related vision condition where it becomes difficult to focus on close-up objects, requiring reading glasses for correction.

The lens of the eye loses its flexibility with age, making it harder to change shape for close-up focusing.

Reading glasses, bifocal lenses, or progressive lenses are used to correct presbyopia.

A transparent refracting medium bounded by at least two lateral surfaces inclined to each other at a certain angle.

The separation of white light into its spectrum of colours when passing through a prism.

Different colours of light are refracted, or bent, by different amounts due to their varying wavelengths.

Merging the separated colours (spectrum) created by a prism or similar device, resulting in the restoration of white light.

A natural optical phenomenon that occurs when sunlight is dispersed, refracted, and reflected by water droplets in the atmosphere, creating a spectrum of light in the form of a circular arc.

Sunlight is refracted, reflected, and refracted again by water droplets, producing the rainbow effect.

Refraction when one medium is Earth's atmosphere.

The apparent twinkling of stars due to fluctuations in the atmosphere's refractive index.

Atmospheric refraction causes stars to appear slightly higher than their actual position, especially near the horizon.

Planets, being closer and reflecting sunlight, do not twinkle because their light source is more stable.

Atmospheric refraction causes the Sun to be visible slightly earlier and later than its actual rise and set times.

The process by which light rays are redirected in different directions as they pass through particles in the atmosphere or another medium.

Scattering of light by tiny particles in Earth's atmosphere, such as smoke, water droplets, and dust, making these particles visible.

The scattering of blue light more effectively than longer wavelengths by air molecules and tiny particles, making the sky appear blue.

Light travels a longer path through the atmosphere during sunrise and sunset, scattering shorter wavelengths like blue, making red and orange colours dominate, giving the Sun a reddish hue.