Knowledge Base for Patients

Anatomy of the Eye​

Sclera

The thick, white outer wall of the eye. Commonly knows as the ‘whites’ of the eye.

Iris

The colored ring of tissues suspended behind the cornea and immediately in front of the eye lens; regulates the amount of light entering the eye by adjusting the size of pupil.

Cornea

The outer, transparent, dome-like structure that covers the iris, pupil and anterior chamber and it is a part of the eye’s focusing system.

Pupil

The iris has a small opening or aperture in the center called the Pupil, which dilates and constricts according to the external light.

Lens

The lens is a flexible, transparent structure that changes shape to focus images on the retina. The lens is suspended behind the iris by the zonular fibers.

Vitreous

The vitreous body is the large area between the lens and the retina. The vitreous body is filled with a viscous, clear jelly (the vitreous humor), which supports and protects the lens and the retina.

Choroid

Vascular layer beneath the retina. It nourishes the outer portion of the retina.

Optic Nerve

The bundle of over one million nerve fibers that carries visual message from the retina to the brain.

Macula

The oval yellow sensitive spot near the centre of the retina; provides vision for the work and reading.

Retina

The light – sensitive layer of tissues that lays at the back of the eyeball; and it sends visual message through the optic nerve to the brain.


How Eye Works


Light rays pass through the cornea, which focus them.

The pupil in the iris expands (in dark) and contracts (in bright) depending upon the light condition.

The lens fine-tunes the focusing.

The image lands on the retina, a complex system of nerve cells, which converts light into impulses. Are these impulses then sent to the brain via optic nerve.

The brain interprets these impulses and converts impulses into color image.

The eye is strong and remarkably adaptable, but being an organic mechanism, it does not work perfectly. The eye is especially prone to slight irregularities and requires glasses to see more clearly.


Myopia (Nearearsightedness)

Myopia Explained

Myopia, also known as nearsightedness, is a condition in which a person can see near objects more clearly than distant objects. Myopia usually occurs when an eyeball is larger than normal. Due to the larger eyeball, light rays from distant objects focus in front of the retina. The result is blurred vision. Mainly myopia is inherited. Frequent or prolonged near work may influence its progression. It is typically detected in school-age children, which may worsen during adolescence, and generally stabilizes between the age of 20 to 40 years.

Light entering the eye is focused in front of the Retina. It is caused by a steeper than normal Cornea, or an eye that is longer than normal.


Hyperopia (Farsightedness)

Hyperopia Explained

Hyperopia, also known as farsightedness, is a condition in which a person can see distant objects more clearly than near objects. Hyperopia usually occurs when an eyeball is smaller than normal. Due to the smaller eyeball, light rays from near objects focus at the back of the retina. The result is blurred vision. Mainly hyperopia is inherited. As the young children tend to be slightly hyperopic. As the eye grows, eyeball becomes longer and hyperopic eventually lessens.Presbyopia, a condition with similar symptoms, has an entirely, has an entirely different cause and is related to ageing.

Light entering the eye is focused behind the Retina. It is caused by a flatter than normal Cornea, or an eye that is shorter than normal


Astigmatism

Astigmatism Explained

Astigmatism is a condition in which objects, both near and distant, appear same as in a funhouse mirror at an amusement park.The cornea and lens of the eye become spherical. When one or both are curved more steeply in onemeridian than another, it results into different surface powers at different meridians of the cornea or the lens.
Thisuneven curvature prevents light rays to focus on single point of the retina.

Astigmatism often occurs in combinations with myopia and hyperopia.

A person with Astigmatism has a cornea that is shaped more like a football than a sphere. It usually has a steeper slopeand a flatter slope, resulting in light rays being focused in two parts of the eye. This causes blurry vision and can be seen in Myopic or Hyperopic people.


Presbyopia

Presbyopia Explained

After approximately 40 years of age, most people find it increasingly difficult to see the near objects. This condition is known as Presbyopia and is a normal part of ageing. It develops as the lens of the eye becomes less flexible. Presbyopia should not be confused with by hyperopia or farsightedness, which is related to the size of eyeball.


Cataract

Cataract Explained

A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are develop as a result of ageing, metabolic disorders, trauma or heredity depending upon its size and location. Due to cataract, part of the lens becomesopaque, light does not pass through easily and the patient’s vision becomes blurry – like looking through cloudy water or a fogged-up window.

​If a part of the lens becomes opaque, light does not pass through easily and the patient’s vision becomes blurry – like looking through cloudy water or a fogged-up window.

Cataract Symptoms

- Difficulty to see at night
- Seeing halos around lights
- Loss of color intensity
- Cloudy, fuzzy, foggy, or filmy vision
- Frequent changes in eyeglass diopters
- Sensitivity to glare from the sun, lamps and especially while driving at night
- Double vision in one eye
- Decreased contrast sensitivity (the ability to see shades, or shapes against a background)


Macular Degeneration

Macular Degeneration Explained



Macular Degeneration is a group of conditions which may cause vision loss in the macula, the small region of the retina, which sharpen the vision. There are two basic forms of macular degeneration namely dry form and wet form. 90 % of people with macular degeneration have the dry or atrophic form. If an ophthalmologist suspects that you may have macular degeneration, he/she will want to take a picture of the retina. Additionally, the doctor may need to perform another procedure called Fluorescein Angiography to see if any blood vessels are leaking into the retina. This procedure is relatively simple and not painful and is usually performed at doctor’s office.

Sometimes, laser treatment can be used to slow the progression of this condition by sealing off these growing, bleeding vessels. Although laser surgery rarely improves vision in people with neovascularization, it may slow or prevent further damage to the retina. People with wet macular degeneration in one eye have a 10% chance of developing it in their other eye. It is extremely important for people with this condition to check their eyes often, even daily with the doctor grid. You should notify your eye doctor immediately about any changes in your vision.

Someone with wet macular degeneration might see wavy lines and dark areas on the Amsler grid.

Fortunately dry macular degeneration rarely results in the loss of peripheral vision.

Symptoms​

- You may experience blank spots within your field of vision. These spots will follow your eye movements.
- Straight lines may appear distorted or wavy. The wavy lines will follow your eye movements.


Glaucoma

Glaucoma Explained


Glaucoma occurs as a result of increased intraocular pressure caused by a malformation or malfunction of the eyes drainage system. This increases pressure on the optic nerve, and causes progressive, permanent loss of eyesight if left untreated.

Open Angle Glaucoma is caused when the normal drainage system of the eye becomes partially blocked and causes pressure to build within the eye.

Pressure builds when the drainage system is blocked. This increasing pressure presses against the Optic Nerve and causes a loss of sight. ​

Symptoms

- In the very early stages there are NO symptoms.
- Mild pain in the eye increases gradually over time
- “Halos” appearing around lights.
- Gradual loss of Peripheral vision
- Loss of night vision.