How The Eye Works

The eye is a hollow sphere filled with a clear, gel-like material. The front surface of the eye is a curved transparent structure called the cornea, which allows light to enter the eye. The curved clear surface bends light entering the eye to focus precisely on the retina. The retina is the inner lining of the eye which functions like photographic film in a camera. The retina processes light information which helps to form images in the brain. 

The curvature of the cornea and it's ability to bend light determines how clearly one sees. If the cornea bends light too much or in front of the retina, the condition is called myopia. If the cornea bends light too little, the condition is called hyperopia. In either case the eye will not be able to see clearly. An eye that does not bend light prescisely on the retina has a refractive error.

The cornea in nearsighted individuals (myopia) bends light too much.

 

The cornea in farsighted individuals (hyperopia) bends light too little.

Astigmatism is the condition of an eye having more than one focusing power. One meridian may have more or less than another.

 

Around the age of forty, the eye loses its ability to adjust its fine focusing power during reading; this condition is called presbyopia. Presbyopia occurs in all individuals regardless of whether they are farsighted or nearsighted.

 

Refractive surgery is eye surgery, which changes the eye’s focusing power. There are many surgical techniques which can change the eye’s focusing power, LASIK being the most popular.