Vision

Normal Vision

• light is focused directly on the retina - can see clearly both near & far

Vision & Focusing

Nearsightedness  (myopia)• caused usually by an abnormally long eye

length or sometimes by an excessively steep curvature of the cornea or lens.

• results in light rays coming into focus in front of the retina.  This results in distant objects appearing blurry, while objects near to the viewer can be seen in focus.

retina

Farsightedness (hyperopia)• is frequently caused by an abnormally short

eye length or sometimes by an excessively flat cornea or lens.

• brings distant objects into focus behind the retina.  The result of farsightedness is that objects near to the viewer appear blurry, while objects in the distance are seen more clearly.

retina

Astigmatism

• It may occur by itself or together with myopia or hyperopia. 

• Most people have at least a small degree of astigmatism.

• Images are blurry in some places while clear in others

• Occurs when the cornea and/or lens are not smoothly spherical in shape.  Most commonly the cornea is curved differently in one area than in another area…the shape could be described as “bumpy”

• Objects are not focused into a single image and vision is therefore distorted or blurry.

• Light does not focusin a single point.

Vision Corrective Measures

Glasses Contact Lenses Laser Surgery

Without correction

With correction

Concave lens

Convex lens