Refractive Error PPT PDF

REFRACTIVE ERROR By: Dr. Namra Kanwal Emmetropia/Ammetropia ◦ Emmetropia ( optically normal eye) can be defined as a state of refraction, when the parallel rays of light coming from infinity are focusing at the sensitive layer of retina ◦ Ametropia ( a condition of refractive error), is def...

REFRACTIVE ERROR By: Dr. Namra Kanwal Emmetropia/Ammetropia ◦ Emmetropia ( optically normal eye) can be defined as a state of refraction, when the parallel rays of light coming from infinity are focusing at the sensitive layer of retina ◦ Ametropia ( a condition of refractive error), is defined as a state of refraction, when the parallel rays of light coming from infinity, are focussed either in front or behind the sensitive layer of retina. ◦ A refractive error is something about the natural shape of your eyes that makes your vision blurry. ◦ Refractive errors are a type of vision problem that makes it hard to see clearly. ◦ They happen when the shape of your eye keeps light from focusing correctly on your retina (a light-sensitive layer of tissue in the back of your eye). ◦ Refractive errors are the most common type of vision problem. Symptoms ◦ The most common symptom is blurry vision. Other symptoms include: ◦ Double vision ◦ Hazy vision ◦ Seeing a glare or halo around bright lights ◦ Squinting ◦ Headaches ◦ Eye strain (when your eyes feel tired or sore) ◦ Trouble focusing when reading or looking at a computer What causes refractive errors? ◦ Refractive errors can be caused by: ◦ Eyeball length (when the eyeball grows too long or too short) ◦ Problems with the shape of the cornea (the clear outer layer of the eye) ◦ Aging of the lens (an inner part of the eye that is normally clear and helps the eye focus) TYPES OF REFRACTIVE ERRO R ◦ The types of refractive errors are: ◦ Myopia ◦ Hyperopia ◦ Astigmatism ◦ Presbyopia  MYOPIA ◦ It is near sightedness also known as short sightedness. ◦ It is a type of refractive error in which parallel rays of light coming from infinity are focussed in front of the retina when accommodation is at rest. ◦ Myopia is a condition of the eye where light focuses in front of the retina instead of on the retina this causes distant objects to be blurred while close objects appear normal. ◦. MANAGEMENT ◦ Concave lenses in the form of glasses or contact lenses (spherical) HYPEROPIA ◦ Hypermetropia (hyperopia) or long sightedness is the refractive state of the eye where in parallel rays of light coming from infinity are focussed behind the retina with accommodation being at rest. ◦ Management: Convex lenses (Spherical) ASTIGMATISM ◦ Astigmatism is a type of refractive error where in the refraction varies in the different meridia of the eye consequently, the ray of light entering in the eye cannot converge to a point focus but form focal lines. ◦ MANAGEMENT ◦ Cylindrical lenses in the form of spectacles or contact lenses. PRESBYOPIA ◦ Presbyopia (eyesight of old age ) is not an error of refraction, but a condition of physiological insufficiency of accommodation, leading to failing vision for near.  It is usually occurs after 40 years of age. ◦ Management: Convex lenses