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Refractory errors
1. Mr. Manikandan.T,
RN., RM., M.Sc(N)., D.C.A .,(Ph.D)
Assistant Professor,
Dept. of Medical Surgical Nursing,
VMCON, Puducherry.
2. • In refractive errors, vision is impaired because
a shortened or elongated eyeball prevents
light rays from focusing sharply on the retina.
• Shape of the eye does not bend correctly,
resulting in blurred image.
3. • Myopia : Nearsightedness (parallel rays of light
coming from infinity are focused in front of
retina)
• Hyperopia : Farsightedness(parallel rays of light
coming from infinity are focused behind retina)
• Presbyopia: loss of near vision with age
• Astigmatism: front surface of the eye or the lens
inside the eye is curved differently in one
direction than the other.(near and long
sightedness)
10. • Photo Refractive Keratotomy (PRK): A layer of cornea tissue is
removed with laser, which flattens cornea and allows light
rays to focus on retina
• Ortho keratology (Keratomileusis): special contact lenses must
be worn that slowly reshapes the cornea to correct myopia
11. Cont.,
• LASIK(Laser Assisted In situ Kerato-mileusis): this procedure
used to treat near and farsightedness. A laser is used to
reshape the cornea by making a flap in surface of cornea or
removing upper layer of cornea.
• Automatic Lame – LLAR keratoplasty (ALK): abnormal corneal
tissue is replaced by health donor
12. Cont.,
• Laser Assisted Sub Epithelial Keratomileusis(LASEK): A laser is
used to remove the epithelial layer of eye.
• Refractive IOL : implantation of small plastic lens after removal
of natural lens to correct myopia & Presbyopia
• Phakic IOL: implant the lens over natural lens to correct myopia
& hyperopia