REFRECTIVE ERRORS.pptx refraction errors
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Refractive errors occur when the eye's shape prevents light from focusing sharply on the retina, leading to blurred vision, which can be corrected with eyeglasses, contact lenses, or surgical procedures. Common types of refractive errors include myopia, hypermetropia, astigmatism, and presbyopia, each requiring different correction methods. Diagnosis involves various assessments such as corneal topography and tonometry, while management encompasses both non-invasive and surgical options.
REFRECTIVE ERRORS.pptx refraction errors
- 2. REFRACTIVE ERRORS • Refraction results in the focusing of image on the retina of the eye, permitting vision. • In refractive errors, vision is impaired because a shortened or elongated eyeball prevents light rays from focusing sharply on the retina. • Blurred vision from refractive errors can be corrected with eyeglasses or contact lenses.
- 3. Refraction • Refraction is the bending of light as it passes through one object to another. • Vision occurs when light rays are bent (refracted) as they pass through the cornea and the lens. • The light is then focused on the retina. The retina converts the light-rays into messages that are sent through the optic nerve to the brain. • The brain interprets these messages into the images we see.
- 4. TERMS 1. Emetropia (optically normal eye) can be defined as a state of refraction, when the parallel rays of light coming from infinity are focused at the sensitive layer of retina. 2. Ametropia (a condition of refractive error) is defined as a state of refraction, when the parallel rays of light coming from infinity are focused either in front or behind the sensitive layer of retina.
- 5. Sign and Symptoms 1. Blurred vision 2. Double vision 3. Haziness (uncleared) 4. Glare or halos around bright lights 5. Squinting 6. Headaches 7. Eye pain 8. Eye strain
- 6. Etiology/ Risk factors 1. Genetics 2. Marfan syndrome 3. Environmental factors 4. Reading for long time 5. Socioeconomic status 6. Higher levels of education
- 7. Types of refractive errors: 1. Myopia 2. Hypermetropia (Hyperopia) 3. Astigmatism 4. Presbyopia
- 8. 1. Myopia • Near-sightedness • Problem seeing objects far away • Distance between lens and retina too large • Light focused in front of retina • Correct with concave (diverging) lenses
- 9. 2. Hypermetropia • Far-sightedness • Problem seeing close objects • Distance between lens and retina too small • Light focused behind retina • Corrected with convex (converging) lenses
- 10. 3. Astigmatism • Eye cannot focus an object’s image on a single point on retina due to abnormal shape of cornea and causes blurred vision • Some types can be corrected with cylindrical/ oval lenses
- 11. 4. Presbyopia • Presbyopia is the gradual loss of eye’s ability to focus on nearby objects. • It occurs due to hardening/ degeneration of lens due to ageing. • It usually becomes noticeable in early to mid- 40s and continues to worsen until around age 65 years. • Corrected with convex lenses
- 12. Presbyopia
- 13. Diagnostic Evaluation 1. History taking 2. Corneal topography: Assess the shape of cornea 3. Slit lamp exam: The doctor uses this microscope to shine a beam of light shaped like a small slit on effected eye. It may dilated pupils during the test it help diagnose. 4. Tonometry: This test measures the pressure inside eye which is called intra ocular pressure 5. Retinoscopy: Is a technique obtain an objective measurement of the refractive error of a patients eye.
- 14. MANAGEMENT • Refractive errors can be corrected with –Eyeglasses –Contact lenses –Surgery • Eyeglasses are the simplest and safest way to correct refractive errors.
- 15. Contact Lenses • In many cases, contact lenses provide clearer vision, a wider field of vision, and greater comfort. They are a safe and effective option if fitted and used properly.
- 16. SURGICAL MANAGEMENT 1. Keratomileusis: It is a method of reshaping the cornea surface to change its optical power. 2. LASIK- laser eye surgery: (Laser Assisted In Situ Kereto- Mileusis) ✓This procedure used to treat nearsightedness, farsightedness ✓A laser is used to reshape the cornea ✓To improve the way the eye focuses light rays onto the retina at the back of the eye.
- 17. 3. Automatic lame-llar kerato plasty (LLK) Keratoplasty is the procedure where abnormal corneal tissue is replaced by a healthy donor cornea (corneal transplant). 4. Photo Refractive Keretotomy (PRK): To correct myopia, the eye surgeon gently remove the pathological epithelial surface of corneal cells (corneal scraping).
- 18. NURSING INTERVENTIONS • Providing preoperative care. Use of anticoagulants is withheld to reduce the risk of retrobulbar hemorrhage. • Providing postoperative care. Before discharge, the patient receives verbal and written instructions about how to protect the eye, administer medications, recognize signs of complications, and obtain emergency care.