Refractive Errors

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1. REFRACTIVE ERROR MR. MOUNESH. D. BADIGER SENIOR TUTOR DEPARTMENT MEDICAL SURGICAL NURSING KAHER INSTITUTE OF NURSING SCIENCES, BELAGAVI. 31 August 2020 1 MOUNESH

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3. REFRACTION OF LIGHT 31 August 2020 3 MOUNESH

4. DEFINITION Refractive error also is problem with focusing of light on the retina . The lens is also known as the aquula (Latin, a little stream, dim. of aqua, water) or crystalline lens. Refractive error means that the shape of the eye does not bend light proper and correct resulting in a blurred image . 31 August 2020 4 MOUNESH

5. EMMETROPIA : No optical correction is needed because the eye is naturally in optimal focus. AMETROPIA: Corrective lenses are necessary to bring the eye to a state of optimal focus. 31 August 2020 5 MOUNESH

6. TYPES OF AMETROPIA Myopia or nearsightedness Hyperopia or farsightedness Astigmatism Presbyopia 31 August 2020 6 MOUNESH

7. MYOPIA Near-sightedness also known as short – sightedness and 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. 31 August 2020 7 MOUNESH

8. HYPEROPIA Hyperopia or hypermetropia is caused by an eyeball that is shorter than normal or from a cornea that is less curved than normal. 31 August 2020 8 MOUNESH

9. ASTIGMATISM It is a condition in which an abnormal curvature of the cornea is not perfectly spheric. Cornea cannot bend the rays of light equally in all direction, and images are not properly focused. 31 August 2020 9 MOUNESH

10. PRESBYOPIA Presbyopia is the gradual loss of eyes' ability to focus on nearby objects (loss of near vision with age) difficulty in reading or seeing at arm's length. It's a natural, often annoying part of aging. Presbyopia usually becomes noticeable in early to mid-40s and continues to worsen until around age 65. 31 August 2020 MOUNESH 10

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12. ETIOLOGICAL FACTORS Infection Injury due to optic nerve damage Ultraviolet radiation Eye disease Inherited ( Aphakia ) 31 August 2020 12 MOUNESH

13. Aging ( above 45 year ) Environmental factors Previous corneal injury Previous eye surgery Optic nerve hypoplasia (Congenital disorrder of optic nerve , underdevelopment) 31 August 2020 13 MOUNESH

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15. CLINICAL MANIFESTATIONS Double vision Haziness (unclearness) Glare or halos around bright light Squinting (it is a condition where the eyes do not look in the same direction ) 31 August 2020 15 MOUNESH

16. Headaches Eye strain fatigue pain in or around the eyes Blurred vision Eye irritation 31 August 2020 16 MOUNESH

17. PATHOPHYSIOLOGY Due to etiology factors such as infection Degenerative changes causes by gradual loss of elasticity of lens Which leads to decreased ability to accommodate (lens changing its shape) Lead to refractive errors 31 August 2020 17 MOUNESH

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19. DIAGNOSTIC EVALUATIONS History collection Physical examination Corneal topography:  It is a computer assisted diagnostic tool that creates a three-dimensional map of the surface curvature of the cornea. 31 August 2020 19 MOUNESH

20. Slit lamp exam Snellen chart examination Ophthalmoscope Retinoscopy 31 August 2020 20 MOUNESH

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22. MEDICAL MANAGEMENT Cycloplegic : drugs are used to refraction ( to paralyze the ciliary muscle in order to determine the true refractive error of eye ) Cholinergics ( Miotics ): - It increases aqueous fluid outflow by contracting the ciliary muscles. E.g. Pilocarpine , Carbachol Analgesic eye drops 31 August 2020 22 MOUNESH

23. Beta blockers : Betaxolol , Timolol Antibiotic eye drops 31 August 2020 23 MOUNESH

24. CORRECTIVE LENSES Myopia- concave or minus lenses 31 August 2020 24 MOUNESH

25. Hyperopia - convex or plus lenses 31 August 2020 25 MOUNESH

26. Astigmatism- Toric lenses 31 August 2020 26 MOUNESH

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30. LASIK-LASER EYE SURGERY ( LASER ASSISTED IN SITU KERETO-MILEUSIS )  A kind of laser eye surgery designed to change the shape of the cornea to eliminate or reduce the need for glasses and contact lenses in cases of severe myopia (nearsightedness) 31 August 2020 30 MOUNESH

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32. KERATOMILEUSIS It is a method of reshaping the cornea surface to change its optical power. 31 August 2020 32 MOUNESH

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34. AUTOMATIC LAME -LLAR KERATOPLASTY (ALK) Keratoplasty is the procedure where by abnormal corneal tissue is replaced by a healthy donor cornea. 31 August 2020 34 MOUNESH

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36. PREVENTIVE MEASURES Identify the cause & eliminate the cause Lens correction – a concave lens is used to correct the problem Prevention foreign particles enter in eye Use of sunglasses Use of antibiotics prevention from infection 31 August 2020 36 MOUNESH

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