1. Optics and Refractive errors correction By Dr. ABDULMAJID ALSHEHAH Ophthalmology consultant Anterior Segment and Uveitis consultant

2. Contents Basic optics. Refractive power of the eye. Refractive status of the eye. Refractive errors. Eyeglasses. Contact lenses. Refractive surgery. Visual aids.

3. Basic optics

4. Light In physics, the term light refers to electromagnetic radiation of any wavelength, whether visible or not.

5. Light Visible light (commonly referred to simply as light) is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has a wavelength in the range of about 380 nanometres (nm), or 380×10−9 m, to about 740 nanometres – between the invisible infrared, with longer wavelengths and the invisible ultraviolet, with shorter wavelengths

6. Lenses

8. Refractive power of the eye

9. Refractive status of the eye. Emmetropia Refractive state of the eye when parallel rays of light from a distant object are brought to focus on the retina with the eye at rest (i.e. not accommodating) When out of focus on the retina : Ametropia

10. Refractive errors (Ametropia) Myopia (nearsightedness or shortsightedness ) Hyperopia (hypermetropia,farsightedness or; longsightedness)

11. Astigmatism

13. Presbyopia

14. Presbyopia correction Glasses Bifocal if ametropic Surgery include corneal and lens exchange procedures but still patient satisfaction is not encouraging

15. Corrective lenses Spherical lensesCylindrical lenses

16. Glasses prescription

17. Eye glasses

18. Limitation Cosmetic Discomfort. Limited clear visual field. Sports Magnification and minification High Astigmatism correction Complications Almost None

19. Contact lenses CorrectiveCosmetic

20. Contact lenses Limitation Expensive Daily care Allergy Complications Infection Corneal ischemia Corneal thinning

21. Corneal Refractive surgery LASIK Laser In-Situ Keratomileusis LASEK Laser sup-epithelial Keratomileusis EPI-LASIK Epithelial Laser In-Situ Keratomileusis. INTRALSE-LASIK (Femto-LASIK)

23. Corneal Refractive surgery Limitation High refractive errors Keratoconus patients (clinical and subclinical) Complications Infection Scarring Dryness Residual error Overcorrection

24. Non-Corneal Refractive surgery Phakic intraocular lens insertion Clear lens extraction Cataract surgery.

26. Vision Aids

27. Questions