Refractive errors and how to correct them
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This document summarizes different types of refractive errors and how they are corrected. It discusses emmetropia as the normal eye condition and ametropia as a refractive error where light rays do not focus on the retina. The main types of ametropia covered are hyperopia, myopia, and astigmatism. For each type, it describes the optical cause, symptoms, and common treatment options like glasses, contact lenses, or surgery. Presbyopia and aphakia, which are also refractive errors related to the aging eye and lens removal, are briefly covered as well. Overall, the document provides an overview of common vision conditions and how they impact vision and are typically addressed.
Refractive errors and how to correct them
- 1. REFRACTIVE ERRORS AND HOW TO CORRECT THEM Dr Solanki Optometry Department
- 2. Refractive Errors Emmetropia Ametropia A. Hyperopia B. Myopia C. Astigmatism Presbyopia Aphakia
- 3. Emmetropia The emmetropic eye is normal eye Emmetropic eye parallel rays of light come to focus on the retina
- 4. Ametropia Ametropia (Refractive error) Mismatch between axial length and refractive power Parallel light rays don’t fall on the retina (no accommodation) Hyperopia { hypermetropia } Myopia Astigmatism
- 5. Hyperopia {Hypermetropia} The parallel rays coming from infinity focus at point behind the retina( unaccommodative eye) Axial hyperopia Curvature hyperopia Latent hyperopia Manifest hyperopia Absolute hyperopia
- 6. To Understand A 32 year old man have vn of 6/18 With+ 1.00 D improves vn 6/6(Absolute hyperopia) If an additional+1.50D patient can still see 6/6 (manifest hyperopia) With cycloplegic +3.50D vn 6/6 So 1.00D is latent
- 7. Symptoms and treatment Young may not cause symptoms Eye strain Headaches Earlier presbyopia On demand to correct with convex lenses Spectacle Contact lens Surgery
- 8. Myopia Is near-sightedness is that condition on in which parallel rays of light come to focus at point just in front of the retina Axial myopia Curvature myopia Index myopia
- 9. Symptoms And Treatment Inability to see objects clearly at distance Squeeze eyes Burning sensation To correct with concave lens Spectacle Contact lens Surgery
- 10. Astigmatism Astigmatism is the condition in which rays of light are not refracted equally in all directions so that point focus on the retina is not attained Regular astigmatism Irregular astigmatism
- 11. Regular Astigmatism Regular astigmatism is that refractive condition in which the axes of the principal meridians of the astigmatism are right angles to each other. Types: • Simple Astigmatism • Simple Hyperopic / Myopia Astigmatism • Compound Hyperopic / Myopic Astigmatism • Mixed Astigmatism
- 13. Irregular Astigmatism It is a refractive condition in which excess of the principal meridian are not right angle to each other. If the cornea has damaged by Trauma or inflammation or scar tissue. Irregularity of the corneal surface.
- 14. Symptoms and treatment Blurred vision Eye strain To correct with concave/convex cyl Spectacle Contact lens Surgery
- 15. Presbyopia Everyone becomes presbyopic with age Decreases accommodative ability of the ciliary muscle
- 16. Symptoms and treatment Inability to do near work Some patient complain that they have to hold the print farther away Fatigue Trouble with Threading a needle To correct with convex lens Spectacle Contact lens
- 17. Visual Age consideration for Presbyopic At the ages 42 to 45----+1.00D to +1.25D At the ages 45 to 50----+1.50D to +1.75D At the ages 50to 65----+2.00D to +3.00D
- 18. Aphakia Is a condition in which the crystalline lensis absent from the eye May be caused by removal of cataract lens or displacement of the lens To correct with convex lens Spectacle Contact lens Surgery
- 19. Kept in mind The optical centers must be exact Vertex distance Lanticular aphakic lens The frame must fit comfortably on the nose and to b set straight
- 20. THANK YOU