Ophthalmic assistant class 3 red year
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LENS IDENTIFICATION. what is convex lens , what is concave lens & what is cylindrical lens . what is myopia , what is hyperopia & what is astigmatism etc.
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Ophthalmic assistant class 3 red year
- 1. VINIT KUMAR & ARBIND RAY OPTOMETRIST,SCEH LENS IDENTIFICATION
- 2. LENS FORMS •The total power of a lens can be achieved by combining different types of curved surfaces (concave or convex) and this is called the form of lenses. •Depending up on the from lenses could be of two types: Flat Lenses and Curved Lenses •1. Both its surfaces have got same type of curvature,e.g. biconcave or biconvex
- 3. FLAT LENSES •2.One surface is flat and the power is grounded on the other surface, e.g. Plano-concave and Plano-convex. •If both surfaces are convex or both concave, the lens is biconvex or biconcave. • If one surface is Plano and the other an outward curved plus surface (i.e., a convex surface), the lens is referred to as Plano convex
- 4. FLAT LENSES • If one surface is Plano and the other curved inward for minus power (i.e., a concave surface), the lens is Planoconcave
- 5. LENSES
- 6. CURVED LENS •A lens is said to be curved when there is a convex curve on one surface and a concave curve on the other surface •Curved Lenses are of two types: Meniscus and Toric •Meniscus lenses are curved lenses where both the surfaces are spherical – anterior surface is convex and posterior surface is concave-
- 8. TORIC LENSES •Toric lenses are curved lenses where one surface is spherical and the other surface is toroidal in shape. • Toric lenses are used where a cylinder is also present in the prescription..
- 9. Lenses In order for a lens to converge light it must be thi cker near the midpoint to allow more bending. Double-con vex lens Plano-conv ex lens Converging m eniscus lens
- 10. Lenses In order for a lens to diverge light it must be thin ner near the midpoint to allow more bending. Double-conc ave lens Plano-conca ve lens diverging men iscus lens
- 11. SOME IMPORTANT QUESTION Q. Describe about lens identification? Q. Write about different forms of lenses with their uses.
- 12. THANK YOU