Forms of lenses (Faheem Kv)

Forms of opthalmic lenses in daily practice.

1. FORMS OF LENSES FAHEEM KV OPTOMETRY RGUHS

2.   بِسْمِ اللهِ الرَّحْمٰنِ الرَّحِيْمِ

3. 1) Convex lenses (Plus lens) a) Equiconvex b)Biconvex c) Planoconvex 2) Concave lenses (Minus lens) a) Equiconcave b)Biconcave c) Planocancave 3) Periscopic lens 4) Meniscus lens

4. 1) Convex lens a) Equiconvex lens Positive f ocal power of the lens is divided equally in each surface is called equiconvex lenses. eg : both surface having +2.00D both surface having +3.00D

5. b) Biconvex lens Both surface of the lens is in convex form but not in equal power always. eg : one surface having +3.00D and other surface having +2.00D

6. c) Planoconvex lens The back surface of the lens is plano or zero power. But all the positive power is produced by the front surface. this form of lenses are called as Planoconvex lenses. eg : One s urface having +2.00D and other surface having power zero.

7. 2) Concave lenses a) Equiconcave lens Negative focal power of the lens is divided equally in each surface is called equiconcave lens. eg : Both surface having -2.00D Both surface having -2.50D

8. b) Biconcave lens Both surface of the lens is in concave form but not in equal power always. eg : one surface having -2.00D and other surface having -1.00D.

9. c) Planoconcave lens The back surface of the lens is plane or zero power. But, all the negative power is produced from front surface. This form of lenses are called as Planoconcave lenses. eg : one surface having -2.00D and other surface having zero power.

10. 3) Periscopic lens In this lenses, one surface of the lens having positive power and the other surface having negative power. This lens having a base curve of (+or-)1.25D.

11. 4) Meniscus lens One surface of the lens having positive power and the other surface having negative power . This lenses are similar to periscopic lenses, but this lens having a base curve of (+or- )6.00D .

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