Vinay Dinakaran Mallepudi


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Code(Credit) : ABC01(1-1-0)

Course Objectives

This course deals with understanding the theory behind spectacle lenses and frames, their materials, types, advantages and disadvantages, calculations involved, when and how to prescribe. It will impart construction, design application and development of lenses, particularly of the methods of calculating their power and effect. 

Learning Outcomes

  • Measurement of lens power, lens centration using conventional techniques
  • Transposition of various types of lenses •Knowledge to identify different forms of lenses (equi- convex, planoconvex, periscopic, etc.)
  • Knowledge to select the tool power for grinding process.
  • Measurement of surface powers using lens measure.
  • Method of laying off the lens for glazing process.
  • Ophthalmic prism knowledge –effects, units, base-apex notation, compounding and resolving prisms.

Course Syllabus

Module-I (6 hrs)


Introduction – Light, Mirror, Reflection, Refraction and Absorption.


Module-II (9 hrs)


Prisms – Definition, properties, Refraction through prisms, Thickness difference, Base-apex notation, uses, nomenclature and units, Sign Conventions, Fresnel’s prisms, rotary prims



Module-III (9hrs)


Lens: Definition, units, terminology. Introduction to spectacle lenses, forms of lenses, Spherical, cylindrical and Spherocylindrical lenses, Vertex distance and vertex power, Effectivity calculations


Module IV (8 hours)


Transpositions – Simple, Toric and Spherical equivalent,

The prismatic effect, centration, decentration and Prentice rule, Prismatic effect of Plano-cylinder and sphero-cylinder lenses.


Module-V (9 hrs)


Spherometer& Sag formula, Edge thickness calculations, Magnification in high plus lenses,

Minification in high minus lenses


Module VI ( 6 hrs)


Tilt induced power in spectacles.


Module-VII (9 hrs)

Aberration in Ophthalmic Lenses


Text Books:


  1. Clinical Optics: T E Fannin& T Grosvenor, 2nd edition
  2. JALIE: Principles of Ophthalmic Lenses, Edn. 3, 1994.


Reference Books:


  1. CLIFFORD W BROOKS & IRVIN M BORISH: System for Ophthalmic Dispensing

Session Plan

Session 1

Introduction – Light, Mirror, Reflection, Refraction and Absorption.

Session 2

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