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56 Ophthalmic Lenses

3. Reducing the vertex distance may also result in minimizing the effect
of chromatic aberration.
4. Anti-reflection coating with consumer education may also be tried to
minimize the effect of chromatic aberration.
5. The best solution is the Achromatic lens system. The achromatic lens
uses two different lens materials – one has a regular focal length and
the other corrects the dispersion of the first lens. For this purpose one
lens is made of crown glass, i.e. low dispersion, while the other is made
of flint glass, i.e. high dispersion. The crown lens concentrates on optical
effect and introduces some dispersion and the flint glass aims at
balancing this dispersion while having least possible optical influence
on the lens function.

Fig. 6.3: Achromatic lens system

Ocular Chromatic Aberration

Fig. 6.4: Far point of an individuals focus varies with the wavelength of light