Page 9 - NAME OF CONDITION: REFRACTIVE ERRORS

C) Treatment:

Spectacle Correction:

1. Myopia: Full correction can be given to patients who are having visually demanding
activities so that they can have a good distance vision. Over correcting myopic patients
will cause excessive accommodation, which may create symptoms. Some patients may
become symptomatic from increasing myopia at low levels of illumination. These
patients may require increased correction for clear vision at night.

2. Hypermetropia: Slight under correction may be desirable in young and middle aged
hypermetropes because there is some physiological accommodative tone. With the
onset of presbyopia as the patient ages, full correction may be necessary to minimize
difficulties with near vision.

3. Astigmatism: Full correction may not be needed for individuals with regular
astigmatisms. Adults with astigmatism may not accept full cylindrical correction in their
first pair of spectacles, or in subsequent spectacles if their astigmatism has been only
partially corrected or its oblique axis astigmatism.
4. Presbyopia: In presbyopic patients, accommodative amplitudes are measured to

determine if the available accommodation is sufficient for the near task. It is suggested
that half of the accommodative amplitude be held in reserve for comfort. Individuals
with myopia must exert more accommodative effort when using contact lenses, or after
refractive surgery, than when using eyeglasses. Individuals with hyperopia must exert
more accommodative effort when using eyeglasses than contact lenses.
A brief note of the basics of spectacle fitting is given below:

Frames
The types of frames can be broadly classified into Metal and Plastic Frames.

Metal Frames
Alloys of varying constituents and consistencies are used to make frames. The most
commonly used Nickel alloys, are cheap, strong and are tensile but may cause allergic
reactions in the skin and so are not advisable. Stainless steel is a good alternative as it is
inert, less allergenic and lightweight at the same time. Aluminium is lightweight but soft,

and is less allergenic. Metals such as Titanium are also becoming popular, as it is very
strong but lightweight.. The color and protective coatings given to the frame are just as
important as the base material. Electroplating is a sturdy and reliable way to coat the
frames. Cheaper frames are usually dipped or spray-painted – these coats usually peel off
fast and may not be uniform. Powder coats on frames have a longer life as the coat is fused
with the base metal. A final protective lacquer coat on top of the colour coat adds lusture
and binds the color coat to the frame.

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