Page 5 - NAME OF CONDITION: REFRACTIVE ERRORS

keratoplasty, radial keratotomy (RK), complicated refractive surgery), the magnitude and

the axis of astigmatism vary from point to point across the entrance pupil.
In addition to these refractive errors, there is another condition called as presbyopia which
occurs in all people, usually above the age of 40 years.

Presbyopia
In this condition,the eye is unable to focus near objects. The problem in presbyopia is the
aging of the lens and the accommodating system, which fail to focus near objects on the
retina. Although not truly a refractive error, presbyopia will be considered in this document
because its correction has similarities to the correction of refractive errors.

II. INCIDENCE OF THE CONDITION IN OUR COUNTRY

With blindness defined as presenting distance visual acuity <3/60 in the better eye, the
prevalence of blindness due to refractive error has been reported to be as high as 0.2% in
India, for all age groups in the population considered together. A recent survey shows an
increase in the incidence of refractive errors as a cause of social blindness from 12% to
15%, whereas the burden of cataract has actually decreased from 80% to 62% (Source:
National Survey of Blindness 1986-89 and 2001-02).

III. DIFFERENTIAL DIAGNOSIS:

Patients with refractive errors often complain of defective vision, tiredness of eyes and
headache. Even though refractive errors is the most common causative factor for defective
vision, other organic causes such as the following should be examined and ruled out by a
comprehensive eye examination.
i. Cataract
ii. Retinal disorders
iii. Optic nerve pathology

iv. Glaucoma
v. Other media opacities
It should be once again emphasized that estimation of refractive errors should be a part of
a complete ophthalmic evaluation. In addition, other causes of headache like sinusitis or
migraine should be suspected especially when there are complaints of recurrent headache
in the setting of a normal refractive status.

IV. PREVENTION AND COUNSELING

For all practical purposes, there are no strategies which are effective in preventing this
condition from occurring. However, counseling on the importance and compliance to

treatment optimizes visual performance and prevents further deterioration of the
functioning of the eye. Most myopic refractive errors develop and progress during
childhood and adolescence, which corresponds to their general physical development. The
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