Page 8 - NAME OF CONDITION: REFRACTIVE ERRORS

Verbal but preliterate child (1 to 5 year)

Preschool going children can be assessed by either of the following methods.
1. Ability to locate small objects (cake decorations).
2. Marble game test; in which child is asked to place marbles in holes of a card.
3. Illiterate E-card test.
4. Sheridan Gardiner (S-G) test.

Literate child (>5 year) and adults
These patients can be checked using a regular Snellen’s visual acuity chart. In illiterate
people, Landolt C chart or a tumbling E chart may be used. Near vision testing can be
performed using a Jeager chart.

2. Refraction:

Each eye should be evaluated independently. A dynamic refraction is done first for all
adults followed by a cycloplegic refraction if necessary. Presbyopic correction is
determined before applying dialating drops. All children, below the age of 15 years should
be refracted only after applying cycloplegics to neutralize the effects of accomadation, to
identify accomadative spasm and to diagnose strabismus of accomadative aetiology. An

objective retinoscope followed by a subjective refinement of refraction is preferred.
Distance refraction should be performed with accommodation relaxed using manifest
(noncycloplegic) refraction with fogging or other techniques to minimize accommodation
with care not to provide excess minus power correction to the patient. The common
dialating agents are tropicamide and cyclopentolate. Tropicamide provides a more rapid
onset of action and a shorter duration of effect while cyclopentolate provides greater
cycloplegia that can allow a more accurate refraction but a longer duration of effect. A
significant difference between manifest and cycloplegic refraction is frequent in children; In
adults,a substantial difference between manifest and cycloplegic refraction may require a
post-cycloplegic dynamic refraction on a subsequent day where the cycloplegic refraction

is used to guide the final manifest prescription. The post-cycloplegic refraction is
performed when full accommodation has returned.

3. Measurement of interpupillary distance (IPD) to determine the distance in
millimeters between the centre of the pupils of the two eyes for a given viewing distance
with a ruler. IPD is to be measured for both distance and near.

4. Determination of vertex distance and precise astigmatic axis is especially important

in patients with high refractive errors.

5. Determination of Muscle Balance

This is done for people complaining of asthenopic symptoms

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