Ho Optometrist

Your Local Optometrist from 怡保……Ipoh….. Perak, Malaysia

How to fit soft contact lenses

Soft contact lens fitting characteristics are essential for a correctly fitting contact lens to give complete corneal coverage with proper centration to avoid the risk of contact lens complication.

Soft contact lens fitting can be assessed in relation to lens movement with:

  • Blinking
  • Upwards and lateral gaze
  • The ‘push-up’ test

This simple ‘push-up’ test is used to assess the speed of recovery when a soft lens is displaced vertically upwards with the eye in primary position (preferably be done by your eye care practitioner). A rapid recovery movement suggests a satisfactory fitting, whereas a slow recovery may be indicative of tightness.

Appearance of a correctly soft contact lens fitting – Diagram (A) shows the limits of acceptable movement and position for soft contact lenses.

Appearance of a tightly soft contact lens fitting – Diagram (B) indicates the lack of movement.

Appearance of a loose soft contact lens fitting – Diagram (C)  shows the excessive mobility of a loose fitting

The general principles for a good fitting are:

  • Good centration.
  • Complete corneal coverage.
  • Approximately 0.5mm of vertical movement on blinking in primary position.
  • Lag of up to 1mm on upwards gaze or lateral eye movements.
  • Rapid recovery on vertical displacement (push-up test).
  • Comfortable in all direction of gaze.
  • Good visual acuity.
  • Vision remains stable on blinking.
  • No irritation.

LOOK GOOD . SEE GOOD . FEEL GOOD

P.S.  A correctly fitted soft contact lens with just 0.5mm to 1mm movement in the eye, is important to ensure long hours wearing comfort and healthier eyes. Please do not take for granted on contact lens fitting!

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New estimates of visual impairment and blindness: 2010

Global estimate of the number of people visually impaired.

The magnitude of visual impairment and blindness and their causes have been estimated, globally and by WHO region from recent data. For countries without data estimates were based on newly developed model. Globally the number of people of all ages visually impaired is estimated to be 285 million, of whom 39 million are blind. People 50 years and older are 82% of all blind. The major causes of visual impairment are uncorrected refractive errors (43%) and cataract (33%); the first cause of blindness is cataract (51%). Visual impairment in 2010 is a major global health issue: the preventable causes are as high as 80% of the total global burden.

Ref: Pascolini D, Mariotti SPM. Global estimates of visual impairment: 2010. British Journal Ophthalmology Online First published December 1, 2011 as 10.1136/bjophthalmol-2011-300539.

http://www.who.int/blindness/en/index.html

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