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The Importance of Screening for Visual Impairment


The prevalence of visual impairment increases as the population aged. Visual impairment includes low vision and blindness.

Blindness is defined as visual acuity of less than 3/60 or inability to count fingers at a distance of 3 meter in the better eye using available means of corrective devices (with glasses if available).

Low vision is defined as acuity of less than 6/18 but equal to or greater than 3/60 in the better eye using available means of corrective devices (with glasses if available).

National Eye Survey done in Malaysia in 1996 shows the prevalence of bilateral blindness was 0.29 % and low vision was 2.4 %. A study done in a same sub-population of a village in 1984 and 10 years later shows an increase in the prevalence of visual impairment.

The study also shows that the prevalence of blindness in children was 0.05 % and increases to 4.77 % in the elderly aged 70 years and above.

In the other hand, prevalence of low vision in children was 0.4 % and increases to 30.59 % in the elderly age 70 years and above.

What are the causes of visual impairment?

Causes of visual impairment (blindness and low vision) are as follow:.

  • Cataract
  • Retinal diseases
  • Refractive errors
  • Corneal diseases
  • Glaucoma

Why is visual screening important?

  • Visual screening is important as more than 50 % of blind people had avoidable and treatable causes.
  • More than 80 % of people with low vision had preventable or treatable causes.
  • Cataract and uncorrected refractive error remains the leading cause of visual impairment which is easily treated in Malaysia.
  • World Health Organization reported that cataract is the leading cause of low vision and as population aged, blindness caused by age- related macular degeneration increases significantly.
  • World Health Organization also reported that 82 % of blind people were within the age group  of 50 years and above.
  • Diabetic eye disease causes low vision in up to 22 % of patient and blindness in 9% of patient.

What happens if visual impairment is not detected early through visual screening and therefore not managed accordingly?

Intact vision provides information on our surrounding and environment. Impaired vision will affect the daily activities which will lead to dependency.

Unilateral visual impairment is associated with issues of safety and independent living . Patient will have difficulties in estimating depth, contrast sensitivity, glare as well as coordinating vision and motor action. These will give rise to unsteady gait.

Bilateral visual impairment is associated with dependency, psycho-social issues and impaired activities of daily living.

Visual impairment is associated with:

  • Falls and hip fracture
  • Motor vehicle accidents
  • Dependency
  • Depression and irritability
  • Self-isolation
  • Low self esteem
  • Memory loss

In addition, many of the visual problems among the elderly were not reported to medical personnel. Thus, screening for visual impairment among the elderly is recommended.


  1. K.Y Loh, J. Ogle Age Related Visual Impairment in Elderly Med J Malaysia Vol 59 No 4 Okt 2004
  2. M Zainal, SM Ismail, AR Ropilah, H Elias, G Arumugam, D Alias, J Fathilah Prevalence of blindness and low vision in Malysia population: results from the National Eye Survey 1996 Br J Ophthalmol 2002: 86: 951 – 956
  3. Serge Resnikoff, Donatella Pascolini, Daniel Etya’ ale Global data on visual impairment in the year 2002.Policy and Practice. Bulletin of World Health Organization 2004;82: 844 – 851
  4. HTV Vu, J.E. Keeffee, C.A. Mc Carty, H R Taylor. Impact of unilateral and bilateral vision loss on quality of life. Br J Ophthalmol. 2005 March; 89(3): 360–363.
Last Review : 16 July 2013
Writer : Dr. Radziah bt. Abd. Rashid