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Blindness (Visual Impairment)

Introduction

Visual impairment can occur at any age and ranges from low vision to total blindness. In Malaysia prevalence of blindness for all ages is 0.2% and low vision is 2.44% (based on National Eye Survey, 1996). Prevalence of blindness among children 7 to 15 years is 0.1% (based on Refractive Error Study in Children, 2003).

Diagram of normal eye showing different parts of the eye

Disturbance of cornea, lens, vitreous, retina and optic nerve can cause visual impairment. Blindness can occur at any age and with varying degrees of impairment.

When do you consider a person is blind?

According to World Health Organization (WHO) a person is considered blind when:

  • his/her vision is worse than 3/60 in the better eye with best possible correction
  • his/her visual field is less than 10 degrees from fixation in both eyes.

Most visually impaired persons have some useful or residual vision and just because they use a cane does not necessarily mean they are totally blind.

Causes

What causes blindness?

  1. In babies and very young children;
    • Congenital abnormality e.g. congenital cataract, congenital glaucoma
    • Problems during pregnancy e.g. infection due to rubella and toxoplasmosis, alcohol consumption
    • Perinatal causes – retinopathy of prematurity
    • Eye infection – ophthalmia neonatorum
  2. In older children :
    • Refractive error
    • Amblyopia /lazy eye
    • Squint
    • Corneal scarring- infection, injury, Vitamin A deficiency
    • Hereditary diseases – albino, retinitis pigmentosa
    • Malignancy : Retinoblastoma
  3. In adults :
    • Cataract
    • Diabetic Retinopathy
    • Glaucoma
    • Age related Macular Degeneration
    • Refractive Error
    • Corneal disease : corneal infection, corneal scar due to penetrating injury, chemical burn
  4. Other causes are :
    • Eye Infection
    • Eye Injury -Penetrating, chemical burn
    • Eye Cancer – Retinoblastoma

Signs & symptoms

What are the signs of blindness?

Adults will be able to tell if they have visual problems.

Children usually do not complain. Parents, guardian and teachers need to be aware of potential eye problems and look out for :

  1. Appearance e.g. Wandering eyes, squint or white pupil
  2. Behavior  e.g. frequent rubbing of eyes, tilting head to one side, squinting or frowning, excessive blinking, bumping into objects, confusion with alphabets or watching TV and reading too close
  3. Complaints of headache or nausea, blur or double vision, unusual sensitivity to light

Loss of vision can occur ;

  • Suddenly ( e.g. Acute glaucoma, Chemical burns, Retinal detachment) or
  • Gradually (e.g. Refractive error, Cataract, Glaucoma, Diabetic retinopathy, Macular degeneration)

How does one test for visual problems?

  1. Observation of a person’s behavior as described above i.e. appearance, behavior and complaints.
  2. Simple screening with a Snellens chart can be carried out at any of the government health clinics in the country.
  3. For babies and very young children, vision can be tested by moving a colourful toy/ pom-pom by observing child’s eyes following the object.
  4. Other visual field test using confrontation or perimetry, need to be done by trained personnel.

Photograph of Snellen chart (used to check visual acuity)

Treatment

Can blindness be treated?

From the National Eye Survey (1996), 80% of the causes of blindness are treatable or blindness avoidable. They include:

  1. Refractive error through glasses or contact lens
  2. Cataract through surgery
  3. Glaucoma-Medical treatment using eye drops or surgery
  4. Cornea diseases through corneal transplant
  5. Diabetic Retinopathy through regular eye screening and Laser Photocoagulation.

Prevention

Can blindness be prevented?

Blindness due to certain causes can be prevented e.g. :

  • eye infection through early treatment
  • lack of Vitamin A – eating food high in vitamin A
  • protecting eye from injury e.g. chemical burns, welding burns by using protective goggles
  • congenital cataract in babies due to rubella through immunization
    (immunize mother before she becomes pregnant)

Some causes of blindness cannot be avoided e.g. :

  • Genetic conditions e.g. night blindness
  • Age related macular degeneration (Retinal disease due to aging)

Complications

What are the problems faced by those with visual impairment?

A person blind from young:

  • 80% of what a child learnt is through the vision. Therefore a visual impaired child may have difficulty in learning and carrying out activities of daily living such as eating, moving around and self care
  • They need early intervention and special training

An adult who becomes blind

They need to learn to adapt to their visual disability and may require rehabilitation and aids such as using white cane /stick.

Rehabilitation

What can we do for someone who is already blind?

  • Both the child and adult person with visual impairment/ blindness need rehabilitation.

The guardian needs to :

  • Register person with Social Welfare Department, this form can be access through www.jkm.gov.my. This is important so that the statistics of visual impaired person in the country is constantly updated and resources allocated for services.
  • Get rehabilitation activities in the following areas depending on their age; Early intervention for children (at health centres, Community Based Rehabilitation by :
    • Social Welfare, Malaysian Association for the Blind – www.mab.org.my for training on
      • Orientation and mobility
      • Activities of daily living,
      • Recreation
    • Social rehabilitation
      • Learn to interact
      • Learn to communicate with others
    • Educational rehabilitation
      • Learning Braille
      • Acquire low vision devices such as magnifying glass (for those with low vision)
      • Register early with Special Education Department
    • Vocational rehabilitation (preparing for job) e.g
      • Training in massage / reflexology, computing
      • Carpentry
      • Weaving

Where to get the cane?

Support groups

Malaysian Association for the Blind (MAB)
Provides early intervention services and vocational training
Tel (603) 2272 2677
Fax(603) 2272 2676
e-mail : info@mab.org.my

St Nicholas Home , Penang
Provides early intervention services and vocational training
Tel: 04-2265911

Jobstreet.com

Organization that helps the person with disabilities in the community to be integrated into the job force and in various streams of life http://jobs4disabled.jobstreet.com/default.htm

References:

  1. http://www.mab.org.my/reference/blindness.html
  2. M. Zainal, SM Ismail, AR Ropilah, H Elias,G Arumugam, D Alias, J Fathilah, TO Lim, LM Ding, PP Goh. Prevalence of Blindness and Low Vision in Malaysian Population: Results from the National Eye Survey 1996. Br J Ophthalmol 2002;86:951-956.
  3. Manual on the management of children with Visual Impairment, by Family Health Development Division, MOH. Sept 2003
  4. Manual Penjagaan Mata Untuk Anggota Kesihatan Primer, Oct 1997 MOH/K/EIP/30.02(HB)
Semakan Akhir : 21 May 2012
Penulis : Dr. Aminah Bee bt. Mohd Kassim
Reviewer : Dr. Salmah Othman

 

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