Prevention of blindness and deafness

Facts about deafness

In this site, deafness means complete loss of the ability to hear from one or both ears; this is profound hearing impairment, 81 dB or greater hearing threshold, averaged at frequencies 0.5, 1, 2, 4 kHz.

Hearing impairment means complete or partial loss of the ability to hear from one or both ears; this is mild or worse hearing impairment, 26 dB or greater hearing threshold, averaged at frequencies 0.5, 1, 2, 4 kHz.

Disabling hearing impairment means moderate or worse hearing impairment in the better ear; that is the permanent unaided hearing threshold level for the better ear of 41 or 31 dB or greater in age over 14 or under 15 years respectively, averaged at frequencies 0.5, 1, 2, 4 kHz.

A schoolgirl in Africa does not answer the teacher’s question. She may have hearing impairment.

Size of the problem (WHO estimates 2002)

  • 250 million people in the world have disabling hearing impairment (moderate or worse hearing impairment in the better ear, see: Grades of hearing impairment)
  • Two-thirds of these people live in developing countries.
  • Half of deafness and hearing impairment is avoidable.
  • Adult-onset hearing loss ranks 15th amongst the leading causes of the Global Burden of Disease (GBD), and 2nd in the leading causes of Years Lived with a Disability (YLD).

Effects of deafness and hearing impairment on individuals and society

  • Damage to the development of speech, language and cognitive skills in children especially if commencing at birth or during infancy.
  • Slow progress in school.
  • Difficulties in obtaining, performing and keeping an occupation.
  • Social isolation and stigmatization in all ages and both sexes.
  • Profound social and economic effects in communities and countries.
A teenage girl in Asia has been deaf since birth. Her father brings her to a mobile ear clinic for the first time in her life.

These difficulties are magnified in developing countries, where there are generally very few services or trained staff to deal with them.

Gaps and needs

  • Awareness is often lacking about hearing and hearing loss in society, including amongst decision makers, health workers, teachers and parents.
  • National plans and programmes for prevention and rehabilitation of hearing loss are lacking in most developing countries.
  • Primary ear and hearing Care (PEHC) programmes have not been implemented in most developing countries.
  • Secondary and tertiary care programmes need developing or strengthening in most developing countries.
  • Coordinated programmes to provide affordable hearing aids and services need to be set up in developing countries.
  • Many more health and rehabilitation personnel need to be trained in ear and hearing care at the primary and secondary levels and for specialist care in developing countries

Future challenges

Ear examination
  • Numbers and prevalence of persons with deafness and hearing impairment are rising because of increasing world population and lengthening life expectancy.
  • More information is needed to measure the size of these problems and determine their individual, social, and economic effects.
  • Decisive public health action is needed to reverse these increases, especially in developing countries.