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Types of Screening for Visual and Eye Examination

Introduction

Vision is among the important sensory modalities for all living organism. However as we aged, vision may be impaired due to normal aging process or eye disorder.

Age- related eye disorders and visual impairment increase with age. An eye survey done in Malaysia in 1996 reported that the prevalence of blindness in children was 0.05 % and increases to 4.77 % in the elderly age 70 years and above.

Many of the age- related eye disorders have no symptoms in the early phase. The disorder progresses slowly in months to years with minimal symptoms. It is not surprising then that many of the elderly do not complaint of visual problem until it is too late.

Common causes of visual impairment in the elderly include cataract, refractive disorder, glaucoma, retinal diseases and age related macular degeneration. Many of the causes are preventable and treatable with early detection.

What is the meaning of eye or vision screening?

Vision screening is a way to detect eye disorder in a person who does not have any symptoms and signs.

Therefore, screening is done in apparently healthy person.

How does vision screening helps to preserve good vision in the elderly?

Its aim is to detect any eye disorder early even though the person has no symptoms. Hopefully with appropriate management, vision can be preserved. Most of the causes for visual impairments are preventable and treatable if detected early.

What are the components in vision screening?

When you go for eye screening, there are few questions and tests that will be performed on you.

History taking includes:

  • Do you have any vision problem? Can you see clearly?

  • Do you need to strain your eyes when looking at a distance or when reading

  • Do you have difficulty driving at night due to light glare

  • Any history of eye disorder or treatment

  • Specific questions to identify any risk factors for visual impairment

Test for visual acuity:

  • This test is to determine the smallest letter or object that you can read on a standard chart (Snellen chart)..

  • You are required to stand 6 meters away from the chart.

  • You will have to remove your glasses or contact lenses initially.

  • Each eye will be tested separately by closing or covering one eye with a pad.

  • You will be asked to read from the largest to the smallest print using one eye that is being tested.

  • The procedure will be repeated with glasses or contact lens on.

  • The procedure will be repeated with you looking through a pinhole for each eye. This test will provide information on refractive disorder.

  • You will also be asked to read prints on a card held 14 inches from your face to test near vision.

Test for visual field:

  • This test is to determine any defect in central and peripheral vision. Defect in central and peripheral vision can be caused by certain diseases such as glaucoma, brain tumour, stroke or other neurological disorders.

  • Each eye is tested separately by closing or covering one eye.

  • You are asked to map down the area where the objects are seen while focusing your eye to a point in the centre.

  • This test can be done manually or using an automated perimetry.

  • Normal result means that the peripheral vision is intact.

  • Other disorders that may affect peripheral vision include diabetes, hypertension, macular degeneration, multiple sclerosis and hyperthyroidism.

Funduscopy:

  • Assessment of the eyes include examination of the back of the eyes or fundus.

  • Other structures of the eye such as the lens, vitreous humour and retina can be examined by using a funduscope or ophthalmoscope.

  • This examination is done to assess the health status of these structures as certain diseases may affect a particular structure. For example routine funduscopy examination is done annually in patient with diabetes to detect early diabetic retinopathy and prevent blindness.

Intraocular pressure:

  • Intraocular pressure is the pressure of fluid inside the eyeball. The fluid pressure can be measured by using a tonometry.

  • Measurement of intraocular pressure is important to determine risk of glaucoma.

When and how often do you need to go for an eye screening?

Those with risks need to be screened as soon as possible and regularly thereafter. Duration of interval depends on the individual problem.

Screening should be done for every 12 months.

Where can you have your eye screening done?

Health centers either public or private may provide screening for vision. Services may be limited to just visual acuity check to a full range of visual screening. Find out from the center nearest about the services provided.

Retail outlets with optometry service may offer some range of eye screening.

Referral to the ophthalmology clinic or optometrist may be done in relevant cases.

References

  1. K.Y Loh, J. Ogle Age Related Visual Impairment in Elderly Med J Malaysia Vol 59 No 4 Okt 2004

  1. 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

  1. 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

Last Review : 03 October 2013
Writer : Dr. Radziah binti Abd. Rashid