Assessment of Vision

• Snellen Chart Test


  Tests visual acuity - the ability to distinguish details of an object in a given distance
• Snellen Chart Test

  Normal: 20/20
• Snellen's Chart Test

  Test the right eye first, then the left eye.
• Snellen Chart Test

  Legal blindness: 20/200 - this disqualifies the client from driving
• Snellen Chart Test

  Numerator - indicates the distance of the client from the chart
• Snellen Chart Test

  Denominator - indicates the distance, at which the normal eye can read the letters
• Snellen Chart Test

  Order: R ->L -> Both
• Snellen Chart Test

  Myopia: >20/30 vision
• Snellen Chart Test

  Hyperopia: <20/15 vision
• Ishihara Plate


  Tests color vision; uses a chart composed of primary colors
• Ishihara Plate

  # of plates: 14
• Ishihara Plate

  Normal: 10 or more plates
• Ishihara Plate

  Color deficiency: 7 or less plates
• Ishihara Plate

  Total color blindness: 0 plates
• Ishihara Plate can assess red and green color blindness.
• Retinoscopy


  Determines refractive error of an eye
• Cover-Uncover Test


  Differentiates various types of strabismus or squinting
• Tonometry


  Measure of intraocular pressure (IOP)
• Tonometry

  Normal IOP: 10-21 mmHg
• Tonometry

  Glaucoma IOP: >25 mmHg
• Fluorescein angiography 


  Uses dye to look at the blood vessels in your eye.
• Fluorescein Angiography

  Skin Side Effects: gold tone - at least 24 hours
• Fluorescein Angiography

  Urine Side Effects: deep yellow - at least 24 hours
• Tonometry

  N/I: NOTE the time of the day the test was done; IOP fluctuates; Normally and expectedly increased in the morning
• Amsler Grid


  Simple test for macular degeneration
• Gonioscopy


  A biomicroscopic test that visualizes the anterior chamber angle which diagnoses glaucoma
• Perimetry


  Measurement of the peripheral visual field; loss of peripheral visual field indicates glaucoma
• Perimetry

  Normal: 90°L
• Bjerrum Tangent Screen


  Measures central vision; macular damage causes loss of central vision
• Ophthalmoscopy


  Examines the fundus of the eye; may diagnose retinal detachment and choked disk
• Slit Lamp Biomicroscopy


  Assesses the eye's anterior portion under high magnification and in optical section; can diagnose astigmatism (irregular cornea)
• Cover-Uncover Test

  Differentiates various types of strabismus or squinting

  • Esotropia - inward deviation of the eye/s
  • Exotropia - outward deviation of the eye/s
  • Hypertropia - upward deviation of the eye/s; "sunrise eyes"
  • Hypotropia - downward deviation of the eye/s; "sunset eyes"