Children’s Vision

1. Children’s Vision Nova Scotia Association of Optometrists

2. Light • Light is electromagnetic radiation • Light travels in straight lines unless something bends it: REFRACTION • Light travels fast (300,000 km/second)

3. How the eye works Light is focused by the cornea, travels through the pupil and then is focused by the lens. Images are made on the retina and the optic nerve carries information to the brain.

4. Photoreceptors • Photoreceptors are light sensitive cells inside the retina • Cones are more densely collected in the central retina (especially the fovea) and they detect color and sense fine detail. Cones need bright light. • Rods are found in the peripheral retina; they function in dim light and detect motion.

5. Some statistics… • 80% of learning is visual. • Canadian National Institute for the Blind, The Right to Sight Handbook, 1978 • It is estimated that approximately 25% of school-age children have vision problems. • Roberts, J. Eye examination findings among children, United States. Vital and health statistics, Series 11, No. 115, DHEW (HSM) 72-1057, Rockville, MD, June 1972 • Roberts J. Eye Examination findings among youths ages 12-17 years, United States, Vital and health statistics, Series 11, No. 155, DHEW Publications (HRA) 76-1637, Rockville, MD 1975 • Peters HB. Vision care of children in a comprehensive health program. J Am Optom Assoc 1966; 37(12):1113-18 • 60% of children experiencing reading difficulties are estimated to have an uncorrected or undetected vision problem • Roberts, J. Eye examination findings among children, United States. Vital and health statistics, Series 11, No. 115, DHEW (HSM) 72-1057, Rockville, MD, June 1972 • Roberts J. Eye Examination findings among youths ages 12-17 years, United States, Vital and health statistics, Series 11, No. 155, DHEW Publications (HRA) 76-1637, Rockville, MD 1975

6. Types of Vision Problems… • Myopia (nearsighted) • Hyperopia (farsighted) • Astigmatism • Strabismus (turned eye) • Amblyopia (lazy eye)

7. Types of Refractive Errors • Myopia (near-sightedness): image forms in front of the retina. The optics of the eye are too strong or the eye is too long. • Common symptoms: blurriness of tv, roadsigns or blackboard • Squinting to see • Hyperopia (far-sightedness): image forms behind the retina. The optics of the eye are too weak or the eye is too short. • Common symptoms: near blur, headaches and tired or aching eyes

8. Astigmatism • The cornea is shaped more like a football than a soccer ball • Low degrees cause strain and discomfort • High degrees cause distorted and blurred vision • Distance and near are blurred/strained • Can be corrected with glasses made equal but opposite to the corneal distortion

9. Refractive Error Correction • CONVEX or POSITIVE lenses will CONVERGE or FOCUS light and can form an IMAGE • Farsighted people require positive lenses to be in focus

10. Refractive Error Correction • CONCAVE or NEGATIVE lenses will diverge (spread out) light rays • Myopic people require negative lenses to be in focus

11. Strabismus/Turned eye • One eye is turned in or out independently of the other • Can result in amblyopia (lazy eye) • May be corrected by surgery, glasses or a combination of both

12. Amblyopia/Lazy Eye • During development, one eye (or both) does not develop fully • Can result from high myopia, hyperopia, or astigmatism • Often develops secondary to uncorrected strabismus • Can be treated effectively if detected early enough • Glasses, vision training, patching therapy

13. Amblyopia continued… • If a child has been diagnosed with any of these conditions, they may be fit with spectacles and, in cases of amblyopia, instructed to wear a patch over their good eye. You can be a tremendous help in the classroom by making sure glasses are worn when necessary and the patch remains on for the appropriate duration (indicated by the optometrist). When the visual system is working correctly, learning can progress without visual impediment.

14. Possible Problems with Eye Movement Control • Tracking – eye motor movements – eg. To smoothly follow lines of text on a page • Saccades – eye movements between targets – eg. To move from one word to the next • Symptoms • Loss of place while reading • Inaccurate copying from board

15. How do we treat these vision disorders? • Myopia, hyperopia, astigmatism • glasses • Strabismus/turned eye • Glasses, prisms, and/or surgery • Amblyopia/lazy eye • Glasses, patching, vision training

16. Squinting Blurred vision Headaches or nausea after visual concentration Double vision Crossed or turned eyes Avoidance of close work Frequent eye rubbing or blinking Short attention span Close working distance when reading Difficulty changing focus from distance to near Frowning or squinting to see TV or signs Symptoms of Vision Problems

17. Problems to watch for in school… • Short attention span/frequent daydreaming • Turning or tilting head to use one eye • Closing or covering one eye while working • Losing place while reading • Trouble finishing written timed assignments • Difficulty remembering what has been read • Omitting, repeating and miscalling words

18. More indicators… • Age-inappropriate reversals of letters • Difficulty remembering, identifying and reproducing basic geometric forms • Poor hand-eye coordination when copying from the chalkboard, throwing or catching a ball, or tying shoes • Displaying evidence of developmental immaturity

19. What can you do? • Make sure glasses are worn when appropriate • Watch for any warning signs • Work with parents in achieving goals • Suggest an eye exam if you have any concerns

20. What is assessed in an eye exam? • Visual Acuity • What is meant by 20/20 vision? • Refractive Error • Myopia, hyperopia, astigmatism etc. • Stereoacuity • Ability to see in 3 dimensions (depth perception) • Binocular Vision • Ability of the eyes to work together • Ocular Health • Are the eyes healthy?

21. Vision Screening vs. Eye Exam • Not comparable • Seeing 20/20 does not mean you have perfect vision • A vision screening tests very effectively for some vision defects, but not others • All 5 components of vision should be assessed (visual acuity, refractive error, stereoacuity, binocular vision, ocular health)

22. NSAO Recommendations • Children should have their first eye examination at the age of 6 months, again at age 3 and regularly thereafter.

23. Optical Illusions