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Can eyes adapt to defocus?

Can eyes adapt to defocus?. By : Kristian Galan Mentors: Frances Rucker & Olufunke Adeusi. Introduction. The goal for this experiment is to see if the eye adapts to defocus. Adaptation is when the eye changes its sensitivity to maintain good vision. Vocabulary.

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Can eyes adapt to defocus?

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  1. Can eyes adapt to defocus? By: Kristian Galan Mentors: Frances Rucker & Olufunke Adeusi

  2. Introduction • The goal for this experiment is to see if the eye adapts to defocus. • Adaptation is when the eye changes its sensitivity to maintain good vision.

  3. Vocabulary • Choroid~ thin vascular layer between the sclera and the retina. It supplies blood to the retina and conducts arteries and nerves to other structures in the eye • Retina~ the nerve layer that lines the back of the eye. It senses light and creates impulses that travel through the optic nerve to the brain

  4. Vocabulary (cont’d) • Defocus~ when images aren’t focused directly on the retina • Lens~ used to correct defocused images. In this experiment we are inducing defocus with lenses. • Hypermetropia~ when an image is focused behind the retina • Myopia~ when an image is focused in front of the retina

  5. Equipment/tools • White Leghorn chicks • + and - lenses(+6, -6.5) • Ultrasound • Refractometer (Refraction) • Anesthetics

  6. Movie

  7. Procedure • Measurements of the chicks eyes are taken before exposing the chicks to the lenses, using both ultrasound and refraction • A negative lens was put on the chick’s right eye for 2 days to create a state of hypermetropia • The lens was taken off 4 times a day for 15 minutes each time to prevent the eye growing to compensate for the hypermetropia • On the third day we measured the eyes again. We then put positive lenses on both eyes of the chick to create a state of myopia for four hours. After that the eyes were measured again.

  8. Results

  9. Results (cont’d) • The choroid in the control eye did not thicken as much as the choroid in the experimental eye. • The choroid response in the experimental eye was more sensitive to plus lens defocus. • The eye appears to adapt to having the minus lens on.

  10. Further experiments • Because we have only tried this with the minus lens, we plan to do the same experiment using positive lens first followed by a minus lens.

  11. References • http://www.crypticscriber.com/dump/eye.gif • http://www.dblink.org/images/et-fig9.JPG • http://www.Medterms.com

  12. Acknowledgements • Dr. Frances Rucker • Olufunke Adeusi • CCNY • Dr. Sat • Harlem Children Society

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