Date post: | 30-Dec-2015 |
Category: |
Documents |
Upload: | colleen-sparks |
View: | 36 times |
Download: | 1 times |
Can eyes adapt to defocus?
By: Kristian GalanMentors: 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
• 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
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
Equipment/tools
• White Leghorn chicks• + and - lenses(+6, -6.5)• Ultrasound• Refractometer
(Refraction)• Anesthetics
Movie
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.
Results
-200
-100
0
100
200 Δ choroid thickness
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.
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.
References
• http://www.crypticscriber.com/dump/eye.gif
• http://www.dblink.org/images/et-fig9.JPG
• http://www.Medterms.com
Acknowledgements
• Dr. Frances Rucker
• Olufunke Adeusi
• CCNY
• Dr. Sat
• Harlem Children Society