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BACKGROUND
The blind spot is the small part of the visual field of each eye where there are no photoreceptors namely rods and cons. This corresponds to the optic nerve head or optic disk. It is located to the left of the center of vision for left eye and right of the center of vision for right eye. The visual fields overlap when both eyes are open and hence blind spot is not perceived as the brain has the ability to “fill in” the missing portion of the image. The optic disk is the entry point of retinal vessels, beginning of optic nerve which is located on the nasal side of macula lutea, oval in shape and around 1.5 mm in diameter.1
The aim of the experiment is to characterize of blind spot.
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REQUIREMENTS
Subjects: Human
Apparatus: Paper & marker
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PROCEDURE
The subject is asked to look at the sheet of paper where the dot and plus sign are marked 6-8 inches away. This sheet of paper is held at a distance of 20 inches from the eye. Close right eye and focus on the dot. Slowly bring the paper closer and closer to the eye while looking at the dot. At one point the plus sign disappears. This is the blind spot of the right eye. Repeat the process while focusing on the plus sign for the left eye. The point where the dot disappears is the blind spot for the left eye.2
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CONCLUSION
The blind spot assessment is also helpful in diagnosis of migraine, glaucoma, macular degeneration or retinal detachment.3
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REFERENCES
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https://www.britannica.com/science/blind-spot. Accessed on 29 March 2018.
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https://faculty.washington.edu/chudler/chvision.html. Accessed on 29 March 2018.
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https://www.verywell.com/what-is-a-blind-spot-3421929. Accessed on 29 March 2018.
