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  • Symptoms

    Vision - night blindness

    The cornea allows light to enter the eye.  As light passes through the eye the iris changes shape by expanding and letting more light through or constricting and letting less light through to change pupil size.  The lens then changes shape to allow the accurate focusing of light on the retina.  Light excites photoreceptors that eventually, through a chemical process, transmit nerve signals through the optic nerve to the brain.  The brain processes these nerve impulses into sight.

    Night blindness is poor vision at night or in dim light.

  • Symptoms

    Vision problems

    People are very sensitive to other individuals' eye positions.  By looking at another person's eye position, one can very effectively gauge where they are looking.  People are also sensitive to eyes that are not looking in the same direction, which is referred to as crossed eyes (strabismus).  Other more specific medical terms refer to eyes turned either outward or inward, or that are abnormally rotated.  Any appearance of crossed eyes in young children should be immediately evaluated, as should recent onset of crossed eyes in an adult.

    There are many types of eye problems and vision disturbances, such as: Halos Blurred vision (the loss of sharpness of vision and the inability to see fine details) Blind spots or scotomas (dark “holes” in the vision in which nothing can be seen) Vision loss and blindness are the most ...

  • Test

    Visual acuity test

    The eye is the organ of sight, a nearly spherical hollow globe filled with fluids (humors). The outer layer or tunic (sclera, or white, and cornea) is fibrous and protective. The middle tunic layer (choroid, ciliary body and the iris) is vascular. The innermost layer (the retina) is nervous or sensory. The fluids in the eye are divided by the lens into the vitreous humor (behind the lens) and the aqueous humor (in front of the lens). The lens itself is flexible and suspended by ligaments which allow it to change shape to focus light on the retina, which is composed of sensory neurons.

    The visual acuity test is used to determine the smallest letters you can read on a standardized chart (Snellen chart) or a card held 20 feet away. Special charts are used when testing at distances shorter than 20 feet.

  • Test

    Visual field

    The eye is the organ of sight, a nearly spherical hollow globe filled with fluids (humors). The outer layer or tunic (sclera, or white, and cornea) is fibrous and protective. The middle tunic layer (choroid, ciliary body and the iris) is vascular. The innermost layer (the retina) is nervous or sensory. The fluids in the eye are divided by the lens into the vitreous humor (behind the lens) and the aqueous humor (in front of the lens). The lens itself is flexible and suspended by ligaments which allow it to change shape to focus light on the retina, which is composed of sensory neurons.

    The visual field refers to the total area in which objects can be seen in the side (peripheral) vision while you focus your eyes on a central point.

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