JaKe HoSfOrD

            JOURNAL ENTRY WEEK 2

Investigate the two types of sight defect- long-sightedness and short sightedness.

Find the following information:

1. what causes the defect

 the eyeball is too long compared with the focusing power of the cornea and lens. This means light rays from objects in the distance are focused in front of the retina because they’ve been bent too much by the cornea and lens.

Long-sightedness (hypermetropia)

the eyeball is too short when compared with the focusing power of the cornea and lens. This means light rays from near objects are focused behind the retina because they haven’t been bent enough by the cornea and lens.

1. the symptoms displayed

Short-sighted:  Objects in the distance appear blurry

Long-sighted: Headache, eye strain, blurry vision when concerntrating on close objects

1. propose what sort of lens may be used to correct each vision.

Long-sighted: Convex lenses

Short sighted: Concave lenses

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