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2. Accommodation:
it’s a process by which the curvature of the lens is increased, and this can be done by contraction of the ciliary muscle which relaxes the lens ligament and the lens spring in to more convex shape this is called accommodation for near vision. 2

3. The near point:
Is the nearest point to the eye at which an object can be brought into clear focus by accommodation, its about 9cm at age of 10 years, while increases at the age of 60 to about 83 cm. This change is due to increase hardness (elasticity) of the lens with advancing age.
Pupillary reflex:
Pupillary light reflex: when light is directed to one eye, the pupil of that eye constricts.
Consensual light reflex: when light is directed to one eye, there will be constriction of the pupil of the other eye. 3

4. Myopia (near sightedness):
Refractive errors:
Myopia (near sightedness):
It is genetic in origin, the anteroposterior diameter of the eye ball is too long. It is corrected by wearing glasses with biconcave lenses.
Hyperopia (far sightedness):
The anteroposterior diameter of the eye ball is too short. It is corrected by wearing glasses with convex shape.
Astigmatism:
The curvature of the cornea is not uniform. It is corrected by wearing glasses with sylindrical lens.
Presbyopia:
By the time normal individuals reach the age of years, there will be loss of accommodation. It is corrected by wearing glasses with convex lenses. 4

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6. Visual acuity:
Tested by snellen’s chart which consist of a series of letters of varying sizes, the top letter is visible to the normal eye at 60 meters, the subsequent lines at 36, 24, 18, 12, 6 and 5 meters respectively.
VA is recorded according to the ratio d/D, where (d) is the distance at which the letters are read, while (D) is the distance at which they should be read. The patient is normally placed at a distance of 6 meters from the chart (6m) and each eye tested separately.
d is the ability of the eye to see the letters.
D is the distance at which the letters should be seen. 60/6, 36/6, 24/6 ……. D=6 & d= 60, 36, 24, 18 …. 6

7. VA can be recorded using a pinhole aperture.
Normal person should read until the 7th line, i.e has a VA of 6/6. If only the top letters are visible the VA is 6/60. VA of less than 6/60 the patient is moved toward the chart until they can read the top letter. If he can read it from 2 meters the VA is 2/60, VA of less than 1/60 is recorded as counting fingers, hand movements, or perception of light.
VA can be recorded using a pinhole aperture. 7

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9. Visual fields:
Is an island of vision surrounded by a sea of darkness. The field of vision is limited both by the area of retina and the margin of the orbit, nose and cheek. The VF is napped with a perimeter, the process is called perimetry. 9

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12. Methods of VF examination:
Confrontation test: in this test the examiner sits about 1 meter distance form the patient compares his own VF to the patients field for each eye separately to notice the movement of the examiners finger in each direction while fixing their opposite eyes on each other.
Red pin test: the same principles as confrontation test used, except in that holding a red head pin instead of moving his fingers.
Perimetry: several types of perimeters are available, but all use the same principles, it varies from the old mechanical perimeter to the automated perimeters. 12

13. The patient is seated comfortably with his chin resting on a chin rest adjusted so that the eye to be tested is oriented at the center of a hemispherical, illuminated field, upon which spots of light of different intensities, colors or sizes are projected, or moved in order to detect the limits of the field. In some perimeters the examiner can observe the patients eye with a small telescopic eye peace in the center of the hemisphere, in order to detect any movement of the patient eye away from the fixation point. 13

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16. Color vision:
Tested by ishihara s chart which are plates of printed figures are made up of colored spots on a background of similarly shaped colored spots, the figures are internationally made up of colors that are liable to look the same as the background to an individual who is color blind. 16

17. Fundoscopy:
The examination of the fundus of the eye with an ophthalmoscope is an essential part of all medical examination. In routine medical examination it is usually possible to examine the optic disk and surrounding retina without dilating the pupil, but for complete examination of the fundus the pupil should be dilated using a mydriatic eye drops. 17

18. The patient should be examined in a dark room, either sitting or lying down. Ask the patient to look straight a head and keep his eyes as still as possible. The ophthalmoscope is held few cm from the patients eye, suitable lens is used in the ophthalmoscope. Opacities in the media (cornea, lens, anterior chamber and vitreous) will appear as black lines against the red reflex. The ophthalmoscope should then be brought as close as possible to the patient s eye.
The optic disk is round or slightly oval, pale pink color and paler than surrounding retina. 18