lacrimal glands, eyelids, eyebrows and eyelashes, and lacrimalsac
how are images formed in the eye
Light passes, cornea to the pupil.Opening, can increase or decrease in size, depending of the light.Crystallinelens adapts, bring the image into focus and projects it onto the retina. In the retina, lightstimuli. Two types of photoreceptors: • Cones, colours • Rods, peripheral and lowlight.Photoreceptors in the retina transform the lightstimulus into a nerveimpulse.Optic nerve to the brain.
hypermetropia
Nearby objects are seen out of focus. • Eyeball is too short. • Images are formed behind the retina. • Convex lenses
myopia
Distant objects are seen out of focus. • Eyeball is too long. • Images are formed infront of the retina. • Concave lenses.
astigmatism
• Abnormal curvature of the cornea. • Multiple points of focus in the retina. • Special lenses.
eye care measures
• Glasses, avoid exposure to sunlight. • Avoid touching your eyes. • Adequate light, avoid reading in low light. • Limitthetime in front of electronicdevices.
parts of the eye involved in sight
Cornea, focuses the light.Iris/pupil (the hole). Controls the amount of light.Crystallinelens.Deformable lens, focuses the image in the retina.Retina. Detects light.Cones, they detect colours (R, G, B) and they needintenselight.Roods, are sensitive, they do not differentiate colours.