Medical Animation still showing the cells inside retina
The human eyes looks somewhat like an asymmetrical globe in shape and on average is approximately an inch in diameter. Its front part consists of :
- Iris is the part that is colored
- Cornea is a transparent dome over the iris
- Pupil allows the light to come in and is the black colored circular shaped opening in the iris
- Sclera is the white colored part of human eyes
- Conjunctiva is the lean tissue layer that covers the whole front part of the eye, not including cornea
The lens is just behind the iris and pupil, that aids in focussing light on the rear of the eye. Vitreous, which is a clear gel, fills most of the eye. The light projects via the pupil and lens to its rear. Retina, the peculiar light-sensing cells cover the inside lining of the eyes.
Retina transforms the light into electrical impulses. The impulses are carried to the brain by the optic nerves which are behind the eye. The central vision is provided by macula, which is a miniature extra-sensitive area in the retina.
The pigment type and amount in iris forms the eye color, which is determined by several genes inherited from the parents.
Some of the key eye conditions are listed below:
- Macular Degeneration (age-related): Causes deterioration of the central vision as one ages.
- Amblyopia: This condition begins in childhood. The vision in one eye is greater than the second one which makes the brain prefer that eye. The weaker eye is named the “lazy eye”.
- Astigmatism: In this condition the issue is with the curvature of cornea. In this condition the eye finds it difficult to focus light onto the retina in the desired the way. This results in blurry vision which could be fixed by contact lenses, glasses or surgery.
- Black eye: This is the discoloration or swelling around the eye due to a face injury.
- Cataract: In this condition, one experiences blurred vision due to clouding of the internal lens of the eye.
- Conjunctivitis: In this condition, the conjunctiva gets inflamed or infected which results in “pinkeye”. This often happens due to allergies, bacterial and viral infections.
- Corneal abrasion: This is a scratch on the clear part of the eye’s front. The common symptoms are light sensitivity, pain in the eye.
- Diabetic retinopathy: The blood vessels in the eye are damaged by high blood sugar and it overtimes starts to affect the vision.
- Diplopia (double vision): This is a serious condition that results in seeing double.
- Glaucoma: This condition happens due to increased pressure in the eye and creates vision loss over time.
- Hyperopia (farsightedness): There is difficulty in clearly seeing the near objects. The eye is “too short” for the lens to focus light properly on the retina.
- Myopia (nearsightedness): There is difficulty in clearly seeing the far objects. The eye is “too long” for the lens to focus light properly in the desired way on the retina.
- Optic neuritis: In this condition there is inflammation of the optic nerve mostly due to an overactivity in the immune system. There is vision loss and pain in one eye as a result usually.
- Retinitis: In this condition the retina gets infected or inflamed. It may be due to some infection or from a genetic condition developed over years.
- Scotoma: In this condition the visual field has a dark spot.
- Strabismus: In this condition the eyes don’t point in the same direction.
Above listed are some of the most common conditions in the eye, however, there are some more in addition to above such as pterygium, uveitis and a few others.
Ophthalmology: Understanding How The Eye Works
Of all the specialties of medicine, ophthalmology keeps evolving on a regular basis.
Even the failures in ophthalmology are never really failures. No technology is ever discarded. It may gain popularity later in the marketplace or may be re-developed to a more innovative one, but never discarded.
Eye Parts and Functions
The retina, which sits at the back of the eye, is a thin layer of tissue that contains millions of tiny light-sensing nerve cells. These nerve cells are called rods and conesbecause of their distinct shapes.
Talking about the lens, human eyes probably bear the most amazing lenses. It’s possible to stare at the ground one second and watch the airplane fly, the other, very comfortably with the naked eye, unlike a pair of binoculars which takes a while to adjust the focus from near-sight to far. That's because of the super flexible eye lens which is controlled by ciliary muscles which change their shape, and therefore the focus, almost instantly.
Like a camera lens focuses light onto a film, the cornea focuses light onto a light-sensitive membrane called the retina. Light rays reflecting off an object entering the eyes through the cornea are the reason we can see that object.
The function of cornea is to refract the rays that pass through the pupil. The iris controls the pupil, thereby regulating the amount of light passing through it.The light rays then pass through the lens, which changes shape so it can further bend the rays and focus them on the retina.
Cones are concentrated in the center of the retina, in an area called the macula. When there is bright light, cones provide clear, sharp central vision and detect colors and fine details.
Rods are located outside the macula and extend all the way to the outer edge of the retina. They provide peripheral or side vision. Rods also allow the eyes to detect motion and help us see in dim light and at night. These cells in the retina convert the light into electrical impulses. The optic nerve sends these impulses to the brain, which produces an image.
0 Comments: