How vision works | an animated guide to the human eye functions

The Eye and Vision – How vision works




How vision works in the human eye | an animationThe eye is a complex optical system – very similar to a camera.

Vision begins when light enters the eye through the cornea, a powerful focusing surface. The cornea is what gives us clear vision. From there, it travels through clear aqueous fluid, and passes through a small aperture in the iris called the pupil.

As muscles in the iris relax or constrict, the pupil changes size to adjust the amount of light entering the eye. Light rays are bent and focused through the lens, and proceed through a clear jelly-like substance in the center of the eye called vitreous humor, which helps give the eye form and shape. When light rays finally land on the retina, the part of the eye similar to film in a camera, they form an upside-down image. The retina converts the image into an electrical impulse that travels along the optic nerve to the brain, where it is interpreted as an upright image.



This animation above depicts the light rays’ path through the eyeball as they pass through the cornea, the eye’s lens and vitreous and striking the surface of the retina, the back inner “wallpaper” in the globe of the eyeball.

All of these structures of the eye mentioned here are critically important in the process of visual acuity. Any disease or condition that affects any of these eye components can cause vision decrease or loss, or even blindness.

Legal blindness is a very depressing and costly problem in the United States and the rest of the world. Low vision can lead to depression and decrease the ambulatory abilities of its victims. It is important to treat these secondary complications as well as the eye disease or conditions. Eye disease illustrations can be seen here.

Pars Plana Vitrectomy Eye Surgery

Vitrectomy is a surgery to remove the vitreous humor from the eye.




Pars plana vitrectomy animation

Vitrectomy is when the eye surgeon removes the vitreous from the inside of the eye.

Pars plana vitrectomy is a general term for a group of operations on the deeper part of the eye, all of which involve the removal of some or all of the vitreous – the eye’s clear internal jelly. Pars plana vitrectomy eye surgery is sometimes done to remove eye floaters or vitreous hemorrhage inside the eyeball. In a vitrectomy, the surgeon “vacuums” out the normally clear, jelly-like fluid that fills the inside of the eye, the vitreous humor, with a surgical instrument called a vitrector.

The vitrectomy procedure

A pars plana vitrectomy is normally an outpatient procedure and very rarely entails an overnight stay in a hospital. Either local or general anesthesia numbs and sedates the eye surgery patient. A special sterile instrument, called a speculum props the eye open during the procedure. The surgery technicians will cover the other eye with a sterile drape and closed the entire time.



The procedure begins with the vitreo-retina eye surgeon making a small 2 millimeter slit in the side of the eye before he inserts an infusion tube in order to maintain constant intraocular eye pressure. He then inserts a tiny microscopic cutting device into another small incision in the sclera, or the “whites” of the eye. This device then aspirates, or vacuums out, the cloudy vitreous fluid.

An aqueous fluid replaces the vitreous fluid that is now missing, in order to keep the normal roundness of the eyeball and to maintain normal intraocular pressure in the eye. The artificial fluid used is saline solution. The eye will naturally replace this artificial fluid with its own clear fluids, within 24 hours.

Risks of vitrectomy eye surgery

As a result of highly technical surgical instruments, pars plana vitrectomy surgery has become very safe during the past couple decades due to evolving technologies. New smaller instruments and novel incision techniques reduce the risks of vitrectomy surgery greatly. However, as with any eye surgery, there are risks. These risks include, but are not limited to:

  1. Endophthalmitis eye infection
  2. Cataract
  3. Retinal detachment
  4. Glaucoma
  5. Bleeding in and around the eye
  6. Macular edema, swelling inside the eye
  7. Additional surgery
  8. Complete loss of the eye / vision

Consequently, special caution and consideration is taken by the eye surgeon and ophthalmic staff to avoid any of these risks and complications.

Cataract surgery vision correction with premium lens animation

Cataract Surgery Vision Correction




Cataract surgery with IOL implant animation

This animation depicts modern cataract surgery with phacoemulsificaiton of the lens and IOL implantation.

Laser cataract surgery is an FDA-approved procedure. This vision correction procedure does not actually use a laser to remove the cataract but femtosecond laser performs many of the traditional steps in cataract surgery.

Cataracts are the leading cause of visual loss in adults age 55 and older and the leading cause of blindness worldwide. By age 65, most people develop cataracts. In the United States, cataract surgery is very successful. In fact, through advances in both cataract surgery and intraocular lenses (IOLs), more people gain back useful vision through this modern lens surgery.



Femtosecond laser cataract surgery

Recently, advances in laser technology have led to the development of a new laser surgery technique for treating cataracts. This new technique is known as femtosecond laser surgery.

What is a cataract?

A cataract affects the lens of the eye. The lens is normally clear, but with age and certain eye conditions, a cataract can develop, causing the eyesight to become blurry, as light cannot pass through the lens correctly. Cataracts can develop in one or both eyes. The cloudier the lens, the worse the vision and the greater the need for the surgery.

Cataract surgery

In traditional cataract removal surgery, an incision is made with a steel blade or a diamond knife. The surgeon then removes the broken up pieces of the natural lens. Afterwards, the surgeon positions a new lens (intraocular lens) in the eye to replace the old. Cataract extraction is one of the safest surgeries to be sure. However, its quality and precision depends on the surgeon’s skill.

Removing the cataract involves creating an opening in the extremely thin membrane (capsule) that covers the natural lens of the eye. Traditional methods using handheld surgical tools are generally safe but the new femtosecond laser process has been shown to be more accurate by far in over 90% of all cases studied.