What is Artificial Eye Technology?

Artificial Eye technology is a visual prosthetic system. It is used for replacing dead or damaged eyes. This technology uses a camera that interacts with the brain to simulate the optic nerve. This is a cosmetic process to enhance the appearance of a person with eyes that have been removed. It is not really an eye but it serves as a cover to the eye socket. The artificial eye is also called a fake eye or glass eye. 

Need For Artificial Eye Technology

This technology was created to restore the vision of the visually impaired. Many of the people are affected by visual problems that lead to eye damages or loss of vision. The visual problems may include enucleation, blind/painful eye, ocular melanoma, diabetic retinopathy, trauma, ruptured globe, penetrating eye injury, perforating eye injury, cataract, etc. This technology was needed to provide them with a way to still see the world. 

History

The first user of the visual prosthetic was a woman based in Iran back in 2900 and 2800 B.C. It was made of a light material that is believed to be bitumen paste. It was only one inch in diameter. Its surface made use of the Gold and also had thin strands of gold thread that were used to attach the prosthetic to the woman’s eye socket. It is also believed that Roman and Egyptian priests used such eye prosthetics as early as 5th century B.C. Before World War II, ocular prosthetics were made using a special blown glass that formed a concave shape. During the war, this glass was very difficult to find. As a result, plastics and acrylics were used. In comparison to glass, acrylic eyes were more durable, more comfortable, and needed lesser replacements due to lesser breakage. 

Manufacturing process

The time needed to manufacture an artificial eye is about 3.5 hours. There are two types of prosthetics : 

1. Very thin shell type.
2. Full modified impression type.

The shell type of the prosthetic system is fitted over the blind, disfigured, or partially removed eye. The fully modified version is specially made for people whose eyes have been removed completely due to defects or the eye being dead or potentially harmful. 

The steps involved are as follows : 

1. The dimensions (horizontal and vertical) are measured by an Ocularist.
2. He paints the iris. The iris button is selected to resemble the patient’s eye diameter. It ranges between 10 to 13mm in diameter.
3. The hand carving of the wax molding shell is done. It has an aluminum button for iris. This is inserted in the eye of the patient. 2 relief holes are also made in the wax shell.
4. The impression of the eye is made using a powder from seaweed called alginate. This is also used by dentists to make impressions of gums. This powder is mixed with water and placed behind the wax shell. This gels within 2 minutes thereby giving the impression of the eye socket.
5. EPI retinal Encoder: A retina encoder is used to replicate the information processing by the retina. A radio signal is used to send the visual patterns to the ganglion cells. This is done using a digital signal processor.
6. SUB Retinal Implantation: The neuronal network in the inner eyes are preserved in many cases. This is used to excite the electrical current. The basic features of visuals such as points.

How Artificial Eyes Is Different From Bionic Eyes?

Bionic Eye System: The bionic eyes contain cornea, pupil, lens, retina, iris, and optical nerve. The light that is either radiated or reflected from any object reaches the human eye. The light enters the eyes via the cornea and the pupil is then converged using the lens and the real image that is inverted is made on the retina of the eye. The retina in turn generates electrical signals that are sent to the brain for interpretation. The brain sees the image and processes it as an erect image of the same size as that of the object. 
Artificial Eyes: It can be of 2 types. One type acts as the cover of the eye socket. Another type helps in retaining the volume like that of the original eye. The artificial eyes are made so that they look similar to the bionic eyes of the patient. It is made from plaster of Paris, glass or acrylic and polished so that it shines and resembles the white part of the eye. Aluminum is usually used for the iris, it is painted to resemble the original eye. 

Types Of Eye Removal

The eyes can be removed in the following 3 ways:

1. Evisceration: This method involves the removal of the contents of the inner eye including the iris and cornea. The sclera remains intact with the extra ocular muscles still in place. Usually, an orbital implant is done so that the eyes appear full. An eye cover is also present.
2. Enucleation: In this method, the entire eye is removed. It is carried out in conditions where tumors, infection, the blind eye that is painful, and cases where there is immense stress to the eye. The extra ocular muscles are severed and then attached to the implant.
3. Exenteration: The entire contents of the eye is removed in this case. The eyeball, ocular muscles, and sometimes even the eyelids are removed. A maxillofacial prosthesis is usually used in such cases.

Types Of Implants

1. Nonintegrated implants: Non-integrated implants use acrylic, glass, and silicone materials to make eyes. These implants have been around since 1976.
2. Poly methyl methacrylate (PMMA) (acrylic): Poly methyl methacrylate (PMMA) is also known as acrylic. It is a thermoplastic. These implants have very good mobility. It is very compatible with human skin. It is better in terms of compatibility (more compatible than glass).
3. Integrated implants (porous): The main advantage of using the porous Integrated implants is that they can be used for fibrovascular ingrowth within several months.
4. Hydroxyapatite (HA): The Hydroxyapatite implants are spherical and are made in numerous sizes. It is made using several substances such as coralline or synthetic. One main disadvantage is that it needs a covering material.
5. Porous polyethylene (PP): Porous polyethylene offers a successful implant in most cases, including little propensity in migration and also in restoring defects in an anatomic fashion. It is easily available and cheaper and can also be designed in a custom manner.
6. Bioceramic: This is made of aluminum oxide (Al2O3). It has wonderful features such as low friction, durability, stability, and inertness. Due to such features, it has been used for over 35 years.
7. Conical orbital implant (COI) and multipurpose conical orbital implant (MCOI): This results in a conically shaped ocular implant. It is high in motility.
8. Pegged (motility post) implants: In Pegged (motility post) implants, pegs or screws are added to the implant. This allows motility to the artificial eye. It is also used for hydroxyapatite implants.
   1. It is more precise and enduring than a biological eye.
   2. It can be used to benefit animals as well as humans.
   3. It would provide a means of viewing to the visually impaired and the people whose defects cannot be corrected with surgery.

Disadvantages Of Artificial Eye

1. The final outcome of the implant cannot be known.
2. It would be very expensive technology.
3. All eye patients would not be able to use the artificial eye as it would need certain prerequisites for patients to be eligible for it.
4. Understanding large objects can be difficult.
5. Restoration of the day and night cycle needs to be implemented.