A prosthetic eye is supposed to be in harmony with the other eye with regard to color, shape, and size as closely as possible. Also, it has to be properly fitted into the socket and should not cause any irritation or a health problem.

Prosthetic eyes are generally classified into two groups according to production techniques and the material used:

Stock ready-made prosthetic eyes:

• These artificial eyes are made from glass or acrylic in a variety of standard shapes, colors and sizes, and are kept in stock.
• The artificial eye that appears to fit best is found by a trial and error method. However, bearing in mind that each individual has a unique eye and socket structure, it is easy to predict that these prosthetic eyes seldom give satisfactory results.

2- Custom-made prosthetic eyes:

• An impression of the eye socket is taken with a special impression paste.
• If properly made, matching either the socket into which the prosthetic eye will be fitted or the companion eye that acts as a model will not be a problem with this kind of prosthetic eyes.

Prosthetic eyes are also classified into two types according to the material used:

1- Glass Prosthetic Eyes:

• Impression of the socket is not taken before the production of glass eyes; therefore an accurate match with the companion eye is not possible.
• It is considerably hard to restore the similarity between the two eyes with regard to shape and color with these glass eyes.
• However, glass is a material of high quality. Its wettability by tears is superior than acrylic prosthetic eyes.
• Once manufactured, no alteration is possible; therefore, a new eye has to be made in case of a need for any adjustment.
• It is fragile and easily affected by the constituents of tears, its surface loses its smooth appearance and becomes rough in a short period of time. This may causes serious irritation in most eyes.
• As a whole, its easily degraded surface eliminates its surface advantage over acrylic and it has no superiority over acrylic eyes.

2- Acrylic Prosthetic Eyes:

• It is very strong and not easily broken.
• It can be adjusted for the changes that take place in time.
• When the surface has lost its smoothness and lubrication, it is possible to restore its initial luster and smoothness by a polishing process or surface renewal.
• It is produced by a fine process of polimerization of polymethylmetacrylate powder and the monomer which is very irritant. If the raw material is not produced particularly for prosthetic eyes and the polimerization process is not complete, it may causes persistent irritation, redness, watering, and purulent discharge.

Poor surface properties may cause serious irritation and complaints in case of lack of meticulous care during processing as well.