Comparison of artificial eyes of 
special glass
(cryolith) and acrylic material (PMMA)

 

We provide both types of artificial eyes for our patients. Therefore, you can make your choise.

However, the prostheses of special glass possess some essential advantages over the acrylic material.

We would like to show you with this page the advantages and disadvantages of both philosophies. We have compared them and have made them more comprehensible with the help of some pictures.

 

artificial eye

 

special glass

acrylic material

advantages disavantages avdantages disavantages
smoother surface,
because itīs fire polished
breakable basically not breakable rougher surface,
because itīs mechanically polished
better tolerable,
because itīs inorganic material
a little cooler than the acrylic eye. Therefore a little more noticeable during the winter in winter thermal a little more favorable than the glas eye less tolerable,
allergic reactions on the material may be possible
good to moisten.
The tear fluid forms a gliding film on the glass-surface (hydrophilic)
less to moisten.
The liquid dispenses itself unevenly on the acrylic surface, it is rejected (hydrophobic)

The artificial eye of special glass is made in presence of the patient within a single session and can immediately be insert and worn.

There is no reason for a second visit to the Ocularist.

However, for patients who have a long distance to the ocularist the production of a "replacement prosthesis" would be recommendable.

The patient must visit the Ocularist at least two times.
At the first visit measurement, form and color are determined.
The final adjustment of the prosthesis is made at the second visit.

The production of a prosthesis for the transitional period would be recommendable.

 

The possibility to moisten the surface

Here you can see pictures of an experiment with a fluorescent liquid. The different behavior of the liquids should be shown on the surface of an artificial eye of special glass and one of acrylic material.
Both prostheses are moistened with a liquid drop.
The different reactions of the liquid can be recognized easily. The different tensions of the surface between liquid and the materials are responsible for this phenomenon.

 

special glass acrylic material
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The fluidity behavior on the glass surface (which can be coverd by the tears) is quite natural. The acrylic surface rejects the drop.
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The liquid dispenses itself over the glass surface evenly. On the acrylic surface (which doesnīt get coverd by the tears) it comes to a formation of drops.
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In the case of the artificial eye made of special glass, there is always an even distribution of the liquid covering the surface. The tear fluid acts as a gliding film between lids and prosthesis. By the prosthesis of acrylic material an interruption of the tear fluid can occur. The liquid forms drops. These can irritate the lids and can lead to inflammation.

 

the two surfaces under the electron microscope

picture can be increased by clicking

picture can be increased by clicking

Unworn artificial eye of special glass:
The fire polished surface appears more smooth also with extreme enlargement. (Notice the 25-fold stronger enlargement opposite the other pictures !)
Unworn artificial eye of acrylic material:
Additionally to the surface defects, there are also recognizible the parallel dispersed scratches (for these prostheses typical). These are produced at the last stage of the manufacture, at the polishing.

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picture can be increased by clicking

Artificial eye of special glass: 1 year wearing time
Scratches, from inferior depth and expansion, dispersed into different directions are recognizable.
Artificial eye of acrylic material: 1 year wearing time
Many defects, with until 150 ĩms, are recognizable, which make this prosthesis comparable to a microscopic "grater".

Copyright Đ by Schreiner-institute for artificial eyes

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