September 7, 2012 | POSTED BY | Articles, Healthcare

When a person’s eyes need a visual correction one would think that the best solution to this problem would be to prescribe a pair of prescription glasses. With the advent of contact lenses it has been quite a feat to put a piece of plastic on the surface of your cornea and correct your vision. This modality has provided people the option to choose from either glasses or contact lenses and it has moved the field of optometry forward.

The idea to put lenses on the eye to correct refractive error was first introduced in the late 1800’s. A handful of doctors began to create a demand for the functional application of lenses. Dr. Adolf E. Fick (http://en.wikipedia.org/wiki/Adolf_Gaston_Eugen_Fick) first introduced contact lenses made of blown glass and he used these on the eyes of rabbits. He had observed that the contact lenses after a wear time of 8 hours started to create corneal edema, which is a condition of the lack of oxygen to the cornea. He then did human trial applications. The trials were a great success but these lenses did not have any visual correction.

At about the same time, Dr. Eugene Kalt started to design lenses to place on the eye to correct the conditions of irregular astigmatism. Keratoconus is a corneal condition in which the cornea starts to develop a steep apex, causing irregular astigmatism. The idea was to vault the apex to its natural curvature. This treatment for keratoconus proved successful in improving vision and also proved that contacts can correct vision. It was later realized that contact lenses could successfully correct a person’s refractive error. Another individual by the name of August Muller successfully corrected his high myopia of 14 diopters using contact lenses. He wore the lenses himself and worked to create several molds of contact lenses by designing lenses with different curvatures to be applied to the eye.

The drawback for these early contact lenses was the material. It was not until 1934 when the introduction of PMMA plastic (polymethylmethacrylate) continued the evolution of contact lenses. This new material was optically clear like glass and could be molded, tinted, and modified to fit the surface of the eye for a better fitting lens. Several other doctors of the time took advantage of this advancement in technology to push forth the idea of contact lenses.

Ernest Mullen hoped for a device that could be placed on the eye for visual correction. He contacted Dr. William Feinbloom and questioned the idea of using blown glass altogether and asked the advice of Dr. Theodore Obrig who also wrote an article regarding early contact lens use. With the help of Dr. Obrig and Dr. Edgar D. Tillyer, they began to develop a fitting set made from PMMA material using blown glass molds of current glass contact lens patients. Dr. Obrig used these new lenses and proved they were superior to blown glass lenses.

With the PMMA lenses proving successful in the correction of vision, the material still was not ideal for application to the eye. The lenses were not permeable to oxygen or other gasses. This is a problem, because the cornea needs oxygen to keep it optically clear. The work with another material, called HEMA (hydroxyethylmethacrylate) proved that there are materials that can allow some gas exchange with the lenses. These lesnses were rigid gas permeable and were developed in a small contact lens lab by Dr. Leonard Seidner and Joe Seidner. But the material still was far from ideal for lens application.

It was not till the 1970’s was when the material of HEMA proved to be suitable for orbital application. Dr. Otto Wichterle is the man credited with inventing the soft lens. The lenses were made of HEMA material that simulated living tissue and remained optically clear in contact lens application. Dr. Wichterle took a big step forward by providing these lenses to a group of optometrist who took advantage of the opportunity to work with this material in the U.S. Dr. Robert J. Morrison in Harrison, PA, received some lenses to use for his patients from Dr. Wichterle and worked in improving the use of the material. Maximillian Dreifues, the first to work with HEMA material, Dr. Morrison and Dr. Wichterle worked together by using the material to make a better and more comfortable lens for patients.

The lens material was a great medium to understand how the eye will respond to an application of a contact lens. Lens designs were refined to not only improve vision, but to also improve comfort and tear exchange. This changed the approach and popularity by proving a better lens that a patient could wear longer. It was later discovered that silicone could be used as an efficient material to use for contacts as well. This lens material seemed to have many advantages for its properties of high permeability, stability, flexibility, and durability. High permeability meant that the lenses provided more oxygen to the eye and better comfort. The problem with the material was surface deposits on the lenses.

These uses have proved a great response to the initial application of contact lenses in the practice of optometry. The avenue for other uses for lenses would include administration of medicine to the eye, colored contacts to mask iris color, and bandage lenses for therapeutic applications.

We have come a long way from blown glass and the lens companies are always improving their materials and applications methods. From presbyopic lenses, to orthokeratolgy it seems that there is no end in sight for the contact lens world. Starting from the idea of a contact lens improving vision, to becoming a complete alternative to patients wearing glasses, the contact lens has proven to be a major influence to the field of optometry.

 

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