History

Introduction

We cannot continue these brilliant successes in the future, unless we continue to learn from the past .

Calvin Coolidge, inaugural US presidential address, 1923

Coolidge was referring to the successes of a nation, but his sentiment could apply to any field of endeavour, including contact lens practice. As we continue to ride on the crest of a huge wave of exciting developments in the 21st century, we would not wish to lose sight of the past. Hence, the inclusion in this book of this brief historical overview.

Outlined below in chronological order (allowing for some historical overlaps) is the development of contact lenses, from the earliest theories to present-day technology. Each heading, which represents a major achievement, is annotated with a year that is considered to be especially significant to that development. These dates are based on various sources of information, such as dates of patents, published papers and anecdotal reports. It is recognized, therefore, that some of the dates cited are open to debate, but they are nevertheless presented to provide a reasonable chronological perspective.

Early Theories (1508–1887)

Although contact lenses were not fitted until the late 19th century, a number of scholars had earlier given thought to the possibility of applying an optical device directly to the eyeball to correct vision. Virtually all of these suggestions were impractical.

Many contact lens historians point to Leonardo da Vinci’s Codex of the Eye, Manual D , written in 1508, as having introduced the optical principle underlying the contact lens. Indeed, da Vinci described a method of directly altering corneal power – by immersing the eye in a bowl of water ( Fig. 1.1 ). Of course, a contact lens corrects vision by altering corneal power. However, da Vinci was primarily interested in learning the mechanisms of accommodation of the eye ( ) and did not refer to a mechanism or device for correcting vision.

In 1636, René Descartes described a glass fluid-filled tube that was to be placed in direct contact with the cornea ( Fig. 1.2 ). The end of the tube was made of clear glass, the shape of which would determine the optical correction. Of course, such a device is impractical, as blinking is not possible; nevertheless, the principle of directly neutralizing corneal power used by Descartes is consistent with the principles underlying modern contact lens design ( ).

As part of a series of experiments concerning the mechanisms of accommodation, Thomas Young, in 1801, constructed a device that was essentially a fluid-filled eyecup that fitted snugly into the orbital rim ( ) ( Figs. 1.3 and 1.4 ). A microscope eyepiece was fitted into the base of the eyecup, thus forming a similar system to that used by Descartes. Young’s invention was somewhat more practical in that it could be held in place with a headband and blinking was possible; however, he did not intend this device to be used for the correction of refractive errors.

In a footnote in his treatise on light in the 1845 edition of the Encyclopedia Metropolitana , Sir John Herschel suggested two possible methods of correcting ‘very bad cases of irregular cornea’: (1) ‘applying to the cornea a spherical capsule of glass filled with animal jelly’ ( Fig. 1.5 ), or (2) ‘taking a mould of the cornea and impressing it on some transparent medium’ ( ). Although it seems that Herschel did not attempt to conduct such trials, his latter suggestion was ultimately adopted some 40 years later by a number of inventors, working independently and unbeknown to each other, who were all apparently unaware of the writings of Herschel.

Glass Scleral Lenses (1888)

There was a great deal of activity in contact lens research in the late 1880s, which has led to a debate as to who should be given credit for being the first to fit a contact lens. Adolf Gaston Eugene Fick ( Fig. 1.6 ), a German ophthalmologist working in Zurich, appears to have been the first to describe the process of fabricating and fitting contact lenses in 1888; specifically, he described the fitting of afocal scleral contact shells first on rabbits, then on himself and finally on a small group of volunteer patients ( ). In their textbook dated 1910, Müller and Müller, who were manufacturers of ocular prostheses, described the fitting in 1887 of a partially transparent protective glass shell to a patient referred to them by Dr Edwin Theodor Sämisch ( ). asserts that the fitting was done by Albert C. Müller-Uri. Fick’s work was published in the journal Archiv für Augenheilkunde in March 1888 and must be accorded historical precedence over later anecdotal textbook accounts.

French ophthalmologist Eugène Kalt ( Fig. 1.7 ) fitted two keratoconic patients with afocal glass scleral shells and obtained a significant improvement in vision. A report of this work, presented to the Paris Academy of Medicine on 20 March 1888 by Kalt’s senior medical colleague, Professor Photinos Panas, acknowledges and therefore effectively confirms that the work of Fick occurred earlier ( ).

Credit for fitting the first powered contact lens must be given to August Müller ( Fig. 1.8 ) (no relation to Müller and Müller, mentioned above), who conducted his work while he was a medical student at Kiel University in Germany ( ). In his inaugural dissertation presented to the Faculty of Medicine in 1889, Müller described the correction of his own high myopia with a powered scleral contact lens. Paradoxically, Müller subsequently lost interest in ophthalmology and went on to practice as an orthopaedic specialist.

The lenses worn by Müller were made by an optical engineer, Karl Otto Himmler (1841–1903), whose firm enjoyed, until the outbreak of World War II, an international reputation for the manufacture of microscopes and their accessories. Himmler must therefore be acknowledged as the first manufacturer of optically ground contact lenses ( ).

Little development occurred in the 50 years subsequent to these early clinical trials. Improvements in methods of scleral lens fitting were described by clinicians such as Dallos, who emphasized the importance of designing the lens to facilitate tear flow beneath the lens ( ). Dallos also went on to develop techniques for taking impressions of the human eye and grinding the lenses from these impressions.

Plastic Scleral Lenses (1936)

Carl Zeiss of Jena, Germany applied for a patent that proposed the manufacture of contact lenses from ‘cellon, celluloid or an organic substance with similar mechanical and optical properties’, which was eventually issued in 1923 ( ). Cellon is cellulose acetate and celluloid is cellulose nitrate plasticized with camphor; therefore this is a reference to a lens made of a plastic material. This was also the first mention of the manufacture of contact lenses by moulding. The Zeiss patents envisaged that contact lenses made from plastic materials would be less expensive, have some flexibility that would improve the fit, be ‘unbreakable’ and offer ocular protection ( ).

It appears that in Germany there may have been some largely unsuccessful attempts to fit plastic lenses from around 1930. It was reported in that year that Zeiss contact lenses moulded from cellon and celluloid lacked the degree of polish achieved with glass lenses and were unstable owing to the influences of humidity and temperature. More serious findings were that they put a ‘tourniquet’ on the conjunctiva in the region of the limbus and caused extensive corneal erosion. These unfavourable results were possibly due to the fact that they were made with a single back scleral radius of 12 mm ( ).

The Rohm and Haas company introduced transparent plastic (polymethyl methacrylate: PMMA) into the United States in 1936, and in the same year, described a scleral lens consisting of an opaque plastic haptic portion and a clear glass centre. Soon after, scleral lenses were fabricated entirely from PMMA using lathing techniques. The earliest report of the fitting of PMMA lenses appears to have been made by Thier in 1939. These lenses were said to be ‘about half the weight of ordinary glass, unbreakable and quicker to manufacture’. They did not provoke any irritation, but the optical zone needed to be repolished every 6 months ( ).

A key rationale for using PMMA for the manufacture of contact lenses was that this material was considered to be biologically inert in the eye. This view was formed by military medical officers who examined the eyes of pilots who suffered eye injuries during World War II as a result of fragments from shattered cockpit canopies (as would occur during aerial dogfights) becoming permanently embedded in the eye. These eyes remained unreactive for years after such accidents. Other advantages of PMMA included its light weight, break resistance and being easy to lathe and polish.

Plastic Corneal Lenses (1948)

The development of corneal lenses began as the result of an error in the laboratory of optical technician Kevin Tuohy. During the lathing of a PMMA scleral lens, its haptic and corneal portions became separated. Tuohy was curious as to whether the corneal portion could be worn, so he polished the edge, placed it in his own eye and found that the lens could be tolerated ( ). Further trials were conducted, leading to the development of the rigid corneal contact lens (rigid lenses were previously referred to as ‘hard’ lenses if they were manufactured from PMMA). Tuohy filed a patent for his invention in February 1948.

So began an era of popularization of the contact lens. The spherical Tuohy lens design suffered from two main drawbacks: considerable apical bearing, which caused central corneal abrasion and oedema, and excessive edge lift, which made the lens uncomfortable and easy to dislodge. It was soon realized that these problems could be overcome by altering the peripheral curvature of the posterior lens surface, heralding the development of multicurve and aspheric designs, which remain in widespread use today, albeit with superior gas-permeable materials (PMMA is now virtually obsolete).