Contact lenses - the great Zeiss secret?
The ignored and forgotten story retold again at last. Special Subject Adviser to the Museum on contact lenses, the late Tim Bowden, peers deeper into this early history...
The ignored and forgotten story retold again at last. Special Subject Adviser to the Museum on contact lenses, the late Tim Bowden, peers deeper into this early history...
What is taken as the first contact lens was not for the correction of sight but rather for the protection of the eye.
The German origins of cosmetic contact shells
In 1887 Dr Saemich, an ophthalmologist, had asked artificial eye makers F. Ad. Müller & Söhne of Wiesbaden to blow some glass shells, resembling artificial eyes, to protect the cornea of one of his patients who had suffered severe surgical damage to the lids of one eye. As the eye would not close some sort of protection was required to avoid the drying and erosion of the cornea which would result in considerable pain and visual loss to the patient. His other eye was already blind due to cataracts.
The blown shell had a clear central portion through which to look, although this part was not optically powered. It had a wide flange that covered the 'sclera' or white of the eye coloured to match the sclera with the inclusion of small blood vessels. The patient is reported to have worn the lens night and day for twenty years until his death. In reality he would have had a new lens made every year to 18 months due to the effect on the glass of tear-corrosion.
About the same time a paper was published by Dr. Adolf Eugen Fick, a physician in Zurich, reporting how he had fitted contact lenses to traumatised or irregularly shaped corneas. He experimented first with fitting lenses to rabbits having made casts from Plaster of Paris. Later he moulded the eyes of cadavers in the mortuary. One such lens he actually placed on his own eye for about 2 hours without any reported subjective symptoms! He had some lenses blown for him by Müller in Wiesbaden which were approximately 18-20mm in diameter.
Adolf Fick approaches Carl Zeiss
He also approached Professor Ernst Abbe at Carl Zeiss of Jena to grind some glass contact lenses. These had a corneal curvature of 8mm radius and a small scleral band of 12mm radius. The firm of Carl Zeiss had been founded in Jena in 1846. In 1866 Zeiss had engaged the services of Ernst Abbe, a lecturer and later professor of physics at Jena University. Initially Abbe was employed as a freelance researcher but he became a full partner with Carl Zeiss in 1875. Abbe developed a much more scientific approach to the calculation of the optics of the optical instruments. In this same year a young chemist named Otto Schott was awarded his doctorate from the University of Jena. Abbe encouraged Schott to develop a more scientific approach in the making of glass. This led to the development of more than 100 different types of optical and industrial glass that surpassed any other glass previously available. Also in 1881 Carl’s son Roderick became a partner in the firm. All the ingredients were now in place and the foundations laid for the best, most advanced optical company of the era.
Where else would someone trying to develop a whole new method of sight correction go but the greatest optical company of the day? That Fick should approach the firm of Carl Zeiss had a certain inevitability. Carl Zeiss himself died on 3rd December 1888, just when this approach was being made, so it is unlikely that he was personally involved with the development of contact lenses. Robert Heitz reports that Abbe was never very enthusiastic about the project and that he turned to Moritz Von Rohr (1868-1940), a 20 year old scientist who also worked at Zeiss, to calculate the characteristics of a scleral lens. By 1892 Dr E. Sulzer of Geneva was reporting that he had fitted some patients with ground glass lenses made by Zeiss. Obrig says that Sulzer had fitted two keratoconic patients and one patient with high astigmatism gaining good visual results in all cases.
Keratoconus is a degenerative condition where the cornea, which should normally be almost spherical shaped with regular optics, becomes progressively more conical in shape. This results in a very distorted image giving very poor vision that cannot be satisfactorily corrected with spectacles. The only treatments available at the time for the condition were some rather barbaric operations which more frequently resulted in blindness or eye loss. In 1828 Sir John Herschel had suggested the concept of a glass shell in contact with the cornea with some transparent jelly between the lens and the eye to correct this condition. His theory was that if the jelly, or some other transparent fluid, was trapped behind the lens, the distortions would be neutralised. This would work if the tears or jelly had a similar refractive index to the cornea, the front surface of the contact lens thus becoming the primary refracting surface. This theory would also hold for high degrees of astigmatism where the cornea is shaped more like a rugby ball. The spectacle lens technology of the time could not produce a satisfactory outcome.
Early attempts by Zeiss to blow glass contact lenses
It was soon found that the blown lenses of Müller could be quite comfortable but the optics were difficult to control. It has been shown that Helmbold sent 200 blown glass lenses from Wiesbaden to Zeiss to have a superior optic section ground onto the lens. Heinrich Erggelet and Eugen von Hippel, both ophthalmologists from Göttingen, also sent lenses for grinding but all were unsuccessful. Zeiss said it was due to the softness of the glass as this had been developed for artificial eyes. The requirements here were for ease of blowing and for an appearance that was as natural as possible to match the real eye. Müller himself considered it was because of the extreme thinness and delicacy of his shells.
Introduction of Zeiss Scleral Lenses
In 1911 Zeiss added what are now referred to as scleral lenses to their range of products. The scleral or haptic lens was one with a portion to cover the cornea surrounded by a flange to sit onto the sclera or white of the eye. Typically this flange would sit under the top and bottom eyelids. They were ground from solid glass and made to a very high standard of optical precision.
A typical Zeiss lens of the time was round and had a back optic radius of 6.50mm, a back optic diameter of 12.00mm, back haptic radius of 12.00mm, central thickness of 0.86mm, total diameter of 20mm, an edge thickness of 0.55-0.85mm and weight of 0.75g. Zeiss adopted the trade name of Auflageglas for their lenses but changed to Haftglaser before 1920. According to Dr Wolfgang Wimmer of the Zeiss Archive, Auflageglas means a glass that is laid on whereas Haftglaser means glass that is affixed or fastened.
The lenses were afocal in nature, i.e. they had no optical power ground onto them. They relied on the difference in curvature of the back surface of the lens and the front surface of the cornea to produce the optical correction. Spectacles could also be worn over them to fine tune the final level of vision. The cornea would be measured using an ophthalmometer and the curve of the lens was then calculated. This technique sacrificed the fit and comfort of the lens in favour of the optical correction. This was also to compromise the exchange of tears under the lens and therefore the oxygen supply to the cornea. It would be some 40 years later that this really started to be understood.
Zeiss Fitting Sets
In 1912 Carl Zeiss introduced their first contact lens trial set for use in optical practices. A trial set would consist of a number of lenses of known parameters. These would be used by practitioners, (on the Continent mainly by ophthalmologists) to evaluate the fitting of the lenses in the patient's eyes.
Zeiss was the first to take this approach. The fit of the lens was evaluated by the practitioner and ordered from Zeiss in Germany. The lens was made to the chosen parameters with delivery taking about six weeks. The lenses available from the Mülller’s of Wiesbaden, and those that would later become available from Müller-Welt and Dallos, were bespoke, being hand made exactly to the requirements of the patient. Indeed they required many lenses to be made and the process of fitting and adjustment before a satisfactory outcome was achieved. It is unlikely that the Zeiss lenses, once made, would be adjusted in any way to improve fit, comfort or vision. Nowadays all disposable soft lenses are mass produced in the factory with a diminishing number of lenses being hand crafted for individual needs.
Zeiss contact lenses marketed around the world
About this time Edmund Tomkins, a British dispensing optician, joined the Zeiss London Office as technician. One of his roles was to call on ophthalmologists and opticians to talk about contact lenses and the use of the trial sets. Tomkins had some lenses made for himself for demonstration purposes and was perhaps the first contact lens company representative. It is not clear how successful he was.
Also in 1912 Zeiss made some glass corneal lenses. These were much smaller in diameter, possibly about 10-12mm, and were designed to sit on the cornea only and not on the sclera. This, their first attempt, was not very successful due mainly to the weight of the material. They also attempted these in 1923 and 1932 but, due to the inherent problems with glass they not widely used.
In 1913 Shinobu Ishihara of the Teikyo University of Tokyo studied under Professor Stock at Jena University and was exposed to the Zeiss Company and their work with contact lenses. On his return he took with him samples from Zeiss thus introducing contact lenses to Japan.
The development of the Zeiss slit lamp in 1916 also helped with improvements in contact lens fitting technique.
Zeiss produced their first lenses designed specifically for keratoconus in 1918, the year that Eugen von Hippel declared that contact lenses were so successful that he would no longer operate for this disorder. Old habits die hard however in the medical world and an ophthalmology textbook by Sir Stewart Duke Elder of 1945 was still advocating cautery as the best treatment for keratoconus. The Zeiss keratoconic lenses had been designed by Dr W. Stock, who was himself keratoconic. The first Zeiss fitting set consisted of 4 lenses with a 12mm scleral radius and corneal radii of 6.50, 7.10, 8.10, and 9.00mm. By the early 1920s Tomkins, now a partner in Martin & Tomkins Ltd of London, had one of the two Zeiss contact lens fitting sets in the UK. A leading London dispensing company, thought to be Theodore Hamblin Ltd, had the other. Hamblin’s were, later in 1937, to attract Hungarian contact lens pioneer Josef Dallos to settle in London and to found the first contact lens-only practice in the UK.
Albert Wigand of Halle Germany filed an application in 1922 which was granted in 1923 as US Patent number 1,457,804 for a Contact Bowl. He had filed a similar application in Germany in 1918. The patent, which was assigned to Zeiss, was for a contact lens made of Cellon or celluloid. It was envisaged that the lens would be moulded to shape between two lathe-cut moulds. The front surface would be ground and polished to give the final power. The lens could be used for keratoconus, astigmatism, myopia, hyperopia and aphakia. Aphakia is the highly hyperopic state following removal of the crystalline lens of the eye after cataract surgery. The anterior surface of the lens could be protected by a lacquer coating to make it more resistant to the tears. Generally the lens would be less breakable than glass lenses, however, the appearance and discoloration of the material stopped their development by Zeiss.
Contact lenses were discussed at the 42nd meeting of the German Ophthalmological Society in 1922. The use of contact lenses in cases of Keratoconus was discussed as was their use in the rehabilitation of eyes of veterans damaged in the 1914-18 war. Wilhelm Clausen called for a combination of the technically superb ground optic of a Zeiss lens with the more comfortable scleral part of the Mueller blown lens. There were also calls for the consideration of other materials as the glass lens was fragile. This was mainly a problem during handling not while being worn in the eye. A case is cited by Treissman and Plaice of a Zeppelin pilot who fell from his airship to his death. When the lenses were removed from the resulting mess they were found to be intact. Overall they were in much better shape than their erstwhile wearer!
The British use of contact lenses
In the UK it is unclear when the first contact lenses were fitted. The earliest record so far found was of Dick Smellie in 1927 although it is possible that he had been fitting for some years by then. He worked for Theodore Hamblins in Wigmore Street London later becoming the managing director. We can be fairly sure that the first lenses fitted in the UK were made by Zeiss. Arthur Poole, initially for Hamblin’s and later with Keeler’s, also became active with lens fitting around this time. They had encouragement from ophthalmologists Ida Mann and Benjamin Rycroft and later from Andrew Rugg-Gunn, Williamson-Noble and Affleck Greeves. From around 1930 Zeiss lenses were also used by Harry J Birchall of C W Dixey & Son Ltd., Cavendish Square, London. These he fitted until the outbreak of war in 1939.
By 1940, with technician Cyril Winter, Birchall had successfully produced a prototype lathe to cut copies of the glass Zeiss lens design but in the new material of PMMA or 'Perspex'.
Another early exponent of contact lenses in general and Zeiss lenses in particular was Kenneth Osmond Dunscombe. He had qualified in the UK as an ophthalmic optician in 1931 and studied at the University of Jena between 1932-33. Whilst in Jena he did some work with Carl Zeiss and also had a lens fitted. He returned afterwards to his family firm who had four practices in and around Bristol. He was always interested in technical innovation so it is probable that he was fitting contact lenses in Bristol from 1933. The lens that he had made for his own use, is now known as the Dunscombe Lens and resides in this museum.
Further inter-war developments in contact lens design
At the 13th International Congress of Ophthalmology in Amsterdam, 1929, Leopold Heine (1870-1940) an ophthalmologist, Geheimrat or privy councillor and Professor at the University of Kiel University, presented a paper regarding contact lenses and caused a wider interest in their use. His method consisted of using a large number of afocal lenses, made by Zeiss, with varying corneal radii. This utilised the power of the liquid lens trapped between the back of the lens and the cornea. Depending on the curvature of the cornea and the back radii of the contact lens this fluid would exhibit optical power. A difference of 0.50mm between the radius of curvature of the back surface of the corneal part of the lens and the corneal radius would produce about 2.50 Dioptres of power. If the back radius of curvature of the lens was greater, or flatter, than the corneal radius of curvature the liquid lens would have negative power. If the radius of the back of the lens was less or steeper than the cornea it would exhibit positive power. Thus if the corneal radius was 8.00 and the ocular refraction or spectacle power was -5.00 then an afocal contact lens with a back radius of 9.00mm, by the power of the liquid lens thus produced, should correct it. Heine concluded that afocal lenses would not work for gross errors and recommended that contact lenses should be optically powered. The trial sets of 39 lenses that Zeiss produced with Heine had corneal radii from 5mm to 13mm in 0.50mm steps with scleral curves of 11, 12, & 13mm. The lenses were made of crown glass of refractive index 1.516 and were highly resistant to the corrosive action of the tears. The lenses were 20mm in diameter and could have tinted corneal zones of 25%, 50% or 75% light absorption. This helped to offset the photophobia caused by the lack of oxygen to the cornea and improved comfort for those working in bright outdoor environments. Later, curves of 11.50mm and 12.50mm were also added. Subsequently a supplementary set was introduced which added lenses with corneal and scleral curves in 0.25 mm stages for the more frequently used lenses.
By now there were four different types of contact lens:
The latter three were displayed at a contact lens conference in Paris.
Zeiss moulded lens supplied to the American market
The first US published description of the use of a Zeiss trial set appears in May 1929 in the Yearbook of the New York State Optometric Association in a paper by Victor Koch. This showed an improvement of the patient’s visual acuity from 6/300 to 6/6 or 20/20 with the use of over specs. John Neill, who later co-operated with Frank Dickinson of the UK and Wilhelm Söhnges of Germany in the development of the micro corneal lens, William Feinbloom, Theodore Obrig and Bill Policoff also used Zeiss lenses.
Theodore Obrig, a New York optometrist, first became interested in contact lenses about 1930. He fitted Zeiss ground glass contact lenses 'on as many patients with high degrees of myopia, keratoconus and corneal scars as would submit to the ordeal'. Later, in 1935, at his suggestion, Zeiss began making their first impression lenses. Individual casts of eyes were taken from impressions made of the patient’s eyes by the practitioner. The casts were sent to Germany where all the lenses were made and the finished lenses were relayed through the New York office for US customers. Delivery time was quoted as about 4 months. They were oval and made of chemically resistant glass with the corneal portion ground and polished to prescription. Initially the diameter of the corneal part was found to be too small. This was later rectified just before the start of WW2 when supply appears to have ceased altogether.
Introduction of the transition curve and back clearance zone
In 1931 Rugg-Gunn reported that things had not changed much and that developments were held up awaiting developments in other branches of science. The following year two innovations in contact lens design occurred, possibly at the suggestion of Hans Hartinger. One was that a transition curve was ground between the scleral and corneal curves on the inner surface of the lens, thus doing away with a marked junction. The other was to build up the scleral portion to permit a more generous clearance of the cornea without changing the back optic zone radius. Such a change to the transition zone was proposed in US Patent number 1,921,971, a Contact Glass, which had been applied for on the 6th June 1931 and granted on the 8th August 1933. This was in the names of Ferdinand Fertsch and Hans Hartinger, assignors to Carl Zeiss Jena Germany. This applied a spherical transition curve between those of the scleral and corneal parts thus to avoiding the somewhat hard bearing that the previously sharp transition had made on the limbus, the junction between the cornea and the sclera. It also reduced the clearance required between the corneal surface and the back surface of the lens. US Patent number 1,921,972 Contact Glass, by the same authors, applied for 28th June 1930 and also granted on the 8th August 1933 proposed the same idea but using a conical transitional zone.
Around this time Gauldi from Italy researched the Zeiss afocal lenses weighing and measuring each of the 39 lenses in the two types of Zeiss fitting set. Zeiss numbered the lenses according to the scleral and corneal radii with the integer for 10 omitted for brevity Thus:
1/1 has scleral radius 11mm and corneal radius 11mm
1/5 has scleral radius 11mm and corneal radius 5mm
2/0 has scleral radius 12mm and corneal radius 10mm etc.
The first set started at 1/5 and ran to 3/1 with differences of 1mm. The second set was supplied in 0.5mm stages i.e. 1/5.5, 2/5.5 etc. The weight of each lens was found to be 0.5 gms and the scleral diameter was found to be accurate. However, the corneal diameter could be variable even on the same lens and the edges were not uniformly rounded. Gauldi felt that 39 lenses were not enough. Heine agreed and suggested 500 but felt that this would still not be enough especially for the high powers. According to Ida Mann 'The afocal method of varying corneal and scleral curves therefore seems to lead to a reductio ad absurdum'. Heine’s work did much, however, to stimulate other types of lenses such as those of Dallos and Müller-Welt, both of whom visited Zeiss. Indeed US Patent number 1,869,366 Contact Glass by Josef Dallos, assignor to Carl Zeiss of Jena Germany, was applied for on the 31st December 1931 and granted on the 2nd August 1932. A German patent had been applied for on 6th January 1931 and this represents the start of the use of lenticulated front surfaces for contact lenses. By this the power of the lens was restricted to an area smaller than the corneal diameter but larger than the pupil size. By this means, still in use today, the thickness and thus the weight of the contact lens could be minimised. No mean achievement when using heavy glass.
Miscellaneous other developments
Around this same time Zillig, a student at the Zeiss School, Jena, designed a lens with a pinhole aperture and opaque periphery. This lens, working in the same manner as pinhole cameras, reduced optical distortions and increased the depth of focus thus reducing the amount of accommodation needed. This made close vision easier.
A further Zeiss development is found in US Patent number 2,000,768: Method for making Contact Glasses for Eyes. This was applied for on 29th June 1934 and granted on the 7th May 1935 to Rudolph Linche. This showed a method of blowing a glass lens against a mould then subsequently grinding the optic portion. This was the method used to make the impression lenses for Obrig referred to earlier. In this way Zeiss hoped to achieve the comfort of the early blown lenses of Müller of Wiesbaden and the later blown lenses of Müller-Welt of Stuttgart with the precise optics of their own ground lenses.
On 6th May 1937 the world was shocked when the Hindenburg, the largest aircraft ever to fly, burst into flames when it was trying to dock at the naval airfield at Lakehurst, New Jersey, USA. Thirteen passengers, twenty-two crew members and one member of the ground crew were killed. Among the many things lost were a pair of Zeiss contact lenses on route from Carl Zeiss in Jena, Germany to Leo Waldert, an optometrist in Rochester NY. By this time Zeiss had been involved with the manufacture of contact lenses for almost 50 years.
A leaflet from 1944 describes a contact lens made by Zeiss following a paper by W. Comberg in 1927. This has four symmetrically placed lead inclusions around the edge of the optic zone to enable the localisation of foreign bodies or other lesions in X-rays.
It appears that around the start of WW2 Zeiss involvement in contact lenses reduced. There were stories of Luftwaffe pilots wearing corneal lenses but this has yet to be substantiated. It is known that Müller-Welt worked extensively fitting German military personnel with contact lenses. It is also known that at least 85 RAF pilots or aircrew were fitted with contact lenses in the UK by Dallos and Keeler’s. So far little information from this time of Zeiss contact lens activity has come to light.
A Zeiss leaflet dating from 1965 extols the virtues of acid-resistant glass contactschalen. These were glass corneal lenses following up presumably on their work of 1912, 1923 and 1932. A short paper entitled Untersuchungen Uber die Form und Herstellungsart von Cornealschalen aus Silikatglas by Dr E. Noteboom was published in March 1961. This detailed a study on these lenses at the ophthalmic clinic in Karl-Marx Stadt under the direction of Dr Emmrich. Glass was used as it was less flexible and more scratch resistant than plastic and seemingly, according to this study, gave good results. The lenses were eventually launched in three diameters, a range of back optic zone radii and uniform edge thickness across the power range, which was unlimited. All the lenses had the power worked only in the central 6 mm cap to reduce the weight. Nothing has yet come to light regarding their popularity.
It appears that the early work of Zeiss with plastics did not seem to be revived with the invention of polymethyl methacrylate or Perspex in the mid 1930s. The reason for this is unclear. It is probable that with the take over of the Jena plant by the Russians at the end of the war there remained little interest in what could only have been a small part of the Zeiss expertise. Perhaps the need for contact lenses was not perceived as very important by the new overlords. Certainly the first clinic fitting contact lenses in Russia did not appear until 1952 in Moscow.
Ironically Zeiss no longer has much input into contact lens technology after such a great start leading the world of contact lens manufacture. However Professor Heine in Kiel, who did so much work with Zeiss and on the development of contact lenses, did more than he knew. Some time in the 1930s he had fitted a young mechanical engineer with glass scleral contact lenses to correct his +8.00 hypermetropia. His name was Heinrich Wöhlk who was to found, in 1948, a very successful contact lens company of the same name. At one time Wöhlk were joint leaders of contact lenses in Germany with Titmus Eurocon. Up until 1980 the lab was privately owned but they started a collaboration with Zeiss which finally led to their being taken over. From 1990 until 2000 Wöhlk lenses were sold under the Zeiss name but without great success. Times had now changed and the mass market had moved on to disposable soft lenses and neither Zeiss or Wöhlk had expertise in this area. The cost of trying to compete in this field was just too great and the contact lens division was sold to Bausch and Lomb. Their rivals, Titmus Eurocon, did not survive either, now being part of CIBA Vision.
My grateful thanks to Peter Dunscombe, Karin Gjudjenow of the Ernst Abbe Stiftung Optisches Museum Jena, Larry Gubas of Zeiss Historica, Neil Handley of the BOA Museum London, Elisabeth Lowe, Richard Pearson, Klaus Voerste, Wolfgang Wimmer of the Zeiss Archive and the many people who have given their time.
A version of this article first appeared on the Global Contact Lenses website in 2005 and is adapted and reproduced here with their kind permission.