The College of Optometrists

 

The timeline of contact lenses begins with a false dawn in the early modern period but gathers pace from the early 19th century...

 

1508 Leonardo da Vinci sketched forms of contact glasses

 

1637 Descartes suggested corneal lenses

 

Thomas Young (1773-1829)

1801 Thomas Young fitted a lens to a cornea with a surrounding wax collar to retain fluid behind the lens, neutralising it and thus showing that the cornea was not involved in accommodation.

 

Young was one of those admirable if annoying polymaths who excelled in several fields. If only he had concentrated upon the corneal lens idea he might have invented contact lenses far sooner. Both a physician and a physicist he embodied the unique link between ophthalmologists and optometrists to be detected subsequently in this branch of optics. The year before he had moved into his late uncle's house in London and thus had the time and space to devote to his studies.

 

Three of the other subjects he investigated would find applications in twentieth century contact lens materials: The size of molecules, the surface tension in liquids and the elasticity of materials (which is still defined by Young's modulus). 

 

I take, out of a small botanical microscope, a double convex lens, of eight tenths radius and focal distance, fixed in a socket one fifth of an inch in depth; securing its edges with wax, I drop into the socket a little water, nearly cold, till three-fourths full, and then apply it to my eye, so that the cornea enters half way into it, and it is every where in contact with the water. My eye immediately becomes presbyopic, and the refractive power of the lens, which is reduced by water to a focal length of about 16 tenths, is not sufficient to supply the place of the cornea, rendered inefficacious by the intervention of the water; but the addition of another lens, of five inches and a half focus, restores my eye to its natural state, and somewhat more.

  

(From: A Course of Lectures on Natural Philosopy and the Mechanical Arts, published in two volumes, 1807. Available for study in the BOA Library).

 

Young discovered both that the cause of astigmatism and the fact that the cornea was not involved in accommodation. This diagram, when orientated the right way, shows Young's neutralising corneal lens mounted in a brass rim. It had to be used in this position to prevent the liquid from spilling.

 

1824 In Germany Franz Reisinger (1787-1855) mentioned the technique of corneal grafting suggesting its potential application from animal donor to human recipient. He also coined the term 'Keratoplasty' but the surgical solution was be delayed for the time being.

 

Sir John Herschel (1792-1871)

1827 Sir John Herschel suggested grinding a lens that conformed to the surface shape of the eye

 

Sir John, pictured here in old age, researched corneal irregularities and astigmatism, realising that neutralisation of the cornea in such cases could lead to an improvement in vision. He actually suggested making moulds of the eye with transparent animal jelly but we do not know if he ever tried to produce such a mould. Some early twentieth century historic articles refer to his gelatine moulds - but this could just be careless paraphrasing of the source material.

 

Should any very bad cases of irregular cornea be found, it is worthy of consideration whether at least a temporary distinct vision could not be procured, by applying in contact with the surface of the eye some transparent animal jelly contained in a spherical capsule of glass; or whether an actual mould of the cornea might not be taken and impressed on some transparent medium. 

    

(From: Light (1827) republished as Section XII 'Of the structures of the eye and vision' in the Encyclopaedia Metropolitana, 1845).

 

As Arthur Bennett wrote in his Optics of Contact Lenses (1949) it would appear that Herschel's idea was conceived directly from Airy's work on astigmatism using sphero-cylindrical spectacle lenses. Herschel evidently preferred a more direct form of correction and described his idea for a contact glass as the 'strict method'. The animal jelly would literally build up the surface of the cornea and the glass shell would be the means of retaining it in position.

 

The International Society of Contact Lens Specialists (ISCLS) was founded by three optometrists in 1954. The ISCLS has awarded the Herschel Medal since 1957 for outstanding services to contact lenses. The 2005 recipient was Donald Ezekiel, an optometrist from Perth, Australia.