The Dunscombe lens

With spectacles, instruments and other collectibles it is sometimes the case that they come along with a provenance and the item has more interest as a consequence of who owned it. Tim Bowden, peers deeper into the earliest 'British' contact lens...

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Timothy J Bowden FADO(Hons)CL FFDO (1952-2017)
Dispensing optician

The late Tim Bowden was an independent dispensing optician and contact lens practitioner in Kent. He was married to an optometrist and was the College of Optometrists' specialist co-adviser on the history of contact lenses from 2003-2017. His substantial book Contact Lenses: The Story was published in 2009. Tim was also the editor of the quarterly Ophthalmic Antiques from 2009-2017.

I came across an item in The Optician of 19th February 1937. It read:  

R. O. Dunscombe gave a talk on ‘Contact Glasses’ at a meeting of the Northampton and District local association Jan 28th 1937. He traced the history from the ‘crude celluloid shells of Herschel’ to the 'hard, resistant, finely worked products weighing less than 0.5grms and 0.5mm thick of the present day'. He talked about his own experiences when working on these lenses during his six months in Germany. (Author’s Note: Dunscombe was also a wearer). These glasses are capable of extremely good results not only in cases of Keratoconus but practically all cases of optical error, save only where lenticular astigmatism exists. (Presbyopic correction was either with over spectacles or reading Contact Glasses. Lenses could be made in Umbral glass to reduce glare).  

Neil Handley, curator of the BOA Museum, arranged contact for me with Peter Dunscombe. Peter was able to confirm that the person mentioned was his father....but reporters still got it wrong in 1937, as his father was not 'R.O'. but actually Kenneth Osmond Dunscombe! Kenneth had been born on 16th February 1909 in Bristol into the well-known Dunscombe optical family. His father Osmond William Dunscombe and grandfather Matthew William Dunscombe had both been presidents of the British Optical Association.

The Dunscombe lens beside its case
The Dunscombe Lens by the side of its case

Kenneth Dunscombe was educated at Clifton College and joined the family business in 1927. He qualified as an Ophthalmic Optician in 1930 or 31, having studied in the evenings, and went on to study at the University of Jena from 1932 to 33. Here he completed a thesis in German and developed an interest in what Zeiss was doing, particularly in the contact lens area. It appears he did some work with Carl Zeiss, Jena on the development of contact lenses and had one lens made for his own use (the subject of this article). Kenneth returned to the family firm comprising of four practices in and around Bristol. He was always very interested in technical innovation so it is quite possible he was fitting contact lenses in Bristol from 1933, as well as giving talks about them, but this is not confirmed. He was away from the practice for six years during the war serving as a Major in the 3rd Survey Regiment of the Royal Artillery. He saw action at Dunkirk and later in Egypt, Sicily and Italy and returned to ophthalmic practice afterwards. He retired fully in 1971 and died in January 2000.  

Zeiss made their first contact lenses in 1892 for Dr E. Sulzer of Geneva. Around 1912 Carl Zeiss adopted the trade name for such lenses of Auflageglas but changed to Haftglaser before 1920. Dr Wolfgang Wimmer of the Zeiss Archive in Jena advises that 'Auflegeglas' means ‘glass which is laid on’ whereas 'Haftglas' means ‘glass that is affixed, fastened’.

The Dunscombe lens is of clear ground glass and is in a black Zeiss case. The Carl Zeiss logo of an achromatic doublet that appears on this case was designed by Eric Kuithan and adopted on 24th June 1904. It remained in use by Zeiss Jena until the re-unification of the Zeiss companies in the 1990s.  

Zeiss contact lens case

The outside of the case shows the Carl Zeiss Jena logo in the form of an achromatic doublet lens. The case is also marked '275 / 9 +3.00'. With the Zeiss classification of fitting sets in 1932 this means the lens had a Scleral radius of 12.75mm, a corneal radius of 9.00mm and a power of +3.00D.

Measuring the parameters, using standard laboratory equipment, showed the corneal radius to be 8.90mm rather than the 9.00mm stated on the case. The Back Optic Zone Diameter was 13.00mm, Front optic zone diameter 13.00 mm showing a lenticulated front surface, the Overall size was 20.00 mm round, Central thickness 0.73mm and the Edge thickness to be 0.48mm. The transition on the back surface between the corneal and scleral curves was fairly sharp and the edges of the lens were smooth with no chips or starring but they were not well rounded. There were no markings on the lens and the weight, although not measured was possibly 0.5gms. A reading for the scleral radius could not be achieved.

The Power of the lens read +3.00D. Assuming an average Keratometry reading of 7.90mm this would make the liquid lens, trapped between the back of the lens and the front of the cornea, to be -5.00D. Therefore the spectacle prescription for Kenneth would be about -2.00D. Unfortunately we are not able to confirm that this is correct.

In August 1932 Dallos had been granted a patent in the US, number 1,869,366, assigned to Carl Zeiss, Jena, for the lenticulation of front surface of a contact lens to reduce weight of lens. The following year US Patents, numbers 1,921,971 and 1,921,972, were granted to Ferdinand Fertsch and Hans Hartinger again assigned to Carl Zeiss, Jena, Germany. These concerned the modification of a contact glass with a spherical transition curve or conical curve between that of the haptic and corneal parts to reduce the optic element and also the clearance required between the corneal surface and the back surface of the lens.

Dunscombe lens viewed sideways on

The Dunscombe lens exhibits the lenticulation but not the transitional curve. The evidence from the lens would therefore appear to be consistent with the provenance.

Zeiss supplied two fitting sets at this time but both were afocal using the liquid lens to correct power. The only other type of contact lens available at this time was the blown lens made by the Müller’s of Wiesbaden. This was reported as more comfortable with better wearing times than the Zeiss lens but generally it was less accurate and less reproducible. It was also less durable as the patient’s tears corroded the blown lens.  

The author would like to acknowledge the great help of: Peter Dunscombe, Neil Handley, Elisabeth Lowe, Richard Pearson and Dr Wolfgang Wimmer.  

The BOA Museum is most grateful to the Dunscombe Family for their generous decision to donate this important early British contact lens to its Contact Lens Collection.