Catalogue Number: 1688
Atago CL-1 Contact Lens water content refractometer
Sub-Category: Contact lens equipment
Designer/inventor: EFRON, Nathan, BRENNAN Noel
Year Of Publication/Manufacture: c 1988
Time Period: 1940 to 1999
Place Of Publication/Manufacture: Japan
Description Of Item: Refractomer adapted for the measurement of water content of hydrogel contact lenses. Single adjustable eye piece, sample holder with flip up cover. Marked on flip up cover 'Atago CL-1 Contact Lens Water content 35.80 % Made in Japan'. Engraved by previous owner 'V.C.O. Unit 2' Contained in a blue vinyl covered box 128 L x 73 w x 52 H mm with push stud fastener on fold up and out lid, cut foam packing inside. Box marked 'Atago Hand Refractometer' and in 'VCO Unit 2 Clinicians Room' in marker pen ink.
Historical Significance: The use of a hand-held Abbe refractometer for measurement of water content of hydrogel contact lenses was first described by Nathan Efron and Noel Brennan [Efron N, BrennanNA. The soft contact lens refractometer. Optician 1987:194: 9-41.] The Atago CL-1 Soft Contact Lens Refractometer is the commercial development of this application of the Abbe refractometer as specifically designed for measuring the water content of hydrogel contact lenses. Ernest Abbe's (1840-1905) refractometer is based on the measurement of the critical angle at the interface between a sample and a prism of known index of refraction and uses white light. As the refractive index of some materials is related to their water content, the handheld Atago CL-1 Soft lens Refractometer has been calibrated to provide a reading of the percentage of water content of soft contact lenses.
How Acquired: Donated by ACO Optometry Clinic
Date Acquired: Nov 2010
Location: Archive room. West wall. Unit 6 Drawer 2