Metrology Improving Global Ophthalmic Optics

Eyes are not only windows to the soul, but also the primary organ for accessing information from outside sources. About 75% of this critical information is obtained through our eyes.

With the social progress and the enhancement of life quality, people pay more and more attention to eye health. A study published by the World Health Organization (WHO) showed that there were about 28 million blind and visually impaired people worldwide and China accounted for about 18% of this total.

Ametropia, refers to vision disorders characterised by the eyes inability to correctly focus the images of objects on the retina, is the most commonly encountered issue with about 400 million people with glasses out of a population of 1.3 billion in China.  Aametropia can result in myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (lack of focus) and the need for glasses to correct people’s vision. 

Today, Chinese consumers don’t need to worry about the quality of glasses, but back in the 1980s, this was not the case. In 1988, the National Institute of Metrology (NIM) organised the first quality survey of glasses products in Beijing, but it turned out that the qualified accuracy rate of glasses tested were less than 30%. The causes included errors in optometry, degree of spectacle lenses, axis of astigmatism, framing, which seriously endangered the eye health of consumers.

In order to solve the quality problem of glasses products, NIM initiated a programme to improve metrology in field of ophthalmic optics. Focusing on various measuring instruments used in optometry, NIM endeavored to develop measurement standards for devices, formulate technical regulations and train local technicians. More than 2,000 provincial and municipal-level metrological institutions have been instructed to set up different levels of measurement standards in ophthalmic optics, and a national metrological traceability system for ophthalmic optics was established to conduct supervision and inspection of glasses products and ophthalmic optical instruments on the market. Since 1993, the quality of ophthalmic optical instruments, such as refractometers, focimeters and trial lens cases have been steadily improved with the qualified accuracy rate increased year by year to 92%, which has resulted in the increase of the qualified accuracy rate of glasses products on the market to more than 90%.

The various standard devices developed by NIM have been widely applied not only in domestic metrology institutions, quality inspection departments, enterprises and other units, but also in some well-known international manufacturers of ophthalmic optical products in Japan, France and the United States.

NIM also led the formulation of international standard of ISO 9342-2 2005 Test Lenses for Focimeters Used for Measuring Contact Lenses. In the field metrology for ophthalmic optics, NIM has established six national measurement standards, including primary standard of vertex power, working standard of vertex power of refractometer, working standard of vertex power of contact lenses, standard of central transmittance of lenses, standard of pupil distance meters and standard of ophthalmometers.

In addition, NIM has drafted about twenty relevant national standards and technical regulations. With the support of metrology systems and expertise, the domestic glasses industry has developed rapidly. Considering that more than 70% of glasses products in the global market are manufactured in China, hundreds of millions of ametropia patients all over the world have been significantly benefited from metrology

National Institute of Metrology, China (NIM), Dec. 2019