New diagnostic method for visual grading

Víctor Rodríguez

Instituto de óptica "Daza de Valdés" (IO-CSIC), Spain

In the eye, the cornea and the lens help to focus light and ensure correct vision. At times, however, refractive errors – better known as myopia, hyperopia, astigmatism presbyopia and so on – can occur, leading to vision problems. These problems are usually caused by the shape of the eye, such as the length of the eyeball, changes in the cornea or an ageing lens. Seven out of ten people suffer from some form of refractive error worldwide and these problems affect 100 % of the population over 50 years of age.

At present, there are several methods for diagnosing vision problems. The method preferred and most commonly used by opticians and ophthalmologists is known as subjective refraction. In it, the practitioner tests different lenses on the patient until maximum possible visual acuity is achieved. Although this method is laborious, time-consuming and sometimes not wholly accurate, and quicker technologies for estimating refractive error (visual acuity) exist, based on the characteristics of the eye, these have not replaced the traditional method, which has hardly changed in the last 200 years. The reason for this is that eyecare clinicians still prefer the subjective information – known as direct subjective refraction – that patients provide.

In response to this, the researchers have developed a new method of subjective refraction diagnosis based on adjustable lenses and using the chromatic aberration of the eye to evaluate refractive error. This method reduces measurement time and increases precision, and the project aims to develop its full potential and validate it in clinical studies.