The most common measurement made by optometrists throughout history is that of visual acuity. Every practitioner has a chart of some description which allows the patient’s acuity to be measured. We have seen the old-fashioned tried and true cardboard chart on the wall replaced by internally illuminated box-type charts, which in turn have been replaced by projector charts.

However each of these chart types has had its shortcomings. One problem has been the use of standardised charts in non-standard length rooms. For example a chart that has been designed to be used at exactly six metres will not give accurate measurements in rooms that are more or less than six metres long unless some mathematical consideration is given to the measured acuity. This has only been addressed by the more recent projector charts. Another shortcoming has been the problem of the patient memorising the letters, which has caused some corruption of all but the first acuity measurement of one of the patient’s eyes. None of the charts mentioned above can totally eliminate this problem. A third challenge to the accuracy of acuity measurement is standardisation of the chart’s illumination. Whether it’s the light that is cast upon the chart or the internal illumination of the chart itself, most practices have insufficient standardisation of this aspect and furthermore light bulbs inside charts are subject to change over time.

Enter the SmartChart Visual Acuity System. This instrument is the absolute state-of-the-art in Visual Acuity measurement. The chart is a high-contrast medical-grade LCD monitor with extreme sharpness on even the smallest of optotypes that can be used with the room lights on or off, so variation in brightness is no longer an issue and you never have to change another light bulb. It can be used in virtually any length of consulting room, either direct or viewed in a mirror and is easily recalibrated if the room configuration is changed. The influence of patient memory is totally eliminated by the ability to randomise the letters, but other optotypes including logmar, numbers, landolt C, illiterate E and easily recognisable symbols for children are also available to be used and randomised if desired. Masking is also possible by line or by letter.

But this is only the beginning. The SmartChart allows the practitioner to accurately test contrast sensitivity (in 10% steps), colour vision (38 Ishihara plates), fixation disparity and there is even a red / amber / green street light driving test as used in Europe. There are even schematic figures of the anatomy of the eye to assist in explanation to patients.

The SmartChart has also been designed to make life easy for practitioners. The system is preset to display the desired VA notation (metric, imperial, decimal, etc) with each size of optotype. It even allows sequence programming so up to three user-defined arrangements of tests can be programmed if desired. There is no need for an external computer to drive the chart as all processing is done internally in the chart itself. Only one power cable is necessary and the chart can either be wall-mounted or can sit on a table stand. The lightweight pocket-size remote control is powered by two AAA batteries - no need for a charging unit means no risk of being stranded with a dead remote control mid-patient.

The SmartChart LCD Visual Acuity System … exclusively available from Optical Manufacturers.

Lee J. Pepper
B. Optom (Hons)
April 2006