Ophthalmoscope History

The history of the ophthalmoscope is a beautiful episode that has been great for physiology. For centuries, men saw the eyes of animals and fellow humans as an organ that was so dark and impenetrable. It was only in the middle of the 19th century that much of the inner eye was seen with the discovery of the ophthalmoscope, a result of progressive research, findings and observations. Many innovations and improvements followed its discovery to make this instrument what it is today.

What is An Ophthalmoscope

• The ophthalmoscope is an instrument used to examine the eye and its interior, allowing eye specialists to determine it's health. Two basic types are direct and indirect. Direct is more commonly used, which is the size of a flashlight and has several magnifying lenses. The indirect has a hand-held lens and light attached to a headband, can be monocular or binocular, and provides a wider and better view of the inside of the eye.

Prior To The Opthalmoscope

• Several earlier findings led to the discovery of the ophthalmoscope. In 1810, it was explained light entering the eye from outside was why the eyes became luminous. In 1825, the inner portion of the eye was seen using myopic spectacles reflecting light into the eye from a candle behind the subject. In 1846, the red color of the luminous pupil was explained, as was the theory all eyes could be made luminous if the source of illumination directed towards a person's eye was in line with the observer's vision.

The Discovery

• A British subject, Charles Babbage, was the first to make an instrument for looking into the eye but when he could not get an image as he showed the instrument, he did not proceed further. Seven years later in 1851, the German inventor Herman von Helmhotz, desirous of explaining why the color of the eye was light at times and dark sometimes, discovered the ophthalmoscope using the same principles as Babbock.

Early Improvements

• The Helmholtz ophthalmoscope had concave lenses only, until a revolving disc with concave and convex lenses was introduced. In 1852, the indirect method was established. Many modifications and improvements followed. A refracting model was introduced in 1870, and in 1880, electric ophthalmoscopes were developed. In search of the ideal source of illumination, oil, petrol, gas, and daylight were tried. In1885, the first instrument using a bulb was made.

Later Improvements

• Ophthalmoscopes were mounted in stands for a long time until binocular indirect ophthalmoscopy came in 1947. Illumination with batteries and with incandescent bulbs came in hand-held sets. In the 1950s and 1960s, several direct ophthalmoscopes with excellent illumination were developed by the various manufacturers. The 3.5-volt halogen bulb further improved illumination, together with more complex and comprehensive models and options within models.

Modern Ophthalmoscopes

• Today's ophthalmoscopes mostly use halogen light for illumination. They are battery-operated and versatile. Apertures are varied: micro, small, and large spot sizes, fixation target, slit aperture, and focusing lenses with wide ranges. Some even have rubber brow rests that prevent scratching of eyeglasses. Prices range from $200 to as high as $2000 for those with binocular viewing and many complex options.