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A. M. Kolomeyer, B. C. Szirth, W. Su, K. Shahid, L. Dordai, A. Khouri, N. Bhagat; The Use of LED Illumination in High-Definition Tele-Stereo Slit Lamp Biomicroscopy. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1022.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate anterior segment ocular images using LED illumination source in slit lamp biomicroscope and to compare them to images obtained using Tungsten (Tg) bulb illumination (the standard source of illumination in slit lamp biomicroscopy). Tg bulbs waste 90% of their energy and emit potentially harmful UV and IR wavelengths causing high thermal irradiance during dynamic video eye imaging. LED illumination source produces virtually no heat and is much more efficient (250 lumens per watt (lm/w)) than the Tg bulb (16 lm/w). These characteristics result in a more comfortable session for the patient during ocular imaging.
Static and dynamic video images were captured using a Haag Streit BQ slit lamp biomicroscope equipped with a dual 100% port beam splitter and a high-definition (HD) 1080 progressive scan CCD from IntraVista systems (San Francisco, CA). Temperature measurements at the source of illumination and at the skin and sclera were obtained. Images were reviewed by an ophthalmologist for clarity and color detail on a 22 inch stereoscopic interlaced display using stereo 3D shutter viewing glasses. Surface irradiance was measured using a SPI infrared RAZ-IR detector (Las Vegas, Nevada).
Clarity of details along with true hue and life like colors of anterior segment structures on 35 individuals using the LED images were superior to the ones obtained by the Tg bulb. After a five minute interval, the temperature of the Tg bulb increased by 63.5oC and LED by 2.8oC; the temperature of the Tg illumination housing rose by 15.3oC, while the LED did not increase; and the temperature of the Tg junction connector rose by 40.1oC and LED by 2.9oC. Skin temperature increased by 10.3oC and sclera by 4.6oC after Tg exposure, while there was no change in skin or scleral temprature using LED illumination.
The LED light source is an attractive alternative to the Tg illumination since it has a longer life expectancy (30,000 hours vs. 100 hours), creates minimal heat that translates to patient comfort and cooperation during examination or live tele-video transmission, includes IR and UV barrier filters that result in a truer color appearance, and can also endure impact during use since there are no filaments. The HD 3D viewing capability has applications in tele-ophthalmology and in medical training.
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