Binocular indirect ophthalmoscopy using a standard fiberoptic surgical headlight.

Binocular indirect ophthalmoscopy may be performed in the operating room with a fiberoptic surgical headlight and condensing lens, eliminating the need for the indirect ophthalmoscope headpiece. The resultant aerial inverted stereo image has enhanced stereopsis but is otherwise identical to that obtained with the headpiece. Safe power settings for individual headlights can be determined with a photometer by measuring illuminance from a standard indirect ophthalmoscope and comparing this value to the intensities obtained at each voltage setting of the headlight. Illuminance from four different headlights was measured, and settings that yielded light output equivalent to the average indirect ophthalmoscope were designated for each headpiece. The maximum indirect ophthalmoscope illuminance values were averaged and found to be 2.0 watts/m2 (W/m2) for the 20-diopter (D) lens and 1.8 W/m2 for the 30-D lens. All of the headlights could be used at transformer settings that produced light intensities at or below the average maximum indirect ophthalmoscope illuminance. A stereoscopic image was obtained with each of the headlights, with both the 20-D and 30-D lenses. We conclude that standard fiberoptic surgical headlights may be used for stereoscopic fundus examination. The average maximal light intensity of fiberoptic surgical headlights is greater than that of the average indirect ophthalmoscope. However, each fiberoptic headlight can be operated at brightnesses equal to or below that of the maximum intensity of the indirect ophthalmoscope, and therefore, retinal toxicity is unlikely for brief retinal evaluations.