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Show J. Clin. Neuro-ophthalmol. 4: 57-58, 1984. Clinical Feature An Inexpensive Projectorlite for Visual Fields JAMES M. MITCHELL, M.D. Sophisticated, computer-assisted perimeters have become increasingly available in the past several years. Although they perform excellent quantitative visual field examinations, the cost of the automated perimeters places them out of the reach of many ophthalmologists. In particular, the Squid (Synemed Corporation) and the Octopus (Cileo Corporation) retail in the $70,000.00$ 90,000.00 range. I have recently corne across a hand-held ·perimeter,' which might appropriately be called ·the shrimp'-not only because of its small size, but also because of its small price (Fig. 1). This handheld, battery-operated projectorlite (Rowi International, Model 515) is typical of the inexpensive projectorlites which can be purchased in many photography stores* for around $8.25. It comes equipped with an arrow pointer bulb, which should be replaced with a 14 GE bulb or a standard 245 bulb ($0.90). The 14 GE and 245 bulbs produce a spot rather than an arrow. Two AA (lEe R 6 1.5 volt) batteries, which cost $2.00, are not included with the lightpointer. The projectorlite is used at the tanpent screen, as described by Dr. J. Lawton Smith. The examiner stands behind the patient and projects the light onto the screen, while one of the patient's • Brand's Camera, Inc., 84 South Ninth Street, Minneapolis, Minn. March 1984 eyes is covered, and the other eye is fixing on a tape cross (Fig. 2). The patient points to the light whenever it is seen. Every second or third ·shot" with the light can be placed in the blind spot, insuring adequate fixation. The light can be used for either static or kinetic testing, and the intensity of the light can be varied by partially covering the light with the examiner's fingers (Fig. 3). This technique can be used for rapid screening fields in the office, but it is also useful when seeing consults in the hospital. In the hospital, I simply tape a cross on the wall for fixation and perform the visual fields in the patient's room. If the patient cannot sit up, the cross is taped on the ceiling and the fields are performed with the patient supine. Although it may be argued that the background intensity cannot be controlled, and that the variable intensity of the light is not reproducible, with practice, ·shrimp· visual fields are quite reproducible and are especially valuable in patients who cannot otherwise undergo exhaustive perimetry. This inexpensive, portable projectorlite enables the ophthalmologist to perform visual field examinations in almost any setting. Reference 1. Smith, J,L.: Visual Fields 1-2. Neuro-ophthalmology tapes 57-58. 57 An Inexpensive Projectorlite Figure 1. The hand-held projectorlite. Figure 2. The examiner stands behind the patient during the visual field examination. Figure 3. To lower the intensity of the light, the examiner s fingers can be placed over the lens. Journal of Clinical Neuro-ophthalmology |
