Abstract
Purpose. Nonmydriatic fundus cameras allow retinal photography without pharmacologic dilation of the pupil. However, currently available nonmydriatic fundus cameras are bulky, not portable, and expensive. Taking advantage of recent advances in mobile technology, we sought to create a nonmydriatic fundus camera that was affordable and could be carried in a white coat pocket. Methods. We built a point-and-shoot prototype camera using a Raspberry Pi computer, an infrared-sensitive camera board, a dual infrared and white light light-emitting diode, a battery, a 5-inch touchscreen liquid crystal display, and a disposable 20-diopter condensing lens. Our prototype camera was based on indirect ophthalmoscopy with both infrared and white lights. Results. The prototype camera measured 133mm × 91mm × 45mm and weighed 386 grams. The total cost of the components, including the disposable lens, was $185.20. The camera was able to obtain good-quality fundus images without pharmacologic dilation of the pupils. Conclusion. A fully functional, inexpensive, handheld, nonmydriatic fundus camera can be easily assembled from a relatively small number of components. With modest improvements, such a camera could be useful for a variety of healthcare professionals, particularly those who work in settings where a traditional table-mounted nonmydriatic fundus camera would be inconvenient.
Highlights
Evaluation of the fundus is an essential component of an eye examination, providing valuable diagnostic information to both ophthalmologists and nonophthalmologists
The prototype nonmydriatic fundus camera and condensing lens can be seen in Figures 1 and 2
With the fundus camera in one hand, and the condensing lens in the other, the user performs infrared indirect ophthalmoscopy. This is similar to the mydriatic smartphone fundus photography technique described previously [1]
Summary
Evaluation of the fundus is an essential component of an eye examination, providing valuable diagnostic information to both ophthalmologists and nonophthalmologists. Our group has recently published on using smartphones combined with handheld indirect lenses for mydriatic fundus photography [1]. This technique offers the advantages of being both inexpensive and portable compared to most current methods of fundus photography. Regardless of specialty, pharmacologic dilation tends to be inconvenient for both the medical practitioner and the patient, with the dilating drops taking about twenty minutes to take effect and the patient experiencing blurred vision and light sensitivity for up to several hours after dilation. Pharmacologic dilation prevents subsequent physical examination of the pupils for several hours, an effect that can be undesirable when monitoring inpatients with critical neurologic disease. There is a small but real risk of inciting acute angle-closure glaucoma in susceptible eyes with the use of dilating eye drops [2]
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