Purpose
Conventional fundus cameras are impractical for use with infants/children and with bedridden patients. Handheld fundus cameras are expensive, awkward to hold, and difficult to use to obtain good images. Indirect ophthalmoscopes with an integrated camera are better, but are also expensive and have cumbersome peripherals (external power/display, etc.). Moreover, the user needs to constantly look away from the viewing optics to see the display to ensure what is being captured is what is being viewed, and to manually adjust focus as needed. There have been descriptions of simply handholding a video camera (e.g., smartphone) and condensing lens, but both hands are needed and the technique needs to be learned. We propose a new method for an Indirect Ophthalmoscope Camera (IOC).
Methods
Our IOC uses a headband and mounts a digital camera with its display in front of the user’s dominant eye, with an eye loupe in front of the display for the examiner. The camera’s aperture acts as the only observation path, with the user examining the patient and composing the view directly on the display screen—so “what you see is what you get.” As a proof of concept, we leverage the iPhone 5’s high definition camera, bright LED light, and “Retina” display. The iPhone is mounted with the LED above the camera aperture and both are imaged by the condensing lens directly onto the patient’s cornea, centered within the pupil. The iPhone is set to video recording with continuous illumination.
Results
Using our IOC is as natural as using an actual indirect ophthalmoscope (e.g., head positioning, manipulation of the condensing lens to reduce glare, one hand being free). With autofocusing and autoexposure, the iPhone easily captured quality images of retinal hemorrhages, swollen optic nerves, fungus balls, and commotio in patients.
Conclusions
Our head mounted iPhone IOC is able to capture quality fundus videos during the indirect ophthalmoscopic exam of patients without the usual drawbacks described above. One disadvantage is that the exam itself is not stereoscopic. The videos captured are readily available for discussion with the patient and other providers. Our low-cost method should be easily adopted by ophthalmologists, as it preserves the way in which the indirect exam is performed.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)