There are increasing numbers of patients for whom access to eye care is a problem. With well over a million people in the UK classified as housebound, the potential rise in unmonitored eye health is a significant problem. When the fact that the majority of these are elderly or physically or learning impaired, and therefore more likely to have related visual impairment or eye disease, the need for portability of useful eye health screening equipment is important.
A portable camera allowing accurate acquisition of clinical presentations is therefore something that should be welcomed in eye care practice.
Within practice too, however, the ability to transfer a camera from room to room, or simply to take it to the patient when it may be difficult for them to approach a desktop mounted camera system, is very useful.
It is also less likely to take up as much useful space in today's busy practice.
One such camera, the Nidek NM-200, was reviewed in a previous instrument focus (optician, July 22, 2004). We found it useful for external shots, and gave reasonable images of the fundus (Figures 1 and 2), even without dilation, with a somewhat restricted field of view. The portability of the instrument was, however, questionable as the weight of the base unit was little different to, say, a Pulsair NCT.
A more recent hand-held camera has been released, the Kowa Genesis D (Figure 3), and immediately strikes one as being light and compact. The camera offers excellent resolution and portability, but is clearly marketed as a mydriatic camera.
The Genesis D
The Kowa Genesis D weighs just over 1kg, making it very easy to hold and transport. It comes with a charging unit which is nearly 2kg, but, combined in their carrying case, the weight was still little of a challenge. When taking a sequence of images of a patient, the weight of the handset is important and fatigue and hand tremor can be a problem with heavier units. This instrument, however, was used for a whole afternoon session without any fatigue. The working distance for the camera is just 5mm from the eye and any camera shake would be alarming to a patient so, again, the light weight is an important feature.
The system is based around a 2 mega-pixel digital camera which offers an excellent resolution within that expected now for clinical images. The field of view achieved in the dilated eye is 30 degrees horizontal and 25 degrees vertical. Any gallant attempts by me to take an image in an undilated patient (possible with the NM-200) were thwarted and I imagine this might deter some practitioners who might be less willing to dilate. However, most are happy to dilate when clinically indicated and the camera therefore would be useful.
The handset is not too dissimilar to a large version of a Scalextric handset and the focusing dial is easily adjusted with the first finger while the thumb may depress the shutter button when the image in view needs to be captured. The focusing and shutter buttons are found on either side of the instrument so both left- and right-handed users should have no problem. Several of my colleagues tried the instrument throughout our afternoon trial and none failed to capture a decent image (a selection of which are shown in Figures 10 to 16).
The close working distance meant that every patient had to be warned of the proximity before any image was taken. It was also found to be prudent to warn the patients of the brightness of the flash. All, once warned, were quite happy with the procedure. The brightness of the flash was a reason why I decided not to capture an image of a photosensitive patient we were seeing that afternoon (with Stargardt's) - a coincidence, highlighting how not everybody is necessarily suited to such image capture.
Though the instrument does include a forehead pad or rest, it was actually easier to position one's own hand on the patient's forehead and guide the camera to the correct position. An image is viewed thorough the eyepiece just as with an ophthalmoscope. It is essential to focus the cross-hairs in the eyepiece prior to using the camera. The refractive error of the user, if not corrected, results in out-of-focus images. The eyepiece may be corrected from -15.00D to +3.5D.
The whole of the view is filled with the retinal image; a fine focusing of the image is carried out with a delicate flick of the focusing switch and, once one is happy with the image, the shutter is activated with the thumb. After several seconds the image captured appears on a small colour LCD screen on the side of the unit and it is then possible to decide whether to keep or delete it.
As one moves around the retina (there is no fixation track for a patient to follow, so the user has to scan around just as with an ophthalmoscope), the more peripherally one moves, the more focusing is needed. A +28D Volk lens attachment is available for the instrument for imaging the peripheral retina, though satisfactory images of the mid periphery were easily obtainable without this extra facility (Figures 4, 5 and 6). Figure 6 showed the extreme far periphery, without any supplementary lenses used, of a patient with lattice and laser scars. Though there is obviously some distortion, the lesions could still be visualised and captured.
Having limited access to slit-lamp capture equipment, I like the ease with which the system could be used to capture external and anterior shots (Figures 7 and 8). This also allows one, at the beginning of a photo session, to capture a shot of a record card or other identification to ease image storage identification and archiving (Figure 9).
The images, as with any digital camera, are easily transferred into a computer system running any imaging or indeed patient management software. I used a USB link to my laptop, but, equally could have taken the flashcard out of the system and transferred the images via a PC card port. Prior to transfer of data, the images captured during any session may be easily reshown on the screen on the side of the camera itself. Any unsuited may be deleted at this point to ease future image administration.
I have to say I was impressed by this instrument. Its portability, ease of use, quality of capture and ease of data manipulation and transfer are all commendable. Priced at 9,500, the Genesis is to be recommended to anyone unafraid to dilat