Smartphones with high-quality cameras and high-resolution video are being used for retinal imaging. Lord et al.[1] published the first report on the use of smartphones for fundus imaging. Smartphone fundus photography has been performed by dangling it to the eyepiece of a slit lamp and focusing the retina using a 90 D condensing lens. But this method requires a great deal of focus and hand stability, and it is difficult to capture fundus images with it.[2]
Here, we describe a novel method of performing fundus photography with a universal slit-lamp–mounted mobile and a 20 D lens adapter made from trash, which can help primary care physicians or ophthalmologists at primary/secondary centers to take fundus photos for digital analysis by retina specialists across the world.
Innovation
The adapter was made out of a plastic sanitizer bottle [Fig. 1]. The materials required were 1) 20 D double aspheric lens, 2) smartphone adapter, 3) sanitizer bottle, 4) half-inch-broad iron plate, and 5) smartphone.
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Figure 1: Step-by-step guide to make universal slit-lamp–mounted fundus camera with a 20 D lens at one end and smartphone at another end. Take a sanitizer bottle (a) of 18 cm length with one end of 6.3 cm diameter to hold a 20 D lens (b) and the other end of 1.8 cm diameter with neck to hold a mobile adapter (c). Then, take a broad iron plate and mold it to take the shape of two “U”s of diameter 8 cm each (d). Attach it to a 15-cm-long horizontal plate, which itself is attached to an L-shaped plate with a screw at its end (e). Finally, fix this mold on any slit-lamp biomicroscope at its hinge point using a 10-size screw (f)
Preparation of Cam: A sanitizer bottle of 18 cm length was taken with one end of 6.3 cm diameter to hold a 20 D lens and another end of 1.8 cm diameter to allow the camera to take pictures. So, one end was cut to accommodate a 20 D lens and other end was prepared with neck to hold mobile adapter as shown in Fig. 1. Edges of this bottle were smoothened with sandpaper, and a 20 D lens was inserted at one end. Standard size mobile adapter was attached to hold the mobile in place and align it with a sanitizer bottle aperture at the other end as shown in Fig. 1a–c.
Preparation of iron frame: Broad iron plate was molded to take the shape of two “U”s of diameter 8 cm each, attached to a horizontal plate (15 cm long), which itself was attached to an L-shaped plate with a screw at its end. Fig. 1 depicts the step-by-step making of this frugal innovation. This mold could be fixed on the slit lamp at its hinge point using “10 size screw” (threads of screw were grounded well to get smooth finishing). The steps have been depicted in Fig. 1d–f.
With professional help, the mount was made with custom-made anchoring bolt, giving a better appearance and stability to the device. It was then used like a fundus camera using the joystick with the camera in the continuous flash-on mode. Sponge was used on Us to hold the sanitizer bottle in place. This whole unit was mounted on a slit lamp; the patient was asked to sit comfortably, place his/her chin on chinrest, and touch his/her forehead to headrest. Using mobile flash, fundus pictures were taken. Fig. 2 shows a few photographs taken with the help of this device.
Figure 2: Few fundus photographs taken by universal slit-lamp–mounted fundus camera with a 20 D lens at one end and a smartphone at another end, showing (a) central serous chorioretinopathy, (b) intravitreal dexamethasone implant, and (c) myelinated nerve fiber
Discussion
Smartphone fundus photography using a 20 D condensing lens has been performed where the examiner holds the smartphone in one hand and 20 D lens held in another hand near the patient’s eye. The filming distance is adjusted by moving the lens or mobile forward or backward to a point the fundus is focused and fills the full area of condensing lens on the smartphone display screen.[3-5] But it is a herculean task with a learning curve, especially for beginners, to do maneuvers to adjust filming distance and glare from the condensing lens and focus fundus image in busy ophthalmology outpatient departments (OPDs).[3-5]
Our innovation can be mounted on any slit lamp with fixed stable filming distance and a compartment to hold a 20 D lens at a measured distance and co-axial with the camera lens to capture fundus images. This innovation allows a separate channel for ocular examination and fundus photography on a slit-lamp itself, without compromising on the binocular viewing system, and allows for sharp focusing with binocular ocular resolution. This universal mounted scope can become daily means of quick documentation, tracking and follow-up of patients, patient education, and can help in research.
Smartphones are now available everywhere, including primary care centers and remote areas and in situations of emergency, to obtain advice from tertiary centers. They are, therefore, very useful and one can get good-quality images for consultation and diagnosis. This frugal innovation also avoids financial investment and does not require upkeep; it is suitable for primary or secondary setups. Thus, this device is a feasible and cheaper option made with commonly available materials on the “do-it-yourself” concept for fundus photography.
Conclusion
This do-it-yourself innovation of universal slit lamp–mounted mobile adapter with 20 D lens is a feasible and easy-to-install device for fundus photography, which can record and capture fundus images. Therefore, it is of immense help in quick digital analysis by retina specialists across the world, along with reducing the need for unnecessary referrals to tertiary eye care centers.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
1. Lord RK, Shah VA, San Filippo AN, Krishna RJO. Novel uses of smartphones in ophthalmology. Ophthalmology 2010;117:1274.e3.
2. Haddock LJ, Qian C.
Smartphone technology for
fundus photography. Retin Phys 2015;12:51–8.
3. Haddock LJ, Kim DY, Mukai S. Simple, inexpensive technique for high-quality
smartphone fundus photography in human and animal eyes. J Ophthalmol 2013;2013:518479.
4. Chandrakanth P, Ravichandran R, Nischal NG, Subhashini M. Trash to treasure Retcam. Indian J Ophthalmol 2019;67:541–4.
5. Raju B, Raju NS, Akkara JD, Pathengay A. Do it yourself
smartphone fundus camera–DIYretCAM. Indian J Ophthalmol 2016;64:663–7.
