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BRIEF COMMUNICATION
Year : 2022 | Volume
: 12
| Issue : 4 | Page : 462-464
Virtual-reality headset mounted smartphone-based Indentation fundus videography
Deependra Vikram Singh1, Sandhya Gaur1, Raja Rami Reddy2, Ajay Sharma1, Yog Raj Sharma3
1 Vitreoretinal Services, Eye-Q Superspecialty Eye Hospitals, Gurugram, Haryana, India
2 Vitreoretinal Services, Neo Retina Institute, Hyderabad, Telangana, India
3 Dr. R.P. Center for OS, AIIMS, New Delhi, India
Correspondence Address:
Dr. Deependra Vikram Singh
Eye.Q Superspecialty Eye Hospitals, Gurugram - 120 009, Haryana
India
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/2211-5056.355559
To describe a simple and novel technique that overcomes the limitation of smartphone-based fundus photography and allows examiners to capture peripheral retinal images with indentation. Smartphone with video camera in flash-on mode was mounted on virtual-reality (VR) headset. This was combined with +28D lens and +20D lens and soft cotton bud to capture high-quality videos of peripheral fundus with indentation. Autofocus function of the camera and examiner's head movements to adjust the distance was used to obtain retinal video. The procedure is akin to indirect ophthalmoscopy. The feasibility of obtaining well-focused retinal images during indentation was checked. We could obtain good quality videos demonstrating indentation of the peripheral fundus in 10 eyes showing different pathologies such as laser marks, lattice degeneration, and pigmented lesions. VR headset-mounted smartphone-based indentation fundus videography is an innovative cost-effective technique to capture peripheral retinal images. The technique can be useful for documenting retinopathy of prematurity lesions and other situations where widefield photography is not possible.
Keywords: Fundus imaging, indentation videography, peripheral retinal imaging, smartphone
Smartphone-based fundus photography has become increasing popular due to its portability and cost-effectiveness. The principle of smartphone fundus photography is based on indirect ophthalmoscopy using 20D or 28D condensing lens and utilizing the flash of smartphone camera. Following the initial description by Haddock et al.,[1] a lot of researchers have added further modifications such as integrated lens adaptors[2] to either make it more convenient for users or to allow wide-angle viewing.[3] Although Kim et al.[4] and Hong et al.[5] have demonstrated the safety of retinal irradiance from flashlights generated by previous iPhones, the same needs to be validated for newer ones.
Reviews by Iqbal[6] and Raju and Raju[7] have listed quite a few challenges faced by beginners who intend to learn this technique. They have also suggested few modifications such as adjusting the distances, using a 28D lens, and smartphone apps such as Ullman indirect. Some holding devices are also available but they still require hand stability and lots of practice from the examiner. Smartphone photography has found to be particularly useful for documenting retinopathy of prematurity (ROP) where conventional noncontact wide-field photography is impractical and RetCam imaging not widely available due to prohibitive cost. Conventional smartphone photography does not allow retina surgeons to indent sclera and examine the peripheral retina. We report in this study a novel technique where smartphone was mounted on VR head-mounted device (VR-HMD) to allow us scleral indentation during videography. The technique and its merits are discussed.
Materials and MethodsThis study was approved by the institutional review board at the ethics committee (EC) Eye-Q Vision Pvt. Ltd (Protocol # ECEQ/22/004, V001 February 23, 2022). Informed consent was obtained from all the patients or their guardians before subjecting them to this novel imaging technique. Smartphone videos were captured by an Apple iPhone 13 pro mounted on an Irusu Mini VR, a VR-HMD device from Irusu® Hyderabad, India. VR-HMDs have high-powered wide diameter 44-mm HD resin lenses that allow the user to view screens placed very close to the eye. A lot of VR-HMDs are now commercially available. We choose a VR-HMD that keeps the camera of the mounted smartphone uncovered and exposed for capturing a video. [Figure 1]a shows the smartphone mounted on VR-HMD where one can notice that camera is exposed for capturing. [Figure 1]b shows the high-powered lenses of VR-HMD. [Figure 1]c and [Figure 1]d show a retinologist using VR-HMD with smartphone and 28D lens for capturing high-resolution videos of the peripheral retina. The wide-field photography is done after dilatation of the patient. The basic method and principles of smartphone photography were the same as described elsewhere.[1],[6],[7] The camera of iPhone 13 pro is switched on and shifted to video mode with flash turned on before mounting it to VR-HMD. Surgeon wears this VR-HMD on their head and then uses a 28D or 20D lens in his dominant hand to focus retinal images. Surgeon has to realize that the fundus view from VR-HMD is monocular so he has to use one of the eyes for focus while keeping the other eye closed. The video camera can be turned on by a remote switch. The nondominant hand of the surgeon is free and can be utilized for scleral indentation and thus allowing imaging of the peripheral lesions. All videos were captured after full dilation of the pupil. We restricted video length to less than 30 s for all patients to avoid overexposure of flash and also avoided capturing the posterior pole. All the lesions were detected and localized by indirect ophthalmoscopy first and then video graphed by this smartphone-based technique. This reduced the duration for which the retina was exposed to flashlight from phone. All patients except the premature infant with ROP were reexamined after 2 weeks and 6 weeks intervals to record their best-corrected visual acuity (BCVA) and fundus autofluorescence (FAF) imaging to look for any adverse effect of exposure to flashlight from smartphone.
Figure 1: (a) Representative photograph showing inventory required for smartphone-based indentation fundus videography. One can see iPhone 13 pro mounted on VR headset and remote switch for the device (black arrow). The flash of camera is on and the camera is exposed to allow capturing of videos (white arrow). (b) Representative photograph showing high-powered HD lenses of VR headset. (c) Representative photograph showing examiner holding +28D lens in dominant (right) hand and using soft cotton bud in nondominant hand for indentation. (d) Representative photograph showing smartphone in flash-on mode mounted on VR headset while the examiner is using both hands to capture fundus videos with indentation. VR: Virtual-reality Results We used this technique to capture videos of the peripheral retina in 10 eyes of 10 patients with different retinal lesions. [Figure 2]a, [Figure 2]b, [Figure 2]c, [Figure 2]d shows few stills extracted from videos showing indentation videography on eyes with ROP, lasered lattice, and a pigmented lesion. The quality of images and videos was found to be good and adequate to detect and document the retinal pathology as confirmed by all four coauthors. We also did not observe any adverse effect on BCVA or FAF in the nine eyes that were reexamined at 2 and 6 weeks following this smartphone-based videography. Two 30-s movie clips are provided as supplemental material to demonstrate the indentation during continuous fundus video recording and a 75-s movie clip to show the mounting technique [Video 1-3]. https://vimeo.com/678988481, https://vimeo.com/678989178, https://vimeo.com/705879175/5d6e4ea7e6.
Figure 2: (a) Still photographs from smartphone videos showing both hands of the examiner being used for indentation fundus videography. (b) Still photograph from smartphone video showing laser marks over indentation (white arrow) in an infant with retinopathy of prematurity. (c) Still photograph from smartphone video showing lasered lattice nicely visible over indent (white arrow). (d) Still photograph from smartphone video showing a pigmented lesion (white arrow) over indent in peripheral retina of a 32-year-old female Discussion Wide field fundus photography allows us to document the peripheral retinal lesions that are detected on indirect ophthalmoscopy. However, the high equipment cost of wide-field photography devices is prohibitive for most retina practices and cameras mounted on video indirect ophthalmoscopes are either bulky or very expensive. VR headset-mounted smartphone-based peripheral indentation videography described by us is a simple inexpensive technique that not only allowed us to document peripheral retinal lesions but can also serve as a good educational tool for retina fellows intending to learn scleral indentation. The benefit of using VR headset is its 44-mm HD resin lens that allowed us to view the phone placed very close to our eye. This combination makes the procedure akin to indirect ophthalmoscopy. There was no image distortion in periphery noted but one does get abnormal light reflexes during the examination. The +20D condensing lens can be tilted to reduce these disturbing reflexes. Since retinal surgeons are well-versed with indirect ophthalmoscopy and are used to make head adjustments to get a clear focus of retinal image, a head-mounted device offers a great advantage and short learning curve for smartphone-based fundus photography to them. Three things would influence the field of view and magnification from this videography; whether the lens used was +20D or +28D, the refractive status of the eye examined and distance between the observer and the eye. This technique allowed us to document procedures such as indentation and cryopexy which was not possible earlier. Other advantages of this technique are its portability and compatibility with all smartphones that can have continuous video recording with a flashlight. The limitation of this technique is the monocular view and limited data on safety of flashlight of the newer smartphones. However, even after two decades of smartphone fundus photography, we could not find any report of retinal phototoxicity from flashlights in the literature. Furthermore, the precautions observed by us like limiting the video duration to 30 s and avoiding capture of the macula can reduce the risk of phototoxicity. The adjustments such as using the Ullman indirect app or applying micropore tape to flashlight to reduce the intensity of flashlight can also make this technique even safer.[1]
ConclusionIndentation fundus videography by VR-HMD mounted smartphone is a simple and cost-effective technique to document peripheral retinal pathologies. We could not find any evidence of phototoxicity from this technique at the 6-week follow-up.
Financial support and sponsorship
Nil.
Conflicts of interest
The authors declare that there are no conflicts of interests of this paper.
References
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