How To Get The Best Fovea Photo With A Fundus Camera

• Journal List
• J Vis Exp
• (125); 2017
• PMC5609317

J Vis Exp. 2017; (125): 55958.

Smartphone Fundus Photography

Hossein Nazari Khanamiri

^oneDepartment of Ophthalmology and Visual Sciences, University of Texas Medical Branch

Austin Nakatsuka

¹Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch

Jaafar El-Annan

^oneSection of Ophthalmology and Visual Sciences, University of Texas Medical Branch

Abstract

Smartphone fundus photography is a simple technique to obtain ocular fundus pictures using a smartphone camera and a conventional handheld indirect ophthalmoscopy lens. This technique is indispensable when picture documentation of optic nerve, retina, and retinal vessels is necessary but a fundus camera is not available. The main advantage of this technique is the widespread availability of smartphones that allows documentation of macula and optic nervus changes in many settings that was non previously possible. Post-obit the well-defined steps detailed here, such every bit proper alignment of the phone camera, handheld lens, and the patient'southward pupil, is the cardinal for obtaining a articulate retina picture with no interfering lite reflections and aberrations. In this paper, the optical principles of indirect ophthalmoscopy and fundus photography will be reviewed showtime. Then, the stride-by-step method to record a good quality retinal image using a smartphone will be explained.

Keywords: Medicine, Issue 125, Smartphone, Fundus photography, Retina, Optic nerve, Ophthalmoscopy, Indirect Ophthalmoscopy, Fundus photographic camera, Handheld plus lens

Introduction

Fundus photography is the standard method for documenting ocular fundus findings. Fundus photography is traditionally performed in a clinic setting using a fundus photographic camera. Even so, fundus cameras are not available in many situations including in emergency rooms or on hospital floors where documentation of the retinal changes may be necessary. Indirect ophthalmoscope-mounted and handheld contact and non-contact fundus cameras are alternative ways to document retinal images, but availability and high cost limit their day-to-day utilise in most ophthalmology practices. Smartphones equipped with high-resolution cameras are increasingly being used for anterior segment and retinal imaging in ophthalmology.1,2

In smartphone retinal imaging, the smartphone camera'southward coaxial flashlight and a handheld high plus power lens create an indirect ophthalmoscopy-similar optical arrangement that is able to record high resolution digital retinal images (Figure i).3,4,5,6,7 Smartphone adaptors for such retinal photography are commercially available from multiple companies3 and educational videos are publicly available to teach how to obtain retinal images using smartphones and these products. However, smartphone retinal photography does not necessarily need such adaptors. Here, we intend to teach how to record a adept quality retinal image with a smartphone and tools readily available in an ophthalmology practice.

With increasing availability of smartphones and the expansion of telemedicine, this method can be adapted by ophthalmologists and optometrists to certificate retinal pathologies in emergency room settings and telemedicine consultations. In improver, health care providers may find this method useful in developing countries and in medical aid camps during a disaster rescue functioning. Like any new technique, mastering smartphone retinal photography needs practice.8 The following protocol volition explain detailed steps for smartphone photography. Optical basis of the technique will be discussed in the next department. Technical and operational constraints such equally image resolution, field of view, and patient privacy and confidentiality will be discussed in the cease.

Protocol

Ensure that fundus photography in the protocol follows the guidelines of your institutes human research ethics commission.

Note: Smartphone retinal imaging, like conventional indirect ophthalmoscopy, should be performed through a dilated student. A strong smartphone camera flash light is crucial to obtain a articulate fundus picture, especially with mild to moderate media opacity. Make certain to exercise the method on a model eye or on peers before attempting to examine the patient. Patient cooperation is a key for adept smartphone fundus photography.

i. Smartphone Retinal Imaging

1. Explain the procedure to the patient and obtain permission. Explicate that the process may take i - 2 min and involves shining a vivid light into the heart.

2. Amplify the patient'southward pupil using a combination of mydriatic drops such as 2.5% Phenylephrine and 1% Tropicamide ophthalmic drops (i driblet from each, two - three min autonomously, in the centre to be examined). Wait xv - 20 min for pupils to dilate.

3. Sit down in front of the patient on a comfortable chair and be positioned thirty - 60 cm from the patient and at about the same level (Effigy 2).

   

4. Inquire the patient to look at a far target with the other center.

5. Set the smartphone camera on video mode.

6. Plow on the camera's flashlight.

7. After darkening the room, printing the photographic camera record button on the smartphone to tape a continuous video.

8. Concord the +20 diopter (D) or any other indirect ophthalmoscopy lens in front of the patient'southward eye with your thumb and index finger. Utilise the middle and ring fingers to stabilize the paw and lens and to assist go on eyelids open.

9. Concur the photographic camera ten - 35 cm from the lens. Direct the camera along the patient's pupillary centrality. Aim the light to the pupil and find the retina glow. Direct the light through the lens onto the retina and continue video recording.

10. While recording, move the photographic camera and the lens to find a good focus and an image complimentary of lite reflections. Conform the handheld lens to and from the patient's eye to meet a articulate retina paradigm filling the unabridged lens area. NOTE: In our experience, the lens should exist held three - 5 cm from the eye (this is slightly further away from the cornea surface compared to what is appropriate for an indirect ophthalmoscopy exam).

11. Endeavour to eliminate unnecessary low-cal reflections by adjusting the camera and lens positions. Losing the epitome while searching the retina means that the camera and its flash lite are not aligned with the handheld lens and educatee. It takes exercise to keep the photographic camera, handheld lens, and patient pupil aligned.

12. Continue to record video until a good view of the expanse of interest without significant light reflections and aberrations is captured.

13. Cease the recording and ask the patient to sit dorsum and be comfy.

14. Re-play the recorded movie until there is a good retina view within the handheld lens area. End the picture show and have a screen shot of the view (Figure three).

    

15. Magnify the screen shot and take another screen shot for a larger retina image (Figure three). Similar an indirect ophthalmoscope view, this paradigm is inverted.

Representative Results

The optics of fundus imaging using a smartphone camera is similar in principle to retina test with indirect ophthalmoscope (Figure 1).nine In an indirect ophthalmoscope, a beam of light is directed toward the patient'southward retina and the reflected rays off the retina are condensed to a real aeriform image using a handheld +15 - +30 D lens (Figure 1). The viewer sees the real, inverted aerial image that is located 2 - 4 cm from the handheld lens, depending on the power of the lens. With a smartphone, the camera'due south flashlight replaces the indirect ophthalmoscope calorie-free source and the smartphone camera recording the aerial paradigm replaces the observer's eye. Conventional fundus cameras are also designed based on the same optical principles; the camera'due south picture or digital sensor array is located where the aerial epitome is formed.

The portability of smartphones makes smartphone retinal imaging a promising technique for emergency rooms, telemedicine consulting, and retinal disease screening programs. Ii representative images (Figure 4 and Figure 5) are recorded in emergency room and hospital floor consultation settings.

Figure ane : Optics of Indirect Ophthalmoscopy and Smartphone Fundus Photography. Schematic drawing shows the viewing system of an indirect ophthalmoscope (A) and fundus photography using a smartphone (B). Delight click here to view a larger version of this effigy.

Figure ii : Examiner and Patient Positioning for Smartphone Fundus Photography. The examiner sits in front and slightly to the side of the patient and holds the smartphone in one paw and the handheld lens in another hand well-nigh an arm length distance from the phone. Please click here to view a larger version of this effigy.

Figure three : A Normal Macula and Optic Nerve Imaged Using a Smartphone. Please click here to view a larger version of this figure.

Figure 4 : Nonproliferative Diabetic Retinopathy Imaged Using a Smartphone. Annotation flame-shaped and dot and blot retinal hemorrhages. Delight click here to view a larger version of this figure.

Figure 5 : Nonarteritic Anterior Ischemic Optic Neuropathy Imaged Using a Smartphone. Annotation the blurring of optic disc margins in this image. Please click here to view a larger version of this effigy.

Discussion

The quality of fundus images taken by smartphone could be comparable to that of fundus cameras. In one comparison study of fundus images taken past smartphones and fundus cameras, masked reviewers did not find a meaning deviation.8,10 In the same study, the quality of fundus images was college when images were captured by more experienced examiners compared to junior examiners.viii

Smartphone fundus photography may appear a challenging technique in the commencement. Yet, like any other examination technique, mastering the technique needs practise and the process of smartphone imaging of the retina becomes routine with time. A item challenge is related to the location of smartphone cameras and their screen. Nearly smartphone cameras are located at the corner of the phone while the screen to view and focus the prototype is at the centre. A beginner should focus on mastering coordination betwixt filming and lens easily and proper alignment of the phone, handheld lens, and the pupil axis.

Flashlight intensity cannot be adjusted within nigh smartphone camera settings. However, one may dim the light intensity by applying a semitransparent adhesive tape over the light source. Alternatively, filming interface apps may help adjusting the camera calorie-free intensity. Multiple smartphone apps are available that permit adjusting exposure, focus control, and flashlight intensity.4 While non an accented requirement for smartphone fundus photography, examiners may find these filming/epitome taking interfaces helpful in improving the quality of their images.

The field of view varies with the diopter forcefulness of the handheld indirect ophthalmoscopy lens. Lower power lenses (such as +xv D or +20 D lenses) provide a smaller field of view with higher magnification.

The confidentiality of personal data in accordance with Wellness Insurance Portability and Accountability Act 1996 (HIPAA), the Data Protection Act 1998, and Access to Health Records Deed 1990 is a disquisitional effect when using personal cameras to record health information. Nosotros take still retina pictures inside our institute'south electronic medical record (EMR) app that allows recording and transferring confidential patient images. Using dedicated cameras, encrypted phones, and HIPAA compatible email services are mandatory in many institutes for protecting patient privacy.

Smartphone fundus photography is a safe technique. Kim et al. showed that iPhone 4 photographic camera flashlight is ten times less luminous than a conventional indirect ophthalmoscope light.xi While this may offering more comfort for patients during imaging, it limits prototype clarity in the presence of moderate to pregnant media opacity. In the same report, the low-cal levels of the smartphone lite source were 150 times beneath the limit set by the International Organisation for Standardization (ISO 15004-2.2) for ocular thermal gamble and 240 times below those limits for the photochemical chance. Although light intensity and free energy take non been measured for other smartphone models, information technology is suggested that they tin can be well beneath hazard limits.11

Although retinal images obtained with smartphone could be comparable to images taken by a fundus photographic camera,eight,10 recording a high-resolution smartphone retinal prototype requires an experienced examiner, a well-dilated pupil, clear ocular media, and a cooperative patient. Also, the field of view is usually express in smartphone fundus images and creating widefield montage images may exist fourth dimension consuming. Nevertheless, smartphone fundus photography is a unique simple and affordable technique that allows picture documentation of retinal changes in many clinical settings where retinal imaging was not previously possible.

Disclosures

No proprietary interest to declare.

Acknowledgments

This work is supported in part past an educational found FRS 445960.  We would like to give thanks Anh Tran, Juan Ortiz, and Ali Nazari for their help in preparing figure ii.

References

• Lord RK, et al. Novel uses of smartphones in ophthalmology. Ophthalmology. 2010;117(6):1274–1274. [PubMed] [Google Scholar]
• Chhablani J, Kaja S, Shah VA. Smartphones in ophthalmology. Indian J Ophthalmol. 2012;60(2):127–131. [PMC free article] [PubMed] [Google Scholar]
• Bolster NM, Giardini ME, Bastawrous A. The Diabetic Retinopathy Screening Workflow: Potential for Smartphone Imaging. J Diabetes Sci Technol. 2015;x(two):318–324. [PMC free article] [PubMed] [Google Scholar]
• Haddock LJ, Kim DY, Mukai S. Elementary, Cheap Technique for High-Quality Smartphone Fundus Photography in Human being and Animal Eyes. J Ophthalmol. 2013. [PMC complimentary article] [PubMed]
• Maamari RN, et al. A mobile phone-based retinal camera for portable wide field imaging. Br J Ophthalmol. 2014;98(4):438–441. [PubMed] [Google Scholar]
• Raju B, Raju NS. Regarding fundus imaging with a mobile telephone: a review of techniques. Indian J Ophthalmol. 2015;63(2):170–171. [PMC free article] [PubMed] [Google Scholar]
• Shanmugam MP, et al. Fundus imaging with a mobile phone: a review of techniques. Indian J Ophthalmol. 2014;62(9):960–962. [PMC free article] [PubMed] [Google Scholar]
• Adam MK, et al. Quality and Diagnostic Utility of Mydriatic Smartphone Photography: The Smartphone Ophthalmoscopy Reliability Trial. Ophthalmic Surg Lasers Imaging Retina. 2015;46(six):631–637. [PubMed] [Google Scholar]
• Snead MP, Rubinstein MP, Jacobs PM. The optics of fundus exam. Surv Ophthalmol. 1992;36(six):439–445. [PubMed] [Google Scholar]
• Russo A, et al. Comparing of smartphone ophthalmoscopy with slit-lamp biomicroscopy for grading diabetic retinopathy. Am J Ophthalmol. 2015;159(2):360–364. [PubMed] [Google Scholar]
• Kim DY, Delori F, Mukai S. Smartphone photography safety. Ophthalmology. 2012;119(ten):2200–2201. author answer 2201. [PubMed] [Google Scholar]

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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5609317/

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