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 Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 4  |  Issue : 2  |  Page : 82-85

Smartphone fundoscopy for retinopathy of prematurity


Department of Ophthalmology, National University Hospital, College of Medicine, National University, Taipei, Taiwan

Date of Web Publication7-Apr-2017

Correspondence Address:
Po-Ting Yeh
Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Number 7, Chung-Shan South Road, Taipei
Taiwan
Tzyy-Chang Ho
Department of Ophthalmology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Number 7, Chung-Shan South Road, Taipei
Taiwan
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Source of Support: None, Conflict of Interest: None


DOI: 10.1016/j.tjo.2014.04.001

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  Abstract 


Purpose: The utility of digital fundus images in retinopathy of prematurity (ROP) screening has been established. A smartphone can be a device available to most ophthalmologists to capture digital fundus photographs. In this study, fundus images were captured with original camera settings for ROP documentation.
Methods: The examination was performed under topical anesthesia. An assistant held a glass stick against the eye movement if infants moved their eyes too frequently. A hand-held smartphone and a 30D lens were used to record the fundus in video mode. A continuous flash was turned on to provide almost constant coaxial illumination. Fundus photographs were captured from the video film.
Results: Fundus photographs can be captured successfully with a smartphone and a 30D lens under original camera settings.
Conclusion: Fundus photographs of acceptable diagnostic quality can be obtained in ROP patients conveniently and inexpensively using a portable hand-held smartphone. It might be a useful tool in documentation, education, consultation, and telemedicine in ROP.

Keywords: fundoscopy, retinopathy of premature, smartphone, telemedicine


How to cite this article:
Lin SJ, Yang CM, Yeh PT, Ho TC. Smartphone fundoscopy for retinopathy of prematurity. Taiwan J Ophthalmol 2014;4:82-5

How to cite this URL:
Lin SJ, Yang CM, Yeh PT, Ho TC. Smartphone fundoscopy for retinopathy of prematurity. Taiwan J Ophthalmol [serial online] 2014 [cited 2019 May 25];4:82-5. Available from: http://www.e-tjo.org/text.asp?2014/4/2/82/204031




  1. Introduction Top


The number of smartphone owners has increased in recent years. The availability of smartphones and advances in technology for capturing images has resulted in the wide use of smartphones as clinical imaging devices in ophthalmology.[1] This application, which has been facilitated by the ease of use and portability of the device and the already extensive mobile-phone networks, presents a unique opportunity for telemedicine. Rapidly advancing technology has brought about the possibility of taking fundus photographs in the palm of our hands.[2] Smartphones can be used to take external photographs of eyes, slit-lamp pictures of the anterior segment, and fundus photographs through a slit lamp or a lens for numerous retinal diseases.[1]

Retinopathy of prematurity (ROP) is the leading cause of blindness in children worldwide. According to the Early Treatment for Retinopathy of Prematurity study, treatment is recommended for type I prethreshold ROP. Early treatment of high-risk prethreshold ROP can reduce unfavorable outcomes significantly.[3] For the early detection, an accurate fundus image is acquired and interpreted by an experienced ophthalmologist. Fundus was traditionally evaluated onsite; nowadays, digital fundus photography is used in ROP screening to facilitate consultation in difficult cases and contribute to medical legal affairs. However, it is not easy to take a fundus photograph of a newborn without professional equipment, especially for ROP screening, such as the RetCam system,[4] which is costly and unaffordable in most of the local medical healthcare environments. Smartphone fundoscopy can inexpensively share the same advantages of telemedicine, either to document the fundus status or to consult experienced senior ophthalmologists. Besides, the light source of smartphones is safe for human eyes. Retinal irradiance from a smartphone (iPhone 4) is less than that from an indirect ophthalmoscope.[5]

Various applications and devices are available for smartphone cameras that can increase the image quality of fundoscopy to capture diagnostic images. Previous studies used a paid application “Filmic Pro” to take fundus photographs to get higher-quality images.[6] Some mobile phone cameras were designed to capture wide field images.[7] Theoretically, a modern smartphone camera is already equipped with a high-quality optical system and a coaxial light source, which can be applied to capture high-resolution retinal images. In this study, we used smartphones to take good fundus photographs of ROP patients under original camera settings, without any paid applications.


  2. Methods Top


2.1. Patients

From December 2013 to January 2014, fundus images of six infants with ROP were recorded by the methods described below. All infants were awake without general anesthesia when they were under fundus examination and being photographed. Pupils of the patients were dilated. Only a topical anesthesia was administered for applying an eyelid speculum and performing scleral indentation. One nurse assisted in holding the infant’s head stable.

2.2. Technique

Images were captured with a smartphone, either iPhone 4S (Apple Inc., Cupertino, CA, USA) or HTC One (HTC Corporation, New Taipei City, Taiwan), and a 30D lens (Volk Optical Inc., Mentor, OH, USA). The ophthalmologist held a 30D lens and a smartphone, which was treated as a video camera and a light source, to perform indirect fundoscopy [Figure 1]. The smartphone camera was switched to video mode, and the continuous flash was turned on to have coaxial light constantly illuminated. Different viewing and illumination axes can minimize reflections from the lens and the cornea. Pupils should be fully dilated to reduce light reflection. If the infant’s eyes moved too frequently, an assistant was needed to hold a glass stick, which was also used for scleral indentation, against the eye movement.
Figure 1: Smartphone with 30D lens used to record the fundus in video mode.

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The 30D lens should be clean, without any dust particles on it. Otherwise, it may mislead the autofocus of the phone camera. The cornea should be kept moist with normal saline drops. However, too much liquid pooling between the lids and the corneal surface will cause an unexpected glare and reflection of light. A cotton swab may be used to soak excess liquid. Through a clear medium, the iPhone camera can automatically focus on the retina. If any manual focusing or zooming is desired, it can be performed by the same hand holding the iPhone.

Tapping once on the screen can make the smartphone automatically focus and adjust exposure to the desired region. The iPhone user can lock the focus and exposure by tapping and holding on the desired region until “AE/EF Lock” appears at the bottom of the screen. This was useful especially when the cornea was hazy and obscured the retinal vessels, disturbing the autofocus function. If the light reflection is too severe, the light intensity can be reduced by covering the flash with three layers of Micropore tape (3M, St. Paul, MN, USA).[6] Once recording was completed, images were captured from the video sequence by taking a screenshot (by pressing and holding Home and Sleep/Wake button simultaneously) or transferring the desired video to the computer to print the screen.


  3. Results Top


Fundus photographs could be recorded successfully in all six infants using a smartphone and a 30D lens under the original camera settings, with a constant flash in video mode. Representative pictures taken from four infants are described and shown here. [Figure 2] shows a normal posterior retina captured using an iPhone 4s. The direction of the light and lens could be adjusted to record different parts of the fundus. One assistant was needed to perform scleral indentation for peripheral retina examination and photography. By sclera indentation, the interface between normal and avascular retina, which had a “popcorn-like” appearance, and ora serrata could be clearly captured using an iPhone 4s [Figure 3]A and [Figure 3]B. Three layers of Micropore tape were effective in eliminating the unexpected glare and reflection [Figure 3]A and [Figure 3]B,[Figure 4]). [Figure 5] shows comparisons between fundus photographs taken with and without covering the flash with tape.
Figure 2: Normal posterior retina captured by iPhone 4s.

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Figure 3: (A) “Popcorn” appearance anterior to the indentation and (B) “popcorn” appearance anterior to the indentation and ora serrata posterior to the indentation captured by iPhone 4S, with three layers of tape covering the flashlight.

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Figure 4: Plus sign captured by iPhone 4S, with three layers of tape covering the flashlight.

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Figure 5: Fundus photographs taken (A) with and (B) without tape covering the flash.

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Fundus photographs can also be recorded by HTC One and a 30D lens under the original camera settings. Stage 3 ROP in an infant that received laser treatment is shown in [Figure 6]. Regressed stage 3 ROP with vessels across the site of fibrovascular proliferation and laser spot over the avascular zone were captured by HTC One [Figure 6].
Figure 6: After laser treatment, regressed stage 3 ROP with vessels across the site of fibrovascular proliferation captured by HTC One.

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  4. Discussion Top


The use of a smartphone to capture fundus images has several advantages. First, a smartphone has an almost coaxial, constant, and powerful light source that can directly illuminate the fundus, making it easy to observe and photograph. Second, the smartphone camera can adjust exposure time automatically and focus on the retina. Third, fundoscopy with a smartphone is an inexpensive, easy, and portable way to record the retinal condition of patients with ROP. Although the quality of the picture is not equivalent to those taken by professional equipment, the cost–performance value is higher. In addition, chances of availability of a smartphone in local hospitals or relatively poor medical healthcare environments are high. The technique is helpful in patient consultation by experienced ophthalmologists, and the ease of sharing images makes smartphone fundoscopy a useful technique for ROP screening.

Using our procedures, zone III of the retina could be seen clearly by scleral indentation and eyeball rotation. A smartphone can capture the retinal image more peripheral than the professional wide-field digital fundus imaging system. [Figure 3]B shows ora serrata of the retina and the pars plana, which are more peripheral than zone III area. As long as the retinal zone can be viewed on the screen, detailed vascular changes can be observed by appropriate focusing. Besides, on average, full examination of one eye can be completed in 1 minute, without general anesthesia, by an experienced examiner. Actually, the time required to take fundus images using a smartphone is only slightly longer than that required by traditional indirect ophthalmoscopy.

Smartphone fundoscopy has certain limitations. First, the light emitted by a flash is much more divergent than the light source of a binocular indirect ophthalmoscope. We had tried to make a small cylinder device with a black straw and a lens sticking in front of the flash to converge the light. Although the light reflection was reduced, intensity was increased and caused some regions overexposed on the image. In some of the smartphones flash intensity of the in-built camera cannot be controlled, which is of concern. Covering the flash with tape can be an alternative way to reduce light intensity.[6] Although this technique reduces the light intensity, it can improve the quality of imaging [Figure 5]A and [Figure 5]B.

Fundus photographs of acceptable diagnostic quality can be obtained by a portable hand-held smartphone. Digital photographs can be sent immediately and conveniently through emails or applications for acquisition of fundus images of ROP patients, for documentation and consultation. The technique is relatively easy to master and inexpensive, and above all, it can take advantage of the expanding cellular phone communications for telemedicine.

Conflicts of interest: All authors declare no conflicts of interest.



 
  References Top

1.
Lord RK, Shah VA, San Filippo AN, Krishna R. Novel uses of smartphones in ophthalmology. Ophthalmology. 2010;117:1274.  Back to cited text no. 1
    
2.
Bastawrous A. Smartphone fundoscopy. Ophthalmology. 2012;119:432–433.  Back to cited text no. 2
    
3.
Good WV, Early Treatment for Retinopathy of Prematurity Cooperative Group. Final results of the Early Treatment for Retinopathy of Prematurity (ETROP) randomized trial. Trans Am Ophthalmol Soc. 2004;102:233–248. discussion 248–250.  Back to cited text no. 3
    
4.
Ells AL, Holmes JM, Astle WF, Williams G, Leske DA, Fielden M, et al. Telemedicine approach to screening for severe retinopathy of prematurity: a pilot study. Ophthalmology. 2003;110:2113–2117.  Back to cited text no. 4
    
5.
Kim DY, Delori F, Mukai S. Smartphone photography safety. Ophthalmology. 2012;119:2200–2201.  Back to cited text no. 5
    
6.
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.  Back to cited text no. 6
    
7.
Maamari RN, Keenan JD, Fletcher DA, Margolis TP. A mobile phone-based retinal camera for portable wide field imaging. Br J Ophthalmol. 2014;98:438–441.  Back to cited text no. 7
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


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Abstract
1. Introduction
2. Methods
3. Results
4. Discussion
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