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Diabetic retinopathy (DR) can be defined as a
serious ocular complication of diabetes mellitus
(DM). It can lead to impairment of vision and even
blindness when not detected and treated on time. It
is expected that one-third of diabetic individuals
1
will eventually develop DR. Clinical signs such as
micro-aneurysms, soft exudates, hemorrhages and
hard exudates, occur in DR because damaged tiny
2
blood vessels leak blood and fluid in the retina. DR
can be divided into two main classes: non-
proliferative DR which exhibits the above clinical
signs and proliferative DR, a more advanced form of
the disease involving the development of abnormal
Introduction blood vessels. Symptoms of DR include double
3
vision, blurred vision, difficulty perceiving
colours, dark spots in the field of view and floaters.
DR tends to occur in patients that have diabetes for a
longer period of time and can remain asymptomatic
until complicated signs such as vitreous
4,5,6
haemorrhage or retinal detachment emerge. Risk
factors for DR include prolonged duration of
dia betes, el evated g lycated h aemoglo bin,
7
hypertension and use of insulin therapy. Individuals
with diabetes will eventually be at risk of
developing DR with rapid increment occurring in
8,9
low and middle income countries. Thus there is
likelihood that DR could become a major health
10
challenge in various parts of the world. It is
necessary that diabetic individuals undergo dilated
retinal examination at least once a year as symptoms
11,12
of DR do not occur at its early stages. Various
ophthalmic procedures such as direct and indirect
ophthalmoscopy, slit lamp biomicroscopy, and
retinal fundus photography are used by clinical
1 2
Oseleonomhen Monica Odigie , Ghalib Ayoakin Akinlabi
Smartphone Imaging Devices for Screening of Diabetic Retinopathy: A Review
IBOM MEDICAL JOURNAL
Vol.15 No.1 January, 2022. Pages 1 - 7
ww w.ibomme dicaljo urnal.o rg
Abstract
Conclusion: Further research comparing various smartphone imaging devices for DR detection should
be carried out by health care professionals across various populations.
Results: Findings from this investigation revealed that some of these devices have the potential to detect
features of DR which could be beneficial to diabetic individuals living in developing nations.
Methodology: The Google search engine was used to investigate the details of different smartphone
imaging devices currently available for fundus examination. Studies that have evaluated these devices for
the detection of DR were also reported.
Keywords: Diabetic Retinopathy, Diabetes Mellitus, Smartphone fundoscopy, Retinal fundus images
Background: Innovative solutions are needed for retinal fundus examination in diabetic individuals as a
result of the projected rise in the global prevalence of Diabetic Retinopathy (DR) in the near future. Early
detection of DR will help to prevent avoidable blindness and lead to improvement of eyecare services for
diabetic individuals. Currently, smartphone fundoscopy is emerging as new form of retinal examination
because of the several advantages it offers, such as lower cost and portability, compared to the
conventional desktop cameras. This review seeks to describe the characteristics of commercially
available smartphone imaging devices.
Corresponding Author:Dr. Oseleonomhen Monica Odigie
Department of Optometry,
Faculty of Life Sciences,
University of Benin, Edo State, Nigeria.
E-mail: monica.odigie@uniben.edu, Phone: 08131089660
1
1,2Department of Optometry, Faculty of Life Sciences, University of Benin, Edo State, Nigeria.
19
Russo et al., 2015 created an inexpensive handy
optical accessory that can be magnetically attached
onto a smartphone. This device was derived from
the basis of direct ophthalmoscopy and can be used
to record videos and capture images of the retina. A
smartphone application assists in reducing the
intensity of the flash LED and alternating between
automatic and manual focus. The system is usually
Smartphone imaging devices
D-Eye
20D condensing lens
This method initially introduced by Lord et al.,
17
2010 involves holding a 20 D condensing lens
before a dilated pupil of a patient. The camera of the
smartphone will be placed along the pupillary axis
of the patient. The camera and the lens will both be
moved to find a good focus of the retina during
video recording. Thereafter, the recorded video is
played back and a screen shot of a good view of the
18
retina is taken.
experts to examine the retina for lesions associated
with DR. In addition, the mydriatic seven field
stereoscopic fundus colour imaging has been stated
12
as the ideal technique for the screening of DR.
Performing the above technique is complex, costly
and time consuming and as such is not suitable for
14,15
large-scale screening of DR. These challenges
have led to the development of smartphone imaging
systems as resourceful alternative for retinal
examination in the past decade. The processing
performance, connectivity and significant image
resolution of smartphones have allowed them to be
used in different professions including the medical
16
field.
The Google search engine was used to investigate
the specifications of various smartphone imaging
devices available for retinal examination. The
information was obtained from the different
companies’ websites and articles. Studies that have
validated some of smartphone imaging devices for
diabetic retinopathy screening were also retrieved
for review. Keywords used for searching include
fundus camera, retinal camera, retinal imaging,
fundus imaging, smartphone fundus photography,
diabetic retinopathy.
Methods
The Welch Allyn iExaminer is made up of PanOptic
ophthalmoscope, an application, an adapter, and an
iPhone. The PanOptic Ophthalmoscope provides a
25-degree field of view without dilating the pupils.
In order to acquire photographs of the retina, the
optical access of the PanOptic Ophthalmoscope is
aligned to the visual axis of the camera of the iPhone
with the use of an adapter. The Application then
enables the images to be stored in a patient file or
emailed and printed. iExaminer is compatible with
iPhone models: 4, 4S, 6, 6S and 6 Plus models.
placed at 1 cm from the eye of the patient and
thereafter the acquired images or videos of the retina
are saved either in the local storage or through a
secure server. D-eye is compatible with iPhone
models: 5, 5S, 6, 6S, 6 Plus, and 7 models.
iExaminer
oDocs nun
This is a next generation ophthalmoscope that has
compatibility with a range of smartphones both
Androids and iPhones. It is non-mydriatic as it
works for pupil sizes as small as 2mm. it also has 30-
degree field of view when the size of pupil is 4 mm
with a dynamic focus of +20D to -20D
Volk iN view fundus camera
Remidio Fundus on Phone Non Mydriatic (FOP
NM)
FOP NM is a smartphone-based system capable of
capturing good quality retina photographs. This
device uses high quality and precision optics to
illuminate and capture retinal images at a working
distance of 33cm. There is also a built-in application
(Remidio fundus software) used for viewing and
capturing retinal images in both mydriatic and non-
Volk iNview is an ophthalmic device that is made up
of an application and an indirect ophthalmoscopic
lens attachment. The application enables the device
to automatically capture and select the best images
of the retina. The device is mydriatic and capable of
obtaining a wide 50-degree field of view to see the
entire posterior pole in a single image. Thereafter
the retinal images are stored with the data of the
patient and can be easily transferred to a PC or Mac.
Volk iN view is compatible with iPhone 5S, 6, 6S,
and iPod Touch (Gen 6).
Oseleonomhen Monica Odigie et al
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Ibom Med. J. Vol.15 No1. January, 2022
Smartphone Imaging Devices for Screening of Diabetic Retinopathy...
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Ibom Med. J. Vol.15 No1. January, 2022
Oseleonomhen Monica Odigie et al Smartphone Imaging Devices for Screening of Diabetic Retinopathy...
Studies
Smartphone
Imaging
system
Reference
Standard
Kappa
Agreement
Severity of DR
Sensitivity
Specificity
Ryan et
al., 2015
20 diopter lens
and iphone 5
7-field
mydriatic
fundus
photography
Substantial
Moderate
Any DR
VTDR
50.0%
59.0%
94.0%
100%
Jamil et
al., 2018
20 diopter lens
and Samsung
galaxy N9000
Slit-lamp
biomicroscopy
Almost perfect
Almost perfect
Almost perfect
Almost perfect
Any DR
NPDR
PDR
Macular Edema
89.5%
81.8%
77.3%
82.6%
99.5%
95.9%
99.1%
99.6%
Bose and
Bose,
2018
20 diopter lens
and iphone 7
-
Almost perfect
NPDR
-
-
Russo et
al., 2015
D-Eye and
iphone 5
Slit-lamp
biomicroscopy
Almost perfect
Almost perfect
No DR
Mild NPDR
Moderate NPDR
Severe NPDR
PDR
Macular Edema
96.0%
75.0%
82.0%
55.0%
89%
81.0%
90.0%
93.0%
98.0%
99.0%
100%
98.0%
Sengupta
, et al.,
2017
Remidio
Fundus on
Phone (FOP)
Topcon camera
-
Any DR
93.1%;
94.3%
89.1%:
94.5%
Prathiba
et al.
2020
Remidio
Fundus on
Phone (FOP)
Zeiss FF450
fundus camera
Substantial
Almost perfect
Any DR
STDR
75.2%
82.9%
95.2%
98.9%
Types
Developer
Need for
dilation
Field of view
Image
recorded
Price
20 diopter
condensing
lens
Different
developers
Yes
46 degrees
Yes
Varies
D-eye
D- eye srl
No
5- 20 degrees
Yes
$400
iExaminer
Welch Allyn
No
25 degrees
Yes
$985
oDocs nun
oDocs Eye
Care
No
15 - 40
degrees
Yes
$1,120
Volk iNview
Volk Optical
Inc
Yes
50 degrees
Yes
$995
Remidio
Fundus on
Phone Non
Mydriatic
(FOP NM)
Remidio
Innovative
solutions
No
45 degrees
Yes
$8000
Table 1: Characteristics of different smart phone imaging systems
Table 2: Different smart phone imaging devices used for diabetic
retinopathy detection
Oseleonomhen Monica Odigie et al
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Ibom Med. J. Vol.15 No1. January, 2022
Smartphone Imaging Devices for Screening of Diabetic Retinopathy...
Figure 1. 1. 20D 31; 2.Volk iNview 32;
3.Remidio fundus on phone 33;
4.iExaminer 34; 5.oDocs nun 35; 6.d-eye 36.
1 2
3 4
5 6
20
Ryan et al. 2015 compared smartphone fundus
photographs with retinal images from Zeiss FF450
Plus table top fundus camera to access its ability to
detect DR. Three hundred diabetic patients were
examined at the Eye Department at Dr. Mohan's
Diabetes Specialties Centre located in India. A 20D
condensing lens and an iPhone 5 (Apple Inc.,
Cupertino, CA) with 3264 × 2488 pixels of the
sensor of the camera was used for acquiring retinal
images. Thereafter the images were graded by two
independent retinal specialists. The sensitivity and
specificity of smartphone fundus photography for
Studies on smartphone imaging systems for
diabetic retinopathy detection
mydriatic pupil. A minimum of 45-degree field of
view can give 10x magnification of the images of
the retina. The device has a dioptre correction of -
30D to +30D and is compatible with smartphone
camera of 8MP and above.
the detection of any DR were 50.0% and 94.0%
respectively. While the sensitivity and specificity of
smartphone fundus photography for the detection of
vision-threatening DR (VTDR; macular edema or
severe non-proliferative DR or worse) were 59.0%
and 100% respectively. There was moderate
agreement for any DR (k = 0.48) and substantial
21
agreement for VTDR (k = 0.71). Jamil et al. 2018
examined 125 diabetic individuals (250 eyes)
attending an ophthalmology department for the
presence of DR. Two different procedures, the 20D
and smartphone (Samsung galaxy N9000 with a
res o lution of 1920× 1 080) and slit lam p
biomicroscopy were assessed by two independent
ophthalmologists. The sensitivity and specificity for
detecting DR was 89.5% and 99.5% respectively.
The sensitivity and specificity for clinically
significant macular oedema (CSME) was 82.6%
and 99.6% respectively. There was almost perfect
agreement between the two methods for detecting
DR (k = 0.92) and CSME (k =0.87). Another study
22
by Bose and Bose 2018 evaluated retinal images
from iPhone 7 (Apple Inc., Cupertino, CA, USA)
smartphone and a 20D lens. Two investigators
(trained optometrists) examined 36 patients with
non- proliferative DR (NPDR). There was equal
agreement in the grading of NPDR in 33 of 36
patients. It was also observed that making use of
smartphones for fundus imaging becomes easier
when signs of NPDR such as microaneurysms,
haemorrhages and venous beading were more in
number. Smartphone Ophthalmoscopy using D-Eye
attached to iPhone 5 (Apple Inc, Cupertino,
California, USA) was compared with slit-lamp
biomicroscopy in detecting the different grades of
18
DR among 120 diabetic individuals. The range of
sensitivity of D-Eye for detecting the different
classes of DR was 55% to 96% while the range of
specificity was 90% to 100%. There was substantial
agreement for detecting any DR (k= 0.78). The
sensitivity and specificity of D-Eye for detecting
CSME were 81% and 98% while the kappa value
was 0.79 indicating almost perfect agreement.
23
Sengupta, et al. 2017 compared mydriatic retinal
photographs from Remidio Fundus on Phone (FOP)
with Topcon fundus camera. Also, a clinical
examination was conducted with a slit lamp
biomicroscope and indirect ophthalmoscope by a
retina specialist. Two independent retina specialists
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Ibom Med. J. Vol.15 No1. January, 2022
Oseleonomhen Monica Odigie et al Smartphone Imaging Devices for Screening of Diabetic Retinopathy...
The application of smartphone fundoscopy in
eyecare practice will lead to a more convenient form
of diagnosis of various eye conditions including
DR. Further researches comparing the effectiveness
of using the above devices for DR detection across
different populations should be conducted. This is in
order to determine appropriate and affordable
devices that can be easily acquired by clinicians
especially in developing nations where the high cost
of purchasing table top fundus camera remains a
challenge.
1. Congdon ING, Friedman DS, Lietman T.
Important causes of visual impairment in the
world today. JAMA 2003; 290(15):2057–2060.
Certain limitations have however been observed
with smartphone imaging devices. One of them is
that some of these devices are not compatible with
android phones. In addition, the adapters made for
iPhones are suitable for a particular iPhone model
making it difficult to upgrade to newer versions of
iPhones. Also, some of these devices have limited
field of view which is not ideal in accurately
detecting the clinical features of DR. In order to get
a retinal image from a smartphone device
comparable to images from a fundus camera, a
properly dilated eye, clear ocular media,
experienced examiner and cooperative individual
18,19,28
are needed.
2. Gandhi M, Dhanasekaran R. Diagnosis of
Diabetic Retinopathy Using Morphological
Process and SVM Classifier, IEEE International
conference on Communication and Signal
References
As improvements in technology will facilitate
improved capabilities of smartphone fundoscopy, it
is of upmost importance that privacy and data
security measures are implemented by these new
29,30
devices.
Acknowledgement: None
retinal images to clinical experts through the
internet for diagnosis (Tele-health Care).
Furthermore, Smartphone fundoscopy does not
require constant power source like the conventional
27
fundus camera.
Conclusion
Mass-screening and regular ocular examination
remains the only way for early detection and
management of DR as this will help to reduce loss of
25,26
vision by 50%. Conventional fundus cameras are
not readily available for fundus examinations in
developing nations in Africa because of the high
cost of such devices. In addition, patients have to
incur a significant amount of cost in order for retinal
photography to be performed on them. Another
factor is the bulky nature of these cameras can make
it challenging to be used as first choice equipment
for screening of DR.
Discussion
classified the retinal images from 135 individuals
(233 eyes) into different stages of DR. With retinal
photographs from the Remidio FOP, the first and
second grader reported a sensitivity of 93.1% and
94.3% respectively, in detecting any DR. With
retinal photographs from the Topcon fundus
camera, grader 1 and grader 2 reported a sensitivity
of 92.6% and 94.9% respectively. The sensitivity of
DR detection also increased from class 1 to 3 with
both graders and cameras. The performance of
Remidio FOP in the detection sight-threatening DR
(STDR; severe non-proliferative DR or worse with
macula oedema) in a tertiary eye care centre was
24
evaluated by Prathiba et al. 2020. Fundus
photography with Remidio FOP before mydriasis
and with Zeiss FF450 table top fundus camera after
mydriasis were obtained from diabetic individuals.
T he s e v e r i t y o f D R w as g r a de d b y
ophthalmologists. The sensitivity and specificity for
the detection of any DR were 75.2% and 95.2%
respectively with Remidio FOP. While the
sensitivity and specificity for the detection of STDR
were 82.9% and 98.9% respectively with Remidio
FOP. There was substantial agreement for detecting
any DR (k = 0.67) and almost perfect agreement for
detecting STDR (k =0.85) respectively.
Smartphone fundoscopy will likely become a
popular form of clinical examination in the eyecare
sector in the near future. Hence its capability in
detecting sight threatening conditions such as the
presence of DR will go a long way in reducing visual
impairment and blindness. This innovative form of
retinal examination offers several advantages such
as high level of screening of DR in regions with
limited access to eye care and easy transmission of
Oseleonomhen Monica Odigie et al Smartphone Imaging Devices for Screening of Diabetic Retinopathy...
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6
Ibom Med. J. Vol.15 No1. January, 2022
3. Ting DSW, Cheung GCM, Wong TY. Diabetic
retinopathy: Global prevalence, major risk
factors, screening practices and public health
challenges: A review. J Clin Exp Ophthalmol
2016; 44:260–277.
Processing, India 2013; 873-877.
12. Rechtman E, Harris A, Garzozi HJ, Ciulla TA.
Pharmacol o g i c therapies f or diabetic
retinopathy and diabetic macular edema," Clin
Ophthal (Auckland, NZ). 2007;1(4): 383-391.
8. Yau JW, Rogers SL, Kawasaki R, Lamoureux
EL, Kowalski JW, Bek T, et al. Global
prevalence and major risk factors of diabetic
retinopathy. Diab Care 2012; 35(3):556-564.
11. American Academy of Ophthalmology,
Preferred Practice Pattern Guidelines: Diabetic
Re t in o pa t hy, A mer i ca n A c ad e my of
Ophthalmology, 2008.
6. Gangwani RA, Lian JX, McGhee SM, Wong D,
Kw Li K. Diabetic retinopathy screening: global
and local perspective. Hong Kong Med
J.2016;22(5):486–495.
10. Gadekallu TR, Khare N, Bhattacharya S, Singh
S, Maddikunta PKR, Ra I, et al. Early Detection
of Diabetic Retinopathy Using PCA-Firefly
B a s e d D e e p L e a r n i n g
Model.Electronics.2020;9:274.
5. Ross EL, Hutton DW, Stein JD, Bressler NM,
Jampol NM, Glassman AR, et al. Cost-
effectiveness of aflibercept, bevacizumab, and
ranibizumab for diabetic macular edema
treatment: anal ysis from the Diabetic
Retinopathy Clinical Research Network
Comparative Effectiveness Trial. JAMA
Ophthalmol.2016;134(8):888–896.
4. Stitt AW, Curtis TM, Chen M, Medina RJ,
McKay GJ, Jenkins A, et al. The progress in
understanding and treatment of diabetic
retinopathy. Prog Retin Eye Res. 2016;
51:156–186.
9. Cho NH, Whiting D, Forouhi N, Guariguata L,
Hambleton I, Li R. et al. IDF diabetes atlas. 7th
ed. Brussels: International Diabetes Federation;
2015 ; (htt p : //acad e m ia.edu / 3 985316 1 /
IDF_DIABETES_ATLAS_Seventh_Edition,ac
cessed 18th July 2021).
7. Wat N, Wong RLM, Wong IYH. Associations
between diabetic retinopathy and systemic risk
factors. Hong Kong Med J.2016;22(6);589-599.
21. Jamil AZ, Bahoo MLA, Tahir MY, Shirazi FZ.
Smart Phone: A Smart Technology for Fundus
Photography in D i a b e t i c Ret i n o p a t h y
20. Ryan ME, Rajalakshmi R, Prathiba V, Anjana
RM, Ranjani H. Comparison Among Methods
of Retinopathy Assessment (CAMRA) study:
smartphone, nonmydriatic, and mydriatic
photography. Ophthalmology. 2015;122:2038-
2043.
13. Early Treatment Diabetic Retinopathy Study
Research Group. Grading diabetic retinopathy
f r o m s t e r e o s c o p i c c o l o r f u n d u s
photographs—an extension of the modified
Airlie House classification. ETDRS report
num ber 10. Ea rly Treatm ent Diabetic
Re t inop a thy Stu d y R e sea r ch G r oup .
Ophthalmol. 1991;98(5):786–706.
16. Akil,M. Elloumi Y. Detection of retinal
abnormalities using Smartphone-captured
fundus images: A survey. Real-Time Image
Processing and Deep Learning, Baltimore,
Mar y land U nite d Sta t e s; ( h ttp: / / hal-
enp c .archive s -ouvertes .fr/hal-0 2121855,
accessed 5 May 2021).
15. Felgueiras S., Costa, J., Gonçalves, J. and
Soares, F. Mobile-based Risk Assessment of
Diabetic Retinopathy using a Smartphone and
Adapted Ophtalmoscope. In Proceedings of the
11th International Joint Conference on
Biomedical Engineering Systems and
Technologies (BIOSTEC 2018);5:168-175.
14. Leasher JL, Bourne RR, Flaxman SR, Jonas JB,
Keeffe J, Naidoo K, et al. Vision Loss Expert
Group of the Global Burden of Disease Study.
Global estimates on the number of people blind
or visually impaired by diabetic retinopathy: a
meta-analysis from 1990 to 2010. Diab Care.
2016; 39(9):1643–1649.
17. Lord RK, Shah VA, San Filippo AN, Krishna R.
Novel uses of smartphones in ophthalmology.
Ophthalmol. 2010;117(6):1274.
18. Khanamiri H.N, Nakatsuka A, El-Annan J.
Smartphone Fundus Photography. J Vis Exp.
2017; 125: 55958.
19. Russo A, Morescalchi F, Costagliola C, Delcassi
L, Semeraro F. Comparison of smartphone
ophthalmoscopy with slit-lamp biomicroscopy
for grading diabetic retinopathy. Am J
Ophthalmol. 2015;159(2):360–364.
www.ibommedicaljournal.org
7
Ibom Med. J. Vol.15 No1. January, 2022
Oseleonomhen Monica Odigie et al Smartphone Imaging Devices for Screening of Diabetic Retinopathy...
32. Volk iNview f rom Volk Optical, Inc;
(https://www.ophthalmologyweb.com/5820-
Digi t a l- Fundus - C a mera/9 6 9 9 179-Volk-
iNview/,accessed 19 June 2021).
35. O d o c s n u n ;
(htt p s : // www.i d e a co nnectio n . c om/new-
inventions/new-odocs-nun-helps-prevent-
blindness-13643.html, accessed 18 June 2021).
34. A l l y n W . i E X A M I N E R ;
(https://www.welchallyn.com/en/microsites/ie
xaminer.html, accessed 19 June 2021).
30. Micheletti JM, Hendrick AM, Khan FN, Ziemer
DC, Pasquel FJ. Current and Next Generation
Portable Screening Devices for Diabetic
Retinopathy.J Diab Sci Tech. 2016; 10(2)
295–300.
31. B i o l e n s 2 0 d ;
(https://www.volk.com/products/bio-lens-20d,
accessed 19 June 2021).
33. R e m i d i o f u n d u s o n p h o n e ;
(https://www.remidio.com/fop.php, accessed
18 June 2021).
36. Teong J. Innovative retinal imaging device turns
smartphones into portable ophthalmoscopes;
(https://www.journalmtm.com/2015/innovative
-retinal-imaging-device-turns-smartphones-
into-portable-ophthalmoscopes-3/, accessed 19
June 2021).
29. Kumar S, Wang EH, Pokabla M.J, Noecker RJ.
Teleophthalmology assessment of diabetic
retinopathy fundus images: smartphone versus
sta ndard office co mputer worksta tion.
Telemedicine J E-health. 2012;18(2):158-162.
23. Sengupta S, Sindal MD, Baskaran P, Venkatesh
UPR . Sens i ti vity a nd S p e cific i t y of
Smartphone-Based Retinal Imaging for
Diabetic Retinopathy: A Comparative Study.
Ophthalmol Retina. 2019;3(2):146-153.
25. Klonoff DC, Schwartz DM. An economic
analysis of interventions for diabetes. Diabetes
Care. 2000;23(3):390-404.
27. Martin J, Peter N. How effective is smartphone-
based fundoscopy in identifying diabetic
r e t i n o p a t h y ?
(https://www.ndorms.ox.ac.uk/files/oxford-
university-global-surgery-group/, accessed 17
May 2021).
28. Adam MK, Brady CJ, Flowers AM, Juhn AT,
Hsu J, Garg SJ, et al. Quality and Diagnostic
Utility of Mydriatic Smartphone Photography:
The Smartphone Ophthalmoscopy Reliability
Trial. Ophthalmic Surg Lasers Imaging Retina.
2015;46(6):631–637.
24. Prathiba V, Rajalakshmi R, Arulmalar S, Usha
M, Subhashini R, Gilbert CE, et al. Accuracy of
the smartphone-based nonmydriatic retinal
camera in the detection of sight-threatening
diabetic retinopathy. Indian J Ophthalmol.
2020; (68)13: 42-46.
26. Fong DS, Aiello L, Gardner TW, King GL,
Blankenship G, Cavallerano JD, et al. Diabetic
Retinopathy. Diab Care 2003.26:226–229.
Screening. Pak J Ophthalmol 2018;34:(4) 225 -
230.
22. Bose S, Bose AK. Utility of smartphone-based
fundus camera device in a social outreach
setting. Egypt Ret J. 2018; 5 (1):21-23.
