Miniaturized indirect ophthalmoscopy promises an affordable solution to foster smartphone wide-field fundus photography in telemedicine


Prognosis of eye diseases is vital for blindness and visual impairment prevention. Consequently, portable fundus imagers have become an essential for emerging telemedicine screening and point-of-care examination of eye diseases. Experience has shown that numerous eye diseases target the retina periphery. Unfortunately, the existing portable fundus cameras have limited field of view and frequently require pupillary dilation. Technological advances have led to the application of seven-field photography for diabetic retinopathy screening, based on traditional fundus cameras, so as to achieve the necessary view field coverage for mydriatic early treatment diabetic retinopathy study. However, the seven-field photography requires a skilled operator for pupillary dilation and image registration to produce montage images thereby making its deployment rural and underserved areas difficult.

Recently, a team of researchers led by Dr. Xincheng Yao from the Department of Bioengineering at University of Illinois at Chicago and Dr. Devrim Toslak from Department of Ophthalmology at Antalya Training and Research Hospital developed a miniaturized indirect ophthalmoscopy to enable wide-field smartphone fundus video camera. This work has been featured as a ‘New Instruments’ article in RETINA, the journal of retinal and vitreous diseases (Retina 38, 438-441, 2018).

Moreover, the team also constructed a benchtop prototype fundus camera to extend the miniaturized indirect ophthalmoscopy design for nonmydriatic wide-field photography. The nonmydriatic prototype device consists of a near-infrared light source for retinal guidance and a white light source for color retinal imaging. The authors observed that by incorporating digital image registration and glare elimination methods, a dual-image acquisition approach was applicable in achieving reflection artifact-free fundus photography. In addition, they noted that with NIR light guidance, they were able to capture at least three-color fundus images before pupil constriction could commence. This work has been published in Optics Letters.

In conclusion, the scientists at University of Illinois at Chicago presented a new miniaturized indirect ophthalmoscopy design to demonstrate a mydriatic wide-field smartphone fundus camera first, and also constructed a bench top prototype of nonmydriatic wide-field fundus camera in achieving a 67° external angle (101° eye angle) field of view in single-shot images. Altogether, the work demonstrated dual-image acquisition combined with digital data processing to achieve reflection artifact-free color fundus imaging which promises a portable next-generation, low-cost and wide-field fundus camera for affordable telemedicine and point-of-care assessment of eye diseases.

The authors anticipate that there is still a large room for further improvement of the FOV and image quality by professional optical design, promising a next-generation low-cost, non-mydriatic, wide-field fundus camera for affordable telemedicine and point-of-care assessment of eye diseases. This successful research work is now protected with a patent application (US 62/546,830).

Miniaturized indirect ophthalmoscopy promises an affordable solution to foster smartphone wide-field fundus photography in telemedicine - Advances in Engineering

About the author

Xincheng Yao, PhD is a Richard & Loan Hill Professor of Bioengineering and Ophthalmology, University of Illinois at Chicago (UIC). Dr. Yao received his PhD in Optics from the Institute of Physics, Chinese Academy of Sciences in 2001. This was followed by his postdoctoral research in biomedical optics at Los Alamos National Laboratory (LANL) from 2001 to 2004. He held a LANL Technical Staff appointment from 2004 to 2006, served at CFD Research Corporation as a Senior Research Scientist from 2006 to 2007, and worked at UAB as an Assistant Professor and Associate Professor from 2007 to 2014. His research interest is biomedical optics instrumentation and retinal imaging.

About the author

Devrim, Toslak, MD is an ophthalmologist in Antalya Training and Research Hospital, Antalya, Turkey. Dr. Toslak received his MD degree at Cerrahpaşa Faculty of Medicine, Istanbul University in 2000. He completed his ophthalmology residency at Istanbul Haydarpasa Numune Training and Research Hospital in 2004. He is currently studying at Department of Bioengineering, University of Illinois at Chicago, Illinois, United States.

His clinical and scientific interests are focused on ophthalmology, vision science and bioengineering.. He studies to construct affordable ophthalmic imaging devices for under-served areas and under-developed counties.


1) Devrim Toslak, Ali Ayata, Changgeng Liu, Muhammet Kazim Erol, Xincheng Yao. Wide-field smartphone fundus video camera based on miniaturized indirect ophthalmoscopy. Retina (Philadelphia, Pa.), 38(2), 438-441(2018).

Go To Retina (Philadelphia, Pa.)

2) Devrim Toslak, Changgeng Liu, Minhaj Nur Alam, Xincheng Yao. Near-infrared light-guided miniaturized indirect ophthalmoscopy for nonmydriatic wide-field fundus photography.Optics Letters, 43(11), 2551-2554 (2018)

Go To Optics Letters

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