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Shantanu Sinha, William States Lee, Ramesh Raskar; A Smartphone attachment for slit lamp-like imaging of the anterior segment of the eye. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1686.
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© 2017 Association for Research in Vision and Ophthalmology.
The slit lamp is the most commonly used ophthalmic device for examining the anterior segment of the eye, but is big, expensive, contains many moving parts and is designed with specialized ophthalmic clinics in mind. We present a smartphone attachment with minimal optics and no electronics, beyond the smartphone itself, to examine and image the anterior segment of the eye. This cost-effective solution would help extend the reach of anterior segment examination to resource constrained settings well beyond the scope of specialized clinics.
The proposed attachment utilizes the camera sensor and LED flash of the smartphone for imaging and illumination respectively. A system of mirrors and lenses splits the diverging beam emerging from the camera flash into two orthogonal collimated beams that illuminate the eye at 45 degrees with respect to the optical axis of the eye. Movable slits on both illumination pathways allow the user to select individual sheets of light bringing different cross-sections of the eye into view. These cross-sections are then imaged by the camera, placed along the optical axis of the eyeball.
The proposed compact smartphone attachment leverages on features commonly available in smartphones to provide slit-lamp like imaging without any additional electronics. The optics of the proposed prototype device provides a 45 degree angle between the illumination and imaging axes at all slit positions without the mechanical complexity of having two coaxial rotating arms like in conventional slit lamps. This results in a large viewing angle of the illuminated cross-section at all slit positions eliminating the need to change the direction the eye is viewed as the slit is moved.
We have proposed a compact smartphone attachment for slit lamp-like imaging of the anterior segment of the eye devoid of electronic components over what is commonly present in most smartphones available in the market today. Additionally through clever manipulation of illumination we are able to reduce hardware complexity found in conventional slit lamps while maintaining a constant 45 degree viewing angle of cross-sections of the eye at all slit positions. Low hardware requirements, beyond commercially available smartphones, would facilitate use of the device in resource constrained settings and in regions with poor access to ophthalmic clinics.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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