The field of teleophthalmology has been expanding in recent years due to the development and advancement of mobile fundus cameras. Many of these devices involve taking a video of the retina using a smartphone coupled with an attachable lens system. Despite recent advances, the videos that are obtained with these devices can sometimes be difficult to use for clinical purposes. This is because the videos often have a small field of view and can include blurry frames and blinks. In order to improve the ease at which these videos can be obtained and interpreted, a stabilization system and Android application for processing these videos was created. This Android application is intended to exclude unusable video frames, and stitch together the remaining frames into a single image. The effectiveness of this application is tested using videos obtained with the D-EYE device. These images are then compared to clinical images, and images obtained from the DEYE without the image stitching application. In this study, the image quality of the stitched images was found to be worse than that obtained from a clinical device.
Retinal examination using direct ophthalmoscope is preferred over other techniques for screening purposes because of its portability and high magnification, despite its power sustainability and cost issues. With increasing number of low-cost sustainable devices available in the market, it is important to assess the efficacy of the devices. We compared three devices - Arclight ophthalmoscope, a D-Eye attached to iPhone 6, and conventional ophthalmoscope Heine K180 - in terms of ease of examination, usage, field of view, color rendition, patient comfort, length of examination, and closeness to the eye. Two trained optometrists examined 26 undilated eyes and graded the ease of retinal examination, ease of use and assessed vertical cup:disc ratio (VCDR). Patients reported their comfort level in terms of glare produced by the light source, length of examination and closeness to the eye. The examiners had a good agreement for all assessments. Of 26 eyes, VCDR assessment was not possible in 10/26 (38.4%) of the examinations, in (3/26, 11.5%) examinations with Arclight, in 0/26 examinations with D-Eye. Ease of use score was higher for Arclight and D-Eye than Heine. D-Eye had a relatively larger field of view than other 2 devices. Heine ranked first in color rendition. The luminance level of the high-beam setting of Arclight was more than twice that of Heine and D-Eye. Despite that, the patients reported experiencing uncomfortable glare in Heine (14/26, 53.8%), significant glare with Arclight (16/26, 61.5%) and some/no glare with D-Eye. The examination time was shorter when using D-Eye. Overall, D-Eye scored better in most of the evaluation items followed by Arclight.
Fundus cameras are the current clinical standard for capturing retinal images, which are used to diagnose a variety of sight-threatening conditions. Traditional fundus cameras are not easily transported, making them unsuitable for field use. In addition, traditional fundus cameras are expensive. Due to this, a variety of technologies have been developed such as the D-EYE Digital Ophthalmoscope (D-EYE Srl, Padova, Italy) which is compatible with various cellphone cameras. This paper reports on the comparison of the image quality of the Nidek RS-330 OCT Retina Scan Duo (Nidek, Tokyo, Japan) and the D-EYE paired with an iPhone 6 (Apple, Cupertino, USA). Twenty-one participants were enrolled in the study of whom 14 underwent nonmydriatic and mydriatic imaging with the D-EYE and the Nidek. Seven participants underwent nonmydriatic imaging with the D-EYE and the Nidek. The images were co-registered and cropped so that the region of interest was equal in both the D-EYE and Nidek images, as the D-EYE had a smaller field of view. Using the Nidek image as the reference, objective full-reference image quality analysis was performed. Metrics such as structural similarity index and peak signal noise ratio were obtained. It was found that the image quality of the D-EYE is limited by the attached iPhone camera, and is lower when compared to the Nidek. Quantification of the differences between the D-EYE and Nidek allows for targeted development of smartphone camera attachments that can help to bridge the current gap in image quality.
The direct ophthalmoscope, a handheld device gives a highly magnified image of the retina. However, the sustainability of power source and cost are a limitation considering the usage demand. We compared a low-cost solar-powered Arclight ophthalmoscope with a standard ophthalmoscope Heine K180 in terms of ease of examination, usage, field of view, color rendition and patient comfort. Two clinically trained optometrists examined 28 patients and graded the ease of retinal examination, ease of use and assessed cup-disc ratio, which is an important diagnostic parameter for glaucoma, patient comfort and length of examination (scale 1-4). The examiners had good agreement for all assessments. Of a total of 78 examinations, only 8(10.3%) did not result in cup-disc ratio measurement in the undilated pupil condition using both devices. Ease of use was scored higher for Arclight than Heine but this was not statistically significant. In conditions like large discs, the Arclight resulted in easier examinations due to its larger field of view. Color rendition was better with the Heine device. In undilated pupils, the patients often reported that there was significant glare with Heine, however, post-dilation, they reported more glare with Arclight compared to Heine (73% versus 55%). The performance of Arclight was comparable to that of Heine and can be considered a low-cost alternative to the standard direct ophthalmoscope especially in large-scale patient examinations in developing countries where cost might be a factor.
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