Feasibility and clinical utility of handheld fundus cameras for retinal imaging

Abstract

Background/objectives: Handheld fundus cameras are portable and cheaper alternatives to table-top counterparts. To date there have been no studies comparing feasibility and clinical utility of handheld fundus cameras to table-top devices. We compare the feasibility and clinical utility of four handheld fundus cameras/retinal imaging devices (Remidio NMFOP, Volk Pictor Plus, Volk iNview, oDocs visoScope) to a table-top camera (Zeiss Visucam^NM/FA).

Subjects/methods: Healthy participants (n = 10, mean age ± SD = 21.0 ± 0.9 years) underwent fundus photography with five devices to assess success/failure rates of image acquisition. Participants with optic disc abnormalities (n = 8, mean age ± SD = 26.8 ± 15.9) and macular abnormalities (n = 10, mean age ± SD = 71.6 ± 15.4) underwent imaging with the top three scoring fundus cameras. Images were randomised and subsequently validated by ophthalmologists masked to the diagnoses and devices used.

Results: Image acquisition success rates (100%) were achieved in non-mydriatic and mydriatic settings for Zeiss, Remidio and Pictor, compared with lower success rates for iNview and oDocs. Image quality and gradeability were significantly higher for Zeiss, Remidio and Pictor (p < 0.0001) compared to iNview and oDocs. For cup:disc ratio estimates, similar levels of bias were seen for Zeiss (-0.09 ± SD:0.15), Remidio (-0.07 ± SD:0.14) and Pictor (-0.05 ± SD:0.16). Diagnostic sensitivities were highest for Zeiss (84.9%; 95% CI, 78.2-91.5%) followed by Pictor (78.1%; 95% CI, 66.6-89.5%) and Remidio (77.5%; 95% CI, 65.9-89.0%).

Conclusions: Remidio and Pictor achieve comparable results to the Zeiss table-top camera. Both devices achieved similar scores in feasibility, image quality, image gradeability and diagnostic sensitivity. This suggests that these devices potentially offer a more cost-effective alternative in certain clinical scenarios.

Fig. 1. Overview of table-mounted and handheld fundus cameras/retinal imaging devices and fundus images.

The devices used in this study (top panel) and corresponding images acquired (bottom panel) are shown.

Fig. 2. Imaging acquisition success.

Bar charts demonstrating the percentage success rates for image acquisition from the devices utilised in the study in (A) non-mydriatic and (B) mydriatic settings.

Fig. 3. Clinician grading for imaging quality and gradeability.

A Bar chart demonstrating the median Likert score for image quality for each imaging modality with error bars indicating the upper interquartile range for each corresponding median. Bar charts demonstrating the percentage gradeability of the (B) optic disc and (C) vascular morphology for each imaging modality.

Fig. 4. Comparsion of patient experience of each imaging modality.

Bar charts demonstrating the median (A) overall comfort and (D) proximity scores of each imaging modality with error bars representing the upper interquartile range of the corresponding median. Bar chart displaying the mean (B) brightness and (C) length of examination scores of each imaging modality as given by participants with error bars corresponding to the upper standard deviation of each corresponding mean.

Fig. 5. Comparison of clinician estimates of cup:disc ratio against reference standards.

Figures demonstrating the results of the Bland–Altman test for agreement and bias performed for optic cup:disc ratios for (A) Zeiss, (B) Remidio NMFOP and (C) Pictor.