Abstract
Purpose::
The process of screening with image acquisition, tonometry, and image interpretation can be time consuming and therefore limits the number of subjects screened. By reducing the procedure time, we can improve screening efficiency and increase numbers served. We evaluated a novel set-up to screen subjects while in a standing position using a high-resolution, digital, non-mydriatic retinal camera coupled with a series of digital software filters to enhance image studies.
Methods::
Our novel VTD screening set-up consists of: a mechanical table mount that elevates to 6’5’’ height (Anthro, Tualatin, OR), a Canon CR-DGi 8.2 megapixel non-mydriatic digital camera (Tokyo, Japan), a Canon TXF non-contact tonometer (Tokyo, Japan), a SIFIMAV for visual acuity (Palermo, Italy), an ambulatory blood pressure monitor (A&D Co., Tokyo, Japan), and a Laptop computer (Fujitsu, Tokyo, Japan). Captured images were processed through software (Eye-Q capture, Irvine, CA) to expedite archiving and clinical assessment of images. Software-driven digital imaging filters (Eye-Q Pro, Irvine, CA) were used to separate monochromatic channels of posterior pole layers. A blue (490 nm), green (550 nm) and red (610nm) digital filter, and a 3-dimensional view of the posterior pole is created from a single image utilizing this digital process (EyeScape, Synemed, California, USA).
Results::
Over 328 color images were acquired during 11 screening sessions. The monochromatic channels were useful for VTD detection: blue digital filter illustrated NFL drop out and macular pucker, green digital filter best revealed diabetic retinopathy and retinal hemorrhages, red digital filter displayed AMD associated macular changes (drusen and pigment epithelial defects) and choroidal nevi. We found that the 3-dimensional, embossed view of the posterior pole best enhanced topographic changes (macular holes/traction, retinal edema, and NFL drop out). Fifteen images with NFL defects or glaucomatous neuropathy, six images with AMD and twenty with diabetic retinopathy were observed. Imaging and data acquisition time per subject were reduced by up to 50% (3 minutes) when subjects (up to height 6’5") were screened while in a standing position versus 6 minutes in the sitting position by conventional method.
Conclusions::
VTD capture rate can be enhanced by screening subjects that are standing at a modified set-up with a non-mydriatic retinal camera, non-contact tonometer, and software-driven digital imaging filters. Using this protocol, screening time can be reduced by almost 50%. The digital image processing can further enhance appearance of retinal pathology and may improve VTD detection.
Keywords: imaging/image analysis: clinical • image processing • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)