standard in a masked, randomized trial of 111 consecutive individuals (222 eyes) with diabetes [7]. Subjects had both seven field stereo ETDRS photographs and DigiScope® images taken. Agreement on “no diabetic retinopathy” versus presence of “any diabetic retinopathy” was nearly perfect (Kappa 0.97 right eye, 0.94 left eye). This was reflected in very high sensitivities (0.99 right eye, 1.00 left eye) and specificities (1.00 right eye, 0.92 left eye). Agreement based on “microaneurysm or less retinopathy” versus “retinal hemorrhage or worse retinopathy,” the level of retinopathy at which referral is recommended with our system, was very good to excellent (0.78 right eye, 0.88 left eye). The sensitivities (0.95 right eye, 0.98 left eye) and specificities (0.81 right eye, 0.87 left eye) were also quite high based on this classification. There was also excellent agreement between the two imaging modalities with respect to which images were gradable indicating that imaging problems were not specific to the DigiScope®.

11.4Imaging Procedure

Initial training of the office staff to operate the DigiScope® for patient data entry and to acquire images requires approximately 1 h. Patients with diabetes who are visiting their primary care physician for a regularly scheduled visit and have not undergone an eye examination in the preceding 12 months are given the option of an assessment with the DigiScope® imaging system. Patients are informed that this procedure does not replace a comprehensive eye examination. After the procedure is explained to them, the patient’s pupils are dilated with 0.5% tropicamide. Typically, to minimize disruptions to normal patient flow, pupil dilation occurs while the patient is undergoing their scheduled physician encounter, and fundus imaging is performed prior to leaving the office. A member of the office staff enters patient data into the DigiScope® and uses the instrument to determine an approximate spherical equivalent visual acuity for each eye. The instrument is

then used to acquire fundus images. After pupil dilation, patients are asked to view a target light inside the unit (Fig. 11.2). The operator views an image of the subject’s pupil on the touch screen. By touching the screen in the center of the pupil image, the camera head moves automatically to center the pupil. A series of pupil images is then acquired over a range of distances from the cornea allowing the operator to select the image in best focus on the screen. The optical head is then set to the corresponding location, and a series of fundus images is acquired with illumination from a red-free light. Ten internal fixation lights are used to orient the eye to acquire ten fundus images covering the posterior pole. The procedure is repeated for the fellow eye. The entire procedure for both eyes, including data entry, requires approximately 10 min.

The current protocol for DigiScope® imaging utilizes pharmacological pupil dilation in order to increase the proportion of gradable images. A significantly higher rate of unreadable photographs through undilated versus dilated pupils has been reported [8, 9]. Patients with diabetes often have smaller pupils and a greater incidence of cataracts which may limit image quality if performed through an undilated pupil. Pupillary dilation is associated with a very small risk of angle-closure glaucoma. The risk of inducing angle-closure glaucoma with dilation using 0.5% tropicamide, as we recommend for the DigiScope® imaging procedure, is minimal with no reported cases in a large meta-analysis of published data [10]. In our series of over 100,000 imaging encounters, a single possible caseofangle-closureglaucomareportedlyoccurred, was immediately recognized, and was treated without adverse sequelae. It is imperative that the primary care physician and staff are familiar with the symptoms of angle-closure glaucoma and know to refer patients with such symptoms for immediate treatment. Part of the training prior to implementation of our technology in a physician’s office includes verbal instruction and written educational material on recognition of the signs and symptoms of angle-closure glaucoma.

11.4.1 Reading Center Procedure

The DigiScope® procedure results in the storage of digital data containing the images, encrypted patient information, and instrumental parameters. At a time least disruptive to the clinical practice (e.g., overnight or after clinic hours), the data are automatically electronically uploaded from the DigiScope® to a remote server by existing communication lines in an encrypted HIPAAcompliant manner. The Wilmer-EyeTel Reading Center is staffed by trained and certified readers, an optometrist, and a retina specialist, who provides overall oversight. For each subject, the data are presented on three monitors in the reading center. An algorithm automatically identifies the best of each of the images acquired at each fixation location. The three monitors allow all images of each eye to be viewed on a separate monitor with the third monitor to view each individual image at full resolution (Fig. 11.3). The reader reviews the images for retinal abnormalities, selects the nature of the retinopathy or other

abnormality from a pull-down menu on the screen, and uses a cursor to mark the lesion on the screen. Strict criteria for unreadable images have been defined. A retina specialist reviews all ambiguous cases, urgent referrals, data from all patients insured by Medicare, and data from random patient encounters for quality control. A report is generated in less than 48 h, and the results are transferred back to the primary care physician with a recommendation regarding the need for referral to an ophthalmologist for further evaluation and possible treatment or reassessment in 6 or 12 months. The report also includes photographs of any abnormalities identified on the images. For urgent referrals, the primary care physician is also alerted to the findings by a phone call.

Readers for the reading center undergo an extensive 6-month training program and testing before they can be certified to evaluate images independently. A study of 813 consecutive imaging encounters was performed to evaluate the ability of trained and certified readers who are