Ординатура / Офтальмология / Английские материалы / Diabetes and Ocular Disease Past, Present, and Future Therapies 2nd edition_Scott, Flynn, Smiddy_2009

374 Diabetes and Ocular Disease

OVERVIEW

Telemedicine is the delivery of health services and information through integrated networks of computer and telecommunications technology. It offers the possibility of increased access to health care, particularly specialty care, when and where it is most needed. Telemedicine may also reduce escalating medical costs by substituting effective, but less expensive, alternatives to traditional health care delivery systems [7].

Diabetic retinopathy is well suited for assessment by telemedicine. Slide film photography has been used in large, multicenter diabetic retinopathy clinical trials for remote evaluation since 1970. The progression of disease between treatment and observation groups has been compared successfully through photography [8]. Digital photography significantly advances health care delivery options. Digital images can be transmitted electronically from remote locations directly to specialists for evaluation. Digital photographs can also be reviewed immediately onsite because they do not require the processing time normally associated with film photography.

The integration of computers and telecommunications into the care of diabetic retinopathy is an opportunity to make dramatic inroads into this serious public health problem. Telemedicine can extend health care resources to underserved areas, increasing the number of diabetic patients assessed for retinopathy. Telemedicine can also improve screening rates by making evaluation more convenient for patients, even in areas where specialty care is available. Patient visits to specialists could be streamlined by telemedicine directing only those with retinopathy or in need of treatment to traditional evaluation.

DIABETIC RETINOPATHY TELEMEDICINE PROGRAMS

Worldwide use of telemedicine to identify diabetic retinopathy is growing in response to the increasing prevalence of diabetes and the decreasing cost of teletechnology. In Australia, high rates of diabetes in indigenous populations have led to the development of innovative telemedicine projects. Various systems are in place to screen for diabetic retinopathy in people of aboriginal ancestry living in rural communities. Programs use nonmydriatic retinal cameras linked to digital backs. People from the community are often trained and credentialed as photographers, providing the additional benefit of local employment and education [9]. Once identified, patients with diabetic retinopathy are referred to an ophthalmologist for assessment [10–12]. At the Lions Eye Institute in Perth, researchers are working on the development of a portable handheld camera that could be used to screen for diabetic retinopathy and other eye diseases [13].

The creation of a teleophthalmology reimbursement code in some Canadian provinces has led to the development of a web-based, stereoscopic telemedicine system (Fig. 19.1). Funding for the Web server’s development and maintenance is generated by telemedicine patient evaluations. Costs for remote mobile camera units including personnel are covered by the federal and provincial governments.

Figure 19.1. Photograph showing the use of LCD shutter goggles for stereo viewing of retinal images at the University of Alberta Tele-Ophthalmology Reading Center. (Source: Courtesy of Richard Siemens with permission from the University of Alberta Folio, 28 April 2000; Vol. 37, Number 16.)

In Alberta, two mobile retinal units with mydriatic cameras travel to 44 First Nations (North American Indian) communities to identify sight-threatening levels of diabetic retinopathy and other eye diseases. Additional testing includes urinalysis, and hemoglobin A1c and cholesterol levels. Nutritional and diabetic counseling is also provided. Visual acuity and intraocular pressures are measured and seven-field, 30-degree digital retina images captured through dilated pupils. Nonsimultaneous stereoscopic pairs of photographs of the disc and macula only are captured, eliminating the need for extra skills to stereo image the peripheral retina. The photography protocol maximizes the benefit of stereopsis for identifying macular edema and neovascularization of the disc. The protocol also minimizes the duration of photography sessions. Once photographs are captured, images and patient information are uploaded to the Web server as encrypted files to be graded by a retinal specialist. Files are protected by two-factor authentication and passwords as images are graded by ophthalmologists with a computer-assisted ETDRS algorithm. Only patients with clinically significant macular edema (CSME) and/or proliferative diabetic retinopathy (PDR) are referred for treatment [14,15]. Once treated, patients are followed over distance by teleophthalmology. Other Canadian telemedicine programs screen for diabetic retinopathy using nonmydriatic digital retinal cameras [16–18].

Some health care organizations contract diabetic retinopathy telemedicine services to commercial enterprises. The Inoveon Corporation of Oklahoma City,

Kaiser referral categories (no referral if less than mild NPDR).

*Rudnisky’s study compared to contact lens biomicroscopy instead of 35 mm.

DR = diabetic retinopathy; NPDR = nonproliferative diabetic retinopathy; PDR = proliferative diabetic retinopathy; CSME = clinically significant macula edema.

1.Fransen enrolled patients consecutively; 27 eyes had PDR; 65 eyes had macular edema.

2.Rudnisky enrolled patients consecutively; 42 patients had CSME in at least one eye.

3.Brusell enrolled patients with an identified range of retinopathy level; 8 eyes had CSME; 9 eyes had PDR.

4.Massin used hard exudates within one disc diameter of the fovea as a surrogate marker of macular edema; 12 patients had CSME; 0 had PDR.

5.Lin found all patients with macular edema screened positive for referral due to retinopathy findings including microaneurysms and hemorrhages in photographs; the number of patients with macular edema was not reported.

382 Diabetes and Ocular Disease

Figure 19.7. Topcon TRC-NW6S internal fixation target. The patient follows the green light as the operator moves the fixation target from one position to the next.

Internal targets are also easier for patients to see and follow than external targets (Fig. 19.7).

Topcon’s IMAGEnet 2000 software constructs a large mosaic from nine digital photographs covering about the same posterior pole retina size as the ETDRS seven fields (Fig. 19.8). Many diabetic patients at UTMB’s Starks Diabetes Center (located on the other side of campus from the department of ophthalmology) benefited from retinal evaluations at Starks. Images taken through small pupils are often too dark or have low contrast. Consequently, image quality suffers as a number of flash photographs are acquired in rapid succession through undilated pupils. For this reason, pupils were pharmacologically dilated. Nine photographs were taken per eye. Comparison of 141 eyes’ wide-angle digital imagery to standard ETDRS seven-field stereo 35-degree slides using the ETDRS nine-step scale protocol found 88% ± 1 step agreement [36].

Other manufacturers such as Canon, Kowa, Nidek and Zeiss also make nonmydriatic cameras, many with similar features to Topcon. Kowa’s nonmydriatic camera uses three internal fixation positions: central, nasal, and temporal. Some nonmydriatic systems can be outfitted with seven internal targets fixated at similar field definitions as ETDRS fields. This should allow grading retinopathy levels that exactly follow ETDRS protocols.