Digital imaging and microtexture analysis of the nerve fiber layer.

PURPOSE: To describe the design of a digital retinal nerve fiber layer (RNFL) imaging techniques and present a new approach to measure the differences in RNFL patterns. METHODS: A digital camera body is connected to a wide-angle camera to obtain images of the RNFL, which are displayed in workstations throughout the clinic. In the on-line archive, images in Joint Photographics Experts Group (JPEG) format (100 KB per frame) are used. The hypothesis that changes in RNFL structure can be seen as changes in the microtexture of digital images was tested using an information theoretical approach (Kullback Information Distance, KID). A large KID value indicates a large difference, and a small KID value indicates a small difference in microtexture between the two regions. The material of this pilot study consists of 9 patients with glaucoma, 8 patients with ocular hypertension, and 7 normal subjects. RESULTS: The median KID value in the glaucoma group was 3.5, compared with the median KID values of 0.6 in the control groups. Although a trend could be seen in the measured values, because of a small sample size, the differences were not statistically significant. Five of 24 (21%) KID values overlapped between the glaucomatous group and the other two groups. CONCLUSION: Although digital imaging produces good quality RNFL images, further research is needed to establish minimum accepted specifications for digital imaging. In this pilot study, only the microtexture of the RNFL was measured in digital images. In the future, the approach can be expanded to include also properties of macrotexture and full color palette.

The application of teleophthalmology in examining patients with glaucoma: a pilot study.

PURPOSE: To test the feasibility of teleophthalmology applications in examining patients with glaucoma, test its use for training purposes in an ophthalmology residency program and as a consultation link between primary healthcare unit and university eye clinic, and to introduce a preliminary model for economic assessment of telemedicine application in ophthalmology. METHODS: A video slit-lamp, an automated perimeter, a nonmydriatic fundus camera and a videoconferencing system were installed in a healthcare center in a rural area. Twenty-nine patients with glaucoma were examined in the rural healthcare center instead of the university eye clinic. A control group consisted of 41 glaucoma patients examined at the eye clinic one year earlier. An ophthalmic resident examined the patients together with the local general practitioner. An interactive video consultation was created with the university glaucoma clinic using ISDN connections and special application software. RESULTS: Both patient groups were equally satisfied with the ophthalmic service. Nearly all patients in the telemedicine group (96%) wanted to have their next visit in their own healthcare center instead of the university clinic. The most important reasons were reduction in traveling (97%), costs (92%), and time (92%). The costs of the telemedicine and conventional visits were equal, but decreased traveling saved $55 per visit. However, the quality of the images obtained in the remote center was poorer than that of the images obtained at the university clinic. CONCLUSION: The results of this pilot study indicate that further research with a larger number of patients is warranted to evaluate both methods, technology, and economics of teleophthalmology.