To establish a diagnosis or evaluate the efficacy of treatment for macular disorders, we need methods to evaluate the anatomical and functional changes of these disorders. In this article, we describe several studies that we have conducted for 2 years. In section 1, we report our new methods for making a diagnosis and evaluating visual function in macular disorders. In section 2, we describe our trials of these examination methods in treatment. Here is the summary of our results. In section 1, to examine the structures of the macular area, we used a retinal thickness analyzer (RTA), a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph, HRT), and optical coherence tomography (OCT) to measure retinal thickness and assess retinal microstructures. We compared retinal imaging analysis of various macular diseases obtained with these three instruments. With the RTA, we obtained good three-dimensional macular images displayed on a retinal thickness map, but the retinal thickness map did not demonstrate the thickened retina with dense retinal hemorrhages, and high backscattering from hard exudates might obscure the vitreoretinal interface. The HRT three-dimensional topographic image clearly showed the undulation of the retinal surface. However, it took a relatively long time to obtain the HRT image, and we sometimes could not obtain good topographic images because of fixation movement. Examination with the OCT allows confirmation of the retinal cross-sectional structures, such as retinoschisis or cystoid spaces and the vitreomacular interface, such as vitreous traction, that cannot be detected using other conventional methods with high resolution, but high reflectivity from dense hemorrhages obscured the deeper layers of the retinal structures. Measurement of retinal thickness obtained with both the RTA and OCT is highly reproducible, and there was significant correlation between the retinal thicknesses measured with the two instruments. We believe that these three instruments might contribute significantly to early, accurate diagnosis and better monitoring of the therapeutic effects of vitrectomy for macular diseases. In the future, if these fundus imaging analysis instruments can achieve higher resolution and can analyze three-dimensional retinal images, they will provide better information to clinically evaluate macular diseases. We demonstrated vitreous examination and examination from the retinal surface to the deeper retinal layer at the macular area using a scanning laser ophthalmoscope (SLO). The SLO examination with an argon laser and a large confocal aperture was useful for conducting kinetic examination of the vitreous opacity above the macula. With a diode laser and a ring aperture (dark-field mode), it was possible to examine the retina from the deeper retinal layer to the choroids. On the other hand, the SLO also allows us to conduct a functional examination of fixation. We demonstrated that the referred retinal locus of fixation may change during the follow-up period in patients whose central fixation is impaired due to macular disease, and we showed that the fixation behavior was related to the visual acuity. Therefore, the SLO is an ideal instrument for determining the visual field and the visual acuity before and after treatment in patients with macular disease, because of its precise localization of the examination point by directly observing the fundus and by monitoring fixation behavior. Our new program installed in the SLO allows us to complete the quantitative retinal sensitivity evaluation within 2 minutes, which is difficult to do using a conventional SLO program. Furthermore, we demonstrated for the first time that minute functional changes in the retina can be detected by the SLO under low background illuminance. Such changes cannot be detected under conventional conditions. In addition, the extrafoveal visual acuity of normal subjects and patients with macular disease was studied using this new SLO program. The iso-acuity lines could be illustrated by summarizing these results in normal subjects. The SLO acuity of the horizontal meridian is significantly better than that of the vertical meridian, and even in the nasal area adjacent to the optic disc, an acuity of better than 0.1 could be achieved. To evaluate macular function, we also investigated the blood flow of the choroid (CF), the retina (RF), and the choriocapillaris at the fovea (CCF). We investigated the CF in patients with age-related macular degeneration (AMD) using pulsatile ocular blood flow (POBF) measurements. In patients with exudative AMD, the POBF was significantly lower than in patients with nonexudative AMD or in control subjects. Decreased CF may play a role in the development of choroidal neovascularization in AMD. RF was measured using laser Doppler velocimetry (LDV). (ABSTRACT TRUNCATED)
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Nov 26, 2003
Jan Kerr + 2
Open Access