High resolution imaging of fluorescein patterns in RCS rat retinae and their direct correlation with histology.

To assess the progressive changes in the retinal vascular bed of dystrophic and non-dystrophic Royal College of Surgeons (RCS) rats, retinae, were visualised correlating in vivo fundus fluorescein angiography (FA) with histology. FA was performed in rats aged 5 weeks to 2 years, using a Zeiss confocal scanning laser ophthalmoscope (cSLO). After the final imaging session, a subset of retinae were prepared for flat-mount histology and the vascular bed was visualised using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) staining. While non-dystrophic rat retinae showed no substantive changes in vascular patterns with age and no demonstrable fluorescein leakage up to at least 1 year, dystrophic rat retinae showed abnormal vascular formations, demonstrable on FA and NADPH-d staining, which could be correlated in single retinae. Hyperfluorescent spots and late angiographic leakage were evident beginning at 10 weeks and progressed in severity with time: they were coincident in distribution with abnormal histological vascular complexes. The ability to monitor the same retina serially makes this approach a valuable tool for studying the dynamics of vascular change in the diseased retina, not only during the course of degeneration but also when assessing efficacy of potential therapeutic approaches.

Retinal pigment epithelium translocation and central visual function in age related macular degeneration: preliminary results.

PURPOSE: To test the feasibility of a new surgical technique, and to assess visual function over the translocated retinal pigment epithelium (RPE) cells in patients operated upon for subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD). MATERIALS AND METHODS: Six patients presenting previously untreated exudative AMD underwent surgical excision of the subfoveal CNV with RPE translocation and were followed from 1 to 10.5 months. The surgery consisted of a standard three port pars plana vitrectomy (TPPPV), excision of the CNV and RPE translocation. Pre and post-operative ocular examination included best-corrected visual acuity measurement, fundus color stereo photography and fundus fluorescein angiography. Optical coherence tomography (OCT) and confocal laser scanning ophthalmoscopy (cLSO) were performed post-operatively. A cross fixation target and a single-point flashing light were projected on different areas of the posterior pole using a cLSO. Photopic 10-2 perimetry, photopic fine matrix mapping, cLSO microperimetry were also performed pre and post-operatively in four patients. OCT cross-sectional scans and cLSO RPE autofluorescence were recorded to detect the presence of viable translocated RPE. Visual acuity, fixation, photopic 10-2 perimetry, photopic fine matrix mapping and cLSO microperimetry were tested for the presence of central visual function. RESULTS: RPE could be effectively translocated at the time of CNV removal from the edge of the RPE defect to a subfoveal location. OCT showed the translocated RPE as an area of increased optical reflectivity with optical shadowing external to it. cLSO showed autofluorescence of the translocated RPE. The cross fixation target was seen when projected on the translocated RPE. During eccentric fixation, the patients could see a flashing point-target projected on the translocated RPE. Photopic 10-2 perimetry, photopic fine matrix mapping and cLSO microperimetry showed presence of central visual function. CONCLUSIONS: The authors propose that translocation of RPE at the time of CNV removal, from the edge of the RPE defect to a subfoveal location, may have a role in the surgical management of AMD.

Quantitative evaluation of fundus autofluorescence imaged "in vivo" in eyes with retinal disease.

AIM: To describe a new method of evaluating the topographic distribution of fundus autofluorescence in eyes with retinal disease. METHODS: Images of fundus autofluorescence were obtained in five patients and 34 normal volunteers using a confocal scanning laser ophthalmoscope (cSLO). To evaluate the topographic distribution of fundus autofluorescence throughout the posterior pole a rectangular box, 10 x 750 pixels, was used as the area of analysis. The box was placed, horizontally, across the macular region. The intensity of fundus autofluorescence of each pixel within the rectangular box was plotted against its degree of eccentricity. Profiles of fundus autofluorescence from patients were compared with those obtained from the age matched control group and with cSLO images. RESULTS: Profiles of fundus autofluorescence appeared to represent the topographic distribution of fundus autofluorescence throughout the posterior pole appreciated in the cSLO images, and allowed rapid identification and quantification of areas of increased or decreased fundus autofluorescence. CONCLUSIONS: Fundus autofluorescence profiles appear to be useful to study the spatial distribution of fundus autofluorescence in eyes with retinal disease.

Reproducibility of fundus autofluorescence measurements obtained using a confocal scanning laser ophthalmoscope.

AIM: To evaluate the reproducibility of the background fundus autofluorescence measurements obtained using a confocal scanning laser ophthalmoscope. METHODS: 10 normal volunteers and 10 patients with retinal disease were included in the study. One eye per subject was chosen randomly. Five images of the same eye of each individual were obtained, after pupillary dilatation, by two investigators using a confocal scanning laser ophthalmoscope. Background fundus autofluorescence was measured at 7 degrees temporal to the fovea in normal volunteers and between 7 and 15 degrees temporal to the fovea in patients. Within session reproducibility of the measurements obtained by each investigator and interobserver reproducibility were evaluated. RESULTS: For investigator 1 the median values of fundus autofluorescence obtained were 31.9 units for normal volunteers and 27.3 units for patients. The median largest differences in readings in normal volunteers was 5.7 units (range 1.4-13.5 units) and in patients 4.2 units (1.5-15.1 units). For investigator 2 the median values of fundus autofluorescence obtained were 28.9 units for normal volunteers and 27.4 units for patients. The median largest difference in readings in normal volunteers was 3.6 units (2.7-11.7 units), and in patients 4.1 units (1.5-9.3 units). The median interobserver difference in readings in normal volunteers was 3.3 units and for patients 6.6 units. The median greatest interobserver difference in measurements obtained for normal volunteers was 8.8 units (8.4-23.0 units) and for patients 11.1 units (7.1-40.8 units). CONCLUSION: Within session reproducibility of the measurements of background fundus autofluorescence was satisfactory. Although interobserver reproducibility was moderate, the variability of the measurements of fundus autofluorescence between observers appears to be small when compared with variation in fundus autofluorescence with age and disease.