Akitoshi Yoshida

Pulsatile ocular blood flow study: decreases in exudative age related macular degeneration

BACKGROUND Pulsatile ocular blood flow (POBF) is a parameter for evaluating choroidal blood flow. POBF in the patients with non-exudative and exudative age related macular degeneration (AMD) was investigated. METHODS POBF, pulse amplitude (PA), systolic and diastolic blood pressures, intraocular pressure (IOP), refractive error, and axial length were compared among 10 patients with non-exudative AMD, 11 patients with exudative AMD, and 69 age matched controls. A Langham OBF computerised tonometer was used with the participants in the sitting position to measure POBF and PA. RESULTS No significant differences were found in age, systolic and diastolic blood pressures, IOP, or refractive error between patients with exudative and non-exudative AMD and the control subjects. In the patients with exudative AMD the POBF (median, 372.7 μl/min) and PA (median, 1.2 mm Hg) were significantly lower than in the patients with non-exudative AMD (median, 607.0 μl/min (p = 0.02) and 2.2 mm Hg (p = 0.04), respectively) and control subjects (median, 547.4 μl/min (p = 0.01) and 2.0 mm Hg (p = 0.01), respectively). CONCLUSIONS These data show that the POBF and PA in the patients with exudative AMD are lower than in the patients with non-exudative AMD and normal subjects. Decreased choroidal blood flow may have a role in the development of choroidal neovascularisation in AMD.

Retinal thickness measurements with optical coherence tomography and the scanning retinal thickness analyzer.

Purpose To assess the reproducibility of retinal thickness measurements in normal subjects and to compare foveal thickness using optical coherence tomography (OCT) and the scanning retinal thickness analyzer (RTA). Methods Two examiners performed foveal thickness measurements in 24 eyes of 12 healthy subjects using both OCT and the scanning RTA. Intraclass correlation coefficients (ICC) (intra-examiner and inter-examiner) were calculated for the paired foveal thickness measurements obtained with each instrument. Results The average foveal thicknesses measured with OCT and the scanning RTA were 155.1 ± 14.9 &mgr;m and 107.8 ± 18.6 &mgr;m, respectively. The intra-examiner ICCs from the two sessions using the OCT and the scanning RTA were 0.99 and 0.78 and 0.89 and 0.99, respectively. The inter-examiner ICCs of the OCT and the scanning RTA were 0.99 and 0.99, respectively. There was a significant correlation between the foveal thickness measurements with these two instruments (R2 = 0.629, P < 0.0001). Conclusion The foveal thicknesses measured using OCT and the scanning RTA in healthy subjects agreed with the previously reported data on foveal thickness. Both instruments can reproducibly quantitate foveal thickness.

Scotoma and Fixation Patterns Using Scanning Laser Ophthalmoscope Microperimetry in Patients With Macular Dystrophy

PURPOSE We used scanning laser ophthalmoscope microperimetry to evaluate the retinal scotoma and the fixation points in the patients with macular dystrophy. METHODS We studied 10 eyes of five patients with macular dystrophy (three patients with cone dystrophy and two patients with Stargardt disease). The mean patient age was 37 years (range, 13 to 64 years). An estimation of scotoma and fixation points on the retina was performed using scanning laser ophthalmoscope microperimetry. RESULTS All 10 eyes (100%) had one of two types of dense scotoma: type one was a dense ring scotoma (five eyes, 50%), and type two was a dense central scotoma (five eyes, 50%) that included the center of the fovea. In all eyes with a dense ring scotoma, the fixation points were stable and did not shift. In all eyes with a dense central scotoma, the fixation shifted. The logarithm of minimal angle of resolution of the visual acuity in the eyes with the dense central scotoma was significantly worse than that of eyes with the dense ring scotoma type (P =.005). CONCLUSIONS Scanning laser ophthalmoscope microperimetry findings demonstrate two types of dense scotoma (dense ring scotoma and dense central scotoma) in the patients with macular dystrophy. The two types of dense scotoma affect the shifting of the fixation points and the stability of fixation and may result in the difference in visual acuity in the patients with macular dystrophy.

Factors affecting pulsatile ocular blood flow in normal subjects

BACKGROUND The factors that influence pulsatile ocular blood flow (POBF) were evaluated in normal subjects. METHODS POBF was measured in 80 normal subjects using Langham OBF computerised tonometry. The effect of age, systolic and diastolic blood pressure, refractive error, intraocular pressure, and axial length on POBF was evaluated using multiple regression analysis. RESULTS The mean (SD) POBF value was 593.3 (203.6) μl/min (range 290.7–1201.6). Of all the independent variables in the model, only the axial length was statistically significant (p=0.008). The regression coefficient was negative, indicating that the axial length decreased with increasing POBF. CONCLUSIONS These data suggest that, in normal subjects, the POBF decreases as axial length increases. Choroidal blood flow may decrease as the axial length increases. The axial length may therefore be a major factor affecting POBF.

Inhibitory effect of losartan on laser-induced choroidal neovascularization in rats

PURPOSE To investigate the inhibitory effects of losartan, an angiotensin receptor antagonist, on angiogenesis in a rat model of laser-induced choroidal neovascularization. METHODS Experimental study. Fifteen Brown-Norway male rats received losartan (approximately 5 mg/kg/d) in drinking water, and 15 Brown-Norway male rats received unsupplemented drinking water 1 week before photocoagulation, and it was continued to the end of the study. Two weeks after intense laser photocoagulation, choroidal neovascularization was evaluated by fluorescein angiography and histopathologic evaluation. RESULTS The incidence of choroidal neovascularization formation was 99.5 +/-.2% (mean +/- standard deviation) in controls and 72.5 +/- 8.8% in losartan-treated rats (P <.01). Quantitative morphometric assessment revealed mean choroidal neovascularization lesion thickness of 54 and 44.8 microm, respectively, in controls and losartan-treated rats (P <.01). CONCLUSION Losartan seems to inhibit development of laser-induced choroidal neovascularization. Angiotensin receptor antagonists may be useful as prophylaxis against choroidal neovascularization associated with age-related macular degeneration.

Branch Retinal Vein Occlusion in a Japanese Patient with Neurofibromatosis 1

BACKGROUND To report an Asian patient with branch retinal vein occlusion secondary to neurofibromatosis 1. CASE A 64-year-old woman presented with a loss of vision in her right eye of 9-month duration. A diagnosis of neurofibromatosis 1 was made. A general medical examination showed no abnormalities except the signs of neurofibromatosis 1. OBSERVATIONS Fundus examination of the right eye revealed irregularities of the venous caliber, partial sheathing of the corresponding vein and macular edema. Multiple dilated and tortuous collateral channels and an arteriovenous communication bridged the perfused and nonperfused retina. Fundus examination of the left eye showed a tortuous vein in the temporal region of the fovea. Fluorescein angiography of the right eye confirmed delayed filling in a superotemporal artery and in the corresponding vein. The temporal region of the fovea had large areas of capillary loss. The collaterals were tortuous and mimicked a neovascularization. Fluorescein angiography of the left eye confirmed that the vein in the temporal part of the fovea was tortuous and not leaking. A diagnosis of branch retinal vein occlusion of the superotemporal vein was made. CONCLUSIONS Neurofibromatosis 1 should be considered in the differential diagnosis of retinal vascular occlusive disease without other risk factors.

Effect of acetazolamide on outward permeability of blood-retina barrier using differential vitreous flyorophotometry.

Purpose. To measure fluorescein (F) and fluorescein monoglucuronide (FG) concentrations in the vitreous and evaluate the effect of acetazolamide (AZM) on the outward permeability of the blood-retina barrier (BRB) using differential vitreous fluorophotometry (DVF). Methods. DVF was performed 180 minutes after intravenous injection of AZM (5 mg/kg) and 50 mg of sodium fluorescein in six rabbits (AZM group). DVF also was performed in six rabbits injected intravenously with only 50 mg of sodium fluorescein (control group). The F/FG ratio was calculated based on the concentrations of F and FG obtained by DVF. DVF also was performed 180 minutes after 50 mg of intravenous injection of sodium fluorescein in five rabbits given probenecid (150 mg/kg) intraperitoneally (probenecid group). Results. The average F/FG ratio was 0.36 ± 0.17 (range, 0.22–0.66) in the AZM group, which was significantly smaller than the control value of 0.74 ± 0.22 (range, 0.50–1.60). The average F/FG ratio at 180 minutes after injection was 1.51 ± 0.46 (range, 0.94–2.00) in the probenecid group, which was significant higher (p < 0.05) than that of the AZM or control group. Conclusions. This study showed that the F/FG ratio might be a good indicator of the estimated outward permeability of the BRB using DVF and that AZM may accelerate the outward active transport function of the BRB.

Dynamic observation of selective accumulation of a photosensitizer and its photodynamic effects in rat experimental choroidal neovascularization.

Purpose The authors investigated the selective accumulation of a photosensitizer, ATX-S10(Na), in experimental choroidal neovascularization (CNV) in rats using a highly sensitive colorchromatic charge coupled device (CCD) camera. Methods To detect the development of experimental CNV in 30 rats, the animals were followed weekly with simultaneous fluorescein and indocyanine green angiography. After injecting ATX-S10(Na), the authors detected fluorescence from the photosensitizer using a highly sensitive color CCD camera. The camera was connected to a surgical microscope, under which rat fundi were observed through a coverglass in contact with the cornea. The retinas were excited with 405–435 nm light, and the light emitted from the photosensitizer passed through a 680-nm bandpass filter before being detected by the CCD camera. Results Immediately after injection, fluorescence appeared in the retinal vessels and then the entire retina. Thirty minutes postinjection, the intensity of the fluorescence was still strong from the whole retina, and the CNV was not detected. One hour after injection, retinal fluorescence was weak but still observable; 1.5 hours postinjection, retinal fluorescence was undetectable but fluorescence was strong from the CNV. Under the optimum therapeutic conditions, CNV was effectively occluded. Conclusion ATX-S10(Na) selectively accumulates in the CNV in rats. The optimum therapeutic timing is approximately 1.5 hours postinjection of the dye in this CNV model.

Three-Dimensional Analysis of Macular Diseases With a Scanning Retinal Thickness Analyzer and a Confocal Scanning Laser Ophthalmoscope

OBJECTIVE To compare three-dimensional analysis of macular diseases obtained using the scanning retinal thickness analyzer (RTA) with that obtained using the confocal scanning laser ophthalmoscope, Heidelberg Retina Tomograph (HRT). PATIENTS AND METHODS Both the RTA and the HRT were used to examine 50 eyes of 36 patients with diabetic macular edema, macular edema following branch retinal vein occlusion, age-related macular degeneration, and idiopathic macular holes. RESULTS In most macular diseases, the retinal thickness map constructed using the RTA agreed with the image obtained with the HRT. The two maps were not consistent with each other, however, in patients with dense retinal hemorrhages and with extrafoveal fixation. CONCLUSIONS Although both the RTA and the HRT give additional information to clinically evaluate macular diseases, they do have limitations. The discrepancy between these two analyses in some specific macular pathologies might be caused by the different wavelengths of the laser beam and the different methodologies used to scan the retina.

Variations of Weiss's ring.

Background Weiss’s ring is an important index for diagnosing a posterior vitreous detachment (PVD). The authors studied the configurations of Weiss’s ring because the ring has several variations. Methods Weiss’s ring was examined biomicroscopically in 223 eyes with PVD and documented videographically using a scanning laser ophthalmoscope. The configurations of Weiss’s ring were classified into four groups: a complete ring, a partial ring, a ball-like opacity, and a hole without a ring. Results In the 223 eyes with PVD, Weiss’s ring was categorized as a complete ring in 63 eyes (28.3%), a partial ring in 128 eyes (57.4%), a ball-like opacity in 17 eyes (7.6%), and a hole without a ring in 15 eyes (6.7%). A complete ring was observed in 8 (57.1%) of 14 eyes with hyperopia (+3 diopters or more), in 25 (28.7%) of 87 eyes with emmetropia (between −1 and +1 diopter), and in 10 (16.1%) of 62 eyes with myopia (−3 diopters or more). Six months after the initial examinations, the contour of Weiss’s ring remained unchanged in 86 (96.6%) of 89 eyes with fresh PVD. Conclusions Scanning laser ophthalmoscope is a useful tool for observing Weiss’s ring. A “classic” annular opacity around a hole in the prepapillary posterior vitreous cortex represents less than one third of the configurations of Weiss’s ring, indicating that the term “ring” is erroneous.