Suguru Konno

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.

ROLE OF THE VITREOUS IN CENTRAL RETINAL VEIN OCCLUSION

Purpose The role of the vitreous in eyes with CRVO and its relationship to neovascularization and macular edema, in particular, were investigated. Methods A retrospective chart review of the vitreous condition of 136 patients (136 eyes) with CRVO was performed. Based on fluorescein angiography findings and color photographs, eyes with CRVO were classified as either ischemic or nonischemic. Results In ischemic cases, retinal or optic disc neovascularization or both developed in 8 (57%) of 14 eyes with no or partial posterior vitreous detachment (PVD) at the final examination. The prevalence of neovascularization was significantly higher than in eyes with complete PVD (0%, 0 of 38) at the final examination (P < 0.01). No significant relationship was found between iris neovascularization development and the vitreous condition or between the prevalence of PVD and macular edema. In nonischemic eyes, the prevalence of no PVD or partial PVD with vitreomacular attachment was significantly higher in those with macular edema (76%, 25 of 33) than in eyes without (25%, 13 of 51) at the final examination (P < 0.01). Conclusion Complete PVD may protect against retinal or optic disc neovascularization in eyes with severe CRVO. Vitreomacular attachment may cause persistent macular edema in eyes with mild CRVO.

Retinal detachment associated with a macular hole in severely myopic eyes

PURPOSE To investigate factors associated with extensive retinal detachment in severely myopic eyes with a macular hole. METHOD Fifty-two consecutive eyes with a macular hole and severe myopia were retrospectively studied. RESULTS An extensive retinal detachment, defined as extending beyond the cuff of subretinal fluid, was observed in 37 eyes (71%). Extensive retinal detachment developed in 36 (95%) of 38 eyes with a posterior staphyloma and in one (7%) of 14 eyes without a posterior staphyloma (P<.0001). Extensive retinal detachment also developed in 32 (89%) of 36 eyes with complete posterior vitreous detachment and in five (31%) of 16 eyes without posterior vitreous detachment (P<.0001). CONCLUSION Posterior staphyloma rather than anteroposterior vitreomacular traction may contribute to the development of retinal detachment associated with a macular hole in severely myopic eyes.

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.

Prognosis of Stage 2 Macular Holes

PURPOSE We ascertained the natural course of stage 2 idiopathic macular holes to determine better treatment possibilities. METHODS We reviewed 48 eyes with stage 2 idiopathic macular holes and followed them up for more than two years. At each examination, best-corrected Snellen visual acuity was measured by a physician masked to the hypothesis of the study. RESULTS Stage 2 lesions progressed to stage 3 or 4 during the follow-up period in 32 (67%) and 14 (29%) of 48 eyes, respectively; two eyes (4%) remained in stage 2. In 41 (85%) of 48 eyes, the hole size enlarged during the follow-up: 32 (94%) of 34 eyes had vitreomacular attachment and nine (64%) of 14 eyes had vitreomacular separation at the final examination, for a statistically significant difference in prevalence (P = .03). Visual acuity decreased two or more Snellen lines during the follow-up period in 34 (71%) of 48 eyes, the prevalence of which was significantly higher in eyes with vitreomacular attachment at the final examination (28 of 34, 82%) than in eyes with vitreomacular separation at the final examination (six of 14, 43%) (P = .01). CONCLUSION Even though vitreomacular separation may improve the prognosis of a macular hole, stage 2 lesions usually will develop an enlarged hole and decreased visual acuity.

Retinal blood flow changes in type I diabetes. A long-term, follow-up study

PURPOSE The authors previously reported that blood speeds in the retinal arteries were significantly lower in patients with type I diabetes than in controls without diabetes. The purpose of this long-term, follow-up study was to characterize the natural course of changes in blood speed and blood flow in these patients. METHODS Twenty-four patients were followed up with serial annual measurements of the blood flow in a temporal retinal artery using the bidirectional laser Doppler technique and monochromatic photography. The follow-up period ranged from 2 to 6 years (mean, 3.8 years). Using standardized color fundus photography and fluorescein angiography, a retinopathy score was generated for each eye studied. Linear regression analysis was used to compute the slope of the change in retinal blood flow for each patient during the follow-up period. RESULTS Retinal blood flow slopes were negative in 15 patients and positive in 9 patients. Multiple linear regression analysis showed that the retinal blood flow slopes were significantly related to the retinal blood flow measured at entry to the study and to the median duration of diabetes during the follow-up period (R2 = 0.56; P = 0.0002). There was a positive correlation between the retinal blood flow slopes and the median retinopathy score during the follow-up period (P = 0.47; P = 0.02). CONCLUSIONS As duration of diabetes becomes longer and retinopathy becomes more severe, there is a transition from negative to positive retinal blood flow slopes. This bimodal relationship between the change in retinal blood flow and the duration of diabetes reflects the complex pathologic alterations that occur in the diabetic retina.

Retinal detachment and retinoschisis detected by optical coherence tomography in a myopic eye with a macular hole.

The authors describe a myopic patient with a full-thickness macular hole that was accompanied by both retinal detachment and retinoschisis. A 51-year-old woman presented with a localized retinal elevation of three disc diameters around the macular hole in a myopic eye. Optical coherence tomography (OCT) showed features of both retinal detachment and retinoschisis. After vitreous surgery and postoperative intraocular gas tamponade, the macular elevation resolved, and separation of the neurosensory retina from the retinal pigment epithelium band disappeared on the OCT images. OCT is a useful tool for examining macular conditions associated with a macular hole in myopic patients.

Optic nerve head circulation in untreated ocular hypertension.

AIMS--The laser Doppler technique was used to compare the capillary blood speed measured at localised sites of the optic nerve head in stable, untreated ocular hypertensive patients with that measured in healthy normal subjects. The stereophotogrammetric technique was also used to measure the retinal nerve fibre layer thickness at the disc margin in the eyes of the patients. METHODS--Doppler broadening measurements were made at superior and inferior temporal disc sites in 18 eyes of 10 ocular hypertensive patients and in 12 eyes of seven age and sex-matched normal subjects. RESULTS--On average, Doppler broadening and, hence, capillary blood speed were significantly higher (p = 0.018) in the patients than in the normal subjects. The largest values of Doppler broadening in the patients were measured at sites adjacent to the thinnest retinal nerve fibre layer. Linear regression analysis showed a significant inverse relation (p = 0.0004) between Doppler broadening and nerve fibre layer thickness in left eyes, and a nearly significant relation (p = 0.06) in right eyes. At temporal sites of the optic nerve head there is a compensatory relation between a thinning nerve fibre layer and a locally increasing blood supply to the optic nerve head. CONCLUSION--Together with previous observations of fluorescein filling defects in similar patients, these results indicate that there is spatial heterogeneity of blood flow in the optic nerve head in stable, untreated ocular hypertensive patients.

OCT in successful surgery of retinal detachment associated with optic nerve head pit.

The authors describe the course of a patient with retinal detachment associated with optic nerve head pit for whom optical coherence tomography (OCT) was performed before and after vitrectomy and gas tamponade. An 18-year-old woman presented with macular elevation and a lamellar macular hole associated with optic nerve head pit. OCT showed that the retinal elevation consisted of both separation of the inner and outer retinal layers and detachment of the outer layers from the retinal pigment epithelium. After vitreous surgery and postoperative intraocular gas tamponade, the macular elevation gradually resolved, and OCT showed that improvement in central vision corresponded with flattening of the outer layer detachment in the fovea. OCT is a useful tool for monitoring the therapeutic effect of vitrectomy and gas tamponade for retinal detachment associated with optic nerve head pit.