Contributions of Sodium-Hydrogen Exchanger 1 and Mitogen-Activated Protein Kinases to Enhanced Retinal Venular Constriction to Endothelin-1 in Diabetes

Diabetes elevates endothelin-1 (ET-1) in the vitreous and enhances constriction of retinal venules to this peptide. However, mechanisms contributing to ET-1-induced constriction of retinal venules are incompletely understood. We examined roles of sodium-hydrogen exchanger 1 (NHE1), protein kinase C (PKC), mitogen-activated protein kinases (MAPKs), and extracellular calcium (Ca²⁺) in retinal venular constriction to ET-1 and the impact of diabetes on these signaling molecules. Retinal venules were isolated from control pigs and pigs with streptozocin-induced diabetes for in vitro studies. ET-1-induced vasoconstriction was abolished in the absence of extracellular Ca²⁺ and sensitive to c-Jun N-terminal kinase (JNK) inhibitor SP600125 but unaffected by extracellular signal-regulated kinase (ERK) inhibitor PD98059, p38 kinase inhibitor SB203580, or broad-spectrum PKC inhibitor Gö 6983. Diabetes (after 2 weeks) enhanced venular constriction to ET-1, which was insensitive to PD98059 and Gö 6983 but was prevented by NHE1 inhibitor cariporide, SB203580, and SP600125. In conclusion, extracellular Ca²⁺ entry and activation of JNK, independent of ERK and PKC, mediate constriction of retinal venules to ET-1. Diabetes activates p38 MAPK and NHE1, which cause enhanced venular constriction to ET-1. Treatments targeting these vascular molecules may lessen retinal complications in early diabetes.

Central retinal vascular trunk deviation in unilateral normal-tension glaucoma

Purpose

To investigate whether the position of the central retinal vascular trunk (CRVT), as a surrogate of lamina cribrosa (LC) offset, was associated with the presence of glaucoma in normal-tension glaucoma (NTG) patients.

Methods

The position of the CRVT was measured as the deviation from the center of the Bruch’s membrane opening (BMO), as delineated by spectral-domain optical coherence tomography imaging. The offset index was calculated as the distance of the CRVT from the BMO center relative to that of the BMO margin. The angular deviation of CRVT was measured with the horizontal nasal midline as 0° and the superior location as a positive value. The offset index and angular deviation were compared between glaucoma and fellow control eyes within individuals.

Results

NTG eyes had higher baseline intraocular pressure (P = 0.001), a larger β-zone parapapillary atrophy area (P = 0.013), and a larger offset index (P<0.001). In a generalized linear mixed-effects model, larger offset index was the only risk factor of NTG diagnosis (OR = 31.625, P<0.001). A generalized estimating equation regression model revealed that the offset index was larger in the NTG eyes than in the control eyes for all ranges of axial length, while it was the smallest for the axial length of 23.4 mm (all P<0.001).

Conclusions

The offset index was larger in the unilateral NTG eyes, which fact is suggestive of the potential role of LC/BMO offset as a loco-regional susceptibility factor.

RELATION BETWEEN FLUORESCEIN ANGIOGRAPHIC AND SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY FINDINGS OF BLOOD FLOW TURBULENCE AT ARTERIOVENOUS CROSSINGS IN THE RETINA

PURPOSE

To examine retinal blood flow at arteriovenous crossings using spectral-domain optical coherence tomography (SD-OCT).

METHODS

Retrospective observational case series of 11 arteriovenous crossings in 10 eyes examined by SD-OCT and fluorescein angiography on suspicion of manifest or imminent branch retinal vein occlusion.

RESULTS

Fluorescein angiographic evidence of turbulence was seen at 5 of 11 arteriovenous crossings, whereas laminar angiographic flow was intact at the crossing and downstream thereof at the remaining 6 crossings. On SD-OCT, chaotic reflectivity patterns were seen at the point of crossing and downstream thereof in all 5 cases with angiographic turbulence, whereas an intravascular trilayer SD-OCT pattern consistent with laminar flow was seen throughout the examined course of the vein in the eyes with laminar angiographic flow.

CONCLUSION

We examined retinal blood flow at and near arteriovenous crossings and found that SD-OCT may rival fluorescein angiography in the ability to demonstrate turbulent venous blood flow.

Color Doppler Imaging in Uveitis

PURPOSE

To evaluate the vascular hemodynamic changes that can be detected with color Doppler imaging (CDI) in diagnosis, differential diagnosis and prognosis of uveitis with different etiologies including Behçet's disease.

METHODS

Four groups consisting of healthy volunteers, uveitis patients with different etiologies and Behçet's disease patients with and without ocular involvement were examined by CDI. Central retinal artery (CRA), posterior ciliary artery (PCA), ophthalmic artery (OA) and central retinal vein (CRV) flow velocities and vascular resistances were measured prospectively by a radiologist blinded to the presence and etiology of uveitis.

RESULTS

The peak systolic and end-diastolic velocities in CRA and PCA in Behçet's disease with ocular involvement were significantly lower than all other groups (p < 0.001). Peak systolic and end-diastolic velocities in CRA were lower than the control group in Behçet's disease patients without ocular involvement (p < 0.001) but there were no differences in PCA and OA flow velocity (p > 0.05). In the uveitis group, CRA and CRV flow velocities were significantly lower than in the control group (p < 0.001).

CONCLUSIONS

According to our results, uveitis in Behçet's disease is associated with significant reductions of CRA and PCA flow velocities when compared with other types of uveitis and healthy subjects. In cases without ocular involvement, CRA flow velocities were lower than the control group, but there were no real differences in the PCA and OA values. This suggests that vasculitic involvement of PCA is more specific to Behçet's disease and occurs later in the course of the disease. The results also suggest that it may be possible to detect and follow hemodynamic changes in Behçet's disease with CDI before clinical findings of ocular involvement become evident.

Effects of Hypertension on the Retinal Vein Width at the Retinal Arteriovenous Crossings

Purpose

The study was designed to quantify retinal vein width changes at the arterio-venous crossing and to evaluate the effects of hypertension on vein widths at “vein posterior to the artery” (VPA) and “vein anterior to the artery” (VAA) crossings.

Methods

The width of the retinal veins was measured at points before and after the arterio-venous crossings by a computerized image analysis system in ten normal subjects and 35 hypertensive patients. Retinal vein width changes at fixed intervals from the arterio-venous crossing points, both VAA and VPA, were measured as a function of the stage of the hypertensive retinopathy in the subjects.

Results

Mean retinal vein width showed significant (p<0.05) narrowing at VPA crossings at stages 2,3 and 4 of hypertensive retinopathy. For the VAA crossings, there was no significant decrease in the width of the vein at any stage. There was no significant narrowing of the vein at VPA crossings in normal subjects or in stage 0 and stage 1 hypertensive retinopathy patients.

Conclusions

The decrease in the width of the retinal vein in stages 2, 3 and 4 hypertensive retinopathy patients at VPA crossings can cause turbulence in blood flow, leading to intimal damage and occlusion. The absence of narrowing may explain the low incidence of branch retinal vein occlusions at VAA crossings.

Morphologic and Functional Retinal Vessel Changes in Branch Retinal Vein Occlusion: An Optical Coherence Tomography Angiography Study

PURPOSE

The present study aimed to investigate the morphology of the retinal vasculature in eyes with branch retinal vein occlusion (BRVO) using optical coherence tomography (OCT) angiography.

DESIGN

Observational case series.

METHODS

Fluorescein angiography (FA) and OCT angiography were used to examine macular area and the retinal vasculature at the affected arteriovenous (AV) crossing in 46 patients with BRVO.

RESULTS

FA revealed that the affected AV crossing pattern involved arterial overcrossing in 23 eyes (50.0%) and venous overcrossing in 11 eyes (23.9%). However, FA failed to detect the crossing pattern in 10 eyes (21.7%). OCT angiography was significantly more effective for identification of the AV crossing pattern than FA (44 eyes; 95.7%; P = .013). The number of eyes with venous overcrossing detected via OCT angiography (20 eyes, 43.5%) was also higher than that detected via FA (P = .047). OCT angiography revealed that venous narrowing (25.5 ± 21.1 μm) was significantly greater in instances of venous overcrossing than in those of arterial overcrossing (46.4 ± 23.7 μm, P = .005). Macular nonperfusion areas (NPAs) were larger in eyes with venous overcrossing than in those with arterial overcrossing (P = .011 for superficial plexus, P = .049 for deep plexus). The peripheral NPA was significantly larger in eyes with venous overcrossing (65.1 ± 35.3 disc area [DA]) than in those with arterial overcrossing (17.2 ± 24.1 DA; P < .001).

CONCLUSIONS

Our findings suggest that BRVO characterized by venous overcrossing may be more prevalent than previously reported, and that there is a significant association between NPA size and AV crossing pattern.

Does Glaucoma Share Common Pathogenesis with Branch Retinal Vein Occlusion?

Background

To evaluate the observed prevalence and the optic nerve head (ONH) characteristics of normal tension glaucoma (NTG)-suspect eyes in branch retinal vein occulusion (BRVO) eyes in Korean population.

Methods

This was a retrospective observational study. We investigated 445 BRVO eyes that were diagnosed in the retina clinic of Samsung Medical Center between March 2005 and December 2011. The observed prevalence of NTG-suspect in BRVO eyes was evaluated compared to the previous population based study. In addition, NTG-suspect cases in BRVO were divided into three groups based on the characteristics of optic disc morphology.

Results

In 445 BRVO eyes, 30 eyes were excluded from the present study. In 415 BRVO eyes, 4.3% (18 eyes) (95% confident interval [CI], 2.4–6.3%) were diagnosed with suspect glaucoma and this is not significantly different from the result in the general Korean population (P = 0.09). We classified the NTG-suspect eyes into three groups such as disc rim notching and thinning type (Group 1; 55.6%), optic cup-sited hemorrhage type (Group 2; 16.7%) and disc rim thinning and pallor type (Group 3; 27.8%). NTG-suspect in the fellow eye were only found in group 1 (80%) and group 2 (67%), but not in group 3 (P = 0.01).

Conclusions

BRVO and glaucoma seem to have no common vascular pathogenesis in consideration of the prevalence of NTG-suspect in BRVO eyes compared to general Korean population.

Optical Coherence Tomography Angiography of Retinal Vein Occlusion

Retinal vein occlusion is the second most common cause of retinal vascular disease after diabetic retinopathy and is a frequent cause of significant vision loss and associated morbidity. Currently, fluorescein angiography is the gold standard for imaging of the retinal and choroidal vasculature. However, this imaging modality is invasive, involving the use of an intravenous contrast agent that can cause systemic side effects and rarely, anaphylaxis. Optical coherence tomography angiography is a noninvasive, depth-resolved imaging modality that allows for the appreciation of spatial relationships of fundus vessels and enables detailed en face visualization of the superficial and deep retinal vasculature separately without the risk of adverse affects associated with the intravenous administration of fluorescein dye. When viewed alongside corresponding structural B-scans, optical coherence tomography angiography demonstrates almost all of the clinical and fluorescein angiographic findings that are characteristic of acute and chronic retinal vein occlusion, such as a decrease in capillary perfusion, macular edema, vascular dilation, foveal avascular zone enlargement, and venous-venous collateral formation.

Intraocular Pressure Reduction Is Associated with Reduced Venous Pulsation Pressure

Purpose

To explore whether alterations in intraocular pressure (IOP) affect vein pulsation properties using ophthalmodynamometric measures of vein pulsation pressure.

Patients and Methods

Glaucoma patients had two retinal vein pulsation pressure (VPP) measurements from upper and lower hemiveins performed by ophthalmodynamometry at least 3 months apart. All subjects had VPP and IOP recorded at two visits, with standard automated perimetry, central corneal thickness (CCT) recorded at the initial visit. Where venous pulsation was spontaneous ophthalmodynamometry could not be performed and VPP was considered equal to IOP. Change in VPP was calculated and binarized with reduction in pressure scored 1 and no change or increase scored as 0. Data analysis used a mixed logistic regression model with change in VPP as response variable and change in IOP, visual field loss (mean deviation), CCT and time interval as explanatory variables.

Results

31 subjects (20 females) with mean age 60 years (sd 11) were examined with change in VPP being significantly associated with change in IOP (odds ratio 1.6/mmHg, 95% CI 1.2 to 2.1 in the glaucoma patients but not suspect patients (p = 0.0005).

Conclusion

Change in VPP is strongly associated with change in IOP such that a reduced intraocular pressure is associated with a subsequent reduction in VPP. This indicates that reduced IOP alters some retinal vein properties however the nature and time course of these changes is not known.

Pathogenesis of optic disc edema in raised intracranial pressure

Optic disc edema in raised intracranial pressure was first described in 1853. Ever since, there has been a plethora of controversial hypotheses to explain its pathogenesis. I have explored the subject comprehensively by doing basic, experimental and clinical studies. My objective was to investigate the fundamentals of the subject, to test the validity of the previous theories, and finally, based on all these studies, to find a logical explanation for the pathogenesis. My studies included the following issues pertinent to the pathogenesis of optic disc edema in raised intracranial pressure: the anatomy and blood supply of the optic nerve, the roles of the sheath of the optic nerve, of the centripetal flow of fluids along the optic nerve, of compression of the central retinal vein, and of acute intracranial hypertension and its associated effects. I found that, contrary to some previous claims, an acute rise of intracranial pressure was not quickly followed by production of optic disc edema. Then, in rhesus monkeys, I produced experimentally chronic intracranial hypertension by slowly increasing in size space-occupying lesions, in different parts of the brain. Those produced raised cerebrospinal fluid pressure (CSFP) and optic disc edema, identical to those seen in patients with elevated CSFP. Having achieved that, I investigated various aspects of optic disc edema by ophthalmoscopy, stereoscopic color fundus photography and fluorescein fundus angiography, and light microscopic, electron microscopic, horseradish peroxidase and axoplasmic transport studies, and evaluated the effect of opening the sheath of the optic nerve on the optic disc edema. This latter study showed that opening the sheath resulted in resolution of optic disc edema on the side of the sheath fenestration, in spite of high intracranial CSFP, proving that a rise of CSFP in the sheath was the essential pre-requisite for the development of optic disc edema. I also investigated optic disc edema with raised CSFP in patients, by evaluating optic disc and fundus changes by stereoscopic fundus photography and fluorescein fundus angiography. Based on the combined information from all the studies discussed above, it is clear that the pathogenesis of optic disc edema in raised intracranial pressure is a mechanical phenomenon. It is primarily due to a rise of CSFP in the optic nerve sheath, which produces axoplasmic flow stasis in the optic nerve fibers in the surface nerve fiber layer and prelaminar region of the optic nerve head. Axoplasmic flow stasis then results in swelling of the nerve fibers, and consequently of the optic disc. Swelling of the nerve fibers and of the optic disc secondarily compresses the fine, low-pressure venules in that region, resulting in venous stasis and fluid leakage; that leads to the accumulation of extracellular fluid. Contrary to the previous theories, the various vascular changes seen in optic disc edema are secondary and not primary. Thus, optic disc edema in raised CSFP is due to a combination of swollen nerve fibers and the accumulation of extracellular fluid. My studies also provided information about the pathogeneses of visual disturbances in raised intracranial pressure.

Blood flow velocity in monocular retinoblastoma assessed by color Doppler

OBJECTIVE

To analyze the flow of retrobulbar vessels in retinoblastoma by color Doppler imaging.

METHODS

A prospective study of monocular retinoblastoma treated by enucleation between 2010 and 2014. The examination comprised fundoscopy, magnetic resonance imaging, ultrasonography and color Doppler imaging. The peak blood velocities in the central retinal artery and central retinal vein of tumor-containing eyes (tuCRAv and tuCRVv, respectively) were assessed. The velocities were compared with those for normal eyes (nlCRAv and nlCRVv) and correlated with clinical and pathological findings. Tumor dimensions in the pathological sections were compared with those in magnetic resonance imaging and ultrasonography and were correlated with tuCRAv and tuCRVv. In tumor-containing eyes, the resistivity index in the central retinal artery and the pulse index in the central retinal vein were studied in relation to all variables.

RESULTS

Eighteen patients were included. Comparisons between tuCRAv and nlCRAv and between tuCRVv and nlCRVv revealed higher velocities in tumor-containing eyes (p < 0.001 for both), with a greater effect in the central retinal artery than in the central retinal vein (p = 0.024). Magnetic resonance imaging and ultrasonography measurements were as reliable as pathology assessments (p = 0.675 and p = 0.375, respectively). A positive relationship was found between tuCRAv and the tumor volume (p = 0.027). The pulse index in the central retinal vein was lower in male patients (p = 0.017) and in eyes with optic nerve invasion (p = 0.0088).

CONCLUSIONS

TuCRAv and tuCRVv are higher in tumor-containing eyes than in normal eyes. Magnetic resonance imaging and ultrasonography measurements are reliable. The tumor volume is correlated with a higher tuCRAv and a reduced pulse in the central retinal vein is correlated with male sex and optic nerve invasion.

Subinternal limiting lamina hemorrhages associated with sudden vascular pressure rise: yellow preretinal hemorrhages

A group of patients with subinternal limiting lamina hemorrhages associated with the Valsalva maneuver have been described. A majority of the patients have shown a striking yellowish coloration to the globular preretinal lesions during their evolution. This unique coloration is probably due to the accumulation of bilirubin during hemoglobin disintegration. Visual prognosis is usually excellent and no retinal or vascular abnormalities have been found after the hemorrhage disappears. The unusual fundus picture presented by this lesion may pose diagnostic problems if the patient is initially seen when this yellow mass is present.

RetinaCAD, a system for the assessment of retinal vascular changes

This paper introduces RetinaCAD, a system, for the fast, reliable and automatic measurement of the Central Retinal Arteriolar Equivalent (CRAE), the Central Retinal Venular Equivalent (CRVE), and the Arteriolar-to-Venular Ratio (AVR) values, as well as several geometrical features of the retinal vasculature. RetinaCAD identifies important landmarks in the retina, such as the blood vessels and optic disc, and performs artery/vein classification and vessel width measurement. The estimation of the CRAE, CRVE and AVR values on 480 images from 120 subjects has shown a significant correlation between right and left eyes and also between images of same eye acquired with different camera fields of view. AVR estimation in retinal images of 54 subjects showed the lowest values in people with diabetes or high blood pressure thus demonstrating the potential of the system as a CAD tool for early detection and follow-up of diabetes, hypertension or cardiovascular pathologies.

Lack of spontaneous venous pulsation: possible risk indicator in normal tension glaucoma?

PURPOSE

Recently, the absence of spontaneous venous pulsation (SVP) has been suggested as a vascular risk factor for primary open-angle glaucoma (POAG). As the mechanism behind this phenomenon is still unknown, the authors have studied this vascular component using colour Doppler imaging (CDI).

METHODS

A total of 236 patients were divided into three diagnostic groups: healthy controls (81), POAG (86) and normal tension glaucoma (NTG; 69). All subjects were submitted to CDI studies of the retrobulbar circulation, intraocular pressure measurements and assessment of SVP existence. Mann-Whitney, chi-square contingency tables and Spearman correlations were used to explore differences and correlations between variables in the diagnostic groups.

RESULTS

Eighty-two percent of healthy controls had SVP (66/81), while a smaller numbers were registered in both glaucoma groups: POAG - 50% (43/86); NTG - 51% (35/69). In NTG patients, but not in POAG patients, the prevalence of the SVP phenomenon decreases with increased glaucoma damage (p = 0.04; p = 0.55, respectively). Overall glaucoma patients from both groups had lower central retinal vein (CRV) velocities than the healthy controls (p < 0.05). NTG patients with SVP had less severe visual field defects (mean defect -6.92 versus -11.1, p < 0.05), higher [correction added after online publication 21 September 2012; the word 'higher' has been inserted to replace the word 'lower'] peak systolic and mean flow velocities in the central retinal artery (p < 0.01; p < 0.05, respectively) as well as higher [correction added after online publication 21 September 2012; the word higher has been inserted to replace the word lower] maximal velocities and RI of the CRV (p < 0.02; p < 0.05, respectively).

CONCLUSIONS

Glaucoma patients have a decrease in CRV velocities. SVP is less prevalent in glaucoma patients than in healthy individuals. This phenomenon apparently reflects different hemodynamic patterns in the central retinal vessels. This variable may be of particular importance in NTG patients, where it may be associated with more advanced functional damage.

Neurovascular dysfunction precedes neural dysfunction in the retina of patients with type 1 diabetes

PURPOSE

A variety of studies have shown that flicker-induced vasodilatation is reduced in patients with diabetes. It is, however, unclear whether reduced neural activity or abnormal neurovascular coupling is the reason for this phenomenon. In the present study, we hypothesized that retinal neurovascular dysfunction precedes neural dysfunction in patients with early type 1 diabetes.

METHODS

In the present study, 50 patients with type 1 diabetes without retinopathy and 50 healthy age- and sex-matched control subjects were included. The retinal vascular response to flicker stimulation was measured using the dynamic Retinal Vessel Analyzer. In addition, the response in retinal blood velocity to flicker stimulation as assessed with laser Doppler velocimetry was studied in a subgroup of patients. Pattern electroretinography (ERG) was used to measure neural retinal function.

RESULTS

The flicker responses of both retinal arteries and veins were significantly reduced in patients with diabetes (veins in the diabetic group: 3.5 ± 2.3% versus healthy control group: 4.6 ± 2.0%; P = 0.022 between groups, whereas arteries in the diabetic group: 2.0 ± 2.7% versus healthy control group: 3.8 ± 1.7%; P < 0.001 between groups). Likewise, the response of retinal blood velocity was reduced in patients with diabetes, although adequate readings could only be obtained in a subgroup of subjects (diabetic group [n = 22]: 19 ± 7%; healthy control group [n = 24]: 43 ± 19% P < 0.001 between groups). The parameters of pattern ERG were not different between the two groups.

CONCLUSIONS

The study confirms that flicker responses are reduced early in patients with type 1 diabetes. This is seen before alterations in pattern ERG indicating abnormal neurovascular coupling.

Vitamin D deficiency is not associated with changes in retinal geometric parameters in young people with type 1 diabetes

Changes in retinal geometric parameters predict risk and progression of diabetic retinopathy (DR). We have shown that vitamin D deficiency (VDD) is associated with DR. We hypothesized that VDD mediates changes in retinal geometric parameters. Retinal vascular geometric parameters were assessed using a semiautomated computer program in photographs from young people with type 1 diabetes (T1D) (n = 481) and summarized as central retinal arteriolar and venular equivalents (CRAE, CRVE), fractal dimension, length-diameter ratio, branching angle and curvature tortuosity. Parameters were compared between those with and without DR and VDD (25-hydroxyvitamin D concentration ≤ 50 nmol/L). Retinal vascular geometric parameters were also compared across quartiles of vitamin D levels. Median CRVE was higher in patients with DR compared with those without (median (IQR) CRVE 247.3  μ m (31.3) versus 238.8  μ m (23.5), P = 0.01). Fractal dimension was marginally greater in patients without VDD (1.49 (0.06) versus 1.47 (0.07) P = 0.03). There was no difference in CRAE, CRVE, length-diameter ratio, branching angle, and curvature tortuosity between those with and without VDD and across quartiles of 25OHD. In conclusion, DR is associated with higher CRVE in young people with T1D; however, VDD is not associated with changes in retinal vascular geometric measures, suggesting an earlier role in the time course of DR pathogenesis.

Dynamics of retinal vessel response to flicker light in glaucoma patients and ocular hypertensives

PURPOSE

To analyze dynamics of retinal vessel dilation response to flicker light in patients with glaucoma and ocular hypertension.

PATIENTS AND METHODS

Response to flicker light was measured in retinal vessels by means of Retinal Vessel Analyzer. After the baseline 50 seconds long diameter recording of inferior and superior temporal artery and vein, three flicker stimulations of 20 seconds duration was applied, with a 80 seconds break in between. Area under the curve of the vessel diameter (AUC) was compared during 3 flicker periods in the open angle glaucoma patients group (POAG, n = 47) and ocular hypertensives (OHT, n = 46) and age-matched healthy controls (n = 56)

RESULTS

POAG eyes demonstrated smaller response of all vessels to flicker light in general than the other two groups (p = 0.0008), but the response dynamics was significantly different between the groups (p = 0.038), showing in three flicker periods a delayed increasing response in the POAG and OHT groups, and remaining stable in healthy subjects.

CONCLUSION

General vessel response to flicker light was decreased in POAG patients despite the slow improvement in repeated flicker stimulation, indicating an altered response pattern.

Oxygen saturation in central retinal vein occlusion

PURPOSE

To test whether oxygen saturation is affected in retinal blood vessels in patients with central retinal vein occlusion (CRVO).

DESIGN

Prospective observational case series.

METHODS

Oxygen saturation of hemoglobin was measured in retinal blood vessels in 10 patients with unilateral CRVO. The duration of CRVO before measurement was from 1 day to about 6 months. Two patients were excluded because of poor quality of oximetry images. The spectrophotometric retinal oximeter is based on a fundus camera. It simultaneously captures images of the retina at 605 nm and 586 nm and calculates optical density (absorbance) of retinal vessels at both wavelengths. The ratio of the 2 optical densities is approximately linearly related to hemoglobin oxygen saturation. Mean oxygen saturation was calculated for first- and second-degree arterioles and venules in both eyes of each patient.

RESULTS

The mean oxygen saturation of hemoglobin in retinal venules was 49% ± 12% (mean ± SD, n = 8) in eyes affected by CRVO and 65% ± 6% in unaffected fellow eyes (P = .003). The mean arteriolar oxygen saturation was 99% ± 3% in CRVO eyes and 99% ± 6% in the fellow eyes. Venular oxygen saturation was variable within and between CRVO eyes.

CONCLUSIONS

Oxygen saturation in retinal venules is lower in eyes with CRVO than in fellow eyes and there is considerable variability within and between CRVO eyes. Arteriolar saturation is the same in CRVO and fellow eyes. Retinal oxygenation is disturbed in CRVO.

Effects of intravitreal bevacizumab (Avastin) therapy on retrobulbar blood flow parameters in patients with neovascular age-related macular degeneration

BACKGROUND

To investigate the effects of intravitreal bevacizumab on retrobulbar circulation in patients with neovascular age-related macular degeneration (AMD).

METHOD

Thirty patients with neovascular age-related macular degeneration were assessed prospectively by both color Doppler imaging and fundus fluorescein angiography. Spectral Doppler analysis allowed the measurement of the maximum velocity (Vmax) and minimum velocity (Vmin) of the central retinal vein (CRV), and peak systolic (PSV), end-diastolic (EDV) velocities of blood flows, and pulsatility index (PI) and resistance index (RI) values in the central retinal artery (CRA), nasal and temporal posterior ciliary arteries (NPCA, TPCA), and ophthalmic artery (OA). The t test for paired samples was used to compare retrobulbar blood flow values before and after intravitreal bevacizumab injection.

RESULT

PSV and EDV of the NPCA and PSV of the TPCA were significantly decreased after intravitreal bevacizumab injection (p < 0.05). There was no statistically significant difference in the other parameters.

CONCLUSION

Our results suggest that intravitreal bevacizumab therapy has a measurable effect on retrobulbar blood flow.

The associations between blood levels of homocysteine, folate, vitamin B12, and retinal vascular caliber

PURPOSE

To assess the association of total serum levels of homocysteine (tHcy), folate, and vitamin B12 with retinal vascular caliber in older adults.

DESIGN

Cross-sectional, population-based study.

METHODS

One thousand seven hundred and seventy-two of 2334 Blue Mountains Eye Study participants examined had fundus photographs taken and retinal arteriolar and venular caliber measured using computer-assisted techniques and summarized. Serum folate and vitamin B12 levels and tHcy were determined from venous blood samples. Linear regression models adjusting for age, gender, mean arterial blood pressure, smoking, and diabetes were used to assess whether serum levels of tHcy, folate, and vitamin B12 were associated with retinal arteriolar and venular caliber.

RESULTS

Arteriolar and venular caliber was not associated with tHcy in the total population. Further analysis demonstrated a significant serum homocysteine-gender interaction (P = .04). A significant inverse association between tHcy and arteriolar caliber was found in men only (P = .03), with a threshold detected at a level of 17 micromol/l. Above this threshold, increasing tHcy was linearly associated with narrower arteriolar caliber (0.86 microm reduction per 1.0 micromol/l increase in tHcy) in men, but no significant association was found below this threshold. No significant associations were observed between serum folate or vitamin B12 levels and either retinal vessel caliber.

CONCLUSIONS

Retinal vascular caliber is associated with tHcy in men but not women. This finding may reflect the stronger association between blood pressure and tHcy in men than in women.

Retinal vessel response to flicker light in children and adolescents with type 1 diabetes mellitus and overweight or obesity

It was the goal of the trial to assess cardiovascular risk factors in children and adolescents with type 1 diabetes mellitus or overweight/obesity. All children and adolescents (n=77 [n=45 patients with diabetes mellitus, n=32 patients with overweight/obesity]) admitted to our hospital during the period from 01/07 to 31/08/2006 were included in the trial. Socio-demographic and laboratory data (age, sex, diabetes duration, BMI, BMI-SDS, HbA1c, fasting blood glucose, oGTT in patients with overweight/obesity, lipids, CRP, TSH, creatinine, and microalbuminuria) were assessed. The diameter of a retinal arterial and a venous segment was measured continuously on-line with a Dynamic Vessel Analyzer, carotid intima-media thickness (IMT) was measured, and 24-h-blood pressure monitoring was applied.

RESULTS

Flicker light stimulation induces a comparable arterial dilatation in patients with type 1 diabetes and overweight/obesity. Univariate ANOVA in patients with type 1 diabetes shows an influence of diastolic blood pressure on arterial dilatation. Other factors such as BMI, age, diabetes duration, smoking, sex, HbA1c and insulin dose/kg had no effect.

CONCLUSIONS

In children and adolescents with diabetes or overweight/obesity retinal vascular alterations seem to be more sensitive and already present before the occurrence of classic cardiovascular markers.

Doppler ultrasonography imaging of hemodynamic alteration of retrobulbar circulation in type 1 diabetic children and adolescents without retinopathy

AIM

We aimed to investigate the retrobulbar blood circulation using Colour Doppler Imaging (CDI) in type 1 diabetic children and adolescents who had no diabetic retinopathy and to compare the results with their healthy peers.

METHODS

Forty-nine patients with type 1 diabetes mellitus with no retinopathy on fundoscopic examination were included in the study. Forty-nine healthy children were defined as the control group. Central retinal artery (CRA), ophthalmic artery (OA) and posterior ciliary artery (PCA) were examined with Doppler US bilaterally. Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive indices (RI) for each artery were recorded.

RESULTS

Blood flow velocity of the OA was significantly different in diabetic patients (p<0.05). EDV of the OA was significantly higher (p=0.011) and RI was significantly lower (p=0.027) in patients with diabetes duration of longer than 5 years. RI of the CRA was significantly higher in patients who had higher microalbuminuria levels (p=0.016).

CONCLUSION

EDV of the OA increases and RI of the OA decreases in diabetes duration longer 5 years. Raised AER increases RI of the CRA. These findings may be the initial changes in the arterial circulation before vascular rigidity develops.

Assessment of the spontaneous pulsations of the central retinal vein in daily ophthalmic practice

The purpose of this study is to assess the frequency of eyes with a spontaneous pulsation of the central retinal vein in the setting of a busy daily ophthalmic practice. The clinical observational case-series study included 690 eyes (345 subjects). The optic disc was ophthalmoscopically assessed using a non-contact ophthalmoscopic lens at the slit lamp. Out of the study population, 526 eyes (76.2%) of 265 (76.8%) subjects showed a detected spontaneous pulsation of the central retinal vein (prevalence rate: 76.2 +/- 1.6% [mean +/- standard error] per eye, and 76.8 +/- 2.3% per subject). In univariate analysis, the presence of a detected spontaneous central retinal vein pulsations was statistically associated with systolic systemic blood pressure (P = 0.04) and with the ocular perfusion pressure (P = 0.03). The results suggest that as examined in the setting of a busy daily ophthalmic practice, the central retinal vein was found to show a spontaneous pulsation in about 80% of the subjects.

Biomechanical Assessment of Radial Optic Neurotomy

PURPOSE

A biomechanical model was constructed to simulate the potential therapeutic effect that the surgical procedure radial optic neurotomy (RON) would have on an eye with a central retinal vein occlusion.

DESIGN

Experimental study.

CONTROLS

Model eyes undergoing RON were compared to control eyes under the same baseline conditions.

INTERVENTION

Radial optic neurotomy. We modeled the optic nerve, lamina cribrosa, and the sclera separately and then reassembled the components. Material properties of the sclera and lamina cribrosa were extracted from the literature and both stiff and more elastic values were used for the optic nerve. Intraocular and arterial pressures were varied across a wide range in the analysis.

MAIN OUTCOME MEASURE

Change in central retinal vein lumen size.

RESULTS

Over a clinically relevant range of boundary conditions, the increase in the lumen area of the central retinal vein lumen after RON remained trivial, ranging from 1% to a maximum of 5%.

CONCLUSIONS

The biomechanical effect of RON is negligible, and is unlikely to be a procedure that could mechanically ameliorate the clinical sequelae of a central vein occlusion.

The relationship of retinal vascular calibre to diabetes and retinopathy: the Australian Diabetes, Obesity and Lifestyle (AusDiab) study

AIMS/HYPOTHESIS

The aim of the study was to examine the relationship of retinal vascular calibre with glucose intolerance, diabetes and retinopathy in a population-based cohort.

METHODS

The Australian Diabetes, Obesity and Lifestyle study recruited adults aged > or =25 years old from across Australia. Participants were classified using an oral glucose tolerance test as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT), impaired fasting glucose (IFG), known diabetes or newly diagnosed diabetes. Digital retinal photographs were taken of all participants with diabetes, IGT and IFG, and a sample of those with NGT, and graded for the presence of retinopathy. Retinal vascular calibre was measured from photographs by a computer-assisted method.

RESULTS

Of the 1,998 participants with gradable retinal images, 16% had known diabetes, 17% newly diagnosed diabetes, 42% IGT, 6% IFG and 19% NGT. After multivariable adjustment, retinal arteriolar calibre was significantly larger in people with known diabetes (178.9 microm) compared with participants with NGT (174.6 microm, p = 0.02), IGT/IFG (175.5 microm, p = 0.02) or newly diagnosed diabetes (175.6 microm, p = 0.047). One SD increase in mean arteriolar calibre was associated with higher odds of diabetes compared with NGT (odds ratio [OR] = 1.28, 95%CI = 1.06-1.55). After multivariable adjustment, each SD increase in venular calibre was associated with higher odds of having retinopathy in persons with IGT/IFG (OR = 1.78, 95%CI = 1.36-2.34) or in persons with diabetes (OR = 1.68, 95%CI = 1.23-2.29).

CONCLUSIONS/INTERPRETATION

Diabetes is associated with larger retinal arteriolar calibre and retinopathy with larger retinal venular calibre. The contrasting associations may reflect different underlying pathophysiological processes in the natural history of diabetes.

Functional and anatomical investigations in racemose haemangioma

PURPOSE

To determine the vascular morphology of racemose haemangioma and related functional alterations in arteriovenous (AV) malformation type 3.

METHODS

A 17-year-old patient with unilateral racemose haemangioma received a full ophthalmic examination including Snellen visual acuity (VA) and Goldmann visual field. The central vision was investigated by scanning laser ophthalmoscope (SLO) and multifocal electroretinogram (mfERG). The ocular haemodynamics were examined by fluorescence angiography and Doppler ultrasound. The tomographic contour of the vascular architecture was visualized using B-scan ultrasound, Stratus optical coherence tomography (OCT) and three-dimensional Heidelberg retina tomograph (3D-HRT II).

RESULTS

The VA of the patient's right eye was reduced to 20/400 and her visual field was constricted concentrically. Microperimetry revealed a small central field with good central fixation. The mfERG demonstrated reduced amplitudes of the central retina. On fluorescein angiography, there was a fast filling of the retinal branches related to the racemose vessels. Doppler ultrasound confirmed a significantly changed haemodynamic flow in the racemose vessels. Ultrasound, OCT and HRT demonstrated a prominent optic nerve head.

CONCLUSION

The racemose haemangioma led to a marked visual field defect. Racemose haemangiomas are associated with severe changes in the haemodynamics of the retinal vasculature.

Diagnostic accuracy of retinal abnormalities in predicting disease activity in MS

OBJECTIVES

To assess the association between the thickness of the retinal nerve fiber layer (RNFL), assessed by optical coherence tomography (OCT), retinal periphlebitis (RP), and multiple sclerosis (MS) disease activity.

METHODS

We studied a prospective cohort of 61 patients and 29 matched controls for 2 years, performing a neurologic assessment every 3 months and an ophthalmologic evaluation, including OCT scans, every 6 months. Baseline MRI studies were also carried out from which brain volume and lesion load were assessed.

RESULTS

We found that the RNFL thickness in patients with MS was thinner than in controls, particularly in the temporal quadrant (p = 0.004). Although RNFL atrophy was greater in patients who also had optic neuritis (p = 0.002), it also augmented in MS patients who did not have optic neuritis compared with controls (p = 0.014). RNFL atrophy was correlated with greater disability (r = -0.348, p = 0.001) and longer disease duration (r = -0.301, p = 0.003). Furthermore, baseline temporal quadrant RNFL atrophy was associated with the presence of new relapses and changes in the Expanded Disability Status Scale by the end of the study (p < 0.05 in all cases). Indeed, RNFL thickness was correlated with white matter volume (r = 0.291, p = 0.005) and gray matter volume (r = 0.239, p = 0.021). The presence of RP was a risk factor for having new relapses in the next 2 years (odds ratio = 1.52, p = 0.02), and patients with RP had larger gadolinium-enhancing lesions volume (p = 0.003).

CONCLUSION

Retinal nerve fiber layer atrophy and the presence of retinal periphlebitis are associated with disease activity, suggesting that retinal evaluation can be used as biomarkers of multiple sclerosis activity.

Long-term effects of radial optic neurotomy for central retinal vein occlusion consecutive interventional case series

PURPOSE

To investigate the long-term (minimum 24 months follow-up) clinical results of radial optic neurotomy (RON) following a pars plana vitrectomy (PPV) with internal limiting membrane peeling as treatment for central retinal vein occlusion (CRVO).

METHODS

Interventional case series of 14 consecutive patients (14 eyes) with CRVO who were treated with a PPV combined with RON within 1 year of diagnosis.

RESULTS

Median baseline visual acuity (VA) was 1.05 logMAR (approximately 0.09 Snellen) in the affected eye. The follow-up period ranged from 24 to 48 months postoperatively, median 30 months. At the 24-month follow-up examination, median VA was 1.005 logMAR in the affected eye-a significant improvement (p = 0.013). Six patients (43%) gained 1 or more lines of VA (mean VA gain = 1.7 lines), while the VA of four patients (29%) improved by 3 or more lines. The eyes with nonischemic CRVO demonstrated a significantly higher improvement in VA (p = 0.0007) than the eyes with ischemic CRVO.

CONCLUSION

With RON clinically relevant improvements on a long-term basis seem achievable. Patients with nonischemic CRVO may respond more favorably than patients with ischemic CRVO.

Retinal vein pulsation predicts increasing optic disc excavation

Spontaneous retinal vein pulsation in glaucoma

Altered Retrobulbar Hemodynamics in Patients Who Have Transient Monocular Blindness Without Carotid Stenosis

Background and Purpose— This study was to evaluate the retrobulbar hemodynamics in patients who have transient monocular blindness (TMB) without carotid stenosis.

Methods— Fifty-nine patients who have TMB without carotid stenosis were studied along with 59 age- and sex-matched controls. Color Doppler–imaging was used to study the retrobulbar hemodynamic by measuring the flow velocities (peak-systolic velocity, and end-diastolic velocity), vascular resistance indices (pulsatility index, and resistance index) in central retinal arteries, short posterior ciliary arteries, and ophthalmic arteries. The patients were divided into 2 groups according to the attack frequency: group 1 (occasional TMB, 2 or fewer attacks, 26 patients) and group 2 (frequent TMB, 3 or more attacks, 33 patients).

Results— The risk factors for atherosclerosis were similar between the cases and controls. The means of end-diastolic velocity were significantly lower in central retinal arteries and ophthalmic arteries, and the pulsatility index and resistance index were significantly higher in all the 3 retrobulbar vessels in TMB patients than for the controls. The differences between patients and controls were greater for the group-2 patients.

Conclusion— Patients who have TMB without carotid stenosis had altered retrobulbar hemodynamics with a generalized increase in vascular resistance in the retrobulbar arteries. The role of venous hypertension as an etiology needs further study.

Central retinal artery and vein collapse pressure in giant cell arteritis versus nonarteritic anterior ischaemic optic neuropathy

Arteritic anterior ischaemic optic neuropathy and nonarteritic anterior ischaemic optic neuropathy are acute optic neuropathies, which have to be differentiated from each other. It was the purpose of this study to assess whether ophthalmodynamometry with an assessment of the collapse pressure of the central retinal artery (CRA) and vein (CRV) is helpful for that. Using a Goldmann contact lens-associated ophthalmodynamometer, the diastolic collapse pressure of the CRA and CRV were measured in six patients (eight eyes) with giant cell arteritis-induced anterior ischaemic optic neuropathy (GC-AION) and in 10 patients (12 eyes) with acute non-arteritic anterior ischaemic optic neuropathy (NAION). CRA collapse pressure was significantly (P=0.001; 95% confidence interval (CI): -68.7, -20.0) lower in the GC-AION group (52.7+/-24.6 arbitrary units) than in the NAION group (97.0+/-25.8 arbitrary units). CRV collapse pressure did not vary significantly (P=0.47). As measured by ophthalmodynamometry, CRA pressure is significantly lower in GC-AION than in NAION. CRV pressure does not vary markedly. These finding may be helpful for the clinical differentiation between GC-AION and NAION, and may give hints for the pathogenesis.

Orbital color Doppler imaging in Behçet's disease with or without ocular involvement

PURPOSE

To investigate the value of color Doppler imaging (CDI) of orbital vasculature in the assessment of ocular involvement in patients with Behçet's disease (BD) without clinical ophthalmologic abnormalities.

METHODS

CDI of the orbital vessels were performed on 26 eyes of 13 patients who were diagnosed as having BD with ocular involvement (group 1), 65 eyes of 33 patients who had BD without ocular involvement (group 2) and 40 eyes of 20 healthy volunteers (group 3). Peak systolic (PSV) and end-diastolic (EDV) blood flow velocities and resistivity index (RI) measurements were obtained for the ophthalmic artery (OA) and central retinal artery (CRA). The mean velocity of the central retinal vein (CRV) was also measured.

RESULTS

For the OA, PSV and EDVs were significantly lower and RIs were significantly higher in group 2 than in control subjects. In group 1, only the EDVs of OA were significantly lower than in healthy subjects. For the CRA, PSV and EDVs were significantly lower, and RIs were significantly higher in both BD groups than those in group 3. When group 1 and group 2 were compared, the differences between PSV, EDV and RI measurements for the CRA and OA were statistically insignificant. There was no significant difference in blood flow velocity of the CRV between the three groups.

CONCLUSION

Major hemodynamic changes were observed in the ophthalmic vasculature of Behçet's patients with or without ocular involvement by CDI. CDI may detect ocular blood flow alterations before initial clinical manifestations.

[Transient increased retinal hemorrhage and the retinal venous blood flow change in the course of non-ischemic central retinal vein occlusion treated with an anticoagulant]

PURPOSE

To investigate transient increased retinal hemorrhage during anticoagulant therapy and changes in the retinal venous blood flow in the course of non-ischemic central retinal vein occlusion (CRVO).

METHODS

Seventeen patients(eighteen eyes) with non-ischemic CRVO were studied. The retinal vein diameter, blood velocity, and blood flow were determined by the laser Doppler method in seven patients.

RESULTS

The retinal hemorrhage increased in nine eyes (50%); however, the retinal hemorrhage was transient and it finally decreased without vision loss in seven of the eyes. The retinal hemorrhage increased in the other two eyes and they became ischemic. The vessel diameter decreased and both velocity and blood flow increased in six of the seven patients two weeks after the treatment. There was no significant change in blood flow in cases which showed a transient increase in retinal hemorrhage, and they did not show a decrease in vision; however, only one eye which became ischemic showed a decrease in blood flow.

CONCLUSION

We can judge whether an increase in retinal hemorrhage is transient or the clinical condition is getting worse in an early stage by measuring the retinal vein blood flow quantitatively by laser Doppler flowmetry.

MRI findings in isolated spontaneous thrombosis of the superior ophthalmic vein

We report the case of a 40-year-old woman with systemic lupus erythematosus who presented with spontaneous thrombosis of the superior ophthalmic vein resulting in permanent vision loss. The diagnosis was established by noncontrast CT scanning, gadolinium-enhanced MRI, and conventional catheter angiography.

Correlation between higher blood flow velocity in the central retinal vein than in the central retinal artery and severity of nonproliferative diabetic retinopathy

PURPOSE

To assess the correlation between a higher blood flow velocity in the central retinal vein (CRV) than in the central retinal artery (CRA) and the severity of nonproliferative diabetic retinopathy (non-PDR).

METHODS

We evaluated both eyes of 20 non-PDR patients with higher peak systolic velocity (PSV) in the CRV than in the CRA unilaterally as determined by color Doppler imaging (CDI). The eyes with higher PSV in the CRV were placed in group D2-H, and the fellow eyes were placed in group D2-L. The stage of non-PDR was determined by the guidelines of the Early Treatment Diabetic Retinopathy Study. Normal subjects and non-PDR patients without higher PSV in the CRV were evaluated as CDI controls.

RESULTS

Advanced non-PDR (P=0.001) and cystoid macular edema (P=0.02) were statistically more frequent in group D2-H. The velocities in the ophthalmic artery and the short posterior ciliary artery were not statistically different among all groups. The velocities in the CRA were similar in all non-PDR groups and significantly lower than in the normal subjects (P<0.05). The velocities in the CRV were significantly higher only in group D2-H (P<0.001).

CONCLUSION

Higher PSV in the CRV than in the CRA was significantly correlated with the severity of non-PDR, especially in the presence of cystoid macular edema.

[Pathogenesis and treatment of myopic foveoschisis]

Myopic foveoschisis (MF) can now be recognized as the result of recent progress in imaging diagnostic technology such as optical coherence tomography (OCT). MF predominantly occurs in highly myopic eyes with posterior staphyloma, and often induces visual loss and/or metamorphopsia. In order to better understand the detailed pathogenesis of MF, we observed 21 myopic eyes after vitrectomy using OCT. Retinal microfolds along the retinal vessels were observed in over 60% of the patients 6 months after surgery. Relative inflexibility of retinal arterioles/venules may be one of the causes for MF. We performed a pilot study (6 eyes of 5 patients) to treat MF by vitrectomy including vitreous cortex removal, internal limiting membrane peeling, and gas tamponade. In all 6 eyes the fovea was reattached and vision improved by more than two lines. This pilot study indicates that vitrectomy is an effective and safe treatment for MF.

Value of retinal vein pulsation characteristics in predicting increased optic disc excavation

BACKGROUND

Retinal vein pulsation is often absent in glaucoma, but can be induced by applying a graded ophthalmodynamometric force (ODF) to the eye, which is elevated in glaucoma.

AIM

To assess whether ODF has a predictive value in determining glaucoma progression.

METHODS

75 patients with glaucoma and suspected glaucoma were examined prospectively in 1996, and then re-examined at a mean of 82 months later. All subjects had intraocular pressure, visual fields, stereo optic disc photography and ODF measured on their initial visit. When venous pulsation was spontaneous, the ODF was said to be 0 g. At re-examination, central corneal thickness and blood pressure were also measured. Initial and subsequent optic disc photographs were compared and graded into those that had increased excavation and those that had remained stable. The relationship between increased excavation (recorded as a binary response) and the measured variables was modelled using a multiple mixed effects logistic regression.

RESULTS

ODF at the initial visit was strongly predictive of increased excavation (p = 0.004, odds ratio 1.16/g, range 0-60 g), with greater predictive value in women than in men (p = 0.004). Visual field mean deviation was predictive of increased excavation (p = 0.044), as was optic nerve haemorrhage in association with older age (p = 0.038). Central corneal thickness was not significantly predictive of increased excavation (p = 0.074) after having adjusted for other variables.

CONCLUSION

ODF measurement seems to be strongly predictive of the patient's risk for increased optic disc excavation. This suggests that ODF measurement may have predictive value in assessing the likelihood of glaucoma progression.

A "throttle" mechanism in the central retinal vein in the region of the lamina cribrosa

AIMS

To demonstrate a constriction in the central retinal vein in the region of the lamina cribrosa.

METHODS

A prospective comparative interventional study of 13 controls and 19 patients with central retinal vein occlusion (CRVO) using colour Doppler imaging of the central retinal artery and vein in the region of the lamina cribrosa and optic nerve posterior to the globe.

RESULTS

In controls peak velocities in the vein were higher in the region of the lamina cribrosa than the optic nerve, mean 175 mm/second (mm/s) and 49 mm/s respectively, p<0.0001. The velocities in the artery were also higher in the region of the lamina cribrosa, mean 122 mm/s and 92 mm/s, p = 0.007. The variability of the velocities in the region of the lamina cribrosa was 7.4% in the artery and 15.2% in the vein. The mean ratio of the velocities in the vein (4.2 (SD 2.1)) was significantly higher than the mean ratio in the artery (1.4 (SD 0.4), p<0.0001). In CRVO, the mean ratio in the vein was lower in the affected eyes (2.2 (SD 1.9), p<0.01) and fellow unaffected eyes (2.2 (SD 1.0), p = 0.003) than controls. The values were stable in eight after radial optic neurotomy.

CONCLUSION

The presence of a constriction of the vein in the region of the lamina cribrosa can be inferred from the presence of higher blood velocities at this site than further back in the optic nerve. In CRVO there may be a more uniform narrowing of the vein along its course in the nerve. Neurotomy did not affect the measurements.

Return of vision after transarterial coiling of a carotid cavernous sinus fistula: case report

BACKGROUND

Carotid cavernous sinus fistulae are abnormal communications between the carotid circulation and cavernous sinus that may arise spontaneously or develop after craniocerebral trauma. They may present with a constellation of signs and symptoms characteristic of raised cavernous sinus pressure, including orbital or retro-orbital pain, pulsatile proptosis, chemosis, ocular or cranial bruit, deterioration of visual acuity, or ophthalmoplegia. Visual loss is likely the result of multiple insults to the visual system, including reversal of venous drainage from the fistula, arterial flow into the superior ophthalmic vein, increased intraocular venous pressure, venous stasis retinopathy, and eventually ischemic optic neuropathy [Brodsky MC, Hoyt WF, Halbach VV, et al. Recovery from total monocular blindness after balloon embolization of carotid-cavernous fistula. Am J Ophthalmol 1987;104:86-87; Sanders MD, Hoyt WF. Hypoxic ocular sequelae of carotid-cavernous fistulae: study of the causes of visual failure before and after neurosurgical treatment in a series of 25 cases. Br J Ophthalmol 1969;53:82-97].

CASE DESCRIPTION

With few exceptions, the literature is replete with evidence of persistent blindness despite successful treatment of the CCF [Albuquerque FC, Heinz GW, McDougall CG. Reversal of blindness after transvenous embolization of a carotid-cavernous fistula: case report. Neurosurgery 2003;52:233-237; Brodsky MC, Hoyt WF, Halbach VV, et al. Recovery from total monocular blindness after balloon embolization of carotid-cavernous fistula. Am J Ophthalmol 1987;104:86-87; Weinstein JM, Rufenacht DA, Partington CR, et al. Delayed visual loss due to trauma of the internal carotid artery. Arch Neurol. 1991;48:490-497]. Here, we report a patient who experienced recovery of vision after endovascular obliteration of the offending CCF.

DISCUSSION

To our knowledge, this is the second reported case of recovery of visual function in a patient presenting with loss of light perception after treatment of a direct CCF.

Retrobulbar haemodynamics and morphometric optic disc analysis in primary open-angle glaucoma

BACKGROUND

Previous studies confirmed reduced retrobulbar haemodynamics in primary open-angle glaucoma (POAG).

AIM

To investigate a correlation between retrobulbar haemodynamics and morphometric neuroretinal rim analysis in patients with POAG.

METHODS

51 patients with POAG (mean (standard deviation (SD)) age 65 (11) years) were included in this clinical study. Blood flow velocities (peak systolic velocity (PSV) and end-diastolic velocity (EDV)) of the ophthalmic artery, central retinal artery (CRA), posterior ciliary arteries (PCA) and central retinal vein were measured using colour Doppler imaging (Siemens Sonoline Sienna, Erlangen, Germany). Optic disc morphometry was carried out using scanning laser tomography (Heidelberg Retinal Tomograph II Heidelberg Egineering Heidelberg, Germany). The stereometric parameters of the neuroretinal rim (rim area, rim volume, cup shape measure and retinal nerve fibre layer (RNFL) cross-sectional area) were used for analysis.

RESULTS

The PSV of the CRA was significantly (p<0.001) correlated with rim area (r = 0.50) and rim volume (r = 0.51). The minimum velocities of the central retinal vein were significantly (p<0.001) correlated with rim volume (r = 0.56) and RNFL cross-sectional area (r = 0.49). No correlations were found for the flow velocities of the ophthalmic artery and PCAs.

CONCLUSION

Retrobulbar haemodynamics of the central retinal artery and vein are correlated with the neuroretinal rim damage in POAG.

Regression of Alterations in Retinal Microcirculation Following Treatment for Arterial Hypertension

Evaluation of early hypertension-related alterations in retinal microcirculation has been subjective and poorly reproducible. The authors recently described a semiautomatic computerized system for evaluation of the calibre of retinal blood vessels that has shown very good reproducibility. In the study, this system was used to measure the calibres of retinal arterioles and veins, and their ratio, in a group of 51 hypertensive outpatients before and after 6 months of treatment with losartan or, if required for satisfactory blood pressure control, losartan plus hydrochlorothiazide. Mean retinal arteriole diameter increased from 0.0842 +/- 0.003 mm to 0.0847 +/- 0.003 mm (p = 0.001). Arteriovenous ratio increased from 0.753 +/- 0.03 to 0.756 +/- 0.03 (p = 0.005). This observation suggests regression of early hypertension-related alterations in retinal microcirculation after 6 months of antihypertensive treatment.

Early increase of retinal arterial and venous blood flow velocities at color Doppler imaging in brittle type 1 diabetes after islet transplant alone

Little information is currently available about the role of islet transplantation alone (ITA) on the retinal microcirculation. Our purpose was to investigate with color-Doppler-imaging the effect of ITA after one year on the blood flow velocities of central retinal artery and vein. Central retinal arteries and veins of both eyes of 10 ITA patients were evaluated with color-Doppler-imaging before and one year after transplant. Peak systolic velocity (psv), end diastolic velocity (edv) for arteries and maximum velocity (maxv), minimum velocity (minv) for veins were recorded and compared with a control group of type 1 diabetic patients. At one year, a statistically significant increase of blood flow velocities of central retinal arteries (psv: 6.09+/-0.46 vs. 10.12+/-1.20 cm/s, P=0.01) and veins (maxv: 3.12+/-0.28 vs. 6.12+/-1.00 cm/s, P=0.01) was found only in the ITA patients. An early, significant increase of arterial and venous retinal blood flow velocities was found after ITA.