Retrobulbar hemodynamic parameters in pseudoexfoliation syndrome and pseudoexfoliative glaucoma

Retinal nerve fiber layer and ophthalmic artery blood flow parameters in pseudoexfoliation syndrome and pseudoexfoliative glaucoma

OBJECTIVES

To investigate the relationship between ophthalmic artery (OA) blood flow parameters and retinal nerve fiber layer (RNFL) thickness in eyes with pseudoexfoliation (PEX).

METHODS

We compared PEX eyes without glaucoma (group A, n=53) and those with glaucoma (group B, n=18) with control eyes (group C, n=44). Subsequently, eyes in groups A and B were compared. Finally, OA color Doppler imaging measurements were recorded, and peripapillary RNFL analysis was performed.

RESULTS

The total RNFL measurements differed significantly among the groups (P=0.012), being thicker in group C than in group A (P=0.010) and significantly different between group B and groups A and C (both P=0.001). The peak systolic velocity (PSV) and end diastolic velocity (EDV) measurements of groups A and B were lower than those of group C (PSV: P=0.001 and P=0.001, respectively; EDV: P=0.001 and P=0.001, respectively). No significant difference was noted in resistive index (RI) measurements (P=0.370). In group B, significant negative correlations were noted between total RNFL and PSV (r=-0.743; P=0.001) and between total RNFL and EDV (r=-0.691; P=0.001), but not between total RNFL and RI measurements (P=0.548).

CONCLUSIONS

Pseudoexfoliation syndrome (PXS) with or without glaucoma was associated with a decrease in the PSV and EDV values of the OA. An extensive study may be needed to further explore the role of PXS in OA blood flow parameters. Total RNFL thickness values were lower in eyes with PEX than in those without.

The Role of Color Doppler Imaging in the Diagnosis of Glaucoma: A Review of the Literature

Glaucoma is a progressive optic neuropathy and one of the leading causes of irreversible blindness worldwide. Elevated intraocular pressure (IOP) is the major risk factor for the onset and progression of glaucoma. In addition to elevated IOP, impaired intraocular blood flow is also considered to be involved in the pathogenesis of glaucoma. Various techniques have been used to assess ocular blood flow (OBF), including Color Doppler Imaging (CDI), a technique used in ophthalmology in recent decades. This article reviews the role of CDI in both the diagnosis and effective monitoring of glaucoma progression, presenting the protocol for imaging and its advantages, as well as the limitations of its use. Moreover, it analyzes the pathophysiology of glaucoma, focusing on vascular theory and its role in the onset and progression of the disease.

Evaluation of the Effect of Duration on Retinal Nerve Fiber Layer Thickness and Choroidal Thickness in Exfoliation Syndrome and Exfoliative Glaucoma

Aims: To compare retinal nerve fiber layer (RNFL) thickness and choroidal thickness in patients with exfoliation syndrome (XFS) and exfoliative glaucoma (XFG) for 1−5 years or 6−10 years compared to healthy volunteers. Methods and Material: Seventy-eight eyes of 78 patients with XFG, 78 eyes of 78 patients with XFS, and 83 eyes of 83 healthy individuals were included in this prospective study. SD-OCT data for choroid thickness and RNFL were recorded. Results: RNFL thickness was statistically significantly lower in eyes with XFG and XFS than in the control group (p < 0.001). Macular choroidal thickness decreased significantly in the XFG group compared to the XFS and control groups (p < 0.001). No significant difference was observed between the XFS and control groups (p > 0.05). In terms of choroidal and RNFL thicknesses by years in XFG and XFS patients, values were lower in the patients diagnosed 6−10 years previously than in those diagnosed 1−5 years previously. However, the difference was not statistically significant (p > 0.05). Conclusions: Thinning of both choroidal and RNLF thickness in XFG and XFS patients may mean that PEX material is an important risk factor for the progression of XFS to XFG. In addition, thinner choroid and RNLF thickness in the 6−10 years groups show the effect of PEX material and the importance of time.

Correlation of optical coherence tomography and Doppler ultrasonography findings in pseudoexfoliation syndrome

PURPOSE

We aimed to investigate the correlation between the color Doppler imaging (CDI) results and parameters determined by spectral domain optical coherence tomography (SD-OCT) in cases with pseudoexfoliation syndrome (XFS).

METHODS

99 participants were included in this prospective study. Retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), optic nerve head (ONH) measurements were recorded. Perfusions of the ophthalmic artery (OA) and central retinal artery (CRA) were determined and resistivity indices (RI) were calculated.

RESULTS

No statistically significant differences were determined between the groups regarding the RNFL and ONH parameters. Only the minimum GCC thickness value was determined to be reduced in XFS group (n = 49) when compared to the controls (n = 50) (p = 0.018). The OA-RI and CRA-RI values of XFS group were significantly higher than the control group (p < 0.001 and p = 0.001). In XFSs, negative correlations were present between OA-RI and the minimum, average, inferior and inferotemporal regions of GCC thickness (r = - 0.448 p = 0.001, r = - 0.275 p = 0.040, r = - 0.295 p = 0.027, r = - 0.304 p = 0.024, respectively), and also between CRA-RI and minimum GCC values (r = - 0.317, p = 0.017). While a significant relationship was present between age and OA-RI and CRA-RI values in controls, no such correlation was present in XFSs.

CONCLUSIONS

The vascular resistance increased with age in controls, whereas it was independent of age in XFS group. In XFSs, RIs correlated significantly with certain GCC values, but not with RNFL and ONH parameters. It would be beneficial to follow the XFS with CDI as it provides supportive parameters to GCC in order to recognize early changes in XFS.

Optical coherence tomography angiography: an overview of the technology and an assessment of applications for clinical research

In recent years, ophthalmology has experienced significant developments with respect to imaging modalities. Optical coherence tomography angiography is one such technology that seeks to improve diagnostics for retinal diseases. Using standard structural ocular coherence tomography hardware, optical coherence tomography angiography demonstrates the ability to non-invasively visualise the vasculature in the retina and the choroid with high resolution, allowing greater insight into retinal vascular pathologies. In addition, retinal and choroidal vessel density and blood flow can be quantified, offering potential to assist in the diagnosis of a variety of retinal diseases. To date, numerous retinal diseases, such as open-angle glaucoma, have been found to possess a vascular component. Specifically, ischaemia of the optic nerve head and lamina cribrosa has been theorised as a causative factor in ganglion cell death; however, confirmation of this mechanism has been prohibited by the limitations of currently existing imaging modalities. Optical coherence tomography angiography provides clear imaging of these regions and the possibility to elucidate further understanding of vascular factors that contribute to glaucoma development and progression. Furthermore, this imaging modality may provide insight to neural pathologies with vascular components such as Alzheimer's disease. Herein, the authors discuss the theory of operation for optical coherence tomography angiography and the current findings from pilot studies with a focus on open-angle glaucoma. In addition, speculation is offered for future applications of the technology to study other diseases with microvascular contributions.

Evaluation of the Macular Choroidal Thickness Using Spectral Optical Coherence Tomography in Pseudoexfoliation Glaucoma

PURPOSE

To evaluate the choroidal thickness (CT) in pseudoexfoliative (PEX) glaucoma and age-matched healthy subjects using spectral optical coherence tomography (SD-OCT).

PATIENTS AND METHODS

In this prospective study, 32 eyes of 32 PEX glaucoma patients and 30 eyes of 30 age-matched healthy subjects were enrolled. The CT is measured perpendicularly (from the outer edge of the hyperreflective retinal pigment epithelium to the inner sclera) at the fovea, and 1.5 mm temporal, 3.0 mm temporal, 1.5 mm nasal, and 3.0 mm nasal to the fovea using SD-OCT (RTVue-100).

RESULTS

The groups were similar regarding the mean age and axial length values (both, P>0.05). The CT measurements were 182.12 ± 39.88 and 201.56 ± 32.00 μm at 1.5 mm nasal to the fovea (P=0.039), and 126.47 ± 32.12 and 146.60 ± 31.37 μm at 3.0 mm nasal to the fovea (P=0.015) in the PEX glaucoma and control groups, respectively. There were no significant differences in the subfoveal and temporal CT measurements among the 2 groups (all, P>0.05).

CONCLUSIONS

The findings of this study indicate that PEX glaucoma causes significant thinning in the nasal choroid. Thus, measuring the CT with SD-OCT may be the way of better clarification of the relationship between PEX and glaucomatous optic neuropathy.

Evaluation of Retinal Nerve Fiber Layer and Ganglion Cell Complex Thickness in Unilateral Exfoliation Syndrome Using Optical Coherence Tomography

PURPOSE

To evaluate retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness by using optical coherence tomography in unilateral exfoliation syndrome (XFS) and to assess whether exfoliation itself is an independent risk factor for glaucomatous optic nerve damage.

MATERIALS AND METHODS

Thirty exfoliative eyes of unilateral XFS cases, 30 fellow eyes of unilateral exfoliation, and 30 eyes of healthy subjects were enrolled the study. Peripapillary RNFL and macular GCC thickness measurements by Cirrus HD OCT (Carl Zeiss Meditec, Dublin, CA) were performed on all subjects.

RESULTS

RNFL thickness in superior quadrant was significantly different between groups (P=0.025) and it was thinner in XFS than healthy subjects (P=0.020). All GCC parameters except GCC thickness in inferior quadrant were significantly different between groups (P=0.110 for inferior quadrant, P<0.046 for other GCC parameters). GCC were thinner in XFS than healthy subjects except inferior and inferonasal quadrants (P=0.091, 0.051 for inferior and inferonasal quadrants, respectively, P<0.039 for other GCC parameters). Minimum GCC thickness, GCC thicknesses in superior, and inferonasal quadrants were significantly thinner in fellow eyes than healthy subjects (P=0.011, 0.013, 0.047, respectively).

CONCLUSIONS

XFS is related with thinner RNFL and GCC even in normal intraocular pressure values, similar optic disc parameters and visual field results. XFS may be an independent risk factor for glaucomatous optic nerve damage. So, further studies are needed to evaluate whether exfoliation itself is an independent risk factor for optic nerve damage.

Effects of dorzolamide/timolol fixed combination on retrobulbar hemodynamics in pseudoexfoliative glaucoma

In our study we aimed to evaluate the short-term effects of dorzolamide/timolol on ocular perfusion pressure and retrobulbar blood flow in patients with pseudoexfoliative glaucoma (PXG). This prospective observational cross-sectional study enrolled 22 eyes of 22 newly-diagnosed patients with PXG in a single center. All of the patients received a fixed combination of dorzolamide/timolol. Besides routine ophthalmologic examination, the retrobulbar hemodynamic parameters in the ophthalmic artery, central retinal artery, and short posterior ciliary arteries were measured in all participants at baseline and the 3(rd) month using color Doppler imaging. The mean intraocular pressure (IOP) was 22.3 ± 2.1 mmHg at baseline and reduced to 17.4 ± 2.3 mmHg at the 3(rd) month (p < 0.05). None of the retrobulbar parameters, except peak systolic velocity and resistive index in temporal short posterior ciliary arteries, changed significantly on therapy with dorzolamide/timolol fixed combination when the results were analyzed at Month 3. The drug significantly decreased the peak systolic velocity (p = 0.044) and reduced the resistive index in 0.04 units, 95% confidence interval 0.03-0.05, (p < 0.001) in the temporal short posterior ciliary arteries. This study reports that the retrobulbar hemodynamics might be affected less than expected by dorzolamide/timolol fixed combination in patients with PXG although the reduction of IOP was statistically significant.

Scanning laser polarimetry in eyes with exfoliation syndrome

PURPOSE

To compare retinal nerve fiber layer thickness (RNFLT) of normotensive eyes with exfoliation syndrome (XFS) and healthy eyes.


METHODS

Sixty-four consecutive individuals with XFS and normal office-time intraocular pressure (IOP) and 72 consecutive healthy controls were prospectively enrolled for a cross-sectional analysis in this hospital-based observational study. The GDx-VCC parameters (temporal-superior-nasal-inferior-temporal [TSNIT] average, superior average, inferior average, TSNIT standard deviation (SD), and nerve fiber indicator [NFI]) were compared between groups. Correlation between various clinical parameters and RNFLT parameters was investigated with Spearman coefficient. 


RESULTS

The NFI, although within normal limits for both groups, was significantly greater in the XFS group compared to controls: the respective median and interquartile range (IQR) values were 25.1 (22.0-29.0) vs 15.0 (12.0-20.0), p<0.001. In the XFS group, all RNFLT values were significantly lower compared to controls (p<0.001). However, they were all within the normal clinical ranges for both groups: TSNIT average median (IQR): 52.8 (49.7-55.7) vs 56.0 (53.0-59.3) µm; superior average mean (SD): 62.3 (6.7) vs 68.8 (8.2) µm; inferior average mean (SD): 58.0 (7.2) vs 64.8 (7.7) µm, respectively. TSNIT SD was significantly lower in the XFS group, median (IQR): 18.1 (15.4-20.4) vs 21.0 (18.4-23.8), p<0.001. There was no systematic relationship between RNFLT and visual acuity, cup-to-disc ratio, IOP, central corneal thickness, Humphrey mean deviation, and pattern standard deviation in either group. 


CONCLUSIONS

Compared to control eyes, polarimetry-determined RNFLT was lower in XFS eyes with normal IOP. Therefore, close monitoring of RNFLT may facilitate early identification of those XFS eyes that convert to exfoliative glaucoma.

The impact of intraocular pressure reduction on retrobulbar hemodynamic parameters in patients with open-angle glaucoma

PURPOSE

To assess the retrobulbar hemodynamic parameters in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (PCA) after decreasing elevated intraocular pressure (IOP) in patients with open-angle glaucoma (OAG) by using color Doppler imaging.

METHODS

A total of 46 eyes from 46 patients with OAG, with elevated IOP, were consecutively included in this prospective study. Peak-systolic velocity, end-diastolic velocity, and Pourcelot resistivity index were assessed in the OA, CRA, and PCA. The IOP was measured with Goldmann applanation tonometer (GAT) and the dynamic contour tonometer (DCT), 3 times respectively. Ocular pulse amplitude (OPA) appeared during the DCT measurement.

RESULTS

After decreasing the elevated IOP, measured with both GAT and DCT, the retrobulbar parameters showed no differences as compared with baseline measurements. After Bonferroni correction (p ≤ 0.0042, alpha/12), statistical significance appeared in retrobulbar hemodynamics only in DCT (29.3 ± 6.4 vs 15.5 ± 4.2 mmHg), GAT (33.0 ± 8.3 vs 15.8 ± 7.0 mmHg), and OPA measurements (4.1 ± 1.3 vs 2.7 ± 1.4 mmHg), in comparison to baseline. There was no correlation between the changes in IOP measured with either DCT or GAT and the changes in the retrobulbar hemodynamic parameters (p>0.05 for all).

CONCLUSIONS

The results of our study suggested a lack of correlation between the changes in IOP, measured with either DCT or GAT, and the changes in the retrobulbar hemodynamic parameters. The results of our study might suggest that the blood flow disturbances found in glaucoma patients are independent of the IOP.

Use of colour Doppler imaging in ocular blood flow research

The main objective of this report is to encourage consistent quality of testing and reporting within and between centres that use colour Doppler imaging (CDI) for assessment of retrobulbar blood flow. The intention of this review is to standardize methods in CDI assessment that are used widely, but not to exclude other approaches or additional tests that individual laboratories may choose or continue to use.

The association of ocular blood flow with haemorheological parameters in primary open-angle and exfoliative glaucoma

PURPOSE

To evaluate the ocular blood flow velocities and haemorheological parameters in patients with primary open-angle glaucoma (POAG), exfoliative glaucoma (XFG) and exfoliation syndrome (XFS) and to compare their results with those of healthy controls.

METHODS

Twenty-five patients with POAG (group 1), 25 patients with XFG (group 2), 25 patients with XFS (group 3) and 25 healthy controls (group 4) were included in the study. Ocular blood flow velocities of ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCAs) were measured using colour Doppler imaging (CDI). Haemorheological parameters (erythrocyte elongation and aggregation index, aggregation amplitude, aggregation half-life, plasma viscosity, haematocrit) were measured in venous blood samples of all patients.

RESULTS

The peak systolic velocity (PSV) and end-diastolic velocity (EDV) values were lower and resistive indices (RI) were higher for the OA, CRA and SPCA of glaucomatous (groups 1 and 2) patients compared with those of controls (group 4) (PSV: OA, 40.4 ± 11.3 versus 52.6 ± 12.8 cm/second, p < 0.001; CRA, 12.9 ± 2.9 versus 15.3 ± 4.2 cm/second, p = 0.02; SPCA, 21.7 ± 6.6 versus 26.6 ± 8.3 cm/second, p = 0.013) (EDV: OA, 10.3 ± 4.3 versus 14.2 ± 5.1 cm/second, p < 0.001; CRA, 3.7 ± 1.1 versus 4.5 ± 1.3 cm/second, p = 0.025; SPCA, 5.2 ± 1.8 versus 7.7 ± 3.2 cm/second, p = 0.001) (RI: OA, 0.75 ± 0.05 versus 0.66 ± 0.07, p < 0.001; CRA, 0.73 ± 0.08 versus 0.68 ± 0.10, p = 0.223; SPCA, 0.70 ± 0.10 versus 0.63 ± 0.11, p = 0.004). There were no statistically significant differences between the haemorheological parameters of glaucomatous and non-glaucomatous patients. The reduction in ocular blood flow velocities in groups 1, 2 and 3 were not associated with changes in haemorheological parameters.

CONCLUSION

Our results suggest that impairment of the retrobulbar blood flow in POAG and XFG is not associated with alterations in haemorheological parameters.

Scanning laser ophthalmoscopic parameters of eyes with exfoliation syndrome

PURPOSE

To evaluate optic nerve head (ONH) characteristics in patients with exfoliation syndrome (EXS).

METHODS

This was a cross-sectional, observational study in which 73 eyes from 73 patients with EXS and 93 eyes from 93 age-matched healthy subjects who met the inclusion criteria were included. Topographic measurements of the ONH and peripapillary retinal nerve fiber layer (RNFL) thickness were performed by confocal scanning laser ophthalmoscopy, using a Heidelberg retina tomograph. Outcomes of interest were studied by Student t test and chi-squared test.

RESULTS

EXS patients and age-matched controls did not differ in ONH parameters. Nevertheless, the mean cup depth and height variation contour values were higher in the normal subjects (P = 0.07, P = 0.056, respectively). Mean RNFL thickness was 0.22 +/- 0.06 mm in the EXS group and 0.26 +/- 0.06 mm in the control group, (P = 0.001). Likewise, the RNFL cross-sectional area was significantly lower in exfoliative eyes (1.16 +/- 0.35 mm(2)) than in those of the control group (1.31 +/- 0.33 mm(2)) (P = 0.006).

CONCLUSIONS

No significant differences in ONH parameters between EXS patients and age-matched healthy subjects were observed; however, RNFL measurements in eyes with EXS showed lower values.

Predictors for visual field progression and the effects of treatment with dorzolamide 2% or brinzolamide 1% each added to timolol 0.5% in primary open-angle glaucoma

PURPOSE

This study aims to identify progression factors in patients with primary open-angle glaucoma (POAG), including the effects of treatment with dorzolamide 2% or brinzolamide 1%, each added to timolol 0.5%.

METHODS

A sample of 161 POAG patients were prospectively randomized to receive either dorzolamide 2% (DT) or brinzolamide 1% (BT) b.i.d., each added to timolol 0.5%, during a 60-month, evaluator-masked study. Progression was determined by perimetric criteria. Factors associated with visual field progression were estimated using a conditional Cox hazard model with patient intraclass correlation and were expressed as hazard ratios (HRs) with 95% confidence intervals (95% CIs).

RESULTS

Predictive baseline factors were lower diastolic blood pressure (DBP), lower mean arterial pressure (MAP), antihypertensive treatment, lower end-diastolic velocity (EDV) in the ophthalmic artery (OA) and short posterior ciliary artery (SPCA), and a higher resistivity index (RI) in the OA and SPCA. Progression risk decreased by approximately 30% and 20% with each centimetre per second increase of EDV in the OA and SPCA, respectively, from baseline to the last follow-up visit. Each RI decrease (or increase) of 0.01 unit in the OA or SPCA was associated with an approximate 20% decrease (or increase) in risk for progression. In a multivariate analysis, progression risk was significantly lower in eyes treated with DT (HR=0.65, 95% CI 0.41-0.90) compared with those treated with BT.

CONCLUSIONS

Progression increased with lower DBP, lower MAP, antihypertensive medication, lower EDV in the OA and SPCA, and higher RI in the OA and SPCA. The risk for progression in patients treated with DT was half that in patients treated with BT.

Posture-induced intraocular pressure changes: considerations regarding body position in glaucoma patients

Although glaucoma is a multifactorial disease, elevated intraocular pressure (IOP) remains the most important known risk factor. Different systemic and local factors are thought to influence an individual's IOP. There can be a clinically significant rise in IOP when going from upright to horizontal or inverted body positions. Although there is a significant interindividual variability, the magnitude of the IOP change is greater in glaucomatous eyes. As patients usually spend a significant portion of their lives in the horizontal position, mainly during sleep, this is highly relevant. In this review we discuss the relationship between postural changes and IOP fluctuation, including changes in both body and head position. The possible mechanisms involved and the main implications for glaucomatous eyes are discussed. Finally, considerations with regard to sleep position in glaucoma patients are made based on evidence in the literature.

A comparison of the long-term effects of dorzolamide 2% and brinzolamide 1%, each added to timolol 0.5%, on retrobulbar hemodynamics and intraocular pressure in open-angle glaucoma patients

PURPOSE

To compare the effect on the retrobulbar hemodynamics and intraocular pressure (IOP) of dorzolamide 2% and brinzolamide 1%, each added to timolol 0.5% in patients with primary open-angle glaucoma (POAG).

METHODS

146 POAG patients were prospectively randomized to receive either dorzolamide 2% or brinzolamide 1% BID, each added to timolol 0.5%, during a 60-month evaluator-masked study. At baseline and every 6 months for 60 months, we measured the retrobulbar hemodynamic parameters in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCA) using color Doppler imaging (CDI), intraocular pressure (IOP), and blood pressure measurements.

RESULTS

Dorzolamide significantly increased the end-diastolic velocity (EDV) in the OA in 1.22 cm/s, 95% confidence interval (95% CI) 0.90-1.56 cm/s, P < 0.001 and reduced the resistivity index (RI) in the OA in 0.04 units, 95% CI 0.03-0.05, P < 0.001. None of the retrobulbar parameters changed significantly on therapy with brinzolamide when the results were analyzed at month 60. Both dorzolamide and brinzolamide significantly decreased IOP (-4.3, 95% CI -4.5 to -4.2 mmHg and -4.3, 95% CI -4.4 to -4.2 mmHg, respectively). Dorzolamide significantly reduced the RI in the OA from 0.74 (0.02) to 0.70 (0.02), CRA from 0.66 (0.02) to 0.62 (0.02), and SPCA from 0.66 (0.02) to 0.62 (0.02), P < 0.001, respectively.

CONCLUSIONS

Our results suggest augmented retrobulbar blood flow after 5 years of treatment with dorzolamide but not with brinzolamide, each added to timolol, in POAG patients.