Retrobulbar Hemodynamics and Visual Field Progression in Normal Tension Glaucoma: A Long-Term Follow-Up Study

Multipressure Dial Goggle Effects on Circumpapillary Structure and Microvasculature in Glaucoma Patients

PURPOSE

To evaluate the effects of pressure changes induced by a multipressure dial (MPD) on circumpapillary retinal nerve fiber layer (RNFL) and capillary density (CD) measurements in patients with glaucoma using OCT angiography (OCTA).

DESIGN

Prospective interventional study.

PARTICIPANTS

Twenty-four patients with primary open-angle glaucoma.

METHODS

One eye of each patient underwent negative pressure application with the MPD. The MPD alters intraocular pressure (IOP) relative to atmospheric pressure by generating a negative pressure vacuum within a goggle chamber that is placed over the eye. Each participant underwent serial high density OCTA imaging (AngioVue) of the optic nerve head at different negative pressure increments of -5 mmHg, starting from 0 mmHg, ending at -20 mmHg, and then returning to baseline. Images were acquired after 2 minutes of sustained negative pressure at each target pressure to allow for stabilization of the retinal structures and microvasculature. The RNFL thickness and CD measurements were automatically calculated using the native AngioVue software, and then exported for analysis.

MAIN OUTCOME MEASURES

The influence of different levels of negative pressure on circumpapillary RNFL thickness and CD measurements, assessed by a linear mixed-effects model with repeated measures.

RESULTS

The mean (± SD) age was 71.0 years (± 7.8 years), the baseline IOP was 17.5 mmHg (± 3.6 mmHg), and there was a mean 24-2 mean deviation of -2.80 dB (± 2.55 dB). Serial circumpapillary CD measurements showed a statistically significant dose-dependent increase from baseline, without negative pressure application, to the maximum negative pressure application of -20 mmHg (difference, 2.27%; P = 0.010). Capillary density measurements then decreased symmetrically when lowering the negative pressure to baseline. Circumpapillary CD measurements at target negative pressures of -10 mmHg, -15 mmHg, and -20 mmHg were significantly higher than the baseline measurements (all P values < 0.05). Circumpapillary RNFL thickness remained the same throughout different levels of negative pressure.

CONCLUSIONS

Circumpapillary CD measurements showed a dose-dependent increase with the induction of negative pressure, while RNFL thickness measurements remained unchanged.

Multilayer Macula Vessel Density and Visual Field Progression in Glaucoma

PURPOSE

To evaluate the association of macular superficial vessel density (SVD) and projection-resolved deep vessel density (DVD) with past visual field (VF) progression in patients with primary open-angle glaucoma.

DESIGN

Retrospective cohort.

METHODS

In this longitudinal study, 208 eyes of 147 patients with glaucoma from the Diagnostics Innovations in Glaucoma Study were included. Eligible participants were required to have at least five 24-2 VF tests over a minimum follow-up period of 3 years before macular optical coherence tomography angiography imaging. VF progression was defined based on both event-based pointwise linear regression and trend-based methods. The association of macular SVD and DVD with the probability and rate of past VF progression was evaluated using a linear mixed effects model.

RESULTS

Fifty-two (25%) eyes had VF progression based on the pointwise linear regression based criterion at the end of a mean ± standard deviation follow-up duration of 6.9 ± 1.2 years. In the event-based multivariable analysis, a lower baseline SVD was associated with a higher likelihood of past VF progression (odds ratio per 1% lower. 1.28; 95% confidence interval, 1.02-1.59). Similarly, in the trend-based multivariable analysis, lower macular SVD was associated with a faster past rate of mean deviation decline (coefficient = -0.03 dB/year; 95% confidence interval, -0.04 to -0.01). Event-based and trend-based analyses found no significant associations for macular DVD with the likelihood/rate of past VF progression (P > .05).

CONCLUSIONS

Lower macular SVD, and not DVD, was associated with a higher probability of past VF progression. Macular optical coherence tomography angiography imaging shows promise for identifying eyes at risk of VF progression in patients with glaucoma.

Association of ocular blood flow and contrast sensitivity in normal tension glaucoma

Purpose

To investigate the relationship of ocular blood flow (via arteriovenous passage time, AVP) and contrast sensitivity (CS) in healthy as well as normal tension glaucoma (NTG) subjects.

Design

Mono-center comparative prospective trial

Methods

Twenty-five NTG patients without medication and 25 healthy test participants were recruited. AVP as a measure of retinal blood flow was recorded via fluorescein angiography after CS measurement using digital image analysis. Association of AVP and CS at 4 spatial frequencies (3, 6, 12, and 18 cycles per degree, cpd) was explored with correlation analysis.

Results

Significant differences regarding AVP, visual field defect, intraocular pressure, and CS measurement were recorded in-between the control group and NTG patients. In NTG patients, AVP was significantly correlated to CS at all investigated cpd (3 cpd: r =  − 0.432, p< 0.03; 6 cpd: r =  − 0.629, p< 0.0005; 12 cpd: r =  − 0.535, p< 0.005; and 18 cpd: r =  − 0.58, p< 0.001), whereas no significant correlations were found in the control group. Visual acuity was significantly correlated to CS at 6, 12, and 18 cpd in NTG patients (r =  − 0.68, p< 0.002; r =  − 0.54, p< .02, and r =  − 0.88, p< 0.0001 respectively), however not in healthy control patients. Age, visual field defect MD, and PSD were not significantly correlated to CS in in the NTG group. MD and PSD were significantly correlated to CS at 3 cpd in healthy eyes (r = 0.55, p< 0.02; r =  − 0.47, p< 0.03).

Conclusion

Retinal blood flow alterations show a relationship with contrast sensitivity loss in NTG patients. This might reflect a disease-related link between retinal blood flow and visual function. This association was not recorded in healthy volunteers.

Prevalence and Predictors of Ocular Complications in Obstructive Sleep Apnea Patients: A Cross-sectional Case-control Study

Purpose:

This study sought to identify the magnitude and the possible risk factors of ocular complications in patients with Obstructive Sleep Apnea (OSA).

Methods:

A hospital-based cross-sectional study with a nested case-control design was conducted. Qualifying study subjects were patients who had been diagnosed with moderate to severe OSA (AHI index of ≥ 5, n=80), and control subjects (n=20) who had an AHI index of ≤ 5 (“normal”). Study participants were recruited from Mansoura University Hospital’s Sleep Disorders Clinic in Mansoura, Egypt.Selected subjects were assessed for ocular complications at Mansoura Univerity Hospital Ophthalmic Center, (Mansoura), Egypt. An ophthalmic history was recorded, and opthalmic testing was carried out. The testing included unaided visual acuity measurement, refraction, best-corrected visual acuity measurement, slit lamp bio-microscopic evaluation of the anterior segment and anterior segment photography, dilated fundus examination, intraocular pressure measurement, fundus photo, and fluorescein angiography, and visual field assessment. Various tests of OSA symptoms were also monitored, including the AHI, lowest oxygen concentrations and desaturation index plus the overall severity index. .

Results:

It was found that OSA patients n=28 (35%), n=24 (30%), n=4 (5%) had senile cataract, normal tension glaucoma, and retinal ischemia, respectively, with an overall prevalence of 45%. Additionally, the OSA group had seven times greater risk (OR=7.36, 95%CI: 1.6-33.86) of vision-threatening disorders compared to the controls. OSA patients were observed to be at a greater risk of senile cataract 28 (35%), normal tension glaucoma 24 (30%), retinal ischemia 4 (5%) and conjunctival hyperemia and dry eye (OR=3.77, 95%CI: 1.02-13.95, OR=4.36, 95%CI: 1.26-17.08). Also, multivariate logistic regression analysis testing showed that the lowest oxygen saturation index was the only significant predictor negatively associated with vision-threatening disorders (OR=0.84, 95%CI: 0.75-0.93).

Conclusion:

The risk of vision-threatening and non-threatening ocular disorders is higher among OSA cases. The lowest oxygen saturation index was the only significant predictor of vision-threatening disorders. These findings support the recommendation that a full ophthalmic examination should be carried out on patients with confirmed OSA.

Ocular Hemodynamics in Acute Nonarteritic Anterior Ischemic Optic Neuropathy Compared With Normal Tension Glaucoma

PURPOSE

The purpose of this study was to evaluate ocular hemodynamics in patients with a disease believed to be related to a chronic vascular damage [ie, normal tension glaucoma (NTG)] in comparison with an entity with an acute ischemic impact on the optic nerve [ie, acute nonarteritic anterior ischemic optic neuropathy (NAION)].

MATERIALS AND METHODS

Blood-flow velocities [peak systolic velocity (PSV), enddiastolic velocity (EDV)] of the ophthalmic artery (OA), central retinal artery (CRA), and nasal and temporal posterior ciliary arteries were measured using color Doppler imaging. Resistive index (RI) of all vessels was calculated (PSV-EDV/PSV). A total of 41 patients suffering from acute NAION (onset of symptoms <10 d) and 64 age-matched patients suffering from NTG were included in this prospective study.

RESULTS

No significant differences were recorded for either age or intraocular pressure inbetween the 2 groups. Systolic blood pressure was significantly higher in the NAION group, whereas no significant differences were recorded for the diastolic blood pressure. Only 3 color Doppler imaging parameters were found to differ significantly. The PSV (P<0.005) and EDV (P<0.02) in the CRA were significantly higher in NTG patients. Furthermore, the RI in the OA was significantly higher in the NAION patients (P<0.005).

CONCLUSIONS

Decreased blood-flow velocities in the CRA and a higher RI in the OA can be recorded in NAION patients as compared with NTG. No differences with regard to the posterior ciliary arteries' velocities were recorded. Ocular hemodynamics are suspected to play a critical role in NAION and NTG, whereas the blood-flow disturbances seem to be more severe in NAION than in NTG.

Color Doppler imaging of the retrobulbar circulation in progressive glaucoma optic neuropathy

It is known that elevated intraocular pressure (IOP) is the primary risk factor for glaucoma. Recently, more and more evidences have shown that the vascular deficit also plays an important role in the pathogenesis and progressions of glaucomatous optic neuropathy. This issue is backed up by glaucomatous optic neuropathy (GON) cases drug compensated in which the progression of the disease in one or both eyes is ascertained despite a normal and relatively constant IOP. The present study evaluated the hemodynamic parameters in the retrobulbar circulation in patients with progressive glaucomatous optic neuropathy in one eye, who received compensated medication. The hemodynamic parameters (PSV, EDV, IR) were measured by using color Doppler ultrasound and progression was evaluated by a repeated automated perimetry. The obtained values were statistically analyzed and compared with those obtained for the stable eye.

Survey on retrobulbar blood flow in glaucomatous optic neuropathy (normotensive and hypertensive)

The aim of this study was to analyze the possible differences between retrobulbar blood flows in normotensive glaucomatous optic neuropathy patients versus patients with hypertensive glaucomatous optic neuropathy, with intraocular pressure controlled treatment. All the patients in the study group were subjected to a color Doppler echography of retrobulbar vessels. Afterwards, systolic and diastolic blood velocities were measured in both eyes in ophthalmic artery (OA), central retinal artery (CRA) and posterior ciliary arteries (PCA). The device calculated the Resistivity index Pourcelot (RI) automatically.

Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma

Glaucoma may be caused by an interplay of elevated intraocular pressure (IOP), vascular, genetic, anatomical, brain, and immune factors. The direct assessment of ocular hemodynam-ics offers promise for glaucoma detection, differentiation, and possibly new treatment modalities. All the methods currently in use to measure ocular blood flow have inherent limitations and measure different aspects of ocular blood flow. This review article attempts to provide detailed information on ocular perfu-sion pressure as well as an overview of the newly developed imaging technologies used to investigate ocular blood flow in glaucoma patients.

HOW TO CITE THIS ARTICLE

Mohindroo C, Ichhpujani P, Kumar S. Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma. J Curr Glaucoma Pract 2016;10(3):104-112.