Carlos Marques-Neves

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).

Ophthalmic Artery Doppler Waveform Changes Associated with Increased Damage in Glaucoma Patients

PURPOSE To characterize Doppler waveform variables (early systolic acceleration [ESA] and systolic/diastolic mean velocity ratios [Sm/Dm]) of the Ophthalmic Artery (OA) by color Doppler imaging (CDI) in eyes with primary open-angle glaucoma (POAG). METHODS Analysis of CDI examinations of the retrobulbar circulation of patients with POAG (n = 102), normal tension glaucoma (NTG, n = 89), and healthy controls (n = 59) by a condition-masked investigator. One-way ANOVA, chi-square, and Spearmans rank correlation tests were used to determine differences, establish comparisons, and to explore associations between variables, respectively. RESULTS The overall Doppler waveform presented a shift to the right in the glaucoma groups, with significantly lower Sm/Dm ratios when compared to the control group (healthy: 2.94 ± 0.86, POAG: 2.60 ± 0.67, NTG: 2.63 ± 0.84; P = 0.01). ESA was significantly lower in the glaucoma groups (healthy: 688.8 ± 484 cm·s(-2), POAG: 548.1 ± 419 cm·s(-2), NTG: 548.5 ± 337 cm·s(-2); P = 0.03). No statistical differences were, however, detected in the OA velocities or resistance index (P ranged between 0.08 and 0.96). In the glaucoma groups, waveform parameters such as ESA, acceleration time, and systolic mean velocities correlated with systemic blood pressure variables (P < 0.05). In these groups, negative correlations were detected between Sm/Dm ratios and the degree of visual field defects (POAG: P = 0.01; r = -0.25) and retinal nerve fiber layer thickness (NTG: P = 0.02; r = -0.25). CONCLUSIONS The pattern of blood flow velocities in the OA throughout the cardiac cycle seems to be altered in glaucoma patients. Further studies on how systemic blood pressure affects waveform variables in glaucoma patients may provide a better understanding of an underlying vascular dysfunction.

Intrinsic vasomotricity and adrenergic effects in a model of isolated rabbit eye

Purpose:  We aimed to investigate the responsiveness of the ocular arteries to adrenergic drugs in a model of perfused isolated rabbit eye.

Visual field loss in optic disc drusen patients correlates with central retinal artery blood velocity patterns

(1) To characterize the retrobulbar circulation in patients with optic disc drusen (ODD) using colour Doppler imaging; (2) to explore the differences in retrobulbar hemodynamics in patients with primary open‐angle glaucoma (POAG).

Cataract Surgery and Intraocular Pressure

Cataract surgery is one of the most performed surgeries in the developed world. In addition to its significant impact on visual acuity, phacoemulsification has been hailed as a potential intraocular pressure (IOP)-lowering procedure. While current evidence suggests an overall significant and sustained decrease in IOP to exist after cataract surgery, the specific ocular characteristics that could help predict which patients are likely to benefit from this IOP-lowering effect remain unclear. This definition is important in glaucoma patients if this surgery is to be used in the treatment for this disease. Our review aims to summarize the literature on the subject, depicting possible mechanisms behind this IOP decrease, which type of patients are more likely to benefit from this surgery for IOP-lowering purposes and ultimately help optimizing disease management for the increasing number of patients with concomitant glaucoma and cataract.

Endothelin-1 effects on spontaneous oscillations in choroidal arterioles

Acta Ophthalmol. 2010: 88: 742–747

Ocular Pulse Amplitude and Doppler Waveform Analysis in Glaucoma Patients

To determine the correlation between ocular blood flow velocities and ocular pulse amplitude (OPA) in glaucoma patients using colour Doppler imaging (CDI) waveform analysis.

Review on Dynamic Contour Tonometry and Ocular Pulse Amplitude

Intraocular pressure (IOP) measurement is the cornerstone of the management of glaucoma patients. The gold standard for assessing IOP is Goldmann applanation tonometry (GAT). Recently, the dynamic contour tonometer (DCT) has become available. While both devices provide reliable IOP measurements, the results are not interchangeable. DCT has the advantage of measuring an additional parameter: ocular pulse amplitude (OPA). OPA is defined as the difference between systolic and diastolic IOP and represents the pulsatile wave front produced by the varying amount of blood in the eye during the cardiac cycle. It has been shown to vary with ocular structural parameters, such as axial length, corneal thickness, and ocular rigidity, as well as with systemic variables like heart rate, blood pressure, and left ventricular ejection fraction. Although the existence of some of these associations is still controversial, the clinical relevance of OPA has been consistently suggested, especially in glaucoma. Further research on this intriguing parameter could not only provide insight into glaucoma pathophysiology but also help integrate this variable into clinical practice.

Xen Gel Stent Internal Ostium Occlusion: Ab-interno Revision

Minimally invasive glaucoma surgery aims to provide a safer and less-invasive means of reducing IOP compared with traditional surgery, with the goal of reducing the need for topical medications. The XEN gel stent is an ab-interno minimally invasive glaucoma surgery device that approaches intraocular pressure reduction by creating a subconjunctival drainage pathway. As with any new device there is lack of experience and knowledge about its long-term results in terms of efficacy, technique, and complications. We report a clinical case of a XEN blood clot internal ostium obstruction and how it was managed. The ab-interno approach with microforceps seems a minimally invasive, safe, and effective procedure.

Higher optic nerve sheath diameters are associated with lower ocular blood flow velocities in glaucoma patients

PurposeTo investigate the relationship between optic nerve sheath diameter (ONSD) and retrobulbar blood flow velocities, as measured by color Doppler imaging (CDI) in glaucoma patients.MethodsWe performed a prospective, randomized, observer-masked study involving a total of 197 subjects. Once enrolled, they were divided by three groups: healthy controls (n = 51), normal-tension glaucoma patients (NTG, n = 58), and primary, open-angle glaucoma patients (POAG, n = 88). All subjects underwent a general ophthalmological examination, an ultrasound-based assessment of the ONSD, and a hemodynamic study of the retrobulbar vascularization using CDI. Non-parametric tests, chi-square contingency tables, and the Deming correlations were used to explore differences and correlations between variables in the diagnostic groups.ResultsONSD was not different between experimental groups (p = 0.28). ONSD correlated positively with the pulsatility index of the ophthalmic artery in healthy individuals (p = 0.007), but not in glaucoma patients (NTG: p = 0.41; POAG: p = 0.22). In NTG patients, higher ONSD values were associated with lower end-diastolic and mean flow velocities in the short ciliary arteries (p = 0.005 in both correlations). No such correlation was found in healthy nor POAG groups (p range between 0.15 to 0.96). ONSD was not associated with any CDI-related variable of the central retinal artery in any cohort. Venous outflow velocities were not associated with ONSD in any of the three groups.ConclusionsONSD is negatively correlated with retrobulbar blood flow velocities in glaucoma patients, but not in healthy controls.