Ocular Pulse Amplitude and Doppler Waveform Analysis in Glaucoma Patients

PURPOSE: To determine the correlation between ocular blood flow velocities and ocular pulse amplitude (OPA) in glaucoma patients using colour Doppler imaging (CDI) waveform analysis. METHOD: A prospective, observer-masked, case-control study was performed. OPA and blood flow variables from central retinal artery and vein (CRA, CRV), nasal and temporal short posterior ciliary arteries (NPCA, TPCA) and ophthalmic artery (OA) were obtained through dynamic contour tonometry and CDI, respectively. Univariate and multiple regression analyses were performed to explore the correlations between OPA and retrobulbar CDI waveform and systemic cardiovascular parameters (blood pressure, blood pressure amplitude, mean ocular perfusion pressure and peripheral pulse). RESULTS: One hundred and ninety-two patients were included [healthy controls: 55; primary open-angle glaucoma (POAG): 74; normal-tension glaucoma (NTG): 63]. OPA was statistically different between groups (Healthy: 3.17 ± 1.2 mmHg; NTG: 2.58 ± 1.2 mmHg; POAG: 2.60 ± 1.1 mmHg; p < 0.01), but not between the glaucoma groups (p = 0.60). Multiple regression models to explain OPA variance were made for each cohort (healthy: p < 0.001, r = 0.605; NTG: p = 0.003, r = 0.372; POAG: p < 0.001, r = 0.412). OPA was independently associated with retrobulbar CDI parameters in the healthy subjects and POAG patients (healthy CRV resistance index: β = 3.37, CI: 0.16-6.59; healthy NPCA mean systolic/diastolic velocity ratio: β = 1.34, CI: 0.52-2.15; POAG TPCA mean systolic velocity: β = 0.14, CI 0.05-0.23). OPA in the NTG group was associated with diastolic blood pressure and pulse rate (β = -0.04, CI: -0.06 to -0.01; β = -0.04, CI: -0.06 to -0.001, respectively). CONCLUSIONS: Vascular-related models provide a better explanation to OPA variance in healthy individuals than in glaucoma patients. The variables that influence OPA seem to be different in healthy, POAG and NTG patients.

Impacto do Diâmetro do Nervo Óptico na Amplitude de Pulso Ocular no Glaucoma Primário de Ângulo Aberto

Introdução: A pressão intra-craniana (PIC) tem sido descrita como estando envolvida no glaucoma primário de ângulo aberto (GPAA). A sua avaliação está contudo limitada pela necessidade de métodos invasivos, como a punção lombar. A ecografia ocular permite uma avaliação indirecta da PIC através da medição do diâmetro da bainha do nervo óptico (NO). Desconhece-se se esta nova variável tem capacidade de modular factores de risco normalmente investigados em doentes com GPAA. Objectivo: Avaliar o impacto do diâmetro da bainha do NO na pressão intra-ocular (PIO) e na amplitude de pulso ocular (OPA) de doentes com GPAA. Métodos: Quinze doentes com GPAA foram submetidos a medição da PIO por tonometria de contorno dinâmico, avaliação topográfica do disco óptico e ecografia ocular modo B com sonda doppler. Apenas o olho com maior dano glaucomatoso foi seleccionado por doente. Resultados: A média do diâmetro da bainha do NO foi de 5,6±0,67mm, a PIO média de 17,8±2,2mmHg e a OPA de 3,1±1,7mmHg. O diâmetro da bainha do NO correlacionou-se negativamente a OPA (r=-0.54, p=0.05), não tendo influenciado a PIO (r=-0,25, p=0,41). Da avaliação hemodinâmica, apenas o índice de resistência da artéria central da retina (CRA) foi influenciado pelo diâmetro da bainha do NO (r=-0.52, p=0.04). Conclusão: O diâmetro da bainha do NO correlaciona-se negativamente com a OPA. Este efeito poderá ser explicado pela alteração da resistência vascular da artéria que atravessa este espaço subaracnoideu, a CRA. O estudo da região retrobulbar e do balanço entre as pressões aí exercidas é assim um campo cuja importância será crescente na avaliação do doente com GPAA.

Intraocular Pressure Correlates with Optic Nerve Sheath Diameter in Patients with Normal Tension Glaucoma

PURPOSE: 1. Identify differences in optic nerve sheath diameter (ONSD) as an indirect measure of intracranial pressure (ICP) in glaucoma patients and a healthy population. 2. Identify variables that may correlate with ONSD in primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG) patients. METHODS: Patients with NTG (n = 46) and POAG (n = 61), and healthy controls (n = 42) underwent B-scan ultrasound measurement of ONSD by an observer masked to the patient diagnosis. Intraocular pressure (IOP) was measured in all groups, with additional central corneal thickness (CCT) and visual field defect measurements in glaucomatous patients. Only one eye per patient was selected. Kruskal-Wallis or Mann-Whitney were used to compare the different variables between the diagnostic groups. Spearman correlations were used to explore relationships among these variables. RESULTS: ONSD was not significantly different between healthy, NTG and POAG patients (6.09 ± 0.78, 6.03 ± 0.69, and 5.71 ± 0.83 respectively; p = 0.08). Visual field damage and CCT were not correlated with ONSD in either of the glaucoma groups (POAG, p = 0.31 and 0.44; NTG, p = 0.48 and 0.90 respectively). However, ONSD did correlate with IOP in NTG patients (r = 0.53, p < 0.001), while it did not in POAG patients and healthy controls (p = 0.86, p = 0.46 respectively). Patient's age did not relate to ONSD in any of the groups (p > 0.25 in all groups). CONCLUSIONS: Indirect measurements of ICP by ultrasound assessment of the ONSD may provide further insights into the retrolaminar pressure component in glaucoma. The correlation of ONSD with IOP solely in NTG patients suggests that the translaminar pressure gradient may be of particular importance in this type of glaucoma.

Hereditary Neuropathy with Liability to Pressure Palsy Presenting with Hand Drop in a Young Child

Hereditary neuropathy with liability to pressure palsy (HNPP) results from the deletion of the PMP22 gene in chromosome 17p11.2. Clinically, it presents with painless pressure palsies, typically in the 2nd and 3rd decades of life, being a rare entity in childhood. We present the case study of a six-year-old male child who presented with left hand drop that he kept for over four weeks. Electrophysiological studies suggested HNPP and genetic studies confirmed it. With this paper, we pretend to create awareness to this entity as a diagnosis to be considered in a child with painless monoparesis and to emphasize the importance of electrophysiological studies in the diagnosis.

Intraocular Pressure in Eyes Receiving Intravitreal Antivascular Endothelial Growth Factor Injections

PURPOSE: The aim of the this study was to determine the effect of intravitreal antivascular endothelial growth factor injections on intraocular pressure (IOP) and identify possible risk factors for the development of increased IOP. MATERIALS AND METHODS: This prospective study included a total of 106 eyes receiving intravitreal injection of bevacizumab as treatment for macular edema or active choroidal neovascularization. IOP was measured by Goldmann applanation tonometry immediately before the intravitreal injection and 5 min, 1 h and 15 days after the procedure. The records of the study patients were reviewed for age, gender, history of glaucoma, diabetes mellitus, phakic status, systemic and topical medication and number of previous injections. Subconjunctival reflux was registered. IOP elevation was defined as IOP ≥21 mm Hg and/or a change from baseline of ≥5 mm Hg recorded at least on two or more measurements on the same visit. RESULTS: Mean preoperative IOP was 15.31 ± 3.90 mm Hg and postoperative IOP values were 27.27 ± 11.87 mm Hg (after 5 min), 17.59 ± 6.24 mm Hg (after 1 h) and 16.86 ± 3.62 mm Hg (after 15 days). The IOP variation was statistically significant between pre- and postoperative measurements (p < 0.05). Subconjunctival reflux was recorded in 11.3%, and in this subgroup the IOP at 5 min and at 1 h was lower than preoperative IOP (p < 0.05). CONCLUSIONS: More than one third of the eyes achieved IOPs >30 mm Hg 5 min after injection. Subconjunctival reflux contributed to a lower mean postoperative IOP (p < 0.05). Considerations for the management include prophylactic IOP lowering with medical therapy and/or preinjection ocular decompression for patients with a history of glaucoma or ocular hypertension and switching to an as-needed injection protocol in patients suffering a marked IOP rise in previous injections. © 2015 S. Karger AG, Basel.