Facteurs vasculaires du glaucome

Retinal vessel architecture and geometry are not impaired in normal-tension glaucoma

To investigate the associations between retinal vessel parameters and normal-tension glaucoma (NTG). We conducted a case-control study with a prospective cohort, allowing to record 23 cases of NTG. We matched NTG patient with one primary open-angle glaucoma (POAG) and one control per case by age, systemic hypertension, diabetes, and refraction. Central retinal artery equivalent (CRAE), central retinal venule equivalent (CRVE), Arteriole-To-Venule ratio (AVR), Fractal Dimension and tortuosity of the vascular network were measured using VAMPIRE software. Our sample consisted of 23 NTG, 23 POAG, and 23 control individuals, with a median age of 65 years (25-75th percentile, 56-74). No significant differences were observed in median values for CRAE (130.6 µm (25-75th percentile, 122.8; 137.0) for NTG, 128.4 µm (124.0; 132.9) for POAG, and 135.3 µm (123.3; 144.8) for controls, P = .23), CRVE (172.1 µm (160.0; 188.3), 172.8 µm (163.3; 181.6), and 175.9 µm (167.6; 188.4), P = .43), AVR (0.76, 0.75, 0.74, P = .71), tortuosity and fractal parameters across study groups. Vascular morphological parameters were not significantly associated with retinal nerve fiber layer thickness or mean deviation for the NTG and POAG groups. Our results suggest that vascular dysregulation in NTG does not modify the architecture and geometry of the retinal vessel network.

Peripapillary and optic nerve head vessel density of glaucoma and healthy subjects from Afro-Caribbean and European descent: A pilot study

PURPOSE

To compare the peripapillary and optic nerve head vessel density (PP-ONH VD) between glaucoma patients (all, early, moderated, and advanced) and healthy subjects of Afro-Caribbean descent (AD) and European descent (ED).

METHODS

This was a cross-sectional study. One eye was evaluated in 90 subjects, including 66 glaucoma patients and 24 healthy subjects, who underwent PP-ONH VD imaging using SPECTRALIS® Optical Coherence Tomography Angiography (OCT-A). We analysed the superficial vascular complex using the AngioTool version 0.6a software. The correlation between the PP-ONH VD and visual field mean deviation (MD) was evaluated using a scatter plot and Spearman's rho correlation coefficient.

RESULTS

Among the healthy subjects, the AD group had a lower superficial PP-ONH VD [43.29±3.25% (mean±standard deviation)] than the ED group (46.06±1.75%) (P=0.016). Overall, superficial PP-ONH VD did not show any significant differences between the total AD and ED glaucoma patients or in the subgroup analyses (early/moderate/advanced) (AD: 32.73±6.70%, 37.11±5.72%, 32.48±5.73%, 27.76±4.74%, respectively; ED: 33.94±6.89%, 38.52±3.82%, 35.56±4.18%; 27.65±6.31%, respectively) (P>0.05 for all). A strong, statistically significant correlation was established between vessel density and mean deviation among AD and ED glaucoma patients (r=0.709 and r=0.704, respectively) (P<0.001 for both).

CONCLUSION

This pilot study shows that healthy subjects of AD had lower peripapillary and optic nerve head superficial vessel density than healthy subjects of ED, but no significant differences were found between AD and ED glaucoma groups (all, early, moderate, or advanced).

[Endothelins and dopamine levels in tears for assessment of neurovascular disorders in glaucoma]

PURPOSE

To estimate the possibility of detection of neurovascular ocular disorders in glaucoma by assessing the content of catecholamines and endothelins in lacrimal fluid.

MATERIAL AND METHODS

The study included 47 patients with primary open-angle glaucoma (POAG). Tear eluate was analyzed by high performance liquid chromatography (HPLC) for catecholamines concentrations, and enzyme-linked immunoassay (ELISA) was used for evaluation of endothelins content.

RESULTS

Endothelin-1 (ET-1) and big endothelin (bET) content in tears of patients with POAG was higher than in healthy controls. Concentration of dopamine (DA) in tears was lower and concentrations of L-dioxyphenylalanine and dihydroxyphenylacetic acid had a tendency for decrease. Noradrenaline content was equal in patients with POAG and controls. Adrenaline was not detected in any tear samples.

CONCLUSION

Multidirectional changes of endothelins and DA levels in tears of patients with POAG was found. The increased concentration of ET-1 and its precursor bET promote vasoconstriction and decrease of aqueous humor outflow. The decrease of DA concentration is typical for neurodegenerative processes. Estimation of DA and endothelins concentrations in tears can enable early detection of neurovascular disorders in glaucoma patients and help evaluate their severity.

Analysis of choroidal thickness in ocular hypertensive patients using enhanced depth imaging optical coherence tomography

This study aimed to compare choroidal thickness between subjects with ocular hypertension (OHT) and normal individuals and explore factors affecting choroidal thickness. This study included 60 untreated newly diagnosed OHT eyes and 60 normal eyes. Choroidal thickness obtained from Cirrus HD-OCT was measured at different locations in the macular and peripapillary regions and compared between the two groups before and after adjusting for potential confounding variables. Regression analysis was performed to figure out factors influencing choroidal thickness. The macular choroidal thickness did not vary significantly between OHT patients and normal controls regardless of locations (all P > 0.05). The average peripapillary choroidal thickness was 167 ± 53 μm in OHT eyes and 185 ± 63 μm in the normal eyes; no significant differences were identified (P = 0.107). Only one of the locations in the temporal area in the OHT group demonstrated significantly thinner peripapillary choroidal thickness as compared to the normal group (P = 0.033). Age was the only significant factor affecting choroidal thickness on multivariate analysis regardless of locations (all P < 0.001). Choroidal thickness of the macular and peripapillary regions in OHT patients is not decreased significantly except one location in the temporal area of the optic disc when comparing with the normal subjects. Anatomic peripapillary choroidal thickness measurements with SD-OCT might be one more tool to track changes in OHT patients.

24-h monitoring devices and nyctohemeral rhythms of intraocular pressure

Intraocular pressure (IOP) is not a fixed value and varies over both the short term and periods lasting several months or years. In particular, IOP is known to vary throughout the 24-h period of a day, defined as a nyctohemeral rhythm in humans. In clinical practice, it is crucial to evaluate the changes in IOP over 24 h in several situations, including the diagnosis of ocular hypertension and glaucoma (IOP is often higher at night) and to optimize the therapeutic management of glaucoma. Until recently, all evaluations of 24-h IOP rhythm were performed using repeated IOP measurements, requiring individuals to be awakened for nocturnal measurements. This method may be imperfect, because it is not physiologic and disturbs the sleep architecture, and also because it provides a limited number of time point measurements not sufficient to finely asses IOP changes. These limitations may have biased previous descriptions of physiological IOP rhythm. Recently, extraocular and intraocular devices integrating a pressure sensor for continuous IOP monitoring have been developed and are available for use in humans. The objective of this article is to present the contributions of these new 24-h monitoring devices for the study of the nyctohemeral rhythms. In healthy subjects and untreated glaucoma subjects, a nyctohemeral rhythm is consistently found and frequently characterized by a mean diurnal IOP lower than the mean nocturnal IOP, with a diurnal bathyphase - usually in the middle or at the end of the afternoon - and a nocturnal acrophase, usually in the middle or at the end of the night.

Eclectic Ocular Comorbidities and Systemic Diseases with Eye Involvement: A Review

Coexistence of several ocular diseases is more frequent than suspected. In spite of the refractive errors, one or more of the following can be detected simultaneously: glaucoma, cataracts, uveitis, age-related macular degeneration, and dry eyes. In addition, as people age, ocular comorbidities are much more usually seen. Specific diseases are openly acknowledged to affect the eyes and vision, such as diabetes mellitus, hypertension blood pressure, arthritis, hyperthyroidism, neurodegenerative disorders, hematologic malignancies, and/or systemic infections. Recent advances in early diagnosis and therapy of the ophthalmic pathologies have reinforced patient options to prevent visual impairment and blindness. Because of this, it is essential not to overlook sight-threatening conditions such as the ocular comorbidities and/or the eye involvement in the context of systemic disorders. Moreover, the important role of the multidisciplinary cooperation to improve and sustain management of patients affected with eclectic ocular comorbidities and/or systemic disorders with eye repercussion is specifically addressed. This review intends to shed light on these topics to help in making opportune diagnosis and appropriately managing the affected patients.