Orbscan Topography in Primary Open-Angle Glaucoma

Purpose: To compare anterior and posterior corneal curvatures between eyes with primary open-angle glaucoma (POAG) and healthy eyes. Methods: This is a prospective, cross-sectional, observer-masked study. A total of 138 white subjects (one eye per patient) were consecutively recruited; 69 eyes had POAG (study group), and the other 69 comprised a group of healthy control eyes matched for age and central corneal pachymetry with the study ones. Exclusion criteria included any corneal or ocular inflammatory disease, previous ocular surgery, or treatment with carbonic anhydrase inhibitors. The same masked observer performed Goldmann applanation tonometry, ultrasound pachymetry, and Orbscan II topography in all cases. Central corneal thickness, intraocular pressure, and anterior and posterior topographic elevation maps were analyzed and compared between both groups. Results: Patients with POAG had greater forward shifting of the posterior corneal surface than that in healthy control eyes (p < 0.01). Significant differences in anterior corneal elevation between controls and POAG eyes were also found (p < 0.01). Conclusions: Primary open-angle glaucoma eyes have a higher elevation of the posterior corneal surface than that in central corneal thickness–matched nonglaucomatous eyes.

Cirurgia de catarata e glaucoma

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Abordagem multidisciplinar do glaucoma congénito primário : caso clínico

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Systemic reduction in glutathione levels occurs in patients with primary open-angle glaucoma

PURPOSE. To assess the level of plasma glutathione in patients with untreated primary open-angle glaucoma. METHODS. Twenty-one patients with newly diagnosed primary open-angle glaucoma and 34 age- and gender-matched control subjects were subjected to a blood analysis to detect the level of circulating glutathione in its reduced and oxidized forms. The effect of age, gender, and systemic blood pressure on circulating glutathione levels was also analyzed. RESULTS. Age had a negative effect on the level of both reduced and total glutathione (P = 0.002, r = -0.52 and P = 0.002, r = -0.52, respectively) in control subjects but not in patients with glaucoma (P > 0.05, r = 0.27, and P > 0.05, r = 0.22, respectively). In the control group, men demonstrated higher levels of both reduced and total glutathione than did women (P = 0.024 and P = 0.032, respectively). After correction for age and gender influences on blood glutathione levels, patients with glaucoma exhibited significantly lower levels of reduced and total glutathione than did control subjects (P = 0.010, F = 7.24 and P = 0.006, F = 8.38, respectively). No differences between study groups were observed in either oxidized glutathione levels or redox index (P > 0.05, F = 0.50; and P > 0.05, F = 0.30, respectively). CONCLUSIONS. Patients with glaucoma exhibit low levels of circulating glutathione, suggesting a general compromise of the antioxidative defense. Copyright © Association for Research in Vision and Ophthalmology.

Transient cardiac ischaemia and abnormal variations in systemic blood pressure in unselected primary open angle glaucoma patients

To investigate the relationship between the occurrence of transient cardiac ischaemic episodes and variations in the ambulatory 24-h blood pressure and heart rate measurements in a group of unselected glaucoma patients.

First-line therapy with latanoprost 0.005% results in improved ocular circulation in newly diagnosed primary open-angle glaucoma patients: a prospective, 6-month, open-label study

Purpose To evaluate the effect of latanoprost 0.005% on the optic nerve head (ONH) and retinal circulation of newly diagnosed and previously untreated primary open-angle glaucoma (POAG) patients. Methods Twenty-two newly diagnosed and previously untreated POAG patients (mean age±SD: 68.38±11.92 years) were included in this longitudinal open-label study. Patients were treated with latanoprost 0.005% once a day. Intraocular pressure (IOP), systemic blood pressure (BP), mean ocular perfusion pressure (MOPP), and ocular perfusion parameters ‘volume’, ‘velocity’, and ‘flow’ measured at the optic nerve head (ONH) and retina by means of Heidelberg Retina Flowmeter system were evaluated during a 6-month follow-up period. Results Treatment with latanoprost 0.005% resulted in a significant decrease in IOP (P<0.0001) and increase in MOPP (P<0.0001). After correcting for changes in MOPP, the blood velocity measured at the ONH level was significantly higher after 6 months of treatment than at baseline (P=0.0310). In addition, blood volume and flow measured at the peripapillary retina level improved after 3 and 6 months of treatment (P=0.0170; P=0.0260, and P=0.0170; P=0.0240 respectively). Conclusion Previously untreated POAG patients exhibit reduced IOP, increased MOPP and improved ocular perfusion at the ONH and retina levels when treated with Latanoprost 0.005%. These effects could be beneficial for glaucoma patients suffering from ocular vascular dysregulation.

Autonomic dysfunction in unselected and untreated primary open angle glaucoma patients:A pilot study

Purpose: To investigate the presence of silent cardiac ischaemic episodes and the status of autonomic function in consecutive, newly diagnosed and untreated primary open-angle glaucoma patients. Methods: Twenty-four consecutively diagnosed glaucoma patients and 22 age-matched controls were subjected to ambulatory 24-h blood pressure (BP) and electrocardiogram (ECG) monitoring by using Cardiotens-01 (Meditech Ltd). Based on the ECG recordings, heart rate variability (HRV) frequency domain parameters [low-frequency (LF), high-frequency (HF) and LF/HF ratio] were calculated and analysed in the two study groups. Results: Glaucoma patients demonstrated higher LF and LF/HF values than normal subjects for both the active period (p = 0.020 and 0.029) and the passive period (p = 0.044 and 0.049 respectively). HRV parameters were similar in patients and controls suffering from silent cardiac ischaemia (p > 0.05); however, glaucoma patients with normal ECG demonstrated higher LF and LF/HF values during the active period of the 24-h measurement period than control subjects characterized by the same cardiac activity (p = 0.010 and 0.021 respectively). Conclusion: Independent of a history and/or clinical signs of cardiovascular disease, glaucoma patients exhibit abnormal autonomic function. © 2007 The Authors.

Relationship between ocular perfusion pressure and retrobulbar blood flow in patients with glaucoma with progressive damage

PURPOSE: To evaluate the relationship between ocular perfusion pressure and color Doppler measurements in patients with glaucoma. MATERIALS AND METHODS: Twenty patients with primary open-angle glaucoma with visual field deterioration in spite of an intraocular pressure lowered below 21 mm Hg, 20 age-matched patients with glaucoma with stable visual fields, and 20 age-matched healthy controls were recruited. After a 20-minute rest in a supine position, intraocular pressure and color Doppler measurements parameters of the ophthalmic artery and the central retinal artery were obtained. Correlations between mean ocular perfusion pressure and color Doppler measurements parameters were determined. RESULTS: Patients with glaucoma showed a higher intraocular pressure (P <.0008) and a lower mean ocular perfusion pressure (P <.0045) compared with healthy subjects. Patients with deteriorating glaucoma showed a lower mean blood pressure (P =.033) and a lower end diastolic velocity in the central retinal artery (P =.0093) compared with normals. Mean ocular perfusion pressure correlated positively with end diastolic velocity in the ophthalmic artery (R = 0.66, P =.002) and central retinal artery (R = 0.74, P <.0001) and negatively with resistivity index in the ophthalmic artery (R = -0.70, P =.001) and central retinal artery (R = -0.62, P =.003) in patients with deteriorating glaucoma. Such correlations did not occur in patients with glaucoma with stable visual fields or in normal subjects. The correlations were statistically significantly different between the study groups (parallelism of regression lines in an analysis of covariance model) for end diastolic velocity (P =.001) and resistivity index (P =.0001) in the ophthalmic artery, as well as for end diastolic velocity (P =.0009) and resistivity index (P =. 001) in the central retinal artery. CONCLUSIONS: The present findings suggest that alterations in ocular blood flow regulation may contribute to the progression in glaucomatous damage.

The genetics of glaucoma

The present article reviews the patterns of inheritance associated with glaucoma, how the genes linked to the disease have been located and identified, and considers how the effect of some of these genes could lead to glaucoma.

The genetics of primary congenital glaucoma

One of the objectives of the molecular biological study of glaucoma is to establish how the disease develops as a result of the production of aberrant gene products. Many of the genes associated with glaucoma code for proteins which are likely to be directly or indirectly involved in the development and/or function of cells within the trabecular meshwork. The identification of specific defects in these genes is likely to lead to a better understanding of the mechanisms involved in PCG and glaucoma in general and to the development of alternative therapies to surgery. The CYP1B1 gene in particular, which is a linked to congenital glaucoma, and is expressed in the trabecular meshwork, codes for a member of the cytochrome P450 group of proteins. These iron binding proteins constitute a family of enzymes involved in the processes of xenobiotic metabolism, growth, and development. The discovery of the CYP1B1 gene in PCG emphases the importance of abnormalities in the molecular structure of proteins expressed in cells of the trabecular network as a cause of PCG. The identification of specific genetic defects leads to the possibility of more widespread screening for PCG especially in affected families and hence, the possibility of the identification of asymptomatic carriers of the disease. Early identification of 'at risk' parents may then enable earlier detection of PCG and intervention in the infant.

The genetics of glaucoma

This article reviews the patterns of inheritance associated with glaucoma, how the genes linked to glaucoma have been located and identified and considers how the effect of some of these genes could lead to glaucoma.

Structure and function in primary open angle glaucoma

The study utilised a Normal group, an Ocular Hypertensive (OHT) group and a Primary Open Angle Glaucoma (POAG) group to investigate two aspects. Firstly, the within- and between-visit variability for stereometric measurements of the optic nerve head (ONH) using the Heidelberg Retina Tomograph (HRT); retinal nerve fibre layer (RNFL) thickness using the HRT and using optical coherence tomography with the Optical Coherence Tomography Scanner (OCT); the visual field using white-on-white (W-W), short-wavelength (SWAP) and Frequency Doubling perimetry (FDT); and retinal haemodynamics using the Heidelberg Retinal Flowmeter (HRF). Secondly, the association demonstrated between some of the derived variables. The within- and between-visit variability for stereometric measurements of the entire ONH and the between-visit variability for sectoral measurements were similar for Normals and OHTs but greater for POAGs. The within-visit variability of the visual field pointwise parameters for SWAP were greater than for W-W and FDT particularly with increase in eccentricity and for the OHT group. The between-visit variability increased with increase in defect depth for the POAG group, across all types of perimetry. The MS was greater, the MD and PSD smaller and the examination duration shorter in FDT compared to W-W and SWAP across all groups. The within-visit variability was less than the between-visit variability for the OCT circumferential and sector RNFL thickness using the 1.5R, 2.0R and the fixed 1.73mm circular scan radii, across the three groups. The variability increased with decrease in the RNFL thickness, and was least for the 2.0R scan radius.

Variability of the permetric response in normals and in glaucoma

This study investigated the variability of response associated with various perimetric techniques, with the aim of improving the clinical interpretation of automated static threshold perirnetry. Evaluation of a third generation of perimetric threshold algorithms (SITA) demonstrated a reduction in test duration by approximately 50% both in normal subjects and in glaucoma patients. SITA produced a slightly higher, but clinically insignificant, Mean Sensitivity than with the previous generations of algorithms. This was associated with a decreased between-subject variability in sensitivity and hence, lower confidence intervals for normality. In glaucoma, the SITA algorithms gave rise to more statistically significant visual field defects and a similar between-visit repeatability to the Full Threshold and FASTPAC algorithms. The higher estimated sensitivity observed with SITA compared to Full Threshold and FASTPAC were not attributed to a reduction in the fatigue effect. The investigation of a novel method of maintaining patient fixation, a roving fixation target which paused immediately prior lo the stimulus presentation, revealed a greater degree of fixational instability with the roving fixation target compared to the conventional static fixation target. Previous experience with traditional white-white perimetry did not eradicate the learning effect in short-wavelength automated perimetry (SWAP) in a group of ocular hypertensive patients. The learning effect was smaller in an experienced group of patients compared to a naive group of patients, but was still at a significant level to require that patients should undertake a series of at least three familiarisation tests with SWAP.

Reduction in blood glutathione levels occurs similarly in patients with primary-open angle or normal tension glaucoma

PURPOSE. To investigate in parallel the systemic glutathione levels of patients suffering from primary open angle glaucoma (POAG) or normal tension glaucoma (NTG) with comparable functional loss. METHODS. Thirty-four POAG patients, 30 NTG patients, and 53 controls were subjected to blood analysis to detect the level of circulating glutathione in its reduced (GSH) and oxidized (GSSG) forms. Systemic blood pressure (BP) and ocular perfusion pressure (OPP) parameters were also determined. RESULTS. Independent of age, POAG and NTG patients demonstrated significantly lower GSH and t-GSH levels than age-matched controls (P < 0.001). Additionally, a lower redox index was found, but in POAG patients only, in comparison to both NTG and control groups (P = 0.020). GSSG levels were, however, similar between all study groups (P > 0.05). CONCLUSIONS. This study demonstrates, for the first time, that both POAG and NTG patients exhibit lower GSH and t-GSH levels than age-matched controls, indicating a similar general compromise of the antioxidant defense systems may exist in both conditions. © 2013 The Association for Research in Vision and Ophthalmology, Inc.

The relationship between measurement method and corneal structure on apparent intraocular pressure in glaucoma and ocular hypertension

Purpose: To analyse the relationship between measured intraocular pressure (IOP) and central corneal thickness (CCT), corneal hysteresis (CH) and corneal resistance factor (CRF) in ocular hypertension (OHT), primary open-angle (POAG) and normal tension glaucoma (NTG) eyes using multiple tonometry devices. Methods: Right eyes of patients diagnosed with OHT (n=47), normal tension glaucoma (n=17) and POAG (n=50) were assessed, IOP was measured in random order with four devices: Goldmann applanation tonometry (GAT); Pascal(R) dynamic contour tonometer (DCT); Reichert(R) ocular response analyser (ORA); and Tono-Pen(R) XL. CCT was then measured using a hand-held ultrasonic pachymeter. CH and CRF were derived from the air pressure to corneal reflectance relationship of the ORA data. Results: Compared to the GAT, the Tonopen and ORA Goldmann equivalent (IOPg) and corneal compensated (IOPcc) measured higher IOP readings (F=19.351, p<0.001), particularly in NTG (F=12.604, p<0.001). DCT was closest to Goldmann IOP and had the lowest variance. CCT was significantly different (F=8.305, p<0.001) between the 3 conditions as was CH (F=6.854, p=0.002) and CRF (F=19.653, p<0.001). IOPcc measures were not affected by CCT. The DCT was generally not affected by corneal biomechanical factors. Conclusion: This study suggests that as the true pressure of the eye cannot be determined non-invasively, measurements from any tonometer should be interpreted with care, particularly when alterations in the corneal tissue are suspected.