Prevention of visual field defect progression with brovincamine in eyes with normal-tension glaucoma

The Role of Retinal Ganglion Cell Structure and Function in Glaucoma

Glaucoma, a leading cause of irreversible blindness globally, primarily affects retinal ganglion cells (RGCs). This review dives into the anatomy of RGC subtypes, covering the different underlying theoretical mechanisms that lead to RGC susceptibility in glaucoma, including mechanical, vascular, excitotoxicity, and neurotrophic factor deficiency, as well as oxidative stress and inflammation. Furthermore, we examined numerous imaging methods and functional assessments to gain insight into RGC health. Finally, we investigated the current possible neuroprotective targets for RGCs that could help with future glaucoma research and management.

A Systematic Review and Meta-analysis of Systemic Antihypertensive Medications With Intraocular Pressure and Glaucoma

PURPOSE

We synthesized the literature on the association between systemic antihypertensive medications with intraocular pressure (IOP) and glaucoma. Antihypertensive medications included β-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and diuretics.

DESIGN

Systematic review and meta-analysis.

METHODS

Databases were searched for relevant articles until December 5, 2022. Studies were eligible if they examined (1) the association between systemic antihypertensive medications with glaucoma or (2) the association between systemic antihypertensive medications with IOP in those without glaucoma or ocular hypertension. The protocol was registered at PROSPERO (International Prospective Register of Systematic Reviews; registration ID: CRD42022352028).

RESULTS

A total of 11 studies were included in the review and 10 studies in the meta-analysis. The 3 studies on IOP were cross-sectional, whereas the 8 studies on glaucoma were primarily longitudinal. In the meta-analysis, β-blockers were associated with a lower odds of glaucoma (odds ratio: 0.83, 95% CI: 0.75-0.92, 7 studies, n = 219,535) and lower IOP (β: -0.53, 95% CI: -1.05 to -0.02, 3 studies, n = 28,683). Calcium channel blockers were associated with a higher odds of glaucoma (odds ratio: 1.13, 95% CI: 1.03-1.24, 7 studies, n = 219,535) but not with IOP (β: -0.11, 95% CI: -0.25 to 0.03, 2 studies, n = 20,620). There were no consistent associations between angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or diuretics with glaucoma or IOP.

CONCLUSIONS

Systemic antihypertensive medications have heterogeneous effects on glaucoma and IOP. Clinicians should be aware that systemic antihypertensive medications may mask elevated IOP or positively or negatively affect the risk of glaucoma.

Neuroprotective effect of the calcium channel blocker nilvadipine on retinal ganglion cell death in a mouse ocular hypertension model

We investigated whether nilvadipine has a neuroprotective effect on retinal ganglion cells (RGCs) in a mouse model of ocular hypertension (OH) that expresses cyan fluorescein protein (CFP) in RGCs. OH was induced in the right eyes of Thy1-CFP transgenic mice using a laser. Nilvadipine or vehicle treatment began simultaneously with OH modeling and was administered intraperitoneally once daily for 8 weeks. Intraocular pressure (IOP) in both the laser- and non-treated eyes was measured weekly with the microneedle method, and calculations were performed to estimate the pressure insult in each eye. Using a retinal whole mount, the number of RGCs was counted at week 9. Laser-treated eyes showed a significant increase in IOP (p < 0.01), and the pressure insult did not differ between the drug-treated groups. Over time, laser treatment produced a significant decrease in the number of RGCs in the vehicle-treated groups, but this effect was attenuated by nilvadipine treatment. The pressure insult and RGC survival rate were significantly negatively correlated in the vehicle-treated group (y = -0.078 x + 107.8, r = 0.76, p < 0.001), but not in the nilvadipine-treated group (y = -0.015 x + 99.9, r = 0.43, p = 0.128). Nilvadipine was a potent neuroprotective agent for RGCs in our mouse model of OH and may have potential for protection against glaucoma. This model is useful as a screening tool for drugs with retinal protective effects.

The Japan Glaucoma Society guidelines for glaucoma 5th edition

We are pleased to bring you the 5th edition of the Glaucoma Clinical Practice Guidelines. Clinical practice guidelines are based on evidence (scientific grounds). It is a document that presents the treatment that is the most appropriate for the patient. "Glaucoma Clinical Guidelines" was first published in 2003. This was the first guideline for glaucoma treatment in Japan. The principle of glaucoma treatment is to lower intraocular pressure. Means for lowering intraocular pressure includes drugs, lasers, and surgery; Glaucoma is a disease that should be considered as a complex syndrome rather than a single condition. Therefore, the actual medical treatment is not as simple as one word. This time we set the Clinical Questionnaire with a focus on glaucoma treatment. We hope that you will take advantage of the 5th edition.

The natural history of untreated ocular hypertension and glaucoma

Glaucoma is a chronic, progressive disease leading to irreversible blindness if left untreated; however, since reducing intraocular pressure has proven to be successful in slowing disease progression, little is known about the natural history of untreated glaucoma. This knowledge can be valuable in guiding management decisions in the era of personalized medicine. A systematic search was performed in Medline (PubMed), Embase, and Web of Science in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRIMSA) guidelines. The rate of structural and/or functional progression and conversion to glaucoma or to a more advanced stage of glaucoma are discussed for ocular hypertension and different types of open-angle glaucoma. Forty-three studies were included. Different rates of progression were found both among and within the different diagnostic groups that belong to the open-angle glaucoma spectrum. The highest rate was found in pseudoexfoliation glaucoma, followed by high tension glaucoma, normal tension glaucoma, and ocular hypertension, in decreasing order. The lowest rate was observed in glaucoma suspects. The known rates of progression provide valuable prognostic information for ophthalmologists and patients. Nonetheless, due to high variability among patients, individual progression cannot be accurately predicted and repeated follow-up examinations are required to estimate individual progression.

Neuroprotection in Glaucoma: Basic Aspects and Clinical Relevance

Glaucoma is a neurodegenerative disease that affects primarily the retinal ganglion cells (RGCs). Increased intraocular pressure (IOP) is one of the major risk factors for glaucoma. The mainstay of current glaucoma therapy is limited to lowering IOP; however, controlling IOP in certain patients can be futile in slowing disease progression. The understanding of potential biomolecular processes that occur in glaucomatous degeneration allows for the development of glaucoma treatments that modulate the death of RGCs. Neuroprotection is the modification of RGCs and the microenvironment of neurons to promote neuron survival and function. Numerous studies have revealed effective neuroprotection modalities in animal models of glaucoma; nevertheless, clinical translation remains a major challenge. In this review, we select the most clinically relevant treatment strategies, summarize preclinical and clinical data as well as recent therapeutic advances in IOP-independent neuroprotection research, and discuss the feasibility and hurdles of each therapeutic approach based on possible pathogenic mechanisms. We also summarize the potential therapeutic mechanisms of various agents in neuroprotection related to glutamate excitotoxicity.

Multiple Systemic Vascular Risk Factors Are Associated With Low-Tension Glaucoma

PRCIS

Multiple systemic vascular-associated conditions including systemic hypertension and hypotension, diabetes mellitus, migraine headache, peripheral vascular disease, Raynaud syndrome, and anemia were associated with low-tension glaucoma.

PURPOSE

The purpose of this study was to identify systemic risk factors associated with low-tension glaucoma.

PATIENTS AND METHODS

A retrospective case-control study design was employed to identify patients seen at the Mayo Clinic Department of Ophthalmology between 2005 and 2015 with low-tension glaucoma and an age-matched and sex-matched control group, each containing 277 patients.

RESULTS

The low-tension glaucoma group had more myopic refractive errors (-1.6 vs. -1.0 D, P<0.001), lower intraocular pressure (14.2 vs. 15.2 mm Hg, P<0.001), and a higher cup-to-disc ratio (0.7 vs. 0.3, P<0.001). The low-tension glaucoma group was significantly less likely to be obese (body mass index >30, P=0.03). This group had a significantly higher prevalence of systemic hypertension [odds ratio (OR): 1.64, P=0.004], diabetes mellitus (OR: 3.01, P<0.001), peripheral vascular disease (OR: 2.61, P=0.009), migraine headache (OR: 2.12, P=0.02), anemia (OR: 2.18, P=0.003), systemic hypotension (OR: 4.43, P<0.001), Raynaud syndrome (OR: 3.09, P=0.05), and angiotensin-converting enzyme inhibitor (OR: 1.64, P=0.01) or calcium channel blocker use (OR: 1.98, P=0.004). After adjusting for systemic hypertension, calcium channel blocker use remained significant (OR: 1.70, P=0.03). No significant difference was found between groups with respect to hyperlipidemia, obstructive sleep apnea, coronary artery disease, carotid stenosis, stroke, or statin, angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, beta-blocker, or metformin use.

CONCLUSIONS

Multiple vascular-associated conditions were associated with low-tension glaucoma including systemic hypertension, diabetes mellitus, peripheral vascular disease, migraine headache, Raynaud syndrome, anemia, systemic hypotension, and calcium channel blocker use. This study strengthens the evidence for the vascular hypothesis of low-tension glaucoma.

A Review of Potential Novel Glaucoma Therapeutic Options Independent of Intraocular Pressure

Glaucoma, a progressive optic neuropathy characterized by retinal ganglion cell degeneration and visual field loss, is the leading cause of irreversible blindness worldwide. Intraocular pressure (IOP) is presently the only modifiable risk factor demonstrated to slow or halt disease progression; however, glaucomatous damage persists in almost 50% of patients despite significant IOP reduction. Many studies have investigated the non-IOP-related risk factors that contribute to glaucoma progression as well as interventions that can prevent or delay glaucomatous neurodegeneration and preserve vision throughout life, independently of IOP. A vast number of experimental studies have reported effective neuroprotection in glaucoma, and clinical studies are ongoing attempting to provide strong evidence of effectiveness of these interventions. In this review, we look into the current understanding of the pathophysiology of glaucoma and explore the recent advances in non-IOP related strategies for neuroprotection and neuroregeneration in glaucoma.

Efficacy of Vincamine treatment in a rat model of anterior ischemic optic neuropathy

Non-arteritic anterior ischemic optic neuropathy (NAION) is characterized by the progressive and irreversible death of retinal ganglion cells (RGCs) which is caused by the insufficient blood supply to the optic nerve (ON) head. At present, hormone therapy is used to reduce optic edema, followed by nerve nutrition therapy to protect the ON. However, no surgical or medical therapy has proven to be beneficial consistently in treating NAION. Vincamine is an alkaloid extracted from the Apocynaceae Vinca plant. Vincamine and its derivatives acting as cerebral vasodilators can easily cross the blood-brain barrier, improve the metabolism of ischemic tissue and protect the neuron. In this study, we aimed to investigate the potential neuroprotection of Vincamine in the photodynamic induced rat model of NAION (rAION), to evaluate its effects and possible mechanisms. We found that Vincamine can rescue RGC death and reduce the number of apoptotic cells. The protection of Vincamine might play through the PI3K/Akt/eNOS signaling pathway. Therefore, Vincamine can be an effective therapy method for NAION.

Effect of cold provocation on vessel density in eyes with primary open angle glaucoma: An optical coherence tomography angiography study

The cold pressor test (CPT) induces a cardiovascular response, which may affect ocular blood flow and neuronal function. This study assessed whether optical coherence tomography angiography (OCT-A) can be used to evaluate CPT-induced changes in healthy eyes and in eyes with primary open-angle glaucoma (POAG). Twenty-two healthy subjects and 23 subjects with POAG and retinal fibre layer defects in only one hemifield were included in this study. The CPT was performed by submerging a subject’s hand in cold water (0–4 °C) for 1 minute. The results showed that baseline peripapillary and macular vessel density (VD) measurements were significantly lower in subjects with POAG than in controls (all P < 0.05). Post-CPT VD measurements did not significantly differ from baseline in either healthy or glaucomatous eyes. Additionally, CPT-induced changes in VD did not differ among normal eyes, damaged and undamaged glaucomatous hemifields. Changes in VD were also not significantly influenced by self-reported history of cold extremities. In conclusion, the CPT does not induce significant VD changes, as measured by OCT-A, in the peripapillary or macular areas of either healthy eyes or eyes with POAG. The VD, an all-or-nothing flow measure, may not be sensitive enough for evaluating cold-induced ocular haemodynamic changes.

An Artificial Intelligence Approach to Detect Visual Field Progression in Glaucoma Based on Spatial Pattern Analysis

Purpose

To detect visual field (VF) progression by analyzing spatial pattern changes.

Methods

We selected 12,217 eyes from 7360 patients with at least five reliable 24-2 VFs and 5 years of follow-up with an interval of at least 6 months. VFs were decomposed into 16 archetype patterns previously derived by artificial intelligence techniques. Linear regressions were applied to the 16 archetype weights of VF series over time. We defined progression as the decrease rate of the normal archetype or any increase rate of the 15 VF defect archetypes to be outside normal limits. The archetype method was compared with mean deviation (MD) slope, Advanced Glaucoma Intervention Study (AGIS) scoring, Collaborative Initial Glaucoma Treatment Study (CIGTS) scoring, and the permutation of pointwise linear regression (PoPLR), and was validated by a subset of VFs assessed by three glaucoma specialists.

Results

In the method development cohort of 11,817 eyes, the archetype method agreed more with MD slope (kappa: 0.37) and PoPLR (0.33) than AGIS (0.12) and CIGTS (0.22). The most frequently progressed patterns included decreased normal pattern (63.7%), and increased nasal steps (16.4%), altitudinal loss (15.9%), superior-peripheral defect (12.1%), paracentral/central defects (10.5%), and near total loss (10.4%). In the clinical validation cohort of 397 eyes with 27.5% of confirmed progression, the agreement (kappa) and accuracy (mean of hit rate and correct rejection rate) of the archetype method (0.51 and 0.77) significantly (P < 0.001 for all) outperformed AGIS (0.06 and 0.52), CIGTS (0.24 and 0.59), MD slope (0.21 and 0.59), and PoPLR (0.26 and 0.60).

Conclusions

The archetype method can inform clinicians of VF progression patterns.

The Effect of Betaxolol on Ocular Blood Flow and Visual Fields in Patients with Normotension Glaucoma

Purpose

This study investigated the effect of ophthalmic betaxolol, a ß, selective adrenoceptor antagonist, on ocular blood flow and visual function in patients with normotension glaucoma (NTG).

Methods

Thirty-six eyes of eighteen patients with NTG, but otherwise free of systemic disease, were included. Blood fibrinogen, sedimentation rates, Goldmann intraocular pressure, Humphrey automated perimetry, and color Doppler imaging were done at baseline and after one year of twice-daily bilateral topical ocular dosing with 0.5% betaxolol HCl.

Results

After treatment, the resistivity index of the ophthalmic artery was significantly reduced, and visual fields were significantly improved. The resistivity indexes of the central retinal artery and posterior ciliary artery were also reduced but did not achieve statistical significance. Intraocular pressure was significantly reduced. There was no change in blood fibrinogen and sedimentation rates.

Conclusions

These findings indicate that long-term treatment with ophthalmic betaxolol improves ocular hemodynamics by lowering the resistivity index of the ophthalmic artery and results in an improvement in the visual fields of patients with NTG. In view of this positive effect on blood flow and visual function, betaxolol is recommended in the management of patients with NTG.

Neuroprotection for treatment of glaucoma in adults

BACKGROUND

Glaucoma is a heterogeneous group of conditions involving progressive damage to the optic nerve, deterioration of retinal ganglion cells, and ultimately visual field loss. It is a leading cause of blindness worldwide. Open angle glaucoma (OAG), the most common form of glaucoma, is a chronic condition that may or may not present with increased intraocular pressure (IOP). Neuroprotection for glaucoma refers to any intervention intended to prevent optic nerve damage or cell death.

OBJECTIVES

The objective of this review was to systematically examine the evidence regarding the effectiveness of neuroprotective agents for slowing the progression of OAG in adults compared with no neuroprotective agent, placebo, or other glaucoma treatment.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 7), Ovid MEDLINE, Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Ovid MEDLINE Daily (January 1946 to August 2016), Embase (January 1980 to August 2016), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to August 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 16 August 2016.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which topical or oral treatments were used for neuroprotection in adults with OAG. Minimum follow-up time was four years.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed titles and abstracts from the literature searches. We obtained full-text copies of potentially relevant studies and re-evaluated for inclusion. Two review authors independently extracted data related to study characteristics, risk of bias, and outcomes. We identified one trial for this review, thus we performed no meta-analysis. Two studies comparing memantine to placebo are currently awaiting classification until study investigators provide additional study details. We documented reasons for excluding studies from the review.

MAIN RESULTS

We included one multicenter RCT of adults with low-pressure glaucoma (Low-pressure Glaucoma Treatment Study, LoGTS) conducted in the USA. The primary outcome was progression of visual field loss after four years of treatment with either brimonidine or timolol. Of the 190 adults enrolled in the study, the investigators excluded 12 (6.3%) after randomization; 77 participants (40.5%) did not complete four years of follow-up. The rate of attrition was unbalanced between groups with more participants dropping out of the brimonidine group (55%) than the timolol group (29%).Of those remaining in the study at four years, participants assigned to brimonidine showed less progression of visual field loss than participants assigned to timolol (risk ratio (RR) 0.35, 95% confidence interval (CI) 0.14 to 0.86; 101 participants). Because of high risk of attrition bias and potential selective outcome reporting, we graded the certainty of evidence for this outcome as very low. At the four-year follow-up, the mean IOP was similar in both groups among those for whom data were available (mean difference 0.20 mmHg, 95% CI -0.73 to 1.13; 91 participants; very low-certainty evidence). The study authors did not report analyzable data for visual acuity or any data related to vertical cup-disc ratio, quality of life, or economic outcomes. The most frequent adverse event was ocular allergy to the study drug, which affected more participants in the brimonidine group than the timolol group (RR 5.32, 95% CI 1.64 to 17.26; 178 participants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Although the only trial we included in this review found less visual field loss in the brimonidine-treated group, the evidence was of such low certainty that we can draw no conclusions from this finding. Further clinical research is needed to determine whether neuroprotective agents may be beneficial for individuals with OAG. Such research should focus on outcomes important to patients, such as preservation of vision, and how these outcomes relate to cell death and optic nerve damage. As OAG is a chronic, progressive disease with variability in symptoms, RCTs designed to measure the effectiveness of neuroprotective agents require a long-term follow-up of five years or longer to detect clinically meaningful effects.

Update on Normal Tension Glaucoma

Normal tension glaucoma (NTG) is labelled when typical glaucomatous disc changes, visual field defects and open anterior chamber angles are associated with intraocular pressure (IOP) constantly below 21 mmHg. Chronic low vascular perfusion, Raynaud's phenomenon, migraine, nocturnal systemic hypotension and over-treated systemic hypertension are the main causes of normal tension glaucoma. Goldmann applanation tonometry, gonioscopy, slit lamp biomicroscopy, optical coherence tomography and visual field analysis are the main tools of investigation for the diagnosis of NTG. Management follows the same principles of treatment for other chronic glaucomas: To reduce IOP by a substantial amount, sufficient to prevent disabling visual loss. Treatment is generally aimed to lower IOP by 30% from pre-existing levels to 12-14 mmHg. Betaxolol, brimonidine, prostaglandin analogues, trabeculectomy (in refractory cases), systemic calcium channel blockers (such as nifedipine) and 24-hour monitoring of blood pressure are considered in the management of NTG. The present review summarises risk factors, causes, pathogenesis, diagnosis and management of NTG.

Neuroprotection in Glaucoma

Glaucoma is a degenerative optic neuropathy characterized by retinal ganglion cell (RGC) loss and visual field defects. It is known that in some glaucoma patients, death of RGCs continues despite intraocular pressure (IOP) reduction. Neuroprotection in the field of glaucoma is defined as any treatment, independent of IOP reduction, which prevents RGC death. Glutamate antagonists, ginkgo biloba extract, neurotrophic factors, antioxidants, calcium channel blockers, brimonidine, glaucoma medications with blood regulatory effect and nitric oxide synthase inhibitors are among compounds with possible neuroprotective activity in preclinical studies. A few agents (such as brimonidine or memantine) with neuroprotective effects in experimental studies have advanced to clinical trials; however the results of clinical trials for these agents have not been conclusive. Nevertheless, lack of compelling clinical evidence has not prevented the off-label use of some of these compounds in glaucoma practice. Stem cell transplantation has been reported to halt experimental neurodegenerative disease processes in the absence of cell replacement. It has been hypothesized that transplantation of some types of stem cells activates multiple neuroprotective pathways via secretion of various factors. The advantage of this approach is a prolonged and targeted effect. Important concerns in this field include the secretion of unwanted harmful mediators, graft survival issues and tumorigenesis. Neuroprotection in glaucoma, pharmacologically or by stem cell transplantation, is an interesting subject waiting for broad and multidisciplinary collaborative studies to better clarify its role in clinical practice.

Calcium channels and their blockers in intraocular pressure and glaucoma

Several factors besides high intraocular pressure assumed to be associated with the development and progression of glaucoma, and calcium channel blockers (CCBs) have been an anticipated option for glaucoma treatment by improving ocular perfusion and/or exerting neuroprotective effects on retinal ganglion cells with safety established in wide and long-term usage. Decrease in IOP has been reported after topical application of CCBs, however, the effect is much smaller and almost negligible after systemic application. Various CCBs have been reported to increase posterior ocular blood flow in vivo and to exert direct neuroprotection in neurons in vitro. Distribution of the drug at a pharmacologically active concentration in the posterior ocular tissues across the blood-brain barrier or blood-retina barrier, especially in the optic nerve head and retina where the ganglion cells mainly suffer from glaucomatous damage, is essential for clinical treatment of glaucoma. Improved visual functions such as sensitivity in the visual field test have been reported after administration of CCBs, but evidences from the randomized studies have been limited and effects of CCBs on blood flow and direct neuroprotection are hardly distinguished from each other.

Neuroprotection for treatment of glaucoma in adults

BACKGROUND

Glaucoma is a heterogeneous group of conditions involving progressive damage to the optic nerve, deterioration of retinal ganglion cells and ultimately visual field loss. It is a leading cause of blindness worldwide. Open angle glaucoma (OAG), the commonest form of glaucoma, is a chronic condition that may or may not present with increased intraocular pressure (IOP). Neuroprotection for glaucoma refers to any intervention intended to prevent optic nerve damage or cell death.

OBJECTIVES

The objective of this review was to systematically examine the evidence regarding the effectiveness of neuroprotective agents for slowing the progression of OAG in adults.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 9), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE, (January 1950 to October 2012), EMBASE (January 1980 to October 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 16 October 2012.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in which topical or oral treatments were used for neuroprotection in adults with OAG. Minimum follow up time was four years.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed titles and abstracts from the literature searches. Full-text copies of potentially relevant studies were obtained and re-evaluated for inclusion. Two review authors independently extracted data related study characteristics, risk of bias, and outcome data. One trial was identified for this review, thus we performed no meta-analysis. Two studies comparing memantine to placebo are currently awaiting classification until additional study details are provided. We documented reasons for excluding studies from the review.

MAIN RESULTS

We included one multi-center RCT of adults with low-pressure glaucoma (Low-pressure Glaucoma Treatment Study, LoGTS) conducted in the USA. The primary outcome was visual field progression after four years of treatment with either brimonidine or timolol. Of the 190 adults enrolled in the study, 12 (6.3%) were excluded after randomization and 77 (40.5%) did not complete four years of follow up. The rate of attrition was unbalanced between groups with more participants dropping out of the brimonidine group (55%) than the timolol group (29%). Of those remaining in the study at four years, participants assigned to brimonidine showed less visual field progression than participants assigned to timolol (5/45 participants in the brimonidine group compared with 18/56 participants in the timolol group). Since no information was available for the 12 participants excluded from the study, or the 77 participants who dropped out of the study, we cannot draw any conclusions from these results as the participants for whom data are missing may or may not have progressed. The mean IOP was similar in both groups at the four-year follow up among those for whom data were available: 14.2 mmHg (standard deviation (SD) = 1.9) among the 43 participants in the brimonidine group and 14.0 mmHg (SD = 2.6) among the 48 participants in the timolol group. Among the participants who developed progressive visual field loss, IOP reduction of 20% or greater was not significantly different between groups: 4/9 participants in the brimonidine group and 12/31 participants in the timolol group. The study authors did not report data for visual acuity or vertical cup-disc ratio. The most frequent adverse event was ocular allergy to study drug, which occurred more frequently in the brimonidine group (20/99 participants) than the timolol group (3/79 participants).

AUTHORS' CONCLUSIONS

Although neuroprotective agents are intended to act as pharmacological antagonists to prevent cell death, this trial did not provide evidence that they are effective in preventing retinal ganglion cell death, and thus preserving vision in people with OAG. Further clinical research is needed to determine whether neuroprotective agents may be beneficial for individuals with OAG. Such research should focus outcomes important to patients, such as preservation of vision, and how these outcomes relate to cell death and optic nerve damage. Since OAG is a chronic, progressive disease with variability in symptoms, RCTs designed to measure the effectiveness of neuroprotective agents would require long-term follow up (more than four years) in order to detect clinically meaningful effects.

Flash electroretinography and pattern visual evoked potential changes in ocular hypertension patients

Purpose. To evaluate the changes of flash electroretinography (fERG) and pattern visual evoked potentials (pVEP) in ocular hypertension (OHT) patients. Methods. Twenty-five OHT patients and 30 healthy volunteers were enrolled for this cross-sectional study. Opthalmologic examinations, visual field tests, pVEP and fERG were performed. The main outcome measures were the differences between pVEP and fERG parameters. Results. The mean age of OHT patients and volunteers were 57 ± 12.25 years (range 30-65 years), and 53.25 ± 12.0 years (range 30-65 years), respectively. The mean amplitude of the pVEP was statistically lower in the OHT group (P < 0.05). Latency of the two groups was different; however, the difference was not statistically significant (P > 0.05). In fERG of OHT group, there was a significant decrease in the amplitude of the oscillatory potentials (Ops), and a significant delay in latency of rod and cone waves (all P < 0.05). There was no significant change in the flicker fERG waves between the two groups (P > 0.05). Conclusions. Although we found a decrease in Ops amplitude and a prolonged latency in flicker fERG, only the decrease in Ops amplitude was statistically significant between the two groups. The amplitude of Ops wave and amplitude of pVEP may reflect early glaucomatous damage in OHT patients.

An evidence-based review of prognostic factors for glaucomatous visual field progression

PURPOSE

To examine which prognostic factors are associated with glaucomatous visual field progression.

DESIGN

Knowledge of prognostic factors helps clinicians to select patients at risk of glaucomatous visual field progression and intensify their treatment.

METHODS

By consulting relevant databases, we identified 2733 articles published up to September 2010, of which 85 articles investigating prognostic factors for visual field progression in patients with open-angle glaucoma (OAG) were eligible. We summarized results for each factor in tables, noting the direction of the association between the prognostic factor and progression, and the accompanying P value. Four authors, working blind to the factors, independently judged the extent to which a prognostic factor was associated with glaucomatous visual field progression. If there were different associations for normal-tension glaucoma (NTG) studies, they were judged separately. Consensus was reached during group meetings.

MAIN OUTCOME MEASURES

A ranking of all studied prognostic factors for glaucomatous visual field progression according to their likelihood of being prognostic.

RESULTS

A total of 103 different prognostic factors were investigated in 85 articles. The following factors were clearly associated with glaucomatous visual field progression: age, disc hemorrhages (for NTG), baseline visual field loss, baseline intraocular pressure (IOP), and exfoliation syndrome. An association was unlikely for family history of glaucoma, atherosclerosis, systemic hypertension, visual acuity, sex (for NTG), systolic blood pressure, myopic refractive error (for NTG), and Raynaud's phenomenon.

CONCLUSIONS

The factors we found clearly associated with progression could be used in clinical practice and for developing clinical prediction models. For many other factors, further research is necessary.

Retrobulbar hemodynamic effects of nipradilol in normal and normal-tension glaucoma eyes

Purpose. To investigate the effects of nipradilol on retrobulbar hemodynamics. Methods. We investigated normal and normal-tension glaucoma (NTG) eyes. Topical nipradilol (one eye) and placebo eye drops (fellow eye) were instilled for 1 week in volunteers. Nipradilol was also instilled in NTG patients. Ultrasound color Doppler imaging for the posterior vessels was performed before, 2 hr, 1 week (for normal), and at 4 weeks (for NTG). Results. In normal eyes, there were significant decreases in the resistance index (RI) for the temporal short posterior ciliary arteries (PCA) at 2 hr and for the ophthalmic arteries at 1 week. There were no significant changes in the placebo-treated eyes. In the NTG eyes, there was a significant decrease in the RI for the central retinal artery, nasal, and temporal PCA at 2 hr and 4 weeks. Conclusion. Short-term observations found that nipradilol increased the ocular blood flow in normal and NTG eyes.

REVIEW: An approach for neuroprotective therapies of secondary brain damage after excitotoxic retinal injury in mice

BACKGROUND

Many current therapeutic strategies for several eye diseases, such as glaucoma, retinal ischemia, and optic neuropathy, are focused on protection of the retinal ganglion cells (RGCs). In fact, loss of visual field, including irreversible blindness, is caused by RGC damage in these diseases. However, recent evidence suggests that the RGC damage extends to visual center in brain: the visual impairment induced by these diseases may result not only from RGC loss, but also from neuronal degeneration within the visual center in brain.

OBJECTIVE

To protect neurons within the visual center in the brain, as well as retinal treatment, for the prevention of visual disorder in these diseases.

METHODS

Once considered difficult to study the visual center in brain following RGCs loss, because obtaining the human samples that are suitable for the study may be difficult. In addition, the monkey, mainly used as glaucomatous model, is relatively high cost and needs to long experiment-span. Here, we focused on mice, because of their high degree of availability, relatively low cost, and amenability to experimental and genetic manipulation.

CONCLUSION

In this review, we describe time-dependent alterations in the visual center in brain following RGCs loss, and whether some drugs prevent the neuronal damage of the visual center in the brain.

WITHDRAWN: Interventions for normal tension glaucoma

BACKGROUND

Normal tension glaucoma is a clinical condition in which the optic nerve is pathologically excavated and the visual field is disturbed. Nevertheless it has been assumed that intraocular pressure plays a role in the progression of visual field defects in this disease, but other, mainly vascular factors, have been discussed as well.

OBJECTIVES

The objective of this review is to assess the effects of medical and surgical treatments for normal tension glaucoma.

SEARCH STRATEGY

Trials were identified from the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group trials register), MEDLINE, EMBASE and BIOSIS Previews. Bibliographies of identified trials were searched to find additional trials. In addition, investigators and pharmaceutical companies were contacted. Date of last search: January 2001.

SELECTION CRITERIA

This review includes randomised controlled trials in which medical or surgical interventions were compared to no treatment, placebo or other treatment in people with normal tension glaucoma.

DATA COLLECTION AND ANALYSIS

Data were extracted by two reviewers and results were compared for differences. Discrepancies were resolved by discussion. The heterogeneity of interventions, follow-up periods and outcomes did not allow for statistical combinations of the study results.

MAIN RESULTS

According to the selection criteria on visual field loss, eight studies were included in this review. Only three studies focussed on patient relevant outcomes. In one trial a beneficial effect of lowering intraocular pressure was found, but only if data were corrected for cataract development. In two small studies a beneficial effect on visual field loss of brovincamine, a calcium antagonist was reported.

AUTHORS' CONCLUSIONS

In one study the effect of intraocular pressure lowering on visual field outcome was only significant when data were corrected for cataract development. The results for calcium antagonists are promising, but larger trials have to be performed. Studies that focussed on reduction of intraocular pressure or haemodynamic variables are not necessarily relevant for the outcome in people with normal tension glaucoma.

Neuroprotection for treatment of glaucoma in adults

BACKGROUND

Glaucoma is a heterogeneous group of conditions involving progressive damage to the optic nerve, deterioration of retinal ganglion cells and ultimately visual field loss. It is a leading cause of blindness worldwide. Open angle glaucoma (OAG), the commonest form of glaucoma, is a chronic condition that may or may not present with increased intraocular pressure (IOP). Neuroprotection for glaucoma refers to any intervention intended to prevent optic nerve damage or cell death. The treatment can target extracellular factors such as reducing IOP, or cellular factors derived from the optic nerve itself such as blocking intracellular death signals.

OBJECTIVES

The objective of this review was to systematically examine the evidence regarding the effectiveness of neuroprotective agents, either topical or oral, for slowing the progression of OAG in adults.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library, Issue 4, 2009), MEDLINE (January 1960 to January 2010), EMBASE (January 1980 to January 2010), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2010) and ClinicalTrials.gov (http://clinicaltrials.gov). (5 January 2010). There were no language or date restrictions in the search for trials. The electronic databases were last searched on 5 January 2010.

SELECTION CRITERIA

This review was limited to randomized controlled trials (RCTs) in which topical or oral treatments were used to prevent retinal ganglion cell death. Our population of interest was adults with OAG. As the primary outcome for this review was the proportion of participants who developed any progression of visual field loss at five years post intervention, only trials with at least five years of follow-up were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed titles and abstracts from the literature searches. Full text copies of relevant or potentially relevant studies were obtained and re-evaluated for inclusion. There were no trials identified for this review, thus we performed no data extraction or meta-analysis. Two studies comparing memantine to placebo are currently awaiting classification until additional study details are provided. Reasons for excluding studies from the review were documented.

MAIN RESULTS

In accordance with the selection criteria for inclusion, we identified no studies relevant for this review. The results of short-term trials and other studies are discussed in this review.

AUTHORS' CONCLUSIONS

Although neuroprotective agents are intended to act as pharmacological antagonists to prevent cell death, the evidence that they are effective in preventing retinal ganglion cell death, and thus preserving vision in patients with OAG, has not been demonstrated. Long-term RCTs are needed to determine whether or not neuroprotective agents may be beneficial for individuals with OAG.

Lomerizine, a Ca2+ channel blocker, protects against neuronal degeneration within the visual center of the brain after retinal damage in mice

The purpose of this study was to determine whether lomerizine, a Ca(2+) channel blocker, protects against neuronal degeneration within the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) after the induction of retinal damage by intravitreal injection of N-methyl-D-aspartate (NMDA) in mice. NMDA (20 mM/2 microL) was injected into the vitreous body of the left eye in mice (DAY 0). Lomerizine at 30 mg/kg, p.o. was administered daily from immediately after the injection of NMDA (DAY 0) to 90 days after (DAY 90). To investigate the neuroprotective effects of lomerizine, the retina, dLGN, and SC were examined using histochemistry and immunohistochemistry. Lomerizine reduced the retinal damage induced by NMDA and partially prevented the transsynaptic neuronal degeneration within dLGN and SC on the contralateral side. Moreover, lomerizine reduced the intravitreal NMDA induced decrease in the light-induced expression of c-Fos in the contralateral dLGN (used in this study to evaluate residual vision). These results indicate that lomerizine affords some protection against transsynaptic neuronal degeneration within the visual center of the mouse brain.

Effect of flunarizine, a calcium channel blocker, on intraocular pressure and aqueous humor dynamics in monkeys

PURPOSE

To evaluate the effects of flunarizine, a nonselective calcium channel blocker, on intraocular pressure (IOP) in monkeys with laser-induced unilateral glaucoma and on aqueous humor dynamics in normal monkeys.

METHODS

The IOP was measured before and hourly for 6 hours after single-dose administration of 0.5%, 1%, or 2% flunarizine to the glaucomatous eye of 8 monkeys with unilateral laser-induced glaucoma. In a separate multiple-dose study, 0.5% flunarizine was applied twice daily for 5 consecutive days to the glaucomatous eye of the same 8 monkeys. IOP was measured at untreated baseline, after treatment with vehicle only, and on treatment days 1, 3, and 5. Tonographic outflow facility and fluorophotometric flow rates of aqueous humor were measured in 7 normal monkeys before and after the fifth dose of twice-daily treatment with 0.5% flunarizine.

RESULTS

Unilateral application of 50 microL of 0.5%, 1%, or 2% flunarizine reduced IOP bilaterally. In the treated glaucomatous eyes, flunarizine reduced the IOP for 2, 3, or 5 hours, with a maximum reduction of 2.5+/-0.5 (mean+/-SEM) mm Hg (9%), 3.0+/-0.4 mm Hg (10%), and 5.0+/-0.8 mm Hg (18%) following the 0.5%, 1%, and 2% concentrations, respectively (P<0.01). The maximum reductions in IOP in the contralateral untreated eyes were 1.3+/-0.5 mm Hg, 1.5+/-0.3 mm Hg, and 2.9+/-0.7 mm Hg following the 0.5%, 1%, and 2% concentrations, respectively (P<0.05). Both the magnitude and duration of the ocular hypotensive effect of 0.5% flunarizine were enhanced with twice-daily administration for 5 days. Outflow facility in normal monkey eyes was increased (P<0.05) by 39% in the treated eyes compared with vehicle-treated contralateral eyes and by 41% compared with baseline values, and aqueous humor flow rates were unchanged (P>0.30).

CONCLUSIONS

Flunarizine reduces IOP in a dose-dependent manner when administered to glaucomatous monkey eyes, but also has an ocular hypotensive effect on the contralateral untreated eyes. An increase in tonographic outflow facility seems to account for the IOP reduction in normal monkey eyes.

Phacoviscocanalostomy versus cataract surgery only in patients with coexisting normal-tension glaucoma: midterm outcomes

PURPOSE

To compare the midterm efficacy and safety of phacoviscocanalostomy (viscocanalostomy, phacoemulsification, and intraocular lens [IOL] implantation) and cataract surgery (phacoemulsification and IOL implantation) in patients with normal-tension glaucoma (NTG) and cataract.

SETTING

Sensho-kai Eye Institute, Kyoto, Japan.

METHODS

Thirty-one eyes had phacoviscocanalostomy, and 35 eyes had uncomplicated cataract surgery only. The intraocular pressure (IOP), postoperative antiglaucoma medications, and visual outcomes were compared between groups.

RESULTS

The mean follow-up was 34.9 months+/-19.8 (SD) (range 7 to 78 months). At 36 months, the mean preoperative IOP and postoperative IOP were 17.2+/-1.5 mm Hg and 14.1+/-1.6 mm Hg, respectively, in the phacoviscocanalostomy group and 16.7+/-1.4 mm Hg and 15.6+/-3.4 mm Hg, respectively, in the cataract surgery only group. The differences between groups were significant at all time points (P<.05). The success probabilities of the phacoviscocanalostomy group achieving 20% and 30% IOP reductions with (or without) medications were 78.5% (67.4%) and 35.5% (37.4%) at 24 months and 58.0% (44.2%) and 28.0% (26.6%) at 48 months, which were significantly better than the probabilities in the cataract surgery only group, which were 16.0% (9.5%) and 5.7% (2.9%) at 24 months (P<.001 for each comparison, Kaplan-Meier life-table analysis with log-rank test). Based on the modified Aulhorn-Greve classification, the visual acuity and visual fields did not deteriorate in the phacoviscocanalostomy group; the visual fields deteriorated in 6 eyes in the cataract surgery only group during the follow-up (P=.024).

CONCLUSION

Phacoviscocanalostomy lowered IOP and maintained postoperative visual outcomes; it was safe and effective in elderly patients with coexisting NTG and cataract.

Effect of 2-(6-cyano-1-hexyn-1-yl)adenosine on ocular blood flow in rabbits

Previously, we reported that a relatively selective adenosine A(2A) receptor agonist 2-(6-cyano-1-hexyn-1-yl)adenosine (2-CN-Ado) elicited ocular hypotension in rabbits (Journal of Pharmacological Sciences 2005;97:501-509). In the present study, we investigated the effect of 2-CN-Ado on ocular blood flow in rabbit eyes. An intravitreal injection of 2-CN-Ado increased ocular blood flow, measured by a non-contact laser flowmeter. 2-CN-Ado-induced increase in ocular blood flow was accompanied with the retinal vasodilation. The increase in ocular blood flow was inhibited by an adenosine A(2A) receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine, but not by an adenosine A(2B) receptor antagonist alloxazine or an adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. The repetitive applications of topical 2-CN-Ado twice a day for 7 days produced a persistent increase in ocular blood flow with ocular hypotension. These results suggest that 2-CN-Ado increases the ocular blood flow mainly via adenosine A(2A) receptor, and that the topical application of 2-CN-Ado for several days not only increases the ocular blood flow but also prolong ocular hypotension, indicating that 2-CN-Ado may be a useful lead compound for the treatment of ischemic retinal diseases such as glaucoma.

Therapeutic Strategies for Normal-Tension Glaucoma

Treatment of normal-tension glaucoma has been a subject of debate for several years. Glaucomatous damage cannot be influenced directly, and current treatment modalities in normal-tension glaucoma are aimed at the control of risk factors. Intraocular pressure is a widely accepted risk factor and its reduction can improve the prognosis in normal-tension glaucoma patients. The repeated demonstration of the importance of hemodynamic factors in normal-tension glaucoma has, however, not been paralleled by a comparable progress in the development of therapeutic modalities capable of influencing favorably ocular blood flow. Today, calcium channel blockers seem to be the most promising adjunctive treatment to be considered in patients with glaucomatous optic neuropathy without increased intraocular pressure.

Ocular distribution after topical instillation and potential neuroprotective effect after intravitreal injection of the calcium channel blocker iganipidine

PURPOSE

To investigate the effects of iganidipine, a new calcium antagonist on glutamate agonist-induced retinal damage.

METHODS

Iganidipine was injected with N-methyl-D-aspartate (NMDA) or kainic acid (KA) into the rat vitreous, and the retina was histologically examined. After co-injection with KA, the number of DiI-labeled retinal ganglion cells was also counted. Rabbits received unilateral instillation of 0.03% iganidipine twice daily for 14 days, and the iganidipine level in the posterior retina-choroid was determined by liquid chromatography/mass spectrometry.

RESULTS

Coadministration of iganidipine had no significant effect on NMDA-induced thinning of the inner plexiform layer but partly suppressed KA-induced thinning at final intravitreous concentrations of 10(-8) M or higher, which was confirmed by counting the ganglion cell number. The iganidipine level in the posterior retina-choroid was approximately 6.2 x 10(-7) M in the instilled eye, which was higher than on the contralateral side by 5.2 x 10(-7) M (p = 0.035).

CONCLUSIONS

Iganidipine suppressed KA-induced retinal damage in rats. This suppression was achieved with a lower concentration than that resulting from unilateral instillations of iganidipine in the ipsilateral posterior retina-choroid in rabbits.

Clinical potential of lomerizine, a Ca2+ channel blocker as an anti-glaucoma drug: effects on ocular circulation and retinal neuronal damage

Glaucoma is defined as an optic neuropathy with characteristic changes in the optic nerve head and ultimate loss of visual field. Previous studies have suggested that (a) mechanical damage due to raised intraocular pressure and (b) a compromised tissue circulation in the optic nerve head play significant roles in the development of glaucomatous damage in the optic nerve head. Recently, we found that lomerizine, a new Ca(2+) channel blocker, increased ocular circulation and protected neuronal cells against retinal neurotoxicity both in vitro and in vivo with minimal cardiovascular side effects. We examined the effect of lomerizine on the ocular circulation and compared it with those of other Ca(2+) channel blockers in normal rabbits and in rabbits with an endothelin-1-disturbed circulation in the optic nerve head. In anesthetized rabbits, lomerizine and the other Ca(2+) channel blockers increased the ocular circulation and also inhibited the hypoperfusion induced in optic nerve head tissue by an intravitreous injection of endothelin-1. Whereas the other Ca(2+) channel blockers produced changes in blood pressure and heart rate, the effects of lomerizine on these parameters were slight. In healthy humans, lomerizine increased blood velocity in the optic nerve head, without significantly altering blood pressure or heart rate. Moreover, lomerizine reduced retinal damage in rats both in vitro and in vivo, presumably through a Ca(2+) channel blocking effect via an action that may involve a direct protection of retinal neurons as well as an improvement in the ocular circulation. These results indicate that lomerizine may be useful as a therapeutic drug against ischemic retinal diseases (such as glaucoma and retinal vascular occlusive diseases) that involve a disturbance of the ocular circulation.

[Mechanisms of neuroprotection against glaucoma]

The goal of neuroprotection in glaucoma treatment is to employ agents that prevent or delay apoptosis of retinal ganglion cells (RGC) and facilitate regeneration of already damaged calls. The following contribution discusses the mechanisms of RGC death and current status of neuroprotective in vivo studies and investigations on cell cultures and animal models. Discussions on the etiopathogenesis of PCOAG center on elevated IOP and ocular disorders of vascular function. The mechanisms of axonal damage induced by ischemia are explained and the resultant possible neuroprotective effect mechanisms are discussed (Na(+) or Ca(2+) channel blockers, role of reactive astrocytes). Substitution of axonal survival factors and especially the role of BDNF are described. Glutamate excitotoxicity also plays a role in glaucomatous antegrade RGC death. Relevant questions and possible therapeutic approaches are discussed. The three phases of apoptosis cascade and the key role of mitochondria in the insult-induced apoptosis are considered as well as the still relatively unexplored possibilities of RGC regeneration. Finally, perspectives of neuroprotective treatment of PCOAG are presented.

Effect of nimodipine on ocular blood flow and colour contrast sensitivity in patients with normal tension glaucoma

AIM

To investigate the effects of oral nimodipine on ocular haemodynamic parameters and colour contrast sensitivity in patients with normal tension glaucoma (NTG).

DESIGN

The study was performed in a randomised, placebo controlled, double masked, crossover design.

PARTICIPANTS

Nimodipine (60 mg) or placebo was administered to 14 consecutive NTG patients.

METHODS

The effects or oral nimodipine or placebo on ocular and systemic haemodynamic parameters and colour contrast sensitivity along the tritan axis were studied two hours after administration. Optic nerve head blood flow (ONHBF) and choroidal blood flow (CHBF) were assessed with laser Doppler flowmetry. Ocular fundus pulsation amplitude (FPA) was measured with laser interferometry. Colour contrast sensitivity (CCS) was determined along the tritan colour axis.

MAIN OUTCOME MEASURES

ONHBF, CHBF, FPA, intraocular pressure and CCS were assessed in patients with NTG.

RESULTS

Mean ocular FPA increased by 14% (SD 14%) (p = 0.0008), ONHBF by 18% (SD 16%) (p = 0.0031), and CHBF by 12% (SD 14%) (p<0.001) after administration of nimodipine. Nimodipine also decreased the threshold of colour contrast sensitivity along the tritan colour axis (-14% (SD 12%); p = 0.048). However, individual changes in FPA, ONHBF, or CHBF were not correlated with changes in threshold of CCS along the tritan colour axis.

CONCLUSIONS

The results indicate that nimodipine increases ONH and choroidal blood flow in NTG patients and improves CCS. The latter effect does not, however, seem to be a direct consequence of the blood flow improvement.

The effects of antiglaucoma and systemic medications on ocular blood flow

Based on the body of evidence implicating ocular blood flow disturbances in the pathogenesis of glaucoma, there is great interest in the investigation of the effects of antiglaucoma drugs and systemic medications on the various ocular vascular beds. The primary aim of this article was to review the current data available on the effects of antiglaucoma drugs and systemic medications on ocular blood flow. We performed a literature search in November 2002, which consisted of a textword search in MEDLINE for the years 1968-2002. The results of this review suggest that there is a severe lack of well-designed long-term studies investigating the effects of antiglaucoma and systemic medications on ocular blood flow in glaucomatous patients. However, among the 136 articles dealing with the effect of antiglaucoma drugs on ocular blood flow, only 36 (26.5%) investigated the effects of medications on glaucoma patients. Among these 36 articles, only 3 (8.3%) were long-term studies, and only 16 (44.4%) were double-masked, randomized, prospective trials. Among the 33 articles describing the effects of systemic medications on ocular blood flow, only 11 (33.3%) investigated glaucoma patients, of which only one (9.1%) was a double-masked, randomized, prospective trial. Based on this preliminary data, we would intimate that few antiglaucoma medications have the potential to directly improve ocular blood flow. Unoprostone appears to have a reproducible antiendothelin-1 effect, betaxolol may exert a calcium-channel blocker action, apraclonidine consistently leads to anterior segment vasoconstriction, and carbonic anhydrase inhibitors seem to accelerate the retinal circulation. Longitudinal, prospective, randomized trials are needed to investigate the effects of vasoactive substances with no hypotensive effect on the progression of glaucoma.

Protective effect of nilvadipine against glutamate neurotoxicity in purified retinal ganglion cells

We determined the effect of nilvadipine, a dihydropyridine-type calcium channel blocker, in preventing glutamate neurotoxicity in purified retinal ganglion cells (RGCs). RGCs were purified from dissociated rat retinal cells (postnatal days 6-8), using a modified two-step panning method, and cultured in serum-free medium containing neurotrophic factors and forskolin. RGC survival after exposure to glutamate (25 microM) with nilvadipine or other calcium channel blockers was measured by calcein-acetoxymethyl ester staining after 3 days in culture. Changes in the level of intracellular Ca(2+) ([Ca(2+)](i)) were measured with fura-2 fluorescence. Induction of apoptosis was evaluated using the TDT-dUTP terminal nick-end labeling technique. The neurotoxic effects of low doses of glutamate were blocked by a specific alpha-amino-3-dihydro-5-methylisoxazole-4-propionate-kainate receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione (20 microM). Simultaneous application of nilvadipine (1-100 nM) with glutamate protected against glutamate neurotoxicity in a dose-dependent manner. Calcium-imaging experiments showed that the glutamate-evoked [Ca(2+)](i) increase was significantly blocked by nilvadipine (P<0.001), but not nifedipine and diltiazem, in about 50% of RGCs. In addition, the application of nilvadipine significantly reduced glutamate-induced apoptosis (P<0.001). These findings suggest that nilvadipine may partly inhibit glutamate-induced apoptotic cell death by blocking calcium influx via voltage-dependent calcium channels in purified RGCs.

Effects of the beta1-selective adrenergic antagonist betaxolol on electroretinography in the perfused cat eye

The effects of the beta1-selective adrenergic antagonist betaxolol on electroretinography (ERG) were studied in the isolated and arterially perfused cat eye. Betaxolol increased the perfusion flow rate, significantly at the administrations of more than 50 microM concentrations and induced a dose-related, reversible increase in the amplitudes of both the a-wave and b-wave of ERG. These results suggest that the calcium-channel blocking mechanism of betaxolol has a beneficial influence on ocular blood flow and retinal electrical activity in response to light. As it is known that ERG is a good indicator of the functional integrity of the retina, this indicates that betaxolol could be an ideal drug for treating glaucoma in which ischemia is involved to some extent.

Interventions for normal tension glaucoma

BACKGROUND

Normal tension glaucoma is a clinical condition in which the optic nerve is pathologically excavated and the visual field is disturbed. Nevertheless it has been assumed that intraocular pressure plays a role in the progression of visual field defects in this disease, but other, mainly vascular factors, have been discussed as well.

OBJECTIVES

The objective of this review is to assess the effects of medical and surgical treatments for normal tension glaucoma.

SEARCH STRATEGY

Trials were identified from the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group trials register), MEDLINE, EMBASE and BIOSIS Previews. Bibliographies of identified trials were searched to find additional trials. In addition, investigators and pharmaceutical companies were contacted. Date of last search: January 2001.

SELECTION CRITERIA

This review includes randomised controlled trials in which medical or surgical interventions were compared to no treatment, placebo or other treatment in people with normal tension glaucoma. Two reviewers independently assessed the full text copies of the possibly relevant trials. Trial quality was assessed according to the methods set out in Section 6 of the Cochrane Reviewers' Handbook (Clarke 2000).

DATA COLLECTION AND ANALYSIS

Data were extracted by two reviewers and results were compared for differences. Discrepancies were resolved by discussion. The heterogeneity of interventions, follow-up periods and outcomes did not allow for statistical combinations of the study results.

MAIN RESULTS

According to the selection criteria on visual field loss, eight studies were included in this review. Only three studies focussed on patient relevant outcomes. In one trial a beneficial effect of lowering intraocular pressure was found, but only if data were corrected for cataract development. In two small studies a beneficial effect on visual field loss of brovincamine, a calcium antagonist was reported.

REVIEWER'S CONCLUSIONS

In one study the effect of intraocular pressure lowering on visual field outcome was only significant when data were corrected for cataract development. The results for calcium antagonists are promising, but larger trials have to be performed. Studies that focussed on reduction of intraocular pressure or haemodynamic variables are not necessarily relevant for the outcome in people with normal tension glaucoma.

Medical treatment of normal tension glaucoma

Normal-tension glaucoma was previously thought to be pressure insensitive, as medical treatment hardly reduced intraocular pressure and it did not prevent visual field loss. In the last decade, however, evidence has shown that the treatment of normal-tension glaucoma by lowering intraocular pressure can slow the deterioration of visual fields, hence the glaucomatous process. It was shown that a reduction of IOP of at least 30% is needed to induce a favorable alteration in the course of normal-tension glaucoma. New agents, such as prostaglandin analogs, the alpha(2)-adrenoceptor agonist brimonidine, and carbonic anhydrase inhibitors, have become available and may be of use in the treatment of normal-tension glaucoma. Monotherapy with prostaglandin analogs may meet the target of a reduction of IOP with 30%, but combination therapy will be needed in many cases. Few studies have been performed with brimonidine, travoprost, and bimatoprost, and it is suggested that more attention should be given to studies with these agents, as about 30% of patients with open angles and glaucomatous visual field defects have normal-tension glaucoma. Although neuroprotection is the goal of the future, no hard data are available yet which demonstrate that treatment with these agents will indeed result in preservation of visual fields.

Long-term follow-up of visual field progression after trabeculectomy in progressive normal-tension glaucoma

OBJECTIVE

To evaluate the long-term effects of trabeculectomy on the progression of visual field damage in patients with progressive normal-tension glaucoma (NTG).

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

Twenty-three patients with NTG who had significant progression of visual field damage preoperatively and underwent trabeculectomy using antimetabolites.

METHODS

Visual field testing using the Humphrey Visual Field Analyzer was periodically performed before and for at least 5 years after surgery (mean, 6 years). The time course of the mean deviation (MD) and mean of total deviations (TD(mean)) in four separate subfields, superior and inferior cecocentral and superior and inferior arcuate fields, were analyzed using a linear mixed effects model.

MAIN OUTCOME MEASURES

Intraocular pressure (IOP), preoperative and postoperative regression coefficients of the time course of MD or TD(mean) in the four subfields, corresponding to the rate of progression of visual field damage.

RESULTS

IOP significantly decreased from 16.2 +/- 1.8 mmHg preoperatively to approximately 11 mmHg during the postoperative follow-up period (P < 0.001). The preoperative regression coefficient of MD change was significantly negative (-1.05 [95% confidence interval, -1.28 to -0.82] dB/year, P < 0.001). After surgery, it increased significantly to -0.44 (95% confidence interval, -0.64 to -0.24) dB/year (P < 0.001), but the postoperative value was still significantly negative (P < 0.001). In the superior cecocentral, superior and inferior arcuate fields, preoperative regression coefficients of TD(mean) change were significantly negative (P < 0.001) and significantly increased after surgery (P < 0.01). In the inferior cecocentral field, the preoperative regression coefficient was not significantly different from 0 (P = 0.72) and did not change significantly after surgery (P = 0.15).

CONCLUSIONS

Trabeculectomy was statistically associated with slowing further progression of visual field damage in patients with progressive NTG. The progression, however, did not completely stop over the 6-year postoperative follow-up period.

Blood flow in the optic nerve head and factors that may influence it

In the recent past there has been great interest in the blood supply of the optic nerve head (ONH), how to evaluate ONH blood flow, and what factors influence it, in health and disease. This is because evidence has progressively accumulated that there is vascular insufficiency in the ONH in both anterior ischemic optic neuropathy (AION) and glaucomatous optic neuropathy (GON)-two major causes of blindness or of seriously impaired vision in man. For the management and prevention of visual loss in these two disorders, a proper understanding of the factors that influence the blood flow in the ONH is essential. The objective of this paper is, therefore, to review and discuss all these factors. The various factors that influence the vascular resistance, mean blood pressure and intraocular pressure are discussed, to create a better basic understanding of the ONH blood flow, which may help us toward a logical strategy for prevention and management of ischemic disorders of the ONH.

Effects of lomerizine, a novel Ca2+ channel blocker, on the normal and endothelin-1-disturbed circulation in the optic nerve head of rabbits

We examined the effects of lomerizine, a new diphenylmethylpiperazine Ca2+ channel blocker, on the normal circulation in the optic nerve head and long posterior ciliary artery, and on endothelin-1-induced hypoperfusion in the optic nerve head in anesthetized rabbits using a hydrogen gas clearance method and laser Doppler flowmetry. These effects were compared with those of nilvadipine and pranidipine. Lomerizine (0.1 and 0.3 mg/kg, i.v.) significantly increased tissue blood flow in the optic nerve head and the putative blood flow in the long posterior ciliary artery with smaller reduction of blood pressure (0.3 mg/kg, i.v.) and without change in heart rate. On the other hand, nilvadipine (0.003 and 0.01 mg/kg, i.v.) and pranidipine (0.003 and 0.01 mg/kg, iv.) each significantly increased blood flow and lowered blood pressure. Moreover, lomerizine (0.1 and 0.3 mg/kg, i.v.) and nilvadipine (0.01 mg/kg, i.v.), when administered 5 min before an endothelin-1 injection (10(-6) M, 100 microl), inhibited the hypoperfusion in the optic nerve head. These results suggest that lomerizine improves the ocular circulation with minimal cardiovascular side effects. Therefore, lomerizine may have clinical potential for the treatment of eye diseases associated with local circulatory disturbances, such as normal-tension glaucoma.

Normal tension glaucoma and primary open angle glaucoma associated with increased platelet aggregation

On purpose of the present study was to evaluate platelet aggregation and fibrinolytic systems in patients with normal tension glaucoma (NTG) or primary open angle glaucoma (POAG). For platelet aggregation, we photoelectrophotometrically investigated adenosine diphosphate (ADP) or collagen-induced platelet aggregation in consecutively selected patients with glaucoma (22 patients with NTG and 13 patients with POAG) and 42 glaucoma free control subjects with normal ocular findings. The aggregation patterns of the patients' platelets reacted abnormally to ADP 1 microM or collagen 0.5 microg/ml as evidenced by secondary aggregation were compared with those of control subjects. For blood coagulative and fibrinolytic systems, we measured prothrombin time, activated partial thromboplastin time, fibrinogen, thrombin-antithrombin III complex (TAT), alpha2 plasmin inhibitor-plasmin complex. Seventeen of 22 patients (77%) with NTG and 5 of 13 patients (38%) with POAG showed abnormal secondary aggregation. A significant difference was observed between the two groups. No control subjects showed abnormal secondary aggregation. In the fibrinolytic test, all the parameters examined showed within normal ranges, although the log10(TAT) value was higher in NTG than in POAG. Results of the present study suggested that increased platelet aggregation as defined by ADP or collagen induced abnormal secondary aggregation in vitro is frequently associated with glaucoma patients and this tendency is more apparent in NTG than that in POAG.

Effect of oral felodipine on ocular circulation

PURPOSE

To evaluate the effects of felodipine, a calcium channel blocker, on ocular circulation.

METHODS

In a double blind, randomized, crossover design, 10 volunteers received placebo or felodipine on 2 separate days. Bidirectional laser Doppler velocimetry (BLDV), laser Doppler flowmetry (LDF), and monochromatic fundus photography (MFP) were employed to assess retinal, choroidal, and optic nerve rim circulatory parameters. Measurements were obtained at baseline, 1.5, and 3 hours after dosing. Blood pressure, intraocular pressure (IOP), and heart rate were monitored, and perfusion pressure (PP) was calculated.

RESULTS

In comparison to placebo, significant average percentage decreases in diastolic blood pressure (BPd; p = 0.001), mean blood pressure (BPm; p = 0.003), and perfusion pressure (PP; p = 0.003) were observed 1.5 hours following felodipine. No significant differences were observed following placebo. Retinal, choroidal and optic nerve rim circulatory parameters showed no significant changes after placebo or felodipine. A significant positive correlation between BPd and optic nerve velocity (ONve1) was observed 3 hours following felodipine (R = +0.654; p = 0.040). In contrast, no significant correlation between BPd and ONve1 was noted (R = +0.198; p = 0.583) following placebo.

CONCLUSIONS

No significant change in retinal, optic nerve rim, or foveolar choroidal blood flow were observed, a factor that may be important in the treatment of systemic hypertension in patients with glaucoma.

Changes in optic nerve head blood flow and retrobular hemodynamics following calcium-channel blocker treatment of normal-tension glaucoma

BACKGROUND

Because calcium channel blockers reduce vascular resistance, they may have a clinical application in the treatment of normal-tension glaucoma (NTG). This study investigates changes in both the optic disc blood flow and the hemodynamics of retrobulbar vessels in NTG patients after the systemic administration of a calcium channel blocker.

METHODS

Twelve eyes of 12 NTG patients (mean age 57.6 +/- 15.3 years) were examined before and after a 4-week treatment with 2 mg b.i.d. oral nilvadipine, an L-typc calcium channel blocker. By scanning laser-Doppler flowmetry (SLDF), we obtained the velocity, flow, and volume from within a 10 x 10 pixel window placed on the temporal rim region of the optic disc perfusion map. By ultrasound color Doppler imaging (CDI), we measured the peak systolic velocity (PSV) and the end diastolic velocity (EDV) of the ophthalmic artery (OA), central retinal artery (CRA), nasal posterior ciliary artery (NPCA), and temporal posterior ciliary artery (TPCA). We then calculated a resistance index (RI) for each vessel.

RESULTS

After treatment, the flow and velocity of the optic disc blood flow significantly increased (P < 0.05). Nilvadipine also significantly reduced RIs of the CRA, NPCA, and TPCA (P < 0.05), and increased both the PSV of the NPCA and the EDVs of the CRA, NPCA, and TPCA. The percent change in velocity correlated significantly with the percent changes of the CRA RI and NPCA RI.

CONCLUSIONS

Oral nilvadipine appears to reduce orbital vascular resistance, which consequently increases the optic disc blood flow.