The Ocular Hypertension Treatment Study: topical medication delays or prevents primary open-angle glaucoma in African American individuals

Social determinants of health and health disparities in glaucoma: A review

Social determinants of health and barriers to care can significantly impact patients' access to glaucoma care and treatment, resulting in disparities within disease presentation, progression, management, and treatment outcomes. The widespread adoption of electronic health record systems has allowed researchers and clinicians to further explore these relationships, identifying factors such as race, ethnicity, and socioeconomic status to be risk factors for more severe disease and lower treatment adherence. These disparities highlight potential targets for interventions to combat these disparities and improve overall patient outcomes. This article provides a summary of the available data on health disparities within glaucoma disease presentation, progression, management, treatment, and outcomes and discusses interventions to improve care delivery and outcomes among patients with glaucoma.

Peroxynitrite-Scavenging Organosilica Nanomedicines for Light-Controllable NO Release and Precision On-Demand Glaucoma Therapy

Nitric oxide (NO) is a promising approach for treating ocular hypertension and glaucoma. However, its clinical application is limited by its uncontrollable release and the unwanted overproduction of peroxynitrite. Herein, a denitrifying hollow mesoporous organosilica nanoparticle (HMMN) with framework cohybridization is first constructed to encapsulate S-nitroso-N-acetyl-d,l-penicillamine (SNAP) to produce SNAP@HMMN with dual capacities of selective peroxynitrite removal and controllable NO release. Featuring a large corneal permeability, the well-designed SNAP@HMMN can achieve trans-corneal delivery to reach the target trabecular meshwork (TM)/Schlemm's canal (SC) site. Upon light irradiation, the intraocular pressure (IOP) is appropriately lowered in an adjustable and long-lasting manner while the outflow tissues are protected from nitrative damage, which is expected to realize precision on-demand glaucoma therapy with little biosafety concern, promising significant clinical translational potential.

Recent advances of smart materials for ocular drug delivery

Owing to the variety and complexity of ocular diseases and the natural ocular barriers, drug therapy for ocular diseases has significant limitations, such as poor drug targeting to the site of the disease, poor drug penetration, and short drug retention time in the vitreous body. With the development of biotechnology, biomedical materials have reached the "smart" stage. To date, despite their inability to overcome all the aforementioned drawbacks, a variety of smart materials have been widely tested to treat various ocular diseases. This review analyses the most recent developments in multiple smart materials (inorganic particles, polymeric particles, lipid-based particles, hydrogels, and devices) to treat common ocular diseases and discusses the future directions and perspectives regarding clinical translation issues. This review can help researchers rationally design more smart materials for specific ocular applications.

Anti-apoptotic and autophagic effect: Using conditioned medium from human bone marrow mesenchymal stem cells to treat human trabecular meshwork cells

Introduction

Glaucoma is a vision-threatening disease associated with accelerated aging of trabecular meshwork (TM) which results in elevated intraocular pressure (IOP). Increased oxidative stress in TM plays an important role in cellular molecular damage which leads to senescence. Autophagy is an intracellular lysosomal degradation process which is activated when cells are under stressful condition, and emerging studies have demonstrated increased expression of modulators of apoptosis and expression of autophagic cascade in ex-vivo TM specimens or cultured TM cells under oxidative stress. Recently, studies have shown neuroprotective and IOP-lowering effects after transplanting mesenchymal stem cells (MSCs) or injecting condition medium (CM) of MSCs into ocular hypertension animal models. However, knowledge of the underlying mechanism accounting for these effects is limited. Using condition medium (CM) from human bone marrow-derived mesenchymal stem cells (BM-MSCs), we investigated the effects of the CM derived from BM-MSCs on TM autophagy and apoptosis.

Methods

H₂O₂ was added to culture medium of human TM cells to mimic oxidative damage in glaucomatous eyes, and the autophagic and anti-apoptotic effects of BM-MSCs-derived CM was explored on the oxidatively damaged cells. Mitochondrial ROS production was examined by MitoSOX™, apoptosis was evaluated using terminal deoxynucleotidyl transferase (dUTP) nick end labeling (TUNEL) staining, and the expression of proteins involved in autophagy as well as extracellular matrix was investigated via Western blot.

Results

There were no significant differences in TM cell viability when the cells were treated with different concentrations of CM in the absence of oxidative stress. Cell viability was significantly higher in oxidatively damaged TM cells treated with 1X or 5X CM compared to untreated TM cells under oxidative stress. The mitochondrial ROS level significantly increased with oxidative stress, which was mitigated in the CM treatment groups. DNA fragmentation significantly decreased in oxidatively stressed TM cells after treatment with CM. LCB3 II/LCB3 I was significantly elevated in the oxidative stress group compared to the control group and was significantly decreased in the CM treatment groups. Expression of fibronectin was not significantly different among the groups.

Conclusion

The CM derived from human BM-MSCs has the capacity to rescue oxidatively damaged human TM cells associated with decreased autophagy and apoptosis. The BM-MSCs CM has potential for slowing down age- and disease-related degeneration of TM in patients with glaucoma, facilitating success in the control of IOP.

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.

Racial Differences in Detection of Glaucoma Using Retinal Nerve Fiber Layer Thickness and Bruch Membrane Opening Minimum Rim Width

PURPOSE

To compare the sensitivities and specificities of the retinal nerve fiber layer thickness (RNFLT) and Bruch membrane opening minimum rim width (BMO-MRW) reference database-based criteria for detection of glaucoma in individuals of European descent (ED) and individuals of African descent (AD).

DESIGN

Comparative diagnostic analysis by race METHODS: 382 eyes of 255 glaucoma patients (ED = 170, AD = 85) and 94 eyes of 50 healthy individuals (ED = 30, AD = 20) with global and sectoral RNFLT and BMO-MRW measured with Spectralis optical coherence tomography (OCT) were included. Six diagnostic criteria were evaluated: global measurement below the 5th or 1st percentile, ≥1 of the 6 sector measurements below the 5th or 1st percentile, and superotemporal (ST) and/or inferotemporal (IT) measurement below the 5th or 1st percentile. The sensitivities and specificities of these measurements for detection of glaucoma were compared using bootstrapping methods.

RESULTS

ST and/or IT RNFLT below the 5th percentile has the best performance for detection of glaucoma among RNFLT classifications with a sensitivity (95% CI) of 89.5% (86.1, 92.5) and specificity of 87.2% (77.8, 95.1). In AD individuals, sensitivities of ST and IT RNFLT and BMO-MRW measurements below the 5th percentile criteria were lower than in ED individuals (RNFLT: 83.7% vs 92.5%, and BMO-MRW: 72.1% vs 88.5%, respectively), as well as specificities (AD RNFLT: 73.7% and BMO-MRW: 89.5% vs ED RNFLT: 96.4% and BMO-MRW: 98.2%, respectively).

CONCLUSIONS

RNFLT and BMO-MRW had consistently lower diagnostic performance in AD individuals compared with ED individuals. BMO-MRW criteria might fail to detect as many as one-third of eyes with glaucoma, specifically in AD individuals. With the current reference database, RNFLT, and especially BMO-MRW, criteria are not adequate for diagnosing glaucoma in AD individuals.

Longitudinal visual field variability and the ability to detect glaucoma progression in black and white individuals

BACKGROUND/AIMS

To investigate racial differences in the variability of longitudinal visual field testing in a 'real-world' clinical population, evaluate how these differences are influenced by socioeconomic status, and estimate the impact of differences in variability on the time to detect visual field progression.

METHODS

This retrospective observational cohort study used data from 1103 eyes from 751 White individuals and 428 eyes from 317 black individuals. Linear regression was performed on the standard automated perimetry mean deviation values for each eye over time. The SD of the residuals from the trend lines was calculated and used as a measure of variability for each eye. The association of race with the SD of the residuals was evaluated using a multivariable generalised estimating equation model with an interaction between race and zip code income. Computer simulations were used to estimate the time to detect visual field progression in the two racial groups.

RESULTS

Black patients had larger visual field variability over time compared with white patients, even when adjusting for zip code level socioeconomic variables (SD of residuals for Black patients=1.53 dB (95% CI 1.43 to 1.64); for white patients=1.26 dB (95% CI 1.14 to 1.22); mean difference: 0.28 (95% CI 0.15 to 0.41); p<0.001). The difference in visual field variability between black and white patients was greater at lower levels of income and led to a delay in detection of glaucoma progression.

CONCLUSION

Black patients had larger visual field variability compared with white patients. This relationship was strongly influenced by socioeconomic status and may partially explain racial disparities in glaucoma outcomes.

Glaucomatous Visual Field Progression in the African Descent and Glaucoma Evaluation Study (ADAGES): Eleven Years of Follow-up

PURPOSE

To compare the rates of visual field (VF) progression between individuals of Black and White race and to investigate whether treatment effects may help explain differences previously reported between racial groups.

DESIGN

Multicenter prospective observational cohort study.

METHODS

Participants were patients in referral tertiary care glaucoma clinics with open angle glaucoma. Eyes were excluded who had <5 VF tests and <2 years of follow-up or any disease that could affect the optic nerve or the VF. The VF mean deviation (MD) slopes over time (dB/y) were calculated with linear regression models. Socioeconomic variables, rates of glaucoma surgery, medications, treated intraocular pressure (IOP), and central corneal thickness (CCT) were investigated.

RESULTS

A total of 516 eyes were included with a mean (95% CI) follow-up time of 11.0 (range, 10.5-11.5) years and 15.0 (range, 14.1-15.8) visits. Participants of Black race were significantly younger (59.7 vs 66.9 years, P < .01) than those of White race. The mean CCT and socioeconomic variables were similar between Black and White groups (P = 0.20 and P = .56, respectively), as were treatment with topical medications (P = .90) and the rate of VF MD change (-0.24 [-0.31 to -0.17] dB/year vs -0.32 [-0.36 to -0.27], P = .11), despite higher treated mean IOP (14.9 [14.5 to 15.4] vs 14.0 [13.6 to 14.4] mm Hg, P = .03) and fewer trabeculectomies (29.5% vs 50.0%, P < .01) in the Black race group.

CONCLUSIONS

Rates of VF progression were similar despite higher treated IOP in the Black race group. Mitigation of health access disparities in this study may have equalized previously reported different rates of VF progression between racial groups.

Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms

Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.

Relationship between mean follow-up intraocular pressure, rates of visual field progression and current target intraocular pressure guidelines

AIMS

To investigate if eyes presenting intraocular pressure (IOP) within the limits of current guideline-driven target IOP indeed experience slow rates of glaucomatous visual field (VF) progression.

METHODS

A total of 8598 24-2 VF tests from 603 eyes from the African Descent and Glaucoma Evaluation Study with manifest glaucoma were included. The sample was split into three groups based on baseline VF mean deviation (MD): G1 (better than -5.0 dB), G2 (-5.0 to -10 dB) and G3 (worse than -10 dB). We investigated the relationship between existing target IOP guidelines and rates of MD progression in these groups.

RESULTS

For stable eyes, the medians and IQR of the mean follow-up IOP were G1=15.0 mmHg (IQR: 13.1 to 17.7), G2=13.2 mmHg (IQR: 11.6 to 14.3) and G3=11.9 mmHg (IQR: 10.1 to 13.8) (p<0.01). When considering the mean follow-up IOP within the limits proposed by current guidelines, the median MD slopes were: -0.20 dB/y (IQR: -0.43 to -0.02) for G1<21 mmHg, -0.19 dB/y (IQR: -0.51 to -0.01) for G2<18 mmHg and -0.15 dB/y (IQR: -0.47 to 0.05) for G3<15 mmHg (p=0.63). There were no significant differences between racial groups.

CONCLUSION

In a sample of patients with manifest glaucoma, despite substantial variability between eyes, adherence to treatment guidelines helped slow the rates of global VF progression at various stages of disease.

TRIAL REGISTRATION NUMBER

clinicaltrials.gov Identifier: NCT00221923.

Glaucoma Screening Using an iPad-Based Visual Field Test in a West African Population

PURPOSE

To investigate the performance of the Melbourne Rapid Fields (MRF) for use in clinic-based visual field testing in a low-resource setting.

DESIGN

Prospective cross-sectional study.

PARTICIPANTS

One hundred and three participants (66 patients with glaucoma and 37 control participants) attending a clinical appointment at the Tema Eye Center, Tema, Ghana.

METHODS

Patients with glaucoma and control participants underwent MRF and Humphrey Field Analyzer (HFA) testing.

MAIN OUTCOME MEASURES

Mean deviation (MD), pattern standard deviation (PSD), reliability parameters, sensitivity, specificity, and area under the receiver operating characteristic curve.

RESULTS

Mean MD was less negative and mean PSD was more positive on the MRF than the HFA in both groups (all P < 0.001). False-positive and false-negative rates were comparable between methods (P = 0.09 and P = 0.35, respectively). In patients with glaucoma, MD and PSD from the 2 devices were correlated strongly (r = 0.84; P < 0.001) and moderately (r = 0.61; P < 0.001), respectively. Agreement analysis revealed that MRF tended to generate significantly higher MD (bias, 3.3 ± 4.1 dB; P = 0.03) and PSD (bias, 1.9 ± 2.8 dB; P = 0.03) with wide limits of agreement. For detecting moderate to advanced glaucoma, the sensitivity was 60.9% for the MRF and 78.3% for the HFA (P = 0.10); respective specificities were 86.5% and 83.8% (P = 0.76).

CONCLUSIONS

The MRF underestimated MD and overestimated PSD values compared with the HFA. Agreement biases were significant, suggesting a weak agreement between the 2 devices. However, the MRF showed potential for screening in a low-resource setting, particularly for detecting moderate to advanced glaucoma.

Endogenous dual stimuli-activated NO generation in the conventional outflow pathway for precision glaucoma therapy

High intraocular pressure (IOP) has been regarded as a predominant risk factor for glaucoma. Nitric oxide (NO) is shown to lower IOP, but the magnitude and duration of IOP reduction are not satisfying due to the poor cornea penetration of NO drugs and limited NO generation in the trabecular meshwork (TM)/Schlemm's canal (SC) area. Herein, we introduce deep cornea penetrating biodegradable hollow mesoporous organosilica (HOS) nanocapsules for the efficient co-delivery of hydrophobic JS-K (J_R) and hydrophilic l-Arginine (L_O). The resulting HOS-J_RL_O can be reduced and oxidized by the ascorbic acid (AA) and catalysis of endothelial nitric oxide synthase (eNOS) in the TM/SC microenvironment to release NO for inducing appreciable IOP reduction in various glaucoma mouse models. In addition to developing an endogenous stimuli-responsive NO nanotherapeutic, this study is also expected to establish a versatile, non-invasive, and efficacious treatment paradigm for precision glaucoma therapy.

The Role of Genetic Ancestry as a Risk Factor for Primary Open-angle Glaucoma in African Americans

Purpose

POAG is the leading cause of irreversible blindness in African Americans. In this study, we quantitatively assess the association of autosomal ancestry with POAG risk in a large cohort of self-identified African Americans.

Methods

Subjects recruited to the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study were classified as glaucoma cases or controls by fellowship-trained glaucoma specialists. POAAGG subjects were genotyped using the MEGA Ex array (discovery cohort, n = 3830; replication cohort, n = 2135). Population structure was interrogated using principal component analysis in the context of the 1000 Genomes Project superpopulations.

Results

The majority of POAAGG samples lie on an axis between African and European superpopulations, with great variation in admixture. Cases had a significantly lower mean value of the ancestral component q0 than controls for both cohorts (P = 6.14-4; P = 3-6), consistent with higher degree of African ancestry. Among POAG cases, higher African ancestry was also associated with thinner central corneal thickness (P = 2-4). Admixture mapping showed that local genetic ancestry was not a significant risk factor for POAG. A polygenic risk score, comprised of 23 glaucoma-associated single nucleotide polymorphisms from the NHGRI-EBI genome-wide association study catalog, was significant in both cohorts (P < 0.001), suggesting that both known POAG single nucleotide polymorphisms and an omnigenic ancestry effect influence POAG risk.

Conclusions

In sum, the POAAGG study population is very admixed, with a higher degree of African ancestry associated with an increased POAG risk. Further analyses should consider social and environmental factors as possible confounding factors for disease predisposition.

Chemo-informatics guided study of natural inhibitors targeting rho GTPase: a lead for treatment of glaucoma

Glaucoma, the most perilous disease leading to blindness is a result of optical neuropathy. Accumulation of aqueous humor in the posterior chamber due to a large difference in the rate of formation and its drainage in the anterior chamber causes an increase in intraocular pressure (IOP) leading to damage of nerve cells. A literature survey has revealed that inhibition of the Rho guanosine triphosphatases (rho GTPase) pathway by specific inhibitors leads to the relaxation of contractile cells involved in the aqueous outflow pathway. Relaxation of the strained contractile cells results in increased outflow thereby releasing IOP. In the present study molecular docking has been used to screen twenty seven bioactive (17 natural compounds and 10 conventional drugs) compounds that may play a significant role in relaxing contractile cells by inhibiting rho-GTPase protein. Docking results showed that among all-natural bioactive compounds Cyanidin and Delphinidine have a good binding affinity (- 8.4 kcal/mol) than the top screened conventional drug molecule Mitomycin, (- 6.3 kcal/mol) when docked with rho-GTPase protein. Cyanidin and Delphinidin belong to anthocyanidin, a glycoside form of anthocyanins from Vaccinium myrtillus L. and Punica granatum. The resembling potential of Cyanidin and Delphinidin concerning the drug Mitomycin was confirmed through simulation analysis. Molecular dynamics study (MDS) for 100 ns, showed that the rho GTPase-Delphinidine complex structure was energetically more stable than rho GTPase-Cyaniding complex in comparison to rho GTPase-Mitomycin complex. The comparative study of both the selected hits (Cyanidin and Delphinidin) was assessed by RMSD, RMSF, Rg, SASA, H-bond, PCA MM/PBSA analysis. The analysis revealed that Delphinidine is more potent to inhibit the rho GTPase as compare to Cyaniding and available conventional drugs in terms of stability and binding free energy. Based on the results, these molecules have good pharmacokinetic and pharmacodynamics properties and will prove to be a promising lead compound as a future drug for Glaucoma.

Selective laser trabeculoplasty versus drops for newly diagnosed ocular hypertension and glaucoma: the LiGHT RCT

BACKGROUND

Newly diagnosed open-angle glaucoma (OAG) and ocular hypertension (OHT) are habitually treated with intraocular pressure (IOP)-lowering eyedrops. Selective laser trabeculoplasty (SLT) is a safe alternative to drops and is rarely used as first-line treatment.

OBJECTIVES

To compare health-related quality of life (HRQoL) in newly diagnosed, treatment-naive patients with OAG or OHT, treated with two treatment pathways: topical IOP-lowering medication from the outset (Medicine-1st) or primary SLT followed by topical medications as required (Laser-1st). We also compared the clinical effectiveness and cost-effectiveness of the two pathways.

DESIGN

A 36-month pragmatic, unmasked, multicentre randomised controlled trial.

SETTINGS

Six collaborating specialist glaucoma clinics across the UK.

PARTICIPANTS

Newly diagnosed patients with OAG or OHT in one or both eyes who were aged ≥ 18 years and able to provide informed consent and read and understand English. Patients needed to qualify for treatment, be able to perform a reliable visual field (VF) test and have visual acuity of at least 6 out of 36 in the study eye. Patients with VF loss mean deviation worse than -12 dB in the better eye or -15 dB in the worse eye were excluded. Patients were also excluded if they had congenital, early childhood or secondary glaucoma or ocular comorbidities; if they had any previous ocular surgery except phacoemulsification, at least 1 year prior to recruitment or any active treatment for ophthalmic conditions; if they were pregnant; or if they were unable to use topical medical therapy or had contraindications to SLT.

INTERVENTIONS

SLT according to a predefined protocol compared with IOP-lowering eyedrops, as per national guidelines.

MAIN OUTCOME MEASURES

The primary outcome was HRQoL at 3 years [as measured using the EuroQol-5 Dimensions, five-level version (EQ-5D-5L) questionnaire]. Secondary outcomes were cost and cost-effectiveness, disease-specific HRQoL, clinical effectiveness and safety.

RESULTS

Of the 718 patients enrolled, 356 were randomised to Laser-1st (initial SLT followed by routine medical treatment) and 362 to Medicine-1st (routine medical treatment only). A total of 652 (91%) patients returned the primary outcome questionnaire at 36 months. The EQ-5D-5L score was not significantly different between the two arms [adjusted mean difference (Laser-1st - Medicine-1st) 0.01, 95% confidence interval (CI) -0.01 to 0.03; p = 0.23] at 36 months. Over 36 months, the proportion of visits at which IOP was within the target range was higher in the Laser-1st arm (93.0%, 95% CI 91.9% to 94.0%) than in the Medicine-1st arm (91.3%, 95% CI 89.9% to 92.5%), with IOP-lowering glaucoma surgery required in 0 and 11 patients, respectively. There was a 97% probability of Laser-1st being more cost-effective than Medicine-1st for the NHS, at a willingness to pay for a quality-adjusted life-year of £20,000, with a reduction in ophthalmology costs of £458 per patient (95% of bootstrap iterations between -£585 and -£345).

LIMITATION

An unmasked design, although a limitation, was essential to capture any treatment effects on patients' perception. The EQ-5D-5L questionnaire is a generic tool used in multiple settings and may not have been the most sensitive tool to investigate HRQoL.

CONCLUSIONS

Compared with medication, SLT provided a stable, drop-free IOP control to 74.2% of patients for at least 3 years, with a reduced need for surgery, lower cost and comparable HRQoL. Based on the evidence, SLT seems to be the most cost-effective first-line treatment option for OAG and OHT, also providing better clinical outcomes.

FUTURE WORK

Longitudinal research into the clinical efficacy of SLT as a first-line treatment will specify the long-term differences of disease progression, treatment intensity and ocular surgery rates between the two pathways.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN32038223.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 31. See the NIHR Journals Library website for further project information.

Glaucoma among the Malaysian Community

Background

According to the WHO, glaucoma is the second leading cause of blindness worldwide. About 50% of the world's glaucoma cases come from the Asian population, and in Malaysia itself, the prevalence of glaucoma is increasing. However, glaucoma is still a foreign word to our community despite the high prevalence. Therefore, there is an urgent need to determine the awareness of glaucoma among the community and its associated factors.

Results

This study showed that only 25.2% of our respondents were aware of glaucoma and it is associated with ethnicity, religion, education, and household income. Besides, among those who were aware, they fall into the group of poor knowledge of glaucoma. On the other hand, the knowledge of glaucoma was associated with occupation and the awareness of glaucoma by definition. The validated questionnaire was distributed and the data were analyzed by SPSS software using t-test, one-way ANOVA, and chi-square test.

Conclusion

Awareness and knowledge of glaucoma in this population is low. These findings suggest that there is a need for an efficient information and education strategy to be designed and conducted to increase the awareness and knowledge of glaucoma so that early detection can be made and effective management of individuals with this condition can be delivered.

Optical measurement of the corneal oscillation for the determination of the intraocular pressure

Motivation

Glaucoma is currently the most common irreversible cause of blindness worldwide. A significant risk factor is an individually increased intraocular pressure (IOP). A precise measurement method is needed to determine the IOP in order to support the diagnosis of the disease and to monitor the outcome of the IOP reduction as a medical intervention. A handheld device is under development with which the patient can perform self-measurements outside the clinical environment.

Method

For the measurement principle of the self-tonometer the eye is acoustically excited to oscillate, which is analyzed and attributed to the present IOP. In order to detect the corneal oscillation, an optical sensor is required which meets the demands of a compact, battery driven self-tonometer. A combination of an infrared diode and a phototransistor provides a high-resolution measurement of the corneal oscillation in the range of 10 μm–150 μm, which is compared to a reference sensor in the context of this study. By means of an angular arrangement of the emitter and the detector, the degree of reflected radiation of the cornea can be increased, allowing a measurement with a high signal-to-noise ratio.

Results

By adjusting the angle of incidence between the detector and the emitter, the signal-to-noise ratio was improved by 40 dB which now allows reasonable measurements of the corneal oscillation. For low amplitudes (10 μm) the signal-to-noise ratio is 10% higher than that of the commercial reference sensor. On the basis of amplitude variations at different IOP levels, the estimated standard uncertainty amounts to <0.5 mm Hg in the physiological pressure range with the proposed measuring approach.

Conclusion

With a compact and cost-effective approach, that suits the requirements for a handheld self-tonometer, the corneal oscillation can be detected with high temporal resolution. The cross-sensitivity of the sensor concept concerning a distance variation can be reduced by adding a distance sensor. Existing systematic influences of corneal biomechanics will be integrated in the sensor concept as a consecutive step.

Diurnal and 24-h Intraocular Pressures in Glaucoma: Monitoring Strategies and Impact on Prognosis and Treatment

The present review casts a critical eye on intraocular pressure (IOP) monitoring and its value in current and future glaucoma care. Crucially, IOP is not fixed, but varies considerably during the 24-h cycle and between one visit and another. Consequently, a single IOP measurement during so-called office hours is insufficient to characterize the real IOP pathology of a patient with glaucoma. To date IOP remains the principal and only modifiable risk factor for the development and progression of glaucoma. Only by evaluating IOP characteristics (mean, peak and fluctuation of IOP) at diagnosis and after IOP-lowering interventions can we appreciate the true efficacy of therapy. Unfortunately, a major limiting factor in glaucoma management is lack of robust IOP data collection. Treatment decisions, advancement of therapy and even surgery are often reached on the basis of limited IOP evidence. Clearly, there is much room to enhance our decision-making and to develop new algorithms for everyday practice. The precise way in which daytime IOP readings can be used as predictors of night-time or 24-h IOP characteristics remains to be determined. In practice it is important to identify those at-risk glaucoma patients for whom a complete 24-h curve is necessary and to distinguish them from those for whom a daytime curve consisting of three IOP measurements (at 10:00, 14:00 and 18:00) would suffice. By employing a staged approach in determining the amount of IOP evidence needed and the rigour required for our monitoring approach for the individual patient, our decisions will be based on more comprehensive data, while at the same time this will optimize use of resources. The patient’s clinical picture should be the main factor that determines which method of IOP monitoring is most appropriate. A diurnal or ideally a 24-h IOP curve will positively impact the management of glaucoma patients who show functional/anatomical progression, despite an apparently acceptable IOP in the clinic. The potential impact of nocturnal IOP elevation remains poorly investigated. The ideal solution in the future is the development of non-invasive methods for obtaining continuous, Goldmann equivalent IOP data on all patients prior to key treatment decisions. Moreover, an important area of future research is to establish the precise relationship between 24-h IOP characteristics and glaucoma progression.

What We Have Learned From the Ocular Hypertension Treatment Study

PURPOSE

To identify results from the Ocular Hypertension Study that can aid patients and clinicians to make evidence-based decisions about the management of ocular hypertension.

DESIGN

Perspective.

RESULTS

At 60 months, the cumulative frequency of developing primary open-angle glaucoma (POAG) was 4.4% in the medication group and 9.5% in the observation group (hazard ratio for medication, 0.40; 95% confidence interval [CI], 0.27-0.59; P < .0001). At 13 years the cumulative proportion of participants who developed POAG was 0.22 (95% CI 0.19-0.25) in the original observation group and 0.16 (95% CI 0.13-0.19) in the original medication group (complementary log-log x²P = .009). A 5-factor model (older age, higher IOP, thinner central corneal thickness, larger cup-to-disc ratio, and higher visual field pattern standard deviation) separated participants at high and low risk of developing POAG.

CONCLUSIONS

Clinicians and patients can make evidence-based decisions about the management of ocular hypertension using the risk model and considering patient age, medical status, life expectancy, and personal preference.

The effect of trabeculectomy surgery on the central visual field in patients with glaucoma using microperimetry and optical coherence tomography

PURPOSE

To determine the functional and structural effects of trabeculectomy surgery on patients with advanced glaucoma and central visual field defects in the early post-operative period.

METHODS

Thirty consecutive adult subjects with advanced glaucoma requiring trabeculectomy surgery and an established visual field defect within 10° of fixation underwent microperimetry (MAIA MP-1, CenterVue, Padova, Italy) and optic disc optical coherence tomography (OCT) imaging (Spectralis, Heidelberg Engineering, Germany) pre-operatively, and 1 month and 3 months following trabeculectomy surgery. Main outcome measures were post-trabeculectomy change in mean threshold on microperimetry and nerve fibre layer thickness on OCT. Fellow eyes were used as controls.

RESULTS

The mean change in MP average threshold values from pre-operative to post-operative was 0.6 ± 1.9 dB for treated eyes and 0.1 ± 1.3 dB for control eyes (p = 0.14) at 1 month and 0.2 ± 2.3 and -0.3 ± 1.6 dB at 3 months (p = 0.22). Mean change in global nerve fibre layer thickness was -0.6 and -0.5 µm for operated and control eyes, respectively (p = 0.83), at 1 month and 0.8 and -0.4 µm at 3 months (p = 0.88). The kappa agreement for structure-function correlation between OCT and MP was 0.735 (confidence interval 0.59-0.88) (p < 0.005).

CONCLUSIONS

Central visual function and retinal nerve fibre layer thickness appear to be preserved in glaucoma patients with central visual field defects undergoing trabeculectomy surgery in the early post-operative period. These data may inform glaucoma surgeons considering trabeculectomy surgery in this patient group.

Reductions in Retrobulbar and Retinal Capillary Blood Flow Strongly Correlate With Changes in Optic Nerve Head and Retinal Morphology Over 4 Years in Open-angle Glaucoma Patients of African Descent Compared With Patients of European Descent

PURPOSE

To investigate the relationship of changes in ocular blood flow with optic nerve head (ONH) and retinal morphology in open-angle glaucoma (OAG) patients of African versus European descent (ED) over 4 years.

MATERIALS AND METHODS

In this study, 112 patients with OAG were examined at baseline, 79 [59 ED, 20 African descent (AD)] of which were followed for 4 years. Retinal capillary blood flow was assessed with Heidelberg retinal flowmetry. Retrobulbar blood flow was measured by color Doppler imaging. Retinal structural changes were examined with optical coherence tomography and Heidelberg retinal tomography-III. Mixed-model analysis of covariance was used to test for the significance of change from baseline to 4-year follow-up, and Pearson correlation coefficients were calculated to evaluate linear associations.

RESULTS

In OAG patients of AD, structural changes of the ONH demonstrated a strong association with the end diastolic velocities and resistive indices of the short posterior ciliary arteries over 4 years. In addition, there was a significantly larger increase in the avascular area of the inferior retina in patients of AD, and this reduction in retinal capillaries strongly correlated with a reduction in macular thickness.

CONCLUSIONS

Reductions in retinal capillary and retrobulbar blood flow strongly correlated with changes in the ONH and macular thickness over 4 years in OAG patients of AD compared with ED. These data suggest that ocular vascular health may be a more influential contributing factor in the pathophysiology of OAG in patients of AD compared with ED.

Diagnostic performance of isolated-check visual evoked potential versus retinal ganglion cell-inner plexiform layer analysis in early primary open-angle glaucoma

Background

The purpose of this study was to compare the diagnostic performance of isolated-check visual evoked potential (icVEP) with that of retinal ganglion cell-inner plexiform layer (GCILP) analysis using optical coherence tomography (OCT).

Methods

A total of 45 patients were enrolled: 25 patients with open-angle glaucoma and 20 healthy patients. All patients underwent a complete ophthalmological examination. Moreover, the OCT examination was used to analyze the structures of the GCIPL. The icVEP technique was used to detect the transmission function of the magnocellular pathway, which is mainly managed by the retinal ganglion cells. The quantitative and qualitative comparisons between the diagnostic power of GCIPL analysis and that of icVEP were performed. The areas under the receiver operating characteristic curves (AUC) of GCIPL analysis and icVEP were compared using the Clarke-Pearson method. The sensitivity and specificity of the two techniques were analyzed and compared using the McNemar test.

Results

With the quantitative comparison, the AUC of icVEP (AUC = 0.892) was higher than that of GCIPL analysis (AUC = 0.814). However, there was no statistical significance between the AUCs of icVEP and GCIPL (P > 0.05). With the qualitative comparison, the sensitivity of icVEP was 80%, and its specificity was 90%. The sensitivity of GCIPL analysis was 72%, and its specificity was 85%. There was no significant difference between the sensitivitiesor specificities of icVEP and GCIPL analysis (P > 0.05). Moreover, 30 (66.67%) eyeshad similar resultsbetween icVEP and GCIPL analysis, and 15 (33.33%) eyes had different results (7 eyes had abnormal results with GCIPL analysisbut normal results with icVEP, and8 eyes had normal results with GCIPL analysisbut abnormal results with icVEP).

Conclusions

The diagnostic power of icVEP was close to that of GCIPL analysis whether the comparison was based on the qualitative or quantitative data.

Comparison of isolated-check visual evoked potential and standard automated perimetry in early glaucoma and high-risk ocular hypertension

AIM

To compare the diagnostic performance of isolated-check visual evoked potential (icVEP) and standard automated perimetry (SAP), for evaluating the application values of icVEP in the detection of early glaucoma.

METHODS

Totally 144 subjects (288 eyes) were enrolled in this study. icVEP testing was performed with the Neucodia visual electrophysiological diagnostic system. A 15% positive-contrast (bright) condition pattern was used in this device to differentiate between glaucoma patients and healthy control subjects. Signal-to-noise ratios (SNR) were derived based on a multivariate statistic. The eyes were judged as abnormal if the test yielded an SNR≤1. SAP testing was performed with the Humphrey Field Analyzer II. The visual fields were deemed as abnormality if the glaucoma hemifield test results outside normal limits; or the pattern standard deviation with P<0.05; or the cluster of three or more non-edge points on the pattern deviation plot in a single hemifield with P<0.05, one of which must have a P<0.01. Disc photographs were graded as either glaucomatous optic neuropathy or normal by two experts who were masked to all other patient information. Moorfields regression analysis (MRA) used as a separate diagnostic classification was performed by Heidelberg retina tomograph (HRT).

RESULTS

When the disc photograph grader was used as diagnostic standard, the sensitivity for SAP and icVEP was 32.3% and 38.5% respectively and specificity was 82.3% and 77.8% respectively. When the MRA Classifier was used as the diagnostic standard, the sensitivity for SAP and icVEP was 48.6% and 51.4% respectively and specificity was 84.1% and 78.0% respectively. When the combined structural assessment was used as the diagnostic standard, the sensitivity for SAP and icVEP was 59.2% and 53.1% respectively and specificity was 84.2% and 84.6% respectivlely. There was no statistical significance between the sensitivity or specificity of SAP and icVEP, regardless of which diagnostic standard was based on.

CONCLUSION

The diagnostic performance of icVEP is not better than that of SAP in the detection of early glaucoma.

Role of the Rho GTPase/Rho kinase signaling pathway in pathogenesis and treatment of glaucoma: Bench to bedside research

Glaucoma is a leading cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP) is considered to be a predominant risk factor for primary open angle glaucoma, the most prevalent form of glaucoma. Although the etiological mechanisms responsible for increased IOP are not completely clear, impairment in aqueous humor (AH) drainage through the conventional or trabecular pathway is recognized to be a primary cause in glaucoma patients. Importantly, lowering of IOP has been demonstrated to reduce progression of vision loss and is a mainstay of treatment for all types of glaucoma. Currently however, there are limited therapeutic options available for lowering IOP especially as it relates to enhancement of AH outflow through the trabecular pathway. Towards addressing this challenge, bench and bedside research conducted over the course of the last decade and a half has identified the significance of inhibiting Rho kinase for lowering IOP. Rho kinase is a downstream effector of Rho GTPase signaling that regulates actomyosin dynamics in numerous cell types. Studies from several laboratories have demonstrated that inhibition of Rho kinase lowers IOP via relaxation of the trabecular meshwork which enhances AH outflow. By contrast, activation of Rho GTPase/Rho kinase signaling in the trabecular outflow pathway increases IOP by altering the contractile, cell adhesive and permeability barrier characteristics of the trabecular meshwork and Schlemm's canal tissues, and by influencing extracellular matrix production and fibrotic activity. This article, written in honor of the late David Epstein, MD, summarizes findings from both basic and clinical studies that have been instrumental for recognition of the importance of the Rho/Rho kinase signaling pathway in regulation of AH outflow, and in the development of Rho kinase inhibitors as promising IOP- lowering agents for glaucoma treatment.

African Descent and Glaucoma Evaluation Study (ADAGES): Racial Differences in Optic Disc Hemorrhage and Beta-Zone Parapapillary Atrophy

PURPOSE

To investigate the differences in the frequency of optic disc hemorrhage (DH) and prevalence of beta-zone parapapillary atrophy (βPPA) between individuals of African descent (AD) and European descent (ED).

DESIGN

Prospective, multicenter, observational cohort.

PARTICIPANTS

A total of 1950 eyes of 1172 participants of the African Descent and Glaucoma Evaluation Study (ADAGES).

METHODS

Stereoscopic disc photographs of subjects with and without glaucomatous optic neuropathy (GON) followed during the first 13 years of the ADAGES underwent masked review searching for DH and βPPA. A total of 928 eyes (non-GON, 581; GON, 347) of 551 AD patients (non-GON, 334; GON, 217) and 1022 eyes (non-GON, 568; GON, 454) of 611 ED patients (non-GON, 334; GON, 277) were included. We compared the number of eyes with detected DH at any time during follow-up and eyes with βPPA between the AD and ED groups. The analyses were then adjusted for clinical parameters using multivariable logistic regression.

MAIN OUTCOME MEASURES

Differences in frequency of DH and prevalence of βPPA.

RESULTS

A total of 9395 stereoscopic disc photographs were reviewed. More ED eyes experience DH than AD eyes (49/1022 [4.8%] vs. 10/928 eyes [1.1%], respectively; P < 0.001), whereas βPPA had higher prevalence in AD eyes (675 eyes [72%] vs. 659 eyes [64%]; P < 0.001). In the final multivariable model, after controlling for confounders, AD eyes were less likely to have at least 1 detected DH than ED eyes (odds ratio [OR], 0.21; 95% CI, 0.10-0.45; P < 0.001) but were more likely to have βPPA than ED eyes (OR, 1.55; 95% CI, 1.12-2.14; P = 0.008).

CONCLUSIONS

Subjects of ED are at higher risk for developing DH compared with AD subjects, whereas AD subjects have greater prevalence of βPPA. These findings suggest that there are structural differences within the optic nerve complex between these groups. Further research is needed to determine whether racial differences in the frequency of DH and prevalence of βPPA affect the likelihood of glaucomatous progression.

Strategies to estimate the characteristics of 24-hour IOP curves of treated glaucoma patients during office hours

BACKGROUND

It is known that office-hour measurements might not adequately estimate IOP mean, peaks and fluctuations in healthy subjects. The purpose of the present study is to verify whether office-hour measurements in patients in different body positions can estimate the characteristics of 24-hour intraocular pressure (IOP) in treated POAG patients.

METHODS

The 24-hour IOP curves of 70 eyes of 70 caucasian patients with treated glaucoma were analyzed. Measurements were taken at 9 AM; 12, 3, 6, and 9 PM; and 12, 3, and 6 AM, both in the supine (TonoPen XL) and sitting (Goldmann tonometer) positions. The ability of five strategies to estimate IOP mean, peak and fluctuation was evaluated. Each method was analyzed both with regression of the estimate error on the real value and with "hit or miss" analysis.

RESULTS

The least biased estimate of the Peak IOP was obtained using measurements from both supine and sitting positions, also yielding the highest rate of correct predictions (which was significantly different from 3 of the remaining 4 strategies proposed, p < 0.05). Strategies obtained from the combination of supine, sitting and peak measurements resulted to be least biased for the Mean IOP and the IOP Fluctuation estimate, but all strategies were not found significantly different in terms of correct prediction rate (the only significant difference being between the two strategies based on sitting or supine measurements only, with the former being the one with the highest correct prediction rate).

CONCLUSIONS

The results of this study remark the concept that IOP is a dynamic parameter and that intensive measurement is helpful in determining its characteristics. All office-hour strategies showed a very poor performance of in correctly predicting the considered parameters within the thresholds used in this paper, all scoring a correct prediction rate below 52%.

Statistical analysis plan for the Laser-1st versus Drops-1st for Glaucoma and Ocular Hypertension Trial (LiGHT): a multi-centre randomised controlled trial

Background

The LiGHT trial (Laser-1st versus Drops-1st for Glaucoma and Ocular Hypertension Trial) is a multicentre randomised controlled trial of two treatment pathways for patients who are newly diagnosed with open-angle glaucoma (OAG) and ocular hypertension (OHT). The main hypothesis for the trial is that lowering intraocular pressure (IOP) with selective laser trabeculoplasty (SLT) as the primary treatment (‘Laser-1st’) leads to a better health-related quality of life than for those started on IOP-lowering drops as their primary treatment (‘Medicine-1st’) and that this is associated with reduced costs and improved tolerability of treatment. This paper describes the statistical analysis plan for the study.

Methods/Design

The LiGHT trial is an unmasked, multi-centre randomised controlled trial. A total of 718 patients (359 per arm) are being randomised to two groups: medicine-first or laser-first treatment. Outcomes are recorded at baseline and at 6-month intervals up to 36 months. The primary outcome measure is health-related quality of life (HRQL) at 36 months measured using the EQ-5D-5L. The main secondary outcome is the Glaucoma Utility Index. We plan to analyse the patient outcome data according to the group to which the patient was originally assigned. Methods of statistical analysis are described, including the handling of missing data, the covariates used in the adjusted analyses and the planned sensitivity analyses.

Trial registration

The trial was registered with the ISRCTN register on 23/07/2012, number ISRCTN32038223.

Diurnal versus office-hour intraocular pressure fluctuation in primary adult onset glaucoma

PURPOSE

To evaluates the role of measuring intraocular pressure (IOP) outside office-hour in primary adult onset glaucoma.

METHODS

This retrospective study included 100 cases of primary adult onset glaucoma. IOP readings obtained with Goldmann applanation tonometry between 7 am and 10 pm were compared to office-hour readings.

RESULTS

One hundred patients were enrolled (mean age: 58.64 ± 10.98 years) in the study. Overall, mean diurnal IOP was significantly higher than mean office IOP (p < 0.05). Two-thirds of the patients had peak IOP measurements outside office-hour. Mean diurnal IOP fluctuation (7.03 ± 2.69 mm Hg) was significantly higher than mean office IOP fluctuation (4.31 ± 2.6 mm Hg) (p < 0.003). There was a significant correlation between baseline IOP and fluctuation in IOP (r = 0.61, p<0.001).

CONCLUSION

The mean diurnal IOP and IOP fluctuations were higher than office-hour readings in patients with primary adult onset glaucoma. Diurnal monitoring may be particularly useful in patients with high baseline IOP.

The African Descent and Glaucoma Evaluation Study (ADAGES): predictors of visual field damage in glaucoma suspects

PURPOSE

To evaluate racial differences in the development of visual field (VF) damage in glaucoma suspects.

DESIGN

Prospective, observational cohort study.

METHODS

Six hundred thirty-six eyes from 357 glaucoma suspects with normal VF at baseline were included from the multicenter African Descent and Glaucoma Evaluation Study (ADAGES). Racial differences in the development of VF damage were examined using multivariable Cox proportional hazard models.

RESULTS

Thirty one of 122 African-descent participants (25.4%) and 47 of 235 European-descent participants (20.0%) developed VF damage (P = .078). In multivariable analysis, worse baseline VF mean deviation, higher mean arterial pressure during follow-up, and a race ∗ mean intraocular pressure (IOP) interaction term were significantly associated with the development of VF damage, suggesting that racial differences in the risk of VF damage varied by IOP. At higher mean IOP levels, race was predictive of the development of VF damage even after adjusting for potentially confounding factors. At mean IOPs during follow-up of 22, 24, and 26 mm Hg, multivariable hazard ratios (95% confidence intervals) for the development of VF damage in African-descent compared to European-descent subjects were 2.03 (1.15-3.57), 2.71 (1.39-5.29), and 3.61 (1.61-8.08), respectively. However, at lower mean IOP levels (below 22 mm Hg) during follow-up, African descent was not predictive of the development of VF damage.

CONCLUSION

In this cohort of glaucoma suspects with similar access to treatment, multivariate analysis revealed that at higher mean IOP during follow-up, individuals of African descent were more likely to develop VF damage than individuals of European descent.

A 1-year randomized study of the clinical and confocal effects of tafluprost and latanoprost in newly diagnosed glaucoma patients

Introduction

The aim of the present study was to compare the confocal and clinical features of newly diagnosed glaucoma patients receiving unpreserved prostaglandins (tafluprost) versus preserved prostaglandins (latanoprost).

Materials and Methods

40 patients were randomized to tafluprost 0.0015% (20 patients; 32 eyes) or latanoprost 0.005% + benzalkonium chloride 0.02% (20 patients; 35 eyes) once daily for 1 year. Inclusion criteria were new glaucoma diagnosis, and no ocular treatments for 6 months before the study. Patients were evaluated at baseline and every 3 months with a complete ophthalmologic evaluation, Schirmer’s test, break-up time test, confocal microscopy of the central cornea, and measurement of intraocular pressure (IOP). Investigators were masked to treatment. Both eyes were analyzed if they fulfilled inclusion criteria. Treatments and changes between follow-up and baseline were compared by analysis of variance (ANOVA), t test and Chi-square test.

Results

At baseline, the two groups had similar age, ocular surface and confocal findings; keratocyte activation was present in 40%, branching pattern in 85%, and beading in 75%, with no inter-group differences. At follow-up, no significant clinical changes were detected, apart from a drop of IOP by 3.6–4.2 mmHg in the two groups (p < 0.001, with no difference between treatments). Despite inter-treatment ANOVA for confocal microscopy being negative, subtle changes were present. During follow-up, all eyes without nerve branching pattern at baseline progressively developed it when treated with latanoprost, whereas no change occurred using tafluprost treatment (p = 0.05). None of the eyes without beading at baseline developed it at the end of the study in the tafluprost group, whereas beading did occur in 75% of patients treated with latanoprost (p = 0.05). Both treatments were associated with increased keratocyte activation at follow-up; the change from baseline was statistically significant after month 3 with latanoprost (p = 0.02) and after month 6 with tafluprost (p = 0.04).

Conclusions

The two study treatments had similar clinical effects, but tafluprost had a more favorable profile for some confocal parameters of the cornea.

Funding

Merck Sharp & Dohme International.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-015-0205-5) contains supplementary material, which is available to authorized users.

Differences in ocular blood flow in glaucoma between patients of African and European descent

PURPOSE

To investigate differences in ocular blood flow in individuals of African descent (AD) and European descent (ED) with open angle glaucoma (OAG).

PATIENTS AND METHODS

A retrospective data analysis was performed on OAG patients of AD and ED who were previously examined for ocular blood flow within the Department of Ophthalmology at Indiana University School of Medicine. Data analysis included blood pressure, heart rate, visual fields, intraocular pressure, ocular perfusion pressure, and color Doppler imaging of retrobulbar vessels. Color Doppler imaging measurements were performed on ophthalmic, central retinal, and nasal and temporal short posterior ciliary arteries, with peak systolic (PSV) and end diastolic velocities (EDV) as well as the Pourcelot vascular resistive index calculated for each vessel. Two-sample t tests of unequal variance were performed with P values <0.05 considered statistically significant.

RESULTS

OAG patients of AD had statistically significant lower retrobulbar blood flow values than patients of ED including lower ophthalmic artery PSV (P=0.0001), ophthalmic artery EDV (P=0.0008), central retinal artery PSV (P=0.01), temporal short posterior ciliary artery PSV (P=0.0037), and nasal short posterior ciliary artery PSV (P<0.0001). No significant differences were found in terms of intraocular pressure or visual field parameters.

CONCLUSIONS

Significantly lower blood flow values were identified in all retrobulbar blood vessels in AD compared with ED OAG patients. These findings suggest that the contribution of ocular blood flow to the disease process may be different in AD compared with ED OAG patients.

[Medicinal glaucoma therapy. What can we learn from large randomized clinical trials?]

The prospective multicenter randomized controlled clinical trials (RCTs) Ocular Hypertension Glaucoma Treatment Study (OHTS), Early Manifest Glaucoma Trial (EMGT), Advanced Glaucoma Intervention Study (AGIS), Collaborative Initial Glaucoma Treatment Study (CITGS) and Collaborative Normal Tension Glaucoma Study (CNGTS) are often named as landmarks for glaucoma management as the results of these studies provided the evidence for numerous therapeutic decisions in clinical practice. The studies confirmed the consensus that reduction of intraocular pressure reduces the risk of glaucoma progression covering the whole spectrum of glaucoma from ocular hypertension to advanced glaucoma. Furthermore, the identification of new risk factors allows a higher precision of assessment of the risk of progression. The RCTs achieved the main goal of high level of evidence, thus making progress in the understanding of glaucoma and its treatment and bridging consensus-based and evidence-based decisions. However, the implementation of the results into clinical practice needs adequate and accurate interpretation of the results.

Vascular considerations in glaucoma patients of African and European descent

Glaucoma is the leading cause of blindness in individuals of African descent (AD). While open-angle glaucoma (OAG) disproportionately affects individuals of AD compared with persons of European descent (ED), the physiological mechanisms behind this disparity are largely unknown. The more rapid progression and greater severity of the disease in persons of AD further raise the concern for identifying these underlying differences in disease pathophysiology between AD and ED glaucoma patients. Ocular structural differences between AD and ED patients, including larger optic disc area, cup:disc ratio and thinner corneas, have been found. AD individuals are also disproportionately affected by systemic vascular diseases, including hypertension, cardiovascular disease, stroke and diabetes mellitus. Abnormal ocular blood flow has been implicated as a risk factor for glaucoma, and pilot research is beginning to identify localized ocular vascular differences between AD and ED OAG patients. Given the known systemic vascular deficits and the relationship between glaucoma and ocular blood flow, exploring these concepts in terms of glaucoma risk factors may have a significant impact in elucidating the mechanisms behind the disease disparity in the AD population.

Optic nerve head morphology in glaucoma patients of African descent is strongly correlated to retinal blood flow

BACKGROUND/AIMS

To examine the relationship between change in optic nerve head (ONH) morphology and retinal blood flow in patients with open-angle glaucoma (OAG) of African (AD) and European descent (ED) over 3 years.

METHODS

112 patients with OAG (29 AD; 83 ED) underwent assessment of ONH morphology using Heidelberg retinal tomography (HRT-III), and retinal blood flow using confocal scanning laser Doppler. Repeated-measures analysis of covariance was used to compare baseline and 3-year measurements, and Pearson correlations were calculated to evaluate the relationships.

RESULTS

In OAG patients of AD, change in superior mean retinal blood flow was strongly, negatively correlated with change in cup/disc (C/D) area ratio (r=-0.78, p=0.020) and cup area (r=-0.75, p=0.0283) and strongly, positively correlated with change in rim area (r=0.74, p=0.0328) over 3 years. In OAG patients of AD, change in inferior mean retinal blood flow was strongly, negatively correlated with changes in C/D area ratio (r=-0.88, p=0.0156) and linear C/D ratio (r=-0.86, p=0.0265) over 3 years. In OAG patients of ED, these correlations were weak and did not reach statistical significance.

DISCUSSION

OAG patients of AD may have a stronger vascular component to their glaucoma pathophysiology than patients of ED.

Bioactive lysophospholipids: role in regulation of aqueous humor outflow and intraocular pressure in the context of pathobiology and therapy of glaucoma

Homeostasis of aqueous humor (AH) outflow and intraocular pressure (IOP) is essential for normal vision. Impaired AH outflow through the trabecular meshwork (TM) and a resultant elevation in IOP are common changes in primary open-angle glaucoma (POAG), which is the most prevalent form of glaucoma. Although elevated IOP has been recognized as a definitive risk factor for POAG and lowering elevated IOP remains a mainstay for glaucoma treatment, little is known about the molecular mechanisms, especially external cues and intracellular pathways, involved in the regulation of AH outflow in both normal and glaucomatous eyes. In addition, despite the recognition that increased resistance to AH outflow via the conventional pathway consisting of TM and Schlemm's canal is the main cause for elevated IOP, there are no clinically approved drugs that target the conventional pathway to lower IOP in glaucoma patients. The aim of this article is to briefly review published work on the importance of bioactive lysophospholipids (eg, lysophosphatidic acid and sphingosine-1-phosphate), their receptors, metabolism, signaling, and role in the regulation of AH outflow via the TM and IOP, and to discuss pharmacological targeting of key proteins in the lysophospholipid signaling pathways to lower IOP in glaucoma patients.

Twenty-four hour pattern of intraocular pressure and ocular perfusion pressure in night shift workers

PURPOSE

To investigate the intraocular pressure (IOP) and ocular perfusion pressure (OPP) in night shift workers.

METHODS

Seventy-one healthy individuals who work the night shift were evaluated. IOP and OPP were measured in the sitting position in each participant. Measurements were obtained at rest time (09:00, 12:00, 16:00) and night-shift time (20:00, 24:00, 04:00, 08:00).

RESULTS

The mean age of the 33 females and 38 males was 35.6 ± 7.5 years (range 20-53 years). Mean IOP values were different between the measurements at 9:00 and 12:00 (p = 0.00), at 9:00 and 16:00 (p = 0.00), at 12:00 and 16:00 (p = 0.00), at 16:00 and 24:00 (p = 0.02), at 24:00 and 04:00 (p = 0.02), and at 24:00 and 08:00 (p = 0.00). Mean OPP values were significantly different only between the measurements at 9:00 and 20:00 (p = 0.01).

CONCLUSION

This study revealed that IOP and OPP in night shift workers show 24-hour variations.

Short- and long-term phasing of intraocular pressure in stable and progressive glaucoma

AIMS

To evaluate short- (ST) and long-term (LT) intraocular pressure (IOP) in patients with stable (SG) and progressive glaucoma (PG).

MATERIALS AND METHODS

Fifty-two patients with treated glaucoma received a baseline 24-hour IOP curve and, every 6 months for 2 years, office-hour curve plus visual field test. Based on field changes, they were divided into 24 SG and 28 PG. ST and LT IOP mean, peak and fluctuation (standard deviation of measurements) were calculated. Parameters determining progression were evaluated by logistic regression.

RESULTS

At ST, SG and PG, respectively, had mean IOP of 16.8 ± 2.2 and 15.3 ± 1.8 mm Hg; peak of 19.7 ± 3.3, 17.4 ± 2.3 mm Hg; fluctuation of 2.3 ± 1.2, and 1.6 ± 0.6 mm Hg. LT parameters did not change in SG, whereas a significant increase of mean (+1.0 ± 1.5 mm Hg, p = 0.05), peak (2.0 ± 2.4 mm Hg, p = 0.0002), and fluctuation (0.5 ± 1.1 mm Hg, p = 0.008) occurred in PG. Mean, peak, and fluctuation were correlated, except mean and fluctuation in the long term. Association with progression was shown for change in mean IOP between ST and LT, and ST peak.

CONCLUSIONS

SG and PG may show different IOP parameters when intensively measured at baseline and follow-up. Mean IOP change between ST and LT periods and ST peak were the parameters associated with progression.

The rate of structural change: the confocal scanning laser ophthalmoscopy ancillary study to the ocular hypertension treatment study

PURPOSE

To compare rates of topographic change in ocular hypertensive eyes that develop primary open-angle glaucoma (POAG) compared to eyes that do not, and to identify factors that influence the rate of change.

DESIGN

Longitudinal, randomized clinical trial.

METHODS

Four hundred forty-one participants (832 eyes) in the Confocal Scanning Laser Ophthalmoscopy Ancillary Study to the Ocular Hypertension Treatment Study were included. POAG was defined as repeatable visual field, photography-based optic disc changes, or both. The rate of topographic change in the 52 participants (66 eyes) who developed POAG was compared with that of participants who did not develop POAG using multivariable mixed effects models.

RESULTS

In both univariate and multivariate analyses, the rate of rim area loss was significantly faster in eyes in which POAG developed than in eyes in which it did not (univariate mean, -0.0131 mm(2)/year and -0.0026 mm(2)/year, respectively). The significantly faster rate of rim area loss in black persons found in the univariate analysis did not remain significant when baseline disc area was included in the model. In multivariate analyses, the rate of rim area loss and other topographic parameters also was significantly faster in eyes with worse baseline visual field pattern standard deviation and higher intraocular pressure during follow-up. Moreover, a significant rate of rim area loss was detected in eyes in which POAG did not develop (P < .0001). The rate of rim area loss in eyes with an optic disc POAG endpoint was significantly faster than in those with a visual field POAG endpoint.

CONCLUSIONS

The rate of rim area loss is approximately 5 times faster in eyes in which POAG developed compared with eyes in which it did not. These results suggest that measuring the rate of structural change can provide important information for the clinical management of ocular hypertensive patients. Additional follow-up is needed to determine whether the statistically significant change in the eyes in which POAG did not develop represents normal aging or glaucomatous change not detected by conventional methods.

Visual field progression outcomes in glaucoma subtypes

PURPOSE

To determine whether glaucoma subtype is an independent risk factor for visual field (VF) progression.

METHODS

We reviewed the charts of glaucoma suspects and glaucoma patients seen in a referral practice between 1999 and 2009. Automated pointwise linear regression analysis determined the rates of VF change. A progression endpoint was determined when two or more adjacent test locations in the same hemifield showed a threshold sensitivity decline at a rate of ≥1.0 dB/year with p < 0.01.

RESULTS

We included 841 eyes (841 patients; mean age, 64.1 ± 12.6 years; mean number of VF tests, 10.8 ± 2.8; mean follow-up, 6.4 ± 1.7 years). The glaucomatous group consisted of angle-closure glaucoma (76 eyes), juvenile primary open-angle glaucoma (37 eyes), normal-tension glaucoma (81 eyes), pigmentary glaucoma (34 eyes), primary open-angle glaucoma (275 eyes) and exfoliative glaucoma (XFG, 84 eyes). Normal-tension glaucoma eyes were more likely to present with beta-zone parapapillary atrophy and disc haemorrhage (p < 0.01). Exfoliative glaucoma eyes had the fastest rates of global VF change (-0.65 dB/year), as well as the highest mean, fluctuation, and peak intraocular pressure during follow-up (16.5, 3.0 and 22.0 mmHg, respectively) and reached a progression endpoint more frequently (40%). After adjusting for all covariates, including the glaucoma phenotype, there was no difference among groups regarding global rates of VF change and the risk of reaching a progression endpoint.

CONCLUSIONS

Despite different clinical features, epidemiology and genetics, glaucoma phenotype is not an independent risk factor for VF progression. Rather, variations in well-known, reported risk factors remain important disease parameters that affect progression.

Determinants of medication adherence to topical glaucoma therapy

INTRODUCTION/PURPOSE

To determine the associations between medical, demographic, socioeconomic, and ocular factors and adherence to topical glaucoma ocular hypotensive therapy.

METHODS

One hundred sixteen patients with ocular hypertension or open-angle glaucoma from 2 tertiary glaucoma services participated in this prospective study. Adherence to ocular hypotensive therapy was measured using an electronic dose monitor (Travatan Dosing Aid, Alcon Laboratories Inc., Fort Worth, TX) and collected data at 3 months after enrollment. We used 3 different definitions of adherence: 1) Definition 1: the proportion of days taking the prescribed number of drops within 3 hours of the prescribed dosing time; 2) Definition 2: the proportion of days taking any drops within 3 hours of the prescribed dosing time; and 3) Definition 3: the proportion of days taking any drops within 6 hours of the prescribed dosing time. Univariate and multivariate models were used to determine the association between the 3 adherence definitions, medical, demographic, socioeconomic, and ocular factors at 3-month follow-up. The main outcome measures for this study were risk factors for poor objective medication adherence.

RESULTS

Adherence, using Definition 1, Definition 2, and Definition 3, was 64%, 75%, and 80%, respectively. Age, total number of other eye diseases, and race were significantly associated with full treatment adherence (Definition 1), with race alone significantly predicting 11% of full treatment adherence. For Definition 2, age, income, level of education, and total number of eye diseases were significantly associated with partial adherence (3 h), again race alone significantly predicted 15% of partial adherence (any drops within 3 h). For Definition 3, race, income, level of education, and total number of other eye diseases significantly predicted partial adherence (any drops within 6 h), both race and income predicted 19% of partial treatment adherence. Significant differences for adherence rates between patients of European descent and those of African descent were found for all 3 definitions with those who were less adherent more likely to be of African descent.

CONCLUSIONS

Electronic dose monitors provide important information regarding adherence to topical ocular hypotensive medications in glaucoma patients. Electronic dose monitors show low adherence in a significant number of participants. Future studies are needed to determine the reasons for these differences in health behaviors related to glaucoma treatment, which should guide treatment of poor adherence with glaucoma therapy.

Reliability of RTVue, Visante, and slit-lamp adapted ultrasonic pachymetry for central corneal thickness measurement

PURPOSE

To evaluate reliability of Fourier-domain optical coherence tomography (OCT) (RTVue), time-domain OCT (Visante), and slit-lamp adapted ultrasonic pachymetry (SL-US) in the measurement of central corneal thickness (CCT).

MATERIALS AND METHODS

Thirty healthy volunteers visited our clinic 3 times and fifty eyes were measured by one physician. RTVue and Visante were randomly performed, and then SL-US, in which the ultrasound probe was inserted into the Goldmann tonometry mount, was done. During the second visit, each measurement was repeated 3 times. Measurements on the second visit were averaged, and agreement among the instruments was investigated with Bland-Altman plots.

RESULTS

RTVue showed smaller repeatability coefficient than Visante and SL-US (4.7, 8.3, and 7.7 μm, respectively). Intersession reproducibility of RTVue and Visante was worse than their repeatability. CCT of RTVue was estimated to be maximally different by 11.8 μm from CCT of Visante and 8.8 μm from CCT of SL-US. The repeatability coefficient of SL-US was 7.7 μm and its reproducibility was similar to the repeatability.

CONCLUSION

CCT measured by RTVue showed good reliability and generally agreed with Visante and SL-US. SL-US was as reliable as triple touching conventional US even with a single touch on the cornea.