Management of the glaucoma patient progressing at low normal intraocular pressure

Promising therapeutic targets for neuroprotection in retinal disease

PURPOSE OF REVIEW

Neurodegeneration is a common endpoint of various blinding retinal diseases. Yet, despite exciting advances in disease treatment, there continues to exist a critical need for the development of neuroprotective strategies to prevent retinal cell death. Here, we summarize the recent advances in neuroprotective strategies.

RECENT FINDINGS

From laboratory deciphering of the mechanisms involved in disease, many novel neuroprotective strategies have emerged and are currently under investigation for the treatment of various retinal and ocular diseases such as inherited retinal degeneration, retinal detachment, diabetic retinopathy, age-related macular degeneration, macular telangiectasia type 2, and glaucoma. These strategies include gene therapies, Fas inhibition, and targeting inflammatory, metabolic and reduction-oxidation abnormalities. Interestingly, investigation of several treatments across different diseases suggests shared neuroprotection mechanisms that can be targeted regardless of the particular disease.

SUMMARY

Retinal neuroprotection can improve treatment of different retinal diseases. Fortunately, the current landscape, with a plethora of novel neuroprotective therapies, portends a better future for patients.

Association between 91 circulating inflammatory proteins and the risk of glaucoma: A Mendelian randomization study

Glaucoma is a leading cause of irreversible blindness worldwide, with its pathogenesis incompletely understood. Inflammation, as an important aspect of glaucoma, has attracted increasing attention. In this study, we performed a Mendelian randomization (MR) analysis to investigate the association between 91 circulating inflammatory proteins and glaucoma. First, a bidirectional MR was employed to screen for inflammatory proteins that potentially influence glaucoma risk, with the findings further confirmed by a replication sample MR. Then, a mediation analysis was employed to assess the mediating effects of glaucoma endophenotypes on glaucoma. Finally, we performed a subgroup MR to investigate the association between circulating proteins and glaucoma subtypes, including primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). The bidirectional MR suggested 7 out of the 91 proteins were possibly related with glaucoma risk, with T-cell surface glycoprotein CD5 (CD5) (odds ratio (OR) = 0.87; 95% confidence interval (CI): 0.81-0.94; P = 2.46 × 10-4) passing false discovery rate correction. This result was verified by the replication sample MR. The mediation analysis revealed that intraocular pressure (IOP) (β=-0.05; 95% CI: -0.02--0.09; P = 1.56 × 10-3) was a mediator of CD5's protective effect on glaucoma. The subgroup MR indicated that CD5 conferred a protective causal effect specifically on POAG, not PACG. Moreover, IOP served as a mediator in the association between CD5 and POAG, explaining a proportion of 38.29% of CD5's protective effect against POAG. Our findings suggest a negative causal association between circulating CD5 and POAG risk, which is partially mediated by IOP. This indicates that targeted CD5 therapy may be beneficial to POAG eyes.

The endocannabinoid system and ophthalmic pathologies: a review of molecular mechanisms and its implications for clinical practice

Within the last decade the role of the endocannabinoid system (ECS) has been a significant part of ophthalmic research, including both ocular physiology and the development of eye pathologies. It is known that this widespread cell-signaling system is involved in retinal neurobiological processes, including visual signal processing, as well as neurotransmission. Furthermore, various research indicated the involvement of ECS in the molecular basis of various pathologies, mostly glaucoma, diabetic retinopathy, and age-related macular degeneration (AMD). Therefore, the researchers believe that this biological system, its receptors, pathways, and ligands might be considered as an auxiliary compound to reduce the number of patients suffering from ophthalmic diseases. Despite presented in the literature effects of the endocannabinoid system in the eye, none of the current ECS reviews presented a comprehensive description of the endocannabinoid system, its compounds, and, subsequently ophthalmic disorders. Thus, the aim of this review was to summarize all the major data, including the most up-to-date research, concerning a correlation between the endocannabinoid system and the major ophthalmic pathologies.

Application of Quality by Design in the Development of Hydrogen Sulfide Donor Loaded Polymeric Microparticles

Hydrogen sulfide (H2S) is a multifaceted gasotransmitter molecule which has potential applications in many pathological conditions including in lowering intraocular pressure and providing retinal neuroprotection. However, its unique physicochemical properties pose several challenges for developing its efficient and safe delivery method system. This study aims to overcome challenges related to H2S toxicity, gaseous nature, and narrow therapeutic concentrations range by developing polymeric microparticles to sustain the release of H2S for an extended period. Various formulation parameters and their interactions are quantitatively identified using Quality-by-Design (QbD) approach to optimize the microparticle-based H2S donor (HSD) delivery system. Microparticles were prepared using a solvent-evaporation coacervation process by using polycaprolactone (PCL), soy lecithin, dichloromethane, Na2S.9H2O, and silicone oil as polymer, surfactant, solvent, HSD, and dispersion medium, respectively. The microparticles were characterized for size, size distribution, entrapment efficiency, and H2S release profile. A Main Effects Screening (MES) and a Response Surface Design (RSD) model-based Box-Behnken Design (BBD) was developed to establish the relationship between critical process parameters (CPPs) and critical quality attributes (CQAs) qualitatively and quantitatively. The MES model identified polymer to drug ratio and dispersion medium quantity as significant CPPs among others, while the RSD model established their quantitative relationship. Finally, the target product performance was validated by comparing predicted and experimental outcomes. The QbD approach helped in achieving overall desired microparticle characteristics with fewer trials and provided a mathematical relationship between the CPPs and the CQAs useful for further manipulation and optimization of release profile up to at least 30 days.

Long-Term Surgical Outcomes of Glaucoma Drainage Implants in Eyes with Preoperative Intraocular Pressure Less than 19 mmHg

Background

This retrospective review reports on patients who underwent glaucoma drainage implant (GDI) surgery and had baseline intraocular pressure (IOP) of ≤18 mmHg with at least one year of follow-up.

Methods

Clinical data of 67 eyes of 67 patients were collected from patients' charts, and the outcomes of GDI were evaluated until 7 years. GDI failure was defined as IOP reduction of less than 20% from the baseline at two consecutive visits three months after surgery, decline to no light perception, or if additional glaucoma surgery was performed.

Results

The average age was 65.9 ± 13.2 years. Most cases were male (52.2%), White (53.7%), and had primary open-angle glaucoma (62.7%). Forty-four eyes had prior glaucoma surgery (68.6%) and 46 (68.6%) had severe glaucoma. Though postoperative (postop) IOP changes were insignificant, the average postop number of medications dropped from 2.4 ± 1.4 to 1.9 ± 1.2 medications two years after surgery (p = 0.0451). Postop complications (23.9%) included GDI exposure (7.5%), inflammation (4.5%), shallow anterior chamber (4.5%), and strabismus (1.5%). Hypotony was observed in 4 eyes (5.9%), none of which developed hypotony maculopathy. The cumulative one-year failure rate was 56.7%, most of which were due to failure to lower IOP.

Conclusion

In patients with baseline IOP ≤18 mmHg who had GDI surgery, though the change in IOP was not statistically significant, the number of medications dropped and visual field progression slowed in a subset of patients with adequate perimetric data. Due to a relatively high rate of complications and limited effectiveness in lowering IOP, GDI should be cautiously used in these eyes.

Early diagnostics and interventional glaucoma

The glaucoma treatment paradigm is starting to change from a more reactive approach that relies on topical medications to a more proactive approach that leverages procedural interventions. This evolution toward interventional glaucoma has been enabled by a growing array of lower-risk minimally invasive procedures such as laser trabeculoplasty, minimally invasive glaucoma surgery, and procedural pharmaceuticals. A common feature of these glaucoma interventions-as with all glaucoma interventions-is the need for early, prompt, and accurate diagnosis. The present review summarizes new and upcoming developments in glaucoma diagnostics. These include technologies and techniques for home-based intraocular pressure measurement, novel visual field platforms, photography- and optical coherence tomography-based visualization, and artificial intelligence applications. They also include emerging technologies such as mitochondrial flavoprotein fluorescence imaging, detection of apoptosing retinal cells, collector channel visualization, and genetic testing. These diagnostic modalities have the potential to circumvent the limitations of traditional diagnostic methods. By increasing the frequency and feasibility of obtaining valuable glaucoma data with more rapid detection of disease and progression, these diagnostics may enable an interventional approach to glaucoma treatment for the betterment of patient care.

Therapeutic Potential of Cannabinoids in Glaucoma

Glaucoma is a leading cause of irreversible blindness worldwide. To date, intraocular pressure (IOP) is the only modifiable risk factor in glaucoma treatment, but even in treated patients, the disease can progress. Cannabinoids, which have been known to lower IOP since the 1970s, have been shown to have beneficial effects in glaucoma patients beyond their IOP-lowering properties. In addition to the classical cannabinoid receptors CB1 and CB2, knowledge of non-classical cannabinoid receptors and the endocannabinoid system has increased in recent years. In particular, the CB2 receptor has been shown to mediate anti-inflammatory, anti-apoptotic, and neuroprotective properties, which may represent a promising therapeutic target for neuroprotection in glaucoma patients. Due to their vasodilatory effects, cannabinoids improve blood flow to the optic nerve head, which may suggest a vasoprotective potential and counteract the altered blood flow observed in glaucoma patients. The aim of this review was to assess the available evidence on the effects and therapeutic potential of cannabinoids in glaucoma patients. The pharmacological mechanisms underlying the effects of cannabinoids on IOP, neuroprotection, and ocular hemodynamics have been discussed.

Surgical Results of Trabeculectomy among Groups Stratified by Prostaglandin-Associated Periorbitopathy Severity

PURPOSE

To report the role of prostaglandin-associated periorbitopathy (PAP) severity in the surgical effectiveness of trabeculectomy (LEC).

DESIGN

Retrospective observational case series.

PARTICIPANTS

A total of 139 consecutive eyes of 139 Japanese subjects (74 men, 65 women; mean age ± standard deviation, 65.7 ± 10.6 years) who underwent LEC were included. All had primary open-angle glaucoma (POAG), no history of conjunctival incisional surgery, completed all postoperative visits for 12 months, and information on the PAP severity using the Shimane University PAP Grading System (SU-PAP).

METHODS

Data were collected from a medical chart review at 2 hospitals.

MAIN OUTCOME MEASURES

Comparison of surgical success rates among groups stratified by SU-PAP grades 0 to 3 by survival curve analysis using the definitions of failure based on surgical intervention other than laser suture lysis (LSL), intraocular pressure (IOP) reduction below 20%, postoperative IOP exceeding 15 mmHg (definition A) or 12 mmHg (definition B), and a postoperative IOP below 6 mmHg.

RESULTS

Twelve months postoperatively, the success rates of grades 0, 1, 2, and 3 were 86%, 68%, 40%, and 0%, respectively, for definition A (P < 0.0001, log-rank test) and 86%, 61%, 36%, and 0%, respectively, for definition B (P < 0.0001). Interventions other than LSL (P < 0.0001, Cochran-Armitage trend test), IOP reduction less than 20% (P = 0.010), and IOP exceeding 15 mmHg (P = 0.016) or 12 mmHg (P < 0.0001) were associated with surgical failure; IOP under 6 mmHg was not (P = 0.31). The proportional hazard model for definition A showed that compared with grade 0, grade 2 (risk ratio [RR], 5.82, P = 0.0043) and grade 3 (RR, 12.2, P = 0.0003) were associated with surgical failure. For definition B, grade 1 (RR, 3.53, P = 0.040), grade 2 (RR, 6.65, P = 0.0021), and grade 3 (RR, 12.0, P = 0.0003) were associated with surgical failure. Differences in age, gender, preoperative IOP and medications, refractive error, and simultaneous cataract surgery were not associated with surgical failure in both models.

CONCLUSIONS

The preoperative presence of severe PAP worsens the 1-year success rate of LEC in patients with POAG. To retain the surgical effectiveness, treating physicians should prevent patients from progressing to severe PAP, an avoidable side effect, by switching or stopping the causative medications.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

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.

Unmet needs in glaucoma therapy: The potential role of hydrogen sulfide and its delivery strategies

Glaucoma is an optic neuropathy disorder marked by progressive degeneration of the retinal ganglion cells (RGC). It is a leading cause of blindness worldwide, prevailing in around 2.2% of the global population. The hallmark of glaucoma, intraocular pressure (IOP), is governed by the aqueous humor dynamics which plays a crucial role in the pathophysiology of the diesease. Glaucomatous eye has an IOP of more than 22 mmHg as compared to normotensive pressure of 10-21 mmHg. Currently used treatments focus on reducing the elevated IOP through use of classes of drugs that either increase aqueous humor outflow and/or decrease its production. However, effective treatments should not only reduce IOP, but also offer neuroprotection and regeneration of RGCs. Hydrogen Sulfide (H₂S), a gasotransmitter with several endogenous functions in mammalian tissues, is being investigated for its potential application in glaucoma. In addition to decreasing IOP by increasing aqueous humor outflow, it scavenges reactive oxygen species, upregulates the cellular antioxidant glutathione and protects RGCs from excitotoxicity. Despite the potential of H₂S in glaucoma, its delivery to anterior and posterior regions of the eye is a challenge due to its unique physicochemical properties. Firstly, development of any delivery system should not require an aqueous environment since many H₂S donors are susceptible to burst release of the gas in contact with water, causing potential toxicity and adverse effects owing to its inherent toxicity at higher concentrations. Secondly, the release of the gas from the donor needs to be sustained for a prolonged period of time to reduce dosing frequency as per the requirements of regulatory bodies. Lastly, the delivery system should provide adequate bioavailability throughout its period of application. Hence, an ideal delivery system should aim to tackle all the above challenges related to barriers of ocular delivery and physicochemical properties of H₂S itself. This review discusses the therapeutic potential of H₂S, its delivery challenges and strategies to overcome the associated chalenges.

Home Self-tonometry Trials Compared with Clinic Tonometry in Patients with Glaucoma

PURPOSE

This study examined characteristics of intraocular pressure (IOP) as measured during home tonometry in comparison with in-clinic tonometry in patients with glaucoma.

DESIGN

Retrospective cross-sectional study of glaucoma patients who completed 1 week of self-tonometry at a single academic center.

PARTICIPANTS

Patients with glaucoma who completed home tonometry trials with the iCare HOME tonometer (iCare USA) for any reason.

METHODS

Home IOP measurements were compared with in-clinic tonometry performed during the 5 visits preceding home tonometry. Maximum daily IOP was correlated to time of day. Generalized estimating equations were used to evaluate patient characteristics and clinic-derived variables that predicted differences between home and clinic IOP.

MAIN OUTCOME MEASURES

IOP mean, maximum, minimum, range, standard deviation and coefficient of variation were compared between clinic and home tonometry. IOP mean daily maximum (MDM) and mean daily range were calculated to describe recurrent IOP spiking.

RESULTS

A total of 107 eyes from 61 patients were analyzed. Mean age was 63.2 years (standard deviation [SD], 14.0 years) and 59.0% were women. Mean clinic and home IOPs were 14.5 mmHg (SD, 4.7 mmHg) and 13.6 mmHg (SD, 5.1 mmHg). Home tonometry identified significantly higher maximum IOP, lower minimum IOP, and greater IOP range than clinic tonometry (P < 0.001). Maximum daily IOP occurred outside of clinic hours (8 am-5 pm) on 50% of days assessed and occurred between 4:30 am and 8 am on 24% of days. Mean daily maximum IOP exceeded maximum clinic IOP in 44% of patients and exceeded target IOP by 3 mmHg, 5 mmHg, or 10 mmHg in 31%, 15%, and 6% of patients, respectively. Patient characteristics that predicted significant deviations between MDM and mean clinic IOP or target IOP in multivariate models included younger age, male gender, and absence of prior filtering surgery.

CONCLUSIONS

Self-tonometry provides IOP data that supplements in-clinic tonometry and would not be detectable over daytime in-clinic diurnal curves. A subset of patients in whom home tonometry was ordered by their glaucoma clinician because of suspicion of occult IOP elevation demonstrated reproducible IOP elevation outside of the clinic setting. Such patients tended to be younger and male and not to have undergone previous filtering surgery.

Long-Term Effectiveness and Safety of Tafluprost, Travoprost, and Latanoprost in Korean Patients with Primary Open-Angle Glaucoma or Normal-Tension Glaucoma: A Multicenter Retrospective Cohort Study (LOTUS Study)

This multicenter retrospective cohort study compared the effectiveness and safety of long-term tafluprost, travoprost, or latanoprost in patients with primary open-angle glaucoma (POAG) or normal-tension glaucoma (NTG). Data were extracted from electronic medical records of 300 patients treated with tafluprost, travoprost, or latanoprost for >6 months. Propensity matching for age and sex was used for effectiveness and safety comparisons. The primary endpoint was visual field (VF) progression via mean deviation (MD) slope. Secondary endpoints were change of MD, intraocular pressure, pattern standard deviation, VF index, and advanced glaucoma intervention study score. Treatment-related adverse events (AEs) were also compared between groups. Overall, 216 POAG or NTG patients were matched into Match Set 1 (72 patients/group), and 177 NTG-only patients in Match Set 2 (59 patients/group) according to: age (mean: 61, 62 years) and sex (male: 53, 56%). There were no statistically significant between-group differences regarding MD slope (p = 0.413, p = 0.374 in Match Sets 1 and 2, respectively). There were no significant between-group differences/tendencies regarding secondary endpoints. No AEs were serious, and there were no significant between-group differences regarding reported AEs. In patients with POAG or NTG, long-term tafluprost, travoprost, or latanoprost showed similar effects. All three prostaglandin analogs had good long-term safety profiles.

Evaluation of Primary Angle-Closure Glaucoma Susceptibility Loci for Estimating Angle Closure Disease Severity

PURPOSE

To investigate whether recently identified genetic loci for primary angle-closure glaucoma (PACG) are associated with disease severity.

DESIGN

Case-control study.

PARTICIPANTS

Eight hundred four PACG patients and 943 control participants of Chinese ethnicity from Singapore.

METHODS

The 8 PACG-associated single nucleotide polymorphisms (SNPs; rs11024102 at PLEKHA7, rs3753841 at COL11A1, rs1015213 located between PCMTD1 and ST18 on chromosome 8q, rs3816415 at EPDR1, rs1258267 at CHAT, rs736893 at GLIS3, rs7494379 at FERMT2, and rs3739821 mapping in between DPM2 and FAM102A) identified from genome-wide association studies were tested for association with disease severity using logistic regression adjusted for age and gender. A P value of 0.006 was set as significant after Bonferroni correction for testing of 8 loci. We also calculated the weighted genetic risk score (GRS) weighted by the estimated individual SNP effect size on PACG calculated as logarithm of the odds ratio (OR). Disease severity was based on the visual field mean deviation (MD) and classified as early to moderate (MD, >-12 dB) and severe (MD, <-20 dB).

MAIN OUTCOME MEASURES

Association of PACG loci with severe disease.

RESULTS

Of the 804 PACG patients, genotyping data were available for 768 individuals and included 436 with mild-to-moderate PACG and 206 with severe PACG. The PACG patients were significantly older (mean age, 64.3 ± 9.1 years vs. 56.4 ± 8.9 years; P < 0.001) and there were proportionately more women compared with control participants (58.4% vs. 49.0%; P < 0.001). Of the 8 loci investigated, we observed significant evidence of association with severe PACG at 1 SNP, namely rs3816415 in EPDR1 (OR, 2.03; 95% confidence interval [CI], 1.49-2.78; P = 1 × 10^-5). A higher-weighted GRS was associated significantly with severe PACG, with an OR of 3.11 (95% CI, 1.95-4.96) comparing the lowest quartile with the highest quartile.

CONCLUSIONS

Our results show that EPDR1 is associated significantly with severe PACG, suggesting that it may predispose patients to more aggressive disease development. Individuals with PACG with a higher GRS were associated with a higher risk of severe PACG.