The effects of topical antiglaucoma drugs as monotherapy on the ocular surface: a prospective study

Preservatives and ocular surface disease: A review

Ocular surface disease (OSD) is a complex condition that can cause a range of symptoms (e.g, dryness, irritation, and pain) and can significantly impact the quality of life of affected individuals. Iatrogenic OSD, a common finding in patients with glaucoma who receive chronic therapy with topical ocular antihypertensive drugs containing preservatives such as benzalkonium chloride (BAK), has been linked to damage to the ocular surface barrier, corneal epithelial cells, nerves, conjunctival goblet cells, and trabecular meshwork. Chronic BAK exposure activates inflammatory pathways and worsens symptoms, compromising the success of subsequent filtration surgery in an exposure-dependent manner. In eyes being treated for glaucoma, symptomatic treatment of OSD may provide some relief, but addressing the root cause of the OSD often necessitates reducing or, ideally, eliminating BAK toxicity. Strategies to decrease BAK exposure in patients with glaucoma encompass the use of preservative-free formulations or drugs with alternative and less toxic preservatives such as SofZia®, Polyquad, potassium sorbate, or Purite®. Though the benefits of these alternative preservatives are largely unproven, they might be considered when financial constraints prevent the use of preservative-free versions. For patients receiving multiple topical preserved drugs, the best practice is to switch to nonpreserved equivalents wherever feasible, regardless of OSD severity. Furthermore, nonpharmacological approaches, including laser or incisional procedures, should be considered. This review explores the effects of BAK on the ocular surface and reviews strategies for minimizing or eliminating BAK exposure in patients with glaucoma in order to significantly improve their quality of life and prevent complications associated with chronic exposure to BAK.

The use of benzalkonium chloride in topical glaucoma treatment: An investigation of the efficacy and safety of benzalkonium chloride-preserved intraocular pressure-lowering eye drops and their effect on conjunctival goblet cells

ENGLISH SUMMARY

Glaucoma is a leading cause of the global prevalence of irreversible blindness. The pathogenesis of glaucoma is not entirely known, but the major risk factors include advancing age, genetic predisposition, and increased intraocular pressure (IOP). The only evidence-based treatment is a lowering of IOP through the use of eye drops, laser procedures, or surgical interventions. Although laser treatment is gaining recognition as a first-choice treatment option, the most common approach for managing glaucoma is IOP-lowering eye drops. A major challenge in the treatment is the occurrence of adverse events and poor adherence. In this context, the ocular surface is an area of great concern, as most glaucoma patients have dry eye disease (DED), which is largely caused by eye drops. Preservation with benzalkonium chloride (BAK) is a controversial topic due to its potential role as a significant cause of DED. A systematic review and meta-analyses investigate potential differences in efficacy and safety between BAK-preserved and BAK-free anti-glaucomatous eye drops (I). Many of the included studies report on ocular surface damage caused by the application of BAK-preserved eye drops. However, the meta-analyses addressing hyperemia, number of ocular adverse events, and tear break-up time did not identify any significant differences. The latter is likely due to varying measurement methods, different endpoints, and study durations. It is, therefore, possible that the large variations between the studies conceal differences in the safety profiles. The efficacy meta-analysis finds that there are no differences in the IOP-lowering effect between BAK-preserved and BAK-free eye drops, indicating that BAK is not necessary for the effectiveness of eye drops. To promote more homogeneous choices of endpoints and methods when evaluating BAK-preserved and BAK-free glaucoma treatments, a Delphi consensus statement was performed. In this study, glaucoma experts and ocular surface disease experts reached consensus on the key factors to consider when designing such studies (II). The hope is to have more studies with comparable endpoints that can systematically show the potentially adverse effects of BAK. The preclinical studies in the current Ph.D. research focus on conjunctival goblet cells (GCs). GCs are important for the ocular surface because they release the mucin MUC5AC, which is an essential component of the inner layer of the tear film. BAK preservation may damage the GCs and result in a low GC density, leading to an unstable tear film and DED. The most commonly used IOP-lowering drugs are prostaglandin analogs (PGAs). Thus, the conducted studies investigate the effect of PGAs preserved in different ways on GCs. BAK-preserved latanoprost is cytotoxic to primary cultured human conjunctival GCs and results in a scattered expression of MUC5AC, in contrast to negative controls, where MUC5AC is localized around the cell nucleus (III). Preservative-free (PF) latanoprost is not cytotoxic and does not affect the MUC5AC expression pattern. Furthermore, BAK-preserved travoprost is found to be cytotoxic in a time-dependent manner, while Polyquad®-preserved travoprost does not affect GC survival at any measured time point (IV). Both Polyquad and BAK induce scattered expression of MUC5AC. The cytotoxicity of BAK-preserved PGA eye drops is higher compared to the safer profile of PF and Polyquad-preserved PGA eye drops (V). Additionally, PF latanoprost does not increase the release of the inflammatory markers interleukin (IL)-6 and IL-8, unlike BAK-preserved latanoprost. A review highlights the active and inactive components of IOP-lowering eye drops (VI). Several preclinical and clinical studies have identified adverse effects of BAK. Although other components, such as the active drug and phosphates, can also cause adverse events, the review clearly states that BAK alone is a major source of decreased tolerability. The conclusion of this thesis is that BAK preservation is unnecessary and harmful to the ocular surface. The preclinical studies demonstrate that GCs die when exposed to BAK. Furthermore, they find that BAK induces a pro-inflammatory response. The review included in the thesis concludes that BAK should be phased out of eye drops for chronic use. Overall, the inclusion of BAK poses a risk of developing DED and poor adherence, which can ultimately lead to disease progression and blindness.

Ocular surface disease: a known yet overlooked side effect of topical glaucoma therapy

Ocular surface disease (OSD), a disorder affecting the lacrimal and meibomian glands and the corneal and conjunctival epithelium, is a well-known complication of topical glaucoma therapy. OSD can present as a new or pre-existing condition that virtually any anti-glaucoma formulation can exacerbate. As such, both glaucoma and OSD frequently coexist. Typical OSD symptoms include ocular discomfort, redness, burning, and dryness, whereas signs include periorbital and eyelid skin pigmentation, conjunctival scarring, and superficial punctate keratitis. Pressure-lowering eyedrops can cause toxic, allergic, and inflammatory reactions on the ocular surface. The latter can result from either preservatives or direct toxicity from the active molecule. Although usually mild, OSD can cause significant symptoms that lead to poor quality of life, decreased compliance to therapy, glaucoma progression, and worse visual outcomes. Given the chronic nature of glaucoma, lack of curative therapy, and subsequent lifelong treatment, addressing OSD is necessary. This manuscript aims to provide an up-to-date overview of OSD's signs, symptoms, and pathogenic mechanisms from glaucoma therapy toxicity.

Glaucoma and Ocular Surface Disease: More than Meets the Eye

Understanding the association between ocular surface disease and glaucoma is important for improving adherence to treatment and introducing practical solutions. While topical antihypertensive medications for glaucoma are well tolerated according to short-term studies, there is little evidence on their long-term effects. Since they are often required for many years, the effects of these drops on the ocular surface become important in regard to quality of life and adherence. In this nonsystematic review performed in April 2022, we summarize what is known about the relationship between glaucoma and ocular surface disease. Specifically, we examine how each class of topical glaucoma drops affects the ocular surface. We then review the treatment of ocular surface disease for patients on topical glaucoma therapy. Finally, we discuss treatments that may reduce or eliminate the burden of topical medications.

A Narrative Review of Ocular Surface Disease Related to Anti-Glaucomatous Medications

Topical anti-glaucomatous medications are still the most important measure to lower intraocular pressure. Large number of studies have confirmed that long-term use of anti-glaucomatous eye drops, especially containing benzalkonium chloride, a preservative, can cause or aggravate ocular surface injury. Ocular surface diseases damage the ocular microenvironmental health status, reduce the patients’ compliance with the treatment, and finally affect the treatment result. Therefore, the ocular surface management of patients with glaucoma is very important. This includes the selection of drugs that are better tolerated according to individual conditions, preservative-free formulations, drugs that protect against ocular surface disease, or selecting surgery and laser treatment, to prevent the damage to the ocular surface by topical anti-glaucomatous drugs.

Inter-Eye Comparison of the Ocular Surface of Glaucoma Patients Receiving Surgical and Medical Treatments

Background: Ocular surface frequently affects glaucoma patients. In this paper we aimed at evaluating the impact of glaucoma surgery on the ocular surface of patients who received unilateral trabeculectomy. Methods: 26 consecutive patients successfully treated with trabeculectomy on one eye (Trab Eye) and under control with topical treatments on the fellow eye (Med Eye) were included in this observational study. They received IDEEL and OSDI questionnaires, Tear Film Osmolarity (TFO), grading of conjunctival hyperemia, fluorescein tear break-up time (tBUT), grading of corneal staining and Schirmer test. Results: IDEEL and OSDI scores were 48 ± 38 and 11 ± 12, respectively, with moderate correlation (r = 0.50, p = 0.03). Compared with Med eyes, Trab Eyes had higher tBUT (6.5 ± 3.5 vs. 5.1 ± 2.7 s, p = 0.004), lower conjunctival hyperemia (0.8 ± 0.9 and 1.7 ± 1.1 respectively, p < 0.001) and lower corneal staining (0.3 ± 0.5 and 0.6 ± 0.5, respectively, p = 0.03). Correlation between corneal staining and conjunctival hyperemia was 0.55 in Trab Eyes (p = 0.01) and 0.44 in Med Eyes (p > 0.05). Patients with bilateral corneal staining had had threefold worse questionnaire scores (p < 0.05). The duration of treatment and the daily exposure to preservatives did not directly affect OS parameters in this cohort of patients. Conclusions: Patients receiving successful trabeculectomy showed better OS homeostasis (higher TBUT, lower grading of conjunctival hyperemia and corneal staining) than fellow medically treated eyes. Presence of corneal epithelial damage in both eyes is the factor more consistently affecting questionnaire scores.

Confocal Microscopy and Anterior Segment Optical Coherence Tomography Imaging of the Ocular Surface and Bleb Morphology in Medically and Surgically Treated Glaucoma Patients: A Review

Glaucoma patients often suffer from ocular surface disease (OSD) caused by the chronic administration of topical anti-glaucoma medications, especially in cases of long-term therapy with preserved or multiple drugs. Additionally, glaucoma surgery may determine ocular surface changes related to the formation and location of the filtering bleb, the application of anti-mitotic agents, and the post-operative wound-healing processes within the conjunctiva. Recently, several studies have evaluated the role of advanced diagnostic imaging technologies such as in vivo confocal microscopy (IVCM) and anterior segment-optical coherence tomography (AS-OCT) in detecting microscopic and macroscopic features of glaucoma therapy-related OSD. Their clinical applications are still being explored, with recent particular attention paid to analyzing the effects of new drug formulations and of minimally invasive surgical procedures on the ocular surface status. In this review, we summarize the current knowledge about the main changes of the ocular surface identified at IVCM and AS-OCT in glaucoma patients under medical therapy, or after surgical treatment.

Pharmacological Profile and Ocular Hypotensive Effects of Cromakalim Prodrug 1, a Novel ATP-Sensitive Potassium Channel Opener, in Normotensive Dogs and Nonhuman Primates

Purpose: To evaluate pharmacokinetic parameters and ocular hypotensive effects of cromakalim prodrug 1 (CKLP1) in normotensive large animal models. Methods: Optimal CKLP1 concentration was determined by dose response and utilized in short- (5-8 days) and long-term (60 days) evaluation in hound dogs (n = 5) and African Green Monkeys (n = 5). Blood pressure was recorded 3-5 times per week with a tail cuff. Concentrations of CKLP1 and the parent compound levcromakalim were assessed in hound dog plasma and select tissues by LC-MS/MS after bilateral ocular treatment with CKLP1 for 8 days. Pharmacokinetic parameters were calculated from days 1, 4, and 8 data. After necropsy, histology was assessed in 43 tissue samples from each animal. Results: In hound dogs and African Green monkeys, 10 mM CKLP1 (optimal concentration) significantly lowered intraocular pressure (IOP) by 18.9% ± 1.1% and 16.7% ± 6.7%, respectively, compared with control eyes (P < 0.05). During treatment, no significant change in systolic or diastolic blood pressure was observed in either species (P > 0.1). Average values for half-life of CKLP1 was 295.3 ± 140.4 min, Cmax, 10.5 ± 1.6 ng/mL, and area under the concentration vs. time curve (AUClast) 5261.4 ± 918.9 ng·min/mL. For levcromakalim, average values of half-life were 96.2 ± 27 min, Cmax 1.2 ± 0.2 ng/mL, and AUClast 281.2 ± 110.8 ng·min/mL. No significant pathology was identified. Conclusions: CKLP1 lowered IOP in hound dogs and African green monkeys with no effect on systemic blood pressure. Ocular topical treatment of CKLP1 showed excellent tolerability even after extended treatment periods.

Understanding the Dual Dilemma of Dry Eye and Glaucoma: An International Review

Glaucoma-related ocular surface disease (G-OSD) is a significant, yet often underdiagnosed, ocular co-morbidity affecting 40% to 59% of glaucoma patients worldwide. Although the use of topical glaucoma medications represents a proven strategy to control the untoward effects of high intraocular pressure, this treatment can profoundly disrupt the homeostasis of the tear film. The cumulative effect of medications, preservatives, and excipients alter underlying cellular structures which results in tear film abnormalities and instability of the ocular surface. Furthermore, these chronic inflammatory changes have been shown to impact efficacy of glaucoma treatment, patient compliance with therapy and overall quality of life. The pathogenesis of G-OSD is multifactorial and involves a vicious self-perpetuating cycle of inflammatory cytokines and proteins. The diagnosis of such disease is based on similar tests used in assessing traditional dry eye, taking into consideration findings specific to this patient population. The hallmark of treatment for these patients is to minimize the ocular surface inflammatory response by choosing glaucoma therapies that spare the ocular surface such as preservative free formulations and initiating dry eye treatment early in the course of care. In summary, glaucoma affects millions of patients around the world and chronic use of topical glaucoma medications may negatively impact the patient's ocular surface, symptoms, and vision. Understanding the pathogenesis of G-OSD, recognizing its risk factors and incorporating diagnostic and therapeutic strategies that restore and maintain ocular surface homeostasis will result in improved care for our patients.

Inflammation in Glaucoma: From the back to the front of the eye, and beyond

The pathophysiology of glaucoma is complex, multifactorial and not completely understood. Elevated intraocular pressure (IOP) and/or impaired retinal blood flow may cause initial optic nerve damage. In addition, age-related oxidative stress in the retina concurrently with chronic mechanical and vascular stress is crucial for the initiation of retinal neurodegeneration. Oxidative stress is closely related to cell senescence, mitochondrial dysfunction, excitotoxicity, and neuroinflammation, which are involved in glaucoma progression. Accumulating evidence from animal glaucoma models and from human ocular samples suggests a dysfunction of the para-inflammation in the retinal ganglion cell layer and the optic nerve head. Moreover, quite similar mechanisms in the anterior chamber could explain the trabecular meshwork dysfunction and the elevated IOP in primary open-angle glaucoma. On the other hand, ocular surface disease due to topical interventions is the most prominent and visible consequence of inflammation in glaucoma, with a negative impact on filtering surgery failure, topical treatment efficacy, and possibly on inflammation in the anterior segment. Consequently, glaucoma appears as an outstanding eye disease where inflammatory changes may be present to various extents and consequences along the eye structure, from the ocular surface to the posterior segment, and the visual pathway. Here we reviewed the inflammatory processes in all ocular structures in glaucoma from the back to the front of the eye and beyond. Our approach was to explain how para-inflammation is necessary to maintain homoeostasis, and to describe abnormal inflammatory findings observed in glaucomatous patients or in animal glaucoma models, supporting the hypothesis of a dysregulation of the inflammatory balance toward a pro-inflammatory phenotype. Possible anti-inflammatory therapeutic approaches in glaucoma are also discussed.

Minimally Invasive Surgery in Mild-to-Moderate Glaucoma Patients in Italy: Is It Time to Change?

Medical therapy is the first treatment choice for most patients with glaucoma; however, in a relevant proportion of patients, intraocular pressure (IOP) reduction is achieved with multi-therapy and/or high therapeutic doses. Conventional surgery is the standard alternative to medical therapy when this is not effective or not tolerated. Recently, selective laser trabeculoplasty (SLT) has been advocated as first-line therapy, and "minimally invasive glaucoma surgery" (MIGS) has been developed as safer and less traumatic surgical intervention for patients with glaucoma. Schlemm's canal surgery has emerged as one of the approaches with the most favorable risk-benefit profile for glaucoma patients in need of cataract surgery. However, despite the promising results, use of MIGS in Italy has been extremely low. We aimed to investigate the reasons of the lower-than-expected use of Schlemm's canal-based MIGS devices in Italy, share our perspective on their potential place in therapy, and give practical suggestions to improve the management of glaucoma patients.

Association between topical beta-blockers and risks of cardiovascular and respiratory disease in patients with glaucoma: a retrospective cohort study

OBJECTIVE

To determine if topical beta-blocker use is associated with increased risks of cardiovascular and respiratory diseases in patients with glaucoma.

SETTING

A retrospective cohort analysis was conducted using the database from Taiwan's National Health Insurance programme.

PARTICIPANTS

In total, 12 336 newly diagnosed patients with glaucoma from January 2000 to December 2010 were included. The patients with glaucoma were subdivided into two cohorts according to whether they used topical beta-blockers or combination drugs (BBCDs).

PRIMARY OUTCOME MEASURES

The study endpoints included pneumonia, acute respiratory failure, stroke and coronary artery disease (CAD). Univariable and multivariable Cox proportional hazards regression models were used to estimate HRs and 95% CIs for the endpoints of both cohorts.

RESULTS

The BBCD cohort had a slightly higher risk of acute respiratory failure (adjusted HRs=1.16, 95% CI 1.00 to 1.34) and lower risk of CAD (aHR=0.93, 95% CI 0.87 to 0.99) than the non-BBCD cohort. Additionally, the risk of stroke was significantly higher in BBCD cohort than in the non-BBCD cohort (aHR=1.39, 95% CI 1.23 to 1.58), especially the ischaemic stroke (aHR=1.44, 95% CI 1.26 to 1.64; aHR=1.44, 98.75% CI 1.21 to 1.71). After considering the multiplicative interaction of age and sex, the BBCD cohort do not have higher risk of all outcomes than the non-BBCD cohort. Further time-dependent regression analysis revealed BBCD cohort had higher risk of acute respiratory failure (aHR=1.17, 95% CI 1.01 to 1.35) and ischaemic stroke (aHR=1.44, 95% CI 1.26 to 1.65) than non-BBCD cohort. However, after considering the multiplicative interaction of age and sex, the BBCD cohort had no significantly higher risk of all outcomes than the non-BBCD cohort.

CONCLUSION

Topical beta-blocker is not associated with increased risks of cardiovascular and respiratory diseases in patients with glaucoma.

Ocular Surface Changes in Prostaglandin Analogue-Treated Patients

Glaucoma is the second leading cause of blindness globally. Reducing intraocular pressure (IOP) has been acknowledged to be the main therapy for glaucoma. Prostaglandin analogues (PGAs) have become the first-line therapy for patients with glaucoma due to their powerful efficacy for lowering (IOP). However, usage of PGAs can also cause several notable side effects, including the changes in ocular surface. The relationship between PGAs and ocular surface changes is complicated and still remains unclear. In the present review, we summarize the recent studies of the effects of PGAs on ocular changes as well as the possible mechanisms that might provide new considerations during clinical medication.

Effects of Preservative on the Meibomian Gland in Glaucoma Patients Treated with Prostaglandin Analogues

This study compared the effect of preservative-containing (PC) and preservative-free (PF) prostaglandin analogue (PGA) formulations on the ocular surface, especially on the meibomian gland (MG) in patients with open-angle glaucoma (OAG). This is a retrospective study of treatment-naïve patients with OAG (n=80) and healthy controls (n=40). OAG patients were randomized into groups using either PC-PGA or PF-PGA for 12 months. All participants underwent ocular surface and MG examinations including their meibum score, meiboscore, and lid margin abnormality score (LAS). Eighty OAG patients were randomized into two groups (n=42 in PC, n=38 in PF). All PGA and control groups showed similar ocular surface and MG parameters at the baseline. Both PC- and PF-PGA groups showed increased meibum scores, meiboscores, and LASs at 12 months compared to the baseline (all p<0.05). At the 12-months visit, PC-PGA group showed severe OSDI, shorter TBUT, greater OSS, and worse MG parameters than those of the other two groups (all p<0.05). In addition, PF-PGA group showed worse meiboscores, meibum scores, and severe OSS scores than those of the control group (all p<0.05). Both PC and PF formulations can cause damage to the MG in patients using PGA. However, PC formulations induced more ocular discomfort, poorer ocular surface, and more severe MG loss compared to PF formulations. Therefore, it would be advisable to use PF formulations in patients with a preexisting or concomitant ocular surface disease or MGD.

The impact of topical intraocular pressure lowering medications on the ocular surface of glaucoma patients: A review

Purpose

To assess the literature on the effects of topical intraocular pressure (IOP)-lowering medications on the ocular surface. Ocular surface assessment in these patients is seldom a priority for most clinicians since the ultimate goal of management is to preserve vision.

Methods

A literature search of articles (English only) on the subject matter was conducted and their findings summarized.

Results

This review assesses the prevalence of dry eye symptoms in glaucoma patients on topical IOP-lowering medications. We extensively reviewed the effects of the preservatives and active ingredients in these medications on the ocular surface. In particular, the effects of benzalkonium chloride (BAK), a widely used preservative, on meibomian glands are explored. Also mentioned in this review is the association between duration of therapy and severity of dry eye symptoms. The role of the pH of medications in the development of ocular surface disease is also reviewed. Finally, we probed the occurrences of ocular allergic reactions with the use of topical IOP-lowering medications.

Conclusions

The preservatives and active agents in most topical glaucoma medications are implicated in the prevalence of ocular surface discomfort. Whilst clinicians involved in glaucoma care are encouraged to assess the ocular surface routinely, further studies are needed to demonstrate the contributions of other physiochemical properties of these medications to the development of ocular surface disease in these patients.

Topical prostaglandin analogues and development of epiretinal membrane

OBJECTIVES

To determine whether patients with glaucoma and epiretinal membrane (ERM) use a greater proportion of prostaglandin analogues (PA) than a control group of patients with glaucoma without ERM.

METHOD

A retrospective study of cases and controls was conducted in order to determine whether patients with glaucoma and ERM used a greater proportion of PA than a control group of patients with glaucoma without ERM. The diagnosis of de ERM was made by clinical examination and optical coherence tomography.

RESULTS

The mean age of the cases was 77 years (SD: 8.68; 95% CI: 74.3-79.4), compared to the controls with 63 years (SD: 16.6; 95% CI: 70.1-78.5). The cases included 50% (n=26) men and 50% women (n=26), whereas in the controls 25.4% (n=16) of the cases were men and 74.6% (n=47) women. PA treatment was used in 59.6% (n=31) and 60.3% (n=38) of the cases and controls, respectively. There was no statistically significant difference in PA use between the 2groups (P=.939).

CONCLUSIONS

In this study, an association between the use of AP and the development of ERM could not be demonstrated.

Effect of brimonidine, an α2 adrenergic agonist, on human meibomian gland epithelial cells

We recently discovered that the anti-glaucoma pharmaceuticals timolol, a β adrenergic antagonist, and pilocarpine, a cholinergic compound, negatively influence the morphology, proliferative capacity and survival of human meibomian gland epithelial cells (HMGECs). We hypothesize that another class of anti-glaucoma drugs, the α2 adrenergic agonists, also acts directly on HMGECs to affect their structure and function. We tested this hypothesis. Immortalized (i) HMGECs were cultured with brimonidine, as well as clonidine (α2 agonist), phenylephrine (α1 agonist), RX821002 (inverse α2 agonist) and MK912 (neutral α2 agonist) for up to 7 days. Cells were counted with a hemocytometer, and evaluated for morphology, signaling pathway activity, protein biomarker expression, and the accumulation of neutral lipids, phospholipids and lysosomes. Our findings demonstrate that brimondine treatment induces a dose-dependent decrease in Akt signaling and proliferation of iHMGECs. In contrast, brimonidine also promotes a dose-dependent differentiation of iHMGECs, including an increase in neutral lipid, phospholipid and lysosome levels. These effects were paralleled by an inhibition of p38 signaling, and duplicated by cellular exposure to clonidine, but not phenylephrine. Brimonidine also enhanced the cellular content of sterol regulatory binding protein-1, a master regulator of lipid synthesis. Of particular interest, the putative α2 antagonists, RX821002 and MK912, did not interfere with brimonidine action, but rather stimulated IHMGEC differentiation. Our results support our hypothesis and demonstrate that α2 adrenergic agonists act directly on iHMGECs. However, these compounds do not elicit an overall negative effect. Rather, the α2 agonists promote the differentiation of iHMGECs.

Influence of Pilocarpine and Timolol on Human Meibomian Gland Epithelial Cells

PURPOSE

Investigators have discovered that topical antiglaucoma drugs may induce meibomian gland dysfunction. This response may contribute to the dry eye disease commonly found in patients with glaucoma taking such medications. We hypothesize that drug action involves a direct effect on human meibomian gland epithelial cells (HMGECs). To test this hypothesis, we examined the influence of the antiglaucoma drugs, pilocarpine and timolol, on the morphology, survival, proliferation, and differentiation of HMGECs.

METHODS

Immortalized (I) HMGECs (n = 2-3 wells/treatment/experiment) were cultured with multiple concentrations of pilocarpine or timolol for up to 7 days. Experiments included positive controls for proliferation (epidermal growth factor and bovine pituitary extract) and differentiation (azithromycin). Cells were enumerated using a hemocytometer and evaluated for morphology, neutral lipid staining, and lysosome accumulation.

RESULTS

Our results demonstrate that pilocarpine and timolol cause a dose-dependent decrease in the survival of IHMGECs. The clinically used concentrations are toxic and lead to cell atrophy, poor adherence, or death. By contrast, drug levels that are known to accumulate within the conjunctiva, adjacent to the meibomian glands, do not influence IHMGEC survival. These latter concentrations also have no effect on IHMGEC proliferation or differentiation, and they do not interfere with the ability of azithromycin to stimulate cellular neutral lipid and lysosome accumulation. This dose of pilocarpine, though, did suppress the epidermal growth factor+bovine pituitary extract-induced proliferation of IHMGECs.

CONCLUSIONS

Our results support our hypothesis and demonstrate that these antiglaucoma drugs, pilocarpine and timolol, have direct effects on HMGECs that may influence their morphology, survival, and proliferative capacity.

Additive Effect of Risk Factors for Trabeculectomy Failure in Glaucoma Patients: A Risk-group From a Cohort Study

PURPOSE OF THE STUDY

The purpose of the study was to assess the role of significant risk factors and develop a risk-group category related to the trabeculectomy (Trab) failure.

MATERIALS AND METHODS

A retrospective cohort study was developed between January 2009 and June 2014. In total, 120 eyes included in this study had a glaucoma diagnosis and undergone to Trab with mitomycin. The main outcome measures were surgical success and failure rate. Multivariate (Cox proportional hazards regression model) analyses were used to examine the predictive value of significant factors. A risk-group category was build based on the number of significant risk factors for patients. The risk group category was tested using the Kaplan-Meier method and log-rank test.

RESULTS

With a median follow-up of 33 months (3 to 72 mo), the complete surgical success in 1, 2, 3, and 4 years was 82%, 63.5%, 52%, and 27.6%, respectively. The probability of freedom from a complete surgical failure was 88%, 84.5%, 78%, and 70% in 1, 2, 3, and 4 years, respectively. Glaucoma type (P=0.008), previous ophthalmic surgery (P=0.04), glaucoma medication use ≥3 years (P=0.010) and 4 glaucoma medication use pre-Trab (P=0.038) were identified as risk factors for surgical failure. The probability of freedom of surgical failure in 3 years was 93%, 83%, and 37.6% (P=0.003), for low (no factors), intermediate (1 to 2 factors), and high-risk group (3 to 4 factors).

CONCLUSIONS

Trab with mitomycin produces satisfactory intraocular pressure control over time. However, several risk factors influence the efficacy of the surgical procedure. Our data show that there seems to exist an additive effect among risk factors with similar pathophysiology.

The signs of ocular-surface disorders after switching from latanoprost to tafluprost/timolol fixed combination: a prospective study

Purpose

To evaluate the ocular-surface safety of a 0.001% benzalkonium chloride-containing tafluprost/timolol fixed combination (TTFC) in patients with primary open-angle glaucoma (POAG) or ocular hypertension who have inadequate intraocular pressure (IOP) control with latanoprost monotherapy.

Methods

This study is a multicenter, prospective, single-arm, open-label clinical study. Patients with POAG or ocular hypertension who have inadequate IOP control with latanoprost monotherapy were considered eligible. After providing informed consent, patients continued latanoprost monotherapy for 12 weeks, followed by a switch to TTFC. We evaluated the extent of ocular-surface damage using superficial punctate keratopathy (SPK) score, tear breakup time (TBUT), hyperemia score, IOP, systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate at 0, 4, and 12 weeks after switching.

Results

A total of 68 patients were enrolled, of whom, 64 patients were included in the final analysis. No significant changes in SPK score, TBUT, or hyperemia score were observed at 4 and 12 weeks compared with week 0. IOP decreased significantly at 4 (13.9±2.5 mmHg) and 12 (14.1±2.5 mmHg) weeks, relative to week 0 (15.3±2.7 mmHg). No significant changes in either SBP or DBP were observed during the study, although patients’ mean heart rate decreased significantly after switching to TTFC. Adverse drug reactions to TTFC occurred in seven patients including two incidences of asthma and one of arrhythmia, and no events were serious.

Conclusion

The ocular-surface safety of TTFC is not significantly different to that of latanoprost. Furthermore, switching from latanoprost to TTFC in patients with insufficient IOP control has additive IOP-lowering effects. TTFC is an effective approach for patients receiving latanoprost monotherapy who require more intensive IOP reduction.

Do Cyclosporine A, an IL-1 Receptor Antagonist, Uridine Triphosphate, Rebamipide, and/or Bimatoprost Regulate Human Meibomian Gland Epithelial Cells?

PURPOSE

Researchers have hypothesized that treatment with cyclosporine A (CyA), interleukin-1 receptor antagonists (IL-1RA; e.g., anakinra), P2Y2 receptor agonists (e.g., uridine triphosphate; UTP), and rebamipide may alleviate human meibomian gland dysfunction (MGD) and/or dry eye disease. Investigators have also proposed that prostaglandin analogues (e.g., bimatoprost) may induce MGD. Our goal was to determine whether these compounds directly influence human meibomian gland epithelial cell (HMGEC) function.

METHODS

Multiple concentrations of each compound were tested for effects on immortalized (I) HMGEC morphology and survival. Nontoxic dosages were used for our studies. Immortalized HMGEC were cultured in the presence of vehicle, CyA, IL-1RA, UTP, rebamipide, or bimatoprost for up to 6 days in various media. Experiments included positive controls for proliferation (epidermal growth factor and bovine pituitary extract), differentiation (azithromycin), and signaling pathway activation (insulin-like growth factor 1). Cells were analyzed for neutral lipid staining, lysosome accumulation, lipid composition, and phosphatidylinositol-3-kinase/Akt (AKT), phosphorylation.

RESULTS

Our findings demonstrate that CyA, IL-1RA, UTP, rebamipide, and bimatoprost had no effect on the proliferation; neutral lipid content; lysosome number; or levels of free cholesterol, triglycerides, or phospholipids in IHMGECs. Cylosporine A, IL-1RA, rebamipide, and bimatoprost significantly reduced the phosphorylation of AKT, as compared to control. Of interest, tested doses of CyA above 8 nM killed the IHMGECs.

CONCLUSIONS

Our results show that CyA, IL-1RA, UTP, rebamipide, and bimatoprost do not influence the proliferation or differentiation of IHMGEC. However, with the exception of UTP, these compounds do decrease the activity of the AKT signaling pathway, which is known to promote cell survival.

Cost-effectiveness of glaucoma management with monotherapy medications in Egypt

Glaucoma is a serious chronic ophthalmic disease since it causes irreversible visual disability if untreated can lead to blindness. Treatment options include medications (classified into five major classes of drugs which are muscarinic cholinergic agonists, alpha-2 adrenergic agonists, beta-1 adrenergic antagonists, prostaglandins [PGs], and carbonic anhydrase inhibitors); use of laser therapy or conventional surgery. Pharmacoeconomic analysis helps in choosing among this variety of treatments. There is a great need for such analysis in Egypt since undergoing of it in different countries or societies may produce different results. This work aimed to compare cost-effectiveness of bimatoprost 0.03% once daily versus brimonidine 0.2% twice daily and timolol 0.5% twice daily as monotherapy treatment in Egyptian patients with open-angle glaucoma or ocular hypertension. Clinical data revealed that all treatments decreased intraocular pressure (IOP) significantly but bimatoprost 0.03% showed the highest efficacy (27.7% decrease in IOP from baseline), while timolol 0.5% reduced IOP by 22.5% then brimonidine 0.2% which decreased IOP by 20.8%. From the cost-effectiveness view, it would be preferable to initiate treatment with timolol in case of absence of any contraindications. PG analog can be used as add-on therapy in low responder patients or as alternative treatment in case of presence of contraindication to use of beta blockers.

Prolonged Ocular Retention of Mucoadhesive Nanoparticle Eye Drop Formulation Enables Treatment of Eye Diseases Using Significantly Reduced Dosage

Eye diseases, such as dry eye syndrome, are commonly treated with eye drop formulations. However, eye drop formulations require frequent dosing with high drug concentrations due to poor ocular surface retention, which leads to poor patient compliance and high risks of side effects. We developed a mucoadhesive nanoparticle eye drop delivery platform to prolong the ocular retention of topical drugs, thus enabling treatment of eye diseases using reduced dosage. Using fluorescent imaging on rabbit eyes, we showed ocular retention of the fluorescent dye delivered through these nanoparticles beyond 24 h while free dyes were mostly cleared from the ocular surface within 3 h after administration. Utilizing the prolonged retention of the nanoparticles, we demonstrated effective treatment of experimentally induced dry eye in mice by delivering cyclosporin A (CsA) bound to this delivery system. The once a week dosing of 0.005 to 0.01% CsA in NP eye drop formulation demonstrated both the elimination of the inflammation signs and the recovery of ocular surface goblet cells after a month. Thrice daily administration of RESTASIS on mice only showed elimination without recovering the ocular surface goblet cells. The mucoadhesive nanoparticle eye drop platform demonstrated prolonged ocular surface retention and effective treatment of dry eye conditions with up to 50- to 100-fold reduction in overall dosage of CsA compared to RESTASIS, which may significantly reduce side effects and, by extending the interdosing interval, improve patient compliance.

ATP sensitive potassium channel openers: A new class of ocular hypotensive agents

ATP sensitive potassium (K_ATP) channels connect the metabolic and energetic state of cells due to their sensitivity to ATP and ADP concentrations. K_ATP channels have been identified in multiple tissues and organs of the body including heart, pancreas, vascular smooth muscles and skeletal muscles. These channels are obligatory hetero-octamers and contain four sulfonylurea (SUR) and four potassium inward rectifier (K_ir) subunits. Based on the particular type of SUR and K_ir present, there are several tissue specific subtypes of K_ATP channels, each with their own unique set of functions. Recently, K_ATP channels have been reported in human and mouse ocular tissues. In ex vivo and in vivo model systems, K_ATP channel openers showed significant ocular hypotensive properties with no appearance of toxic side effects. Additionally, when used in conjunction with known intraocular pressure lowering drugs, an additive effect on IOP reduction was observed. These K_ATP channel openers have also been reported to protect the retinal ganglion cells during ischemic stress and glutamate induced toxicity suggesting a neuroprotective property for this drug class. Medications that are currently used for treating ocular hypertensive diseases like glaucoma do not directly protect the affected retinal cells, are sometimes ineffective and may show significant side effects. In light of this, K_ATP channel openers with both ocular hypotensive and neuroprotective properties, have the potential to develop into a new class of glaucoma therapeutics.

Association between Glaucoma Medication Usage and Dry Eye in Taiwan

PURPOSE

To evaluate the relationship between glaucoma medication usage and dry eye using a Taiwan nationally representative sample.

METHODS

We identified patients with glaucoma diagnoses (ICD-9-CM [International Classification of Diseases, Ninth Revision, Clinical Modification] codes 365) from Taiwan claims data. The study group included 2065 glaucoma patients with newly diagnosed dry eye (ICD-9-CM code 375.15) identified during 2000 and 2011. The control subjects were 8260 glaucoma patients without dry eye who were frequency matched for age, sex, and the year of the index date. The following variables were considered: sex (male/female) and age (12 to 34 years, 35 to 49 years, 50 to 64 years, and ≥ 65 years). Six available glaucoma drugs in Taiwan were analyzed, namely, prostaglandin analog, β-blocker, carbonic anhydrase inhibitor, α-agonists, pilocarpine, and combination drugs. Univariate and multivariate unconditional logistic regressions were used to estimate the effects of glaucoma treatment and comorbidities on the risk of dry eye as indicated by odds ratios (ORs) with 95% confidence intervals (CIs). Further analysis was performed to assess the dose-response effect on the risk of dry eye according to the cumulative number of different types of glaucoma medications used.

RESULTS

Among the 2065 dry eye case patients, 63.3% were female and 48.9% were aged 65 years and older. After adjusting for potential confounding factors, an increased risk of dry eye was observed for all glaucoma medications (prostaglandin analog: adjusted OR, 1.48; 95% CI, 1.30 to 1.69; β-blocker: adjusted OR, 1.57; 95% CI, 1.35 to 1.83; carbonic anhydrase inhibitor: adjusted OR, 1.38; 95% CI, 1.20 to 1.59; pilocarpine: adjusted OR, 1.19; 95% CI, 1.07 to 1.32; combination drugs: adjusted OR, 1.32; 95% CI, 1.09 to 1.58) with the exception of α-agonists. The adjusted OR of having dry eye increased with the number of glaucoma medications used. Similar trends were observed for both female and male subjects.

CONCLUSIONS

An increased number of glaucoma medications used may increase dry eye risk, particularly in subjects who use more than two types of glaucoma medications and in female subjects. Clinicians should be cautious when prescribing medications for glaucoma patients.

Ocular Hypotensive Effects of the ATP-Sensitive Potassium Channel Opener Cromakalim in Human and Murine Experimental Model Systems

Elevated intraocular pressure (IOP) is the most prevalent and only treatable risk factor for glaucoma, a leading cause of irreversible blindness worldwide. Unfortunately, all current therapeutics used to treat elevated IOP and glaucoma have significant and sometimes irreversible side effects necessitating the development of novel compounds. We evaluated the IOP lowering ability of the broad spectrum KATP channel opener cromakalim. Cultured human anterior segments when treated with 2 μM cromakalim showed a decrease in pressure (19.33 ± 2.78 mmHg at 0 hours to 13.22 ± 2.64 mmHg at 24 hours; p<0.001) when compared to vehicle treated controls (15.89 ± 5.33 mmHg at 0 h to 15.56 ± 4.88 mmHg at 24 hours; p = 0.89). In wild-type C57BL/6 mice, cromakalim reduced IOP by 18.75 ± 2.22% compared to vehicle treated contralateral eyes (17.01 ± 0.32 mmHg at 0 hours to 13.82 ± 0.37 mmHg at 24 hours; n = 10, p = 0.002). Cromakalim demonstrated an additive effect when used in conjunction with latanoprost free acid, a common ocular hypotensive drug prescribed to patients with elevated IOP. To examine KATP channel subunit specificity, Kir6.2(-/-) mice were treated with cromakalim, but unlike wild-type animals, no change in IOP was noted. Histologic analysis of treated and control eyes in cultured human anterior segments and in mice showed similar cell numbers and extracellular matrix integrity within the trabecular meshwork, with no disruptions in the inner and outer walls of Schlemm's canal. Together, these studies suggest that cromakalim is a potent ocular hypotensive agent that lowers IOP via activation of Kir6.2 containing KATP channels, its effect is additive when used in combination with the commonly used glaucoma drug latanoprost, and is not toxic to cells and tissues of the aqueous humor outflow pathway, making it a candidate for future therapeutic development.

The Effect of Rebamipide on Ocular Surface Disorders Induced by Latanoprost and Timolol in Glaucoma Patients

Purpose. To examine the efficacy of ophthalmic rebamipide suspensions on ocular surface disorders induced by antiglaucoma eye drops. Patients and Methods. Forty eyes of 40 patients receiving latanoprost (0.005%) and timolol (0.5%) were included in this randomized prospective study. The patients were randomly divided into two groups (n = 20): the rebamipide-treated group and control group. Changes in intraocular pressure, tear film break-up time (TBUT), and corneal epithelial barrier function were evaluated at baseline, 4 weeks, and 8 weeks after rebamipide administration. Furthermore, superficial punctate keratopathy severity was evaluated by scoring the lesion area and density. Results. There was no significant difference in intraocular pressure before and after rebamipide treatment. However, corneal epithelial barrier function improved significantly 4 and 8 weeks after rebamipide treatment. TBUT was partially, but significantly, increased (P = 0.02) 8 weeks after rebamipide treatment, whereas no significant change was observed at 4 weeks. Additionally, a significant decrease in area and density of keratopathy was observed 8 weeks after rebamipide treatment but not at 4 weeks. The control group showed no significant difference compared to baseline. Conclusions. Our data suggests that rebamipide treatment may reduce the occurrence of drug-induced ocular surface disorder.

Ocular surface alterations and topical antiglaucomatous therapy: a review

Ocular Surface Disease (OSD) is prevalent among medically treated patients with glaucoma. This is basically related to three key-points: OSD and glaucoma are both prevalent in elderly and are common comorbidities in the same patient; the role of the active ingredient of the medical antiglaucomatous therapy; the role of the preservative agent of this medical therapy.

Considering the actual state of literature we can state that the active glaucoma agent have a role in OSD, but the main cause seems to be the preservative agent, in particular referring to benzalkonium chloride, BAK.

In the clinical evaluation of dry eye patients there is no actually established gold standard. Since the ocular surface injury not only causes dry eye, red eye, eye itching, photophobia and other discomforts, but also increases the risk of failure of glaucoma surgery in patients, it becomes fundamental a complete and good clinical evaluation of OSD (considering Schirmer’s test, tear breakup time, corneal and conjunctival staining) together with a good evaluation of patients’ quality of life (with validated questionnaires).

Development of complex preparations, preservative-free and/or novel preservative preparations for glaucoma therapy could provide a promising approach in the prevention of ocular surface injuries.