The incidence and time-course of latanoprost-induced iridial pigmentation as a function of eye color

Travoprost Intracameral Implant for Open-Angle Glaucoma or Ocular Hypertension: 12-Month Results of a Randomized, Double-Masked Trial

INTRODUCTION

This prospective, multicenter, randomized, double-masked pivotal phase 3 trial evaluated the efficacy and safety of the travoprost intracameral SE-implant (slow-eluting implant, the intended commercial product) and FE-implant (fast-eluting implant, included primarily for masking purposes) compared to twice-daily (BID) timolol ophthalmic solution, 0.5% in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT).

METHODS

The trial enrolled adult patients with OAG or OHT with an unmedicated mean diurnal intraocular pressure (IOP) of ≥ 21 and unmedicated IOP ≤ 36 mmHg at each diurnal timepoint (8 A.M., 10 A.M., and 4 P.M.) at baseline. The eligible eye of each patient was administered an SE-implant, an FE-implant or had a sham administration procedure. Patients who received an implant were provided placebo eye drops to be administered BID and patients who had the sham procedure were provided timolol eye drops to be administered BID. The primary efficacy endpoint, for which the study was powered, was mean change from baseline IOP at 8 A.M. and 10 A.M. at day 10, week 6, and month 3. Non-inferiority was achieved if the upper 95% confidence interval (CI) on the difference in IOP change from baseline (implant minus timolol) was < 1.5 mmHg at all six timepoints and < 1 mmHg at three or more timepoints. The key secondary endpoint was mean change from baseline IOP at 8 A.M. and 10 A.M. at month 12. Non-inferiority at month 12 was achieved if the upper 95% CI was < 1.5 mmHg at both timepoints. Safety outcomes included treatment-emergent adverse events (TEAEs) and ophthalmic assessments.

RESULTS

A total of 590 patients were enrolled at 45 sites and randomized to one of three treatment groups: 197 SE-implant (the intended commercial product), 200 FE-implant, and 193 timolol. The SE-implant was non-inferior to timolol eye drops in IOP lowering over the first 3 months, and was also non-inferior to timolol at months 6, 9, and 12. The FE-implant was non-inferior to timolol over the first 3 months, and also at months 6 and 9. Of those patients who were on glaucoma medication at screening, a significantly greater proportion of patients in the SE- and FE-implant groups (83.5% and 78.7%, respectively) compared to the timolol group (23.9%) were on fewer topical glaucoma medications at month 12 compared to screening (P < 0.0001, chi-square test). TEAEs, mostly mild, were reported in the study eyes of 39.5% of patients in the SE-implant group, 34.0% of patients in the FE-implant group and 20.1% of patients in the timolol group.

CONCLUSIONS

The SE-travoprost intracameral implant demonstrated non-inferiority to timolol over 12 months whereas the FE-implant demonstrated non-inferiority over 9 months. Both implant models were safe and effective in IOP lowering in patients with OAG or OHT.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT03519386.

Human experience and efficacy of omidenepag isopropyl (Eybelis®; Omlonti®): Discovery to approval of the novel non-prostaglandin EP2-receptor-selective agonist ocular hypotensive drug

More than 75 million people worldwide suffer from ocular hypertension (OHT)-associated retinal and optic nerve degenerative diseases that cause visual impairment and can lead to blindness. In an effort to find novel pharmaceutical therapeutics to combat OHT with reduced side-effect potential, several emerging drug candidates have advanced to human proof-of-concept in recent years. One such compound is a nonprostaglandin (non-PG) EP2-receptor-selective agonist (omidenepag isopropyl ester). Omidenepag (OMD; free acid form) is a novel non-PG that selectively binds to and activates the human EP2-prostglandin receptor (EP2R) with a high affinity (Ki = 3.6 nM) and which potently generates intracellular cAMP in living cells (EC50 = 3.9-8.3 nM). OMD significantly downregulated COL12A1 and COL13A1 mRNAs in human trabecular meshwork (TM) cells, a tissue involved in the pathogenesis of OHT. Omidenepag isopropyl (OMDI) potently and efficaciously lowered intraocular pressure (IOP) in ocular normotensive rabbits, dogs, and monkeys, and also in ocular hypertension (OHT) Cynomolgus monkeys, after a single topical ocular (t.o.) instillation at doses of 0.0001-0.01%. No reduction in IOP-lowering response to OMDI was observed after repeated t.o. dosing with OMDI in dogs and monkeys. Additive IOP reduction to OMDI was noted with brinzolamide, timolol, and brimonidine in rabbits and monkeys. OMDI 0.002% t.o. decreased IOP by stimulating the conventional (TM) and uveoscleral (UVSC) outflow of aqueous humor (AQH) in OHT monkeys. In a Phase-III clinical investigation, 0.002% OMDI (once daily t.o.) reduced IOP by 5-6 mmHg in OHT/primary open-angle glaucoma (POAG) patients (22-34 mmHg baseline IOPs) that was maintained over 12-months. In an additional month-long clinical study, 0.002% OMDI induced IOP-lowering equivalent to that of latanoprost (0.005%), a prostanoid FP-receptor agonist, thus OMDI was noninferior to latanoprost. Additive IOPreduction was also noted in OHT/OAG patients when OMDI (0.002%, once daily t.o.) and timolol (0.05%, twice daily t.o.) were administered. Patients with OHT/POAG who were low responders or nonresponders to latanoprost (0.005%, q.d.; t.o.) experienced significant IOP-lowering (additional approximately 3 mmHg) when they were switched over to OMDI 0.002% (q.d.; t.o.). No systemic or ocular adverse reactions (e.g. iris color changes/deepening of the upper eyelid sulcus/abnormal eyelash growth) were noted after a year-long, once-daily t.o. dosing with 0.002 % OMDI in OHT/POAG patients. However, OMDI caused transient conjunctival hyperemia. These characteristics of OMDI render it a suitable new medication for treating OHT and various types of glaucoma, especially where elevated IOP is implicated.

Recently Approved Drugs for Lowering and Controlling Intraocular Pressure to Reduce Vision Loss in Ocular Hypertensive and Glaucoma Patients

Serious vision loss occurs in patients affected by chronically raised intraocular pressure (IOP), a characteristic of many forms of glaucoma where damage to the optic nerve components causes progressive degeneration of retinal and brain neurons involved in visual perception. While many risk factors abound and have been validated for this glaucomatous optic neuropathy (GON), the major one is ocular hypertension (OHT), which results from the accumulation of excess aqueous humor (AQH) fluid in the anterior chamber of the eye. Millions around the world suffer from this asymptomatic and progressive degenerative eye disease. Since clinical evidence has revealed a strong correlation between the reduction in elevated IOP/OHT and GON progression, many drugs, devices, and surgical techniques have been developed to lower and control IOP. The constant quest for new pharmaceuticals and other modalities with superior therapeutic indices has recently yielded health authority-approved novel drugs with unique pharmacological signatures and mechanism(s) of action and AQH drainage microdevices for effectively and durably treating OHT. A unique nitric oxide-donating conjugate of latanoprost, an FP-receptor prostaglandin (PG; latanoprostene bunod), new rho kinase inhibitors (ripasudil; netarsudil), a novel non-PG EP2-receptor-selective agonist (omidenepag isopropyl), and a form of FP-receptor PG in a slow-release intracameral implant (Durysta) represent the additions to the pharmaceutical toolchest to mitigate the ravages of OHT. Despite these advances, early diagnosis of OHT and glaucoma still lags behind and would benefit from further concerted effort and attention.

The multifunctional human ocular melanocortin system

Immune privilege in the eye involves physical barriers, immune regulation and secreted proteins that together limit the damaging effects of intraocular immune responses and inflammation. The neuropeptide alpha-melanocyte stimulating hormone (α-MSH) normally circulates in the aqueous humour of the anterior chamber and the vitreous fluid, secreted by iris and ciliary epithelium, and retinal pigment epithelium (RPE). α-MSH plays an important role in maintaining ocular immune privilege by helping the development of suppressor immune cells and by activating regulatory T-cells. α-MSH functions by binding to and activating melanocortin receptors (MC1R to MC5R) and receptor accessory proteins (MRAPs) that work in concert with antagonists, otherwise known as the melanocortin system. As well as controlling immune responses and inflammation, a broad range of biological functions is increasingly recognised to be orchestrated by the melanocortin system within ocular tissues. This includes maintaining corneal transparency and immune privilege by limiting corneal (lymph)angiogenesis, sustaining corneal epithelial integrity, protecting corneal endothelium and potentially enhancing corneal graft survival, regulating aqueous tear secretion with implications for dry eye disease, facilitating retinal homeostasis via maintaining blood-retinal barriers, providing neuroprotection in the retina, and controlling abnormal new vessel growth in the choroid and retina. The role of melanocortin signalling in uveal melanocyte melanogenesis however remains unclear compared to its established role in skin melanogenesis. The early application of a melanocortin agonist to downregulate systemic inflammation used adrenocorticotropic hormone (ACTH)-based repository cortisone injection (RCI), but adverse side effects including hypertension, edema, and weight gain, related to increased adrenal gland corticosteroid production, impacted clinical uptake. Compared to ACTH, melanocortin peptides that target MC1R, MC3R, MC4R and/or MC5R, but not adrenal gland MC2R, induce minimal corticosteroid production with fewer amdverse systemic effects. Pharmacological advances in synthesising MCR-specific targeted peptides provide further opportunities for treating ocular (and systemic) inflammatory diseases. Following from these observations and a renewed clinical and pharmacological interest in the diverse biological roles of the melanocortin system, this review highlights the physiological and disease-related involvement of this system within human eye tissues. We also review the emerging benefits and versatility of melanocortin receptor targeted peptides as non-steroidal alternatives for inflammatory eye diseases such as non-infectious uveitis and dry eye disease, and translational applications in promoting ocular homeostasis, for example, in corneal transplantation and diabetic retinopathy.

Ocular Surface Disease and Anti-Glaucoma Medications: Various features, Diagnosis, and Management Guidelines

PURPOSE

Assessment of ocular surface in patients using anti-glaucoma medications (AGM) is rarely a priority for clinicians since glaucoma management targets intraocular pressure and preserves vision. This review summarizes the various adverse effects of topical AGM on the ocular surface and highlights the importance of ocular surface assessment in these patients.

METHODS

A literature search of articles (English only) on the subject matter was conducted focusing on recent articles published in the past 5 years.

RESULTS

The use of multiple anti-glaucoma medications in glaucoma patients increases patients' exposure to the drug and the preservatives present in these medications. Long-term use of these medications has deleterious effects on the conjunctiva, cornea, eyelids, and periocular tissues like trichiasis, entropion, symblepharon, forniceal shortening, punctate keratopathy, non-healing epithelial defects, and pannus. Treatment requires drug withdrawal or substitution by oral or topical non-preserved and less toxic preparations of AGMs. The ocular surface and symptoms can improve if the condition is diagnosed early and after drug withdrawal in over 90% of eyes. However, stopping or changing AGMs can often present with its own unique set of challenges in intra-ocular pressure control which may often need glaucoma surgery in close to 20% of eyes for IOP control.

CONCLUSION

Topical antiglaucoma medications (with their preservatives) can induce severe ocular surface and periorbital changes. Early identification and withdrawal of the offending drug/preservative can help to reverse the changes except in eyes with extensive cicatrization.

In-vivo inhibition of latanoprost induced iridal hyperpigmentation in rabbits- An investigational study

Objectives

To evaluate the inhibitory effects of different concentrations of α-methyl-DL-tyrosine on latanoprost-induced iridal hyperpigmentation in rabbits.

Methods

We investigated 4 groups of rabbits. Both eyes of the pink, red, and blue groups were treated with latanoprost followed by 0.5%, 1%, and 2% α-methyl-DL-tyrosine (inhibitor) in the right eyes respectively and the green group received only inhibitor. We prospectively investigated the irides, estimated quantitatively total melanin contents, and studied any histopathological changes that occurred.

Results

The observers favored hyperpigmentation in the left eyes while in the right eyes they noted a decrease in pigmentation as compared to the baseline. An increase in pigmentation was noted by 93.33% of observers in the left eye of the blue group. A significant difference in the mean melanin contents was noted in the blue group (Right eye = 09.560 μg/g (±0.750), Left eye = 3.730 μg/g (±1.062). There was no evidence of stromal malignant changes, Hemorrhage, mitosis, inflammation, and atypical melanocytes in all specimens. A moderate degree of pigmentation in the left eye of the red group was noted. Mild stromal-free melanin pigment was present in all samples of pink, red and blue groups.

Conclusions

The α-methyl-DL-tyrosine significantly inhibited latanoprost-induced iridal pigmentation without causing any histopathological changes at a 2% dose.

Emerging drugs for the treatment of glaucoma: a review of phase II & III trials

INTRODUCTION

Glaucoma is a progressive optic neuropathy and the leading cause of irreversible vision loss. By 2040, the number of individuals with glaucoma is expected to nearly double. The only known modifiable risk factor for glaucoma is intraocular pressure. Topical medications are often used as first-line therapies. Although there are numerous available treatments, there continues to be a need for the development of new medical therapies due to variable response, intolerable side-effect profiles in some patients, and elevated intraocular pressure refractory to other treatments.

AREAS COVERED

This review will cover glaucoma medications currently undergoing phase II and III of drug development.

EXPERT OPINION

There are numerous drugs currently in development that have demonstrated significant and clinically relevant reduction of intraocular pressure. Differentiating factors include improved tolerability, novel mechanisms of action, multiple mechanisms of action, or superior IOP reduction. However, the availability of generic prostaglandin analogs may limit adoption of these novel compounds as first-line agents, except for certain subgroups of glaucoma patients. Use as adjuvant or second-line therapy appears more likely for the majority of glaucoma patients.

Acquired Iris Heterochromia After Pars Plana Vitrectomy

Describe a case of acquired heterochromia after intraocular surgery. A 63-year-old healthy female patient presented to the eye clinic with rhegmatogenous retinal detachment in her left eye. She underwent uncomplicated pars plana vitrectomy with implantation of posterior chamber intraocular lens. One week after the surgery the patient noticed a change in the color of her operated eye (green instead of blue), she came back to the clinic complaining about her eye color, weeks later her eye color returned back to blue. This case shows a unique presentation of transient acquired heterochromia after intraocular surgery in an adult patient and emphasizes the importance of counseling and reassuring patients regarding the possibility of this event.

Revisiting the Safety of Prostaglandin Analog Eyelash Growth Products

BACKGROUND

The FDA approved bimatoprost ophthalmic solution 0.03% for treatment of eyelash hypotrichosis in 2008. Consumer concern persists regarding potential side effects of this product.

OBJECTIVE

To identify gaps in the safety information associated with the use of prostaglandin eyelash growth products.

MATERIALS AND METHODS

Literature searches were performed using PubMed, Embase, and Nexis Uni databases without restriction to publication date, language, or study setting.

RESULTS

The literature pertaining to bimatoprost for treatment of eyelash hypotrichosis is dominated by industry-sponsored clinical trials. Study design choices create gaps in our understanding of the clinical safety of these products.

CONCLUSION

Because of study design choice, clinical trials of bimatoprost for eyelash growth may have systematically underreported the incidence of drug application discomfort and prostaglandin-associated periorbitopathy. The risk of increased iris pigmentation remains inadequately investigated. Consequently, there is an ongoing need to educate and monitor patients who choose to use these products.

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.

Effects of sustained daily latanoprost application on anterior chamber anatomy and physiology in mice

Latanoprost is a common glaucoma medication. Here, we study longitudinal effects of sustained latanoprost treatment on intraocular pressure (IOP) in C57BL/6J mice, as well as two potential side-effects, changes in iris pigmentation and central corneal thickness (CCT). Male C57BL/6J mice were treated daily for 16 weeks with latanoprost. Control mice were treated on the same schedule with the preservative used with latanoprost, benzalkonium chloride (BAK), or handled, without ocular treatments. IOP and CCT were studied at pre-treatment, 2 "early" time points, and 2 "late" time points; slit-lamp analysis performed at a late time point; and expression of corneal and iridial candidate genes analyzed at the end of the experiment. Latanoprost lowered IOP short, but not long-term. Sustained application of BAK consistently resulted in significant corneal thinning, whereas sustained treatment with latanoprost resulted in smaller and less consistent changes. Neither treatment affected iris pigmentation, corneal matrix metalloprotease expression or iridial pigment-related genes expression. In summary, latanoprost initially lowered IOP in C57BL/6J mice, but became less effective with sustained treatment, likely due to physiological adaptation. These results identify a new resource for studying changes in responsiveness associated with long-term treatment with latanoprost and highlight detrimental effects of commonly used preservative BAK.

Anterior Segment Optical Coherence Tomography Analysis of Iris Morphometric Changes Induced by Prostaglandin Analogues Treatment in Patients with Primary Open Angle Glaucoma or Ocular Hypertension

Background:

The study aimed to evaluate iris thickness changes in patients with Primary Open Angle Glaucoma (POAG) or Ocular Hypertension (OHT) under treatment with Prostaglandin Analogues (PG).

Objectives:

Primary outcome measures were iris thickness at the region of Dilator Muscle Region (DMR) and Sphincter Muscle Region (SMR). DMR/SMR ratio was also evaluated. The secondary outcome was the correlation between PG treatment length and iris parameters.

Methods:

The charts of patients with POAG or OHT who underwent Visante OCT were retrospectively selected. The patients were divided in a group using PG for at least 6 months and a group using hypotensive drops not including PG or alpha-adrenergic agonists. A third group included healthy subjects.

Result:

98 subjects were selected. Patients with POAG or OHT using PG eyedrops showed a significant iris thickness reduction at DMR compared to healthy subjects and to patients using hypotensive eyedrops not containing PG. Significantly higher SMR thickness values were found in PG group compared to both control groups. DMR/SMR ratio significantly reduced in PG group. No correlation was found between PG treatment length and iris parameters.

Conclusion:

The present data indicate that PG treatment induced DMR thickness reduction and an increase in SMR thickness. These changes were not related to the duration of PG exposure.

Beta2 adrenergic receptor silencing change intraocular pressure in New Zealand rabbits

PURPOSE/AIM

Glaucoma consists of a group of progressive optic neuropathies that are characterized by degeneration of the optic nerve and irreversible visual filed loss. Elevated intraocular pressure is the only proven treatable risk factor and commercial products used for glaucoma treatment are focused in lowering intraocular pressure. These drugs can have various undesirable side effects and this invites to look for new strategies. The purpose of this work is to study the use of a siRNA (small interfering RNA) to selectively silence beta2 adrenergic receptors and to see whether it reduces IOP (intraocular pressure).

MATERIAL AND METHODS

Topical instillation of beta2 adrenergic receptors small-interfering RNA (siRNA, 25-250μg) was applied and IOP was measured with a Tonopen XL up to 9 consecutive days. The effect of such siRNA was compared to commercial compounds such as Timoftlol, Trusopt and Xalatan, and it was also analyzed if some anatomical changes occurred by microscopy.

RESULTS

siRNA designed for beta2 adrenergic receptor induced a reduction of intraocular pressure (IOP) of 30±5%, compared to a control (scrambled siRNA). The results in terms of IOP decrease were similar to that found with commercial compounds but a long-lasting hypotensive action was shown by beta2 adrenergic receptor siRNA treatment as compared to commercial drugs. No apparent side effects were observed in the ocular structures.

CONCLUSION

The use of siRNA against the beta2 adrenergic receptors could provide an interesting therapeutic strategy for glaucoma treatment.

Melanogenesis in uveal melanoma cells: Effect of argan oil

The mechanisms underlying cutaneous melanogenesis have been widely studied; however, very little is known about uveal melanogenesis. Melanin is normally produced by uveal melanocytes and gives the color to the iris. A derangement from this normal production may occur, for instance, by iatrogenic events, such as glaucoma therapy with prostaglandins that may enhance cutaneous and iris pigmentation. In this study, we investigated the mechanisms that regulate uveal melanogenesis in human uveal melanoma cells (92.1) and murine cutaneous melanoma cells (B16-F1). In the first part of the study, we compared the effects of known cutaneous pigmenting agents on the B16-F1 and 92.1 cells, showing an opposite response of the two cell lines. Subsequently, using argan oil, a known depigmenting agent for murine cutaneous melanoma cells, on 92.1 cells, we found that in these cells, it also functioned as an inhibitor of melanogenesis and tyrosinase expression. From a molecular perspective, treatment of the 92.1 cells with argan oil decreased melanogenesis-associated transcription factor (MITF) gene expression by inducing MITF phosphorylation at Ser73, thus leading to MITF ubiquitination and disposal. It also led to the downregulation of the extracellular signal-regulated kinase (ERK)1/2 and Akt pathways, also known to be involved in cutaneous melanogenesis, although with an opposing function. Taken together, our data indicate that: ⅰ) some differences exist in the regulation of melanogenesis between cutaneous and uveal melanoma cells; and ⅱ) argan oil exerts a depigmenting effect on 92.1 cells through its action on the ERK1/2 and Akt pathways.

Patient considerations in ocular hypertension: role of bimatoprost ophthalmic solution

Glaucoma is a leading cause of irreversible blindness worldwide. The reduction of intraocular pressure has been well established as an effective treatment to prevent both the development and the progression of all forms of glaucoma. Bimatoprost 0.03% ophthalmic solution, introduced in 2001, is a synthetic prostamide with the unique mechanism of improving both uveoscleral and trabecular outflow. Comparative studies with other pharmacotherapies have shown favorable results for bimatoprost as a potent ocular hypotensive agent that is generally well tolerated. Common side effects include conjunctival hyperemia, eyelash growth, iris pigmentation and periorbital changes. Hyperemia rates were reduced following the introduction of bimatoprost 0.01%. Bimatoprost should be used with caution in those with higher risk of developing ocular inflammation and macular edema. However, the perceived risk of bimatoprost in these patient populations is likely greater than the actual risk observed in practice. Bimatoprost is currently in the center of several clinical trials including its use for dermatologic applications and sustained-release therapies for the treatment of ocular hypertension and glaucoma.

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.

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.

Safety and efficacy of travoprost solution for the treatment of elevated intraocular pressure

Travoprost is a prostaglandin analogue widely used for reducing intraocular pressure (IOP) in patients affected with glaucoma and ocular hypertension. It exerts its ocular hypotensive effect through the prostaglandin FP receptors, located in the ciliary muscle and the trabecular meshwork. Several studies have shown that topical administration of travoprost induces a mean IOP reduction ranging from 25% to 32%, and sustained throughout the 24-hour cycle. When compared with timolol, travoprost is more effective at reducing IOP, while generally no difference has been found in the head-to-head comparison with other prostaglandin analogues. The fixed combination of travoprost and timolol has demonstrated a hypotensive efficacy comparable to the concomitant administration of the two drugs. Recently, a new preservative-free formulation of travoprost 0.004% has been marketed for reducing tolerability-related problems in subjects affected with ocular surface disease. Low rates of topical and systemic adverse reactions, strong ocular hypotensive efficacy, and once-a-day dosing make travoprost a first-line treatment for patients affected with elevated IOP.

Small-interfering RNAs (siRNAs) as a promising tool for ocular therapy

RNA interference (RNAi) can be used to inhibit the expression of specific genes in vitro and in vivo, thereby providing an extremely useful tool for investigating gene function. Progress in the understanding of RNAi-based mechanisms has opened up new perspectives in therapeutics for the treatment of several diseases including ocular disorders. The eye is currently considered a good target for RNAi therapy mainly because it is a confined compartment and, therefore, enables local delivery of small-interfering RNAs (siRNAs) by topical instillation or direct injection. However, delivery strategies that protect the siRNAs from degradation and are suitable for long-term treatment would be help to improve the efficacy of RNAi-based therapies for ocular pathologies. siRNAs targeting critical molecules involved in the pathogenesis of glaucoma, retinitis pigmentosa and neovascular eye diseases (age-related macular degeneration, diabetic retinopathy and corneal neovascularization) have been tested in experimental animal models, and clinical trials have been conducted with some of them. This review provides an update on the progress of RNAi in ocular therapeutics, discussing the advantages and drawbacks of RNAi-based therapeutics compared to previous treatments.

[Pharmacological pseudo-Fuchs]

CASE REPORT

A case of unilateral iridis hyperpigmentation and uveitis due to travoprost is presented.

DISCUSSION

Anterior uveitis is a rare side-effect of travoprost. In this case, heterochromic iris was also presented, which led us to the wrong diagnosis of a Fuchs heterochromic iridocyclitis. The differencial diagnosis along with the associated literature is discussed.

Therapeutic uses of prostaglandin F(2α) analogues in ocular disease and novel synthetic strategies

The pharmacological management of glaucoma and ocular hypertension has significantly changed over the last 18 years with the introduction of PGF2α analogues, more specifically latanoprost (6), travoprost (8), bimatoprost (10) and tafluprost (12). Prostanoids are currently the first-line medicines among ocular antihypertensive drugs in terms of efficacy, safety, patient compliance and medical economy. Their ability to effectively reduce intraocular pressure with once-per-day dosing, ocular tolerability comparable to timolol and general lack of systemic adverse effects have made them the mainstay of pharmacological therapy for glaucoma and ocular hypertension all over the world. The present review reports a novel, convergent and highly diastereoselective method for the synthesis of PGF2α analogues from the structurally advanced prostaglandin phenylsulfone (5Z)-(+)-15 and new ω-chain synthons. The biochemistry, clinical efficacy and side effects of four commercially available PGF2α analogues, currently used as first-line agents for reducing intraocular pressure in patients with glaucoma or ocular hypertension, are also discussed.

Differential activity and clinical utility of latanoprost in glaucoma and ocular hypertension

Background

The purpose of this study was to demonstrate the hypotensive efficacy and tolerability of latanoprost when used as monotherapy and as polytherapy associated with antiglaucomatous medication proven to be ineffective in keeping intraocular pressure under control.

Methods

Three hundred and thirty-seven patients (672 eyes) affected by primary open-angle glaucoma and intraocular hypertension were recruited over a period of 10 years from the Glaucoma Centre, Department of Ophthalmological Sciences, University of Rome “Sapienza”, and treated, subject to informed consent, with latanoprost 0.005% alone or in combination with other ocular hypotensive drugs. The patients were followed during this period at regular intervals, with determination of visual field, fundus oculi, visual acuity, and eventual onset of local and systemic side effects.

Results

Latanoprost used as monotherapy and as polytherapy renders possible optimal and durable control of intraocular pressure in the form of one antiglaucomatous drug because it can substitute for one or more drugs and obtain the same hypotensive effect.

Conclusion

Latanoprost can be described as the ideal hypotensive drug, not only because of its ideal compliance profile (only one daily dose in the evening), excellent hypotensive effect, and, above all, few systemic side effects.

Clinical options for the reduction of elevated intraocular pressure

Elevated IOP in clinical practice is usually seen in glaucoma or ocular hypertension. Glaucoma affects 60 million people worldwide and 8.4 million are bilaterally blind from this chronic disease.1 Options for reducing IOP rely on pharmacological agents, laser treatments and surgery which may be penetrating or non-penetrating. The last twenty years has seen significant changes in all of these strategies. This review aims to cover these clinical options and introduce some of the new technologies currently in development for the clinical lowering of IOP.

A review of the use of latanoprost for glaucoma since its launch

INTRODUCTION

Prostaglandins are increasingly used as first choice treatment for glaucoma because they are highly effective, lack relevant systemic side effects and require just once-daily administration. Latanoprost is an ester prodrug analog of prostaglandin F2α, which reduces intraocular pressure (IOP) by increasing uveoscleral outflow. Latanoprost 0.005% has received European and US approval as the first-line drug for reducing IOP in patients with open-angle glaucoma or ocular hypertension. Following the recent patent expiry for Xalatan®, a number of latanoprost generics have entered the glaucoma market.

AREAS COVERED

This review, achieved through PubMed and Medline research methods, describes the composition, pharmacokinetics, mode of action, efficacy, side effects and safety profile of latanoprost.

EXPERT OPINION

Latanoprost was the first prostaglandin analog introduced in glaucoma management and it dramatically changed the market of the disease thanks to its efficacy and safety. Conjunctival hyperemia, which is commonly found after latanoprost use, is associated with a minor efficacy and duration of trabeculectomy; yet, from the ophthalmologist's perspective, this side effect seems largely counterbalanced by the high efficacy and safety of this compound. It is always advisable to consider the pro-inflammatory mode of action of latanoprost because this may have negative effects in particular patients (i.e., those with uveitis and cystoid macular edema) for whom caution and close follow-up is necessary.

Recent advances in pharmacotherapy of glaucoma

Glaucoma is a slow progressive degeneration of the retinal ganglion cells (RGCs) and the optic nerve axons, leading to irreversible blindness if left undiagnosed and untreated. Although increased intraocular pressure is a major risk factor of glaucoma, other factors include increased glutamate levels, alterations in nitric oxide (NO) metabolism, vascular alterations and oxidative damage caused by reactive oxygen species. Glaucoma is the second leading cause of blindness globally, accounting for 12.3% of the total blindness. Glaucoma has been broadly classified as primary or secondary open-angle or angle-closure glaucoma. The primary goal in management of glaucoma is to prevent the risk factor, especially elevated intraocular pressure (IOP), using medications, laser therapy or conventional surgery. The first-line treatment of glaucoma usually begins with the use of a topical selective or nonselective blocker or a prostaglandin analog. Second-line drugs of choice include alpha-agonists and topical carbonic anhydrase inhibitors. Cholinergic agonists are considered third-line treatment options. When a single therapy is not sufficient to lower the IOP, a combination therapy is indicated. To enhance the patient compliance, drug delivery systems like electronic devices, ocular inserts, tansdermal and mechanical drug delivery systems have been developed. Use of viscoelastic agents in ophthalmic formulations, emulsions and soluble ophthalmic drug inserts (SODI) enhance patience compliance and ocular drug delivery in patients in long-term glaucoma therapy. For patients who do not respond to antiglaucoma medications, laser trabeculoplasty and incisional surgery are recommended. Several nutrients and botanicals hold promise for the treatment of glaucoma, but most studies are preliminary, and larger, controlled studies are required. Future directions for the development of a novel therapy glaucoma may target glutamate inhibition, NMDA receptor blockade, exogenously applied neurotrophins, open channel blockers, antioxidants, protease inhibitors and gene therapy.

Human choroidal melanocyte signal transduction responses to various pharmacological agents: focus on endothelin receptors

PURPOSE

The receptor-coupled signal transduction systems present in isolated human choroidal melanocytes (HCOMs) were investigated.

METHODS

[(3)H]-inositol phosphates ([(3)H]-IPs) generated in the cells were measured by ion-exchange chromatography. cAMP generated in the cells was quantified using an enzyme immunoassay.

RESULTS

Initially, HCOM cells were challenged with a relatively high concentration (e.g., 1 µM-1 mM) of a variety of pharmacological agents in order to determine which functional receptors were present in these cells. Full concentration-response pharmacological studies were subsequently conducted on endothelin receptors. While a number of prostaglandins (PGs) (e.g., PGD(2), PGE(2), PGF(2α), cloprostenol, latanoprost acid, U-46619), histamine, carbachol, bombesin, and arginine-vasopressin were essentially inactive at stimulating the phosphoinositide (PI) hydrolysis response, endothelin-1 (ET-1) potently and efficaciously generated [(3)H]-IPs. Concentration-response studies yielded the following potency (EC(50)) and efficacy (E(max) relative to ET-1) data: ET-1 EC(50) = 3.4 ± 1.4 nM, E(max) = 100%, n = 3; BQ-3020 (ET(B) receptor-selective agonist) EC(50) = 13 ± 4 nM, E(max) = 73 ± 2%, n = 3). The effects of ET-1 on [(3)H]-IPs production were blocked by the ET(B) receptor-selective antagonist, BQ-788 (IC(50) = 10 ± 5 nM, n = 3), while the ET(A) receptor-selective antagonist (BQ-610) was essentially inactive. In the adenylyl cyclase (AC) assay, while isoproterenol (10 µM), ET-1 (1 µM) and PGE(2) (10 µM) stimulated cAMP production, numerous other PGs (e.g., PGD(2), PGF(2α), PGI(2), latanoprost, latanoprost acid, U-46619 and BW245C [all at > 10 µM]) were inactive.

CONCLUSIONS

It is concluded that HCOMs express functionally active ET(B) receptors that mediate the production of [(3)H]-IPs. Additionally, HCOMs generate cAMP in response to ET-1, PGE(2), and isoproterenol. These data may have relevance to the melanogenic activity of HCOM cells.

Effects of common topical antiglaucoma medications on the ocular surface, eyelids and periorbital tissue

Glaucoma affects millions of people around the world. With the baby boom generation aging, the number of people affected by primary open-angle glaucoma in the US is expected to reach 3.3 million by 2020, and about half may not know they have the disease. The treatment of most forms of glaucoma includes the use of topical agents that enhance aqueous humour outflow, reduce aqueous production, or both. Topical intraocular pressure-lowering drugs must penetrate across the tissues of the eye to reach their therapeutic targets. Often, these tissues show the first signs and symptoms of drug toxicity and adverse effects. These include eyelid dermatitis, malpositions, lacrimal system scarring, ocular discomfort upon instillation, tear film instability, conjunctival inflammation, subconjunctival fibrosis, conjunctival epithelium changes, and corneal surface and endothelial impairment. For these reasons, ophthalmologists should evaluate the risks and benefits of ophthalmic medications before initiating therapy, identify the minimum dosages necessary to achieve a therapeutic benefit, and monitor patients for local and systemic adverse effects. Adverse events may be reduced by changing to a different class of topical medication, using corticosteroids, lubricating the eyes frequently, and reducing exposure to preservatives. This in turn can lead to higher levels of adherence to antiglaucoma therapy, improved outcomes and a reduction in the costs associated with long-term glaucoma complications. This article reviews the ocular adverse effects associated with the various classes of topical antiglaucoma drugs, with a particular focus on the ocular surface, eyelids and periorbital tissue.

Intracellular signaling in human iridial fibroblasts and iridial melanocytes in response to prostaglandins, endothelin, isoproterenol, and other pharmacological agents

PURPOSE

The receptor-coupled signal transduction systems present in isolated human iridial fibroblasts (HIF) and in human iridial melanocytes (HIM) were investigated. Cell responsiveness to numerous prostaglandins (PGs), and other compounds of interest, was profiled in order to better understand their involvement in the iridial hyper-pigmentation process observed during treatment of elevated intraocular pressure with FP-receptor against PG analogs.

METHODS

[(3)H]-inositol phosphates ([(3)H]-IPs) generated in the cells were measured by ion-exchange chromatography followed by liquid scintillation spectroscopy. cAMP generated in the cells was quantified using an enzyme immunoassay.

RESULTS

HIF cells exhibited a robust phosphoinositide (PI) hydrolysis response to FP-class PG analogs, such as cloprostenol (potency, EC(50) = 2.4 ± 0.5 nM, n = 5), fluprostenol (EC(50) = 5.3 ± 0.6 nM, n = 3), PGF(2α) (EC(50) = 54 ± 18 nM, n = 5), and latanoprost acid (EC(50) = 121 ± 17 nM, n = 4). Other PGs exhibited the following potencies (EC(50)) for stimulating [(3)H]-IPs accumulation in HIF cells: PGD(2) EC(50) = 327 ± 195 nM, n =3; PGE(2) EC(50) = 550 ± 50 nM, n = 3; and two TP-receptor agonists (I-BOP, EC(50) = 23 ± 8 nM, n = 3; U-46619 EC(50) = 1.1 ± 0.4 µM, n = 3). Endothelin-1 (ET-1) and histamine increased [(3)H]-IPs production in HIF and HIM cells. HIM cells exhibited minimal PI turnover response to cloprostenol, latanoprost acid, latanoprost, PGF(2α), PGE(2), and histamine, but there were robust responses to ET-1 (EC(50) = 4.6 nM, n = 2) and an ET(B)-receptor agonist (BQ-3020, EC(50) = 5 nM, n = 2) that were blocked by an ET(B)-antagonist (BQ-788, IC(50) = 21 ± 6 nM, n = 3). In the adenylyl cyclase activation assay, numerous PGs (1 and 10 µM) stimulated cAMP production in HIF cells yielding the following rank order of efficacy: PGI(2) > PGE(2) > misoprostil > isoproterenol = BW245C > PGD(2) = PGF(2α) = fluprostenol. In HIM cells, PGE(2) (EC(50) = 1.3 ± 0.3 nM) and isoproterenol (β-agonist; EC(50) = 89 ± 13 nM) potently and efficaciously stimulated cAMP production and ICI-118851 (β(2)-antagonist) attenuated the effects of isoproterenol. However, latanoprost acid, latanoprost, ET-1, and BW245C (DP-receptor agonist) were relatively less efficacious than isoproterenol and PGE(2) in HIM cells at stimulating cAMP production.

CONCLUSIONS

These studies have shown that while HIF cells express FP prostaglandin and histamine receptors coupled to phospholipase C to produce [(3)H]-IPs, the HIM cells lack such functionally active FP-receptors. In contrast, HIF and HIM cells express functional ET-1 receptors coupled to [(3)H]-IPs production and both cell-types respond to PGE(2), BW245C, and isoproterenol by generating cAMP. It is concluded that human iridial fibroblasts and melanocytes respond differently to PGs and histamine, but in the same manner to ET-1, isoproterenol and BW245C. This may have relevance to the intercellular communication within the iris relative to the melanogenic processes.

Iris as a reflector for differential absorption low-coherence interferometry to measure glucose level in the anterior chamber

We present a method of glucose concentration detection in the anterior chamber with a differential absorption optical low-coherent interferometry (LCI) technique. Back-reflected light from the iris, passing through the anterior chamber twice, was selectively obtained with the LCI technique. Two light sources, one centered within (1625 nm) and the other centered outside (1310 nm) of a glucose absorption band were used for differential absorption measurement. In the eye model and pig eye experiments, we obtained a resolution glucose level of 26.8 mg∕dL and 69.6 mg∕dL, respectively. This method has a potential application for noninvasive detection of glucose concentration in aqueous humor, which is related to the glucose concentration in blood.

Effectiveness of dorzolamide–timolol (COSOPT) in patients who were treatment naive for open-angle glaucoma or ocular hypertension: the COSOPT first-line study

PURPOSE

The aim of this study was to assess the effectiveness of dorzolamide-timolol (DT) in the management of open-angle glaucoma (OAG) and ocular hypertension.

METHODS

An open-label, 12-week, multicenter, Canadian study was conducted. Patients with untreated OAG or ocular hypertension received DT for 12 weeks to reduce intraocular pressure (IOP). If target IOP was not reached after the first 6-week treatment period, a prostaglandin (PG) (latanoprost) was added for the remaining 6 weeks. Primary outcome measures were changes in IOP from baseline to 6 and 12 weeks of treatment, and secondary outcome measures included the proportion of patients achieving target IOP and the proportion of patients achieving therapeutic response defined as a reduction of 5.0 mmHg or 20% in IOP from baseline. IOP values were the mean of 2 measures taken before and at least 2 h after patients administered the study medication.

RESULTS

A total of 164 patients were enrolled. Mean [standard deviation (SD)] population age was 63.0 (12.3) years and 53.0% of the patients were men. At week 6, the mean (SD) absolute and percent change in IOP for the total population was (-11.1) (4.9) and (-36.4)% (13.9%), respectively, and 92.1% of the patients achieved a reduction in IOP of at least 5 mmHg. Therapeutic target was achieved by 136 (82.9%) patients (DT subgroup) at 6 weeks, whereas 28 (17.1%) patients were changed to a combination therapy of DT and latanoprost [DT plus PG (DT & PG) subgroup]. Between weeks 6 and 12, DT was effective in sustaining the IOP within therapeutic target, whereas addition of latanoprost reduced the IOP of the DT & PG subgroup by an additional 6.3 mmHg or 22.1% (20.1%). At week 12, patients in the DT subgroup experienced a clinically and statistically significant mean (SD) decrease in IOP from a baseline of 12.2 mmHg or 40.4% (11.9%) (P < 0.001), whereas these values corresponded to 13.4 mmHg and 39.7% (15.7%) (P < 0.001), respectively, in the DT & PG subgroup. The proportion of patients who achieved therapeutic response during the entire 12-week study period was over 82%. Treatment-related adverse events (AEs) were reported by 19 (14.0%) patients in the DT subgroup and by 6 (21.4%) patients in the combination subgroup. Eye disorders and nervous system disorders were among the most common treatment-related AEs in both subgroups. No serious AEs were reported during the study period.

CONCLUSION

DT alone and DT in combination with a PG are effective in significantly reducing IOP in patients with untreated OAG or ocular hypertension. The treatment was safe and well tolerated with a low incidence of AEs.

Cytotoxicity of prostaglandin analog eye drops preserved with benzalkonium chloride in multiple corneoconjunctival cell lines

Purpose:

This study evaluated the cytotoxicity of five prostaglandin analog ophthalmic solutions on four ocular surface cell lines, ie, Chang (human conjunctiva), SIRC (rabbit cornea), RC-1 (rabbit cornea), and BCE C/D-1b (bovine cornea).

Methods:

Cell viability was measured by neutral red and MTT assays in cells treated for 10, 30, or 60 minutes with various doses of prostaglandins (undiluted, and 2- and 10-fold dilutions). The number of cell lines with viability ≥50% in the presence of selected dilution of the drug (CVS₅₀) was used for comparison. In addition, 24 cell viability comparisons (four cell lines, two assays, and three exposure times) were made between latanoprost (Xalatan^®) and each other solution at each dose. A comparison between the newly introduced tafluprost (Tapros^®) with 0.01% benzalkonium chloride was also made.

Results:

The order of cell viability determined by CVS₅₀ was Travatan Z^® (travoprost with the SofZia system) > Tapros ≥ Travatan^® (travoprost) = Xalatan > Rescula^® (unoproston). This was consistent with the results of direct comparisons between Xalatan and the other drugs. There was no clear difference in cell viability between Tapros and benzalkonium chloride.

Conclusions:

Use of two assays, multiple cell lines, and various dilutions and exposure times provided a unique evaluation of cytotoxicity among ophthalmic solutions. CVS₅₀ was useful for comparison of the cell viability of the solutions.

Clinical utility and differential effects of prostaglandin analogs in the management of raised intraocular pressure and ocular hypertension

Prostaglandin analogs (PGA) are powerful topical ocular hypotensive agents available for the treatment of elevated intraocular pressure (IOP). Latanoprost 0.005% and travoprost 0.004% are prodrugs and analogs of prostaglandin F2α. Bimatoprost 0.03% is regarded as a prostamide, and debate continues as to whether it is a prodrug. The free acids of all 3 PGAs reduce IOP by enhancing uveoscleral and trabecular outflow via direct effects on ciliary muscle relaxation and remodeling of extracellular matrix. The vast majority of clinical trials demonstrate IOP-lowering superiority of latanoprost, bimatoprost and travoprost compared with timolol 0.5%, brimonidine 0.2%, or dorzolamide 2% monotherapy. Bimatoprost appears to be more efficacious in IOP-lowering compared with latanoprost, with weighted mean difference in IOP reduction documented in one meta-analysis of 2.59% to 5.60% from 1- to 6-months study duration. PGAs reduce IOP further when used as adjunctive therapy. Fixed combinations of latanoprost, bimatoprost or travoprost formulated with timolol 0.5% and administered once daily are superior to monotherapy of its constituent parts. PGA have near absence of systemic side effects, although do have other commonly encountered ocular adverse effects. The adverse effects of PGA, and also those found more frequently with bimatoprost use include ocular hyperemia, eyelash growth, and peri-ocular pigmentary changes. Iris pigmentary change is unique to PGA treatment. Once daily administration and near absence of systemic side effects enhances tolerance and compliance. PGAs are often prescribed as first-line treatment for ocular hypertension and open-angle glaucoma.

Bimatoprost in the treatment of eyelash hypotrichosis

Eyelashes hypotrichosis is a condition indicated by an inadequate amount of eyelashes. Hypertrichosis of eyelashes, characterized by excessive eyelash growth, is a regular phenomenon associated with ophthalmic prostaglandin and prostamide analogs. Recently, the US Food and Drug Administration approved Latisse((R)) (bimatoprost 0.03% solution), identical to the ophthalmic solution for glaucoma treatment, for increasing eyelash length, thickness and darkness in patients with hypotrichosis of the eyelashes. When prostaglandin and prostamide analogs interact with the prostanoid receptors in the hair follicle, this most likely stimulates the resting follicles (telogen phase) to growing follicles (anagen phase). Prostaglandin and prostamide analogs may also prolong the anagen phase of eyelashes, leading to an increase of eyelash length. Although bimatoprost is effective in promoting increased growth of healthy eyelashes and adnexal hairs, its effectiveness in patients with eyelash alopecia areata is debatable and its protective effect is not yet studied in patients with eyelash loss secondary to radiation or chemotherapy. Bimatoprost is generally safe when applied to the base of the eyelashes at the lid margin with minimum side effects. However, other ocular or systemic side effects associated with ophthalmic prostaglandin and prostamide analogs may occur when instilled on the surface of the eye, and patients must be informed and monitored.

Do antiglaucomatous prostaglandins induce melanogenesis in human conjunctiva?: an impression cytology pilot study

PURPOSE

To determine the effect of antiglaucomatous prostaglandin analogs on conjunctival melanogenesis.

METHODS

For this pilot study, 30 glaucomatous patients treated with prostaglandin drops (alone and in association to beta-blockers) and 30 control subjects (15 healthy volunteers and 15 patients treated with beta-blockers) were included in this transversal, single masked, case-control, observational study. Skin complexion, eye color, conjunctival pigmentation, lacrimal tests, and corneal fluorescein staining were evaluated. Immunoreactivity for Tyrosinase was assayed on conjunctival imprints.

RESULTS

Twenty percent of patients treated with prostaglandins and 10% of the control subjects clinically manifested conjunctival pigmentation (P=0.279). Only 4% (8/198) of the conjunctival specimens were positive to Tyrosinase immunostaining, with no statistically significant difference among the groups (P=0.449). In all cases, the proportion of positive cells was below 4%. When compared with subjects having negative specimens, those with positive immunostains did not show any statistically significant difference in skin complexion, eye color or exposure to irritants, and ultraviolet (P>0.05).

CONCLUSIONS

According to our preliminary results, prostaglandin antiglaucomatous analogs do not significantly enhance pigmentation in the superficial layers of the conjunctiva. The existence of the Tyrosinase enzyme in the superficial layers of the conjunctiva suggests that basal melanocytes may transfer their melanogenic apparatus to superficial epithelial cells.

Effects of latanoprost in iris bioidentification

PURPOSE

Bioidentification is becoming increasingly important in everyday life. One of the most widespread methods of bioidentification is based on the structure of the iris. Iris photography has several advantages as an identification method: it is relatively simple and effective; it is non-invasive, and it is comparatively inexpensive. However, some medical conditions may change the appearance of the iris. This paper discusses the effects of latanoprost-induced pigmentation changes in iris bioidentification.

METHODS

The study is based on four extreme cases of latanoprost-induced pigmentation changes. Iris photographs in these patients during treatment are compared with pretreatment photographs. The comparison is carried out with iris recognition software developed by our research group based on the principles of Daugman's well-known IrisCode. The system was evaluated with 595 iris comparisons.

RESULTS

Iris photographs showing latanoprost-induced pigmentation changes were correctly matched with pretreatment photographs of the same irises with an error probability similar to that for matching equivalent pairs of photographs in intact eyes.

CONCLUSIONS

Our results indicate that the pigmentation changes studied do not seem to have a significant effect on the standard identification algorithm.

[Is it possible to combine fixed therapeutic associations?]

The number of fixed associations to treat intraocular pressure has increased over the recent years, to improve patient's treatment adherence. They are generally considered as comparable to the same components administered separately with, in some cases, less side effects. It could thus be appealing to combine fixed associations to reduce these side effects and retain efficacy. However, almost all fixed associations contain timolol, a beta blocker, with a risk of an excessive beta blocking dose and related systemic adverse drug reactions. Several fixed-associations contain a prostaglandin analogue. Their combination would not have a superior efficacy to one fixed combination taken alone. Furthermore, an increased risk or incidence of adverse drug reactions would appear. Specific clinical studies are required before recommending their use in daily clinical practice.

Side effects associated with prostaglandin analog therapy

Topical prostaglandin analogs, which have become first-line therapy in the medical management of glaucoma, have an excellent safety profile with regard to systemic side effects, but are associated with several ocular side effects. Some of these are common, with no apparent serious consequences other than cosmetic, whereas others are much less common but represent potentially sight-threatening side effects. The former group includes conjunctival hyperemia, elongation and darkening of eyelashes, induced iris darkening, and periocular skin pigmentation. The latter group of side effects, which are relatively rare and lack definitive causal relationship to prostaglandin analog therapy, includes iris cysts, cystoid macular edema, anterior uveitis, and reactivation of herpes simplex keratitis. Most of the literature regarding side effects associated with prostaglandin analogs involves the use of latanoprost, probably because it was the first to be studied. There is no evidence, however, aside from less conjunctival hyperemia with latanoprost, that the commercially available prostaglandin analogs differ significantly with regard to side effects.

A study of histopathological features of latanoprost-treated irides with or without darkening compared with non-latanoprost-treated irides

OBJECTIVES

To study the histopathological features of latanoprost-treated irides with or without darkening, compared with non-latanoprost-treated irides.

METHODS

Iridectomy specimens and patient history forms were independently examined by 3 ophthalmic pathologists in a masked fashion. Specimens were evaluated for premalignant changes and for differences in level of pigmentation and degrees of cellularity, inflammation, and vascular abnormalities.

RESULTS

The specimens consisted of 22 latanoprost-treated darkened irides, 35 latanoprost-treated irides without darkening, and 35 non-latanoprost-treated irides. There was a statistically significant decrease in the number of nuclear invaginations and prominent nucleoli in latanoprost-treated darkened irides compared with the other 2 groups (P = .004 and P = .005, respectively). The average thickness and pigmentation of the anterior border layer was greater in the latanoprost-treated darkened irides than in the other 2 groups (P = .03 and P = .02, respectively). The latanoprost-treated darkened irides had increased pigmentation of the stroma (P < .001), stromal fibroblasts (P < .001), melanocytes (P = .005), vascular endothelium (P = .02), and adventitia (P < .001) relative to the other 2 groups.

CONCLUSIONS

There is no histopathological evidence of premalignant changes in latanoprost-treated darkened irides. The latanoprost-induced iris color changes are due to a thickening of the anterior border layer and an increased amount of melanin in the anterior border layer and within the stromal melanocytes.

Increase and decrease of measurements of iris density of glaucoma patients treated with latanoprost over 36 months

PURPOSE

The aim of this study was to measure the density of iris photographs taken over time of patients treated with latanoprost.

METHODS

For 22 patients treated with latanoprost for 36 months, 250 iris photographs were obtained. Photographs were obtained at baseline, and then at 1 month on follow-up and subsequently at 4-month intervals. Photographs were measured in duplicate and masked for time, with a standardized method with red/blue light for density of color.

RESULTS

On visual inspection, 11 irides appeared to show an increase in color or pigment, while 12 showed no change. Eight (8) irides showed a significant, or borderline significant, increasing positive slopes of density measurements over time, while 9 irides showed a significant, or borderline significant, decreasing negative slopes. Six (6) subjects had no significant slope. There was a correspondence between the observations on visual inspection of an increase in color and the analysis of density measurements both by slope and by differences between final minus initial measurements. No leveling off of measurements was observed in almost all of the eyes, which showed increasing trends.

CONCLUSIONS

There is a heterogeneous response to treatment by latanoprost for 36 months in changes over time of red/blue density measurements for iris color.