Corneal alterations induced by topical application of commercial latanoprost, travoprost and bimatoprost in rabbit

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.

The effect of topical bimatoprost on corneal clarity in primary open-angle glaucoma: a longitudinal prospective assessment

PURPOSE

To study the effect of topical bimatoprost on the corneal optical density values using a dual Scheimpflug Placido analysis system.

METHODS

This longitudinal case-control study included 18 patients with newly diagnosed primary open-angle glaucoma who received topical bimatoprost as a first-line treatment and 20 healthy individuals (age and sex-matched controls). Corneal densitometry data were obtained using the dual Scheimpflug analyzer at pre-treatment and 1st, 6th, 12th, 18th months of post-treatment. Repeated measures of ANOVA and Pearson correlation tests were used for statistical analysis.

RESULTS

There were statistically significant differences between pre-treatment and post-treatment 1st and 6th months corneal densitometry values (p < 0.001, p = 0.007, respectively). However, there was no statistically significant difference between the post-treatment 12th and 18th months (p > 0.05). Corneal densitometry values decreased during the 1st month. Intraocular pressure (IOP) differences were statistically significant between baseline and 1 month after treatment (P < 0.001), however not statistically significant between the 1st and 6th, 6th and 12th, 12th and 18th months after treatment (p > 0.05, for all). Corneal densitometry was not correlated with IOP (r = - 0.037, p = 0.44). In the control group, there was no statistically significant difference between baseline and post-baseline 18th-month corneal densitometry measurements (p > 0.05).

CONCLUSIONS

Topical bimatoprost administration might result in a decrease in corneal densitometry measurement. It is of clinical importance that topical bimatoprost administration can affect corneal transparency and cause a possible alteration in corneal properties.

The Effects of Antiglaucoma Ophthalmic Solutions on the Cornea Revealed by a Corneal Electrical Resistance Device

Purpose: We sought to evaluate the effect of antiglaucoma ophthalmic solutions on the cornea with a corneal resistance device (CRD), and to compare the results with those by fluorescein staining. Methods: In 6 rabbit groups (n = 7 each), right eyes were administered latanoprost ophthalmic solution containing 0.02% benzalkonium chloride (BAK); dorzolamide/timolol (1%/0.5%) containing 0.005% BAK; dorzolamide/timolol without BAK; dorzolamide/timolol+latanoprost with 0.02% BAK; 0.005% BAK; or 0.02% BAK to the conjunctival sac 3 × at 15-min intervals. Left (control) eyes were administered saline. Baseline and post-treatment corneal resistance (CR) were measured. The CR ratio = CR before versus after treatment. We evaluated superficial punctate keratitis by fluorescein staining using area and density (AD) grades. Results: In the dorzolamide/timolol-without BAK group, there were no significant difference in the CR ratio between the control and treatment eyes at any time point. In the 0.005%-BAK group at 30 min and the other 4 groups at all time points, the CR ratio differed significantly between the control and treatment eyes (P < 0.05). AD grades were 0 in all control eyes and the dorzolamide/timolol-without BAK and 0.005% BAK treatment eyes. Conclusions: Nonpreservative ophthalmic solutions (and those with low BAK concentrations) do not significantly affect corneal electrical resistance. Eye drop ingredients other than BAK may be involved in altering corneal electrical resistance. CRDs may detect corneal epithelium changes not revealed by fluorescein staining.

Toxicity profiles of fixed-combination eye drops for glaucoma therapy using cultivated human corneal epithelial sheets

PURPOSE

We aimed to investigate the toxicity of 6 fixed-combination drugs for glaucoma therapy using human corneal epithelial sheets (HCES).

STUDY DESIGN

Experimental.

MATERIALS AND METHODS

We used 6 kinds of commercially available fixed-combination drugs: latanoprost/carteolol (LAT/CAR), latanoprost/timolol (LAT/TIM), tafluprost/timolol (TAF/TIM), travoprost/timolol (TRA/TIM), brinzolamide/timolol (BRZ/TIM), and dorzolamide/timolol (DRZ/TIM) including different preservatives. The cell viability and barrier function of the HCES after exposure to the eye drops for 10 or 30 minutes were assessed using the WST-1 assay and transepithelial electrical resistance (TEER) measurements, respectively. The HCES were also evaluated using hematoxylin and eosin (HE) staining and transmission electron microscopy.

RESULTS

The cell viability significantly decreased in the HCES treated with LAT/TIM or DRZ/TIM after 10 and 30 minutes and in those treated with BRZ/TIM after 30 minutes. The barrier function increased significantly in the HCES treated with LAT/CAR. Histologically, the HCES were damaged after treatment with LAT/TIM, BRZ/TIM, or DRZ/TIM for 30 minutes. Transmission electron microscopy indicated narrow intercellular spaces and multiple intercellular junctions in the HCES treated with LAT/CAR, TAF/TIM, or TRA/TIM. The HCES treated with DRZ/TIM, BRZ/TIM, or LAT/TIM contained cytoplasmic vacuoles and collapsed cellular structures.

CONCLUSION

Glaucoma fixed-combination eye drops demonstrated a different toxic effect on the cell viability, barrier function, and morphologic changes of HCES.

Effects of a prostaglandin F2alpha derivative glaucoma drug on EGF expression and E-cadherin expression in a corneal epithelial cell line

Purpose: We examined the effects of travoprost on cell proliferation-related signals and E-cadherin expression in vitro and in situ in order to obtain evidence to support the hypothesis that topical travoprost impairs the integrity of the corneal epithelium.Methods: A human corneal epithelial cell culture was treated with travoprost (0.4 mg/ml) and/or PD168393 (an EGF receptor inhibitor, 10 μM). The culture was then processed for cell proliferation, an mRNA expression analysis of epidermal growth factor (EGF) and E-cadherin, and protein expression analysis of E-cadherin by immunocytochemistry and Western blotting. The eyes of C57/BL6 mice were incubated in serum-free medium plus travoprost (0.4 mg/ml) and/or PD168393 (10 μM). After being cultured for 24 h, the expression patterns of phospho-EGFR, phospho-ERK, E-cadherin, and Ki67 were immunohistochemically examined in paraffin sections.Results: The addition of travoprost up-regulated EGF mRNA expression and cell proliferation in the corneal epithelial cell culture, and this was cancelled by the addition of PD168393. This FP agonist also decreased E-cadherin expression levels in the cell-cell contact zone, and this was cancelled by the addition of PD168393. In the organ culture, the addition of travoprost to the medium up-regulated the expression of phospho-EGFR and phospho-ERK as well as cell proliferation, and down-regulated the expression of E-cadherin in the corneal epithelium, particularly in basal cells, whereas PD168393 reversed these effects.Conclusions: Travoprost activates epithelial cell proliferation by up-regulating an EGF-related signal in association with the suppression of E-cadherin localization in the cell-cell contact zone. Modulation of the EGF signal may be a strategy to minimize the negative impact of this mitogen on reformation of corneal barrier function during epithelial renewal.

Evaluation of corneal epithelial thickness in glaucomatous patients using anterior-segment optical coherence tomography

The corneal epithelium represents one of the main structures that undergo degenerative alterations due to antiglaucomatous therapy. Chronic glaucoma therapy containing benzalkonium chloride induces epithelial cellular changes and inflammatory infiltration that in turn causes ocular surface changes resulting in ocular discomfort. Also, age-related changes can involve the tear film stability and the corneal epithelium surface with reduction of microvilli. The objective of this study is to gain insights about the changes in corneal epithelium in glaucomatous patients divided according to age, type and duration of therapy using anterior-segment optical coherence tomography (AS-OCT). This study evaluated a total of 81 eyes of 42 patients for whom corneal epithelium thickness (CET) was measured in different sectors of the cornea. Our results showed no significant differences in CET among patients divided according to type and duration of treatment, while younger patients showed a thinner CET in comparison with older patients. AS-OCT results demonstrated that the physiological age-related alterations contributed to corneal epithelium changes in patients undergo chronic antiglaucoma therapy.

0.005% Preservative-Free Latanoprost Induces Dry Eye-Like Ocular Surface Damage via Promotion of Inflammation in Mice

Purpose

To investigate the side effects of preservative-free 0.005% latanoprost on the murine ocular surface.

Methods

We applied 0.005% latanoprost or vehicle in mice in two patterns for 14 to 28 days. Tear production was measured by phenol red cotton test, and corneal epithelial barrier function was assessed by Oregon-green-dextran (OGD) staining. Periodic acid-Schiff (PAS) staining was used to quantify conjunctival goblet cells (GCs). The expression of matrix metalloproteinase (MMP)-3 and -9, occludin-1 and zonula occludens (ZO)-1 in corneal epithelium was assessed by immunofluorescent staining and/or quantitative real-time PCR (qRT-PCR). Inflammation in conjunctiva was assessed by activation of P38 and NF-κB, infiltration of CD4+ T cells, and production inflammatory cytokines including TNF-α, IL-1β, IFN-γ, IL-17A, and IL-13. Apoptosis in ocular surface was assessed by TUNEL and immunofluorescent staining for activated caspase-3 and -8. Cell viability assay was performed in human corneal epithelial cells.

Results

Topical latanoprost treatment decreased tear production, induced conjunctival GC loss, disrupted the corneal epithelial barrier, and promoted cell apoptosis in the ocular surface. Topical latanoprost treatment increased the expression of MMP-3 and -9, and decreased the expression of ZO-1 and occludin-1 in the corneal epithelium. Topical application of latanoprost promoted activation of P38-NF-κB signaling and production of TNF-α and IL-1β in conjunctiva. Topical application of latanoprost increased CD4+ T cells infiltration, with increased production of IFN-γ and IL-17A and decreased production of IL-13 in conjunctiva.

Conclusion

0.005% latanoprost induced dry eye-like ocular surface damage via promotion of inflammation in mice.

Anterior-Segment Optical Coherence Tomography and Scanning Electron Microscopy to Evaluate Corneal Epithelial Changes in Patients Undergoing Glaucoma Therapy

PURPOSE

To measure corneal epithelial thickness (CET) in patients with glaucoma using anterior-segment optical coherence tomography and to evaluate CET changes in relation to corneal epithelial microvilli analyzed by scanning electron microscopy (SEM).

METHODS

Twenty-two eyes (16 patients) being treated with preservative-containing topical medications and 12 normal eyes underwent anterior-segment optical coherence tomography imaging using RTVue-100. The CET maps generated corresponded to a 6-mm diameter area of cornea that was divided into 17 sectors. We compared the CETs of each sector obtained in the glaucomatous group with those obtained in the control group.

RESULTS

Glaucomatous eyes were divided into 2 groups based on the number of microvilli on SEM: group 1 (6 eyes) = grades 1 and 2 at SEM (range: 500-3000) and group 2 (10 eyes) = grades 3 and 4 at SEM (range: 0-500). Four CET sectors were significantly thinner in group 1 than in normal eyes: central (P = 0.012), superior (P = 0.005), temporal paracentral (P = 0.003), and temporal midperipheral (P = 0.023). No significant differences were observed between group 2 and normal eyes. CET sectors were significantly thinner in group 1 than in group 2 only in the superior (P = 0.024) and superior-temporal paracentral (P = 0.020) sectors. CET progressively increased in patients with glaucoma as the number of corneal epithelial microvilli decreased.

CONCLUSIONS

CET and corneal epithelial microvilli are new parameters with which to evaluate early stages of corneal epithelial changes during glaucoma therapy. In advanced stages of corneal epithelial damage, SEM evaluation reveals ultrastructural epithelial changes that may not be observed on CET measurements.

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.

Reduction in Ocular Hypotensive Eyedrops by Ab Interno Trabeculotomy Improves Not Only Ocular Surface Condition But Also Quality of Vision

Purpose

To investigate the effect of ab interno trabeculotomy using the Trabectome surgical system on tear film stability and functional visual acuity (FVA).

Patients and Methods

Adult glaucoma patients who underwent Trabectome surgery alone or Trabectome surgery combined with phacoemulsification with intraocular lens insertion were included in this study. Corneal epithelial defects, tear film breakup time (TBUT), tear meniscus height, tear film spreading grade, tear interferometry grade, and FVA were assessed before and after surgery in addition to routine ophthalmic examinations. Changes in ocular surface conditions and visual acuity as a result of the Trabectome surgery were investigated.

Results

Thirty eyes of 22 patients with a mean age of 72.2 ± 7.9 years, including 8 males and 14 females, were enrolled. The Trabectome surgery significantly reduced the intraocular pressure (IOP) from 20.3 ± 5.2 to 15.0 ± 3.3 mmHg (P < 0.001) and the number of different types of ocular hypotensive eyedrops used from 3.2 ± 0.7 to 1.1 ± 0.7 types (P < 0.001). The surgery significantly improved corneal epithelial defects, the tear spreading grade, the tear interferometry grade, and FVA. The surgery also improved the visual maintenance ratio among all enrolled patients, including those who underwent Trabectome surgery only.

Conclusion

Trabectome surgery may be beneficial not only for IOP reduction but also for improving ocular surface conditions and FVA.

The Role of the P2X7 Receptor in Ocular Stresses: A Potential Therapeutic Target

The P2X7 receptor is expressed in both anterior and posterior segments of the eyeball. In the ocular surface, the P2X7 receptor is activated in case of external aggressions: preservatives and surfactants induce the activation of P2X7 receptors, leading to either apoptosis, inflammation, or cell proliferation. In the retina, the key endogenous actors of age-related macular degeneration, diabetic retinopathy, and glaucoma act through P2X7 receptors’ activation and/or upregulation of P2X7 receptors’ expression. Different therapeutic strategies aimed at the P2X7 receptor exist. P2X7 receptor antagonists, such as divalent cations and Brilliant Blue G (BBG) could be used to target either the ocular surface or the retina, as long as polyunsaturated fatty acids may exert their effects through the disruption of plasma membrane lipid rafts or saffron that reduces the response evoked by P2X7 receptor stimulation. Treatments against P2X7 receptor activation are proposed by using either eye drops or food supplements.

Ocular surface toxicity from glaucoma topical medications and associated preservatives such as benzalkonium chloride (BAK)

INTRODUCTION

This review discusses the evidence concerning the effect of topical medications and their preservatives on the ocular surface in glaucoma patients. The role of topical anti-glaucoma medication remains critical in the management of chronic glaucoma worldwide but the beneficial effects of treatment are counterbalanced by the adverse effects of corneal and conjunctival toxicity. Areas covered: This article covers the effect of topical ocular drops and preservatives, particularly benzalkonium chloride, on the cornea and conjunctiva. Both basic science and clinical evidence will be presented. The first part reviews the relationship between ocular surface disease and benzalkonium chloride and the evidence from non-benzalkonium chloride preserved drops. The second part discusses the effects of benzalkonium chloride on the histopathology of the conjunctiva and its impact on clinical care as well as quality of life. Expert opinion: Topical anti-glaucoma medication will continue to be used in the management of this blinding disease for the foreseeable future. Treatment outcomes will benefit from minimized exposure to benzalkonium chloride. The development of alternative preservatives, preservative-free topical options, and non-drop therapeutics such as drug-eluting systems for the delivery of ocular medications, will be very helpful in the care of glaucoma patients.

Clinical features and in vivo confocal microscopy assessment in 12 patients with ocular cicatricial pemphigoid

AIM

To describe the clinical features and microstructural characteristics assessed by in vivo confocal microscopy (IVCM) in patients with ocular cicatricial pemphigoid (OCP).

METHODS

A descriptive, uncontrolled case series study. Patients diagnosed with OCP were examined by clinical history, slit-lamp biomicroscopy features and IVCM images. The results of direct immunofluorescence (DIF) biopsies and indirect immunofluorescence (IIF) were also recorded. Local and systemic immunosuppressive therapy were administered and adjusted according to response.

RESULTS

A total of 12 consecutive OCP patients (7 male, 5 female; mean age 60.42±10.39y) were recruited. All patients exhibited bilateral progressive conjunctival scarring and recurrent chronic conjunctivitis was the most frequent clinical pattern. The mean duration of symptoms prior to diagnosis of OCP was 2.95±2.85y (range: 5mo to 10y). The Foster classification varied from stage I to IV and 20 eyes (83%) were within or greater than Foster stage III on presentation. Two of the 12 patients (17%) demonstrated positive DIF; 3 of the 12 (25%) patients reported positive IIF. The mean duration of the follow-up period was 20.17±11.88mo (range: 6 to 48mo). IVCM showed variable degrees of abnormality in the conjuctiva-cornea and conjuctival scarring was detected in all the involved eyes. Corneal stromal cell activation and dendritic cell infiltration presented as ocular surface inflammation, ocular surface keratinization along with the destroyed Vogt palisades was noted in eyes with potential limbal stem cell deficiency. After treatment, remission of ocular surface inflammation was achieved in all the patients, 18 eyes (75%) remained stable, 6 eyes (25%) had recurrent conjunctivitis and cicatrization in 2 eyes (8%) was progressing.

CONCLUSION

As an autoimmune disease, OCP manifests as variable degrees of clinical and laboratory abnormalities with both local and systemic immunosuppressive treatment playing important roles in disease therapy. IVCM can be as a valuable non-invasive technique to assess ocular surface changes in a cellular level with a potential value for providing diagnostic evidence and monitoring therapeutic effects during follow-up.