Central Corneal Thickness During Treatment With Travoprost 0.004% in Glaucoma Patients

How latanoprost changed glaucoma management

Glaucoma is currently considered one of the leading causes of severe visual impairment and blindness worldwide. Topical medical therapy represents the treatment of choice for many glaucoma patients. Introduction of latanoprost, 25 years ago, with an entirely new mechanism of action from that of the antiglaucoma drugs used up to that time was a very important milestone. Since then, due mainly to their efficacy, limited systemic side effects and once daily dosing, prostaglandin analogues (PGAs) have become as the first-choice treatment for primary open-angle glaucoma. PGAs are in general terms well tolerated, although they are associated with several mild to moderate ocular and periocular adverse events. Among them, conjunctival hyperemia, eyelash changes, eyelid pigmentation, iris pigmentation and hypertrichosis around the eyes are the most prevalent. The objective of this paper is to review the role of PGAs in the treatment of glaucoma over the 25 years since the launch of Latanoprost and their impact on clinical practice outcomes.

Effects of topical prostaglandin therapy on corneal layers thickness in primary open-angle glaucoma patients using anterior segment optical coherence tomography

PURPOSE

To evaluate the effects of latanoprost, bimatoprost, and travoprost eye drops and their preservatives on each corneal layer thickness in patients with primary open-angle glaucoma (POAG).

METHODS

We retrospectively analyzed 79 eyes of 79 patients with POAG who were receiving prostaglandin therapy. Patients were divided into three subgroups according to monotherapy with latanoprost, bimatoprost, and travoprost during a mean of 43.14 ± 19.12 months follow-up period. In addition, the central corneal epithelial thickness (CET), central corneal stromal thickness (CST), and total central corneal thickness (CCT) were measured by anterior segment optical coherence tomography (AS-OCT) at baseline and every six months after treatment initiation at each visit between 9 and 12 o'clock in the morning. Furthermore, intraocular pressure (IOP) was measured with Goldmann applanation tonometry (GAT) after AS-OCT measurements at each visit.

RESULTS

All three groups were not significantly different in age, gender, follow-up period, and mean intraocular pressure values (p > 0.05 for all). The reduction of CCT in the latanoprost, bimatoprost, and travoprost groups was 6.53 ± 3.17, 18.59 ± 8.42, and 10.1 ± 1.13 µm, respectively. The decrease in CST values was 4.65 ± 1.54, 15.84 ± 7.47, 9.69 ± 1.45 µm, and CET values were 1.88 ± 1.66, 2.75 ± 0.73, 0.41 ± 0.54 µm in all groups, respectively. A statistically significant thinning was observed in all corneal layers (p < 0.05) except the CST values in the latanoprost group and CET values in the travoprost group. However, no significant difference was found in the average reduction of CET, CST, and CCT values among the three groups (p > 0.05).

CONCLUSION

Topical treatment with latanoprost, bimatoprost, and travoprost affects each layer of the cornea separately according to the active and protective substances contained in these eye drops. On the other hand, the thinning effect on the corneal layers was similar in these three drugs because there was no significant difference between the three groups in the total amount of thinning of the corneal layers during the follow-up period.

Effect of Topical Prostaglandin Analogue Therapy on Central Corneal Thickness: A Systematic Review

To investigate whether prostaglandin analogue (PGA) eyedrops have a significant effect on central corneal thickness (CCT), we conducted a systematic search of literature published from 2000 to 2021. Among the studies conducted on topical PGA therapy in open-angle glaucoma or ocular hypertension patients over 18 years old, prospective studies with CCT change as an outcome were included. A single-arm meta-analysis was conducted to assess the overall effect on CCT, and subgroup analysis according to exposure time of PGA eyedrops was also performed. We counted the number of articles that reported on severe events (CCT reduction of 25 μm or more) and obtained their proportion. The methodological quality was assessed by the McHarm tool. Twenty-two reports of prospective studies were selected. The results of the single-arm meta-analysis showed very high heterogeneity. Still, in subgroup analysis, when PGA was used for more than 6 months, heterogeneity was low, and a significant decrease in CCT was observed. Severe events were reported in two reports and occurred in 3.8% to 14.8% of participants. PGA eyedrop use may cause a clinically significant CCT decrease, requiring CCT follow-up.

The Effect of Prostaglandin Analogs on Central Corneal Thickness of Patients with Glaucoma or Ocular Hypertension: A Systematic Review

BACKGROUND

Prostaglandin analogs (PGAs) are first-line antiglaucoma agents that appear to either decrease or increase central cornea thickness (CCT), creating controversy regarding the benefits of PGAs in treating CCT.

PURPOSE

We performed the first meta-analysis of observational studies to evaluate the effects of PGAs on CCT in patients with glaucoma or ocular hypertension (OHT).

METHODS

This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. A literature search was performed of the PubMed, Embase, Cochrane Library, System for Information on Grey Literature in Europe (Open Grey), and ClinicalTrials.gov databases and the references of retrieved studies. Only observational studies were included in the meta-analysis. The final CCT of patients and 95% confidence interval (CI) of each study were extracted. Study quality was assessed using the Newcastle-Ottawa Scale (NOS) and the Agency for Healthcare Research and Quality (AHRQ). A fixed-effects model was used to calculate the weighted mean difference (WMD) and 95% CI. Subgroup analyses based on several stratified factors such as public bias (Begg's test) and sensitivity analyses were performed.

RESULTS

Five cohort, 5 case-control, and three cross-sectional studies including 2,722 subjects were included. The pooled effect of all thirteen studies showed that PGAs reduced the CCT of patients with glaucoma or OHT slightly but significantly (WMD = -9.37; 95% CI [-12.18, -6.57]; p = 0.00; I2 = 45.5%). Significant effects were also observed in all three study designs: cohort (WMD = -5.17; 95% CI [-9.52, -0.82]), case-control (WMD = -15.31; 95% CI [-22.66, -7.97]), and cross-sectional (WMD = -8.65; 95% CI [-17.30, -0.01]). In addition, subgroup analysis of exposure time showed the effect of PGAs to be more obvious in the first (WMD = -5.81; 95% CI [-9.49, -2.14]) and second (WMD = -13.73; 95% CI [-20.19, -7.28]) years.

CONCLUSIONS

The pooled effects of previously reported studies suggest that PGA use can reduce the CCT of patients with glaucoma or OHT slightly but significantly, with this effect more pronounced in the first 2 years. These findings suggest that clinicians must closely monitor changes in CCT in the first 2 years of PGA use to identify cases of intraocular pressure misestimation and the efficacy of PGAs.

Effect of travoprost, latanoprost and bimatoprost PGF2α treatments on the biomechanical properties of in-vivo rabbit cornea

Prostaglandin F2α analogues (PGF2α), one of the most commonly prescribed classes of hypotensive agents, could decrease collagen fibril density and remodel the extracellular matrix in cornea. We hypothesized that PGF2α's would induce corneal softening, reduce the accuracy of intraocular pressure (IOP) measurement and lead to uncertainty in the effectiveness of the therapy. We determined the stress-strain behavior of rabbit cornea after PGF2α usage and evaluated the effect of biomechanical changes associated with PGF2α treatment on IOP measurements by Goldmann Applanation Tonometry (GAT). The tangent modulus decreased after PGF2α treatment, while the stromal interfibrillar spacing increased. PGF2α was shown to also affect the lateral eye with lower effect, which did not undergo direct eyedrop treatment. Significant decreases in the numerical predictions of GAT-IOP were predicted in all treated groups relative to control groups. Different PGF2α's (travoprost, latanoprost and bimatoprost) were associated with different extents of reduction in tissue stiffness and changes in corneal microstructure. PGF2α-induced changes in corneal mechanical properties could reduce the accuracy of IOP measurement and may cause an overestimation of the effect of PGF2α in lowering IOP, possibly leading to uncertainties in glaucoma management.

A new look at the safety and tolerability of prostaglandin analogue eyedrops in glaucoma and ocular hypertension

INTRODUCTION

In the last 25 years, topical prostaglandin analogues (PGAs) have emerged to become first line and first choice therapeutic options in the management of glaucoma and ocular hypertension (OHT). Although the short-term efficacy and safety of PGAs has been extensively investigated, less is known about their long term safety and tolerability. This gap in current knowledge is clinically relevant, because treatment-related adverse events and long-term tolerability issues are key determinants of the overall success of long-term therapy and the final outcome of a lifelong, symptomless disease like glaucoma.

AREAS COVERED

We include selected evidence pertaining to the safety and tolerability of available and emerging PGA formulations. We also outline PGA formulations with different concentrations of the active ingredient, different preservatives, and preservative-free (PF) options.

EXPERT OPINION

Undoubtedly PGAs will continue to play a major role in the medical therapy of glaucoma and OHT. Despite extensive literature and prolonged clinical experience with these agents worldwide, a number of areas that warrant further research have been identified in the present review. Recently launched novel PGAs, or those still in development offer new opportunities and future challenges.

Central Corneal Thickness Among Filipino Patients in an Ambulatory Eye Surgery Center Using Anterior Segment Optical Coherence Tomography

Objective

The purpose of the study was to determine the central corneal thickness (CCT) among Filipino patients that may contribute to different glaucoma diagnosis using the anterior segment optical coherence tomography in an ambulatory eye surgery center.

Methods

A single-center retrospective, cross-sectional study design including 1232 eyes of 641 patients of the Asian Eye Institute, Makati, Philippines from January 2019 to December 2019 who had their CCT measured with Visante anterior segment optical coherence tomography (AS-OCT). CCT was correlated with age, sex, presence of diabetes and/or hypertension, and glaucoma diagnosis.

Results

Among 641 patients who had their CCT measured by Visante AS-OCT, 723 eyes of 369 patients were included. Nearly half of the study population were normal or glaucoma suspects. The mean CCT among Filipino patients was 535.59 ± 34.06 µm. Ocular hypertensive patients had the thickest CCT, while normal tension glaucoma patients had the thinnest CCT. After adjusting for multiple variables, CCT had a direct relationship with the presence of diabetes, IOP level and the diagnosis of ocular hypertension, while inverse relationship with age. Most of the patients presenting with angle closure glaucoma were females aged 60 and above.

Conclusion

Visante AS-OCT is a non-contact and non-aerosol generating instrument allaying the fear of disease transmission from contact or aerosolization of tears. Our study confirms similar relationships of CCT with age, presence of diabetes, IOP level, and diagnosis of ocular hypertension or normal tension glaucoma among Filipino patients with the available literature from other ethnicities.

Biomechanical Effects of Two Forms of PGF2α on Ex-vivo Rabbit Cornea

PURPOSE

To investigate the biomechanical effects of two synthetic prostaglandin F2α analogues (PGF2α), namely Travoprost and Tafluprost, on the ex-vivo rabbit cornea.

MATERIALS AND METHODS

Ninety-six eyes of 48 Japanese white rabbits were divided into 3 equal groups randomly; the Travoprost treated group (Tra), the Tafluprost treated group (Taf) and the control group (Co). Eyes in Tra and Taf groups were preserved in storage medium for 10 days with 1:10 Travoprost and Tafluprost diluents, respectively; while the Co eyes were preserved in a similar but PGF2α-free medium. Twenty-four corneas of each group were tested under inflation conditions with up to 30 mmHg posterior pressure. The pressure-deformation data obtained experimentally were used in an inverse analysis process to derive the stress-strain behavior of the tissue, using which the tangent modulus, a direct measure of the tissue's material stiffness, was calculated. The remaining eight specimens of each group were analyzed using electron microscopy for fibril diameter and interfibrillar spacing.

RESULTS

Although the central corneal thickness increased significantly in the three groups after storage (p < .01), it was similar in all groups both before (p = .598) and after storage (p = .181). After treatment with Travoprost and Tafluprost, the corneas exhibited lower tangent modulus (by 29.2% and 29.8%, respectively, at 6 kPa stress) and larger stromal interfibril spacing (by 21.9% and 23.6%) compared with the control group. There was no significant change in fibril diameter with either Travoprost or Tafluprost treatment (p = .769).

CONCLUSIONS

The results demonstrated significant reductions in tangent modulus and increases in interfibrillar spacing, which were of similar magnitudes, with the application of two different forms of PGF2α.

Effect of Manual Upper Eyelid Elevation on Intraocular Pressure Measurement by Four Different Tonometers

SIGNIFICANCE

This study is the first to show that the manual upper eyelid elevation (manual UEE) that is commonly used to prevent disruption of the IOP measurement due to blinking or upper eyelid contact with the tip of the tonometer does not affect the IOP values.

PURPOSE

We investigated whether manual UEE affects the IOP readings using three rebound tonometers (Icare TA01i, Icare PRO, and Icare ic100) and Goldmann applanation tonometry (GAT).

METHODS

One eye was measured for 101 patients (56 eyes of primary open-angle glaucoma patients and 45 healthy subjects). The IOPs were measured without and with manual UEE. Each IOP was measured twice; the measurement order using the tonometers was randomly selected. In addition, palpebral fissure height (distance between the upper and lower eyelids) was measured.

RESULTS

The IOPs without manual UEE were 12.1 ± 2.9, 13.3 ± 2.7, 11.7 ± 2.9, and 16.0 ± 3.2 mmHg (Icare TA01i, Icare PRO, Icare ic100, and GAT), and those with manual UEE were 12.3 ± 3.0, 13.3 ± 2.8, 11.7 ± 2.9, and 16.0 ± 3.3, respectively. No significant difference was found between the IOP without and with manual UEE (IOP difference; all, P > .50; paired t test). Multiple linear regression analyses revealed that palpebral fissure height did not affect IOP difference for any of the tonometers.

CONCLUSIONS

Simple manual UEE when measuring the IOP has little effect on the IOP obtained using all current rebound tonometers and GAT.

Central Corneal Thickness Variances Among Different Asian Ethnicities in Glaucoma and Nonglaucoma Patients

OBJECTIVE

To compare the central corneal thickness (CCT) between different ethnicities and particularly Asian subethnic groups that may contribute to the different glaucoma diagnoses using the optical low-coherence reflectometry technique.

METHODS

A retrospective study of 6 years including 1512 eyes of 929 patients of the Beckman vision center, University of California, San Francisco from 2011 to 2017 had their biometric parameters, including CCT, measured with the Lenstar. Patients were categorized into African Americans, Caucasians, Hispanics, Pacific Islanders, and Asians. Asians were further subcategorized into Chinese, Vietnamese, Koreans, Filipinos, and Japanese.

RESULTS

Among 1356 patients who had their CCT measured by Lenstar from 2011 to 2017, 1512 eyes of 929 patients were included. The study population included 462 Caucasians (52.96%), 60 African Americans (6.46%), 92 Hispanics (9.9%), 32 Pacific Islanders (3.44%), 130 Chinese (13.99%), 52 Filipinos (5.6%), 37 Vietnamese (3.98%), 34 Koreans (3.66%), and 30 Japanese (3.23%). African Americans had the thinnest CCT with a mean of 518.62±40.3 followed by Asians with a mean of 539.29±34.1. Among the Asian study sample, the Chinese had the thinnest CCT with a mean of 537.66±32.5. CCT was adjusted for age, sex, glaucoma diagnosis, diabetes status, and prostaglandin analogs use for >12 months.

CONCLUSIONS

Optical low-coherence reflectometry is a widely used technology, which can measure CCT. Our study confirms that African Americans have the thinnest corneas followed by Asians. In the latter group, relatively thin CCT may partly explain their high rates of normal-tension 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.

Effect of timolol on central corneal thickness

PURPOSE

Timolol is an effective and safe medication that is widely used in glaucoma treatment. Although it is known that it is quickly taken up by the cornea following topical administration and that the cornea exhibits -adrenergic receptors, there are few studies available on the clinical impact of timolol on central corneal thickness (CCT).

METHODS

Twenty healthy subjects were tested in a double-blind, prospective, and randomized study. Intraocular pressure (IOP) and CCT were measured before and during administration of timolol 0.5% eyedrops over 28 days.

RESULTS

Administration of timolol 0.5% resulted in a reduction of IOP from an initial value of 16 ± 2 mm Hg to 13 ± 0 mm Hg (p&lt;0.001, R2 = 0.7033) as well as an increase in CCT from 555 ± 11 µm from the time of the baseline examination to 567 ± 9 µm (p = 0.005, R2 = 0.8754), an increase of epithelial thickness from 53 ± 2 µm to 59 ± 3 µm (p&lt;0.001, R2 = 0.5063), and an increase of stromal thickness from 494 ± 4 µm to 498 ± 9 µm (p = 0.045, R2 = 0.4352) after 9 days each. From day 10 on, a decrease in CCT (R2 = 0.6164), epithelial thickness (R2 = 0.2216), and stromal thickness (R2 = 0.2092) was observed. At the end, the values had returned toward the initial values measured (CCT 553 ± 8 µm, p = 0.391; epithelial thickness, 50 ± 2 µm, p = 0.214; and stromal thickness, 493 ± 8 µm, p = 0.483). In contrast, endothelial thickness did not vary following administration of timolol 0.5% (p = 0.727, R2 = 0.009).

CONCLUSIONS

Topical administration of timolol 0.5% results in a reversible increase in CCT. These modest changes are unlikely to influence tonometry or clinical decision-making.

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.

Effects of corneal thickness on the intraocular penetration of travoprost 0.004%

PURPOSE

To determine whether the intraocular penetration of travoprost 0.004% is affected by central corneal thickness.

METHODS

Sixty-four patients who were scheduled for cataract surgery without any other ophthalmologic pathology of significance were enrolled in this study. At 120 min before surgery, one drop of travoprost 0.004% was instilled in the eye to be operated on. At the start of surgery, a sample of aqueous humour was extracted to subsequently determine its AL-5848 concentration. These concentrations were compared among three groups of patients established according to central corneal thickness measurements obtained by ultrasound pachymetry.

RESULTS

Mean AL-5848 concentrations were 3.27±2.03 ng/ml in Group I (CCT<511 microns), 3.27±2.44 ng/ml in Group II (CCT≥511 and ≤574 microns), and 2.73±2.15 ng/ml in Group III (CCT>574 microns), indicating no significant differences among the groups.

CONCLUSIONS

We were unable to demonstrate the greater or lesser penetration of travoprost depending on corneal thickness, which could explain differences in patient responses to this drug.