Effect of Tafluprost 0.0015% on Central Corneal Thickness in Patients With Primary Open-angle Glaucoma

Comparison of Goldmann and ORA tonometers in newly diagnosed, untreated, POAG and OHT eyes

BACKGROUND AND OBJECTIVE

The corneal biomechanical properties in naïve, untreated glaucoma and ocular hypertension (OHT) eyes is interesting, because it may be a source of error in intraocular pressure (IOP) measurements by Goldmann applanation tonometer (GAT) and Ocular Response Analyzer (ORA) The main objective of this study was to evaluate the IOP values obtained using GAT and the ORA, in primary open angle glaucoma (POAG) and in OHT untreated eyes.

MATERIAL AND METHODS

Observational, masked, cross sectional observational study. Newly diagnosed, untreated POAG and OHT eyes were included.

RESULTS

51 POAG and 34 OHT eyes were analyzed. We found that IOPcc (IOP corneal-compensated) was significantly higher than GAT IOP in POAG (p = 0.0002) while we did not find any significant difference between both tonometers in OHT (p = 0.1).

CONCLUSIONS

GAT seems to underestimate the real IOP in untreated POAG eyes and it seems to be quite accurate in OHT eyes.

The Multifarious Effects of Various Glaucoma Pharmacotherapy on Corneal Endothelium: A Narrative Review

Corneal endothelium is a single cell layer that is mainly responsible for maintaining corneal clarity. Endothelial damage secondary to toxicity, stress, or genetic predisposition are common and in conjunction with the low regenerative ability of the cells, making their preservation critical for maintaining visual acuity. Patients with glaucoma, who are estimated to be close to 80 million worldwide, have a plethora of reasons for developing endothelial damage, being exposed to a spectrum that extends from various medical and surgical interventions to the disease itself. The wide spectrum of glaucoma pharmacotherapy that has been recently extended by addition of newer classes of medications has been the focus of extensive research on its effects on corneal endothelium. Both basic and clinical research have attempted to shine a light on the complex mechanisms associated with the effects of glaucoma medication on corneal endothelium and to answer the important question as to whether these findings are clinically significant. The aim of this review is to summarize and present current literature of the various findings, both from in vivo and in vitro studies that have focused on the complex relationship between different classes of glaucoma medication and their effect on corneal endothelium.

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.

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.

Latanoprost treatment differentially affects intraocular pressure readings obtained with three different tonometers

PURPOSE

To evaluate the apparent intraocular pressure (IOP) change observed after treatment with latanoprost in naive eyes of patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT) using Goldmann applanation tonometer (GAT), ocular response analyzer (ORA) and Corvis ST tonometry.

METHODS

Prospective observational cohort study. One eye from each of 59 newly diagnosed patients with POAG or OHT in our institution was analysed. IOP readings obtained using GAT, ORA and Corvis at baseline and after a 3-month period of treatment with latanoprost were compared. Additionally, pre- and post-treatment biomechanical corneal parameters provided by the Corvis tonometer were analysed.

RESULTS

There was no statistically significant difference between the apparent treatment-induced IOP reductions when GAT and ORA were compared (p > 0.05). In contrast, the treatment-induced IOP reduction recorded using the Corvis tonometer was significantly smaller compared to the apparent IOP reduction observed with GAT and ORA (p = 0.0001 for both comparisons). With respect to biomechanical corneal properties, statistically significant changes were found after 3 months of treatment with latanoprost for the first corneal applanation time (AT1) (p = 0.001), second corneal applanation time (AT2) (p = 0.001) and deformation amplitude (DA) (p = 0.0003).

CONCLUSION

Following a 3-month course of latanoprost, the apparent treatment-induced IOP reduction in previously naïve patients with POAG or OHT differed depending on the tonometer used. Certain corneal biomechanical parameters assessed using Corvis ST exhibited a significant change. The ocular hypotensive effect of prostaglandin analogues may be overestimated when chronically treated patients are measured using GAT or ORA.

Changes in spectral parameters of corneal pulse following canaloplasty

PURPOSE

To ascertain whether changes in the spectral content of the corneal pulse (CP) signal, measured in vivo in primary open-angle glaucoma (POAG) patients, indirectly reflect changes in corneal biomechanics after canaloplasty.

METHODS

Fifteen eyes of 15 POAG patients who underwent canaloplasty combined with phacoemulsification were enrolled. Standard ophthalmic examinations were conducted before washout, pre-operatively, at days 1, 7, and 1, 3, 6, and 12 months after surgery. Non-contact measurements of the CP signal were performed at pre-washout, pre-operatively, and at 3, 6, and 12 months post-operatively. Then, amplitudes of the CP first five harmonics associated with the heart rate were estimated. Temporal changes of all considered parameters were tested at a Bonferroni-adjusted significance level set to 0.005.

RESULTS

A decrease in the amplitude of the first harmonic and an increase in the normalized amplitude of the third harmonic (A_CP3n) of the CP signal were noticed between the pre-washout and the pre-operative stages (p = 0.003 and p = 0.004, respectively). This corresponds to an increase in median intraocular pressure (IOP) values by 6.0 mmHg (p = 0.0045). After surgery, A_CP3n reached the highest value at 3 months post-operatively, compared with pre-washout level (p = 0.0045).

CONCLUSIONS

Alterations in corneoscleral stiffness caused by surgery are reflected in changes in the A_CP3n value. Hence, post-operative corneal biomechanics could be monitored indirectly by this supporting indicator that can be used to estimate the time at which measures of IOP are no longer biased by the changed cornea boundary conditions caused by canaloplasty.

CLINICAL TRIALS REGISTRATION

NCT02908633.

Effect of Acute Increases in Intraocular Pressure on Corneal Pachymetry in Rabbit Eyes Treated with Timolol Maleate

Objective:

To evaluate in an in vivo rabbit model, the effect of topical timolol maleate therapy on the central corneal thickness response to acute intraocular pressure increases.

Method:

In this prospective and interventional controlled study, the central corneal thickness and intraocular pressure were measured in vivo in 12 rabbit eyes treated with topical timolol maleate for 1 month and in 12 controls at baseline, and after the intraocular pressure (measured by direct cannulation of the anterior chamber) was increased to 15 and 30 mmHg using a forced saline infusion into the anterior chamber.

Results:

There were no significant differences in the basal central corneal thickness values (control group, 373.2±12.9 µm; study group, 377.5±19.2 µm, p=0.5) or the central corneal thickness values when the intraocular pressure was increased to 15 mmHg (control group, 335.2±14.3 µm; study group, 330.0±32.1 µm, p=0.6) and to 30 mmHg (study group, 318.8±25.3 µm; control group, 329.8±21.0 µm, p=0.3).

Conclusion:

Rabbit corneas treated with topical timolol maleate for 1 month did not show a strain response to acute intraocular pressure increases that differed from control eyes. This is in contrast to a previous finding in which rabbit eyes treated with prostaglandin analogues had a greater decrease in central corneal thickness in response to a sudden intraocular pressure increase compared with untreated corneas.

Effect of a Topical Combination of Latanoprost and Pranoprofen on Intraocular Pressure and the Ocular Surface in Open-Angle Glaucoma Patients

Objective

A prospective study was performed to observe the effects of nonsteroidal anti-inflammatory drug (NSAID) eyedrops on intraocular pressure (IOP) and the ocular surface in primary open-angle glaucoma (POAG) patients treated with 0.005% latanoprost eyedrops.

Methods

Forty-eight subjects were randomized into two study groups (NSAID and control). Latanoprost was continued for 10 weeks in all subjects. At the end of week 4, pranoprofen was added in the NSAID group, and treatment lasted for 4 weeks, whereas patients in the control group were treated with latanoprost alone. IOP was measured in both groups every 2 weeks, and the changes in the ocular surface in the NSAID group were evaluated once a month.

Results

Pranoprofen addition resulted in a decrease in IOP in the NSAID group compared to the control group (p < 0.01). After pranoprofen was discontinued, IOP significantly increased in the NSAID group (p < 0.01), remaining approximately at the same IOP as when they were being treated with latanoprost alone. During the same examination, no significant variations in IOP were found in the control group. Patients who were treated with latanoprost alone showed gradual improvements in ocular surface symptom scores and conjunctival hyperemia scores during the first four weeks of treatment (p < 0.01). When pranoprofen eyedrops were added, ocular surface symptom scores decreased (p < 0.01), but conjunctival hyperemia scores did not change significantly.

Conclusions

For POAG patients treated with latanoprost, the combination of pranoprofen can not only significantly enhance the latanoprost-induced IOP-lowering effect but also relieve the uncomfortable ocular symptoms caused by latanoprost.

The thick and thin of the central corneal thickness in glaucoma

Central corneal thickness (CCT) is an important parameter in the assessment of any potential glaucoma patient. While it affects prognosis in ocular hypertension, its value in patients diagnosed with glaucoma is less certain. There are several biological factors and genetic components that may influence glaucoma progression, which have been associated with thinner CCT. The CCT itself can be affected by several factors including ethnicity, age, sex, glaucoma medications, genetics, and the subtype of glaucoma. Besides, there is variability in the measurement of CCT between difference types of devices. These factors need to be considered in the evaluation of glaucoma patients' CCT and its effect on interpretation of intraocular pressure levels and risk stratification.

Central corneal thickness in glaucoma

PURPOSE OF REVIEW

The purpose of this review is to summarize the role of central corneal thickness (CCT) in the clinical management of a glaucoma patient.

RECENT FINDINGS

The prognostic value of CCT is well recognized in patients with ocular hypertension. However, its predictive value in other glaucoma suspects and patients with established glaucoma is less certain. Tonometry artefacts can result from variations in CCT. However, an adequately validated correction algorithm for Goldmann applanation tonometry measurements does not exist. Newer methods of tonometry are potentially less influenced by CCT but are limited in their clinical use. There may also be biological and genetic associations between corneal thickness and glaucoma. Demographics, environmental factors, glaucoma treatment and the measurement device used have a significant influence on CCT, and should be considered when interpreting the effect of cornea thickness in patients with glaucoma. New measurements of the biomechanical properties of the cornea are likely to be better approximations of the globe biomechanics than CCT, but these require further evaluation.

SUMMARY

The clinical significance of CCT is well recognized in the context of glaucoma diagnosis and management, though the extent of its importance remains debatable. Corneal biomechanical properties may be more significantly associated with glaucoma than CCT.

Effect of topical prostaglandin analogues on corneal hysteresis

PURPOSE

To evaluate possible changes in corneal hysteresis (CH) after topical treatment with a prostaglandin analogue in medication-naïve eyes.

METHODS

This was a prospective, observational cohort study. Sixty-eight eyes of 68 patients were prospectively included who were newly diagnosed with primary open-angle glaucoma or ocular hypertension in our institution. All patients were treatment-naïve. Patients were evaluated at baseline and after 6 months of treatment with latanoprost in the eye with the lower intraocular pressure (IOP) measured by Goldmann applanation tonometry (GAT). The ocular response analyzer was used to measure CH.

RESULTS

CH increased significantly (p = 0.0001) from 8.96 ± 2.3 mmHg to 9.79 ± 1.97 mmHg, and this increase was correlated significantly (p = 0.0001, r = 0.64, r(2) = 0.41) with the basal CH. We identified a weak but significant (r(2) = 0.06, p = 0.01) relationship between the basal CH and the drug-induced reduction of the GAT IOP. Nevertheless, the increase in the drug-induced CH was not correlated with the decrease in the GAT IOP.

CONCLUSION

Treatment with latanoprost increases CH. The CH increase was not correlated with the drug-induced decrease in the GAT IOP, which suggested a direct effect of latanoprost on the viscoelastic corneal properties.