Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide [ISRCTN18873428]

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.

NCX 470 Restores Ocular Hemodynamics and Retinal Cell Physiology After ET-1-Induced Ischemia/Reperfusion Injury of Optic Nerve and Retina in Rabbits

Purpose: Determine whether NCX 470, a nitric oxide (NO)-donating bimatoprost with clinically demonstrated intraocular pressure (IOP)-lowering effects, improves ocular hemodynamics and retinal physiology. Methods: Endothelin-1 (ET-1)-induced ischemia/reperfusion model in New Zealand white rabbits was used. ET-1 was injected next to the optic nerve twice/week (Monday and Thursday) for 6 weeks. Starting on week 3, animals received NCX 470 (0.1% bid, 6 days/week Monday-Saturday) or vehicle until the end of ET-1 treatment. IOP, ophthalmic artery resistive index (OA-RI) and retina physiology (electroretinogram, ERG) were determined before dosing and at different times post-dosing. All measurements were taken on Mondays before the AM daily dosing (36 h treatment-free). Finally, oxidative stress markers were determined in dissected retina and iris/ciliary body of treated eyes. Results: Injection of ET-1 progressively increased IOP (20.7 ± 0.6, 24.9 ± 1.2, and 27.0 ± 0.6 mmHg at baseline, week 2 and 6, respectively) and OA-RI (0.30 ± 0.02, 0.39 ± 0.02, and 0.42 ± 0.03 at baseline, week 2 and 6, respectively) and reduced rods and/or cones response as indicated by changes in ERG amplitudes under different stimulating conditions. NCX 470 re-established baseline IOP (21.8 ± 1.0 mmHg), OA-RI (0.33 ± 0.02), and ERG amplitude by week 6 (mostly rod response, ^0.01Dark_A_{Veh_6week} = 32.2 ± 3.0 μV and ^0.01Dark_A_{NCX470_6week} 44.3 ± 4.5 μV; mostly cone response, ^3.0Dark_A_{Veh_6week} = 87.6 ± 10.1 μV and ^3.0Dark_A_{NCX470_6week} = 122.8 ± 11.4 μV; combined rod/cone response, ^3.0Light_A_{Veh_6week} = 49.8 ± 6.5 μV and ^3.0Light_A_{NCX470_6week} = 64.2 ± 6.8 μV). NCX 470 also reversed ET-1-induced changes in glutathione and manganese superoxide dismutase (oxidative stress markers) in retina and iris/ciliary body. Conclusions: Repeated ocular topical dosing with NCX 470 reverses ET-1-induced changes in IOP, OA-RI, and ERG suggesting improved ocular hemodynamics and retinal physiology likely independently from its demonstrated IOP-lowering effect.

Dorzolamide/Timolol Fixed Combination: Learning from the Past and Looking Toward the Future

The key clinical attributes of preserved dorzolamide/timolol fixed combination (DTFC) and the emerging potential of preservative-free (PF) DTFC are reviewed with published evidence and clinical experience. The indications and role of DTFC in current glaucoma management are critically discussed. Preserved DTFC became the first intraocular pressure (IOP)-lowering fixed combination (FC) approved by the US Food and Drug Administration (FDA) and remains one of most commonly used medications worldwide. The pharmacological properties of DTFC reflect those of its two time-tested constituents, i.e., the carbonic anhydrase inhibitor dorzolamide and the non-selective beta-blocker timolol. In regulatory studies DTFC lowers IOP on average by 9 mmHg (32.7%) at peak and by 7.7 mmHg (27%) at trough. In trials DTFC shows equivalence to unfixed concomitant therapy, but in real-life practice it may prove superior owing to enhanced convenience, elimination of the washout effect from the second drop, improved tolerability, and better adherence. PF DTFC became the first PF FC approved, first in unit-dose pipettes, and more recently in a multidose format. Cumulative evidence has confirmed that PF DTFC is at least equivalent in efficacy to preserved DTFC and provides a tangible clinical benefit to patients with glaucoma suffering from ocular surface disease by improving tolerability and adherence. Finally, we identify areas that warrant further investigation with preserved and PF DTFC

Effects of the Glaucoma Drugs Latanoprost and Brimonidine on Corneal Temperature

Purpose

The aim of this study was to investigate the effects of the glaucoma drugs latanoprost, brimonidine, and the combination of both on the central corneal temperature (CT) of healthy subjects by means of infrared thermography. Changes of the central CT may reflect changes of ocular blood flow.

Methods

Before application and during 2 hours after the application of latanoprost, brimonidine, or the combination of both in one eye, the CT in both eyes of 40 healthy subjects was measured repeatedly.

Results

Brimonidine reduced CT by approximately 0.5°C. This effect was statistically significant (P < 0.0001). Latanoprost, however, had a very small and insignificant influence (P = 0.47). Accordingly, the combination of brimonidine and latanoprost also reduced CT up to 0.5°C, and this effect was statistically significant (P < 0.0001).

Conclusions

Brimonidine, but not latanoprost, had a significant effect on central CT. This cooling effect of brimonidine is most probably due to a drug-induced reduction of blood circulation in the ciliary body and iris and to a certain extent also to a reduction of blood flow in the fundus of the eye.

Translational Relevance

This study shows evidence that thermography of the cornea provides indirect information on the influence of drugs on the blood flow to the anterior segment of the patient's eye.

Comparison of flow velocity in ophthalmic artery between glaucomatous and normal subjects

Purpose: To study the hemodynamic parameters in ophthalmic artery (OA) using color Doppler imaging in subjects with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG) and age matched normals. Methods: Sixty-eight eyes of 68 subjects (41 males and 27 females) constituted material for this prospective observational study. They were divided into three groups; Group A had 24 patients with POAG, Group B had 18 patients with NTG and Group C had 26 normal subjects. They underwent CDI of OA. The outcome variables were peak systolic velocity (PSV), end diastolic velocity (EDV), resistivity index (RI) and pulsatility index (PI). Data were compiled and analyzed using one-way ANOVA analysis. Results: The mean ± SD age of POAG patients, NTG patient and normal subjects was 59.95 ± 7.35, 58.11 ± 9.97 and 57.73 ± 5.39 years, respectively. The mean intra ocular pressure (IOP) was 29.8 ± 5.0, 15.9 ± 2.4 and 16.6 ± 1.7mm Hg in Group A, B and C, respectively. In group A, the mean PSV, EDV, RI and PI were 18.2 ± 3.80, 3.71 ± 1.40, 0.93 ± 0.12 and 2.8 ± 0.42. In group B, 26.6 ± 1.72, 4.93 ± 1.32, 0.84 ± 0.02 and 1.32 ± 0.20 and in group C, 35.4 ± 3.04, 8.08 ± 0.69, 0.77 ± 0.03 and 1.80 ± 0.17, respectively. All the values were found to be statistically significant (p < 0.05). Lower PSV and EDV were found in POAG and NTG patients, while RI was higher than in normal subjects. Conclusion: The hemodynamic parameters are significantly affected in POAG and NTG patients. The PSV and EDV are decreased and RI is increased. EDV is more sensitive for the assessment of hemodynamic changes.

Accuracy of peripapillary versus macular vessel density in diagnosis of early to advanced primary open angle glaucoma

PURPOSE

To evaluate macular and peripapillary vessel density (mVD, pVD) using optical coherence tomography angiography (OCT-A) in healthy subjects, patients with ocular hypertension (OHT) and primary open-angle glaucoma (POAG) patients.

METHODS

In this prospective observational study, OCT-A images were obtained from 60 eyes of 36 healthy, ocular hypertension (OHT), preperimetric glaucoma (PPG), early glaucoma (EG) and moderate and advanced POAG subjects. Superficial mVD was acquired over a 6×6-mm cube centered on the foveal avascular zone and pVD over a 4.5×4.5-mm cube centered on the optic disc. Peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell complex (GCC) thickness was calculated using spectral-domain OCT. Correlations between vascular, structural and Humphrey VF indices were evaluated (Spearman's rank correlation coefficient).

RESULTS

Median pVD and mVD in the PPG eyes were lower than in healthy eyes (51.87% and 47.23% versus 55.70% and 53.61%, respectively; P<0.001 and P=0.003), but higher than in mild glaucoma eyes (46.21% and 41.98%, P<0.001 compared to normal eyes) and moderate to advanced glaucoma eyes (37.45% and 39.89%, P<0.0001 compared to normal eyes). The highest correlations were found between structural parameters and pVD (r=0.87 and 0.86 for pRNFL and GCC, P<0.0001), followed by mVD (r=0.69 for both pRNFL and GCC, P<0.0001). Correlations with mean VF sensitivity were similar for pVD and mVD (r=0.61 and 0.56) and for GCC and pRNFL (r=0.60 and 0.52, P<0.0001 for all).

CONCLUSIONS

VD measured with OCT-A shows reduction in POAG. Detection of this damage differentiates PPG from normal and perimetric POAG eyes with a high correlation with structural parameters. Peripapillary VD accuracy is higher than mVD in detecting the disease. These results suggest that OCT-A could improve POAG diagnosis and understanding of the pathophysiologic mechanisms behind glaucoma.

Effect of Latanoprost on Choroidal Thickness

PURPOSE

The purpose of this study was to evaluate the changes in choroidal thickness during the use of latanoprost eyedrops which shift fluid to the suprachoroidal space and change choroidal perfusion.

MATERIALS AND METHODS

This prospective study included 34 eyes of 17 bilateral glaucoma or ocular hypertensive patients who had no previous hypotensive therapy. Each patient had both eyes treated with latanoprost. Each patient also underwent a complete ophthalmological examination and optical coherence tomography measurement. Choroidal thickness measurements by optical coherence tomography were carried out on the first visit before latanoprost use and at time intervals of 7 and 30 days of therapy.

RESULTS

The patients' mean age was 62.3±11 years (range, 30 to 83 y). Of 17 patients, 7 were female individuals. There were no significant differences in central choroidal thicknesses at the fovea, or at each point within the horizontal nasal and temporal quadrants between visits (P<0.05 for all comparisons).

CONCLUSIONS

The current study showed that choroidal thickness does not change after latanoprost therapy. However, the choroidal changes of anterior part of the eye can be effected by the latanoprost therapy. Future studies investigating the anterior part of the eye and focusing on both choroidal perfusion and choroidal thickness may give additional information concerning the mechanism of action.

Effects of Dorzolamide on Retinal and Choroidal Blood Flow in the DBA/2J Mouse Model of Glaucoma

PURPOSE

To test the hypothesis that acute topical dorzolamide (DZ) decreases intraocular pressure (IOP) and increases retinal and choroidal blood flow in the DBA/2J mouse model of glaucoma.

METHODS

Retinal and choroidal blood flow were measured in 4- and 9-month-old DBA/2J mice, and 4-month C57BL/6 (control) mice under isoflurane anesthesia using magnetic resonance imaging. Ocular blood flow was measured at baseline, and 1 and 2 hours after topical dorzolamide. Intraocular pressure was measured using a rebound tonometer in a subset of animals at the same time points.

RESULTS

Baseline IOP in the 4-month-old DBA/2J mice and C57BL/6 mice was not significantly different (P > 0.05), and IOP in both groups was less than in the 9-month-old DBA/2J mice (P < 0.05 for both). Compared to baseline, dorzolamide reduced IOP at 1 and 2 hours after dorzolamide in the 4- (P < 0.05) and 9-month-old (P < 0.01) DBA/2J mice, but not in the C57BL/6J mice (P > 0.05). Baseline retinal blood flow was lower in the 4-month and 9-month-old DBA/2J mice compared with the 4-month-old C57BL/6J mice (P < 0.05). Baseline choroidal blood flow in the 9-month-old DBA/2J mice was less than in the C57BL/6J mice (P < 0.05). Compared with baseline, both retinal and choroidal blood flow increased at 1-hour post-dorzolamide and remained elevated 2 hours later in the 9-month-old DBA/2J mice (P < 0.05).

CONCLUSIONS

Dorzolamide lowers IOP and raises retinal and choroidal blood flow in older DBA/2J mice, consistent with the study hypothesis.

Effects of dorzolamide/timolol fixed combination on retrobulbar hemodynamics in pseudoexfoliative glaucoma

In our study we aimed to evaluate the short-term effects of dorzolamide/timolol on ocular perfusion pressure and retrobulbar blood flow in patients with pseudoexfoliative glaucoma (PXG). This prospective observational cross-sectional study enrolled 22 eyes of 22 newly-diagnosed patients with PXG in a single center. All of the patients received a fixed combination of dorzolamide/timolol. Besides routine ophthalmologic examination, the retrobulbar hemodynamic parameters in the ophthalmic artery, central retinal artery, and short posterior ciliary arteries were measured in all participants at baseline and the 3(rd) month using color Doppler imaging. The mean intraocular pressure (IOP) was 22.3 ± 2.1 mmHg at baseline and reduced to 17.4 ± 2.3 mmHg at the 3(rd) month (p < 0.05). None of the retrobulbar parameters, except peak systolic velocity and resistive index in temporal short posterior ciliary arteries, changed significantly on therapy with dorzolamide/timolol fixed combination when the results were analyzed at Month 3. The drug significantly decreased the peak systolic velocity (p = 0.044) and reduced the resistive index in 0.04 units, 95% confidence interval 0.03-0.05, (p < 0.001) in the temporal short posterior ciliary arteries. This study reports that the retrobulbar hemodynamics might be affected less than expected by dorzolamide/timolol fixed combination in patients with PXG although the reduction of IOP was statistically significant.

Influence of latanoprost on retinal microcirculation in glaucoma

Purpose :

To test whether latanoprost has an influence on ocular haemodynamics, considering the general reputation of prostaglandins which is frequently associated with vasoconstriction. The effect of latanoprost on the retinal blood supply of treatment-naïve glaucoma patients was tested.

Materials and Methodology :

13 patients (7 male, 6 female) who had just recently been diagnosed with primary open-angle glaucoma (POAG) were treated with latanoprost (0.005%). The average age of our study group was 63.8 years (+/- 2.9 years).

The drug’s effect on retinal autoregulation was assessed by flicker test using the Dynamic Vessel Analyzer (DVA). Examinations took place before initializing treatment, after 4 weeks and once again after 4 to 6 months.

Results :

In our group of POAG patients, the IOP under treatment was significantly reduced about 25%. No intraindividual differences in systemic blood pressure and heart rate were observed. In DVA measurements of glaucoma patients, the maximum flicker dilation of the arteries was significantly lower than reported for healthy volunteers. Beyond that, POAG patients did not show significant differences in vessel diameters, peak amplitudes as well as maximum dilations of retinal arteries and veins before and under treatment with latanoprost (0.005%).

Conclusion :

Latanoprost markedly lowered the IOP but it did not exert a significant effect on retinal haemodynamics. There was neither a tendency towards vasoconstriction nor towards vasodilation. Sustaining reperfusion damage after topical latanoprost therapy thus seems to be highly unlikely. Further studies must show if sole IOP lowering or a dual positive effect – IOP lowering and improvement of retinal vessel autoregulation – have a more positive impact on the long term follow-up of glaucoma patients.

Effects of treatment with bimatoprost 0.03% for 3 years in patients with normal-tension glaucoma

Purpose

To evaluate the effects of bimatoprost 0.03% single treatment for 3 years on intraocular pressure (IOP) and visual field performance.

Methods

We monitored the IOP of 62 patients with normal-tension glaucoma every 1–3 months. The Humphrey visual field test was performed every 6 months after treatment and the results obtained were compared to those before treatment. In addition, visual field performance was evaluated using trend and event analysis.

Results

The mean ± standard deviation (SD) of IOP after treatment with bimatoprost for 3 years (13.6±3.1 mmHg) was significantly lower than that before treatment (16.8±2.4 mmHg, P<0.0001). No change was observed in the mean deviation and pattern SD values of the Humphrey visual field before and 3 years after treatment. Worsening of visual field performance was observed in one patient (3.0%) by using trend analysis and in four patients (12.1%) by using event analysis. Treatment was discontinued in 17 patients (27.4%) because of adverse reactions.

Conclusion

Bimatoprost 0.03% single treatment was effective in reducing the IOP at least during the 3 years of treatment, but visual field performance worsened by 3.0%–12.1% in patients with normal-tension glaucoma.

Effects of antiglaucoma drugs on blood flow of optic nerve heads and related structures

An association between glaucoma development or progression and compromised ocular blood flow has been postulated as a result of population-based studies and prospective cohort studies. Blood flow in the optic nerve head (ONH) is of primary importance in the pathogenesis of glaucoma. The potential to modify the blood flow in the ONH and its related structures has been reported in various agents, including topical antiglaucoma drugs and systemic drugs such as calcium channel antagonists, which are reviewed in this manuscript. Clinical implications of the improvement in ocular blood flow on the treatment of glaucomatous optic neuropathy require further investigation.

Topical treatment for 1 week with latanoprost but not diclofenac reduces the diameter of dilated retinal arterioles in patients with type 1 diabetes mellitus and mild retinopathy

PURPOSE

Diabetic retinopathy is characterised by morphological lesions secondary to retinal vascular impairment, and it is assumed that changes in the diameter regulation of retinal arterioles are involved in the disease pathogenesis. It has previously been shown that prostaglandin F2α can constrict retinal arterioles in vitro. In the present study, we investigated whether a similar effect could be achieved by topical administration in diabetic patients with dilated retinal arterioles and retinopathy.

METHODS

Twenty-two type 1 diabetic patients with mild retinopathy and twenty-four matched normal controls were randomized to topical treatment with the prostaglandin F2α agonist latanoprost twice daily for 1 week, followed by similar treatment with the cyclo-oxygenase inhibitor diclofenac, or to receive the two medications in the reverse order. The Dynamic Vessel Analyzer was used to assess the effect of the interventions on the resting diameter of retinal vessels and on the diameter response of retinal arterioles to increased blood pressure (BP) induced by isometric exercise and flicker stimulation.

RESULTS

Latanoprost reduced the resting diameter of retinal arterioles significantly in patients with diabetes (p = 0.01), but had no effect on normal persons. Diclofenac had no effect on the resting diameter of arterioles in either of the groups. The diameter responses to increased BP and flicker stimulation were not significantly changed by any of the treatments.

CONCLUSION

Long-term prospective studies are needed to study the effect of topical treatment with latanoprost on the consequences of retinal hyperperfusion in retinal vascular diseases such as diabetic retinopathy.

Observations on degenerative changes within the optic nerve in patients with primary open glaucoma and arterial hypertension: 6-month follow-up

The authors aimed to determine the effect of the time of hypotensive drug administration on the progress of degenerative changes within the optic nerve in patients with hypertension and glaucoma. Two groups were included in the study: group A comprised patients-dippers taking drugs in the mornings, and group B comprised patients-nondippers taking drugs both in the mornings and in the evenings. After 6 months, group B showed significant drops in nocturnal diastolic blood pressure (BP) (month 1=73.27 mm Hg vs month 6=67.50 mm Hg), nocturnal mean BP (89.34 vs 84.65 mm Hg), and minimum diastolic BP (50.74 vs 44.03 mm Hg). Group B also showed significant reductions in nocturnal ocular perfusion pressure (43.0 vs 39.73), retinal nerve fiber layer thickness (131.31 vs 113.12 μm), and flow in the eye vessels. Taking hypotensive drugs in the evening may significantly decrease blood flow in the eye arteries, cause degenerative changes within the optic nerves, and result in greater loss in the field of vision.

Dorzolamide-induced relaxation of intraocular porcine ciliary arteries in vitro depends on nitric oxide and the vascular endothelium

PURPOSE

Carbonic anhydrase inhibitors (CAIs) are used to reduce aqueous production in glaucoma, which includes a direct effect on the ciliary body. However, CAIs also affect ciliary blood flow, but the mechanisms of action of CAIs on the tone of intraocular ciliary arteries supplying the ciliary body have not been studied in detail.

MATERIALS AND METHODS

The intraocular part of porcine ciliary arteries was isolated and mounted in a wire myograph system for isometric tension recordings. After contraction with the thromboxane analogue U46619, the vasorelaxing effect of the CAIs acetazolamide, brinzolamide and dorzolamide was studied. Subsequently, the involvement of the carbonic anhydrase reaction and nitric oxide (NO) in dorzolamide-induced vasorelaxation was characterized.

RESULTS

All CAIs induced relaxation of contracted ciliary arteries, but the effect of dorzolamide was most pronounced. Dorzolamide-induced relaxation was unaffected by changes in pH and CO(2), and by removal of substrates to the carbonic anhydrase enzyme, but was abolished after inhibition of NO synthase and guanylyl cyclase and after removal of the vascular endothelium.

CONCLUSIONS

Dorzolamide-induced vasorelaxation of ciliary arteries is independent of changes in the substances involved in the carbonic anhydrase reaction, but depends on NO and the vascular endothelium. The mechanism of action of dorzolamide in ocular disease may involve an effect on vascular tone mediated by NO.

Use of colour Doppler imaging in ocular blood flow research

The main objective of this report is to encourage consistent quality of testing and reporting within and between centres that use colour Doppler imaging (CDI) for assessment of retrobulbar blood flow. The intention of this review is to standardize methods in CDI assessment that are used widely, but not to exclude other approaches or additional tests that individual laboratories may choose or continue to use.

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: a review of its use in open-angle glaucoma and ocular hypertension

Bimatoprost (Lumigan) is a synthetic prostamide that reduces intraocular pressure (IOP) by increasing the outflow of aqueous humour. In patients with open-angle glaucoma or ocular hypertension, long-term treatment (for up to 48 months) with once-daily bimatoprost 0.03% ophthalmic solution was more effective than timolol twice daily in providing a sustained and stable reduction in IOP. Bimatoprost 0.03% ophthalmic solution demonstrated efficacy similar to, or greater than, the prostaglandin analogues latanoprost and travoprost in reducing IOP and achieving target IOP levels. Switching to bimatoprost was as effective in maintaining diurnal IOP control as switching to a fixed combination of latanoprost/timolol (in patients with IOP levels controlled with a nonfixed combination of latanoprost plus timolol), and similarly, or more, effective in lowering IOP and providing overall diurnal IOP control than switching to a combination of dorzolamide/timolol (in patients with IOP inadequately controlled with other antiglaucoma agents including timolol). Treatment with bimatoprost was generally well tolerated, with conjunctival hyperaemia (mostly mild), growth of eyelashes and ocular pruritus being commonly reported. Other adverse events included increases in the pigmentation of the iris, perorbital areas and eyelashes.

Mirtogenol potentiates latanoprost in lowering intraocular pressure and improves ocular blood flow in asymptomatic subjects

Purpose:

The dietary supplement Mirtogenol^® was previously shown to lower elevated intraocular pressure (IOP). We here present the effects of this supplement on IOP in comparison as well as in combination with latanoprost eye drops.

Methods:

Seventy-nine patients with asymptomatic ocular hypertension were randomly assigned to three groups receiving either the supplement, or latanoprost eye drops, or both in combination. Intraocular pressure and retinal blood flow were investigated in monthly intervals over 24 weeks.

Results:

Mirtogenol alone lowered IOP from baseline 38.1 to 29.0 mmHg after 16 weeks, with little further improvement during the following eight weeks. Latanoprost rapidly lowered IOP from baseline 37.7 to 27.2 mmHg within four weeks, without further effects thereafter. The combination of the supplement and latanoprost lowered IOP from 38.0 to 27.3 mmHg after four weeks, and further decreased IOP to 24.2 mmHg after six weeks. After 24 weeks IOP with the combination treatment (23.0 mmHg) was significantly lower than with latanoprost alone (27.2 mmHg). Mirtogenol and latanoprost individually showed comparable effects for gradually increasing central artery blood flow with treatment duration. Combination treatment showed higher systolic blood flow velocity throughout the trial period. The diastolic blood flow velocity gradually increased with treatment duration in all three groups. From twelve weeks onwards, the diastolic component with combination treatment was higher than with individual treatments.

Conclusions:

Mirtogenol lowered elevated IOP in patients almost as effectively as latanoprost, however, it takes much longer (24 vs 4 weeks). The combination of both was more effective for lowering IOP and the combination yielded better retinal blood flow. No serious side effects occurred during the study, apart from standard side effects in patients related to Latanoprost. These promising results warrant further research of Mirtogenol with a larger patient group.

Meta-analysis of medical intervention for normal tension glaucoma

OBJECTIVE

To evaluate the intraocular pressure (IOP) reduction achieved by the most frequently prescribed antiglaucoma drugs in patients with normal tension glaucoma (NTG).

DESIGN

Systematic review and meta-analysis.

PARTICIPANTS

Fifteen randomized clinical trials reported 25 arms for peak IOP reduction, 16 arms for trough IOP reduction, and 13 arms for diurnal curve IOP reduction.

METHODS

Pertinent publications were identified through systematic searches of PubMed, EMBASE, and the Cochrane Controlled Trials Register. The patients had to be diagnosed as having NTG. Methodological quality was assessed by the Delphi list on a scale from 0 to 18. The pooled 1-month IOP-lowering effects were calculated using the 2-step DerSimonian and Laird estimate method of the random effects model.

MAIN OUTCOME MEASURES

Absolute and relative reductions in IOP from baseline for peak and trough moments.

RESULTS

Quality scores of included studies were generally high, with a mean quality score of 12.7 (range, 9-16). Relative IOP reductions were peak, 15% (12%-18%), and trough, 18% (8%-27%) for timolol; peak, 14% (8%-19%), and trough, 12% (-7% to 31%) for dorzolamide; peak, 24% (17%-31%), and trough, 11% (7%-14%) for brimonidine; peak, 20% (17%-24%), and trough, 20% (18%-23%) for latanoprost; peak, 21% (16%-25%), and trough, 18% (14%-22%) for bimatoprost. The differences in absolute IOP reductions between prostaglandin analogues and timolol varied from 0.9 to 1.0 mmHg at peak and -0.1 to 0.2 mmHg at trough.

CONCLUSIONS

Latanoprost, bimatoprost, and timolol are the most effective IOP-lowering agents in patients with NTG.

Bimatoprost/timolol: a review of its use in glaucoma and ocular hypertension

Topically administered bimatoprost 0.03%/timolol 0.5% ophthalmic solution (bimatoprost/timolol: Ganfort) comprises the synthetic prostamide bimatoprost (structurally related to prostaglandin F2 alpha) and the beta-adrenergic receptor antagonist timolol. Bimatoprost/timolol (one drop administered in the affected eye[s] once daily in the morning or evening) is an effective and well tolerated fixed combination for lowering intra-ocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension (OHT), including individuals uncontrolled on monotherapy with a beta-adrenergic receptor antagonist or prostaglandin analogue/prostamide.

Effects of dorzolamide on choroidal blood flow, ciliary blood flow, and aqueous production in rabbits

PURPOSE

To determine the effects of topical dorzolamide (a carbonic anhydrase inhibitor) on choroidal and ciliary blood flow and the relationship between ciliary blood flow and aqueous flow.

METHODS

The experiments were performed in four groups of pentobarbital-anesthetized rabbits treated with topical dorzolamide (2%, 50 microL). In all groups, intraocular pressure (IOP) and mean arterial pressure (MAP) at the eye level were measured continuously by direct cannulation. In group 1, aqueous flow was measured by fluorophotometry before and after dorzolamide treatment. In group 2, aqueous flow was measured after dorzolamide at normal MAP and while MAP was held constant at 80, 55, or 40 mm Hg with occluders on the aorta and vena cava. In group 3, the same MAP levels were used, and ciliary blood flow was measured transsclerally by laser Doppler flowmetry (LDF). In group 4, choroidal blood flow was measured by LDF with the probe tip positioned in the vitreous over the posterior pole during ramp increases and decreases in MAP before and after dorzolamide.

RESULTS

Dorzolamide lowered IOP by 19% (P < 0.01) and aqueous flow by 17% (P < 0.01), and increased ciliary blood flow by 18% (P < 0.01), which was associated with a significant reduction in ciliary vasculature resistance (-7%, P < 0.01). Dorzolamide shifted the relationship between ciliary blood flow and aqueous flow downward relative to the previously determined control relationship in the rabbit. Dorzolamide did not alter choroidal blood flow, choroidal vascular resistance, or the choroidal pressure flow relationship.

CONCLUSIONS

Acute topical dorzolamide is a ciliary vasodilator and has a direct inhibitory effect on aqueous production, but it does not have a detectable effect on choroidal hemodynamics at the posterior pole in the rabbit.

Discrepancy between results and abstract conclusions in industry- vs nonindustry-funded studies comparing topical prostaglandins

PURPOSE

To investigate the relationship between industry- vs nonindustry-funded publications comparing the efficacy of topical prostaglandin analogs by evaluating the correspondence between the statistical significance of the publication's main outcome measure and its abstract conclusions.

DESIGN

Retrospective, observational cohort study.

METHODS

English publications comparing the ocular hypotensive efficacy between any or all of latanoprost, travoprost, and bimatoprost were searched from the MEDLINE database. Each article was reviewed by three independent observers and was evaluated for source of funding, study quality, statistically significant main outcome measure, correspondence between results of main outcome measure and abstract conclusion, number of intraocular pressure outcomes compared, and journal impact factor. Funding was determined by published disclosure or, in cases of no documented disclosure, the corresponding author was contacted directly to confirm industry funding. Discrepancies were resolved by consensus. The main outcome measure was correspondence between abstract conclusion and reported statistical significance of the publications' main outcome measure.

RESULTS

Thirty-nine publications were included, of which 29 were industry funded and 10 were nonindustry funded. The published abstract conclusion was not consistent with the results of the main outcome measure in 18 (62%) of 29 of the industry-funded studies compared with zero (0%) of 10 of the nonindustry-funded studies (P = .0006). Twenty-six (90%) of the industry-funded studies had proindustry abstract conclusions.

CONCLUSIONS

Twenty-four percent of the industry-funded publications had a statistically significant main outcome measure; however, 90% of the industry-funded studies had proindustry abstract conclusions. Both readers and reviewers should scrutinize publications carefully to ensure that data support the authors' conclusions.

Latanoprost ophthalmic solution in the treatment of open angle glaucoma or raised intraocular pressure: a review

Latanoprost is a prostaglandin F2-alpha isopropyl ester prodrug which is rapidly hydrolyzed by esterases in the cornea to the biologically active latanoprost acid. When latanoprost is topically administered into the eye, the cornea seems to act like as a slow-release depot to the anterior segment. One hour after administration maximum concentration is found in the iris, followed by the anterior chamber and the ciliary body. Despite extensive research, controversy remains about the real mechanism of action of this drug. Immunohistochemical data have shown that the intraocular pressure (IOP) reduction with topical prostaglandin F2-alpha is associated with a reduction of collagens within the uveoscleral outflow pathway. Evidence from several experimental and clinical studies suggests that latanoprost is a valuable addition first-line treatment alternatives for glaucoma, ocular hypertension and even angle-closure glaucoma. Strong points are its efficacy, which is demonstrated to be higher than that of brimonidine, dorzolamide and timolol with fewer systemic adverse effects; a convenient administration schedule; and the IOP-controlling pattern, which is relatively flat compared with timolol and dorzolamide, and enables better control in glaucoma progression, since large fluctuations may be associated with the risk of developing glaucoma in untreated ocular hypertensive subjects.

Recurrent serous macular detachment after topical ocular hypotensive medication

We document the recurrence of a CSMD in a patient subsequent to the instillation of topical ocular hypotensive medications and its resolution on discontinuation of therapy. An independent cause or causes contributing to the development of CSMD other than the use of topical ocular hypotensive medications cannot be ruled out in this case, neither can it be considered dissociated from the use of these drugs. We recommend that patients with VTS, those with a history of CSMD or having developed recurrent episodes of CSMD requiring management with topical ocular hypotensive medications, be cautiously monitored for the possible occurrence or exacerbation of CSMD.

Comparison of the effects of travoprost, latanoprost and bimatoprost on ocular circulation: a 6-month clinical trial

PURPOSE

To study the effect of three prostaglandin F(2)-alpha (PG) analogues on retrobulbar blood flow velocity in previously untreated patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT), using colour Doppler ultrasound.

METHODS

Sixty newly diagnosed patients with POAG or OHT were randomly assigned to travoprost 0.004% (n = 12 with POAG, n = 8 with OHT), latanoprost 0.005% (n = 11 with POAG, n = 9 with OHT) and bimatoprost 0.03% (n = 13 with POAG, n = 7 with OHT) treatment groups in a double-masked fashion. At baseline examination, blood pressure, heart rate and intraocular pressure (IOP) were recorded. Peak-systolic and end-diastolic velocities were measured in the ophthalmic (OA), central retinal (CRA) and temporal short posterior ciliary arteries (PCA). The resistive index (RI) and ocular perfusion pressure (OPP) were determined for each treatment group. After a treatment period of 6-months, all procedures were repeated.

RESULTS

There were no significant differences in age (53 +/- 14 years in the travoprost group, 51 +/- 14 years in the latanoprost group, 53 +/- 11 years in the bimatoprost group), gender (11 men, nine women; 11 men, nine women; 13 men, seven women, by group, respectively), or clinical diagnosis (POAG or OHT) among treatment groups (p > 0.05). A significant decrease in IOP (baseline: 26.4 +/- 3.3 mmHg, 26.8 +/- 1.3 mmHg, 25.8 +/- 1.8 mmHg, respectively; month 6: 20.9 +/- 1.9 mmHg, 20.8 +/- 2.4 mmHg, 18.3 +/- 1.2 mmHg, respectively; p < 0.0001) and an increase in OPP (baseline: 33.7 +/- 3.8 mmHg, 33.5 +/- 3.2 mmHg, 33.9 +/- 2.6 mmHg, respectively; month 6: 40.2 +/- 3.5 mmHg, 39.9 +/- 3.1 mmHg, 41.7 +/- 2.6 mmHg, respectively; p < 0.0001) were verified in all three groups during the study period. Mean baseline RI values for the CRA in the travoprost group and the OA in the latanoprost group were both 0.7 +/- 0.1 mmHg and both values were statistically significantly lower at 6 months (0.6 +/- 0.1 mmHg in both groups; p = 0.002, p < 0.0001, respectively). In the bimatoprost group there was no statistically significant difference in haemodynamic parameters over the study period (p > 0.05).

CONCLUSIONS

Our results suggest that the three PG analogues significantly reduce IOP and increase OPP in patients with POAG or OHT. Topical travoprost and latanoprost significantly reduce the RI of the CRA and OA, respectively. We were unable to determine any effect of topical bimatoprost on ocular haemodynamics.

Retrobulbar haemodynamic effects of the latanoprost/timolol and the dorzolamide/timolol fixed combinations in newly diagnosed glaucoma patients

The objective of this study was to compare the effect of the latanoprost/timolol fixed combination (LTFC) and the dorzolamide/timolol fixed combination (DTFC) on the retrobulbar haemodynamic and intraocular pressure (IOP) in patents with open-angle glaucoma (OAG). This was a prospective, examiner masked, randomised and crossover study. Participants were 32 consecutive subjects, who met the inclusion/exclusion criteria, with newly diagnosed OAG. Patients were randomised to either LTFC or DTFC for the first 1-month treatment phase after a 1-month washout period, without medical treatment, patients began with the opposite treatment for the second 1-month treatment period. Colour Doppler parameters in ophthalmic artery (OA) and posterior ciliary arteries (PCA), ocular perfusion pressure, IOP and systemic haemodynamics were assessed at each baseline and at the end of each treatment period. The main outcomes include peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI) in OA and PCA. DTFC significantly increased EDV in OA from 7.55 (1.16) to 9.32 (1.22), p<0.0001, and in the PCA from 4.41 (0.70) to 5.36 (0.60), p<0.0001, and significantly decreased RI in OA from 0.775 (0.036) to 0.725 (0.032), p<0.0001, and in the PCA from 0.694 (0.045) to 0.634 (0.034). LTFC significantly decreased the EDV and significantly increased RI in PCA, p=0.0076 and p=0.0009, respectively. There were no statistical significant differences in the IOP lowering effect between both treatments. DTFC seems to have a beneficial vascular effect on retrobulbar vessels in OAG patients.

The effect of ocular hypotensive agents on macula

We evaluated the effect of long-term topical antiglaucoma drugs on the macula using the noninvasive macular visual field threshold test in 100 eyes of 75 patients with ocular hypertension or primary open-angle glaucoma. We found that topical antiglaucoma agents can alter macular sensitivity after long-term therapy and advise evaluation of the macula in glaucoma patients receiving antiglaucomatous agents.

Effects of bimatoprost 0.03% on ocular hemodynamics in normal tension glaucoma

PURPOSE

The aim of this study was to investigate the effects of bimatoprost 0.03% on ocular hemodynamics in patients with normal tension glaucoma (NTG).

METHODS

Twenty-two (22) patients with NTG were consecutively recruited. After basic eye examination and diurnal intraocular pressure (IOP) measurement, color Doppler imaging was used to measure the peak systolic and end diastolic velocities and resistive index of the central retinal, lateral posterior ciliary, and medial posterior ciliary arteries. Patients received bimatoprost 0.03% for 4 weeks, and these measurements were then repeated. The worse eye of each NTG patient was used in the statistical analysis.

RESULTS

Bimatoprost 0.03% significantly reduced mean IOP from 15.1 +/- 3.8 mmHg at baseline to 12.0 +/- 2.9 mmHg after treatment in our sample of NTG patients (P < 0.001). No significant changes in blood velocities or resistance indices were observed in the retrobulbar vessels after the 4-week treatment.

CONCLUSIONS

Topical bimatoprost 0.03% significantly reduced IOP in our NTG patients without causing significant hemodynamic changes in the retrobulbar vessels.

Comparative analysis of the effects of brimonidine and dorzolamide on ocular blood flow velocity in patients with newly diagnosed primary open-angle glaucoma

The aim of this study was to evaluate the effects of brimonidine 0.2% and dorzolamide 2% on the ocular blood flow velocity in patients with newly diagnosed primary open-angle glaucoma (POAG). Forty-four (44) patients with newly diagnosed POAG were included in a prospective, comparative, randomized clinical study. Twenty-six (26) healthy volunteers, whose age and gender matched, were recruited to compare the baseline hemodynamic characteristics of the patients. After a complete eye examination, baseline blood flow velocity measurements of the retrobulbar vessels were made with color Doppler ultrasonography. Patients were randomly assigned to receive either brimonidine 0.2% or dorzolamide 2% for a 3-month period. Blood flow velocity measurements were repeated after 3 months. Both brimonidine and dorzolamide significantly reduced the intraocular pressure. The baseline ophthalmic artery pulsatility index was higher in patients with POAG than control subjects. Whereas there was a significant increase in peak systolic velocity of the central retinal artery, no significant change was observed in the other vessels with brimonidine and dorzolamide treatment. There was little difference, in terms of ocular blood flow velocity, between newly diagnosed glaucoma patients and control subjects. Both topical brimonidine and dorzolamide significantly reduced the intraocular pressure without altering ocular blood flow velocity in patients with newly diagnosed POAG.

Compromised Autoregulatory Control of Ocular Hemodynamics in Glaucoma Patients after Postural Change

PURPOSE

The autoregulatory control of retrobulbar blood flow in response to postural challenge was investigated in normal-tension glaucoma (NTG) patients in comparison with primary open-angle glaucoma (POAG) patients and healthy volunteers.

DESIGN

Prospective cohort study.

PARTICIPANTS AND CONTROLS

Twenty POAG patients, 20 NTG patients, and 20 control subjects.

METHODS

Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistivity index (RI) in the short posterior ciliary artery (SPCA), central retinal artery (CRA) and ophthalmic artery (OA) were recorded after a change from sitting upright to a supine body position using color Doppler imaging.

MAIN OUTCOME MEASURES

Peak systolic velocity, EDV, and RI.

RESULTS

Ten minutes after postural change to a supine position, blood flow velocities in the SPCA remained unchanged in controls, whereas a significant increase of PSV and EDV was found in both glaucoma groups. The RI in the SPCA was significantly lowered in the NTG group. Recordings for the OA and CRA showed a significant increase in EDV and significant decrease in RI in all 3 groups; a significant increase in PSV in the CRA was detected only in the NTG group.

CONCLUSIONS

The unaltered flow velocities in the SPCA of healthy controls may indicate tight autoregulatory control, whereas the flow velocities in the CRA and OA appeared to follow alterations in hydrostatic pressure. In contrast, NTG and POAG patients demonstrated an insufficient compensatory response to postural change, leading to accelerated flow in the SPCA. This compromised autoregulatory control could represent another contributing factor in the pathogenesis of glaucoma.

Glaucoma progression is associated with decreased blood flow velocities in the short posterior ciliary artery

BACKGROUND

An altered perfusion of the optic nerve head has been proposed as a pathogenic factor in glaucoma.

AIM

To investigate potential differences in the ocular haemodynamics of patients having glaucoma with progressive versus stable disease, as well as healthy volunteers.

METHODS

Peak-systolic velocity (PSV), end-diastolic velocity (EDV) and resistivity index in the short posterior ciliary artery (SPCA), central retinal artery (CRA) and ophthalmic artery were recorded in 114 consecutive patients having glaucoma with an intraocular pressure (IOP) < or =21 mm Hg, as well as in 40 healthy volunteers, by colour Doppler imaging (CDI).

RESULTS

Of the 114 patients with glaucoma, 12 showed glaucoma progression (follow-up period: mean 295 (standard deviation (SD) (18) days). CDI measurements in these patients showed decreased PSV and EDV in the SPCA (p<0.001 and p<0.05, respectively) and decreased PSV in the CRA compared with patients with stable glaucoma and healthy controls (p<0.05). No differences in flow velocities were found for the ophthalmic artery. IOP and systemic blood pressure was similar in all the three groups.

CONCLUSIONS

Progressive glaucoma is associated with decreased blood flow velocities in the small retrobulbar vessels supplying the optic nerve head. The detected difference could represent a risk factor for progression of glaucomatous optic neuropathy.