Polyphenols Bolster Drug Effects in Ocular Hypertension

Ocular Hypertension and Risk of Glaucoma

Ocular hypertension is a leading risk factor for the development of primary open angle glaucoma (POAG), and is the only modifiable risk factor acknowledged at present.

It’s estimated that 4 to 7% of Americans over 40 years of age have ocular hypertension. The Ocular Hyper-tension Treatment Study (OHTS) clearly showed that lowering IOP is effective in delaying or preventing the onset of POAG in individuals with ocular hypertension. Recent results from a long-term study by the OHTS group indicates that those at high risk of POAG can benefit from early preventive treatment (1).

Spurred by previous findings that a combination of polyphenols (anthocyanins and procyanidins) could improve IOP and blood flow in ocular hypertension, the same researchers recently compared the effects of those polyphenols alone and with latanoprost in ocular hypertensive patients with no signs of POAG (2).

Study Design

The study recruited 79 men and women, mean age 49 yrs, with diagnosed elevated IOP (> 35 and < 40 mmHg). All subjects had complete eye exams, showing no signs of POAG. Patients were randomly divided into 3 groups to receive latanoprost (Xalatan, one drop per eye daily), one tablet of the polyphenol combination, or both.

The supplement tablet contained a daily dose of about 28 mg anthocyanins (Bilberry extract) and 28 mg procyanidins (French Maritime Pine Bark Extract). IOP was consistently measured at the same time in the a.m. by the same investigator, and in triplicate. High resolution color Doppler imaging was used to measure the peak systolic flow velocity, and the end diastolic flow velocity of the central retinal artery.

Results

• The polyphenol supplement alone lowered IOP from 38.1 at baseline to 29.0 mmHg after 16 weeks, with little further improvement during the following 8 weeks.
• Latanoprost rapidly lowered IOP from baseline 37.7 to 27.2 mmHg within 4 weeks, without further effects.
• The combined supplement and latanoprost lowered IOP from 38.0 to 27.3 mmHg after 4 weeks, and further reduced IOP to 24.2 mmHg after 6 weeks.
• After 24 weeks, IOP with the combination treatment (23.0 mmHg) was significantly lower than with the topical drug alone (27.2 mmHg). [See graph below]

• The supplement and latanoprost each gradually increased central artery blood flow in a comparable manner. From 12 weeks on, the diastolic component was higher with the combined vs. individual treatments.
  
  

Comments

The polyphenol and drug combination was more effective for lowering IOP, and the combination yielded better retinal blood flow. Evidence suggests that bilberry anthocyanins may act by countering increased permeability of blood capillaries, while the procyanidins may improve endothelial function. These promising results warrant further research with a larger patient group, according to the authors.

References

1. Kass MA, et al. Delaying Treatment of Ocular Hypertension. The Ocular Hypertension Treatment Study. Arch Ophthalmol 128:276-287, 2010.
2. Steigerwalt RD, et al. Mirtogenol® potentiates latanoprost in lowering intraocular pressure and improves ocular blood flow in asymptomatic subjects. Clinical Ophthalmol 4:471-6, 2010.