Looking beyond IOP when managing glaucoma patients

Supplemental treatments, such as Ginkgo biloba and a host of other antioxidants, can help address the systemic sources of ocular nerve damage and help to improve blood flow to the eye.

Glaucoma, as one of the leading causes of blindness and currently affecting up to four million Americans, is a general name given to a group of optic neuropathies characterized by the degeneration of the optic nerve, and age, race, family history, and elevated IOP are widely known risk factors for the disease.

While high IOP is currently the only modifiable risk factor, 15% to 30% of persons with ocular hypertension never develop glaucoma pathology, and conversely, patients with acceptable IOP still sustain ocular nerve damage.

Despite significant strides in diagnostic technology and advanced clinical treatment modalities, there are still many questions as to the causal root of glaucoma. Prevalent glaucoma management protocols aim to reduce and control IOP levels but may neglect to address the systemic sources of ocular nerve damage.

Blood health in ocular health

Compromised vascular function, both systemic and locally, has long been linked to open-angle glaucoma (OAG). Low systemic blood pressure has been correlated to low tension glaucoma and increased visual field loss in OAG. Diseases indicative of defective vasoregulation, such as Raynaud’s phenomenon and migraines, have also been correlated to normal tension glaucoma.

A 2009 consensus paper and subsequent corroborative studies point to decreased cerebrospinal fluid pressure (CSFP) as a contributing factor of ocular nerve damage.

The Leuven Eye Study sought to narrow down what vascular data can be used for disease stratification and found that glaucoma patients had higher ocular perfusion pressure, lower retrobulbar velocities, higher retinal venous saturation and higher choroidal thickness asymmetry as compared to healthy eyes.

The Leuven Eye Study built upon previous evidence suggesting that impaired vascular autoregulation renders the optic nerve head susceptible to ischemic damage, which likely contributes to further impairment in autoregulation and changes to the optic nerve head.

The secondary changes to ischemic damage may then begin a cascade of toxic by-products and free radicals that further deteriorate the health of the eye.

While it has not yet been established that maintaining or enhancing ocular blood flow will prevent glaucoma or slow its progression, there is certainly much scientific data pointing to a positive theoretical relationship between adequate nutrient delivery and the health of retinal ganglion cells.

Nutrition and blood flow

Since improving ocular blood flow is not a treatment for nerve damage, but rather a potentially preventative therapy, it is a prime space to consider nutritional dietary supplementation. Limited studies have investigated the ability of the antioxidant Ginkgo biloba to improve ocular blood flow. Other antioxidants, anthocyanins and anthocyanidins, have been shown to increase optic nerve head and retinal blood flow, as well as slow visual field deterioration and influence ophthalmic function in other ways.

A recent study examined the effects of a nutritional dietary supplement (Optic Nerve Formula, ScienceBased Health) on retinal and retrobulbar blood flow in patients with open angle glaucoma (OAG). The study, a double blind, randomized, placebo control crossover study of nutritional supplements, was the most rigorous study to date. Previous studies of nutritional supplements were observational pilot studies focused on normal-tension glaucoma and healthy subjects.

Study participants included 45 people with confirmed OAG who were given active or placebo treatment for one month followed by washout and switched treatments.

Nutritional supplementation produced statistically significant improvements over placebo in: peak systolic and/or end diastolic blood flow velocities in all retrobulbar blood vessels, vascular resistance in the central retinal and nasal short posterior ciliary arteries, superior and inferior temporal retinal capillary mean blood flow, and the ratio of active to nonactive retina capillaries.

The study concluded that one-month oral administration of antioxidants produced increases in biomarkers of ocular blood flow within retinal and retrobulbar vascular beds and suggests that daily supplementation with certain antioxidants over a period of at least one month may improve retinal capillary perfusion in patients with OAG.

Integrating nutrition into clinical practice

Nutrition is increasingly gaining recognition among physicians and patients for its role in our overall health, and there is precedence for the efficacy of vitamins in ophthalmology.

While nutraceutical therapy is not an approved therapy, but an adjunct therapy, I frequently introduce it to my patients.

I explain that glaucoma is a disease that is primarily nerve damage due to one or several different causes. One of those causes could be pressure that is too high for their eyes, and that I will do what I can to bring that pressure down.

However, decreasing the pressure may not be enough to protect the nerve, but we can provide better nutrients to potentially help the blood supply and reduce inflammation very safely with oral antioxidant supplements.

I strongly recommend my patients use a product with scientifically backed ingredients, like bilberry extract, which are safe to take in conjunction with other medications and in individuals with fluctuating blood pressures. Patients leave my office with the understanding that there is virtually no downside, and that supplementation is an additional approach we can take to protect the nerve.

I am not comfortable sending patients out to purchase a generic supplement and only recommend well-studied supplements, such as the product used in the study, that adhere to strict quality control and consistency of makeup.

While much more study and clinical experience remains to be done on nutraceuticals, we have the ability to potentially improve vascular regulation and blood flow to the eye and reduce oxidative stress in a completely harmless and cost-effective manner.

If we have patients with blood flow related risk factors, I do feel it is important to educate them that there is an objectively studied supplement from which they may benefit.

As physicians, we can feel good knowing we have offered another pathway to protect precious nerve cells.

Disclosures:

Inder Paul Singh, MDE: ipsingh@amazingeye.com Dr. Singh is a glaucoma specialist practicing at The Eye Centers of Racine and Kenosha in Wisconsin. He did not indicate any proprietary interest relevant to the subject matter.