Dr. Grossman’s Blog

Researchers tie blood pressure and ocular perfusion pressure to glaucoma

Although intraocular pressure (IOP) is considered a primary risk factor for the development of glaucoma, there is evidence to suggest that glaucoma may continue to progress despite lowering patients’ IOP to targeted levels.

Several recent studies point to vascular risk factors in the development of glaucoma. This new research indicates that blood pressure (BP) and ocular perfusion pressure have become increasingly important in understanding and treating glaucoma.

Although doctors cannot currently visualize ocular blood flow directly, they can easily measure glaucoma patients’ BP and IOP to calculate their ocular perfusion pressure and quantify the vascular changes.

An article published in the British Journal of Ophthalmology explores the relationships between BP and IOP, BP and glaucoma, and perfusion pressure and glaucoma. Study authors suggest that ocular perfusion pressure and its fluctuation may be parameters that need to be measured in the treatment of glaucoma patients.

Learn more about glaucoma, including self-help tips

SOURCE: Blood Pressure and Glaucoma, Costa, et al, Br J Ophthalmol, 30 March 2009, doi:10.1136/bjo.2008.149047.

Researchers from Tufts University have created a model to better predict a person’s risk for Age-related Macular Degeneration (AMD). 

This study, published in the May issue of Investigative Ophthalmology and Visual Science, was based on data from the 1,446 participants in the Age-Related Eye Disease Study (AREDS).  It shows how genetic, ocular, and environmental variables were evaluated and predictive models for prevalence and incidence of AMD were assessed. 

Researchers evaluated six criteria:

• age,
• sex,
• education,
• smoking status,
• body mass index, and
• supplementation with high-dose formulation of antioxidants and zinc (to slow progression of the AMD).

Although genetics play a large part in who will get AMD, there are lifestyle choices that can greatly influence a person’s risks for AMD.  Dr. Seddon noted that among individuals with one genotype studied (homozygous C3 risk genotype), the chance of suffering from the advanced form of AMD increased from approximately three times the risk for nonsmokers to almost 10 times the risk for smokers.

Study authors hope that learning more about how to predict who is at risk for AMD will give doctors and patients better information about how to better treat and even help prevent AMD.

Learn more about AMD and AMD prevention self-help tips

SOURCE:  Prediction Model for Prevalence and Incidence of Advanced Age-Related Macular Degeneration Based on Genetic, Demographic, and Environmental Variables, Seddon, et al, Investigative Ophthalmology and Visual Science. 2009;50:2044-2053.

Antioxidant and omega-3 supplements continue to be a simple, low-cost, effective therapy for AMD

A study designed to measure changes in visual function in subjects with atrophic (dry) age-related macular degeneration (AMD) found that three-quarters of the subjects receiving a nutritional supplement demonstrated stabilization or improvement of visual acuity at 6 months.

Dry, atrophic, or non-exudative, AMD is the most common form of macular degeneration.  Risk factors for dry AMD include:

• age greater than 50
• Caucasian race
• poor nutrition
• smoking
• atherosclerotic vascular disease
• genetics 
• sunlight exposure.

Multiple studies have suggested that nutritional factors can play a significant role in slowing the onset or limiting the effects of AMD.  The Taurine, Omega-3 Fatty Acids, Zinc, Antioxidant, Lutein (TOZAL) study tried to identify the potential benefits of a new supplement designed to limit the risk of AMD and progressive vision loss.

In this study, published in BMC Ophthalmology, 37 mixed gender patients (average age 76 years) at 5 independent study sites received a nutritional supplement specifically formulated to combat AMD.   This supplement included natural beta-carotene, vitamins A and E, zinc, and copper.   Results were compared to subjects in other tests who had been given placebos.

76.7% of subjects receiving the nutritional supplement demonstrated stabilization or improvement of visual acuity at 6 months.

Read other studies about AMD

Learn more about antioxidants and food sources for nutrients important for good eye health

SOURCE:  TOZAL Study: An open case control study of an oral antioxidant and omega-3 supplement for dry AMD, Cangemi, BMC Ophthalmology 2007, 7:3doi:10.1186/1471-2415-7-3.

Age-related macular degeneration (AMD) is the leading cause of vision loss in aging Western populations.   A study measuring the benefits of lutein found that consuming lutein nutritional supplements improves visual function and symptoms in those suffering from AMD.

90 participants with AMD participated in a trial conducted at a midwestern Veterans Administration Hospital from August 1999 to May 2001.

For 12 months, patients in Group 1 received lutein supplements; in Group 2, a lutein plus an antioxidant/vitamin/mineral supplement; and in Group 3, a placebo.

Researchers found that participants in groups 1 and 2 displayed improvements in mean eye macular pigment optical density, visual acuity, and contrast sensitivity.  Patients who received the placebo had no significant changes in any of the measured findings.

The study authors concluded that visual function is improved with lutein alone or lutein together with other nutrients.

Lutein is a naturally occurring carotenoid, and is found in green leafy vegetables such as spinach and kale.

Learn more about lutein and other nutrients important for good eye health

Read more about macular degeneration (AMD)

SOURCE:  Double-masked, placebo-controlled, randomized trial of lutein and antioxidant supplementation in the intervention of atrophic age-related macular degeneration: the Veterans LAST study (Lutein Antioxidant Supplementation Trial), Stiles, et al, Optometry. 2004 Apr;75(4):216-30.

Researchers predict age-related macular degeneration (AMD) will increase substantially by 2050, as the U.S. population ages, but the use of new and existing therapies can mitigate the effects of the condition.

A significant preventative therapy named in this study is the use of antioxidant vitamins to slow the progression of AMD from early to late stages.  Other treatments reviewed include laser and photodynamic therapies and anti-VEGF injections.

Scientists from the Research Triangle Institute International in North Carolina simulated cases of early AMD, choroidal neovascularization (CNV), geographic atrophy (GA), and AMD-attributable visual impairment and blindness with 5 universal treatment scenarios:

1. no treatment;
2. focal laser and photodynamic therapy (PDT) for CNV; 
3. vitamin prophylaxis at early-AMD incidence with focal laser/PDT for CNV; 
4. no vitamin prophylaxis followed by focal laser treatment for extra and juxtafoveal CNV and anti-vascular endothelial growth factor treatment; and 
5. vitamin prophylaxis at early-AMD incidence followed by CNV treatment, as in scenario 4.

From the results of this analysis, the researchers predicted that cases of early AMD will increase from 9.1 million in 2010 to 17.8 million in 2050 across all scenarios, but that existing medical therapies have the potential to reduce the visual impairment and blindness attributable to AMD by as much as 35 percent, translating to 565,000 fewer cases of visual impairment and blindness in 2050.

Learn about good food sources of antioxidants

Read about antioxidant vitamins important in the treatment of macular degeneration

SOURCE:  Forecasting age-related macular degeneration through the year 2050: the potential impact of new treatments, Rein, et al,  Arch Ophthalmol. 2009 Apr;127(4):533-40.

Although individuals with age-related macular degeneration (AMD) lose central vision, their peripheral vision often remains intact.   The Macular Disease Society (based in the UK) has developed a training scheme to help people use the undamaged parts of their eyes to read and identify faces. 

According to their research, people can be taught to use their peripheral vision to compensate for damage to their central vision, using “eccentric viewing” and “steady eye techniques”.   When someone with central vision loss looks directly at an object it may disappear or appear distorted, but when they look above, below, or to one side of it, they see it more clearly.

Eccentric viewing helps people learn where to focus their gaze to make their vision better.  Once this position is identified, they can be taught how to read again using the steady eye technique:  instead of moving the eyes from left to right to read a sentence, the person can keep their eyes completely still and move the text to the left so that each word in turn moves into the area of best vision.

Learn more about macular degeneration

SOURCE:  BBC News Channel, April 10, 2009, http://news.bbc.co.uk/1/hi/health/7958838.stm

A small study by Japanese researchers demonstrates an increased blood supply to the retina upon stimulation of certain acupuncture points. Needles were inserted near the posterior base of the thumbs of volunteers while investigators used a laser to scan the retinal blood flow. Both volume and velocity increased in these patients. The work was done at the ophthalmology department at Kyoto Prefectural University of Medicine.

Reported by Dr. Kazuhiko Mori at the annual meeting of the Association for Vision and Ophthalmology in Fort Lauderdale this past May.

For more related information on natural eye care, go to www.naturaleyecare.com