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Glaucoma

 

Glaucoma Introduction

Glaucoma is a group of conditions characterized by progressive damage to the eye from increased pressure within the eye, termed intraocular pressure. [1] It is a common cause of blindness. Approximately 2 million Americans are affected with this group of disorders, but as much as twenty five percent of cases remain undetected and undiagnosed. [2] Glaucoma generally affects the elderly. However, there are specific types of glaucoma, like juvenile and congenital glaucoma, which can occur in children.

Glaucoma is, largely, the result of high intraocular pressure. However, it does not appear in everyone who has this condition. Only one percent of patients who have been diagnosed with ocular hypertension will also be subsequently diagnosed with glaucoma. [1] When elevated intraocular pressure causes damage to the inner structures of the eye, including ntercellular epithelial edema (swelling) of the cornea, corneal scarring, necrosis (tissue death) of the iris, ciliary body stroma, and venous stasis of the retina, only them is it diagnosed as glaucoma. [3]

There are two main classifications of glaucoma: open-angle and closed angle (or angle-closure). These categories refer to the way in which aqueous outflow is obstructed. [1]

  • In open angle glaucoma, there is poor transport of aqueous humor (fluid in the eye) through the angle in the anterior chamber of the eye. Even though this angle is open, the inadequate outflow leads to elevated pressure in the eye. This type accounts for 60-70% of cases of glaucoma.
  • Closed angle glaucoma refers to an angle that is obstructed, thereby preventing adequate outflow, resulting in the same elevation in intraocular pressure.
  • Furthermore, some patients suffer from glaucoma that is termed “normal or low pressure glaucoma,” in which case the measured intraocular pressure is in the normal range but for some reason in these patients, the pressure is too high and they develop glaucoma.
  • Glaucoma can also be categorized by etiology. Factors influencing this categorization include; developmental glaucoma, glaucoma associated with inflammation or injury, and glaucoma following intraocular surgery.

In addition, glaucoma can be acute (sudden onset) or chronic. The majority of cases are chronic. Persons at a higher risk of developing open-angle glaucoma include, as mentioned before, the elderly, African-Americans, diabetics, those with a family history of the disorder, persons who suffer from hypertension (high blood pressure), use corticosteroids, or have myopia. [1]

Glaucoma Symptoms

  • Chronic open-angle glaucoma is characterized by a slow progressive loss of peripheral vision and later central vision. There are no early warning signs because by the time an individual starts demonstrating symptoms, damage has already occurred. Both eyes are usually affected, however one may develop symptoms at a slower rate than the other. These patients may express to their physician symptoms including; impaired night vision, seeing halos around lights, mild headaches, frequent changes in lenses, and vague visual disturbances.
  • A patient with chronic angle-closure glaucoma generally has no signs and symptoms until they experience an attack. Usually only one eye is affected. The course of this condition involves recurrent attacks that start with seeing halos around lights, pain in the eye or head, and episodes of diminished visual acuity (not being able to see clearly). These events are then followed by an attack, characterized by rapid loss of sight and sudden severe throbbing pain (often in only one eye), nausea, vomiting, tearing, and intense redness. These attacks are also characteristic of acute angle-closure glaucoma, however these attacks are more severe and occur more suddenly. Acute angle-closure glaucoma is a medical emergency and requires immediate attention, due to the potentiality of permanent blindness.

Glaucoma Treatment

Depending on the type of glaucoma a patient is suffering from, treatment will vary. In the case of acute angle-closure glaucoma (a medical emergency), treatment must be initiated immediately to prevent permanent vision loss. In this case, the patient must always be treated medically and should not attempt to use natural therapies or nutritional supplements. They must be treated with topical beta-blockers, IV, or oral carbonic anhydrase inhibitors, and topical alpha-2-selective adrenergic agonists.

Conventional treatment for Chronic Open-Angle Glaucoma:

The goal of treatment is to prevent any further damage to the optic nerve and visual fields by reducing the intraocular pressure [1]. Prescription medications are used to treat this condition, as well as laser therapy. If both of these modalities are ineffective, filtration surgery may be performed, or may be used initially depending on the individual’s condition. There are an increasing number of medications available for treatments, including: miotics (pilocarpine and physostigmine) that increase aqueous outflow, carbonic anhydrase inhibitors (methazolamide), beta-blockers (timolol and metipranolol0, which which work decrease aqueous production; and osmotic diuretics (oral glycerin or IV mannitol) that draw fluid out of the eye by osmosis.

Conventional treatment for Chronic Closed-Angle (Angle-Closure) Glaucoma: As discussed, for acute closed-angle glaucoma, treatment must be initiated immediately for an attack. The definitive treatment for these patients is laser peripheral iridotomy, which has an extremely low incidence of complications.

Supplements helpful for Glaucoma

Vitamin C Vitamin C has been shown to be useful for the treatment of high intraocular pressure, typical in patients with glaucoma. [4] High dose vitamin C, anywhere from 1-35 grams per day (with an average of 10g/day), was administered orally to patients with intraocular pressure exceeding 20mmHg. Patients were instructed to take vitamin C to bowel tolerance (until stool became loose) in 3 daily doses with meals. All patients in the study demonstrated a reduction in intraocular pressure, with a mean reduction of 5.6 mmHg. Another study also showed a smaller reduction in intraocular pressure with lower doses (2 grams/day) of prescribed Vitamin C. [5]

Magnesium aspartate Magnesium aspartate hydrochloride was administered to patients with primary open-angle glaucoma and normal-tension glaucoma over a course of 4 weeks. [6] These patients took 250mg/per day in equally divided doses. This administration resulted in an improvement of visual field defects. The authors suggest that this specific form of magnesium exerts its effect via a vasodilatory action, thereby improving blood flow to the eye, which leads to improved vision.

Flavonoids Flavonoids are compounds found in colored fruits and vegetables that assist with collagen stabilization. Flavonoids also synergize the effects of vitamin C, therefore could be taken to augment the effect of vitamin C noted in the section above. Furthermore, a specific flavonoid called rutin, has shown effectiveness in reducing intraocular pressure when combined with prescriptive miotic agents. This result occured in patients who were unresponsive to the medication alone. [7] Patients took 20mg of rutin three times a day for 4 weeks. The effect of the flavonoid is thought to be due to a reduction in excessive permeability of the blood aqueous membrane within the eye.

Essential fatty acids Essential fatty acids, specifically the omega 3-type found in fish oils (docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have a body of evidence in animal studies and human epidemiology to support their use for the treatment of chronic open angle glaucoma. One mammalian study demonstrated a reduction in intraocular pressure when cod liver oil was administered in both oral and intramuscular solutions. [8]

Lipoic acid Lipoic acid is vitamin like substance that contains sulfur and has a role in cellular energy production (ATP). Its use for treating stage I and II open-angle glaucoma has been studied in various controlled settings. [9] Patients were prescribed either 75 mg of lipoic acid daily for two months or 150mg for one month. Improvement was measured in almost half of the participating subjects, more so in those with stage II glaucoma. Specifically, there were improvements in visual acuity, various biochemical parameters, and the coefficient of liquid discharge. These results were more significant in patients receiving the higher dosage (150mg daily).

Gingko biloba Gingko extracts have demonstrated effectiveness in the treatment of glaucoma. [10] The extract must contain a minimum of 25% gingko flavonglycosides, which are a category of active constituents found in this herb. Patients in one study, suffering from severe glaucoma, took 160mg per day of the extract for four weeks and then 120mg daily. The results of the study showed improvements in intraocular pressure and visual field defects. This study was promising, that such a severe categorization of glaucoma responded to this particular herbal extract.

References

1. Merck Manual of Diagnosis. Merck Research Laboratories, Whitehouse Station, NY, 1999: 512-514.

2. Tierney LM et al. Current Medical Diagnosis and Treatment. Lange Medical Publications, Los Altos, CA 1997;183-186

3. Robbins et al. Pocket Guide to Robbins Pathologic Basis of Disease, 6th Ed. WB Saunders Company, Philadelphia, PA 1999; 668-669.

4. Boyd HH. Eye pressure lowering effect of Vitamin C. J Orthomolec Med 1995;10:165-168.

5. Linner E. The pressure lowering effect of ascorbic acid in ocular hypertension. Acta Ophthalmologica 1969;47:685-689.

6. Bittner SB, et al. A double blind randomized placebo controlled trial of fish oil in psoriasis. Lancet 1988;1:378-380.

7. Stocker F. New Ways of Influencing the Intraocular Pressure. NY St J Med 1949;49:58-63.

8. Appel LJ et al. Does Supplementation of Diet with Fish Oil Reduce Blood Pressure? A Meta-Analysis of Controlled Clinical Trials. Arch Int Med 1993;47:1429-1438.

9. Filina AA et al. Lipoic acid as a means of metabolic therapy of open-angle glaucoma. Vestn Oftalmol 1995;111(4):6-8.

10. Merte HJ and Merkle W. Longterm treatment with Gingko biloba extract of Circulatory Disturbances of the Retina and Optic Nerve. Klin Monatsbl Augenheilkd 1980;177(5):577-583.