The Value of Vitamins in Glaucoma
Glaucoma is a chronic, irreversible optic neuropathy that can result in serious visual disability. There is no cure, and treatment is directed at stabilizing or delaying the progression of disease. Therefore, clinicians and scientists have sought ways to prevent the onset or progression of this potentially blinding condition. Although the mechanism of glaucoma is not wholly understood, the optic neuropathy is currently thought to be caused by some combination of neurotrophic, mechanical, and vascular factors. The neurotrophic theory holds that patients with glaucoma have some genetic predisposition to nerve fiber layer cell apoptosis. The mechanical theory is that elevated intraocular pressures directly induce nerve fiber layer death. In the vascular theory, impaired perfusion of the optic nerve leads to nerve fiber layer death.
The mainstay of glaucoma treatment has been targeted at lowering the intraocular pressure through medical or surgical means because this is the only mode of therapy repeatedly shown to delay glaucoma progression. More recently, diet and lifestyle modifications have been studied as potential approaches to treatment. The antioxidant vitamins A, C, and E have gained widespread publicity in recent years, especially in ophthalmology, as a result of their promise in delaying macular degeneration. This study explored a potential association between antioxidants and glaucomatous optic neuropathy.
Unfortunately, the answers remain elusive. Wang, Singh, and Lin did not find enough evidence that supplementation with vitamins A and E was related to the self-reported prevalence of glaucoma. However, it appears that vitamin C supplementation may have a protective effect. No dose-response relationship was demonstrated, and no beneficial association was supported by serum vitamin C levels. This is relatively consistent with previous findings; therefore, these results must be further evaluated before being applied to patient care. No definitive evidence currently supports antioxidant supplementation as a means of preventing glaucoma.
The study's conclusions were further limited by the low reliability of self-reported glaucoma and the lack of classification of type and severity of disease. Participants would need a full ophthalmic evaluation, including analysis of the optic nerve and intraocular pressure measurement, to confirm diagnosis of glaucoma. Moreover, data on vitamin use were limited to a 30-day history. Long-term vs short-term vitamin supplementation might have significantly different effects on glaucoma.
The study was still notable for being a large-scale population-based analysis that included measurements of serum vitamin levels as well as adjustment for multiple confounding factors. It represents a strong initial effort to analyze the potential impact of these popular vitamin supplements on the prevention of glaucoma.
Abstract
Viewpoint
Glaucoma is a chronic, irreversible optic neuropathy that can result in serious visual disability. There is no cure, and treatment is directed at stabilizing or delaying the progression of disease. Therefore, clinicians and scientists have sought ways to prevent the onset or progression of this potentially blinding condition. Although the mechanism of glaucoma is not wholly understood, the optic neuropathy is currently thought to be caused by some combination of neurotrophic, mechanical, and vascular factors. The neurotrophic theory holds that patients with glaucoma have some genetic predisposition to nerve fiber layer cell apoptosis. The mechanical theory is that elevated intraocular pressures directly induce nerve fiber layer death. In the vascular theory, impaired perfusion of the optic nerve leads to nerve fiber layer death.
The mainstay of glaucoma treatment has been targeted at lowering the intraocular pressure through medical or surgical means because this is the only mode of therapy repeatedly shown to delay glaucoma progression. More recently, diet and lifestyle modifications have been studied as potential approaches to treatment. The antioxidant vitamins A, C, and E have gained widespread publicity in recent years, especially in ophthalmology, as a result of their promise in delaying macular degeneration. This study explored a potential association between antioxidants and glaucomatous optic neuropathy.
Unfortunately, the answers remain elusive. Wang, Singh, and Lin did not find enough evidence that supplementation with vitamins A and E was related to the self-reported prevalence of glaucoma. However, it appears that vitamin C supplementation may have a protective effect. No dose-response relationship was demonstrated, and no beneficial association was supported by serum vitamin C levels. This is relatively consistent with previous findings; therefore, these results must be further evaluated before being applied to patient care. No definitive evidence currently supports antioxidant supplementation as a means of preventing glaucoma.
The study's conclusions were further limited by the low reliability of self-reported glaucoma and the lack of classification of type and severity of disease. Participants would need a full ophthalmic evaluation, including analysis of the optic nerve and intraocular pressure measurement, to confirm diagnosis of glaucoma. Moreover, data on vitamin use were limited to a 30-day history. Long-term vs short-term vitamin supplementation might have significantly different effects on glaucoma.
The study was still notable for being a large-scale population-based analysis that included measurements of serum vitamin levels as well as adjustment for multiple confounding factors. It represents a strong initial effort to analyze the potential impact of these popular vitamin supplements on the prevention of glaucoma.
Abstract