Importance of Vitreous Liquefaction in Age-Related Cataract

Harocopos, George J.; Shui, Ying-Bo; McKinnon, M. H.; Holekamp, Nancy M.; Gordon, Mae O.; Beebe, David C.

doi:10.1167/iovs.03-0820

Cited by 130 publications

(108 citation statements)

References 56 publications

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“…Previous studies found that degeneration of the vitreous body was associated with increased nuclear opacification [38,42]. The state of the vitreous gel was not related to the occurrence of either cortical or posterior subcapsular opacities, the other two main types of age-related cataracts.…”

Section: The Mechanisms That Maintain the Low-oxygen Environment Aroumentioning

confidence: 78%

“…Since the vitreous gel does not regenerate, vitrectomy permanently alters the physical state of the material in the vitreous chamber. When the vitreous gel is removed, movement of the head or eyes will cause circulation and mixing of the fluid in the vitreous chamber [38,39]. Mixing of the vitreous fluid carries oxygen away from the surface of the retina and distributes it throughout the vitreous chamber (figure 2b).…”

Section: The Mechanisms That Maintain the Low-oxygen Environment Aroumentioning

confidence: 99%

“…Studies that measured the extent of vitreous degeneration in the eyes of older subjects found that some eyes in a given age group had extensive vitreous liquefaction, while others had a nearly intact vitreous gel [32,38,44]. If the gel state of the vitreous is important to protect the lens from nuclear cataract by minimizing its exposure to oxygen, the factors responsible for the liquefaction of the vitreous are important risk factors for nuclear cataract formation.…”

Section: The Mechanisms That Maintain the Low-oxygen Environment Aroumentioning

confidence: 99%

“…We previously showed that degeneration of the vitreous body is an important risk factor for nuclear opacification [38]. Degeneration of the vitreous body is also an underlying cause of retinal detachment, macular hole, vitreomacular traction syndrome and other retinal problems.…”

Section: Would Lowering the Oxygen In The Vitreous Protect The Lens Fmentioning

confidence: 99%

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Vitreoretinal influences on lens function and cataract

Beebe

Holekamp

Siegfried

et al. 2011

Phil. Trans. R. Soc. B

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The lens is composed of a thin metabolically active outer layer, consisting of epithelial and superficial fibre cells. Lying within this outer shell are terminally differentiated, metabolically inactive fibre cells, which are divided into an outer cortex and central nucleus. Mature fibre cells contain a very high protein concentration, which is important for the transparency and refractive power of the lens. These proteins are protected from oxidation by reducing substances, like glutathione, and by the low-oxygen environment around the lens. Glutathione reaches the mature fibre cells by diffusing from the metabolically active cells at the lens surface. With age, the cytoplasm of the nucleus becomes stiffer, reducing the rate of diffusion and making nuclear proteins more susceptible to oxidation. Low pO 2 is maintained at the posterior surface of the lens by the physical and physiological properties of the vitreous body, the gel filling the space between the lens and the retina. Destruction or degeneration of the vitreous body increases exposure of the lens to oxygen from the retina. Oxygen reaches the lens nucleus, increasing protein oxidation and aggregation and leading to nuclear cataract. We suggest that maintaining low pO 2 around the lens should prevent the formation of nuclear cataracts.

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Section: The Mechanisms That Maintain the Low-oxygen Environment Aroumentioning

confidence: 78%

Section: The Mechanisms That Maintain the Low-oxygen Environment Aroumentioning

confidence: 99%

Section: The Mechanisms That Maintain the Low-oxygen Environment Aroumentioning

confidence: 99%

Section: Would Lowering the Oxygen In The Vitreous Protect The Lens Fmentioning

confidence: 99%

See 2 more Smart Citations

Vitreoretinal influences on lens function and cataract

Beebe

Holekamp

Siegfried

et al. 2011

Phil. Trans. R. Soc. B

Self Cite

View full text Add to dashboard Cite

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“…This view is supported by former observations demonstrating the rapid development of cataract under conditions of high oxygen load in humans treated by hyperbaric oxygen [42]. Oxygen is also believed to be one of the potential causative agents for the development of nuclear cataract following vitrectomy [43,44]. Under normal clinical circumstances the effects of oxygen-load accumulate over many years of exposure to relatively low oxygen loads.…”

Section: Resultsmentioning

confidence: 76%

Antioxidants Prevention of Diabetic Damage in the Organ Culture Bovine Lenses

Dovrat¹

2012

Metabolomics

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Oxidative stress represents a mechanism which could lead to diabetic cataract. We exposed bovine lenses in culture conditions for two weeks to high glucose concentration (450 mg%) and investigated the damage to the lens and possible protection by special antioxidants -N-acetyl-L-cysteine (NAC) and the zinc complex of desferrioxamine (DFO), a selective chelator for iron. We monitored the optical quality of the lenses and the oxidation of the epithelium with dichlorofluorescein (DCF) assay, as well as the changes in lens proteins profile by 2D gel electrophoresis. Under high glucose changes in lens focal length, increased oxidation, and changes in lens crystalline were observed. NAC and Zn-DFO nearly completely protected the lenses; DFO showed only partial protection. The results demonstrated that antioxidants should be considered as treatment modality protecting the lens from high glucose damage. It is proposed that a combination of NAC and Zn/DFO could prove highly efficient.the presence of high glucose concentrations (450 mg %), mimicking the diabetic state, and examined the protection bestowed by the DFO complexes and NAC, on the injurious processes on the lenses. We used a unique system of intact bovine lenses, maintained for a longterm, under culture conditions. This system allows for direct exposure to a pre-set glucose concentration, and monitoring the effects on lens transparency with a highly sensitive optical method [20]. The system can detect early optical damage to lenses, which cannot be detected by other methods often used. At the completion of the culture period lens epithelium and lens proteins were analyzed.It was anticipated that the extent of protection exerted on the lens, in this system, will be indicative of the involvement of iron as a catalyst and of free radicals as causative agents, in the damage to the diabetic lens. Materials and Methods Lens organ culture systemLenses were excised in a delicate operation from eyes obtained from 1-year-old male calves under sterile conditions, 2-4 hours after enucleating. From each animal one eye is used for experimental treatment and the other eye serves as control. Each lens is placed in a specially designed culture container, which we have developed [21]. The culture medium consists of M199 with Earl's balanced salt solution, supplemented with 5.96g/L HEPES, 3% dialyzed fetal calf serum and antibiotics (penicillin 100 U/ml and streptomycin 0.1 mg/ ml). Our intact lens culture system mimics the lens conditions inside the eye and makes it possible to keep lenses for long-term studies for

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