Suppression of Post-Vitrectomy Lens Changes in the Rabbit by Novel Benzopyranyl Esters and Amides

Kuszak, J.R.; Sivak, J. G.; Moran, K.L.; Scheib, Sally A.; Garner, William H.; Ke, Tai-Lee; Hellberg, Mark R.; Graff, Gustav

doi:10.1006/exer.2002.2043

Cited by 6 publications

(5 citation statements)

References 56 publications

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“…They suggest that nuclear sclerosis may then be the result of the transient loss of the protective influence of the cortex during formation of the initial PSC. 76,78 Hsuan et al in 2001 67 hypothesized that the cortex and epithelium actively sustain the nuclear fibers, and when this protective role is lost after vitrectomy with tamponade, the environment of the nuclear crystallins changes with subsequent posttranslational modification and nuclear cataract formation. Chung et al in 2001 11 also observed that posterior vitrectomy induced uveitis may be related to posterior subcapsular cataracts after vitrectomy.…”

Section: Formation Postvitrectomymentioning

confidence: 98%

“…The aqueous humor of rabbits that underwent partial vitrectomy showed postsurgical accumulation of PGE 2 and breakdown of blood-ocular barriers 76,77 resulting in inflammatory cells, enhanced free radical generation, and recruited leukocytes that consequentially may overwhelm the normal cellular defense system of the lens epithelium. In their study, Kuszak et al 76 found that the use of a surgical irrigating solution containing a novel benzopyrene analog, an antiinflammatory agent that suppresses free radical formation and inflammatory cytokine synthesis, proved beneficial in attenuating and preventing vitrectomy-induced formation of abnormal posterior lens suture. They suggest that nuclear sclerosis may then be the result of the transient loss of the protective influence of the cortex during formation of the initial PSC.…”

Section: Formation Postvitrectomymentioning

confidence: 99%

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Competing Theories of Cataractogenesis After Pars Plana Vitrectomy and the Nutrient Theory of Cataractogenesis: A Function of Altered Aqueous Fluid Dynamics

Ling¹,

Weiter²,

Buzney³

et al. 2005

International Ophthalmology Clinics

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Glaucoma and vitreoretinal surgeries have long been associated with cataract progression. 1-10 There have been many theories to explain this phenomenon. These theories include direct or indirect mechanical damage from instrumentation, light toxicity from the operating scope, intraocular irrigating solution, use of intraocular gas, intraocular inflammation, and advanced patient age. 11,12 These theories, however, do not distinguish between the different types of cataracts that form postoperatively, nor do they provide a unified coherent explanation for the observed cataract progression. In this chapter, we propose a mechanism of cataractogenesis, specifically nuclear sclerosis formation, which we believe occurs as a function of altered aqueous fluid dynamics after intraocular surgery. We present this as the nutrient theory of cataractogenesis.Before detailed discussion of the nutrient theory of cataractogenesis as a function of altered aqueous fluid dynamics, a background review of the following concepts will serve as a vital conceptual framework for its understanding: 1) anatomy and metabolism of the lens, 2) aqueous humor and vitreous biochemistry, 3) fluidics of the aqueous humor and vitreous, 4) types of cataracts, 5) recognized causes of cataracts, and 6) current theories of nuclear sclerosis formation after pars plana vitrectomy. 173

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Section: Formation Postvitrectomymentioning

confidence: 98%

Section: Formation Postvitrectomymentioning

confidence: 99%

Competing Theories of Cataractogenesis After Pars Plana Vitrectomy and the Nutrient Theory of Cataractogenesis: A Function of Altered Aqueous Fluid Dynamics

Ling¹,

Weiter²,

Buzney³

et al. 2005

International Ophthalmology Clinics

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“…The precise variation in the amount of fiber end flare and opposite end curvature necessary to create the different suture types is well documented (Kuszak, 1995a). In addition, both the effect of different suture types on lens optical quality, and the negative effects of abnormal sutural anatomy as a consequence of both naturally occurring and experimentally induced pathology on lens function is calculable (Kuszak et al, 1991, 1994, 1999, 2000, 2002; Sivak et al, 1994; Al‐Ghoul et al, 1998, 1999). However, the factors that direct the exact arrangement of fibers into the form that follows function, and are compromised such that malformation leads to malfunction, are not known.…”

mentioning

confidence: 99%

Lens structure in MIP‐deficient mice

et al. 2003

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In this study we used correlative light, scanning, and transmission (freeze-etch) electron microscopy to characterize lens structure in normal mice and compare it with that in mice deficient in the major intrinsic protein (MIP) of fiber cells. Grossly, wild-type lenses were transparent and had typical Y sutures at all of the ages examined. These lenses had fibers of uniform shape (hexagonal in cross section) arranged in ordered concentric growth shells and radial cell columns. In addition, these fibers had normal opposite end curvature and lateral interdigitations regularly arrayed along their length. Ultrastructural evaluation of these fibers revealed anterior and posterior end segments characterized by square array membrane on low-amplitude wavy fiber membrane. Approximately 13% of the equatorial or mid segments of these same fibers were specialized as gap junctions (GJs). In contrast, heterozygote lenses, while initially transparent at birth, were translucent by 3 weeks of age, except for a peripheral transparent region that contained fibers in the early stages of elongation. This degradation in clarity was correlated with abnormal fiber structure. Specifically, although the mid segment of these fibers was essentially normal, their end segments lacked normal opposite end curvature, were larger than normal, and had a distinct non-hexagonal shape. As a result, these fibers failed to form typical Y sutures. Furthermore, the nuclear fibers of heterozygote lenses were even larger and lacked any semblance of an ordered packing arrangement. Grossly, homozygote lenses were opaque at all ages examined, except for a peripheral transparent region that contained fibers in the early stages of elongation. All fibers from homozygote lenses lacked opposite end curvature, and thus failed to form any sutures. Also, these fibers were essentially devoid of interlocking devices, and only 7% of their mid segment was specialized as GJs. The results of this study suggest that MIP has essential roles in the establishment and maintenance of uniform fiber structure, and the organization of fibers, and as such is essential for lens function. Anat Rec Part A 273A: 714 -730, 2003.

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“…21 Other methods to reduce postvitrectomy cataracts include a novel irrigation solution containing benzopyranyl esters and amides, which in a rabbit animal model prevented abnormal postvitrectomy posterior lens fiber changes. 22 Last, maintaining "face-down" positioning to reduce direct contact of the gas and the lens postsurgery has been shown to reduce postvitrectomy cataract formation after gas tamponade. 23 ' Challenges to Anterior Segment Surgeon…”

Section: Prevention Of Postvitrectomy Cataractsmentioning

confidence: 99%