Ophthalmol Clin North Am
· 2003 Dec · PMID 14740995
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Several observations noted by early investigators supported the supposition that in most cases, congenital glaucoma is determined by genetic factors. The genetic heterogeneity of PCG was confirmed by genetic linkage stud...Several observations noted by early investigators supported the supposition that in most cases, congenital glaucoma is determined by genetic factors. The genetic heterogeneity of PCG was confirmed by genetic linkage studies conducted in the 1990s when the authors determined that CYP1B1 is the congenital glaucoma gene at the GLC3A locus. The coding sequence of CYP1B1 has been subjected to extensive screening in familial and sporadic cases of glaucoma from numerous countries and from a large number of ethnic groups. These studies have provided evidence for extensive allelic heterogeneity at the GLC3A locus. This article also discusses the molecular evidence for reduced penetrance in congenital glaucoma and the phenotypic heterogeneity of CYP1B1 mutations, mouse models of CYP1B1, and the biochemistry of CYP1B1.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14740994
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The authors' initial estimate indicated that mutations in Optineurin are responsible for a significant proportion of LPG/POAG families. Currently, there are up to 1.2 million persons with LPG and up to 2.47 million perso...The authors' initial estimate indicated that mutations in Optineurin are responsible for a significant proportion of LPG/POAG families. Currently, there are up to 1.2 million persons with LPG and up to 2.47 million persons with POAG in the United States alone. Perhaps twice as many individuals are already affected with this condition without any identifiable clinical signs or symptoms. Investigators are eagerly awaiting confirmation of OPTN mutations in other glaucoma populations. Although additional mutations have already been identified in the sporadic cases of LPG, the significance of this gene in high-pressure POAG requires more intensive investigation. Limited data on partial screening of this gene indicate that OPTN mutations are responsible for a limited number of cases of high-pressure POAG. If the reported mutation rates of OPTN in the LPG group can be confirmed in other LPG or POAG patients, then this gene would be useful in diagnosing presymptomatic persons many decades before they develop this silent and blinding eye condition. Early identification of such at-risk patients would provide an opportunity for immediate targeted medical treatments and specific glaucoma therapy that might significantly delay or completely stop the gradual progression of this condition. Therefore, identification of glaucoma-causing genes such as Myocilin, Optineurin, and others could provide molecular diagnostic tools for this category of optic neuropathy. Although patients with advanced glaucoma will not directly benefit from the use of such molecular diagnostic tools, their immediate family members could certainly benefit from the identification of the cause of the glaucoma decades before the first manifestation of the disease. In summary, a series of mutations in the Optineurin gene have been shown to be the principal cause of adult-onset LPG/POAG phenotype in certain pedigrees. The exact mechanisms through which these mutations lead to the development of glaucoma require additional functional study. The existing evidence suggests that direct interaction of Optineurin with E3-14.7K protein probably utilizes TNF-alpha or Fas-ligand pathways to mediate apoptosis, inflammation, or vasoconstriction. Optineurin also functions through its interactions with other proteins in cellular morphogenesis and membrane trafficking (RAB8), vesicle trafficking (Huntingtin), transcription activation (TFIIIA), and assembly or activity of two unknown kinases. Identification of Optineurin as an adult-onset glaucoma gene and its known interaction with a group of proteins provides the first opportunity to study biochemical pathways that are thought to be involved in causation of this group of eye disorders. Furthermore, identification of this gene as a contributing factor to the development of glaucoma gives a useful tool for screening of this disorder in the elderly population and other high-risk individuals. The exact impact of OPTN in the development of all glaucoma phenotypes requires future study.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14740993
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Over the past several years, many groups worldwide have confirmed the presence of probable disease-causing mutations in the coding region of the (TIGR/MYOC) gene associated with glaucoma. Disease-associated point mutatio...Over the past several years, many groups worldwide have confirmed the presence of probable disease-causing mutations in the coding region of the (TIGR/MYOC) gene associated with glaucoma. Disease-associated point mutations are often found in the third exon of TIGR/MYOC and are predicted to exert a substantial influence on protein structure. Although there has been speculation as to the mechanisms involved in the pathogenic effects for a number of the mutations, the processes leading to the development of glaucoma involving TIGR/MYOC remain to be elucidated. In addition to ongoing mutation studies, efforts are underway to follow up on TIGR/MYOC gene regulation studies in human trabecular meshwork cells and other possibly relevant cell types. Potentially by altering gene regulation, a major variant (-1000 G/C), present in 15-20% of individuals, appears to be associated with a more rapid progression of glaucomatous disease. This article addresses several of these areas of research on the TIGR/MYOC gene and glaucoma, briefly presenting currently available evidence and considering or updating information presented previously.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14740992
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As Posner stated in 1949, the bottom line "to the patient and to his family is..., whether his disease will follow a mild course or will lead to blindness". The final goal of genetic research is the identification of the...As Posner stated in 1949, the bottom line "to the patient and to his family is..., whether his disease will follow a mild course or will lead to blindness". The final goal of genetic research is the identification of the causal genes in the patient, to aid the ophthalmologist in predicting the outcome, in determining diligent treatment is required, and ultimately, in providing the tools for preventing blindness.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14740991
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Rapid progress is occurring in molecular cell biology and genetics in the understanding of basic cellular mechanisms and the potential for genetic therapy. As new methods of genetic prognosis and treatment become availab...Rapid progress is occurring in molecular cell biology and genetics in the understanding of basic cellular mechanisms and the potential for genetic therapy. As new methods of genetic prognosis and treatment become available, and diseases are redefined in genetic terms, it is essential that clinicians know more about genetic therapy. This article provides a basic outline of gene therapy.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564769
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This article addresses the spectrum of corneal infections associated with contact lens wear. The status of bacterial, fungal, and Acanthamoeba keratitis is discussed as well as diagnosis and treatment for these infection...This article addresses the spectrum of corneal infections associated with contact lens wear. The status of bacterial, fungal, and Acanthamoeba keratitis is discussed as well as diagnosis and treatment for these infections.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564768
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Complications associated with contact lenses range from mild to severe and occur with all lens modalities. Contact lens wear can cause a change in corneal physiology, which can lead to epithelial, stromal, and endothelia...Complications associated with contact lenses range from mild to severe and occur with all lens modalities. Contact lens wear can cause a change in corneal physiology, which can lead to epithelial, stromal, and endothelial compromise. Other complications include lens deposition, allergic conjunctivitis, giant papillary conjunctivitis, peripheral infiltrates, microbial keratitis, and neovascularization. Pre-existing conditions can contribute to these complications, or they can occur in association with contact lens wear and care regimens. Patient-related factors, such as alteration of the recommended wearing or replacement schedules and noncompliance with recommended contact lens care regimens for economic reasons, convenience, or in error, contribute to contact lens-related complications and have led to difficulty in accurate determination of complication rates among the various lens wear modalities. Complications may require discontinuation of contact lenses, topical therapy, and changes in contact lens wearing schedules, materials, and care solutions. On initial lens fitting and follow-up evaluations, practitioners should review contact lens replacement and cleaning regimens with patients and discuss complications. To avoid serious complications, patients should be reminded to remove their contact lenses as soon as ocular irritation occurs, and to call their eye care practitioner immediately if symptoms persist.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564767
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Contact lenses should be used with caution in patients who have an ocular allergy. Patients who have seasonal allergy should avoid contact lens use during seasonal flare-ups. The need for clean lenses with minimal deposi...Contact lenses should be used with caution in patients who have an ocular allergy. Patients who have seasonal allergy should avoid contact lens use during seasonal flare-ups. The need for clean lenses with minimal deposit buildup must be stressed, and the use of daily wear lenses with rigid disinfecting and cleaning techniques is recommended. Alternatively, daily disposable lenses should be used. The patient should avoid the use of topical anti-allergy agents while the lenses are in place, particularly vasoconstrictor agents. Extended wear contact lenses are contraindicated in patients who have ocular allergy. In general, the use of contact lenses is contraindicated in patients with vernal conjunctivitis. With careful attention to recognizing the patient with ocular allergy, regular monitoring, and patient compliance to lens care, successful contact lens wear can be achieved in most patients with ocular allergy.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564766
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Currently, the armamentarium of contact lenses that can be used for therapeutic effect provides a wider selection of lenses than ever before. If the therapeutic goal is protection and healing of the corneal epithelium, e...Currently, the armamentarium of contact lenses that can be used for therapeutic effect provides a wider selection of lenses than ever before. If the therapeutic goal is protection and healing of the corneal epithelium, epithelial or stromal edema is best avoided, and the selection of a high-Dk silicone hydrogel (balafilcon A, lotrafilcon A) lens or a very thin membrane-type lens (crofilcon) is the best choice. If the goal is surface protection as well as stimulation of stromal wound vascularization, selection of a low-water content, thick, hydrophilic lens is the better option. If the patient is prone to lens loss or requires frequent replacement of the therapeutic lens, a prudent economic decision is to select a daily disposable moderate-water content lens. Specific circumstances may mandate the selection of a specific therapeutic lens. Patients with a prior history of active giant papillary conjunctivitis may be better served by the use of a crofilcon glyceryl methacrylate lens, which has a lower incidence of this complication. Patients who have dry eye may benefit from a higher-water content lens if adequate unpreserved tear supplementation is provided with or without punctal occlusion. The options when selecting a therapeutic contact lens are wider than ever before. Although the new generation of high-Dk lenses promises fewer limiting problems of vascularization and infection, one can use the older traditional therapeutic lenses when induced vascularization of the cornea is needed or when an economic necessity exists. Not all of the available lenses are FDA approved for therapeutic use, and such wear is an off-label use. The patient should be informed of the goal of therapy as well as the benefits and risks of therapeutic contact lenses.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564765
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Regardless of whether CVK is used qualitatively for RGP lens design selection or quantitatively in RGP parameter selection, it has a significant role in contact lens practice. Further advancements and testing on CVK-base...Regardless of whether CVK is used qualitatively for RGP lens design selection or quantitatively in RGP parameter selection, it has a significant role in contact lens practice. Further advancements and testing on CVK-based RGP fitting modules and fluorescein simulations will make CVK an invaluable tool for the RGP lens fitter. Soft lens applications of CVK data are already being tested [42,43]. This technology will become the standard of care for all contact lens patients and will most likely replace the keratometer.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564764
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Contact lens care has been revolutionized and simplified with the development of multipurpose solutions, less sensitizing preservatives and disinfectants, better protein removers, and reaction-free, one-bottle care syste...Contact lens care has been revolutionized and simplified with the development of multipurpose solutions, less sensitizing preservatives and disinfectants, better protein removers, and reaction-free, one-bottle care systems for patients who have had adverse responses to existing care products. As the complexity of lens care has decreased, compliance has increased. Nevertheless, good compliance is dependent on technician training and a thorough understanding of the chemistry and mechanism of action of each care system. Care products are constantly evolving, and the practitioner should become familiar with each new solution as it is introduced to ensure that patients are also kept up-to-date.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564763
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The renaissance of corneal reshaping has been influenced dramatically by new lens designs, high-oxygen permeable materials, and corneal mapping techniques. These evolutionary advances have dramatically changed the practi...The renaissance of corneal reshaping has been influenced dramatically by new lens designs, high-oxygen permeable materials, and corneal mapping techniques. These evolutionary advances have dramatically changed the practitioner's view of the modality. The procedure has evolved from a specialty practiced by only a handful of practitioners to a technique that can be incorporated successfully into almost any eye care practice.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564762
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Corneal refractive surgery has enjoyed considerable success and popularity in recent years; LASIK has become the surgical procedure of choice. The incidence of visually significant complications varies widely, but is inv...Corneal refractive surgery has enjoyed considerable success and popularity in recent years; LASIK has become the surgical procedure of choice. The incidence of visually significant complications varies widely, but is inversely related to surgeon experience. Visual complaints include multifocal images, shadows, ametropias, anisometropia, night vision difficulties, decreased contrast sensitivity and loss of BCVA. Contact lenses offer an option to rehabilitate patients when visually symptomatic following refractive surgery. RGP lenses provide the best postoperative visual rehabilitation following refractive surgery.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564761
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This article describes use of contact lenses to manage patients with keratoconus. Fitting concepts, prefit evaluations, types of lenses, initial lens selection, and potential problems and solutions are discussed.This article describes use of contact lenses to manage patients with keratoconus. Fitting concepts, prefit evaluations, types of lenses, initial lens selection, and potential problems and solutions are discussed.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564760
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According to Paragon Vision Sciences (Mesa, AZ), an additional 50,000 Americans become presbyopic each day. There are many contact lens options available to help these patients meet their visual needs in the workplace an...According to Paragon Vision Sciences (Mesa, AZ), an additional 50,000 Americans become presbyopic each day. There are many contact lens options available to help these patients meet their visual needs in the workplace and for recreational and social activities. Although technology still requires some compromise on the part of many patients, constant advances in materials and designs should enable even greater numbers of presbyopes to enjoy the freedom of functioning without glasses in the years to come.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564759
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Comparison of the results of keratometry and refraction usually suggests the appropriate contact lens for a patient's eye. Specialized rigid toric contact lenses include bitoric and back toric RGP lenses, front toric RGP...Comparison of the results of keratometry and refraction usually suggests the appropriate contact lens for a patient's eye. Specialized rigid toric contact lenses include bitoric and back toric RGP lenses, front toric RGP lenses, and bitoric RGP lenses with prism ballast. Each lens has specific indications.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564758
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Soft contact lens correction for astigmatism has made significant advances over the last 20 years. Soft toric tinted lenses, disposables lenses, and bifocal lenses are now available at lower costs with greater reproducib...Soft contact lens correction for astigmatism has made significant advances over the last 20 years. Soft toric tinted lenses, disposables lenses, and bifocal lenses are now available at lower costs with greater reproducibility, enhanced parameters, and better comfort. Because of these innovations and significant design changes, a greater percentage of astigmatic patients are being treated with soft toric lenses than before.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564757
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Disposable and frequent replacement contact lenses dominate the marketplace. They are available in a wide variety of parameters for use in refractive errors, including myopia, hyperopia, astigmatism, and presbyopia. They...Disposable and frequent replacement contact lenses dominate the marketplace. They are available in a wide variety of parameters for use in refractive errors, including myopia, hyperopia, astigmatism, and presbyopia. They are convenient and affordable and lend themselves to most wearing modalities, including daily wear, flexible wear, and extended wear for up to 30 days. In addition, they have been shown to be the most trouble-free contact lens wear modality for daily wear or extended wear. They are an appropriate choice for patients who desire occasional contact lens wear and have gained wide acceptance as therapeutic bandage contact lenses. Disposable and frequent replacement lenses will remain important modalities for some time to come as the variety of contact lenses and contact lens parameters that are offered continue to expand. New contact lens varieties, such as the high-Dk silicone hydrogel lenses, will further expand the role of these contact lenses in vision correction.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564756
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Contact lenses made from materials of low-oxygen permeability (Dk) do not meet the oxygen requirements of the cornea for overnight wear. Long-term extended wear of these lenses results in chronic changes to all layers of...Contact lenses made from materials of low-oxygen permeability (Dk) do not meet the oxygen requirements of the cornea for overnight wear. Long-term extended wear of these lenses results in chronic changes to all layers of the cornea, many of which are associated with hypoxia. High-Dk silicone hydrogel and gas permeable lenses are now available for 30-night continuous wear. The high-oxygen transmissibilities of these lenses have enabled the development of a successful continuous wear modality by eliminating the hypoxic effects of long-term wear. Presently, the focus is on improving lens performance by developing lenses that are more biocompatible, provide greater comfort, and maintain a stable tear film without inflammatory or mechanically induced adverse events.
Ophthalmol Clin North Am
· 2003 Sep · PMID 14564755
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Contact lens were and eyelid suturing diminish overall Bcl-2 expression in the corneal epithelium, yet nuclear Bcl-2 in the exposed surface epithelial cells seems to be retained for longer periods when compared with the...Contact lens were and eyelid suturing diminish overall Bcl-2 expression in the corneal epithelium, yet nuclear Bcl-2 in the exposed surface epithelial cells seems to be retained for longer periods when compared with the retention in control eyes. This observation may explain why there is a decrease in surface cell exfoliation during CTL wear, because nuclear Bcl-2 loss needs to precede apoptotic surface cell exfoliation. In addition, if the hypothesis is true that Bcl-2 also has a regulatory function in the proliferation and differentiation of tissues, the overall reduced expression of Bcl-2 (nuclear plus cytoplasmic) may clarify the decrease in proliferation of the corneal epithelium seen during CTL wear. Future studies should clarify the role of Bcl-2 in the homeostatic dynamics of the corneal epithelium. CTL wear and eyelid suturing provide excellent noninflammatory models to advance knowledge of Bcl-2 and its regulatory roles. Additionally, these models should help researchers gain a better understanding of the CTL-associated effects on corneal epithelium.