Ophthalmol Clin North Am
· 2004 Jun · PMID 15207556
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Wavefront sensing represents a novel diagnostic method to measure high-order aberrations. This technology has primarily been used in conjunction with excimer laser technology for performing wavefront-guided custom ablati...Wavefront sensing represents a novel diagnostic method to measure high-order aberrations. This technology has primarily been used in conjunction with excimer laser technology for performing wavefront-guided custom ablations, targeted at the correction of low- and high-order aberrations, while not inducing further high-order aberrations.Although this field of application remains predominant, wavefront sensing may also be used successfully in the diagnosis and detection of vision problems, as reported by patients, related to the presence of high-order aberrations. Currently, wavefront analysis represents the only diagnostic tool clinically available to explore all of the refraction and diffraction problems generated by the presence of high-order aberrations.
Solomon KD, Fernández de Castro LE, Sandoval HP
… +1 more, Vroman DT
Ophthalmol Clin North Am
· 2004 Jun · PMID 15207555
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Wavefront measurement is an emerging technology that can evaluate low-order and high-order aberrations. This review compiles the different wavefront sensing devices and compares the most popular Hartmann-Shack aberromete...Wavefront measurement is an emerging technology that can evaluate low-order and high-order aberrations. This review compiles the different wavefront sensing devices and compares the most popular Hartmann-Shack aberrometers.
Ophthalmol Clin North Am
· 2004 Jun · PMID 15207554
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This article reviews the fundamental principles by which wavefront aberrometers measure ocular aberrations. Three different ways of interpreting aberration measurements are described in terms of wavefront phase, slope, a...This article reviews the fundamental principles by which wavefront aberrometers measure ocular aberrations. Three different ways of interpreting aberration measurements are described in terms of wavefront phase, slope, and curvature. Although curvature is the more familiar concept from geometrical optics, the wave optics concept of wavefront phase is more useful for understanding the nature of aberrated retinal images and for prescribing treatments to correct high-order aberrations.
Ophthalmol Clin North Am
· 2004 Mar · PMID 15102515
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Multifocal VEP and mfERG techniques show promise for routine clinical use in neuro-ophthalmology. OCT is now used in many subspecialty areas of ophthalmology, especially in studies of the retina and glaucoma. Although ne...Multifocal VEP and mfERG techniques show promise for routine clinical use in neuro-ophthalmology. OCT is now used in many subspecialty areas of ophthalmology, especially in studies of the retina and glaucoma. Although neuro-ophthalmologists must still rely on time-consuming history taking and careful clinical examination, the three modalities described herein can provide objective proof regarding clinical diagnoses in selected cases, saving time and avoiding costly neurologic investigations.
Ophthalmol Clin North Am
· 2004 Mar · PMID 15102514
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Multifocal VEP technology is still in its infancy. Although many aspects of the recording and analysis will be improved with time, the mfVEP can be used in the clinic today. It can help to identify functional (nonorganic...Multifocal VEP technology is still in its infancy. Although many aspects of the recording and analysis will be improved with time, the mfVEP can be used in the clinic today. It can help to identify functional (nonorganic) problems, demyelinating diseases, glaucomatous damage, and poor field takers. Given the software and techniques needed to record and interpret the results, mfVEP testing should be performed in centers experienced with this technique.
Grinvald A, Bonhoeffer T, Vanzetta I
… +4 more, Pollack A, Aloni E, Ofri R, Nelson D
Ophthalmol Clin North Am
· 2004 Mar · PMID 15102513
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Much work remains to be done to establish the clinical usefulness of the RFI for early diagnosis and treatment guidance. The discoveries obtained by functional optical imaging of the neocortex in the last 15 years and th...Much work remains to be done to establish the clinical usefulness of the RFI for early diagnosis and treatment guidance. The discoveries obtained by functional optical imaging of the neocortex in the last 15 years and the recent RFI studies of the eyes of normal subjects and patients with diabetic retinopathy, glaucoma, and age-related macular degeneration suggest that functional optical imaging of the retina is likely to become a multi-modality powerful clinical tool.
Ophthalmol Clin North Am
· 2004 Mar · PMID 15102512
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Structural assessment using the imaging technologies discussed herein provides reproducible quantitative measurements of posterior segment ocular structures. These measurements have been found to provide useful data for...Structural assessment using the imaging technologies discussed herein provides reproducible quantitative measurements of posterior segment ocular structures. These measurements have been found to provide useful data for glaucoma detection in various regions of the posterior segment. Further studies are needed to evaluate the utility of these technologies for pre-perimetric glaucoma detection and for monitoring glaucoma progression over an extended period.
Ophthalmol Clin North Am
· 2004 Mar · PMID 15102511
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Optical coherence tomography provides high-resolution cross-sectional images of macular pathology in vivo. Owing to its noninvasive noncontact nature and use of near-infrared illumination of the fundus, it is well tolera...Optical coherence tomography provides high-resolution cross-sectional images of macular pathology in vivo. Owing to its noninvasive noncontact nature and use of near-infrared illumination of the fundus, it is well tolerated by patients. The images can be obtained without dilation and are highly reproducible,quantifying retinal thickness with an axial resolution of 10 microm. These qualities make OCT a powerful diagnostic tool complementary to fluorescein angiography, photography, and biomicroscopy. Optical coherence tomography has proved to be particularly useful for the clinical evaluation of vitreoretinal interface disorders and alterations of the structural anatomy of the macula, such as from edema, choroidal neovascularization, and detachment of the neurosensory retina or RPE. The information obtained from high-resolution evaluation of retinal anatomy allows the diagnosis of conditions that are difficult to establish with biomicroscopy or angiography and improves the clinician's ability to make the optimal treatment decision. The quantitative assessment of OCT allows an objective means to monitor disease progression and therapeutic response.A logical application of this technology is the evaluation of underlying macular pathology in patients considering cataract extraction. Uncovering vitreomacular traction, epiretinal membranes, occult choroidal neovascular membranes with minimal CME, subretinal fluid accumulation, and RPE detachments greatly impacts the clinical management of cataract patients and the weighing of surgical risks and benefits. OCT is a uniquely powerful means of visualizing retinal morphology and pathology that may not be revealed using current techniques of biomicroscopy, fluorescein angiography, or B-scan ultrasonography, and serves as the newest adjunct in diagnostic technology.
Ophthalmol Clin North Am
· 2004 Mar · PMID 15102510
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Ultrasound biomicroscopy technology has become an indispensable tool in qualitative and quantitative assessment of the anterior segment. Advances in soft-ware design and algorithms will improve theoretical understanding...Ultrasound biomicroscopy technology has become an indispensable tool in qualitative and quantitative assessment of the anterior segment. Advances in soft-ware design and algorithms will improve theoretical understanding of the pathophysiology of anterior segment disorders. Future applications of quantitative techniques will yield important information regarding mechanisms of angle closure, improving understanding of the dynamic functions of the iris,accommodation, presbyopia, and other aspects of anterior segment physiology and pathophysiology.
Ophthalmol Clin North Am
· 2004 Mar · PMID 15102509
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Optical coherence tomography is a versatile tool for visualization and measurement of corneal and anterior segment anatomy. Keratorefractive surgery, anterior chamber biometry, and angle assessment are some of the applic...Optical coherence tomography is a versatile tool for visualization and measurement of corneal and anterior segment anatomy. Keratorefractive surgery, anterior chamber biometry, and angle assessment are some of the applications that should benefit from this technology.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14741004
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As new genes and common mutations are identified, DNA testing can be offered. Like clinical testing used in glaucoma, such as IOP, tonography, disc measurements, nerve fiber layer analysis, and the various methods of vis...As new genes and common mutations are identified, DNA testing can be offered. Like clinical testing used in glaucoma, such as IOP, tonography, disc measurements, nerve fiber layer analysis, and the various methods of visual field analysis, well-designed studies are needed to be able to interpret clearly the meaning of abnormal results. To use DNA testing to identify individuals at high risk for glaucoma, it is necessary to have solid evidence with sensitivity and specificity parameters, genotype-phenotype correlations, and information on prevalence and penetrance. These data will have to be replicated in several studies using large, population-matched control groups. Mass screening of glaucoma patients for Myocilin mutations may be worthwhile if 3% to 5% of glaucoma patients will be positive. For comparison, screening all cases of colon cancer for gene mutations involved in hereditary nonpolyposis colorectal cancer is considered feasible and desirable with a yield of only 3%. Recent research has shown the value of early treatment of glaucoma. The cost effectiveness of genetics screening will need to be weighed against the cost of conventional screening and the benefits of early treatment considered. Within glaucoma pedigrees with known mutations, DNA mutation-positive individuals will need more frequent clinical screening, whereas DNA mutation-negative individuals will need less frequent follow-up. It is likely that, for every positive-mutation glaucoma case identified, there will be on average two siblings and two children to test. In addition to the laboratory costs, the costs of counseling, and, in particular, the availability of suitably trained individuals who can correctly interpret these test results, must be considered. The risk and benefits of these measures must be calculated and then balanced with the long-term visual outcome of such a strategy. How could genetic testing alter management in glaucoma? If a family member in a Myocilin pedigree with a severe mutation is negative for the mutation, that individual's risk changes from 50% to that of the general population (ie, -2%), and the frequency of clinical screening can be reduced. There are ethical issues involved in testing, particularly in children, but testing would seem justified in congenital, developmental, and juvenile glaucoma. Issues related to insurance may affect the decision making of some patients. A further consideration, which may regrettably become important in the future, is that of intellectual property and patent issues pertaining to glaucoma gene discovery. In addition to clinical evidence of the value of predictive DNA testing, it is incumbent on those working in the field to evaluate the acceptability of testing to patients and their family members. The authors' experience to date is that predictive DNA testing in glaucoma is well supported in suitable families. As with predictive DNA screening in other ophthalmic conditions, issues relating to insurance, ethics, and confidentiality need to be taken into consideration. Although many of the more recently described genetic associations of POAG require more thorough evaluation, Myocilin gene testing can and should be offered for young-onset severe glaucoma cases with a positive family history.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14741003
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POAG is a severely debilitating disease in West Africa. Currently, many patients seem to be misclassified as having POAG who in fact have CACG. Improved examination techniques, including routine gonioscopy, would increas...POAG is a severely debilitating disease in West Africa. Currently, many patients seem to be misclassified as having POAG who in fact have CACG. Improved examination techniques, including routine gonioscopy, would increase diagnostic accuracy and improve treatment strategies. The incidence of Myocilin mutations in this group of individuals is similar to that found in other populations around the world. Myocilin plays a limited role in the pathogenesis of POAG in this population.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14741002
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Retinoblastoma as a genetic disease is a paradigm for tumor-suppressor gene theory. The RB gene is one of the best-studied tumor-suppressor genes with known key functions in controlling cell proliferation and differentia...Retinoblastoma as a genetic disease is a paradigm for tumor-suppressor gene theory. The RB gene is one of the best-studied tumor-suppressor genes with known key functions in controlling cell proliferation and differentiation. Reconstitution of RB function in RB-deficient tumor cells induces irreversible growth arrest (senescence) and inhibits telomerase activity, simultaneously correcting two of the four defined carcinogenic events in human cells. RB gene therapy has the advantage of selectively killing tumor cells without adverse side effects to normal somatic cells, and efficacy of the therapy has now been demonstrated in vitro and in immunocompetent mouse models. Most preclinical studies of RB gene therapy reported to date have used RB fragments with enhanced cell growth-suppressing function. The clinical success of RB gene therapy of retinoblastoma, however, requires more innovation in vector development.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14741001
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Isolated keratoconus with no associations is by far the most common keratoconus presentation seen by a practicing clinician. This article explores the genetics of this most common form of keratoconus.Isolated keratoconus with no associations is by far the most common keratoconus presentation seen by a practicing clinician. This article explores the genetics of this most common form of keratoconus.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14741000
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This article provides an overview of the genetic aspects of neuro-ophthalmic disorders. Leber's hereditary optic neuropathy, optic nerve hypoplasia, Duane's retraction syndrome, congenital nystagmus, and other disorders...This article provides an overview of the genetic aspects of neuro-ophthalmic disorders. Leber's hereditary optic neuropathy, optic nerve hypoplasia, Duane's retraction syndrome, congenital nystagmus, and other disorders of neuro-ophthalmic interest are discussed.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14740999
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Inherited retinal and choroidal degenerations account for a significant portion of blindness in children and young adults. This article reviews the current status and future prospects for the treatment of these disorders...Inherited retinal and choroidal degenerations account for a significant portion of blindness in children and young adults. This article reviews the current status and future prospects for the treatment of these disorders. Current treatment strategies include nutritional intervention for gyrate atrophy of the choroid and retina with hyperornithinemia, abetalipoproteinemia, and Refsum's disease, as well as vitamin A supplementation for retinitis pigmentosa. Future therapeutic prospects include gene therapy for both recessive and dominant disease, secondary gene-based therapies, such as pharmaceutic gene product replacement and treatment with survival factors, anti-apoptotic agents, and calcium blockers, and, finally, stem cell therapy.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14740998
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The technology of gene therapy may be one step ahead of the present understanding of angiogenesis. The results of studies to modulate angiogenesis have been encouraging, however, and several of these studies are in the p...The technology of gene therapy may be one step ahead of the present understanding of angiogenesis. The results of studies to modulate angiogenesis have been encouraging, however, and several of these studies are in the preclinical and clinical phases of testing. It is likely, therefore, that gene therapy for such diseases as diabetes mellitus and age-related macular degeneration will soon become a practical reality. It must be hoped that the lessons learned will be beneficial to others attempting to modulate angiogenesis in systemic disorders such as cancer and rheumatoid arthritis.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14740997
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Gene discoveries will lead to more effective them pies for AMD by identifying specific underlying disease mechanisms that might be corrected by drugs or gene therapy. For example, investigations are currently being carri...Gene discoveries will lead to more effective them pies for AMD by identifying specific underlying disease mechanisms that might be corrected by drugs or gene therapy. For example, investigations are currently being carried out using pigment epithelium-derived factor (FEDF). The gene for this potent inhibitor of angiogenesis has been incorporated into an adenoviral vector and delivered into the eye by intravitreal injection to inhibit growth of new blood vessels in eyes with neovascular AMD. In the future, as the genetics of this complex disease are unraveled, more effective treatments and preventative measures that target specific molecular defects underlying the development of AMD can be expected.
Ophthalmol Clin North Am
· 2003 Dec · PMID 14740996
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Uveitis phenotypes can differ substantially, and most uveitis diseases are considered polygenic with complex inheritance patterns. When considering the genetics of these diseases, common threads can be identified. For ex...Uveitis phenotypes can differ substantially, and most uveitis diseases are considered polygenic with complex inheritance patterns. When considering the genetics of these diseases, common threads can be identified. For example, in virtually every polygenic disease studied, there exists an HLA genetic association. This association can be strong, such as the associations of HLA-B27 with AAU and HLA-A29 with BSCR; or it can be more subtle, involving several HLA genes or a combination of HLA genes that compose specific haplotypes. In many of these conditions, it is hypothesized that genes other than classic MHC genes but located at the MHC locus may be important susceptibility genes. Genome-wide scans and other genetic methods are becoming increasingly successful in identifying genetic loci and candidate genes in many inflammatory disorders that have an uveitic component. It will be important to test these findings as uveitis-specific genetic factors. Therefore, the burgeoning understanding of the human genome promises to result in new insight into the pathogenesis of uveitis.