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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cooperative Cataract Research Group (CCRG) photographic procedures developed by Chylack have made it possible to localize and analyze specific lens opacities for their ultrastructural and chemical characteristics. One group of human lens opacities has been shown to have a high phosphorus/sulfur ratio (as compared to normal lens fiber cells) and an accumulation of unit membranes. The present paper describes another variety of human lens opacity with the following characteristics: (1) high calcium, low sulfur, undetectable phosphorus, as determined by Energy Dispersive X-ray Analysis (EDXA) of bulk specimens in the scanning electron microscope (SEM), or "thick" sections with the transmission mode of the SEM; (2) spheroidal shape; (3) up to approximately 300 microns in size; and (4) birefringence. Microchemical analysis of these opacities shows that the calcium is in the form of calcium oxalate. These calcium-containing opacities, which have been detected in 14 out of 406 human cataractous lenses, have a characteristic morphology, as seen in the CCRG stereo photographs. Therefore, the presence of these calcium opacities, if not obscured by other kinds of opacities, can be detected with a high degree of accuracy in the fresh lens from the CCRG photographs alone.
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PMID:Calcium-containing opacities in the human lens. 688 7

In 1891, Priestly Smith wrote that in glaucoma surgery, "the lens is occasionally wounded, unsuspected by the operator," and described serious consequences. In 1953 Christensen and McLean found histologic evidence of perforation of the lens capsule in many eyes which had been enucleated after unsuccessful glaucoma surgery. Twelve additional enucleated eyes with lens perforations plus clinical consultations indicate that unintentional surgical injuries to the lens still are occurring during iridectomies, filtrations, and trabeculectomies and usually are unsuspected by the surgeon. This injury should be considered when a lens opacity becomes manifest within a few days or weeks after surgery. In addition to failure of the operation, the consequences vary from limited cataract formation to complete opacification and subluxation of the lens. The lens injury also may cause a severe phacogenic uveitis which requires early lens extraction to avoid extensive intraocular fibroplasia. Clinical features and histopathology are presented with illustrative cases. The prevention and management of unintentional lens injury are discussed.
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PMID:Unintentional lens injury in glaucoma surgery. 697 30

Cataracts, inherited in an autosomal dominant manner in New Zealand Romney sheep were first detected at 1 - 2 months of age as focal anterior and posterior cortical opacities. Within a short time these coalesced to form spoke-like patterns which gradually became more diffuse. Total lens opacity developed by 10 - 11 months of age. Congenital mature cataracts occurred in two lambs believed to be homozygous for the mutant gene and in these animals lens resorption later occurred. Histology showed that new lens fibres formed normally at the equator but then underwent progressive degenerative swelling and lysis. Cytoplasmic vacuolation of anterior epithelial cells was a notable feature and occurred apparently in response to adjacent cortical degeneration. Ultrastructurally these vacuoles were interpreted as dilations of endoplasmic reticulum but there were also a number of smaller vacuoles not lined by membrane. Anterior epithelial cells also underwent metaplasia, hyperplasia, and migration beneath the posterior capsule. Analyses of lenses reflecting different stages of cataractogenesis showed a progressive increase in water, sodium and calcium ions with cataract development and a concomitant decrease in potassium and magnesium ions.
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PMID:The pathology of an inherited cataract of sheep. 718 16

Cataracts were found in four patients with pathologically confirmed Zellweger syndrome. By careful slitlamp examination with the pupil completely dilated, there is a denser cortex that produces a cortical-nuclear interface. These opacities have ultrastructural analogues, which are inclusion bodies restricted to the cortical lens fibers. The lens epithelium shows abnormal mitochondrial proliferation that is age dependent. The parents of these four infants with Zellweger syndrome have lenticular opacities that are seen only biomicroscopically after maximal pupillary dilation. These changes consist of curvilinear condensations in the cortical region corresponding to the locus of the cataractous changes in the homozygous state. In the clinical setting of an infant who is failing to thrive, has the Zellweger facies, and demonstrates an absent electroretinogram, these heterozygote lens opacities are useful in making the diagnosis of Zellweger syndrome before pathologic substantiation.
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PMID:Zellweger syndrome. Lenticular opacities indicating carrier status and lens abnormalities characteristic of homozygotes. 729 45

The Emory mouse cataract is a late-appearing lens opacity which may serve as an animal model for some human senile cataracts. It is inherited as an autosomal dominant trait and has a typical course of development. Lens opacities may become readily apparent as early as 6-8 months in mice having a familial history of early cataracto-genesis. Many gross morphologic and microscopic features resemble findings in human senile cataract. As an animal model it has many desirable characteristics. Its slow development permits studies of the lens at the pre-cataractous stage and makes it a good assay system for drugs or other factors affecting cataractogenesis. In this paper are given some morphologic and histologic aspects of the developing cataract.
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PMID:The Emory mouse cataract: an animal model for human senile cataract. 734 36

A longitudinal biomicroscopic study of lenses and fundi of over 2,000 Peromyscus maniculatus (deer mice) which have cataracts as an autosomal recessive trait has been correlated with histologic development of cataracts. By selective breeding, early-onset cataracts (Type I), which are frequently associated with abnormal closure of the fetal fissure and hyaloid vascular abnormalities, have been separated from later-onset (Type II) cataracts, which are more heterogeneous. Type I cataracts occur in syndactylous deer mice, develop rapidly, and histologically may show backward migration of disrupted lens bow cells before lens opacity is apparent biomicroscopically. Posterior subcapsular cataracts then develop and spread centrally and inferonasally to the equatorial area and then to the entire equator. The nucleus opacifies in either a "shell" pattern or as isolated dots. Anterior cortical opacification progresses to mature cataract. Histologically, abnormal migration and proliferation of lens epithelium and enlargement and vacuolar degeneration of the basal (posterior) process of cortical lens fibers are early changes in Type I cataracts. Disruption of the lens bow with failure of differentiation and inward turning of lens epithelium to become lens fibers occurs concurrently. Type II cataracts may follow the developmental pattern of Type I but are rarely associated with severe hyaloid vascular abnormalities and progress more slowly. About 6% of animals develop diabetes, which is not associated with the cataract-webbed trait.
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PMID:Cataract-webbed trait in Peromyscus. II. Biomicroscopy and histology of eyes. 735 Jan 32

This prospective study assessed visual results and subjective rehabilitation after cataract surgery in eyes with a preoperative acuity of 0.4 (20/40) or better. Fifty eyes (50 patients) were entered in the study. Corrected and uncorrected visual acuity, lens opacity, glare disability, and contrast sensitivity were measured before surgery and four months after surgery. Patient satisfaction was also measured. Best corrected visual acuity was 0.54 +/- 0.12 before surgery and 0.95 +/- 0.15 four months after surgery. Uncorrected visual acuity was 0.24 +/- 0.18 before and 0.58 +/- 0.27 after surgery. Impairment of corrected visual acuity from glare decreased from 0.12 +/- 0.09 before surgery to 0.04 +/- 0.08 four months after surgery. Contrast sensitivity at 6 cycles/degree increased from 2.71 +/- 0.94 units to 4.73 +/- 1.09 units. After surgery, 62% of patients judged their vision to be greatly improved, 32% judged it improved, 6% judged it unchanged. The patient's satisfaction was partially related to the improvement in uncorrected visual acuity. We conclude that cataract surgery can benefit eyes with limited visual impairment if the surgery is uncomplicated and IOL power is calculated correctly.
J Cataract Refract Surg 1995 Sep
PMID:Cataract surgery in eyes with early cataracts. 747 13

The use of polarised light in biomicroscopy allows discrimination of lenticular features which are not discernible using standard biomicroscopic techniques. However, just as is true of most brightness-dependent photographic methods testing the effect of filters, past uses of polarised light did not involve any control of illumination. The present study involved the use of polarised light in the photo-biomicroscopy of the anterior segment in cataract patients, the consequential loss in illumination being mimicked with different neutral density filters. This served to distinguish between polarisation and attentuation. The patients were refracted and their corrected visual acuity was recorded. A qualitative scale was drawn up ranking weights of lenticular opacities. Spearman's rank correlation was applied to the photographs obtained with conventional and polarised-light biomicroscopy in turn. Brightness control served to confirm that biomicroscopy with polarised light offers some advantages over conventional methods, and correlates with visual acuity better than is true of conventional biomicroscopy. The Spearman ranks derived from the results obtained with polarised light correlate significantly with the patient's visual acuity. It is concluded that polarised light biomicroscopy, in conjunction with the standard examination, can improve the diagnosis of cataract and assist in relating it to a patient's visual acuity.
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PMID:Polarising light biomicroscopy and the relation between visual acuity and cataract. 755 37

We used the Lens Opacities Classification System II to clinically grade the lenses of 57 patients with age-related cataracts in at least one eye. Progression or regression in each lens region was defined as a one or more step change in the Lens Opacities Classification System II grading noted at 1 year and maintained at the 1 1/2 to 2 year visit (the validation visit). A validated change in a lens region in one eye of a patient was considered a change in that region for that patient. Person-specific rates of cataract progression at 1 year were 42% for nuclear, 32% for cortical and 10% for posterior subcapsular opacities. Corresponding regression rates were 5%, 4%, and 2% for nuclear, cortical and posterior subcapsular opacities, respectively. Progression rates were significantly greater than the regression rates only for nuclear and cortical opacities (p < 0.0005). These findings show the applicability of the clinical Lens Opacities Classification System II method in documenting and monitoring lens changes over time. The usefulness of person-specific analysis was also shown.
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PMID:Progression of lens opacities in cataract patients after one year. 762 58

We compared pre- and postoperative visual acuities in 45 cataract patients without ocular pathology except lens opacity (group 1) and 20 patients with ocular pathologies and lens opacity (group 2) using Variable Contrast Visual Acuity Charts. Charts 1 and 4 have 90% contrast; chart 4 has white optotypes on a black background (reverse polarity), charts 2 and 3 have 15% and 2.5% contrast, respectively. The mean preoperative visual acuities of groups 1 and 2 measured with the high-contrast Landolt optotypes ranged from 0.02-0.80 and 0.22-0.40, respectively. Visual acuity improvements between the pre- and postoperative periods ranged from 1.37-1.61 and 0.52-1.24 octaves in groups 1 and 2, respectively, with the different charts. Visual acuity improvement was poorest with chart 3. The group 1 mean preoperative visual acuity measured with chart 2 was 1.11 octaves lower than with chart 1. In group 2, the visual acuity reduction was 1.81 octaves. The relation between the visual acuities measured with the high-contrast intermediate-contrast optotypes are important for predicting postoperative visual acuity improvement. An abnormal contrast acuity profile may indicate the presence of additional ocular pathologies.
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PMID:Contrast visual acuities in cataract patients. III. Changes of contrast acuity profiles in normal and pathological eyes. 762 60


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