Judith Friend

Antioxidant vitamins and nuclear opacities: the longitudinal study of cataract.

OBJECTIVE The association of antioxidant nutrients and risk of nuclear opacification was evaluated in the Longitudinal Study of Cataract. DESIGN Nutritional data were collected at baseline on the 764 participants, which included assessment of dietary intake, use of vitamin supplements, and plasma levels of vitamin E. Ophthalmologic and other data were collected at baseline and at yearly follow-up visits, including lens photographs, which were graded using the Lens Opacities Classification System III protocol. MAIN OUTCOME MEASURES Analyses examined whether the nutritional factors at baseline were related to increases in nuclear opacification at follow-up. The MULCOX2 approach, an extension of the Cox regression model, was used. Results are presented as relative risks (RRs) and 95% confidence intervals. INTERVENTION Intervention was not applicable. RESULTS The risk of nuclear opacification at follow-up was decreased in regular users of multivitamin supplements (RR = 0.69; 0.48-0.99), vitamin E supplements (RR = 0.43; 0.19-0.99), and in persons with higher plasma levels of vitamin E (RR = 0.58; 0.36-0.94). CONCLUSIONS In regular users of multivitamin supplements, the risk of nuclear opacification was reduced by one third; in regular users of vitamin E supplements and persons with higher plasma levels of vitamin E, the risk was reduced by approximately half. These results are similar to those obtained in our earlier case-control study. Because these data are based on observational studies only, the results are suggestive but inconclusive. The possible effect of nutritional supplements on the lens requires confirmation by ongoing clinical trials.

A Simple Method for the Removal of Rabbit Corneal Epithelium Utilizing n-Heptanol

A new method for removing corneal epithelial cells, using n-heptanol, is faster, more precise, and less damaging than scraping, which is the usual method of removing surface epithelium. We compared the results of n-heptanol removal with those of epithelial scraping, using scanning and transmission electron microscopy. Heptanol, unlike scraping, does not damage either the basement membrane or the extracellular stromal components. The rate of healing of corneal epithelium after heptanol treatment is similar to published observations of scraped corneas. Both scraping and heptanol destroy keratocytes, which underlie the basement membrane.

Biochemical Aspects of Contact Lens Wear

Glycogen, adenosine triphosphate, and hydration were measured in rabbit corneal epithelium to determine whether the corneal epithelium glycogen decrease, increase in epithelial hydration, and decrease in epithelial adenosine triphosphate stores, seen as a result of contact lens wear, were secondary only to anoxia or may also have resulted from mild trauma, with no interference to oxygenation. Conventional contact lens wear, trauma, and oxygen-permeable contact lens wear caused metabolic changes, showing trauma as well as anoxia may play an important role in the corneal epithelial response to contact lens wear. Language: en

The glycoprotein (mucus)content of tears from normals and dry eye patients.

Abstract Tears were sampled by two different methods from patients with ocular pemphigoid, Stevens-Johnsons Syndrome and Sjogrens Syndrome, as well as from normals. The tear glycoprotein (mucus) content was determined by measuring hexosamine after hydrolysis. Also hexuronic acid and protein levels were determined, as well as tear flow rate in some instances. The level of glycoprotein (mucus) in tears was markedly reduced in pemphigoid and Stevens-Johnson, diseases which are characterized by early break-up of the tear film and decreased content of mucus-producing conjunctival goblet cells. Mucus has earlier been shown to be necessary for the wetting of epithelium, but it is questionable whether mucus is reduced enough in pemphigoid and Stevens-Johnson to explain tear film instability in these disease entities.

Corneal Epithelial Changes in Diabetic Rats

Electron microscopy of streptozotocin diabetic rat eyes showed increased intracellular levels of tonofilaments and glycogen, thickenings and infoldings of subepithelial basement membrane and basal cell degeneration after 8 months. Glycogen, glucose, sorbitol, and fructose were measured in corneal epithelium from short- and long-term diabetic rats. The small increase in sorbitol pathway products which were found after 8 months of diabetes (less than 1.0 mosm/1 tissue water) confirmed similar findings in rabbits and humans. Thus, the morphologic changes occur in the absence of significant accumulation of sorbitol pathway products. Osmotic damage secondary to corneal epithelial cell accumulation of sorbitol is probably not a significant factor in corneal epithelial diabetic disease.

Effect of a corneal fluid barrier on the nutrition of the epithelium.

The effect of an intralamellar membrane on the epithelium was studied biochemically and bistologically. Metabolite levels in the corneal epithelium were determined by enzymatic optical tests after freezing the epithelium in vivo. After 1 week, the barrier resulted in a reduction of glucose, glycogen, and adenosine triphosphate levels, but did not affect lactate, pyruvate, adenosine diphosphate or adenosine monophosphate levels. Histochemically, the PAS reaction showed reduced glycogen in the central epithelium before other clinical or histological changes were seen. Neither tarsorrhaphy nor topical application of glucose solution or TC 199 could prevent this effect. If the membrane had a central hole, the epithelium over the hole remained normal in glycogen content and structure. These results indicate that the main source of energy for the epithelial metabolism is the aqueous humor.

Incidence and progression of nuclear opacities in the Longitudinal Study of Cataract.

PURPOSE To estimate incidence and progression rates of nuclear opacities in the Longitudinal Study of Cataract, an epidemiologic study of the natural history of all types of lens opacities. METHODS The Lens Opacities Classification System III was used to assess longitudinal changes between baseline and follow-up lens photographs for the 764 Longitudinal Study of Cataract participants. Baseline data, collected until December 1988 as part of a case-control study, included color slit, retroillumination, and Scheimpflug photographs. The same data were collected by the longitudinal Study of Cataract at four subsequent visits at yearly intervals. RESULTS Among patients free of nuclear opacities at baseline, the incidence of new opacities was 6% after 2 years and 8% after 5 years of follow-up. The progression of pre-existing nuclear opacities was much higher. After 2 years, nuclear opacities had progressed in more than one third of the patients with pre-existing opacities; after 5 years, almost half had progressed. Older age was significantly related to higher incidence of new nuclear opacities, but not to progression of pre-existing opacities. Patients with other opacity types had higher nuclear incidence and progression rates. CONCLUSIONS In this clinic-based, older-patient population, new nuclear opacities developed in less than one tenth of the patients after 5 years of follow-up. In contrast, almost one half of the patients with pre-existing opacities had worsened after 5 years. These estimated rates can be used to plan intervention or other studies of nuclear changes in similar populations.

Glucose Concentration and Hydration of the Corneal Stroma

Intralamellar membranes were implanted into rabbit corneas. After 1 and 3 weeks the cornea stromas were frozen in vivo. Anterior and posterior parts were then analyzed for glucose and hydration. The results showed significant glucose and hydration gradients from posterior to anterior in the normal cornea. The intralamellar membranes caused dehydration and reduction in the glucose content of the stroma anterior to it. This indicated that a lack of nutrition to the anterior cornea might be a factor in the development and persistence of complications in front of corneal fluid barriers.

Incidence and Progression of Cortical and Posterior Subcapsular Opacities: The Longitudinal Study of Cataract

OBJECTIVE The purpose of the study is to estimate incidence and progression rates of cortical and posterior subcapsular (PSC) opacities in the Longitudinal Study of Cataract (LSC). DESIGN An epidemiologic study of the natural history of lens opacities in a clinic-based population. PARTICIPANTS The LSC was based on 764 participants in an earlier case-control study of lens opacities. MAIN OUTCOME MEASURES Baseline data, collected until 1988, included color slit and retroillumination photographs. The same data were collected at follow-up visits from 1989 to 1993. The Lens Opacities Classification System III (LOCS III) was used to assess lens changes between baseline and follow-up photographs. The product-limit method was used to estimate the incidence and progression rates. RESULTS After 5 years of follow-up, the incidence rates for developing cortical and PSC opacities were 7.7% and 4.3%, respectively. The progression rate of pre-existing cortical opacities was 16.2% after 5 years, and was twice as high as the incidence rate. The progression of pre-existing PSC opacities was much higher, and reached 55.1% after 5 years of follow-up. The incidence of newly developed cortical or PSC opacities increased with age. The incidence of PSC opacities also increased when coexisting opacities were present at baseline. CONCLUSIONS After 5 years, 1 in every 13 patients developed new cortical opacities, and 1 in 24 developed new PSC opacities. The 5-year progression rates for cortical and PSC opacities were much higher than the incidence rates. These results can be used to estimate the rate of cortical and PSC changes in similar populations.

Validation of methods for the assessment of cataract progression in the Roche European-American AnticataractTrial (REACT)

The Roche European-American Anticataract Trial (REACT) will assess the effect of antioxidants on progression of cataract in humans. This report evaluates the methods used in REACT. Seventy three subjects (139 eyes) with cortical (C), posterior subcapsular (P), nuclear (N) or mixed cataract were seen twice within two weeks for eye examinations, assessments of visual function, lens photographs and CCD images. The degree of cataract and nuclear color (NC) were assessed with subjective (LOCS III) and objective (computerized, CASE 2000 CCD) methods. Repeat visit values were used to calculate intraclass correlation coefficients (r1) and 95% tolerance limits (TL). A clinically significant change (CSC) was defined as one step in LOCS III. The relative power of each method to detect cataract change and sample sizes needed to achieve statistically significant results were calculated. The r1 values for visual function tests ranged from 0.76 to 0.88; if these tests of visual function were used to detect a clinically significant change in cataract severity, sample sizes of 840 to 2707 per group would be needed. The r1 values for LOCS III were 0.88 to 0.97, and sample sizes ranged from 50 to 135 per group. The r1 values for the CCD were 0.93 to 0.98, and sample sizes ranged from 1 to 42 with poorer values relating to measurement of P. We conclude that the methods used in REACT are reproducible. The analytical algorithms in the image analysis programs did not permit differentiation between C and P opacification; therefore, P cataract is best measured with LOCS III. REACT sample sizes are adequate to detect a difference of 0.2 LOCS III units/year between the mean rates of cataract progression in two groups.