Changes In Ocular Tissues Research Articles

IMI-Nonpathological Human Ocular Tissue Changes With Axial Myopia.

To describe nonpathological myopia-related characteristics of the human eye. Based on histomorphometric and clinical studies, qualitative and quantitative findings associated with myopic axial elongation are presented. In axial myopia, the eye changes from a spherical shape to a prolate ellipsoid, photoreceptor, and retinal pigment epithelium cell density and total retinal thickness decrease, most marked in the retroequatorial region, followed by the equator. The choroid and sclera are thin, most markedly at the posterior pole and least markedly at the ora serrata. The sclera undergoes alterations in fibroblast activity, changes in extracellular matrix content, and remodeling. Bruch's membrane (BM) thickness is unrelated to axial length, although the BM volume increases. In moderate myopia, the BM opening shifts, usually toward the fovea, leading to the BM overhanging into the nasal intrapapillary compartment. Subsequently, the BM is absent in the temporal region (such as parapapillary gamma zone), the optic disc takes on a vertically oval shape, the fovea-optic disc distance elongates without macular BM elongation, the angle kappa reduces, and the papillomacular retinal vessels and nerve fibers straighten and stretch. In high myopia, the BM opening and the optic disc enlarge, the lamina cribrosa, the peripapillary scleral flange (such as parapapillary delta zone) and the peripapillary choroidal border tissue lengthen and thin, and a circular gamma and delta zone develop. A thorough characterization of ocular changes in nonpathological myopia are of importance to better understand the mechanisms of myopic axial elongation, pathological structural changes, and psychophysical sequelae of myopia on visual function.

Water-filtered Infrared A and visible light (wIRA/VIS) treatment reduces Chlamydia caviae-induced ocular inflammation and infectious load in a Guinea pig model of inclusion conjunctivitis

Trachoma is a devastating neglected tropical disease caused by Chlamydia trachomatis and the leading global cause of infectious blindness. Although antibiotic treatment against trachoma is efficient (SAFE strategy), additional affordable therapeutic strategies are of high interest. Water-filtered infrared A and visible light (wIRA/VIS) irradiation has proven to reduce chlamydial infectivity in vitro and ex vivo. The aim of this study was to evaluate whether wIRA/VIS can reduce chlamydial infection load and/or ocular pathology in vivo, in a guinea pig model of inclusion conjunctivitis. Guinea pigs were infected with 1 × 106 inclusion-forming units/eye of Chlamydia caviae via the ocular conjunctiva on day 0. In infected animals, wIRA/VIS irradiation (2100 W/m2) was applied on day 2 (single treatment) and on days 2 and 4 (double treatment) post-infection (pi). wIRA/VIS reduced the clinical pathology score on days 7 and 14 pi and the conjunctival chlamydial load on days 2, 4, 7, and 14 pi in comparison with C. caviae-infected, not irradiated, controls. Furthermore, numbers of chlamydial inclusions were decreased in wIRA/VIS treated C. caviae-infected guinea pigs on day 21 pi compared to C. caviae-infected, non-irradiated, controls. Double treatment with wIRA/VIS (days 2 and 4 pi) was more efficient than a single treatment on day 2 pi. wIRA/VIS treatment did neither induce macroscopic nor histologic changes in ocular tissues. Our results indicate that wIRA/VIS shows promising efficacy to reduce chlamydial infectivity in vivo without causing irradiation related pathologies in the follow-up period. wIRA/VIS irradiation is a promising approach to reduce trachoma transmission and pathology of ocular chlamydial infection.

Historical Data: Histopathology Lesions Observed in the Eyes of Control Rabbits in Topical Ocular Administration and Contact Lens Studies.

Information on background changes in the ocular tissues of rabbits ( Oryctolagus cuniculus), a common species employed in ophthalmic toxicology studies, is sparse. This complicates interpretation of changes in light of small sample sizes on any single study. The purpose of this publication is to document the interstudy incidence of spontaneous or iatrogenic changes occurring in eyes of control rabbits. Photomicrographs of select lesions are provided. The data set was derived from a total of 54 studies conducted over an eleven-year period at Alcon Research Ltd., a Novartis Division, which featured topical ocular and contact lens routes of administration. It includes a total of 1,222 pigmented and albino New Zealand rabbits and a total of 2,084 eyes which were either untreated or treated with innocuous control articles. There were no noteworthy differences across routes of administration. Changes in anterior segment ocular and adnexal tissues were more common than in posterior segment ocular tissues. Overall, mononuclear cell infiltration was the most common finding. The retina was the posterior tissue most commonly observed with spontaneous changes, with folds and rosettes being the most common retinal finding. Retinal changes were more common in albino as compared to pigmented rabbits. Understanding the incidence and characteristics of spontaneous ocular lesions facilitates accurate and consistent diagnosis and data interpretation.

Aldose reductase, ocular diabetic complications and the development of topical Kinostat(®).

Diabetes mellitus (DM) is a major health problem with devastating effects on ocular health in both industrialized and developing countries. The control of hyperglycemia is critical to minimizing the impact of DM on ocular tissues because inadequate glycemic control leads to ocular tissue changes that range from a temporary blurring of vision to permanent vision loss. The biochemical mechanisms that promote the development of diabetic complications have been extensively studied. As a result, a number of prominent biochemical pathways have been identified. Among these, the two-step sorbitol pathway has been the most extensively investigated; nevertheless, it remains controversial. To date, long-term pharmacological studies in animal models of diabetes have demonstrated that the onset and development of ocular complications that include keratopathy, retinopathy and cataract can be ameliorated by the control of excess metabolic flux through aldose reductase (AR). Clinically the alleles of AR have been linked to the rapidity of onset and severity of diabetic ocular complications in diabetic patient populations around the globe. In spite of these promising preclinical and human genetic rationales, several clinical trials of varying durations with structurally diverse aldose reductase inhibitors (ARIs) have shown limited success or failure in preventing or arresting diabetic retinopathy. Despite these clinical setbacks, topical ARI Kinostat(®) promises to find a home in clinical veterinary ophthalmology where its anticipated approval by the FDA will present an alternative treatment paradigm to cataract surgery in diabetic dogs. Here, we critically review the role of AR in diabetes mellitus-linked ocular disease and highlight the development of Kinostat(®) for cataract prevention in diabetic dogs. In addition to the veterinary market, we speculate that with further safety and efficacy studies in humans, Kinostat(®) or a closely related product could have a future role in treating diabetic keratopathy.

Scleral cross-linking by riboflavin and blue light application in young rabbits: damage threshold and eye growth inhibition.

Scleral cross-linking (SXL) by riboflavin and light application has been introduced as a possible treatment to increase scleral tissue stiffness and to inhibit excessive axial elongation of highly myopic eyes. We evaluated an ocular tissue damage threshold for blue light irradiation, and used SXL treatment to induce eye growth inhibition. The sclera of 3-week-old rabbits (39 pigmented and 15 albino rabbits) were treated with different blue light intensities (450 ± 50 nm) and riboflavin. Alterations and a damage threshold were detected in ocular tissues by means of light microscopy and immunohistochemistry. The influence of SXL on the eye growth was examined in 21 young rabbits and was measured by using A-scan ultrasonography, micrometer caliper, and for selected eyes additionally by MR imaging. Light microscopic examinations demonstrated degenerative changes in ocular tissue after irradiation with blue light intensities above 400 mW/cm(2) (with and without riboflavin application). Therefore, that light intensity was defined as the damage threshold. Tissue alteration in retina, choroid, and sclera and activation of retinal microglia cells and Müller cells could be earlier observed at blue light intensities of 150 and 200 mW/cm(2). Albino rabbits were less sensitive to this SXL treatment. A significant reduction of the eye growth could be detected by SXL treatment with the minimal efficient blue light intensity of 15 mW/cm(2) and maintained stable for 24 weeks. SXL with riboflavin and blue light intensities below a defined damage threshold can induce a long lasting growth inhibitory effect on young rabbit eyes. Therefore, SXL might be a realistic approach to inhibit eye elongation in highly myopic eyes.

Effects of EGCG content in green tea extract on pharmacokinetics, oxidative status and expression of inflammatory and apoptotic genes in the rat ocular tissues

Green tea extract (GTE) exerts antioxidative activities in ocular tissues of rats, but high levels of (−)-epigallocatechin gallate (EGCG) can induce oxidative stress. In this study, pharmacokinetics, diurnal variation of oxidative status, antioxidation and transcription factors changes in ocular tissues of rats were investigated. Rats were fed intragastrically with GTE and catechin mixtures containing different amounts of EGCG. Plasma and various ocular tissues were taken for pharmacokinetic analysis, oxidation marker testings and gene expression assays. Effects of EGCG on ocular oxidation status were assessed by 8-isoprostane level and reduced/oxidized glutathione ratio. Oxidation, inflammation and apoptosis regulations in retina were evaluated by real-time polymerase chain reaction. Epicatechin, epigallocatechin and EGCG were dominant in various ocular tissues except vitreous humor, where gallocatechin was predominant. Diurnal variation of oxidative status was found in some compartments. GTE caused oxidative stress increase in the plasma, aqueous humor, vitreous humor, cornea and retina but decrease in the lens and choroid–sclera. Catechins mixture containing half dose of EGCG lowered 8-isoprostane in the retina and lens. GTE treatment induced superoxide dismutase 1 and glutathione peroxidase-3 expressions but suppressed catalase in the retina. Our results reveal pro-oxidation of GTE with high EGCG content to the ocular tissues. Optimal EGCG level is needed for protection.

Damage threshold in adult rabbit eyes after scleral cross-linking by riboflavin/blue light application

Several scleral cross-linking (SXL) methods were suggested to increase the biomechanical stiffness of scleral tissue and therefore, to inhibit axial eye elongation in progressive myopia. In addition to scleral cross-linking and biomechanical effects caused by riboflavin and light irradiation such a treatment might induce tissue damage, dependent on the light intensity used. Therefore, we characterized the damage threshold and mechanical stiffening effect in rabbit eyes after application of riboflavin combined with various blue light intensities. Adult pigmented and albino rabbits were treated with riboflavin (0.5 %) and varying blue light (450 ± 50 nm) dosages from 18 to 780 J/cm2 (15 to 650 mW/cm2 for 20 min). Scleral, choroidal and retinal tissue alterations were detected by means of light microscopy, electron microscopy and immunohistochemistry. Biomechanical changes were measured by shear rheology. Blue light dosages of 480 J/cm2 (400 mW/cm2) and beyond induced pathological changes in ocular tissues; the damage threshold was defined by the light intensities which induced cellular degeneration and/or massive collagen structure changes. At such high dosages, we observed alterations of the collagen structure in scleral tissue, as well as pigment aggregation, internal hemorrhages, and collapsed blood vessels. Additionally, photoreceptor degenerations associated with microglia activation and macroglia cell reactivity in the retina were detected. These pathological alterations were locally restricted to the treated areas. Pigmentation of rabbit eyes did not change the damage threshold after a treatment with riboflavin and blue light but seems to influence the vulnerability for blue light irradiations. Increased biomechanical stiffness of scleral tissue could be achieved with blue light intensities below the characterized damage threshold. We conclude that riboflavin and blue light application increased the biomechanical stiffness of scleral tissue at blue light energy levels below the damage threshold. Therefore, applied blue light intensities below the characterized damage threshold might define a therapeutic blue light tolerance range.

Histologic and spectroscopic study of pluripotent stem cells after implant in ocular traumatic injuries in a murine model

IntroductionOcular trauma is defined as a trauma caused by blunt or penetrating mechanisms on the eyeball and its peripheral structures, causing damage with different degrees of affection with temporary or permanent visual function compromise. Ocular trauma is a major cause of preventable blindness worldwide; it constitutes 7% of all corporal injury and 10% to 15% of all eye diseases. Regenerative medicine research has opened up the possibility to use stem cells as a source of cell replacement, so that experimental studies on embryonic stem cells and bone marrow stem cells have been carried out. In this study, we analyzed the histopathological and spectroscopic changes in ocular tissue with trauma, treated with mouse pluripotent stem cells.MethodsFirstly, mouse embryonic stem cells were seeded. Subsequently, the obtained cells were implanted in a murine model of scleral and retinal damage at the first, second, and fourth weeks post-trauma. At week 12 post-trauma, the eyes were enucleated for histopathologic study (inflammatory response and histological integrity) and spectroscopic analysis by Fourier transform infrared spectroscopy in the attenuated total reflection configuration. Data were analyzed by one-way analysis of variance.ResultsHistopathological results showed that the experimental groups treated with stem cells presented a decrease in the inflammatory response, and the histological integrity was restored, which contrasted with the experimental group treated with saline solution. Moreover, in the spectroscopic analysis, characteristic bands of biological samples were observed in all tissues, highlighting in healthy tissues the presence of C = O bond at 1,745 cm-1, which was not observed in the injured and treated tissues. Also, the absorption spectrum of the tissues treated with embryonic stem cells showed bands whose intensity was high at around 1,080 to 1,070 cm-1. It has been reported that these bands are characteristic of pluripotent stem cells.ConclusionsThe implant of embryonic stem cells could be a useful therapeutic treatment after traumatic eye injuries or many other eye diseases to reduce the inflammatory response and restore histological integrity. Furthermore, the spectroscopic technique could be used as a complementary technique for detecting stem cell incorporation into various tissues.

Hypoxia–Reoxygenation Affects Whole-Genome Expression in the Newborn Eye

Resuscitation of newborns is one of the most frequent procedures in neonatal medicine. The use of supplementary oxygen during resuscitation of the asphyxiated newborn has been shown to be detrimental to vulnerable tissues. We wanted to assess transcriptional changes in ocular tissue after the acute use of oxygen in the delivery room in a hypoxia-reoxygenation model of the newborn mouse. C57BL/6 mice (n = 57), postnatal day 7, were randomized to receive either 120 minutes of hypoxia, at 8% O2, followed by 30 minutes of reoxygenation with 21, 40, 60, or 100% O2 or to normoxia followed by 30 minutes of 21% or 100% O2. Whole ocular homogenates were analyzed by Affymetrix 750k expression array, and RT-PCR was performed for validation. Bayesian analysis of variance for microarray data (BAMarray) was used to identify single significant genes, and Gene Set Enrichment Analysis (GSEA) was applied to reveal significant pathway systems. In total, ∼ 92% of the gene expression changes were altered in response to reoxygenation with 60% or 100% O2 compared to expression at the lower percentages of 21% and 40%. After 100% O2 treatment, genes involved in inflammation (Ccl12), angiogenesis (Igfr1, Stat3), and metabolism (Hk2) were upregulated. Pathway analyses after hypoxia-reoxygenation revealed significant alterations of six pathways which included apoptosis, TGF-beta signaling, oxidative phosphorylation, voltage-gated calcium channel complex, mitochondrion, and regulation of RAS protein signal transduction. Hypoxia-reoxygenation can induce immediate transcriptional responses in ocular tissue involving inflammation, angiogenesis, energy failure, and Ras signaling.

Videografie mit der Spaltlampe

Many new diagnostic instruments have been introduced for imaging in ophthalmology, particularly for retinal diseases and diagnostics in glaucoma. The slit lamp, however, as the most important instrument in practical ophthalmological work, has been largely unchanged for decades. It will be shown that a video slit lamp can be used for monitoring of a much broader spectrum of ophthalmological diseases than is commonly used at present. We name the required methods and techniques collectively videography. There are only few additional technical requirements (fundus lenses, minus lenses, recentration prism, generally available computer programmes). The following methods and techniques are applied in slit lamp videography: 1) special considerations of illumination; 2) sequential analysis of video recordings; 3) picture composites especially for topographic overviews; 4) the flicker test to detect changes in ocular tissue by virtual movement. These methods and techniques of videography open new fields for slit lamp imaging in ophthalmology - equally of the retina (e.g., follow-up in glaucoma and macular disease) and face (e.g., photography of squint). Illustrative examples are given. Ophthalmologists, especially those without access to a professional photographic unit, should be encouraged that with a video slit lamp nearly all clinical findings can be documented efficiently if clear concepts - as given by videography - exist as to what is to be done.

The effect of the YK lens in keratoconus

To report the clinical results of the use of the YK contact lens (Lucid Co., Seoul, Korea) for keratoconus. One hundred and twenty nine keratoconic eyes were fitted with a YK lens which has one base curve and three peripheral curves. A light feather touch fluorescein pattern was obtained based on topographic indices. Visual acuity, comfort, mean wearing time, and ocular tissue changes were evaluated. Mean follow up was 17.5 +/- 13.8 months (range 6-75). One hundred and twenty six (97.6%) eyes tolerated the contact lenses. A total of 94.5% of the eyes achieved a visual acuity of 20/40 or better (average 0.79 +/- 0.21), and flatter base curve radius (BCR) was related to better visual acuity. One hundred and seventeen (90.7%) eyes reported that the lenses were comfortable. Mean wearing time was 12.1 h per day (range 4-18). Changes in keratometric values were not significant between baseline and final follow-up visit. The YK lens can provide successful visual outcome, with comfort, and no significant influence on the progression of keratoconus.

A review of the use of Streptozotocin (STZ) in the induction of diabetes in rats and subsequent ocular tissue changes

Streptozotocin is widely used in medical research for treating certain cancers of the Islets of Langerhans and to produce an animal model for type 1 diabetes. A study has revealed that when compared to the control group of rats, those injected with STZ exhibited reduced plasma insulin and elevated blood glucose (p < 0.05 in all cases). The study also found that diabetic rats weighed significantly less than control animals (p < 0.05). In relation to ocular tissues, lacrimal glands from diabetic rats were also found to weigh significantly less (p < 0.05) than those from the control group. However, no significant changes in the weights of lens, cornea, sclera and retina were observed between diabeticand control animals. Several other studies found that STZ-induced diabetes can be treated by plant extracts which control the blood sugar level as well as improving the lipid profile and ocular complications such as retinopathy. Experiments are usuallyperformed on male or female rats of a specific body weight, usually between 250 and 300 g. Diabetes is induced in rats by intraperitonial injections of streptozotocin (60 mg/ kg) in citrate buffer, pH 6.3.Animals that exhibit glucosuria after 24 hours, test-ed by urine test strips are considered diabetic. Plant extracts (6 mg/100g body weight) are orally administered into the stomach of STZ-diabetic rats every third day at a certain consistent time by means of bulbed steel needle for at least a four week period. This is done to determine the efficacy and potency of the plant extracts on diabetes. Histological and transmission electron microscope (TEM) techniques are used to study the changes in the ocular tissues. The dissected ocular tissues should be dehydrated in graded ethyl alcohol series and embedded in Araldite CY212. Ultra thin sections should be contrasted with uranyl acetate and lead citrate for examination by TEM. Streptozotocin induces diabetes in laboratory animal models for scientific studies and breakthroughs in medicine. The use of STZ and plant extracts may prove to be beneficial in the eye health care profession if considered for the studies of hypoglycemic agents that have the potency to prevent the advancement of diabetic retinopathy in diabetic patients.

Intraocular Pressure Spikes in Keratectasia, Axial Myopia, and Glaucoma

To review a range of activities associated with intraocular pressure (IOP) spikes. To examine the possible significance of IOP spikes in conditions such as keratectasia, axial myopia, and glaucoma. Hypotheses concerning mechanisms for adverse responses to IOP spikes were examined. Apart from the possibility that IOP spikes might cause susceptible corneal, posterior scleral, or optic nerve head tissue to yield to associated distending forces, there is the possibility that these tissues will be also be damaged by increased hydrostatic pressure. In-office tonometry does not indicate the degree to which ocular tissues are exposed to IOP spikes. For eyes that are exposed to IOP spikes of longer duration, that occur frequently and which result in a larger IOP increment, the risk of an adverse response may be greater. Changes in ocular tissues because of increased hydrostatic pressure may include morphological cellular changes and alterations to enzyme function. Eye rubbing may be the most significant mechanism for creating IOP spikes because of the large IOP increments that may be involved, as well as the possibility that abnormal rubbing can become a chronic habit. As appears to be the case in keratoconus, asymmetric exposure to IOP spikes may help to explain some asymmetric presentations of post-laser-assisted in situ keratomileusis, glaucoma, or myopia. Ideally methods for the objective assessment of patient risk for adverse responses to IOP spikes will continue to be developed. A self-administered questionnaire may help identify patients who are significantly exposed to IOP spikes. Family history may indicate an increased risk of diseases for which IOP spikes may have significant implications. Patient counseling regarding the possibility that IOP spiking activities may contribute to the development and/or progression of conditions such as keratectasia, axial myopia, and glaucoma may be indicated.

Changes in growth factor expression in normal aging of the rat retina

Although much is known about the growth factor changes in ocular tissues during various diseases, little is known about normal aging of the retina. In order to further understand normal aging in the retina, we characterized age-related changes of growth factor expression in three different ages of rat retina. Real time PCR and protein analysis was conducted to investigate steady state mRNA expression and protein levels of VEGF, VEGFR2, PEDF, Ang-1, Tie-2, EphB4 and ephrinB2 in the retina of 8-, 22-, and 32-month-old Brown Norway X Fischer 344 F1 hybrid rats. An increase of VEGF protein levels was found at 32 months compared to 8 and 22 months of age. VEGFR2 protein was found to be increased at 22 and 32 months compared to 8 months. PEDF protein levels were reduced at 22 and 32 months. Tie-2 levels were found to be significantly decreased by 32 months compared to 8 months of age, while ephrinB2 was found to be significantly lower at both 22 and 32 months compared to 8 months of age. The increases found in VEGF and its receptor VEGFR2, with the simultaneous decrease of PEDF protein levels, may stimulate an environment that is well suited for neovascularization in the normal aging retina. Overall, these results suggest that normal aging produces substantial changes in gene expression and protein levels.

Effects of streptozotocin-induced type 1 diabetes mellitus on protein and ion concentrations in ocular tissues of the rat

This study investigated the effects of streptozotocin (STZ)-induced diabetes mellitus (DM) on protein and cation levels inocular tissues (lenses, cornea, lacrimal glands and retina with sclera) of rats. Diabetic rats and their lacrimal glands weighedsignificantly less (p < 0.05) than age-matched controls. Diabetic animals also had significantly (p < 0.05) elevated bloodglucose and significantly reduced (p < 0.05) plasma insulin compared to controls. Total protein concentrations in the cornea,lens, lacrimal gland and retina with sclera were markedly reduced compared to controls (circa 50%-90%). Diabetic cornea,lenses, lacrimal glands, and retina with sclera contained more Ca2+ (p < 0.05) than age-matched controls (2-3 fold). Levels ofZn2+ were also elevated (p < 0.05) in the cornea and retina with sclera of diabetic rats, as compared to control rats (2-3 fold),but were unaffected in lenses and lacrimal glands. In contrast, levels of Cu2+, Mg2+, Na+ and K+ were significantly reduced (p< 0.05) in all ocular tissues of diabetic rats when compared to control animals (circa 30%-70%). These results show thatSTZ-induced DM is generally associated with significant physiochemical changes in ocular tissues of rats with changesobserved in body weight, blood glucose, and insulin levels and protein and cation concentrations compared to healthy agematchedcontrols. Based on these data, it has been speculated that diabetes may induce changes in ocular tissues that include:higher protein turnover through increased protease activity and changes in Na+ / K+ channel function. It is suggested thatthese changes may be associated with diabetic retinopathy, diabetic cornea and sight impairment. (Int J Diabetes Metab13:154-158, 2005)

A different amyloid formation mechanism: de novo oculoleptomeningeal amyloid deposits after liver transplantation.

Liver transplantation has served as a treatment for patients with familial amyloidotic polyneuropathy (FAP) because variant transthyretin (TTR), the pathogenic protein of FAP, is predominantly produced by the liver. However, the effect on amyloid formation of TTR that is synthesised by the retina and the choroid plexus remains to be elucidated in FAP patients with liver transplants. To investigate changes in ocular tissues and the central nervous system (CNS) of FAP patients after liver transplantation. Clinical study. Graduate School of Medical Sciences, Kumamoto University, Japan. Transplantation of livers from cadaveric or living donors. Preoperative measures and postoperative (16-108 months) follow-up of clinical data, including routine ophthalmologic, neurologic, and laboratory evaluations. In 22 patients with FAP related to the amyloidogenic TTR (ATTR) Val30Met and 3 patients with FAP ATTR Tyr114Cys, after liver transplantation, 3 patients began to show evidence of de novo glaucoma, and 1 had vitreous opacity that was caused by the variant TTR. Another three patients showed new amyloid deposits in the pupillary margin, which could lead to glaucoma and vitreous opacity. As for changes in the CNS and levels of total protein and TTR in cerebrospinal fluid (CSF), after liver transplantation, two FAP ATTR Tyr114Cys patients exhibited de novo amyloid deposition in the leptomeninges, and total protein and TTR levels in CSF were significantly increased. Oculoleptomeningeal involvement in FAP was not prevented by liver transplantation because variant TTR produced by the retina and the choroid plexus forms amyloid fibrils in situ.

CCLRU Standards for Success of Daily and Extended Wear Contact Lenses

Success in contact lens wear is often judged on the basis of patient "survival" rather than the achievement of satisfactory performance based on specific criteria. In 1971, Sarver and Harris defined a series of standards for successful polymethyl methacrylate (PMMA) lens wear which incorporated criteria for wearing time, comfort, vision, ocular tissue changes, and patient appearance. In this paper we propose a revision of these criteria based on current understanding of the ocular response to contact lens wear. These revised CCLRU (Cornea and Contact Lens Research Unit) standards for success are intended as realistic performance objectives, and can be applied in clinical trials to evaluate and compare the clinical performance of present and future rigid and soft contact lenses, worn for daily and extended wear.

Ocular side effects of phenothiazines

It has been shown that prolonged usage of phenothiazine drugs causes tissue changes in the eye. Such changes were evaluated in 19 long-term psychiatric patients who had taken phenothiazines over periods ranging from five to 32 years to assess whether decreased contrast sensitivity function and colour vision anomalies could be used as indicators of ocular tissue change. Using Vistech gratings, contrast sensitivity was found to be below normal at 6,12 and 18 cycles per degree in 45 per cent, 16 per cent and 39 per cent of the eyes respectively. The Farnsworth Dichotomous Panel D15 test revealed colour vision anomalies in more than half the eyes. However, linear regression analysis showed no systematic relationship between the results of either test and the degree of ocular tissue changes observed.

Histology of Ocular Late-Phase Reaction in Guinea Pigs Passively Sensitized with IgGl Antibodies

The ocular late-phase reaction (LPR) is a mast cell-dependent, delayed inflammatory reaction developing 4-12 h after the early-phase reaction (EPR). We developed a passive IgG1 antibody-dependent guinea pig model that clinically reproduced the biphasic reaction of ocular EPR and LPR. An EPR was observed in all animals; a biphasic, multiphasic or prolonged inflammation was observed in the animals maintained for 9 and 24 h. The substantia propria of eyes undergoing EPR (0.5 h) showed intense edema, mast cell degranulation (88%), and 4-fold increase in eosinophils. At 9 h, the neutrophils and eosinophils had increased 11- and 25-fold, respectively. The number of basophils and lymphocytes was significantly increased compared to the controls (p less than 0.05). Of the mast cells, 45% were degranulated compared with 19% for controls. Cellular reactions had subsided by 24 h. Conjunctival epithelium also accumulated inflammatory cells as did the stroma of the lid skin. These histologic changes in ocular tissues undergoing anaphylaxis demonstrated that mast cell degranulation was most severe in the early phase, whereas neutrophil, eosinophil, and basophil accumulation was most marked in the late phase.

Reversal of Abnormalities in Ocular Fluorophotometry in Insulin-dependent Diabetes After Five to Nine Months of Improved Metabolic Control

Abnormalities in ocular fluorophotometry occur in human and experimental diabetes mellitus. To determine the reversibility of these abnormalities, we studied prospectively 11 intensively treated and 25 conventionally treated insulin-dependent diabetics (IDD) preselected because of abnormal vitreous fluorophotometry. Among the 25 IDD treated conventionally with one or two insulin injections daily, hemoglobin A 1C concentrations remained elevated and fluorescein concentration, 1 h after the intravenous injection of fluorescein (7 mg/kg), did not change significantly in either the anterior chamber or the posterior vitreous. Among 11 IDD treated intensively with home blood glucose monitoring and pumped subcutaneous insulin or three or more injections daily, hemoglobin A 1C fell dramatically (10.4 ± 0.7% to 7.5 ± 0.2%) and anterior chamber fluorescein concentration decreased (73.9 ± 7.7 to 49.5 ± 5.3 ng/ml). Two patients with proliferative retinopathy showed no improvement in their massive vitreous fluorescein accumulation and subsequently required photocoagulation. In the nine subjects without proliferative retinopathy, vitreous fluorescein accumulation decreased in eight (10.6 ± 0.7 to 6.5 ± 0.5 ng/ml) and was normal in six after 1 yr. The only subject with increasing vitreous fluorescein accumulation also had concurrent worsening of background retinopathy. These studies support the hypothesis that moderate abnormalities in ocular fluorophotometry are due to reversible changes in ocular tissues, such as retinal pigment epithelium. Fluorescein leakage emanating from the advanced vascular or retinal abnormalities of proliferative retinopathy were not reversed with the degree and duration of metabolic control achieved in the present study. The long-term significance of the reversal of moderate abnormalities in fluorophotometry is not clear at the present time.