Retinal changes after retinal translocation surgery with scleral imbrication in dog eyes. (49/822)

PURPOSE: To examine retinal changes induced by scleral imbrication during retinal translocation surgery in dog eyes. METHODS: Fifteen dogs were anesthetized and underwent retinal translocation surgery. After lensectomy and vitrectomy, an intentional retinal detachment was created, and the upper temporal sclera around the equator was imbricated with five mattress sutures. Translocated distances were calculated by pre- and postoperative photographs. At 1, 2, and 4 weeks after the surgery, the retina was studied by TdT-dNTP terminal nick-end labeling (TUNEL) and immunohistochemistry of peanut agglutinin (PNA) lectin and glial fibrillary acidic protein (GFAP). RESULTS: The retina was translocated by a mean distance of 0.53 +/- 0.30 disc diameters or 959 +/- 543 micrometer. Retinal folds were created around the optic disc in all eyes. Histologic examination of the retinal folds 1 week after the surgery showed many TUNEL-positive cells in the outer nuclear layer, loss of photoreceptor cells, and shortening of the outer and inner segments. A strong immunoreactivity to GFAP was detected in the folds of the retina. CONCLUSIONS: . The results demonstrated that retinal translocation surgery by scleral imbrication inevitably caused retinal folds as a postoperative complication, and the retina within the folds showed extensive loss of photoreceptor cells. It is recommended that the foveal translocation surgery be planned to avoid involving the fovea in the retinal folds.  (+info)

Towards achieving small-incision cataract surgery 99.8% of the time. (50/822)

A surgical approach designed to reliably attain the modern goal of small incision cataract surgery 99.8% of the time is described. Phacoemulsification as well as a manual small incision technique is utilised to achieve the desired outcome as often as possible and for all types of cataracts. The logic, and required surgical steps are described and illustrated. This surgical technique allows the advantages of small incision surgery to be reliably achieved. The method is flexible and allows decisions and steps to be modified depending on the skill and comfort zone of the individual surgeon.  (+info)

Advanced glycation end products in human optic nerve head. (51/822)

AIMS: To localise advanced glycation end products (AGEs) in human optic nerve head. METHODS: Optic nerve samples from 13 elderly individuals (seven diabetics and six non-diabetics) were obtained at necropsy. Pyrraline, an advanced glycation end product, was immunohistochemically localised in the optic nerve heads. RESULTS: In the diabetic subjects, moderate to intense immunoreactivity for pyrraline was detected in sclera, pia mater, cribriform plates, connective tissues in the optic nerve, and around vessels in the optic nerve and pia mater. Immunoreactivity for pyrraline was also detected around retinal vessels. In the non-diabetic subjects, slight or no immunoreactivity for pyrraline was found in cribriform plates and around the optic nerve vessels. CONCLUSION: Accumulation of AGEs in cribriform plates and around vessels in the optic nerve may contribute to the development of optic neuropathy in diabetic patients.  (+info)

A new look at osteogenesis imperfecta. A clinical, radiological and biochemical study of forty-two patients. (52/822)

In a clinical, radiological and biochemical study of forty-two patients from Oxford with osteogenesis imperfecta, it was found that patients could be divided simply into mild, moderate and severe groups according to deformity of long bones. In the severe group (seventeen patients) a family history of affected members was uncommon and fractures began earlier and were more frequent than in the mild group (twenty-two patients); sixteen patients in the severe group had scoliosis and eleven had white sclerae; no patients in the mild group had white sclerae or scoliosis. Radiological examination of the femur showed only minor modelling defects in patients in the mild group, whereas in the severe group five distinct appearances of bone (thin, thick, cystic and buttressed bones, and those with hyperplastic callus) were seen. The polymeric (structural) collagen from skin was unstable to depolymerisation in patients in the severe group, but normal in amount, whereas the reverse was found in the mild group. This division according to long bone deformity may provide, a basis for future research more useful than previous classifications.  (+info)

The effect of scleral search coil lens wear on the eye. (53/822)

BACKGROUND/AIM: Scleral search coils are used to measure eye movements. A recent abstract suggests that the coil can affect the eye by decreasing visual acuity, increasing intraocular pressure, and damaging the corneal and conjunctival surface. Such findings, if repeated in all subjects, would cast doubt on the credibility of the search coil as a reliable investigative technique. The aim of this study was to reassess the effect of the scleral search coil on visual function. METHODS: Six volunteer subjects were selected to undergo coil wear and baseline measurements were taken of logMAR visual acuity, non-contact tonometry, keratometry, and slit lamp examination. Four drops of 0.4% benoxinate hydrochloride were instilled before insertion of the lens by an experienced clinician. The lens then remained on the eye for 30 minutes. Measurements of the four ocular health parameters were repeated after 15 and 30 minutes of lens wear. The lens was then removed and the health of the eye reassessed. RESULTS: No obvious pattern of change was found in logMAR visual acuity, keratometry, or intraocular pressure. The lens did produce changes to the conjunctival and corneal surfaces, but this was not considered clinically significant. CONCLUSION: Search coils do not appear to cause any significant effects on visual function. However, thorough prescreening of subjects and post-wear checks should be carried out on all coil wearers to ensure no adverse effects have been caused.  (+info)

Differences in time course and visual requirements of ocular responses to lenses and diffusers. (54/822)

PURPOSE: Myopia can be induced in chickens by having them wear either negative lenses (lens-compensation myopia [LCM]) or diffusers (form-deprivation myopia [FDM]), whereas positive lenses cause lens-compensation hyperopia (LCH). These three conditions were compared with respect to (i) their early time course and (ii) the effect of two manipulations of the lighting. METHODS: Longitudinal changes in ocular dimensions and refractive error were measured in chicks maintained under three different conditions: (i) wearing either -15 D lenses or diffusers in a normal light/dark cycle; (ii) wearing either +15 D lenses, -15 D lenses, or diffusers with brief periods of stroboscopic lights at the beginning and end of the dark period; (iii) wearing either +6 D lenses, -6 D lenses, or diffusers with the nights interrupted by brief periods of white light. In addition, scleral and choroidal proteoglycan synthesis was measured in eyes that wore positive lenses, negative lenses, or diffusers for 3 hours followed by different periods of darkness. RESULTS: (i) The time course of the changes in axial length over the first 72 hours was significantly faster in LCM than in FDM. Indeed, the diffusers did not begin to significantly affect the total length of the globe for 3 days, although the vitreous chamber had deepened after 9 hours, because the choroid thinned extremely rapidly (within 1 hour) with either diffusers or negative lenses. (ii) Scleral proteoglycan synthesis was higher in eyes with negative lenses than in those with diffusers at 11 hours, but the reverse was true at 27 hours. (iii) Brief periods of stroboscopic light attenuated FDM more than LCM. (iv) In contrast, interruption of the nights by brief periods of light attenuated LCM more than FDM. (v) Neither lighting manipulation affected LCH. (vi) Choroidal proteoglycan synthesis decreased similarly with 3 hours of wearing either diffusers or negative lenses. CONCLUSIONS: Although both negative lenses and diffusers cause similar increases in the rate of ocular elongation, the responses differ in time course and in the effect of manipulations of the daily lighting. The responses to positive lenses differ from both of these.  (+info)

Steady state mRNA levels in tree shrew sclera with form-deprivation myopia and during recovery. (55/822)

PURPOSE: In tree shrews, visual form deprivation induces myopia and tissue remodeling in the sclera, characterized by decreased levels of collagen and glycosaminoglycans (GAGs) and increased levels of matrix metalloproteinases (MMPs). Removal of the visual deprivation allows recovery. This study investigated whether these changes are accompanied by changes in steady state mRNA levels in the sclera. METHODS: Quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR) was used to measure steady state levels of mRNA for collagen (alpha1(I) chain), decorin (core protein), gelatinase-A (MMP-2), stromelysin-1 (MMP-3), and a tissue inhibitor of metalloproteinase (TIMP-1) in the scleras of tree shrews that received either 11 days of monocular form deprivation (MD) or 11 days of MD followed by 4 days of recovery. A group of age-matched normal animals was also measured. RESULTS: After 11 days of MD, alpha1(I) collagen mRNA levels were 34% lower, and MMP-2 mRNA levels were 66% higher in the deprived eyes than in the control eyes. After 4 days of recovery, collagen mRNA levels were 33% higher, MMP-2 levels were 20% lower, and TIMP-1 levels were 43% higher in the recovering eyes than in the control eyes. Decorin and MMP-3 mRNA levels were not significantly different between the treated and control eyes after MD or after recovery. CONCLUSIONS: The tissue remodeling in mammalian sclera induced by altering the visual environment is accompanied by modulation of mRNA levels in the sclera. The levels of collagen and MMP-2 mRNA were modulated in a pattern generally consistent with observed changes in protein levels, suggesting that visual regulation of the levels of these scleral proteins may involve modulation of gene expression at the transcriptional level.  (+info)

Expression and localization of angiogenic inhibitory factor, chondromodulin-I, in adult rat eye. (56/822)

PURPOSE: To determine the role in the eye of chondromodulin (ChM)-I, which has been identified in cartilage as an angiogenic inhibitor, the expression and localization and a possible function of ChM-I were investigated. METHODS: Expression and localization of ChM-I in rat eyes were examined by RNase protection assay and in situ hybridization and by immunostaining, using an antibody against a synthetic peptide. The effect of recombinant ChM-I on tube morphogenesis of retinal endothelial cells was examined in culture. RESULTS: The rat ChM-I gene was determined to encode the open reading frame of 334 amino acid residues, and ChM-I mRNA was exclusively expressed in cartilage, eye, and cerebellum in rats. ChM-I mRNA expression was evident in the iris-ciliary body, retina, and scleral compartments, but not in other compartments of the eye. In situ hybridization revealed mRNA expression in the ganglion cells, inner nuclear layer cells, and pigment epithelium in the retina and in the nonpigment epithelium of the ciliary body. Immunoreactive ChM-I was present in these cells and also in the vitreous body. Western blot analysis detected an approximately 25-kDa band of ChM-I presumed as a secretory form in the aqueous humor and vitreous body and an approximately 37-kDa band as a precursor form in the retina. Recombinant human ChM-I inhibited tube morphogenesis of human retinal endothelial cells in vitro. CONCLUSIONS: These observations indicate a potential role for ChM-I in inhibition of angiogenesis in the rat eye.  (+info)