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At least 163 records · Page 9Linked to original sources
PubMed2000

In vitro diffusion of mitomycin-C into human sclera after episcleral application: impact of diffusion time.

The purpose of this study was to investigate the impact of different diffusion times of mitomycin-C (MMC) on the intrascleral concentration vs depth profile of MMC in an experimental model. Scleral quadrants of eight human donor eyes were exposed to sponges soaked with MMC for an application time of 1 min. After irrigation with 40 ml saline, we allowed further diffusion of MMC in the sclera for 1, 5, 14 and 29 min until the specimens were further processed. A central 8 mm diameter scleral disk was horizontally dissected with a kryotome at -20 degrees C. MMC concentrations of six layers of 140 microm thickness were analysed by means of high-performance liquid chromatography. The MMC concentrations (microg g(-1)) of layer 1 were: 13.45+/- 5.9 (mean +/- S.D. at 2 min diffusion time), 7.6+/-2.5 (6 min diffusion), 5.6+/-3.1 (15 min diffusion) and 3.6+/-1.7 (30 min diffusion). The corresponding MMC concentrations of layer 6 were: 0.61+/-0.48, 1.47 +/-0.66, 1.83+/-0.42 and 2.98+/-0.97 microg g(-1). The superficial concentration of intrascleral MMC decreased with increasing diffusion time, the deep concentrations increased. After 30 min of diffusion time, equal concentrations of MMC were found in all layers. Even with current low-dose application regimens of MMC the concentrations in the inner side of the sclera rapidly increase beyond the limits of the therapeutic range. Owing to this fast diffusion of MMC, the only means of reducing ciliary body concentrations of MMC is to reduce the dose.

Administration, Topical↗
PubMed1991

A traumatic cyst of the sclera.

The author describes a traumatic implantation cyst of the sclera which developed about two years after an injury with a knife, which caused a perforating scleral wound. The wound was sutured with the operating microscope. The possible mechanisms of the development of this cyst are discussed. Ophthalmologists should still bear in mind the possibility of the development of cysts of the sclera after injuries, which are rare complication nowadays.

Adult↗
PubMed1996

Immunohistochemical studies of glycosaminoglycans in nanophthalmic sclera.

BACKGROUND: It has been observed that there may be some connection between scleral collagen changes, glycosaminoglycan (GAG) changes and nanophthalmic uveal effusion. In a previous paper we reported increased dermatan sulfate (DS) and chondroitin sulfate (CS) contents in nanophthalmos sclera using biochemical analysis. In the present work we used immunohistochemical methods to assess the GAG changes in nanophthalmos sclera. METHODS: Scleral specimens from three nanophthalmic patients and five controls were processed to immunostaining with peroxidase-antiperoxidase (PAP) methods. Monoclonal antibodies for chondroitin (Ch), chondroitin-4-sulfate (C4S), chondroitin-6-sulfate (C6S), DS and keratan sulfate (KS) were used. The specimens were observed under a light microscope. RESULTS: Nanophthalmos scleral samples exhibited strong KS staining compared with the control specimens. Both the nanophthalmos and the control samples were stained with anti-Ch, anti-C4S, anti-C6S and anti-DS antibodies to the same intensity. CONCLUSION: Our results suggest that an increased or abnormal distribution of KS may contribute to abnormalities in collagen fibers.

Adolescent↗
PubMed1995

Biochemical studies of glycosaminoglycans in nanophthalmic sclera.

BACKGROUND: Since Brockhurst reported the connection between uveal effusion in nanophthalmic eyes and their scleral alterations and treated them with vortex vein decompression or sclerectomy, many observers have found abnormal accumulation of glycosaminoglycans (GAGs) in nanophthalmic sclera. These GAG abnormalities were thought to effect the collagen changes, though it was not clear which GAGs were changed. METHODS: GAGs were isolated and their contents were determined in scleral specimens from three nanophthalmic patients and five age-matched controls, using electrophoresis and the cetylpyridinium method. RESULTS: Hyaluronic acid, dermatan sulfate and chondroitin sulfate were the major GAGs in both nanophthalmic and control samples. Nanophthalmic sclera showed 2.4-fold, 10-fold and 5.5-fold increases in hyaluronic acid, dermatan sulfate and chondroitin sulfate, respectively, compared with the controls. CONCLUSION: The results suggest that increased levels of GAGs, particularly of dermatan sulfate and chondroitin sulfate may contribute to the abnormalities of collagen fibrillogenesis and be closely involved with the pathogenesis of nanophthalmos.

Adult↗
PubMed1988

Development of the human sclera. A morphological study.

Differentiation of the sclera in human embryos and fetuses with a gestation age from 6.4 to 24.0 weeks was studied by light and electron microscopy. The developmental route was found to be anteroposterior and directed from inside outwards. Continuous cytological maturation begins anteriorly during week 7.2 with a loss of free ribosomes and polysomes and an increase in the amount of rough-surfaced endoplasmic reticulum (rER) and Golgi complex components. From the region of the future limbus, these cytodevelopmental events progress posteriorly. By week 13 there are no marked differences between anterior and posterior localization. The cytodevelopmental events directed from inside outwards were found to begin during week 7.2, with a marked increase in the addition of glycogen and lipid droplets in the choroidal half of the anterior scleral condensation and from there progressing to the outer (episcleral) half. With the beginning of week 10.9 no more differences were identified between the outer and the inner portions of the sclera. Portions of the ER denuded of ribosomes close to the plasmalemma were observed during the whole gestational period studied. The role of these structures and the involvement of the Golgi complex for the biosynthesis of collagen are discussed. In week 24, the diameter of the collagen fibrils had increased more than three times in comparison with week 6.4. Elastic microfibrils were found beginning with week 7.2, whereas the elastic deposits with central electron-translucent cores were characterized for the first time beginning with week 18.

Collagen↗
PubMed1984

Characterization of collagen from normal human sclera.

Human scleral tissue contains approximately 50% collagen by weight, consisting predominantly of type I collagen. There is little or no evidence for the presence of substantial quantities of type II, type III or other collagen types. There appears to be no difference in either collagen content or genetic type in sclera between adult and juvenile tissues or between anterior and posterior segments of the sclera, although, with increased age there is a marked increase both in the extent of glycosylation of the collagen and its resistance to solubilization by treatment with pepsin.

Adult↗
PubMed1994

Semicarbazide-sensitive amine oxidase and monoamine oxidase in rat brain microvessels, meninges, retina and eye sclera.

Monoamine oxidase-A and -B (MAO-A and MAO-B) and semicarbazide-sensitive amine oxidase (SSAO) activities were assessed in several rat micro-vascular tissues and eyes using selective substrates and inhibitors. In rat brain microvessels both MAO-A and MAO-B activities are relatively high and the levels of the two types of MAO's are comparable. Retina possesses a similar ratio of MAO-A and B but the activities are much lower. Eye sclera and meninges exhibit mainly MAO-A and MAO-B, respectively. Aorta is the only tissue where SSAO is the predominant amine oxidase. Relatively low, but significant amounts of SSAO were also detected in brain microvessels, meninges, retina and eye sclera. Methylamine was observed to be deaminated by SSAO from different tissues. The physiological and toxicological implications of amine oxidases in these tissues are discussed.

Amine Oxidase (Copper-Containing)↗
PubMed2005

Amniotic membrane as an adjunct to donor sclera in the repair of exposed glaucoma drainage devices.

PURPOSE: To describe a novel method of repairing exposed glaucoma drainage devices (GDD) using amniotic membrane transplantation (AMT) in place of conjunctiva to cover donor sclera when conjunctival closure is hampered by adjacent scarring. DESIGN: Retrospective noncomparative interventional case series. METHODS: Consecutive case series of nine GDD erosions over 5 years repaired by a double-layer technique of scleral allograft plus AMT. RESULTS: Successful repair was achieved in seven cases. One GDD plate re-eroded after pars plana vitrectomy; a second leaked from the tube entry site. CONCLUSIONS: AMT is a safe and useful conjunctival substitute to cover donor sclera in situations where conjunctival scarring might otherwise preclude successful repair.

Adolescent↗
PubMedDate not supplied

Mobility of hydroxyapatite orbital implant covered with autologous sclera.

PURPOSE: To evaluate the mobility of a hydroxyapatite implant covered with autologous sclera from the enucleated globes of patients with severe atrophy of the eyeball or eyelid retraction. METHODS: This implant was used in seven patients with phthisis bulbi. We measured the movement of the implant by photographic analysis of the anterior orbit and by using a strain gauge. RESULTS: At 1-3 years after surgery, neither infection nor prolapse of the implant had occurred in any of the patients. The implant remained stable in the orbit; the extraocular muscles sutured to the sclera of the implant were functioning satisfactorily, and the implants showed great conjugate mobility to the ocular movement of the healthy eye. On photographic analysis of the anterior orbit, the adducting efficiency of the implant was 92.6 +/- 3.3%; the abducting efficiency was 85.9 +/- 5.4%; the supraducting efficiency was 84.9 +/- 5.6%, and the infraducting efficiency was 90.9 +/- 3.9%. The mean tugging weight, as determined using a strain gauge, was 344.2 +/- 29.2 g for adduction, and 327.6 +/- 33.4 g for abduction. These values corresponded to 90.4 +/- 4.4% and 89.5 +/- 5.3% of the respective movements of the healthy eye. CONCLUSIONS: Fitting an artificial eye to the peg of this implant did not greatly impair the movement of the implant, and its mobility was greater than that of the artificial eye of the controls in which a semi-integrated magnetic implant, previously available, had been used. This new technique makes it possible to wear an artificial eye earlier than with other prosthetic procedures.

Adult↗
PubMed1981

The use and fate of fascia lata and sclera in ophthalmic plastic and reconstructive surgery.

The introduction and use of newer surgical materials, better surgical instruments, finer suture materials, and improved optical equipment have allowed us to advance certain techniques in ophthalmic surgery and ophthalmic plastic surgery. In oculoplastic surgery, fascia lata and sclera are but a few of these materials used with greater frequency. In this paper, a number of techniques are described depicting the use of fascia lata and sclera. A histologic study of these materials after variable periods of implantation is presented.

Adolescent↗
PubMed1981

The use of sclera in the treatment of dysthyroid eyelid retraction.

The use of sclera for correcting dysthyroid lid retraction is described. Forty-three procedures on 14 patients are reviewed. Of these 43 procedures, 18 were for upper eyelid retraction, and 25 were for lower eyelid retraction. A tapered graft, larger temporally, was used for the upper eyelid. An eliptical graft of uniform vertical height was used for lower eyelid. Moderately predictable results were obtained; 66% of patients were corrected to within 1 mm of desired positions after the first operative procedure. Only 13% of patients required additional surgery. When secondary procedures were required, the eyelids were corrected to the desired location. Complications were minimal. Sclera proved to be an excellent graft material for dysthyroid eyelid retraction.

Adult↗
PubMed1987

[A new operation to strengthen the sclera in high myopia and its results].

The present paper communicates the technique and results of a simple operation, involving little risk of trauma, for strengthening the sclera in highly myopic children and adults. The posterior lateral part of the sclera, which offers the least resistance to deformation, is strengthened. The progression of myopia was halted in 97% of the cases thus treated, with postoperative complications occurring in only one case.

Adolescent↗
PubMed1983

[Results of sclera-laminating goniotrephination in neovascular glaucoma].

Sclera-laminating goniotrepanation is a modification of the Elliot-Fronimopoulos operation. In this procedure the scleral flap is removed, so that a shallow depression is formed in the sclera; this helps to prevent an ectatic bleb. No cicatrization of the trephine hole was observed in the authors' cases. The modification is only used by them in glaucoma cases with poor prognosis. Forty-six patients, 39 of whom were suffering from neovascular glaucoma associated with occlusion of the central retinal vein or diabetic retinopathy, underwent the operation and the results were followed up. As far as regulation of intraocular pressure and elimination of pain are concerned, the results were encouraging. Severe hemorrhage into the anterior chamber without spontaneous absorption only occurred in 2 cases.

Adult↗
PubMed1997

Compensation for spectacle lenses involves changes in proteoglycan synthesis in both the sclera and choroid.

PURPOSE: It has been demonstrated that chick eye growth compensates for defocus imposed by spectacle lenses: the eye elongates in response to hyperopic defocus imposed by negative lenses and slows its elongation in response to myopic defocus imposed by positive lenses. We ask whether the synthesis of scleral extracellular matrix, specifically glycosaminoglycans, changes in parallel with the changes in ocular elongation. In addition, there is a choroidal component to compensation for spectacle lenses; the choroid thickens in response to myopic defocus and thins in response to hyperopic defocus. We ask whether choroidal glycosaminoglycan synthesis changes in parallel with changes in choroidal thickness. METHODS: Chicks wore either a +15 diopter (D) or -15 D spectacle lens over one eye, or they wore one lens of each power over each eye for 5 days. At the end of this period, we measured refractive errors and ocular dimensions by refractometry and A-scan ultrasonography, respectively. Pieces of the scleras and choroids from these eyes were put into culture and the synthesis of glycosaminoglycans was assessed by measuring the incorporation of radioactive inorganic sulfur. RESULTS: We here report that the compensatory modulation of the length of the eye involves changes in the synthesis of glycosaminoglycans in the sclera, with synthesis increasing in eyes wearing -15 D spectacles lenses and decreasing in eyes wearing +15 D lenses. In addition, changes in the synthesis of glycosaminoglycans in the choroid are correlated with changes in choroidal thickness: eyes wearing +15 D lenses develop thicker choroids and these choroids synthesize more glycosaminoglycans than choroids from eyes wearing -15 D lenses. CONCLUSIONS: Changes in scleral glycosaminoglycan synthesis accompany lens-induced changes in the length of the eye. Furthermore, changes in the thickness of the choroid are also associated with changes in the synthesis of glycosaminoglycans. These results are consistent with the regulation of the growth of the eye being bidirectional, and with the retina being able to sense the sign of defocus.

Adaptation, Physiological↗
PubMed2001

Comparison of refractive state and circumferential morphology of retina, choroid, and sclera in chick models of experimentally induced ametropia.

PURPOSE: Simultaneous comparisons of the circumferential morphological tissue profiles and final refractions from form-deprivation myopia (FDM), defocus-induced myopia (DIM), and defocus-induced hyperopia (DIH) models of ametropia have been made to test the hypothesis that changes in the thickness profiles of the three coats of the eye, and particularly that of the choroid, can be predicted from the degree of induced refractive error. METHODS: Hatchling chickens (n = 23) were raised for 2 weeks wearing either a monocular translucent diffuser (FDM, n = 8), monocular -10.00 D lens goggle (DIM, n = 7), monocular +10.00 D lens goggle (DIH, n = 7), or nothing (Norm, n = 1). All animals were refracted using retinoscopy and were then sacrificed, and whole eyes were processed for scanning electron microscopy. Retinal, choroidal, and cartilaginous sclera (CS) thickness measurements were made from photographic collages of the entire circumference of the globe. Of the 23 chickens, complete morphological profile data were available for both eyes of 10 animals (nine treated and one normal). The contralateral fellow eyes (FEyes) of all nine experimental chickens were used as experimental controls as paired comparisons for statistical analyses. RESULTS: Morphological profiles of control and experimental eyes revealed significant systematic regional variations in tissue thickness. This variation was related to nasal or temporal eccentricity with the nasal side generally thinner than the temporal. Retinal, choroidal, and CS tissue from FDM and DIM eyes showed very similar anatomical responses despite significantly different degrees of refractive change. DIH eyes showed significant increases in choroidal thickness but none in retinal or CS thickness. Analysis of fellow control eyes indicated that in both myopia models (FDM and DIM), significant changes in all tissues of the untreated fellow eyes occur whereas only the choroid of the fellow eye was affected in the hyperopic (DIH) model. CONCLUSIONS: The morphological similarity observed in the circumferential profiles of the retina, choroid, and cartilaginous sclera of the FDM and DIM eyes despite approximately 20 D difference in final refraction suggests that choroidal thickness is not a good predictor of final refractive error across models. Similarly, the final refractive difference of approximately 20 D between the DIM and the DIH eyes did not receive a major contribution from the final difference in choroidal thickness (with its implied effect on vitreous chamber length).

Animals↗
PubMed1982

Use of sclera in tympanic membrane reconstruction.

Because of its high density, high tensile strength, and low antigenicity, sclera appears to be an appropriate grafting material for tympanic membrane reconstruction. I have used preserved donor sclera in 100 such cases over a three-year period with an overall success rate for complete closure of the perforation of 96%. Most of the procedures were done without hospitalization. The adults had local anesthesia; the children, general.

Adult↗
PubMedDate not supplied

Complications of sclera-covered enucleation implants.

PURPOSE: To determine the incidence of complications associated with the use of donor human sclera to cover porous and nonporous enucleation implants. METHODS: A retrospective case series of 207 patients receiving donor scleral-covered implants during a standardized enucleation procedure. RESULTS: There was a single case of exposure among the 112 patients (0.9%) receiving nonporous implants. None of the 95 porous implants (0%) demonstrated primary exposure. Conditions leading to the removal of 3 of the 207 (1.4%) implants included primary exposure (n = 1), secondary exposure after peg insertion (n = 1), and postoperative pain (n = 1). Two patients (1%) required postoperative tarsorrhaphies to control chemosis. Conjunctival granulomas developed in 2 patients (1%). Asymptomatic implant rotation was observed in 31% (5/16) of patients receiving flattened porous implants. There were no cases of implant migration or prolonged inflammation related to the covering material. CONCLUSIONS: Donor sclera covering of both porous and nonporous enucleation implants appears to be a successful surgical technique associated with few serious complications. The potential benefits of this technique must be balanced by the increased cost of the wrapping material and the rare but potential risk of transmitting infectious disease.

Adolescent↗
PubMed1991

Biochemical changes in rabbit sclera following destruction of pigment epithelium.

The long-term effect of destruction of the pigment epithelium by sodium iodate on the biochemistry of rabbit sclera was studied in one group with intravenous injection of sodium iodate, and in a second group with injection of sodium iodate into the right eye. Intravenous treatment produced a non-significant increase in the uronic acid concentration. In the second group the untreated fellow eye was microscopically intact, but was shown (as the treated eye) to alter the concentration of uronic acid in different parts of the sclera. All eyes from treated animals exhibited changes in the relative content of the various glycosaminoglycans and in the content of hydroxyproline, hydroxylysine and proline. This work indicates that the pigment epithelium may play a key role in the control mechanism of the scleral connective tissue, and this again has major implications in terms of a possible medical treatment of axial myopia.

Amino Acids↗