Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A scalloped line of tear film thinning (corneal valance), running horizontally across the top third of the cornea, was readily seen with slit lamp, fluorescein, and blue filter in 25 patients. Careful retrospective examination of these patients revealed barely discernible map and fingerprint lines corresponding to the areas of tear film irregularity. A corneascope photograph suggests that the tear film thinning in corneal valance is caused by localized elevations of the epithelial surface. The importance of corneal valance is that it is easily seen, and makes possible the diagnosis of map-dot-fingerprint corneal dystrophy in cases that might otherwise be misdiagnosed or overlooked.
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PMID:Corneal valance: a tear film pattern in map-dot-fingerprint corneal dystrophy. 661 Nov 1

Two studies were performed to investigate dimensional stability of the cornea throughout the female menstrual cycle. In the first study, changes of corneal curvature, topography, and thickness were measured for six women for one complete menstrual cycle. Steepening of horizontal and vertical curvatures occurred at the beginning of the cycle, and flattening occurred after ovulation. Corneal thickening occurred on the second day of the cycle and around the time of ovulation, then thinning and another slight thickening on day 21. In the second study, more detailed information was sought on the timing of corneal thickness changes throughout any cycle. Corneal thickness was studied for two subjects throughout three consecutive cycles. Both subjects showed a slight decrease in thickness toward the end of the menses; thickening occurred at ovulation followed by thinning. Thickening also occurred 4 days after ovulation. Consideration of changes in urine levels of estrogen and pregnanediol suggests that rises in estrogen are accompanied by increases in corneal thickness.
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PMID:Menstrual cycle variations of corneal topography and thickness. 665 Jun 53

Fluorophotometry was used to evaluate the effect of the blinking process on tear spreading. In normal individuals, when the intensity of fluorescence was monitored over the central 1 mm of the cornea, forceful blinking was found to substantially increase tear film thickness. Weak blinking was found to decrease tear film thickness. When tear film fluorescence was monitored along different regions of the corneal vertical meridian, the tear film thickened superiorly while thinning inferiorly. It is postulated that the vertical spreading of meibomian oils is accompanied by the movement of a portion of the aqueous tear phase that thickens the superior tear film at the expense of thinning inferiorly.
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PMID:In vivo observation of tear dynamics using fluorophotometry. 670 90

Corneas of fetal and young albino rabbits were examined by light and transmission electron microscopy. In addition, DNA and hydroxyproline content were measured in developing stroma. The results were compared with similar data from healing corneas in adult rabbits and from developing corneas of other animal species. In the fetal rabbit, the prospective corneal stroma region contains an unorganized, sparse extracellular matrix until about the 13th day of gestation, when mesenchymal cells and capillaries from the hyaloid vessels move in to form the vascular pupillary membrane, endothelium, and stroma. Stromal growth is due to alteration in the density and morphology of the cell population early in development, along with a sequential thickening and thinning of the whole stroma. These events are similar to those reported in primates, but differ markedly from those reported in avian species. Normal developing cornea and healing adult cornea both involve migration of stomal fibroblasts and deposition of extracellular matrix. Stromal fibroblasts in the rabbit fetus are oriented with their long axis parallel to the corneal surface early in development compared with randomly oriented fibroblasts in the early healing wound of adult rabbit corneas. Although collagen and cell number progressively increase throughout the developmental periods studied, the ratio of cells to collagen is high initially but decreases with development. In contrast, the proportion of cells to collagen in the young scar tissue of adult cornea is low initially, indicating a marked deposition of collagen in comparison to that in the early normal developing stroma. The results suggest that the healing tissue differs from the normal fetal stroma in its coordination of cell population growth with collagen deposition and cellular organization.
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PMID:Morphogenesis of rabbit corneal stroma. 684 Oct

Histological and ultrastructural examination of the corneas of a woman presenting with marginal pellucid degeneration, treated by bilateral perforating keratoplasty, revealed obvious analogies with keratoconus. The condition of marginal pellucid degeneration is really only an excentric keratoconus. Marginal pellucid degeneration is a rare affection but it has been clinically sell defined. Many authors seem to have recognized it under various different names (cylindrical keratoconus, corneal protusion, piriform cornea). It is a pouch-shaped deformity of the cornea overlying a thinning of the linear stroma concentric to the limbus, always inferior and bilateral, perfectly transparent, non-vascularized, and without signs of corneal of conjunctival inflammation. The affection usually occurs in young adults.
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PMID:[Marginal pellucid degeneration of the cornea, or marginal keratoconus (author's transl)]. 696 44

Protein deficiency is one of the major morbid nutritional disorders of the developing world. Increased incidence of infection in a protein-deficient state is well documented in the literature. Structural alterations produced by isolated protein deficiency on the cornea are not clear hitherto. In this investigation, it has been shown that protein deficiency in rats results in thinning of the corneal epithelial cell layers and oedema of the epithelial, stromal and endothelial cells. The pathomechanisms are discussed.
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PMID:Rat cornea in experimental protein deficiency. 709 45

A 76-year-old woman had signs of endophthalmitis the third day after she underwent uneventful cataract surgery. Intravitreous antibiotics were given, but the eye was unresponsive to the therapy, and, two days later, a small scleral abscess was noted that was not connected to the cornea. Pars plana vitrectomy and appropriate antibiotic therapy were successfully used, and, eventually, the retina regained useful visual acuity. A ring of multiple scleral abscesses developed that persisted for three months, producing scleral thinning and concentric ectasia of the globe. The cornea was free of ulceration at all times. We are unaware of any published cases of Pseudomonas abscess of the sclera without corneal ulceration or scleral damage.
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PMID:Scleral abscesses and ectasia caused by Pseudomonas aeruginosa. 712 58

A family is described with corectopia, nystagmus, absent foveal reflexes, and corneal changes inherited in an autosomal dominant pattern. Other abnormalities found in this family include microcornea, Bitot's spots, and iris colobomas. Faint superficial opacities and fine superficial vessels were found in the peripheral cornea of younger family members. Older family members showed an increase in the density of the superficial opacities and areas of stromal thinning were found in the 60-year-old proband. Corneal vessels and progression centrally. Full-thickness stromal opacities and changes have been associated with familial and sporadic aniridia and iris colobomas. The present report describes similar changes in association with corectopia.
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PMID:Corectopia with nystagmus, absent foveal reflexes and corneal changes. 721 Dec 87

The feasibility of using hydrogel lenticular implants of high water content to alter the anterior corneal curvature for purposes of refractive keratoplasty has been investigated in rabbits. Lenticules (6 mm in diameter) of Permalens (Perfilcon-A) were trephined from contact lens and implanted within an intralamellar pocket in the cornea. The in vitro glucose flux across the hydrogel (0.23 mm thick) was measured at 131 +/- 7 micrograms/cm(2)/hr. For clinical comparison, non-water-permeable disks of Teflon were also implanted. The Teflon implant caused an aseptic ulcer to develop anterior and central to the implant by 9 +/- 4 days. The hydrogel lenticular implant did not cause central ulceration during the 7 month postoperative follow-up. There was a thinning and eventual erosion of the stroma anterior to the edge of the hydrogel implant, 16 +/- 7 weeks. The glycogen contents of the epithelium anterior to (1) the sham operation, i.e., lamellar pocket dissection, (2) the implanted hydrogel lenticule with or without the presence of an erosion, and (3) the control corneas were statistically from the same population. Yet there was a slight dehydration of the stroma anterior to the hydrogel implant when compared to control tissue. A thin-edged implant lenticule design should overcome the stromal thinning caused by the thick-edge implants. During the short-term follow-up, the hydrogel lenticular implant proved to be successful as a refractive keratoplasty implant material.
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PMID:Refractive keratoplasty with intrastromal hydrogel lenticular implants. 725 Dec 94

After debridement of the entire corneal epithelium, epithelial cells of conjunctival origin cover the exposed corneal surface. Four to five weeks later, these cells undergo a morphologic transformation to normal-appearing corneal epithelium. To study this transformation the entire corneal epithelium was removed from rabbits with the use of n-heptanol, after which the histologic appearance of and the number of goblet cells in the regenerated epithelium were noted. Five stages of transformation were seen. Immediately after healing, the epithelium consisted of one to two squamous cell layers with no goblet cells apparent at the light microscope level (stage 1). In the following weeks goblet cells appeared at the limbal edge of the cornea (stage 2), reached a uniform distribution across the cornea (stage 3), and subsequently receded toward the limbus (stage 4), leaving an epithelium with normal corneal morphologic appearance (stage 5). To see if there was an ongoing centripetal cell migration from the conjunctiva across the cornea after initial healing, the central corneal epithelium was isolated from the periphery by a ring of glue. Such isolation resulted in a thinning of the central epithelium and a thickening of the peripheral epithelium. These studies suggest that (1) the transformation into corneal epithelium lags behind defect closure by 4 to 5 weeks, (2) goblet cells do not initially migrate as recognizable cells, and (3) there is a continuous centripetal cell motion even after the initial defect closure is accomplished.
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PMID:Corneal re-epithelialization from the conjunctiva. 725 Dec 97


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