Transparency, swelling and scarring in the corneal stroma

Meek, Keith Michael Andrew; Leonard, D.W.; Connon, Che J.; Dennis, Sally; Khan, Shukria

doi:10.1038/sj.eye.6700574

Cited by 198 publications

(146 citation statements)

References 45 publications

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“…It has been demonstrated that corneal edema after phacoemulsification has been associated with a relatively lower IOP by Goldmann applanation tonometry because of the reduction of corneal hysteresis and alterations of the stromal lamellar architecture. [18][19][20] Another possibility is the use of Alphagan P immediately after SLT but as only a single drop was instilled, it is unlikely to cause a significant drop in day 1 IOP. Thus, the IOP at 1 month post SLT may more accurately reflect the true change in IOP as a result of the SLT procedure.…”

Section: Discussionmentioning

confidence: 99%

Corneal changes after a single session of selective laser trabeculoplasty for open-angle glaucoma

Lee

Chan

Chang

et al. 2013

Eye

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Purpose To investigate the changes in endothelial cell count, central corneal thickness (CCT), and refractive error after a session of selective laser trabeculoplasty (SLT) for open angle glaucoma (OAG). Methods This prospective cohort study recruited 111 eyes of 66 consecutive subjects with OAG. Subjects received SLT to 3601 of the trabecular meshwork. Endothelial cell count, CCT, and spherical equivalent were measured at baseline before SLT as well as at 1 week and 1 month post SLT. A repeated measure nested ANOVA with Tukey's multiple comparison test was performed to compare the outcome measures before and after SLT. Results In 111 eyes of 66 subjects, the mean number of laser applications per treatment was 166.9 ± 41.4 with a mean energy level of 1.0 ± 0.07 mJ. The mean endothelial cell count decreased significantly from 2465.0±334.0 cells/mm 2 at baseline to 2355.0±387.0 cells/mm 2 at 1 week (P ¼ 0.0004) but increased to baseline levels at 1 month post SLT (2424.0 ± 379.4 cells/mm 2 , P ¼ 0.3). The CCT, which decreased from a baseline of 549.4 ± 37.6 to 543.9 ± 40.2 mm at 1 week post SLT (P ¼ 0.02), also returned to the baseline level by 1 month (P ¼ 0.2). The spherical equivalent was static from baseline. A positive correlation was found between total laser energy and CCT at 1 month post treatment (r ¼ 0.3, P ¼ 0.005). Conclusion The transient reductions in endothelial cell count and CCT following SLT returned to baseline levels 1 month after the procedure. Patients undergoing SLT should be aware of the risk of potential corneal changes.

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Section: Discussionmentioning

confidence: 99%

Corneal changes after a single session of selective laser trabeculoplasty for open-angle glaucoma

Lee

Chan

Chang

et al. 2013

Eye

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“…For each cornea, measurements were taken for 146 angular positions ranging from À1:2 to þ85 outside the cornea cell, corresponding to the À0: 9 and 48:6…”

Section: Resultsmentioning

confidence: 99%

“…The small amount of scattered light produced by this tissue has in particular been extensively researched in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. All previous theories explaining corneal transparency [21][22][23][24][25][26][27] have focused on light propagation in the stromal extracellular matrix.…”

Section: Introductionmentioning

confidence: 99%

Measurement of correlation between transmission and scattering during wound healing in hen corneas

Mar

Martínez-García

Blanco–Mezquita

et al. 2009

Journal of Modern Optics

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The aim of this work is to provide experimental data for corneal transparency and scattering to help create a more complete model of corneal transparency. The scattered light in 96 healing hen corneas was measured for three wavelengths by a scatterometer constructed in the Optics Laboratory (The University of Valladolid, Spain). With the help of mirrors and beamsplitters, the light from the three lasers is directed toward the cell containing the sample to be measured. The measured scattered light varies between six orders of magnitude. Corneal transmissivity, mean cosine of a scattering angle, and angular distribution of scattered light were all computed. The total transmitted light remained practically constant over a wide range of light values transmitted in a forward direction (direct transmissivity). The value of the mean cosine of the scattering direction is very close to the unit (g 4 0:98), even in corneas with high opacities. The behavior of g indicates that even damaged corneas evidence extremely small scattering, compared to other biological tissues. The transmission reduction of each cornea is related to an increase in scattered light. In all cases, scattered light is concentrated at very small angles. This behavior is acceptable in corneas that are healthy or which evidence small lesions, but remains in corneas that are severely injured.

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“…This spacing is controlled by collagen-associated small leucine-rich proteoglycans that form glycosaminoglycan cross-links between adjacent fibrils (4). Disruption of the fibril spacing is a major cause of loss of corneal transparency in scarring and stromal pathological conditions (5). In scars, interfibrillar glycosaminoglycan cross-links are altered or eliminated, and spaces without fibrils, known as "lakes," have been identified (5).…”

Section: Hyaluronan (Ha)mentioning

confidence: 99%

“…Disruption of the fibril spacing is a major cause of loss of corneal transparency in scarring and stromal pathological conditions (5). In scars, interfibrillar glycosaminoglycan cross-links are altered or eliminated, and spaces without fibrils, known as "lakes," have been identified (5). The almost ubiquitous presence of HA in nontransparent corneas suggests a relationship between the large hydrodynamic volume occupied by HA molecules and the disruption of the stromal ultrastructure.…”

Section: Hyaluronan (Ha)mentioning

confidence: 99%

A Rapid Transient Increase in Hyaluronan Synthase-2 mRNA Initiates Secretion of Hyaluronan by Corneal Keratocytes in Response to Transforming Growth Factor β

Guo

Kanter

Funderburgh

et al. 2007

Journal of Biological Chemistry

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Keratocytes of the corneal stroma produce transparent extracellular matrix devoid of hyaluronan (HA); however, in corneal pathologies and wounds, HA is abundant. We previously showed primary keratocytes cultured under serum-free conditions to secrete matrix similar to that of normal stroma, but serum and transforming growth factor ␤ (TGF␤) induced secretion of fibrotic matrix components, including HA. This study found HA secretion by primary bovine keratocytes to increase rapidly in response to TGF␤, reaching a maximum in 12 h and then decreasing to <5% of the maximum by 48 h. Cell-free biosynthesis of HA by cell extracts also exhibited a transient peak at 12 h after TGF␤ treatment. mRNA for hyaluronan synthase enzymes HAS1 and HAS2 increased >10-and >50-fold, respectively, in 4 -6 h, decreasing to near original levels after 24 -48 h. Small interfering RNA against HAS2 inhibited the transient increase of HAS2 mRNA and completely blocked HA induction, but small interfering RNA to HAS1 had no effect on HA secretion. HAS2 mRNA was induced by a variety of mitogens, and TGF␤ acted synergistically to induce HAS2 by as much as 150-fold. In addition to HA synthesis, treatment with TGF␤ induced degradation of fluorescein-HA added to culture medium. These results show HA secretion by keratocytes to be initiated by a rapid transient increase in the HAS2 mRNA pool. The very rapid induction of HA expression in keratocytes suggests a functional role of this molecule in the fibrotic response of keratocytes to wound healing. Hyaluronan (HA)2 is a high molecular weight, nonsulfated glycosaminoglycan abundant in most tissues, where it acts as a hydrating agent and an organizer of extracellular matrix scaffolding via specific interactions with matrix proteins containing hyaluronectin domains (for review see Ref. 1). The corneal stroma, unlike most vertebrate tissues, is virtually devoid of HA. During active corneal wound healing and in corneas with various chronic pathologies, however, hyaluronan becomes abundant in the corneal stroma (2, 3).The corneal stroma maintains transparency to light by virtue of the highly organized structure of its collagenous extracellular matrix. Collagen fibrils of the stroma exhibit highly regular parallel alignment and spacing. This spacing is controlled by collagen-associated small leucine-rich proteoglycans that form glycosaminoglycan cross-links between adjacent fibrils (4). Disruption of the fibril spacing is a major cause of loss of corneal transparency in scarring and stromal pathological conditions (5). In scars, interfibrillar glycosaminoglycan cross-links are altered or eliminated, and spaces without fibrils, known as "lakes," have been identified (5). The almost ubiquitous presence of HA in nontransparent corneas suggests a relationship between the large hydrodynamic volume occupied by HA molecules and the disruption of the stromal ultrastructure. Additionally, the recent recognition of the diverse bioactivity of HA (6) raises the potential that matrix production by stromal keratocytes may...

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Transparency, swelling and scarring in the corneal stroma

Cited by 198 publications

References 45 publications

Corneal changes after a single session of selective laser trabeculoplasty for open-angle glaucoma

Corneal changes after a single session of selective laser trabeculoplasty for open-angle glaucoma

Measurement of correlation between transmission and scattering during wound healing in hen corneas

A Rapid Transient Increase in Hyaluronan Synthase-2 mRNA Initiates Secretion of Hyaluronan by Corneal Keratocytes in Response to Transforming Growth Factor β

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