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Biomedical subjects

H D Cavanagh

Publications and source records attributed to H D Cavanagh.

At least 37 records · Page 2Linked to original sources
PubMed2000

Excimer laser treatment of spherical hyperopia: PRK or LASIK?

PURPOSE: To compare the efficacy and safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in the treatment of spherical hyperopia with use of the VISX STAR S2 excimer laser. METHODS: A review of 15 consecutive patients (22 eyes) receiving PRK and 22 consecutive patients (26 eyes) receiving LASIK (median follow-up, 12 months). RESULTS: Mean age was 52 +/- 7 years for patients receiving PRK and 55 +/- 9 years for patients receiving LASIK. Mean preoperative spherical equivalent was +2.25 +/- 1.16 D for PRK patients and +1.81 +/- 0.92 D for LASIK patients. Mean deviation from intended correction was -0.82 +/- 0.89 D after PRK and +0.19 +/- 0.47 D after LASIK at 1 month (P < .01); +0.16 D +/- 0.37 D after PRK and +0.29 +/- 0.51 D after LASIK at 6 months (P = .906); +0.20 +/- 0.35 D after PRK and +0.37 +/- 0.44 D after LASIK at 1 year (P = .301). At 1 year, 83.3% of PRK eyes and 61.5% of hyperopic LASIK eyes were within +/- 0.50 D of intended correction (P = 1.0). At 1 year, all eyes in both groups had acuity of 20/40 or better uncorrected, and 47.1% of PRK eyes and 54.5% of LASIK eyes had acuity of 20/20 or better uncorrected (P = 1.0). At last follow-up (minimum, 6 months), 2 eyes in each group had lost 2 lines of best spectacle-correct visual acuity, but none had lost more than 2 lines. All PRK patients experienced significant postoperative pain that required systemic medication. LASIK patients had only minor, transient discomfort. CONCLUSION: LASIK and PRK are of comparable efficacy and safety. However, PRK was associated with significant post-operative pain, an initial and temporary myopic overshoot peaking at 1 month, and stability not occurring before 6 months. LASIK was less painful and was associated with more rapid stability (at 1 month) and a trend toward better uncorrected visual acuity, although not statistically significant.

Female↗
PubMed1999

Quantitative measurement of acute corneal injury in rabbits with surfactants of different type and irritancy.

We have hypothesized that differences in ocular irritancy are related to differences in extent of initial injury and that, regardless of the processes leading to tissue damage, extent of injury is the primary factor that determines the final outcome of ocular irritation. In previous in vivo confocal microscopic (CM) studies we identified quantifiable differences in the extent of corneal injury occurring with four surfactants (three anionic, one cationic) known to cause different levels of ocular irritation and demonstrated that extent of initial corneal injury was related to the magnitude of cell death. The purpose of this study was to assess the applicability of this hypothesis to a broad sampling of surfactants. Specifically, initial corneal changes induced by seven different surfactants (one anionic, three cationic, three nonionic) were measured by in vivo CM and cell death was measured by an ex vivo live/dead assay. The right eye of each rabbit was treated by placing 10 microl of a surfactant directly on the cornea. Eyes were examined macroscopically and scored for irritation at 3 h and 1 day. At 3 h and 1 day, in vivo CM was used to examine the corneas and quantitate epithelial cell size, epithelial thickness, corneal thickness, and depth of stromal injury. At 3 h and/or at 1 day, corneas were removed and excised regions were placed in culture media containing 2 microM calcein AM and 4 microM ethidium homodimer. Using laser scanning CM, the number of dead epithelial and/or stromal cells in a 300 x 300 x 170-microm3 (xyz) volume of the cornea was determined. In vivo CM and live/dead assay findings revealed three surfactants to affect only the epithelium, three surfactants to affect the epithelium and superficial stroma, and one surfactant to affect the epithelium and deep stroma. Extent of initial corneal injury reflected level of ocular irritation, and magnitude of cell death was related to the extent of initial corneal injury. These findings are consistent with those for known slight, mild, and moderate to severe irritants, respectively. They suggest that our hypothesis is broadly applicable to surfactants. Additionally, we believe these surfactants should be included as part of a new "gold standard" for use in developing and validating in vitro tests to replace the use of animals in ocular irritancy testing.

Animals↗
PubMed1999

Exertion of tractional force requires the coordinated up-regulation of cell contractility and adhesion.

Although it is understood that cells exert mechanical forces on the extracellular matrix to promote structural organization, the exact mechanism of force transduction is not clearly understood. Using an in vitro force measurement assay, we evaluated two opposing conditions that inhibit or promote matrix organization by fibroblasts: serum deprivation and lysophosphatidic acid stimulation. Under serum deprivation, in spite of significant cell spreading and pseudopodial motility, rabbit corneal fibroblasts generated little or no force on the matrix within 2 h of observation. Lysophosphatidic acid stimulation of serum-starved cells caused dramatic cell contraction (within 2 min), which correlated temporally with a rapid increase in the tractional force generation on the matrix (0.52 x 10(-7) - 1.9 x 10(-7) N; n = 7 experiments). No cell translocation was observed during the period of force generation in response to lysophosphatidic acid-stimulation. These findings, taken together with a concomitant up-regulation of stress fibers in lysophosphatidic acid stimulated fibroblasts, indicate that contractility of non-motile cells involved in forming stress fibers and strong cell-matrix adhesion is the principal force-generating mechanism involved in matrix organization.

Actins↗
PubMed1999

Corneal stromal wound healing in refractive surgery: the role of myofibroblasts.

While laser and incisional refractive surgery offer the promise to correct visual refractive errors permanently and predictably, variability and complications continue to hinder wide-spread acceptance. To explain variations, recent studies have focused on the role of corneal wound healing in modulating refractive outcomes. As our understanding of the corneal response to refractive surgery broadens, it has become apparent that the response of one cell, the corneal stromal keratocyte, plays a pivotal role in defining the results of refractive surgery. Studies reviewed herein demonstrate that injury-induced activation and transformation of keratocytes to myofibroblasts control the deposition and organization of extracellular matrix in corneal wounds. Myofibroblasts establish an interconnected meshwork of cells and extracellular matrix that deposits new matrix and contracts wounds using a novel and unexpected "shoe-string-like" mechanism. Transformation of keratocytes to myofibroblasts is induced in culture by transforming growth factor beta (TGFbeta) and blocked in vivo by antibodies to TGFbeta. Overall, myofibroblast appearance in corneal wounds is associated with wound contraction and regression following incisional keratotomy and the development of "haze" or increased scattered light following laser photorefractive keratectomy (PRK). By contrast, absence of myofibroblasts is associated with continued widening of wound gape and progressive corneal flattening after incisional procedures. Based on these studies, we have arrived at the inescapable conclusion that a better understanding of the cellular and molecular biology of this one cell is required if refractive surgery is ever to achieve predictable and safe refractive results.

Animals↗
PubMed1999

The spatial organization of apical junctional complex-associated proteins in feline and human corneal endothelium.

PURPOSE: Previous studies suggest that proteins associated with the apical junctional complex (AJC) play essential roles in the development, maintenance and regulation of barrier function in transport epithelium and vascular endothelium. The goal of this study is to identify and determine the spatial organization of several major AJC-associated proteins in normal human and feline corneal endothelium. METHODS: Fresh corneal tissue was obtained from 4 recipient buttons removed during penetrating keratoplasty (two from keratoconus patients, and two from patients with post-traumatic stromal scarring) as well as from 16 cat eyes. En bloc double- and triple-labeling of corneas was performed using phalloidin, and mouse, rat or rabbit antibodies to ZO-1, occludin, pan-cadherin, alpha-catenin, beta-catenin and plakoglobin (gamma-catenin). The 3-D localization of the proteins was then determined in situ using laser confocal microscopy. RESULTS: Similar staining patterns were obtained for the corneal endothelium of normal cat corneas and fresh human buttons. Apically, f-actin was arranged into dense peripheral bands (DPB) in individual cells that were separated from those in adjacent cells. Diffuse phalloidin staining also extended from the DPB into the cytoplasm apically. Although weaker, phalloidin staining also appeared to be associated with the basolateral cell borders. The adherens junction protein, cadherin, formed a thin pericellular band at the apical cell junctions between the DPB. In addition, cadherin staining also appeared to extend along the basolateral cell borders in a convoluted pattern. Staining for alpha-catenin, beta-catenin and plakoglobin each showed a nearly identical organization as cadherin. ZO-1 formed a single apical band that was localized between the DPB; however, no basolateral ZO-1 staining was detected. Interestingly, the distribution of ZO-1 was discontinuous around the cell, with the largest gaps occurring at the Y-junctions between adjacent endothelial cells. Positive staining for occludin was not detected in either human or feline corneal endothelium. CONCLUSIONS: The composition and organization of the AJC of corneal endothelium appears to be different from that of classical transport epithelia; these findings may be related to functional differences between these two cell types.

Adult↗
PubMed1999

Changes in corneal endothelial apical junctional protein organization after corneal cold storage.

PURPOSE: Understanding the mechanisms regulating corneal endothelial permeability during storage and recovery is of critical importance both to improving Eye Banking practices and preventing corneal transplant failure. The goal of this study was to determine the effects of cold storage on the organization of apical junctional complex (AJC) proteins and their relationship to F-actin in corneal endothelium. METHODS: Immunostaining using antibodies to the AJC proteins, ZO-1, cadherin, and alpha- and beta-catenin was performed on 16 eye bank corneas and four cat corneas after 2-8 days of storage at 4 degrees C in Optisol-GS, and compared with fresh corneas. The 3-D in situ localization of the AJC proteins was then determined by using laser confocal microscopy. AJC organization also was assessed after stored human corneas were further incubated at 37 degrees C in Optisol-GS or in serum-free media. RESULTS: In normal human and cat corneas, F-actin was organized into dense peripheral bands (DPBs) along the apical cell border. The tight-junction protein, ZO-1, and the adherens junction proteins, cadherin and alpha- and beta-catenin, each formed a uniquely discontinuous hexagonal apical band with the largest gaps occurring at the Y-junctions between adjacent endothelial cells. In stored eye bank and cat corneas, cells lost their normal hexagonal F-actin staining pattern and appeared rounded and distorted, with increased cytoplasmic staining and incomplete and condensed DPBs. Similar distortions were observed in the apical bands of cadherin, catenin, and ZO-1 staining between endothelial cells. Gaps in staining at the endothelial Y-junctions were significantly enlarged; corresponding gaps also were observed with phalloidin staining. These changes were reversed after overnight incubation at 37 degrees C in either serum-free media or Optisol-GS. Quantitative analysis demonstrated a significant increase in the size of the Y-junctional gaps (p < 0.0001) after cold storage of cat corneas as compared with fresh corneas. CONCLUSION: These results suggest that disruption of the F-actin cytoskeleton and AJC may explain, in part, the loss of function (corneal swelling) after prolonged cold storage.

Animals↗
PubMed1999

Short-term hypoxia downregulates epithelial cell desquamation in vivo, but does not increase Pseudomonas aeruginosa adherence to exfoliated human corneal epithelial cells.

PURPOSE: This study evaluates the effect of hypoxic and hypercapnic stress on bacterial adherence to surface corneal epithelial cells, as well as tear LDH levels, surface cell desquamation, and corneal swelling in normal human subjects. METHODS: Sixteen eyes of eight human volunteers were successively exposed to three gas mixtures (air, 100% N2, 95% N2-5% CO2) through tightly fitted goggles for six hours at two-week intervals. Exfoliated epithelial cells were collected and counted using a modified corneal irrigation chamber. Bacterial binding was determined by measuring Pseudomonas aeruginosa (PA) adherence to exfoliated corneal epithelial cells. The effects of hypoxic or hypercapnic stress on the corneal surface were also assessed by tear LDH measurement, and quantification of surface epithelial cell size and epithelial and stromal thickness were determined by in vivo confocal microscopy. RESULTS: Short-term precorneal hypoxia significantly decreased corneal epithelial cell desquamation. Both short-term hypoxia alone and combined with hypercapnia induced significant corneal stromal swelling (7 to 8%) but did not significantly enhance PA adherence to exfoliated human corneal epithelial cells. CONCLUSIONS: This study demonstrates, for the first time, that short-term precorneal hypoxia downregulates corneal epithelial cell desquamation in humans. These results also demonstrate that short-term hypoxia alone or combined with hypercapnia does not significantly increase PA adherence to exfoliated epithelial cells from the human cornea. The results reveal that either longer hypoxic exposure or other interactive factor(s), including but not limited to the mechanical effect of the contact lens itself, may be required for promotion of increased epithelial cell-PA binding following lens wear in humans.

Adult↗
PubMed1999

The relationship between contact lens oxygen permeability and binding of Pseudomonas aeruginosa to human corneal epithelial cells after overnight and extended wear.

PURPOSE: We designed a 3-year, prospective, randomized, masked clinical trial to evaluate the relationship of contact lens oxygen transmissibility and bacterial adherence to exfoliated surface epithelial cells in human overnight and extended lens wearers in a single center; corneal cell desquamation rate, surface epithelial cell size, and tear lactate dehydrogenase (LDH) levels were also determined concurrently. METHODS: One hundred nine human volunteers were successfully fit with test lenses prospectively and completed this study. Seven soft and three rigid gas permeable (RGP) lenses with stratified oxygen transmissibility were evaluated. After one week adaptation to daily wear, patients continually wore test lenses bilaterally for three months on a six nights wear, one night off basis. Before and after 24 hour, 1 month, and three months extended contact lens wear, exfoliated surface epithelial cells were collected using a modified corneal irrigation chamber. Bacterial binding was determined by measuring Pseudomonas aeruginosa (PA) adherence to exfoliated corneal epithelial cells. The number of exfoliated cells with adherent bacteria were counted using fluorescence microscopy. The effects of contact lens wear on the corneal surface were further assessed by alterations in tear LDH, and by surface epithelial cell size and epithelial thickness using in vivo tandem scanning confocal microscopy (TSCM). Baseline values of outcome measures served as controls for individual patients; a concurrent group of controls were also followed to monitor seasonal or possible individual fluctuations. RESULTS: Quantitative evidence demonstrated that lens physical oxygen transmissibility properties and not lens type significantly correlated inversely with binding of PA to human exfoliated corneal epithelial cells after overnight and extended wear (R=0.258, P=0.0084); there was a significant decrease in surface epithelial cell desquamation and a significant increase in surface cell size following wear for all test lenses (P<0.05). Epithelial thinning was also observed following lens wear (P<0.05). CONCLUSIONS: These results establish for the first time a significant correlation between contact lens-induced increases in epithelial PA binding and lens oxygen transmissibility in humans. New ultra-oxygen permeable test lenses did not appear to increase bacterial binding over individual control levels; all test lenses suppressed surface epithelial cell shedding. Taken together, these findings suggest that a new generation of contact lenses constructed from ultra-transmissible oxygen materials may offer a significant potential advance in safety for extended wear.

Adult↗
PubMed1999

Transforming growth factor(beta)-mediated corneal myofibroblast differentiation requires actin and fibronectin assembly.

PURPOSE: Recent studies indicate that transforming growth factor (TGF)beta is a potent inducer of corneal myofibroblast differentiation and expression of smooth muscle-specific, alpha-actin (alpha-SMA). Although TGFbeta is known to enhance synthesis of extracellular matrix proteins and receptors, little is known about how it modulates the expression of smooth muscle proteins in nonmuscle cells. The purpose of this study was to identify the role of Arg-Gly-Asp (RGD)-dependent tyrosine phosphorylation in regulating alpha-SMA gene expression and ultimately myofibroblast development. METHODS: Because cell culture in serum-containing media mimics myofibroblast transformation, all experiments were performed on freshly isolated rabbit keratocytes plated in defined, serum-free media. Cells were exposed to TGFbeta (1 ng/ml), Gly-Arg-Gly-Asp-D-Ser-Pro (GRGDdSP, 50 microM), Gly-Arg-AL-Asp-Ser-Pro (GRADSP; 100 microM), or herbimycin A (0.1-10 nM) at 24 hours (sparse) or 7 days (confluent). Cells were evaluated by immunocytochemistry and proteins and RNA collected for western and northern blot analyses using antibodies specific for alpha-SMA, fibronectin, focal adhesion proteins, and phosphotyrosine (clones 4G10 and PY20); and probes directed against rabbit alpha-SMA. All experiments were repeated at least three times. RESULTS: Keratocytes exposed to TGFbeta showed expression of alpha-SMA that coincided with the intracellular reorganization of the actin cytoskeleton and the extracellular assembly of fibronectin fibrils. Addition of RGD containing but not control peptides blocked the organization of intracellular actin, extracellular fibronectin, and alpha-SMA protein and mRNA. Immunoprecipitation of cell proteins with 4G10 or PY20 identified the TGFbeta-associated tyrosine phosphorylation of paxillin, pp125fak, p130, PLCgamma, and tensin, which was blocked by addition of GRGDdSP. Addition of herbimycin A to keratocytes exposed to TGFbeta showed a dose-dependent loss of alpha-SMA protein and mRNA which correlated with loss of tyrosine phosphorylation, absence of actin reorganization, and fibronectin assembly. CONCLUSIONS: The data suggest that TGFbeta-mediated alpha-SMA gene expression leading to myofibroblast transformation may involve an RGD-dependent phosphotyrosine signal transduction pathway.

Actins↗
PubMed1999

The effect of rigid gas permeable contact lens wear on proliferation of rabbit corneal and conjunctival epithelial cells.

PURPOSE: To study the effect of rigid contact lens oxygen transmissibility on cell proliferation of the corneal, limbal, and conjunctival epithelium in vivo following 2 days of extended wear in the rabbit model. METHODS: Fourteen adult New Zealand White rabbits were divided equally into two groups. Each group was assigned to one of two test rigid gas permeable (RGP) contact lenses (Dk/Ltotal = 10 and 97) with uniform thickness (0.15 mm) and diameter (14.0 mm). One eye of each rabbit randomly received a contact lens for two days (48 hrs) extended wear, and the fellow eye was used as a control. Rabbits were injected intravenously with 5-bromo-2-deoxyuridine (200 mg/kg) in sterile phosphate buffered saline (pH 7.4) 24 hours before being killed. Corneas with a limbal rim of episclera and overlying conjunctiva were fixed in situ and excised. Nuclei labeled with BrdU were detected with a monoclonal anti-BrdU antibody and an FITC-conjugated secondary antibody. Digital images were collected and BrdU-labeled nuclei of whole-mount corneas were counted from superior limbus to inferior limbus using epifluorescence microscopy. RESULTS: Twenty-four hours after intravenous injection of BrdU, labeled nuclei were confined to and appeared as pairs in the basal epithelial layer. The density of BrdU-labeled nuclei were found to be 258 +/- 42, 167 +/- 43, 372 +/- 64, and 310 +/- 46 (pairs/mm2, mean +/- SD, n = 14) in normal controls for adjacent conjunctiva, limbus, peripheral cornea, and central cornea, respectively. By contrast,there was significant 81.35% (low Dk)and 22.46% (ultra-high Dk) suppression of cell proliferation in the central cornea after two days lens wear (n = 7). In addition, significant increases in the labeling of limbal and conjunctival epithelium were also noted. CONCLUSIONS: Significantly less BrdU labeling of epithelial cells at the normal rabbit limbus was noted as compared to the peripheral and central cornea (P < 0.05) and is consistent with the presence of slow-cycling limbal basal cells and the limbal stem cell theory; however, this is the first report of up-regulation of limbal cell proliferation induced by contact lens wear. This study also revealed, for the first time, that short-term extended wear of RGP lenses inhibits central corneal epithelial cell proliferation. This effect was significantly more pronounced for a low-oxygen vs. a hyper-oxygen transmissible test lens. This data also suggests that corneal epithelial layer thinning seen following extended contact lens wear may be explained, in part, by suppression of basal epithelial cell proliferation. Further study is clearly necessary to validate and extend these preliminary findings.

Animals↗
PubMed1999

Risk of prion disease transmission from ocular donor tissue transplantation.

PURPOSE: Recent new reports of possible iatrogenic transmission of Creutzfeldt-Jakob disease (CJD) in Europe have prompted renewed scrutiny of current Eye Bank Association of America criteria for evaluation of potential corneal donors in this country. A prior study evaluated the risk of CJD occurring in U.S. corneal donors by using data to 1994. This report updates these data, analyses the risk by using data to 1997, and predicts potential risk into the next decade. METHODS: EBAA data inclusive through 1997 were reviewed and correlated with incidence figures for CJD in the United States as provided by the Communicable Disease Center in Atlanta. RESULTS: The annual incidence of CJD has remained stable at 1 case per million population. Thus approximately 270 new cases of CJD would be expected to occur each year in the United States. From this, the calculated risk of a prion-infected corneal donor appearing in the donor pool is 0.045 cases per year. If the data are corrected for age (90% of CJD patients are older than 60 years) and for possible infected but asymptomatic CJD patients (prevalence, 70 cases per million), at worst, 2.12 cases per year would appear for potential corneal donation (0.005% of all donors). Whereas donors completely without any neurologic symptoms cannot be screened by using any currently available laboratory method, those with a characteristic quadrate clinical prodrome including cognitive changes, speech abnormalities, cerebellar findings, and myoclonus could all be potentially excluded by using tightened medical record and historical screening criteria. Although no cases of bovine spongiform encephalopathy (mad-cow disease) or new variant CJD have been reported in the United States, if such should occur, only 4.2 cases of CJD would be expected in potential donors each year (0.009% of all donors). Tightening of exclusionary queries would significantly reduce the risk of even this number of patients appearing for corneal donation. CONCLUSIONS: Historical queries of potential corneal donors should be tightened to assure exclusion of donors with early neurologic alterations. Any patient undergoing autopsy for evaluation of possible central nervous system (CNS) disease should be absolutely excluded. With this approach, the risk of inclusion of CJD-infected transplant tissues derived from ocular sources is very small, and all previously reported cases would have been prospectively excluded from surgical use. Clearly, the benefits of corneal transplantation in the overall population continue significantly to outweigh the risks of transmission of prion disease.

Animals↗
PubMed1999

Labeling of cycling corneal endothelial cells during healing with a monoclonal antibody to the Ki67 antigen (MIB-1).

PURPOSE: To assess the efficacy of labeling actively cycling corneal endothelial cells by using a monoclonal antibody to the Ki67 antigen (MIB-1) and to determine what changes in f-actin and ZO-1 organization are associated with entry into the cell cycle during wound healing under different culture conditions. METHODS: Three corneal buttons (6 mm diameter) were punched from each cornea of 15 cats. After a mechanical scrape injury (2 mm diameter) was made, buttons were cultured for 24, 48, or 72 h in serum-free media (SFM), SFM plus 10% fetal calf serum, or SFM plus basic fibroblast growth factor (bFGF). Buttons were single and double labeled by using phalloidin, anti-ZO-1, and MIB-1. Counts of Ki67-positive cells were used to determine the number of actively cycling endothelial cells. RESULTS: After culture in SFM, wounds healed by cell spreading with maintenance of normal apical f-actin and ZO-1 organization; Ki67-positive cells were detected near the leading edge in some areas. A significant increase in the number of cycling cells was measured after 48 h of culture in bFGF as compared with SFM (p<0.05); serum increased the number of cycling cells more than both SFM and bFGF (p<0.05). In all cases, positive MIB-1 staining was not observed until 48 h after injury, was limited to cells actively spreading over the wound area, and was diminished after wound closure (72 h). Double labeling demonstrated that endothelial cells exhibited a fibroblastic phenotype in some central areas of cell proliferation after culture in serum or bFGF, but, in general, apical cell border-associated f-actin and ZO-1 organization was partially maintained in most Ki67-positive cells. CONCLUSION: The data suggest that spreading corneal endothelial cells are capable of proliferating and can respond to growth factors, but that dedifferentiation or fibroblastic transformation is not required before entry into the cell cycle. Overall, the MIB-1 antibody appears to be ideally suited to the study of corneal endothelial proliferation during wound healing.

Actins↗
PubMed1998

Assessment of stress fiber orientation during healing of radial keratotomy wounds using confocal microscopy.

Radial keratotomy (RK) is a refractive surgical procedure in which partial thickness incisions are made in the cornea in order to alter its shape. Previous studies suggest that RK wounds undergo changes in wound gape in response to the ingrowth of myofibroblasts which mediate subsequent wound contraction and may modulate changes in corneal curvature seen after RK. A recent quantitative analysis of f-actin organization in full-thickness incisional wounds in the rabbit demonstrated that microfilament bundles (stress fibers) present in myofibroblasts align parallel to the long axis of the wound during wound contraction. To investigate whether the same pattern of alignment occurs after RK, a similar analysis of f-actin organization was undertaken using the cat RK model. Radial keratotomy wounds were studied from 10 to 28 days after surgery using en block staining with fluorescein isothiocyanate (FITC) phalloidin, and three-dimensional (3-D) datasets (z-series of en face optical sections) were collected using laser confocal microscopy at various regions within the wound. In addition, conventional en face sections were double-labeled using combinations of phalloidin and antibodies to fibronectin and alpha 5 beta 1 integrin. Myofibroblast ingrowth started in the bottom of the wound and progressed anteriorly. At 10 to 14 days, f-actin was predominantly distributed in long, thick bundles (stress fibers) within the wound. These fibers appeared to be randomly oriented anteriorly, but became progressively more aligned with the long axis of the wound posteriorly. At 21 days, the stress fibers were predominantly oriented parallel to the long axis of the wound at all levels. F-actin, fibronectin and integrin were coaligned at both the 14 and 21 day time points. Since the majority of wound closure occurs between 14 and 28 days after surgery, we conclude that parallel alignment of the actin filament-fibronectin-integrin assembly in the cat RK model is associated with wound contraction.

Actin Cytoskeleton↗
PubMed1998

Reliability of intraocular pressure measurements after myopic excimer photorefractive keratectomy.

OBJECTIVE: To determine the reliability of intraocular pressure (IOP) measurements by Goldmann applanation tonometry and pneumotonometry in eyes treated with excimer myopic photorefractive keratectomy (PRK). DESIGN: A prospective case series. PARTICIPANTS: Forty consecutive eyes treated with PRK were evaluated. INTERVENTION AND MAIN OUTCOME MEASURES: Central and peripheral corneal Goldmann tonometry and pneumotonometry measurements were done before surgery, at 1 week, and at 1 and 3 months after surgery. RESULTS: The IOP by Goldmann tonometry from the central cornea was significantly lower than the peripheral IOP; however, there was no difference between IOP measured from central and peripheral corneas by pneumotonometry, which, in turn, correlated with peripheral Goldmann measurements. There was a trend, but not a statistically significant correlation, between the spherical equivalent of the treatment and the amount of decrease in central Goldmann IOP. CONCLUSIONS: Pneumotonometry measures the IOP reliably after PRK from all parts of the cornea, whereas central Goldmann tonometry underestimates the IOP by 2.40+/-1.23 mmHg.

Administration, Topical↗