Inhibitory effects of topical cyclosporine A 0.05 % on immune-mediated corneal neovascularization in rabbits

Background

We aimed to study the inhibitory effects of topical cyclosporine A (CsA) 0.05 % on immune-mediated corneal neovascularization, and to compare its efficacy with those of dexamethasone 0.1 % and bevacizumab 0.5 %.

Methods

Immune-mediated corneal neovascularization was created in 36 right eyes of 36 rabbits. The rabbits were then randomized into four groups. Group I received CsA 0.05 %, Group II received dexamethasone 0.1 %, Group III received bevacizumab 0.5 %, and Group IV received isotonic saline twice a day for 14 days. The corneal surface covered with neovascular vessels was measured on the photographs. The rabbits were then sacrificed and the corneas excised. Paraffin-embedded sections were stained with hematoxylin-eosin and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay.

Results

The means of percent area of corneal neovascularization in Group I, II, III, and IV were 24.4 %, 5.9 %, 37.1 %, and 44.1 %, respectively. The inhibitory effect of CsA 0.05 % was found to be better than the effect found in the bevacizumab 0.5 % and control groups (p?=?0.03 and p?=?0.02, respectively). CsA 0.05 % was found to have significantly lesser inhibitory effects on corneal neovascularization than dexamethasone 0.1 % (p?<?0.001). Apoptotic cell density was higher in Group III and Group IV than in Group I and Group II. There was no difference between Group I and Group II in terms of apoptotic cell density (p?=?0.7).

Conclusions

Topical CsA 0.05 % was shown to have an inhibitory effect on immune-mediated corneal neovascularization in rabbits.     

Histologic findings of recipient corneas obtained via deep anterior lamellar keratoplasty

Purpose

We sought to investigate the histologic findings of recipient corneas obtained via deep anterior lamellar keratoplasty (DALK).

Methods

The histology of three recipient corneas obtained from patients during DALK was investigated. In all cases, the Descemet membrane was successfully exposed without any perforation during surgery. The isolated corneal tissue was stained with hematoxylin-eosin and periodic acid-Schiff. In two cases, the tissues were examined using a transmission electron microscope.

Results

In one cornea obtained via DALK, only the corneal stroma was observed, and the Descemet membrane was not confirmed. In another case, the recipient cornea was detached within the Descemet membrane. In the third cornea, the banded layer membrane was partially confirmed.

Conclusions

These findings suggest that the recipient corneas separated at different layers during the DALK procedure. With our surgical technique, the detachment of the Descemet membrane may occur at a mechanically weak segment. This separation site may not be between the Descemet membrane and the corneal stroma.     

Effects of the Matrix Metalloproteinase Inhibitor GM6001 on the Destruction and Alteration of Epithelial Basement Membrane During the Healing of Post-alkali Burn in Rabbit Cornea

Purpose

To examine the alteration in structure and matrix composition of epithelial basement membrane (BM) during the healing of alkali-burned rabbit cornea, and the roles of matrix metalloproteinases (MMPs) in these alterations.

Methods

The central cornea of one eye of 78 albino rabbits was exposed to 1?N NaOH for 180?s under general and topical anesthesia and allowed to heal with or without subconjunctival injection of GM6001 (an MMP inhibitor). Cryosections of affected corneas were observed by H&;E staining, immunohistochemistry for type IV collagen subtypes, or in situ zymography for detection of localization of MMP activity.

Results

Uninjured corneal epithelial BM exhibited α5 (IV)-immunoreactivity, but lacked the α1/α2-immunoreactivity of collagen IV. Epithelial BM in healing burned cornea transiently exhibited α1/α2-immunoreactivity. Examination by in situ zymography showed an upregulation of MMP activity in the regenerated central epithelium and anterior stroma of the burned corneas at days 7 and 14. GM6001 suppressed degradation of α5-containing epithelial BM in vivo and also in organ culture.

Conclusions

Epithelial BM was degraded by endogenous MMPs during healing following an alkali burn in rabbit cornea. GM6001 had an inhibitory effect on the degradation of the epithelial basement membrane in burned cornea in vivo.?Jpn J Ophthalmol 2006;50:90–95 © Japanese Ophthalmological Society 2006     

Short- and long-term corneal vascular effects of tafluprost eye drops

Background

Prostaglandin analogs are first line therapy in the treatment of glaucoma, but also display side effects during ocular inflammation. In this context, the potential side effects of prostaglandin analogs on the normally avascular cornea, the main application route for eye drops, are so far not fully defined. Therefore, the aim of this study was to evaluate the vascular effects of the prostaglandin analog tafluprost on the healthy and inflamed cornea.

Methods

For in vitro studies, blood and lymphatic endothelial cells were treated with tafluprost; cell proliferation was assessed after 48 h. For long-term in vivo studies under healthy conditions, naïve corneas of BALB/c mice were treated with tafluprost eye drops for 4 weeks. For short-term in vivo studies under inflammatory conditions, corneal inflammation was induced by suture placement; mice then received tafluprost eye drops for 1 week. Afterwards, corneas were stained with CD31 as panendothelial and LYVE-1 as lymphendothelial (and macrophage) marker.

Results

In vitro, tafluprost did not alter blood or lymphatic endothelial cell proliferation. In vivo, there was no change in limbal blood or lymphatic vessel anatomy after long-term treatment with tafluprost. Short-term treatment with tafluprost under inflammatory conditions did not influence the recruitment of LYVE-1 positive macrophages into the cornea. Moreover, treatment of inflamed corneas with tafluprost did not significantly influence corneal hem- and lymphangiogenesis.

Conclusions

Tafluprost does not affect blood and lymphatic vessel growth, neither under resting nor under inflammatory conditions. These findings suggest a safe vascular profile of tafluprost eye drops at the inflammatory neovascularized cornea.     

The Ex Vivo Eye Irritation Test (EVEIT) in evaluation of artificial tears: Purite?-preserved versus unpreserved eye drops

Objective

Preservatives in artificial tears cause controversy. New developments such as the Purite? system have been introduced into the market, with the promise of little damage to the corneal surface. We wanted to give insight into the differences in the effect of preserved and unpreserved artifical tears on rabbit corneas cultured with the Ex Vivo Eye Irritation Test (EVEIT) system.

Materials

We compared the two artifical tears products Hylo Comod? and Optive? being dropped for 72?hours each hour one drop onto the corneal surface.

Methods

Each cornea was mechanically wounded with four epithelial defects on each cornea with a size of 3 to 4.5?mm². With n?=?4 corneas in the Hylo-Comod? and n?=?4 corneas in the Optive? group, we exposed the corneal surfaces to repeated doses of these artificial tears for 3?days. We observed healing of corneal erosions and surface epithelial integrity with sodium-fluoresceine staining under cobalt blue light illumination.

Results

We found nearly complete healing of epithelial defects with both artificial tears. The Hylo-Comod? group healed significantly faster. After 72?hours, the vast majority of epithelial defects were closed. All corneas exposed to Purite? showed superficial stippling, whereas the HyloComod? group did not show any stippling of the cornea; this difference was significant.

Discussion

Epithelial healing and recovery in the EVEIT system is observed in both groups, confirming the concept of artificial tears as a supporting factor of corneal health and healing. The superficial stippling of the corneal epithelium was observed only in the Optive? group. This effect is considered as a marker of dry eye syndrome, and should be prevented by the application of artificial tears. Preservative-free eye drops such as HyloComod? improve healing, and prevent symptoms of dry eye syndrome in the EVEITsystem. Compared to EVEIT results of former experiments with benzalconium chloride-preserved eye drops, Optive? promoted healing of corneal erosions.     

Anti-VEGF monoclonal antibody-induced regression of corneal neovascularization and inflammation in a rabbit model of herpetic stromal keratitis

Background

To determine the efficacy of bevacizumab (Avastin), an anti-VEGF monoclonal antibody, administrated via subconjunctival injection as a corneal anti-angiogenic treatment.

Methods

Right corneas of rabbits were infected with herpes simplex virus type 1, KOS strain. On day 13 post-infection (p.i.), animals were treated subconjunctivally (sc) with a single 10-μl dose (25 μg/μl) of bevacizumab (group A) or with the same volume of an isotype monoclonal antibody, as negative control (group B). All animals were observed clinically on days 2, 5, 7, 14, 21, and 28 p.i., and two corneas each day were obtained for histological assessment and viral titration.

Results

Viral replication was observed no longer than 5 days after infection. By day 7 a dense neutrophil invasion of the cornea was detected, which significantly increased while herpetic stromal keratitis progressed in severity. Positive outcomes observed following the treatment with bevacizumab, compared to control, included: (1) Total involution of neovascularization, (2) reduction in disease severity, (3) improved corneal translucency, (4) absence of scarring, (5) preservation of corneal thickness, (6) no neutrophil infiltration of the cornea.

Conclusions

Subconjunctival administration of bevacizumab induced involution of new vessels, abolished inflammatory response, and resulted in return of corneal function. Furthermore, bevacizumab is a novel approach for the treatment of herpetic stromal keratitis.     

In vitro effect of corneal collagen cross-linking on corneal hydration properties and stiffness

Background

The purpose of this study is to evaluate in-vitro the immediate effect of corneal collagen cross-linking (CXL) on corneal hydration and stiffness.

Methods

Forty-two corneal buttons from freshly enucleated porcine eyes were immersed in riboflavin 0.1% in dextran 20% dilution for 3 h in order for their hydration to reach equilibrium. Corneal buttons where divided into two groups; the first group was stored in dark conditions while the other group was irradiated with UV radiation (370 nm) for 30 min to simulate CXL according to the clinically applied protocol. After irradiation, all corneas were immersed in dextran 20% solution for 3 additional hours. Subsequently, each button underwent weighing, thickness measurement, and was mounted in a special device for the measurement of force versus deformation by compression. Finally, all corneal buttons were dehydrated for 48 h in a desiccating oven set at 62 °C and weighed again to obtain their dry mass. Hydration (%) of each button was calculated.

Results

Mean corneal hydration in the irradiated and the non-irradiated group of corneas was 69.8 and 72.2%, respectively (p?<?0.001). Differences in thickness and compressibility were not statistically significant. Thickness and hydration were positively correlated (Pearson’s r?=?0.714, p?<?0.001).

Conclusions

CXL causes corneal dehydration that can be detected immediately after the procedure. This phenomenon may contribute to increased mechanical stiffness of the cornea. A change in stiffness by means of compressibility could not be detected in porcine corneas.     

Properties of Corneas Reconstructed with Cultured Human Corneal Endothelial Cells and Human Corneal Stroma

Purpose

To examine the properties of corneas tissue-engineered with cultured human corneal endothelial cells (HCEC) and human corneal stroma.

Methods

Primary HCEC cultures were established from endothelial cell layer explants and propagated on culture dishes coated with bovine corneal endothelial extracellular matrix. A cell suspension of HCEC at the fifth passage was transferred onto human corneal stroma deprived of endothelial cells, and the corneas were gently centrifuged to enhance cell attachment. The cell density of the tissue-engineered corneas was examined after staining with alizarin red and trypan blue. The tissue-engineered corneas were histologically examined by light and electron microscopy. The pump function of the tissue-engineered corneas was measured using an Ussing chamber.

Results

The mean endothelial cell density of four tissue-engineered corneas was 2380 ± 264 cells/mm² (mean ± SD). HCEC on the tissue-engineered corneas had a morphology similar to HCEC in vivo. The pump function parameters of the tissue-engineered corneas were 55%–75% of those of normal corneas.

Conclusions

HCEC on the tissue-engineered corneas have morphology and cellular density similar to HCEC in vivo, whereas the pump function of the tissue-engineered corneas was lower than in normal corneas. Jpn J Ophthalmol 2005;49:448–452 © Japanese Ophthalmological Society 2005     

Expression von Matrixmetalloproteinase-19 in der humanen Kornea

Background

At present there are no data in the literature on the expression of matrix metalloprotein-19 in the human cornea. The aim of this study was to analyze the expression of matrix metalloproteinase-19 in the human cornea and to investigate its potential role in corneal wound healing using a MMP-19 knock-out mouse model.

Methods

A method with Western blotting and immunohistological staining for MMP-19 was performed using paraffin embedded human corneas. Excimer laser keratectomy was performed in wild type (wt) and MMP-19 knock-out (ko) mice and the rate of re-epithelialization was analyzed after 8 h and 18 h.

Results

MMP-19 was strongly expressed in the human corneal epithelium mainly in the basal cell layer. MMP-19 was not expressed in the corneal stroma. In the mouse model the size of the corneal lesion after 8 h was 83% (wt) and 89.9% (ko) of the initial area (p=0.09). After 18 h the lesion was 17% (wt) and 13.3% (ko) of the initial area (p=0.01). Laminin-5 was expressed in the migrating epithelial cells with no differences between wild type and knock-out mouse.

Conclusion

MMP-19 showed a strong expression in the basal cells of the human corneal epithelium. Corneal re-epithelialization was slightly faster in the MMP-19 knock-out mouse. No differences in the expression of laminin-5 could be detected.     

Anti-neovascular effect of chondrocyte-derived extracellular matrix on corneal alkaline burns in rabbits

Purpose

We investigated the effect of a chondrocyte-derived extracellular matrix (CDECM) on experimental corneal alkaline burns in rabbits.

Methods

Corneal neovascularization (NV) was induced by applying an 8-mm filter paper soaked in 1 N NaOH to the right central corneas of rabbits for 1 minute. Ten days later, the rabbits were randomly divided into three groups: the alkaline burn group, the CDECM transplantation group, and the human amniotic membrane (HAM) transplantation group. The left eyes were used as controls. CDECM and HAM were transplanted onto the corneal surface to completely cover the resected area and were subsequently sutured. On the 10th day after transplantation, the structural changes of the cornea were analyzed histologically. We examined the effects of CDECM on clinical NV features and on the expression of corneal NV markers.

Results

The alkaline burn produced significant NV and increased the corneal thickness. On day 10 after transplantation, the thickness, NV and opacity of the cornea were markedly decreased in the CDECM group (p?<?0.001). However, the HAM transplantation group did not exhibit improvements in these clinical parameters, and there were no significant differences relative to the burn group. In addition, the use of CDECM improved the healing of the cornea following the alkaline burn by disrupting the corneal epithelial proliferation and reducing the fibrotic changes of the stroma. The hallmarks of NV were significantly induced in the subepithelium by the alkaline burn, and these levels were also suppressed by CDECM. The CDECM suppressed corneal NV by inhibiting nuclear factor-kappa B (NF-κB) activation by blocking the PKC and Akt signaling pathways.

Conclusions

CDECM transplantation was markedly effective in healing alkali-burned corneas by modulating the translocation of NF-κB to the nucleus, thereby representing a promising material for the noninvasive treatment of ocular surface disease.     

Evaluation of corneal epithelial and stromal thickness in keratoconus using spectral-domain optical coherence tomography

Purpose

We sought to assess the corneal thickness of the epithelium and stroma in keratoconic and normal eyes by spectral-domain optical coherence tomography (SD-OCT).

Methods

Fifty-seven keratoconic and 20 normal eyes were studied. The eyes were examined by SD-OCT, and the keratoconic eyes were subdivided into 2 groups: those showing only smooth corneal thinning and corneal protrusion on the image (KC1 group) and those showing abnormalities in the Bowman layer or in the stroma, or in both (KC2 group). The thicknesses at the corneal vertex and at the superior, inferior, nasal, and temporal cornea 1.5 mm from the corneal vertex in the KC1 group were compared with those in the normal group. The OCT findings in the KC2 group were described.

Results

The epithelial thickness at the corneal vertex and at the inferior and temporal cornea, and the stromal thickness at all points were significantly thinner in the KC1 group than in the normal group (p < 0.05). The epithelial and stromal thicknesses at the corneal vertex were significantly correlated in the KC1 group and the normal group (r ²  = 0.427, p < 0.0001).The epithelial thickness in the KC2 group was not uniform owing to Bowman layer scarring, stromal scars, and secondary corneal amyloidosis.

Conclusions

Although epithelial thinning is associated with stromal thinning, when the cornea remains clear, the epithelial thickness may vary because of the irregularity of the stroma beneath the epithelium in patients with keratoconus.     

Comparison of corneal haze and visual outcome in primary DSAEK versus DSAEK following failed DMEK

Background

Descemet membrane endothelial keratoplasty (DMEK) is being proposed as the procedure of choice in corneal endothelial disease as it achieves better visual and refractive outcomes than Descemet stripping automated endothelial keratoplasty (DSAEK). Nevertheless, primary graft failure is frequent, especially during the learning curve, and secondary back-up procedure consists on DSAEK. We aim to compare corneal haze and visual acuity of patients undergoing primary DSAEK vs. patients undergoing DSAEK as a back-up procedure after primary DMEK failure.

Methods

This study is a comparative case series that included 19 eyes from 16 patients with early stages of corneal failure and limitation of daily activities after primary DSAEK or secondary DSAEK. A control group of non-operated corneas included 10 aged-matched normal eyes. The study was conducted at University Hospital Ramón y Cajal and Vissum Hospital, Madrid, Spain. Corneal densitometry readings and postoperative best-corrected visual acuity in subjects with primary and secondary DSAEK were recorded 6 months after the surgery using the Pentacam Scheimpflug system (Oculus, inc.,Wetzlar, Germany).

Results

In primary DSAEK median densitometry values (range) were statistically significantly higher (p?<?0.05) than normal subjects for the full thickness, posterior and anterior part of the paracentral cornea; and the anterior part of the central cornea. In secondary DSAEK, median densitometry values were statistically significantly higher than normal subjects at all levels of the central and paracentral cornea. In secondary DSAEK, median densitometry values (range) were statistically significantly higher than in primary DSAEK in the full-thickness, anterior part and interface of the central cornea and in the full-thickness and posterior part of the paracentral cornea. Median visual acuity between groups (p?=?0.47) was statistically better for the primary DSAEK group, which also had a higher percentage of patients achieving BCVA of ≥ 20/40 and ≥20/25 than the secondary DSAEK group (100 % vs. 62 % and 60 % vs. 0 % respectively).

Conclusions

There is an increase in central corneal light scattering after secondary DSAEK performed after a failed DMEK as compared to primary DSAEK. This has a negative impact on final visual acuity that needs to be considered in each patient when starting DMEK surgery.     

Bacterial culture after three sterilization methods for cataract surgery

Purpose

To compare bacterial cultures from three sterilization methods immediately before and after cataract surgery.

Design

A prospective randomized open-label group-comparison study.

Methods

We investigated 75 eyes in 73 consecutive patients undergoing cataract surgery. After swabbing the eyelid and surrounding area, patients were randomly assigned to one of 3 eye-washing methods: patients administered one drop of 5 % povidone–iodine (Group A); patients whose conjunctival sac was washed with 0.02 % chlorhexidine while everting the eyelid (Group B); or 0.02 % chlorhexidine as above but without eyelid eversion (Group C). In each group, specimens were collected from the conjunctival sac immediately before and after eye washing and again at completion of surgery, along with aqueous humor. The post-surgical condition of the corneal epithelium and the severity of anterior chamber inflammation were assessed by use of a slit-lamp microscope.

Results

In Groups A and C, the percentage of eyes with conjunctival bacteria decreased significantly from immediately before to immediately after washing (Group A, p = 0.008; Group C, p = 0.016), but there was no significant decrease in Group B (p = 0.125). Slit-lamp microscopy showed that inflammation of the anterior chamber 1 day after surgery was significantly milder in Group C than in Group B (p = 0.032).

Conclusion

Eye-washing methods without eyelid eversion are more effective in reducing conjunctival bacteria before surgery and anterior chamber inflammation after surgery than those with eyelid eversion.     

Bestimmung viskoelastischer Hornhauteigenschaften (korneale Hysterese) bei Patienten mit primärem Offenwinkelglaukom

Background

The ocular response analyzer (ORA) uses an air-pressure-triggered, dynamic, bi-directional corneal applanation method to measure biomechanical parameters of the cornea. Corneal hysteresis (CH) is defined as the difference in intraocular pressure recorded during inward and outward applanation. CH is therefore an indicator for the viscoelastic properties of the cornea.

Patients and methods

CH was recorded in non-glaucoma patients (80 eyes) as well as in patients with primary open angle glaucoma (POAG, 82 eyes). The correlation between CH and central corneal thickness (CCT) was analyzed.

Results

Mean CH was 10.6±2.2 mmHg in the non-glaucoma group and 9.3±2.2 mmHg in patients with POAG (p<0.01). CH and CCT showed a positive correlation in non-POAG patients, however no such correlation was found in the POAG group.

Conclusion

Patients with POAG show an alteration of biomechanical corneal parameters with a significant decrease in corneal hysteresis. A positive correlation between CH and CCT, which was seen in the non-glaucoma group could not be detected in the POAG group.     

Alterations of epithelial adhesion molecules and basement membrane components in lattice corneal dystrophy (LCD)

Background

The aim of the study was to investigate the histopathological and ultrastructural correlate of delayed epithelial healing in eyes with lattice corneal dystrophy (LCD).

Materials and Methods

Corneal buttons from 4 patients with LCD (two with subepithelial, two with stromal amyloid deposits) and 2 control corneas were examined. Cell-matrix adhesion molecules and basement membrane components of the corneal epithelium were analyzed by immunohistochemistry and hemidesmosomes between epithelium and stroma were quantified by transmission electron microscopy (TEM).

Results

By TEM well-developed hemidesmosomes anchored the basal epithelial cells to the underlying basement membrane in all normal and LCD corneas. Hemidesmosome density was not significantly different in subepithelial (224.7?±?34.1/100 µm) and stromal (234.3?±?36.3/100 µm) LCD compared to controls (241.3?±?26.8/100 µm). The basement membrane was interrupted in subepithelial, but continous in stromal LCD. Integrin α6 and ß4 staining formed a continous line along the basal surface of the corneal epithelium in control corneas, whereas it appeared discontinous and patchy both in subepithelial and stromal forms of LCD. Staining for αV integrin showed irregular staining patterns, i.e. enhanced labelling intensity in subepithelial and interrupted pattern in stromal LCD, respectively. Integrins α3, ß1, ß2, and ß5, dystroglycan, and plectin were not markedly different in dystrophic corneas. Type VII collagen showed a discontinuous staining in subepithelial forms of LCD. In stromal forms of LCD, type VII collagen staining occurred in additional patches underneath the epithelial basement membrane zone. Type XVII collagen staining was reduced in subepithelial LCD. Laminin-1, laminin-5 and laminin γ2 showed variable irregular staining patterns in dystrophic corneas with focal interruptions, focal thickenings, and reduplications of basement membrane. Some irregularities in corneas with subepithelial amyloid were observed for collagen types IV, V, and XVIII, laminin α1, α3, and γ1, nidogen-1 and -2, perlecan, fibrillin-1.

Conclusions

Immunohistochemical and electron microscopic evidence of structural alterations was found in LCD compared to normal corneas concerning cell-matrix adhesion molecules and basement membrane components. These alterations were more pronounced in dystrophic corneas with subepithelial amyloid deposits than in those with stromal deposits. Histopathological findings may correspond to reduced cell-matrix interactions and partly explain delayed epithelial healing in patients with lattice corneal dystrophy.     

Meta-analysis of Pentacam vs. ultrasound pachymetry in central corneal thickness measurement in normal, post–LASIK or PRK, and keratoconic or keratoconus-suspect eyes

Background

The aim of this meta-analysis is to evaluate the central corneal thickness (CCT) measurement differences between Pentacam (Oculus Inc., Germany) and Ultrasound Pachymetry (USP) in normal (unoperated eyes , myopic and astigmatic eyes without corneal disease or topographic irregularity), after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), and keratoconic or keratoconus suspected eyes. We assess whether Pentacam and USP have similar CCT differences in normal, thinner corneas after LASIK or PRK procedures, and kerotoconic or keratoconus suspected eyes.

Methods

Data sources, including PubMed, Medline, EMBASE, and Cochrane Central Registry of Controlled Trials on the Cochrane Library, were searched to find the relevant studies. Primary outcome measures were CCT measurement between Pentacam and USP. Three groups of eyes were analyzed: normal; LASIK or PRK eyes; and keratoconus suspected or keratoconic eyes.

Results

Nineteen studies describing 1,908 eyes were enrolled in the normal group. Pentacam results were 1.47 μm ,95 % confidence interval (CI) -2.32 to 5.27, higher than USP without statistically significant difference (P?=?0.45). Nine studies with total 539 eyes were included in the corneas after LASIK or PRK. The mean difference in the CCT measurement with Pentacam and ultrasound pachymetry was 1.03 μm, with the 95 % CI ?3.36 to 5.42, there was no statistically difference (P?=?0.64). Four studies with a total of 185 eyes were included in the keratoconic eyes or keratoconus-suspect group, however,the mean difference was ?6.33 μm (95 % CI ?9.17 to-3.49), which was statistically different between Pentacam and ultrasound pachymetry in the CCT measurement (P?<?0.0001).

Conclusions

Pentacam offers similar CCT results to ultrasound pachymetry in normal eyes, thinner corneas after LASIK or PRK procedures. However, in keratoconic or keratoconus-suspect eyes, Pentacam slightly underestimates the central corneal thickness than does ultrasound pachymetry, which may result from the difficulty in fixation of keratoconic eyes, misalignment of Pentacam and the variation of ultrasonic velocity due to the histological deformation.     

Corneal biomechanical properties in eyes with no previous surgery, with previous penetrating keratoplasty and with deep anterior lamellar keratoplasty

Purpose

To compare the biomechanical properties of the cornea in eyes with no previous surgery, with keratoconus with previous penetrating keratoplasty (PK) and with keratoconus with previous deep anterior lamellar keratoplasty (DALK) using the Reichert Ocular Response Analyzer (ORA).

Methods

One hundred twenty eyes of 120 patients were included in this prospective comparative study. Forty eyes were with no previous ocular surgery (group 1), 40 eyes were with previous PK for keratoconus (group 2), and 40 eyes were with previous DALK for keratoconus (group 3). Corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with ORA.

Results

The CH and CRF values in group 2 were significantly lower than in group 1 and group 3 (p = 0.001). The CH and CRF values were similar in group 1 and group 3. There was no statistically significant difference between group 1 and 3.

Conclusion

Although the post-PK keratoconus cornea has weaker biomechanical properties, post-DALK keratoconus cornea is similar to normal cornea. A cornea weakened by keratoconus can be strengthened with lamellar keratoplasty.     

Hornhautvernetzung mit hypoosmolarer Riboflavin-L?sung beim Keratokonus mit d��nner Hornhaut

Background

The aim of this study was to evaluate the 1-year results of 32 keratoconic eyes with thin corneas which were treated by hypo-osmolar riboflavin solution and ultraviolet A (UVA) collagen cross-linking (CXL).

Patients and methods

Patients with progressive keratoconus and a corneal thickness (CT) less than 400???m (without epithelium) were included in this study. The CT was measured with an ultrasound device (Tomey SP-3000, Nishi-ku, Nagoya, Japan). An increase in the maximum topographic K-value at the apex of keratoconus and a reduction in corneal thickness with or without changes in visual acuity (VA) within the last year were considered to be progression. A total of 32 eyes with an additional follow-up within 1 year were evaluated before and after the procedure. Examinations consisted of an evaluation of VA, corneal topography, slit-lamp microscopy and corneal thickness measurements.

Results

Preoperatively the mean corneal thickness (with epithelium) was 382.3±41.9???m and after removal of the epithelium the thickness of the cornea was reduced to 337.0±51.9???m. After the application of hypo-osmolar riboflavin solution the mean value increased to 451.8±46.7???m. Preoperatively the mean K-value of the apex of the keratoconus was 65.6±11.2 dopters, and 1 year after treatment this value remained relatively unchanged at 64.9±11.0 diopters (P=0.839). Mean VA at the time of the treatment was 0.63±0.37 logMAR and 1 year after the treatment this value was not statistically different (0.59±0.42 logMAR; P=0.662). In the last follow-up examination 1 year after the procedure all corneas were transparent without any scarring lesions in the stroma.

Conclusions

The results of this study using hypo-osmolar riboflavin solution in a cross-linking procedure for thin corneas showed a stability of keratoconus 1 year after CXL. Application of the hypo-osmolar riboflavin solution prevented cross-linked corneas from developing stromal scars.     

Immunohistochemical Observation of Amniotic Membrane Patching on a Corneal Alkali Burn In Vivo

Purpose

To investigate by immunohistochemical observation the effects of amniotic membrane (AM) patching on myofibroblastic differentiation and matrix metalloproteinase (MMP) expression in the corneal stroma after an alkali burn in vivo.

Methods

A corneal alkali burn was made by placing a circular piece of filter paper containing 1?N NaOH on the central cornea of rabbits. Burning was done unilaterally in each rabbit. Immediately after the wounding, in the AM group, AM was sutured onto the cornea and removed on day 1. Rabbits with no AM patching were controls. On day 14, corneas were excised and immunohistochemical observation was carried out using antibodies against α-smooth muscle actin (α-SMA), vimentin, MMP-1, MMP-2, MMP-9, and membrane-type1 (MT1)-MMP. Observation after Masson trichrome staining was also performed.

Results

In the AM group, α-SMA positive cells were noticeably fewer, and MMP-2, MMP-9, and MT1-MMP expression was clearly inhibited. Also, collagen fibers were more regularly arranged than in control eyes. The more proximate the cells were to the epithelial side, the fewer α-SMA-positive cells were observed in the AM group.

Conclusions

AM patching suppressed myofibroblastic differentiation and MMP expression in the stroma after an alkali burn. An inhibition gradient suggests that AM may release unknown soluble factors possessing some antiscarring capability.?Jpn J Ophthalmol 2007;51:3–9 © Japanese Ophthalmological Society 2007     

Effect of porcine chondrocyte-derived extracellular matrix on the pterygium in mouse model

Purpose

To investigate the effect of porcine chondrocyte-derived extracellular matrix (PCDECM) on an experimental mouse model of human pterygial epithelial cells.

Methods

Cultured human pterygial epithelial cells (hPECs) were stained with pan-cytokeratin (CK), CK3/2p, vimentin, and CK13 antibodies to characterize the cells. A pterygium mouse model was developed by injecting 1X10⁴ hPECs into the nasal subconjunctival space in athymic nude mice. PCDECM (25 mg/mL, 10 μL) was injected into the nasal subconjunctival space in the right eye 7, 10 and 14 days after the epithelial cell injection (PCDECM group). Image analysis was performed using ImageJ® to compare the lesion size. A histopathological analysis of the cornea was conducted to evaluate the state of the epithelium and the expression of pterygial epithelial cell markers.

Results

The isolated pterygial cells were positive for pan-CK, CK3/2p and vimentin, and they were negative for CK13 under immunofluorescence microscopy. On day 17 after epithelial cell injection, the size of the lesion compared to the entire cornea was increased to 37.1 % in the control group. However, in the PCDECM group, the lesion covered only 26.3 % of the entire cornea. The corneas of the pterygium mice showed an epithelium of irregular thickness, proliferation of the stroma, extracellular matrix breakdown and overexpression of pterygium-positive markers. However, these changes were significantly suppressed by the application of PCDEDM.

Conclusions

Our findings suggest that PCDECM seems to suppress pterygial epithelial cell growth and it could be used as a promising biomaterial for the noninvasive treatment of pterygium.