Purpose
To determine the molecular basis of corneal avascularity during wound healing and determine the role of angiogenic and antiangiogenic factors in corneal vasculogenesis.

Corneal angiogenic privilege: angiogenic and antiangiogenic factors in corneal avascularity, vasculogenesis, and wound healing (an american ophthalmological society thesis)

To evaluate the efficacy and safety of topical 0.005% tacrolimus eye drop for treatment of refractory vernal keratoconjunctivitis (VKC). This prospective study included 20 eyes of 10 patients with refractory VKC, who had active symptomatic disease despite conventional medications including topical steroids. After discontinuing all other medications, patients were treated with topical 0.005% tacrolimus eye drop four times a day. Changes in subjective symptoms and objective signs after treatment were evaluated, and development of possible complications was assessed. Mean age of patients was 21.3±7.4 years and mean duration of VKC was 12.1±5.8 years. After starting tacrolimus eye drop, patients were followed for a mean duration of 10.7±3.7 months (range, 6–15 months). All symptoms including itching, redness, photosensitivity, foreign body sensation, and mucus discharge improved after the treatment; itching was the first symptom to show dramatic relief. In addition, there was improvement in objective signs including conjunctival hyperaemia, conjunctival papillary hypertrophy, giant papillae, limbal hypertrophy, corneal punctate epithelial erosions, and corneal pannus; conjunctival hyperaemia was the first sign to show improvement. No patient required addition of other medications including steroids for further relief. Any attempt to discontinue tacrolimus eye drop was associated with recurrence of patients’ symptoms and signs, necessitating continued use of the medication during the entire follow-up time. No ocular complication related to tacrolimus was noted. Topical 0.005% tacrolimus eye drop seemed to be a safe and effective treatment for steroid-resistant refractory VKC; however, long-term use was needed to control the disease.

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Topical 0.005% tacrolimus eye drop for refractory vernal keratoconjunctivitis

Corneal neovascularization is defined as the presence of vessels within the normally avascular corneal stroma. This physiopathological process is the consequence of local hyper-expression of pro-angiogenic factors in response to tissue damage. These new vessels (neovessels), initially immature and poorly developed, predispose the cornea to lipid exudation, inflammation, and scarring. Additionally, the influx of vascular cells into the stroma induces a loss of the cornea's immune privilege, resulting in a higher rate of graft rejection. In this literature review, we touch on epidemiological, physiopathological, and clinical aspects of corneal neovascularization, as well as secondary complications.

Néovascularisation cornéenne : aspects épidémiologiques, physiopathologiques et cliniques

PURPOSE. To evaluate the role of deep anterior lamellar keratoplasty (DALK) in acute ocular chemical burns. METHODS. The study was conducted in 50 eyes of 50 patients (24 male, 26 female) with average age of 38.3±14.3 years. DALK in 5 eyes (10%), DALK with quadrant conjunctivo-limbal graft in 25 eyes (50%), and DALK with amniotic membrane in 20 eyes (40%) were performed along with conventional medical therapy. Controls who were matched in all respects (50 eyes) were given medical therapy only as they refused surgical intervention. R ESULTS. Follow-up of cases ranged from 6 to 48 months (mean 21.5±14.18 months). Forty-three eyes (86%) could be restored with clear cornea as compared to 6% in control group. The visual acuity improvement was seen in 100% with good score (0.49±1.46) in DALK group as compared to 18% with low score (0.03±0.01) in control group (p<0.0001). Visual acuity improvement in DALK was 6/12 in 19 eyes (38%), 6/24 in 28 eyes (56%), and 6/36 in 3 eyes (6%) but was 3/60–6/60 in 6 eyes (12%) and finger counting only in 3 eyes (6%) in control group. Eyes with advanced grade II and grade III showed better improvement than those with burns of grade IV (p<0.05). The discomfort was relieved and epithelial healing was achieved immediately in DALK as compared to a prolonged course in control group (p<0.0001). Vascularization presented in 38% in DALK with least score (0.13+0.15) as compared to 100% in control group with high score (2.8±0.30). Perforation of cornea was seen only in 2 cases (4%) in DALK with low score (0.03±0.10) as compared to 88% in control group (1.33±0.20). Symblepharon was seen in 2% in DALK group as compared to 62% in control group. C ONCLUSIONS. DALK with and without conjunctival or amniotic membrane transplantation is an effective technique in restoring the integrity of the eye with an excellent graft transparency in 86% and improvement in visual acuity in 100% of the acute chemical burns. (Eur J Ophthalmol 2008; 18: 517-28)

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Evaluation of therapeutic deep anterior lamellar keratoplasty in acute ocular chemical burns.

Corneal angiogenic privilege: angiogenic and antiangiogenic factors in corneal avascularity, vasculogenesis, and wound healing (an american ophthalmological

First-principles calculations to investigate pressure effect on structural, elastic and thermodynamic properties of AlCu, Al2Cu and Al4Cu9

OBJECTIVES To understand the clinical significance of corneal limbus transplantation on alkali burns. METHODS 14 New Zealand rabbits were used, 1.0 mol/L NaOH solution was placed on the anterior surface of the eyes for 1 minute. Limbal autograft transplantation was performed on 7 rabbits immediately after the burn. The other 7 rabbits were used as controls. The follow-up period lasted for 1 month and then the histopathological changes of corneas were observed under light and scanning electron microscopes. RESULTS Faster corneal epithelial healing, less corneal neovascularization and inflammatory cell infiltration occurred in the operative group. CONCLUSIONS Early limbal autograft transplantation can accelerate corneal epithelial healing, restrain corneal neovascularization and inflammatory response, therefore it can prevent corneal ulceration.

Early corneal limbal autograft transplantation after alkali burns

Microstructure evolution and mechanical properties of CuW/Al interface fabricated by infiltration and vacuum hot-pressing diffusion bonding

OBJECTIVE: To evaluate the general cause of limbal allograft transplantation rejection and the effects of the immunosuppressant FK506. METHODS: Limbal deficiency models were established in 48 New Zealand rabbits, which were randomized into three groups of 16 rabbits each. Limbal allograft transplantation was performed one month later. After transplantation, the FK506 group, the CsA group and the untreated group were treated with FK506 eye drops (0.5 g/L), 1% CsA eye drops and physiological saline, respectively. Graft survival and ocular surface were observed clinically for 10 weeks. Impression cytology was performed on the central cornea of the rabbit one month after limbal ablation, 1 day before allograft transplantation, and two and four weeks after transplantation. The expression of CD25 in peripheral T cells was identified dynamically one day before and one and eight weeks after transplantation. The expression of CD25 on the limbal allograft and lymphocyte infiltration was also identified dynamically the fourth, eighth and tenth week after transplantation. RESULTS: Conjunctivalization of corneal epithelium was found in the limbal deficiency model by impression cytology. Two weeks after limbal allograft transplantation, the central corneal epithelium regained corneal phenotype. Four weeks later, the ocular surface of FK506 group and CsA group continued to express corneal phenotype. Epithelium rejection appeared first in the untreated group (P < 0.05), which had the highest level of the lymphocyte infiltration and the expression of CD25 in peripheral blood and allografts after limbal allograft transplantation (P < 0.05). Epithelium rejection occurred next with the CsA group. FK506 group epithelium rejection occurred last and had the lowest level of the lymphocyte infiltration and the expression of CD25 in peripheral T cell and limbal allografts. CONCLUSIONS: Topically administered FK506 eye drops early after limbal allograft transplantation can delay allograft rejection by effectively inhibiting the expression of CD25 in peripheral T cells and limbal allografts. Also, FK506 is more effective than CsA.

The study of FK506 eye drops preventing and treating immune rejection on limbal allograft transplantation

In this study, the bonding of a CuW/Al composite with a Ni interlayer was designed and established by vacuum hot-pressing diffusion bonding. The interfacial microstructure was systematically discussed based on experimental characterization and first-principles calculations. The result indicated that the interface consisted of intermetallic compounds (IMCs) of Al3Ni2 and a few of Al3Ni. The interfacial microstructure significantly differed from the interface without the Ni interlayer. The growth kinetics of the Al3Ni2 layer followed a parabolic behavior, which was mainly affected by the volume diffusion mechanism. The interfacial thickness decreased significantly, and the average thickness was ~35 μm. The microstructural evolution revealed that Al3Ni2 was the phase that was formed first. By introducing a Ni interlayer, the interfacial strength was significantly enhanced due to the IMCs that were changed from Al–Cu and Al–W IMCs to Al–Ni IMCs. The maximum shear strength reached 90.9 MPa, which was increased by 76% compared to that of the sample without the Ni interlayer. An analysis of the fracture morphology analysis showed that the crack was prone to exist at the Al3Ni2/Ni interface and presented a cleavage fracture characteristic.

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Jian Chen

Papers

First-principles calculations to investigate pressure effect on structural, elastic and thermodynamic properties of AlCu, Al2Cu and Al4Cu9

Early corneal limbal autograft transplantation after alkali burns

Microstructure evolution and mechanical properties of CuW/Al interface fabricated by infiltration and vacuum hot-pressing diffusion bonding

The study of FK506 eye drops preventing and treating immune rejection on limbal allograft transplantation

Investigation on Interface of CuW/Al Composite Using Ni Interlayer by Vacuum Hot-Pressing Diffusion Bonding