الفهرس 
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Abstract
This present study was carried out on 14 apparently-healthy dogs. Their ages varied from 7 months to 3 years and body weights ranged from 30 to 40 Kg. The animals were divided into 2 groups (7 dogs for each): In the AM group , a corneal ulcer was induced and treated with Human Amniotic membrane transplantation; While in the control group a corneal ulcer was induced without treatment . Four dogs were submitted to histopathological examination (Two dogs from each group).
The induction of corneal ulcer was done using a corneal trephine (8.5 mm) after ketamine (general anesthesia) that was premedicated by xylazine as a sedative. This procedure was done on all corneas. In the AM group, AM was fixed on the cornea by suturing it using an 8-0 vicryl suture material and covered by a 3rd eyelid flap. Thickness of cornea was measured just before operation.
A local antibiotic eye drop, such as pharmagatin , was used on all operated eye after surgery till complete epithelial healing to prevent secondary bacterial infection. The 3rd eye lid flap was removed after 7 days post operatively.
Clinically, the corneal ulcer in all dogs were evaluated on Day 3, 7, 11, 15, 30 and 45 by naked eye examination of epiphora , ocular discharge , vascularization and opacity. Also, fluorescein staining and measurement of ulcer diameter by a caliper was carried out. Measurement of corneal ulcer using an ultra-sonic pachymetry was carried out just after surgery and on Day 45.
For histopathological examination, the globe of the eye ball of two dogs from each group were enucleated under a general anesthesia on Days 15 and 30 after surgery. Corneas were fixed in 10% neutral buffered formalin for 24 hours, routinely-processed, embedded in paraffin blocks and stained with haematoxylin and an eosin stain. Re-epithelization of the corneal epithelium, evaluation of inflammatory cells infiltrations, fibroblasts proliferation (fibroplasia), and newly formed vessels (angiogenesis), were assessed .The thickness of the newly generated cornea was measured by using Image J analysis software.
from results of histopathology, The corneal stroma in the control animal at day 15 post–surgery was rich in inflammatory cells predominantly neutrophils and eosinophils (+++), and few macrophages (+). In addition, the newly created granulation tissue, rich in fibroblasts (+++) and newly formed blood vessels (+++), was observed together with severe edema within the corneal stroma.
On the other hand, at day 15, presence of minimal infiltration of inflammatory cells predominantly macrophages (+) and very few neutrophils, granulation tissue rich in fibroblasts (++++) and very few newly formed blood vessels (+) were also observed in the stroma of AM group. on Day 30 post-surgery, the whole cornea of the control group was thicker than that of the AM group.
The result of this study revealed that a freeze – dried human amniotic membrane has several advantages as it is easily-handled, ready to use and not time-consuming. AM has anti-inflammatory, a anti-bacterial, anti - angiogenic and anti-fibrotic effects on corneal ulcer healing. Epithelization was completed after 15 days and 35 days in both the AM group and the control group respectively.