| At present, myopia is a commonly and frequently encountered ammetropia. It's not clear about it's pathogenesis but form deprivation theory has played an important role in the study of myopia's pathogenesis, which means multiple methods which effect the normal image formation in the retina can make the axial length become longer and lead to myopia. In the past several years, the relationship between growth factors and form deprivation myopia gradually became importance to people. We designed to establish animal model of form deprivation myopia in chicken. Morphological observation immunohistochemical and ELISA technique were used to study the pathogenesis of form deprivation myopia and the relationship between bFGF and the incidence and development of form deprivation myopia. l.The expression of bFGF in the retina of the form deprived eyesMaterials and Methods: Thirty 2-day-old healthy male hailan chicken were selected. All the right eyes underwent form deprivation with translucent goggles, and the left eyes were used as control. 2 weeks later, the goggles were removed and the refractive state was determined by means of streak retinoscopy (without cycloplegia). The eyes were extracted and the axial length and equatorial diameter were determined by means of vernier caliper, routine3um paraffin sections were taken. Hematoxylin-eosin staining were done, and morphological changes in form deprived chicken's retina and sclera was detected under light microscope. Streptavidin-biotin-peroxidase complex immunohistochmical method was used to study the expression of bFGF protein in the occluded retina.Results: (1) Average refractive value of occluded eyes and control eyes were -20.15+7.38 D and 0.40+0.28 D, there was significant difference between them (p<0.01). Axial length of occluded eyes was notably longer compared with that in the control (p<0.01). All these results confirmed that form deprivation led to myopic refractive abnormality. (2) Hematoxylin-eosin staining showed that occluded retina was thinner than that of the control eyes, the posterior cartilaginous sclera was thicker and the fibrous sclera of the same section was thinner than the control. (3) Immunohistochemical staining shows that bFGF positive expression was detected in the cytoplasm, displaying as yellow or pale brownpellet, and bFGF positive cells were mainly distributed in the inner nuclear layer and ganglion cell layer, which were mainly amacrine cells in the inner nuclear layer. Ten visual fields under oil immersion objective were randomly selected, the average number of positive cells were used as average number of positive cells per oil immersion x objective visual field, in the control eye, which was 1.71+0.61 and 3.06+1.10 in the inner nuclear layer and ganglion cell layer respectively. In the occluded eyes, the number of average positive cells was 0.71 +0.52 and 1.77+1.28 in the inner nuclear layer and ganglion cell layer respectively. There was significant difference compared with that in the control eyes (p <0.01). 2. Study of the change of bFGF content in sclera during the development of form deprivation myopia in chickenMaterials and Methods: One hundred male hailen chicken were selected ,the method to set up animal model was the same as the first part. After the right eyes were randomly occluded for 1 3 5 7 and 14 days, respectively, 20 chicken were randomly selected, the refractive state was determined by means of streak retinoscopy (without cycloplegia), the axial length were measured by vernier caliper. Five corresponding tissue specimens from each group were pooled as one sample. Using a surgical trephine, 8mm diameter tissue buttons were excised from the part of each posterior hemisphere. Specimens of retina-retinal pigment epithelium (RPE)- choroid andsclera were seperated from these tissue samples. The five tissue buttons from each group were homogenized together in 0.01 M Tris Hcl, PH 8.0, which contained 2 M NaCl and 0.5% Triton X-100, using a glass homogenizer. Insoluble material was removed from thehomog... |
