Change of all-trans retinoic acid content in the retina, choroid and sclera of the chick with different visual environment

• Aim: To study the role of the all-trans retinoic acid (RA) level of retina, choroid and sclera in chicken form-deprivation myopic eyes and form-deprivation myopic recovery eyes. • Methods: Seventy-five newly incubated carnivorous chicken were selected. Their left eyes were covered with semitransparent membrane to deprive form perception, and were divided into 2 trial groups: form-deprived group: covering for 14 days, and recovery group: covering for 11 days followed by uncovering for 3 days. Unoccluded eye in either group served as control eyes respectively. Eyeballs were extracted immediately after the chickens were executed at the dark room. Posterior ocular tissue of 8mm in diameter was taken by cornea drill on dry ice table. Retina, choroid and sclera fiber layer and cartilage layer were isolated rapidly under microscope. Every 3 specimen were treated as one sample. Standard solution of all-trans retinoic acid was added into blank sample and after sample processing procedures, standard curves were protracted. The peak position of retinoic acid in all tissues was found according to chromatography analysis of control standard substance. Finally the levels of retinoic acid in samples were calculated by computer chromatography workstation. • Results: In normal eyes, RA existed in retina, choroids and sclera, with choroids the most followed by sclera and retina, with fibrous layer contained more than cartilage layer (P<0.05). After 14 days of form-deprivation, RA in retina increased significantly (P <0.01, n =10), while decreased significantly in choroids, sclera cartilage layer and fibrous layer (P<0.01), among which scleral cartilage layer deceased the most. After 3 days recovery from form-deprivation, RA in retina decreased significantly (P<0.01), while increased significantly in choroids, which was 7 times greater than form-deprivation eyes. RA level in sclera cartilage layer and fibrous layer elevated significantly (P <0.01), with scleral fibrous layer contained more than cartilage layer (P < 0.05) • Conclusion: During form-deprivation and form-deprivation recovery, retinoic acid levels in retina, choroid, scleral fibrous layer and cartilage layer change significantly, and retinoic acid level in posterior scleral fibrous layer changes more than cartilage layer.