2. The vitreous humor is a transparent jelly like structure which helps to maintain the shape of the eyeball and optical function.it has all the properties of the hydrophilic gel, undergoing turgescence. It contains a few cells and an obliterated canal known as hyaloids canal it has no blood vessels. Its surface is condensed to form thin membrane called the hyaloids membrane.

3. it is due to conversion of the colloidal gel into a sol Causes: 1)Senility 2)Degenerative myopia 3)Uveitis 4)Trauma-concussion or intraocular foreign body 5)Treatment of retinal detachment by diathermy or light coagulation

4. Clinical significance: 1)Development of retinal detachment 2)During lens extraction-posterior dislocation of lens and vitreous loss may occur. That is why in cases of degenerative myopia, planned extracapsular lens extraction is indicated.

5. Subjectively they are seen entoptically as muscae volitantes. Any opacity in the eye which casts a shadow upon the sentient elements of the retina (rods and cones) will appear as dark spot in the field of vision. However, an opacity in the retinal blood vessels (RBCs) will not produce muscae

6. Causes: 1.Congenital remnants of the hyaloid vascular system. 2.Endogenous opacities A.Coagula of the colloid basis of the gel- senility, degenerative myopia. B.Crystalline deposits- asteroid bodies, synchisis scintillans. 3.Exogenous opacities

7. A.Protein coagula- plasmoid vitreous as in iridocyclitis and choroiditis. B.Exudative cells. C.Blood. D.Tissue cells-epithelial cells, histocytes. E.Tumors cells. F.Pigment-melanin, haemosiderin.

8. Symptoms: 1.Muscae volitantes may appear in the form of black dots, lines or cobwebs. 2.When many vitreous opacities are present there may be haziness of vision. Vision is often best in the morning before the vitreous has been stirred up by movements of the eye. 3.In a myopia sudden increase in muscae volitantes may herald the onset of retinal detachment.

9. Signs: The opacities may be seen: 1.With the slit lamp. 2.As black opacities moving independently of the movements of the eye by distant direct ophthalmoscopy. 3.With an ophthalmoscope with a +10 D lens.

10. Treatment: 1.The patient should be advised to ignore the opacities as much as possible. 2.Treatment of the underlying cause –iridocyclitis-choroiditis. 3.Vitrectomy in desperate cases.

11. synchisis scintillansAsteroid bodies or asteroid hyalitis or Benson's disease 1. age 45-60 years. 2. Bilateral. 3. Flat angular crystalline appearance- shower of golden rain. 4. They may lie hidden at the bottom of the vitreous: when the globe is moved they leap into sight and finally settle down. 5. Cholesterol crystals. 6. Occurs in degenerated fluid Vitreous. 1. Age 45-60 years. 2. Unilateral. 3. Appearance with ophthalmoscope looking like stars in the night sky. 4. When the eye is moved the bodies execute a lazy wave like excursion and return to their original location. 5. Chemical composition calcium soaps. 6. Occurs in relatively healthy vitreous.

12. Source: 1) Retinal blood vessel- veins or arteries. 2) Vessels of the ciliary body. 3) New vessels growing into vitreous-retinitis proliferans. 4) Spilling over of hyphaema after cataract extraction.

13. Causes: 1.Trauma. 2.Diabetes mellitus with proliferative retinopathy. 3.Hypertension. 4.Eales’ disease. 5.Blood dyscrasias - anemia, hemophilia, sickle cell disease.

14.  Small vitreous hemorrhage may get absorbed but in recurrent hemorrhages retinitis proliferans may develop. Treatment: 1.Photocoagulation in cases of diabetic retinopathy. 2.Vitrectomy.