Retina and Vitreous

1. Retina and Vitreous Retina

2. Retina • The innermost layer of the eyeball. • It is extremely thin and transparent (0.5mm) • It contains visual receptors of the eye • The retinal neurons transmit the picture through the optic nerve fibers to brain for perception

3. Layer of retina • There are 10 layers in the retina • Retinal pigment epithelium • Layer of rods and cones • External limiting membrane • Outer nuclear layer • Outer plexiform layer • Inner nuclear layer • Inner plexiform layer • Ganglion cell layer • Nerve fibre layer • Internal limiting membrane

4. Rods Function best in dim light There are 125million rods in the retina Rods are relatively poor in visual details Cones Function best in daylight There 6 million cones in the retina Cones enable us to see small visual details Helps to visualize the colors Retinal receptors* The retinal receptors are divided into two main populations*Rods* Cones

5. Fovea and ora serrata • The cones form a concentrated area in the retina known as fovea • It lies in the center of the macula lutea • The junction of the periphery of the retina and ciliary body is called ora serrata

6. Vitreous • The Vitreous humour is a transparent gel that provides a clear optical medium. • It is helps to keep the three layers apposed to each other • It occupies approximately 80% of the volume of the globe. • The vitreous consist of water, collagen fibrils, molecules of hyaluronic acid, peripheral cells and mucopolysacharides forming a gel like material. • It nourishes lens, ciliary body and the retina.

7. Examination of vitreous • Examination of the anterior vitreous can be carried out with slit-lamp. • The vitreous should be observed for cells and any opacities.

8. Changes in the vitreous with age • Between 40 and 70 years of age in most individuals and earlier in myopes, vitreous liquefaction or syneresis occurs. • The vitreous mass gradually shrinks and collapse, causing its separation from the retina, a condition known as posterior vitreous detachment .(PVD). • Condensation of the vitreous fibrils are present within this liquefied vitreous are visible as floaters.

9. Retinal Diseases

10. Diabetic Retinopathy • It is now a major cause of blindness in retina. • Patient who is suffering from diabetic mellitus • Classification • Non proliferative diabetic retinopathy (NPDR) • Micro aneurysms • Hemorrhages • Hard exudates • Retinal odema • Proliferative diabetic retinopathy (PDR) • New vessels at the disc • Fibrovascular bands • Vitreous detachment • Vitreous hemorrhage

11. Investigations and Treatment • Urine and Blood Sugar examination • FFA (Fundus flourescein angiography) • Management Medical Treatment : Good diabetic control Laser Treatment : Photocoagulation to stop leaking from retinal vessels and bleeding from new vessels Surgical Treatment : Vitrectomy is done in case of vitreous hemorrhage, traction retinal detachment

12. Hypertensive Retinopathy • Vascular Changes in the retina associated with systemic hypertension • Grade I - Mild generlaised narrowing of arterioles in small branches • Grade II - Marked generalized narrowing associated with focal narrowing of arterioles • Grade III - Grade II changes and also hemorrhage cotton wool spots and hard exudates • Grade IV - All changes of grade III plus papillodema Management: • No special management is required for the retinopathy as most of the changes are reversible with adequate control of blood pressure

13. Retinaldetachment • Separation of retina from the retinal pigment epithelial layer • Myopia • Retinal Degeneration • Trauma • Floaters • Flashes of light • Sudden painless loss of vision • Scleral buckling procedure

14. Retinitis pigmentosa • It is a hereditary condition of the retina affecting the rods • Features • Night blindness • Tubular vision : advanced cases • Fundus changes: • Waxy pallor of disc • Narrowed vessels • Bony spicule pigmentation

15. Treatment • No permanent cure at present • Supportive treatment • Vitamin A • Low vision aids • Visual rehabilitation • Genetic counselling • Affected individuals discouraged to have kids

16. Central Serous retinopathy (CSR) • IT id due to detachment of retina in the macular region due to accumulation of fluid resulting in defective vision • Sudden onset of painless loss of vision • Central scotoma • Micropsia (object appears small) • Metamorphopsi (object irregularity) • Mild elevation of macular area • Foveal reflex absent • Reassurance • Long standing cases : laser photocoagulation

17. Retinoblastoma • It is a malignant tumour of the retina occuring in children under 5 years • White reflex over the pupil • Squint • Radiation therapy, chemotherapy • Photocoagulation • Cryotherapy • Enucleation/excentration

18. Vitreous hemorrhage • Bleeding into the vitreous • Blood vessels in to retina • Causes • Trauma to the eye • Diseasea of the blood vessels • Diabetic retiopathy • Inflammation of the retinal veins • Diseases of retina • Retina tears • Retinal detachment