25 OPTM4102_Retina and RPE_record(1).pdf

OPTM4102 Retina and RPE Dr. Jason Charng [email protected] Acknowledgement of country The University of Western Australia acknowledges that its campus is situated on Noongar land, and that Noongar people remain the spiritual and cultural custo...

OPTM4102 Retina and RPE Dr. Jason Charng [email protected] Acknowledgement of country The University of Western Australia acknowledges that its campus is situated on Noongar land, and that Noongar people remain the spiritual and cultural custodians of their land, and continue to practise their values, languages, beliefs and knowledge. Artist: Dr Richard Barry Walley OAM Objectives Basic retinal landmarks Layers of the retina Structure and distribution of retinal vasculature RPE – structure and function  Posterior pole landmarks vision for central E response ① Macula, perifovea, parafovea, fovea, foveola, u umbo ② Optic nerve head/optic disc - * head https://www.eyephysics.com/ https://www.wikipedia.org/  blood vessel No overlying of. Foveal avascular zone Minimal overlying inner retina Centre of foveal avascular zone ~ Centre of macula ~ Point of fixation https://pubmed.ncbi.nlm.nih.gov/32308362/ Gross anatomy quarter of the than area lover less. retina total ↳ Central retina → circular area (diameter 6 mm) centred on fovea Peripheral retina stretches to ora serrata (~21 mm from fovea). Past ora serrata, no sensory retina The total retina is a circular disc of between 30 and 40 mm in diameter (Polyak, 1941; Van Buren, 1963; Kolb, 1991) https://pubmed.ncbi.nlm.nih.gov/30316018/ Retina Centra retina thicker than peripheral retina Outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, ganglion cell layer and nerve fibre layer ALL thicker in central Forea retina than peripheral retina https://imagebank.asrs.org/file/27720/wide-field-oct-montage Retina Retina Hotter Colour : abnormally thick. green idicate within normal range Cooler colour abnormally thin. : , Retina thickness data. Laverage). retina Thickness fr with ↑ of the age thickness. https://pubmed.ncbi.nlm.nih.gov/19427616/ https://pubmed.ncbi.nlm.nih.gov/12812895/ Macula yellowish pigmented. Central ~5.5 mm diameter From perifovea to umbo Macular pigment (found in macula lutea) – generic term describing yellow pigments found in the central macula, composed of three dietary carotenoids ① ~ Lutein ② ~ Zeaxanthin ③ ~ Meso-zeaxanthin Hypothesized functions of macular pigment 减少光散射和⾊差 ~ Reduce light scatter and chromatic aberration ~ Absorb blue light - Decrease oxidative damage on photoreceptors ~ Antioxidant properties  Come photoreceptors ↓ Fovea Comes are responsible for high special vision. Centre of the macula No rod photoreceptors - Maximum cone packing Centre of fovea – foveal pit O f https://webvision.med.utah.edu/book/part-i-foundations/simple-anatomy-of-the-retina/ No retina overlying in forcal pit.  Fovea (Eie Photoreceptor move is spars away as we fored. central the from · 7 central https://onlinelibrary.wiley.com/doi/full/10.1111/opo.12289 away from on forea. fored Retina 10 layes in Retina - Outermost layer : Retinal pigmented - epithelium, supporting - layer for the retina Innermost layer: Inner - limiting membrane - Retinal layers Neurons ~ 1st order: photoreceptors (rods and cones) ~ 2nd order: bipolar cells ~ 3rd order: ganglion cells ~ Interneurons: horizontal, mevisual amacrine cells signal.  all * need to remember. Retinal layers Outermost → Innermost 1. Retinal pigment epithelium: plays important role in photopigment regeneration, blood retinal barrier. Rich in melanin hence prevents light scatter 2. Photoreceptor layer: contains the outer and inner segments of the rod and cone photoreceptors 3. Outer limiting membrane/External limiting membrane (OLM/ELM): junctions formed by the apical process of Muller cells and photoreceptor cells 4. Outer Nuclear Layer (ONL): cell bodies of rods & cones 5. Outer Plexiform Layer (OPL): junction between rod and cone axons & dendrites of horizontal and bipolar cells Retinal layers 6. Inner Nuclear Layer (INL): cell bodies of horizontal, bipolar, amacrine and Müller cells 7. Inner Plexiform Layer (IPL): axons of bipolar and amacrine cells & dendrites of ganglion cells 8. Ganglion cell layer (GCL): Nuclei of the ganglion cells and displaced amacrine cells 9. Retinal nerve fibre layer (RNFL): fibres from ganglion cells traversing the retina to leave the eyeball at the optic disc 10. Inner Limiting membrane (ILM): end feet of the Müller cells Retinal layers Gray, Anatomy of the Human Body (1918) Retinal layers https://www.heidelbergengineering.com Photoreceptor layer Left to right: www.octscans.com RPE, IDZ, EZ, ELM/OLM EZ Photoreceptor layer ONL https://www.nature.com/articles/s41598-019-55484-1 Photoreceptor layer Comes in the forea are tightly parked to ensure sharp central vision https://webvision.med.utah.edu/  Photoreceptor layer e Arkare For me xop IDZ Photoreceptor layer www.octscans.com Left to right: IS/OS RPE, IDZ, EZ or IS/OS, ELM EZ · ELM OPL ONL - Bipolar Cells. https://pubmed.ncbi.nlm.nih.gov/19941415/ Photoreceptor layer Have highest retina central ↑ conc. in photorecepter & No Red retina. in central No photorecepters - - > at the optic disc. https://webvision.med.utah.edu/ Processes of Vitural Signal : Through vs Lateral pathway Through pathway: Photoreceptors → Bipolar cells → Ganglion cells Lateral pathway: Horizontal and amacrine cells, local feedback (i.e. horizontal cells to photoreceptors OR amacrine cells to bipolar cells), optimizing through pathway  Rod vs Cone convergence 126 million rods and cones converge to 1 million ganglion cells Free Higher convergence of rods than cones ~ Average of 120 rods to one ganglion cell ~ Average of 6 cones to one ganglion cell ~ Cones in fovea have 1 to 1 connection to ganglion cells Higher convergence ratio in rods – night vision instant at light Lower convergence in cones – visual - acuity ↓ lights sensitivity I brig isible hter. i work n vision colour vision by 3 different types of resolution in the retina for high Come photoreceptors. Central vs peripheral retina > - thinner Tod photoreceptor dominated. thicker https://webvision.med.utah.edu/ more cells. contain cells) g ganglion. Le.. Nerve fibre layer Ganglion cell axons travel within retinal nerve fibre layer (RNFL) towards the optic disc in an arcuate form ~ optic disc Fovea has no overlying RNFL Clear top and bottom halves split along the horizontal meridian https://pubmed.ncbi.nlm.nih.gov/24288622/ Optic nerve head (ONH) Appro 17 (4.5 to 5mm) or 2.5 disc diameter nasal to the fovea Pinkish, oval area 2 * 1.5 mm Optic cup – white central region, does NOT contain ganglion cell axons Neural retinal rim (between cup and disc) contains ganglion cell axons https://www.youtube.com/watch?v=lvFFOb9nRiY www.entokey.com Glial cells Support cells for retinal neurons 3 types ~ Müller cells ~ Astrocytes ~ Microglia (in every retinal layer): any trauma to the retina these cells functions as macrophage, and engage in phagocytosis of degenerating retinal neurons. https://pubmed.ncbi.nlm.nih.gov/25873768/ Müller cells Runs through the entire retina Clears metabolic waste Facilitates neurotransmitter recycling Facilitates photopigment recycling Maintains ionic balances Optic fibre transferring light onto photoreceptors https://webvision.med.utah.edu/ Astrocytes Cell bodies and processes found in RNFL Peak distribution on ONH Axonal and vascular glial sheaths, maintain blood-retina barrier of inner retina blood vessels https://webvision.med.utah.edu/ Retinal pigment epithelium (RPE) Single-layer cell Between photoreceptors and choroid Connected by tight junctions ~Acts like a sieve from choriocapillaris to RPE Basolateral membrane is in contact with Bruch’s membrane Retinal pigment epithelium (RPE) https://pubmed.ncbi.nlm.nih.gov/15987797/ Retinal pigment epithelium (RPE) Forms tight junction between choriocapillaris and photoreceptors – part of the blood-retina barrier https://pubmed.ncbi.nlm.nih.gov/27493715/ Summary Anatomical landmarks of the retina Define retinal layers Rod vs cone vision Glial cells of the retina RPE function and as blood-retina barrier