General Anatomy of the Eye & Degenerative Diseases of Human Retina Jennifer Hsieh Psy 159 Physiological Basis of Perception Physiological Basis of Perception1/11/2005.

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General Anatomy of the Eye General Anatomy of the Eye & Degenerative Diseases & Degenerative Diseases

of Human Retina of Human Retina Jennifer HsiehJennifer Hsieh

Psy 159Psy 159

Physiological Basis of PerceptionPhysiological Basis of Perception

1/11/20051/11/2005

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BackgroundBackground

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Key TermsKey Terms

Vitreous humorVitreous humor – fluid in major chamber of eye. – fluid in major chamber of eye. Retina Retina – encodes the info as a neural signal to transmit – encodes the info as a neural signal to transmit

to the brain. to the brain. Macula luteaMacula lutea – pigmented central region of the retina – pigmented central region of the retina

containing fovea. containing fovea. FoveaFovea – greatest capacity for fine detail discrimination. – greatest capacity for fine detail discrimination. Optic nervesOptic nerves – bundle of ganglion cell axons carrying – bundle of ganglion cell axons carrying

visual info.visual info. CorneaCornea – where light enters the eye. – where light enters the eye. IrisIris – a smooth ring of muscle with a central opening. – a smooth ring of muscle with a central opening. PupilPupil – central opening. – central opening. Lens Lens – helps the cornea to produce a focused image.– helps the cornea to produce a focused image.

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Anatomy of the RetinaAnatomy of the Retina

Photoreceptors  (Rods and Cones)

Outer Plexiform Layer

Inner Nuclear Layer  

Inner Plexiform Layer 

Ganglion Cells 

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The RetinaThe Retina Receptors – Receptors – absorb photons & begin to create neural signals. absorb photons & begin to create neural signals.

Outer plexiform layerOuter plexiform layer – – the receptors terminate here.the receptors terminate here.

Inner nuclear layerInner nuclear layer - - Horizontal cells:Horizontal cells: responsive to lights across a wide area of the responsive to lights across a wide area of the

retina.retina. Bipolar cells:Bipolar cells: response can be either hyperpolarizing (light falling response can be either hyperpolarizing (light falling

directly on it) or depolarizing (light falling to the side). directly on it) or depolarizing (light falling to the side). Amacrine cells:Amacrine cells: produce response (transient / phasic) when the produce response (transient / phasic) when the

light level changed. light level changed.

Inner plexiform layerInner plexiform layer – – signals within bipolar cells conducted to here. signals within bipolar cells conducted to here.

Ganglion cellsGanglion cells – – receive the end products of all the previous receive the end products of all the previous

processing and communicate it to the brain. processing and communicate it to the brain.

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Retinal PhotoRetinal Photo - - OphthalmoscopeOphthalmoscope

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Degenerative diseases of the Degenerative diseases of the human retinahuman retina

In some eye diseases, the retina becomes In some eye diseases, the retina becomes compromised, and the degenerative changes compromised, and the degenerative changes lead to serious damage to the nerve cells lead to serious damage to the nerve cells that carry the messages about the visual that carry the messages about the visual image to the brain.image to the brain.

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Age Related Macular DegenerationAge Related Macular Degeneration

Age related macular degeneration - the macular area and fovea become compromised due to the pigment epithelium behind the retina degenerating and forming white spots.

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GlaucomaGlaucoma

Glaucoma - the pressure within the eye becomes elevated. The pressure rises because the anterior chamber of the eye cannot exchange fluid properly by the normal aqueous outflow methods.

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Retinitis PigmentosaRetinitis Pigmentosa

Retinits pigmentosa - a hereditary disease of the retina. Most of the faulty genes affect the rod photoreceptors. Characteristic pathology is the occurrence of black pigment in the peripheral retina and thinned blood vessels.

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Diabetic RetinopathyDiabetic Retinopathy

Diabetic retinopathy - a side effect of diabetes that can cause blindness. The vital nourishing blood vessels of the eye become damaged, distorted and multiply in uncontrollable ways.

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Now that we are done, Now that we are done, take the quiz! take the quiz!

1. The _____ transmits electrical impulses from the eye to the 1. The _____ transmits electrical impulses from the eye to the brain.brain.A. LensA. LensB. Optic nerveB. Optic nerveC. Vitreous humorC. Vitreous humor

2. The eye works a lot like a...2. The eye works a lot like a...A. CameraA. CameraB. ComputerB. ComputerC. ProjectorC. Projector

3. Below is a view of the fundus of the retina in a patient with 3. Below is a view of the fundus of the retina in a patient with ______. ______. A. Glaucoma A. Glaucoma B. Healthy Eye (Normal) B. Healthy Eye (Normal) C. Macular degenerationC. Macular degeneration

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ReferencesReferences Hagerman, G.S. and Johnson, L.V. (1991) The photoreceptor-Hagerman, G.S. and Johnson, L.V. (1991) The photoreceptor-

retinal pigmented epithelium interface. "Principles and retinal pigmented epithelium interface. "Principles and Practice of Clinical Electrophysiology of Vision" (Eds. Practice of Clinical Electrophysiology of Vision" (Eds. Heckenlively, J.R. and Arden, G.B.) Mosby Year Book, St. Heckenlively, J.R. and Arden, G.B.) Mosby Year Book, St. Louis, 1991, pp. 53-68.Louis, 1991, pp. 53-68.

Henkind , P., Hansen, R.I. and Szalay, J. (1979) Ocular Henkind , P., Hansen, R.I. and Szalay, J. (1979) Ocular circulation. In "Physiology of the human eye and visual circulation. In "Physiology of the human eye and visual system" (Ed. Records, R.E.) pp 98-155. Harper & Row, new system" (Ed. Records, R.E.) pp 98-155. Harper & Row, new York.York.

Kolb, H. (1991) The neural organization of the human retina. Kolb, H. (1991) The neural organization of the human retina. In "Principles and Practices of Clinical Electrophysiology of In "Principles and Practices of Clinical Electrophysiology of Vision" (Eds. Heckenlively, J.R. and Arden, G.B.) Mosby Year Vision" (Eds. Heckenlively, J.R. and Arden, G.B.) Mosby Year Book Inc. , St. Louis, pp. 25-52.Book Inc. , St. Louis, pp. 25-52.

Polyak, S.L. (1941) The Retina. University of Chicago Press, Polyak, S.L. (1941) The Retina. University of Chicago Press, Chicago.Chicago.

Van Buren, J.M. (1963) The retinal ganglion cell layer. Van Buren, J.M. (1963) The retinal ganglion cell layer. Charles C. Thomas, Springfield, Illinois.Charles C. Thomas, Springfield, Illinois.

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