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Questions and Answers
What vitreous attachment could most likely cause a retinal tear?
What vitreous attachment could most likely cause a retinal tear?
- Optic disc
- Macula
- Vitreous base (correct)
- Posterior lens
Where are hyalocytes located in the vitreous chamber?
Where are hyalocytes located in the vitreous chamber?
- At the cortex near the vitreal surface (correct)
- Around the lens patellar fossa
- Within the collagen fibrils
- At the center of the anterior surface
What percentage of the vitreous is composed of water?
What percentage of the vitreous is composed of water?
- 97.5-98.0%
- 96.7-98.5%
- 98.5-99.7% (correct)
- 96.7-98.2%
Which is not considered a component of the vitreous?
Which is not considered a component of the vitreous?
As we age, the vitreous becomes more jelly like.
As we age, the vitreous becomes more jelly like.
What is the space between the posterior surface of lens and the vitreous?
What is the space between the posterior surface of lens and the vitreous?
The Cloquet's canal is remnants of the secondary vitreous.
The Cloquet's canal is remnants of the secondary vitreous.
Which is not correct regarding the functions of the vitreous
Which is not correct regarding the functions of the vitreous
What clinical application is due to a vitreous detachment near the optic nerve?
What clinical application is due to a vitreous detachment near the optic nerve?
The appearance of asteroid hyalosis is due to accumulation of calcium in the vitreous.
The appearance of asteroid hyalosis is due to accumulation of calcium in the vitreous.
Synchysis scintillants is the presence of cholesterol crystals in younger patients and occurs unilateral.
Synchysis scintillants is the presence of cholesterol crystals in younger patients and occurs unilateral.
At what time frame does the layer of Chievitz separate from inner and outer neuroblastic layers of primary retina?
At what time frame does the layer of Chievitz separate from inner and outer neuroblastic layers of primary retina?
What cells are NOT differentiated from the innermost layer of Chievitz?
What cells are NOT differentiated from the innermost layer of Chievitz?
Which cells are not differentiated from the outer layer of Chievitz?
Which cells are not differentiated from the outer layer of Chievitz?
Which retinal layer eventually develops from the layer of Cheivitz?
Which retinal layer eventually develops from the layer of Cheivitz?
What is the correct time frame for the normal retinal vascular development to occur?
What is the correct time frame for the normal retinal vascular development to occur?
What layer of the retina in a newborn is thinner but still has synapses established?
What layer of the retina in a newborn is thinner but still has synapses established?
During macula development, the cones synapse with cells from inner nuclear layer to form what layer?
During macula development, the cones synapse with cells from inner nuclear layer to form what layer?
What is the space between the neural retina and the RPE?
What is the space between the neural retina and the RPE?
What part of a photoreceptor cell that takes place in photo pigmentation?
What part of a photoreceptor cell that takes place in photo pigmentation?
What area does metabolic activity and photopigment synthesis occur on a photoreceptor cell?
What area does metabolic activity and photopigment synthesis occur on a photoreceptor cell?
The outer layer of the inner segment of a photoreceptor cell is called the myoid.
The outer layer of the inner segment of a photoreceptor cell is called the myoid.
The myoid region of a photoreceptor cell is the location of protein synthesis.
The myoid region of a photoreceptor cell is the location of protein synthesis.
Rods are used to detect objects in low levels of illumination.
Rods are used to detect objects in low levels of illumination.
Rod discs contain rhodopsin, that absorb protons maximally at what wavelength?
Rod discs contain rhodopsin, that absorb protons maximally at what wavelength?
Cones are used in photopic vision.
Cones are used in photopic vision.
What is the correct wavelength and color that correspond to short, medium, and long cones?
What is the correct wavelength and color that correspond to short, medium, and long cones?
Which retinal layer acts as a barrier for large metabolites and contains desmosomal attachments between Muller and photoreceptor cells?
Which retinal layer acts as a barrier for large metabolites and contains desmosomal attachments between Muller and photoreceptor cells?
What retinal layer contains cell bodies of rods and cones?
What retinal layer contains cell bodies of rods and cones?
What is the only layer of the retina that received blood supply from the choroid and the central retinal artery?
What is the only layer of the retina that received blood supply from the choroid and the central retinal artery?
What cells do the photoreceptor cells synapse with in the outer plexiform layer?
What cells do the photoreceptor cells synapse with in the outer plexiform layer?
The synaptic area of a rod is called a pedicle.
The synaptic area of a rod is called a pedicle.
What cell bodies are found in the inner nuclear layer?
What cell bodies are found in the inner nuclear layer?
How do horizontal cells modify the information that reaches the bipolar cells?
How do horizontal cells modify the information that reaches the bipolar cells?
What layer of the retina is the location for the synapses between the second and third order neurons in visual pathway?
What layer of the retina is the location for the synapses between the second and third order neurons in visual pathway?
What cells modify the synapses between ganglion and bipolar cells?
What cells modify the synapses between ganglion and bipolar cells?
Bipolar cells increase stimulation of ganglion cells.
Bipolar cells increase stimulation of ganglion cells.
Amacrine cells increase stimulation of ganglion cells.
Amacrine cells increase stimulation of ganglion cells.
What is the thickness of the ganglion cell layer in the macular region?
What is the thickness of the ganglion cell layer in the macular region?
Where do each ganglion cell axons terminate at?
Where do each ganglion cell axons terminate at?
Midget cells are sensitive to dim changes in illumination.
Midget cells are sensitive to dim changes in illumination.
Magnocellular cells are sensitive to dim changes in illumination.
Magnocellular cells are sensitive to dim changes in illumination.
Which retinal layer is not present in the fovea?
Which retinal layer is not present in the fovea?
Which retinal layer is absent over the optic disc?
Which retinal layer is absent over the optic disc?
Which neuroglial cell has the main function of glycogen metabolism?
Which neuroglial cell has the main function of glycogen metabolism?
Which retinal layer does not receive blood from the choroid via the short posterior ciliary arteries?
Which retinal layer does not receive blood from the choroid via the short posterior ciliary arteries?
Which retinal layer received blood from the superficial capillary networks of the CRA?
Which retinal layer received blood from the superficial capillary networks of the CRA?
Which retinal artery can allow the macula to be spared in a CRAO?
Which retinal artery can allow the macula to be spared in a CRAO?
Which is NOT true regarding xanthophyll pigments in the macula?
Which is NOT true regarding xanthophyll pigments in the macula?
What is the correct diameter of the fovea?
What is the correct diameter of the fovea?
What part of the macula has the highest concentration of cones?
What part of the macula has the highest concentration of cones?
Which part of the macula contains largest amount of bipolar and ganglion cells?
Which part of the macula contains largest amount of bipolar and ganglion cells?
The neural retina continues forward as the pigmented epithelium of the ciliary body.
The neural retina continues forward as the pigmented epithelium of the ciliary body.
What is the function of the A2E substance identified in lipofuscin accumulation?
What is the function of the A2E substance identified in lipofuscin accumulation?
Which type of vision does vitamin A, metabolized and stored by RPE cells, primarily support?
Which type of vision does vitamin A, metabolized and stored by RPE cells, primarily support?
What is the product of anaerobic metabolism in the RPE?
What is the product of anaerobic metabolism in the RPE?
What is the vitamin A called that is stored in the RPE and used for disc renewal?
What is the vitamin A called that is stored in the RPE and used for disc renewal?
Which growth factor, produced by the RPE, helps maintain choriocapillaries function?
Which growth factor, produced by the RPE, helps maintain choriocapillaries function?
What retinal disease is associated with the degeneration of photoreceptors?
What retinal disease is associated with the degeneration of photoreceptors?
What is responsible for maintaining the slight negative electrical charge in photoreceptors during darkness?
What is responsible for maintaining the slight negative electrical charge in photoreceptors during darkness?
At what voltage is the electrical charge maintained in photoreceptors in the dark?
At what voltage is the electrical charge maintained in photoreceptors in the dark?
Which cells are activated first by the hyperpolarization of photoreceptors during phototransduction?
Which cells are activated first by the hyperpolarization of photoreceptors during phototransduction?
What triggers the start of vision in the phototransduction process?
What triggers the start of vision in the phototransduction process?
What is the role of cyclic GMP-gated channels in photoreceptors?
What is the role of cyclic GMP-gated channels in photoreceptors?
Which protein determines the wavelength absorption in the visual pigments?
Which protein determines the wavelength absorption in the visual pigments?
What allows for electrical synapses to pass directly between cells in the retina?
What allows for electrical synapses to pass directly between cells in the retina?
Which transporter is responsible for moving lactate across the RPE, a product of anaerobic metabolism?
Which transporter is responsible for moving lactate across the RPE, a product of anaerobic metabolism?
What is the significance of aquaporins in the physiology of the RPE cells?
What is the significance of aquaporins in the physiology of the RPE cells?
Which family of glucose transporters is mainly utilized in the retina for glucose transport?
Which family of glucose transporters is mainly utilized in the retina for glucose transport?
What is the primary function of the retinal pigment epithelium (RPE) in maintaining the health of the choriocapillaris?
What is the primary function of the retinal pigment epithelium (RPE) in maintaining the health of the choriocapillaris?
What is the primary function of the pigment granules within the RPE cells?
What is the primary function of the pigment granules within the RPE cells?
Which of the following statements about the relationship between the RPE and photoreceptors is correct?
Which of the following statements about the relationship between the RPE and photoreceptors is correct?
What is the primary function of the gap junctions in the retina?
What is the primary function of the gap junctions in the retina?
Which of the following neurotransmitters is excitatory in the retina?
Which of the following neurotransmitters is excitatory in the retina?
What is the primary function of the RPE in the visual cycle?
What is the primary function of the RPE in the visual cycle?
Which of the following statements about the shedding of photoreceptor outer segments is correct?
Which of the following statements about the shedding of photoreceptor outer segments is correct?
Which cell is not considered an excitatory cell in the retina?
Which cell is not considered an excitatory cell in the retina?
Which retinal cells are considered to be inhibitory, that release GABA and Glycine?
Which retinal cells are considered to be inhibitory, that release GABA and Glycine?
Which of the following proteins is responsible for transporting all-trans retinol from the photoreceptor to the RPE?
Which of the following proteins is responsible for transporting all-trans retinol from the photoreceptor to the RPE?
During dark photo transduction, what is released from the depolarized photoreceptors?
During dark photo transduction, what is released from the depolarized photoreceptors?
Which type of retinal cells are responsible for the center-surround organization of receptive fields?
Which type of retinal cells are responsible for the center-surround organization of receptive fields?
What is the primary function of horizontal cells in the retina?
What is the primary function of horizontal cells in the retina?
What is the primary mechanism by which ON-center bipolar cells respond to light stimulation?
What is the primary mechanism by which ON-center bipolar cells respond to light stimulation?
What does the RPE convert all-trans-retinol to?
What does the RPE convert all-trans-retinol to?
Which type of retinal cells are responsible for relaying visual information to the lateral geniculate nucleus (LGN) of the thalamus?
Which type of retinal cells are responsible for relaying visual information to the lateral geniculate nucleus (LGN) of the thalamus?
Which type of retinal cells are responsible for modulating the synaptic connections between bipolar cells and ganglion cells?
Which type of retinal cells are responsible for modulating the synaptic connections between bipolar cells and ganglion cells?
What is the primary function of Müller cells in the retina?
What is the primary function of Müller cells in the retina?
In a dark response, the photoreceptor is hyperpolarized.
In a dark response, the photoreceptor is hyperpolarized.
Light adaptation can take up to 30 minutes for retina to adapt.
Light adaptation can take up to 30 minutes for retina to adapt.
Exposure to 400-500 nm light at night can disrupt circadian rhythm.
Exposure to 400-500 nm light at night can disrupt circadian rhythm.
The pituitary gland releases melatonin, which is important for circadian rhythm.
The pituitary gland releases melatonin, which is important for circadian rhythm.
Glutamate is released in a light response.
Glutamate is released in a light response.
What is not a treatment regimen for a retinal detachment?
What is not a treatment regimen for a retinal detachment?
What retinal layer will you find flame-shaped hemorrhages?
What retinal layer will you find flame-shaped hemorrhages?
What type of hemorrhage involves the rupture of deep capillaries?
What type of hemorrhage involves the rupture of deep capillaries?
Which is NOT a systemic condition that causes boat hemorrhages?
Which is NOT a systemic condition that causes boat hemorrhages?
What retinal layer will you find hard exudates?
What retinal layer will you find hard exudates?
What condition is not associated with cotton wool spots?
What condition is not associated with cotton wool spots?
What retinal application is associated with metabolic debris from RPE?
What retinal application is associated with metabolic debris from RPE?
What is not as associated cause of Hollenhurst plaques?
What is not as associated cause of Hollenhurst plaques?
What are some conditions that present with retinal vasculitis?
What are some conditions that present with retinal vasculitis?
What ocular condition is secondary to an increase in intracranial pressure?
What ocular condition is secondary to an increase in intracranial pressure?
Optic disc edema is usually presented unilaterally.
Optic disc edema is usually presented unilaterally.
What type of macular degeneration presents with acute sub-retinal blood in macular region with subtle sub-retinal fluid and is not presented with choroidal neovascular membrane?
What type of macular degeneration presents with acute sub-retinal blood in macular region with subtle sub-retinal fluid and is not presented with choroidal neovascular membrane?
Dry age-related macular degeneration is also called exudative degeneration.
Dry age-related macular degeneration is also called exudative degeneration.
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Study Notes
RPE Cells in Retinal Physiology
- RPE cells phagocytose fragments from the continual shedding of the photoreceptor outer segment discs, which accumulates as lipofuscin.
- Lipofuscin, a yellow-brown pigment, contains lipid-containing residues of lysosomal digestion and contributes to RPE cell death.
- RPE cells metabolize and store vitamin A, which is essential for the biochemical process in the rod disc renewal system.
- Vitamin A is also known as all-transretinol, and it helps in night vision as a precursor of rhodopsin.
- RPE cells contribute to the formation of the interphotoreceptor matrix (IPM) between the RPE layer and the photoreceptors.
- The IPM is composed of hyaluronan (HA), which forms a basic scaffold structure, and interacts with HA-binding motifs on cells that border the IPM.
RPE Functions
- RPE cells are fundamental to the health of the neural retina and the choriocapillaris.
- They form a part of the blood-retinal barrier, which isolates the inner retina from systemic influences.
- RPE cells electively control the movement of nutrients and metabolites from the choriocapillaris into the retina and removal of waste products.
- Water is eliminated from the subretinal space by active transport through the RPE, involving ion pumps, exchangers, and channels.
- Glucose transporters in the RPE cells maintain a steady supply of glucose to the active photoreceptors.
- RPE cells produce growth factors that drive certain cellular processes, including vascular endothelial growth factor (VEGF) and pigmented epithelial-derived factor (PEDF).
Photoreceptors
- The relationship between the RPE and photoreceptors is reciprocal, and dysfunction in one layer affects the other.
- Retinal degenerative diseases often cause changes in the RPE that are clinically visible.
- Photoreceptors have different types of vision, including scotopic vision (rod-dominated, low light levels) and photopic vision (cone-dominated, high light levels).
- The composition of visual pigments includes opsins and chromophores, which determine the wavelength absorption of light.
Visual Pigments
- Cones have three photopigments, differing in amino acid composition, which are sensitive to different wavelengths of light (red, green, and blue).
- Rods have a single photopigment, rhodopsin, which is sensitive to low light levels.
- The formation of visual pigments involves the conversion of 11-cis retinal to all-trans retinal, which is moved into the cytoplasm and reduced to all-trans retinol.
Retinal Synapses
- Information transmission between retinal neurons occurs through ion channel activity at gap junctions and chemical synapses.
- Neurotransmitters, such as glutamate, GABA, and glycine, and neuromodulators, like dopamine and cGMP, play a crucial role in retinal transmission.
Phototransduction
- Phototransduction is the process by which light is converted into an electrical signal in photoreceptors.
- The absorption of light triggers a series of biochemical changes, leading to the hyperpolarization of the photoreceptor and the transmission of the signal to other retinal neurons.
Retinal Cells
- Bipolar cells have center-surround receptive fields, responding to spatial antagonism.
- Horizontal cells receive input from a large number of photoreceptors, contributing to spatial summation.
- Ganglion cells are activated by the signal from bipolar cells and transmit the message to the brain.
Vitreous Humor
- The vitreous humor is a gel-like substance that fills the vitreous chamber, making up 80% of the eye's volume.
- Its components include 98.5% to 99.7% water, collagen fibers, and hyaluronic acid.
- The vitreous humor undergoes changes with age, becoming more liquid and forming pockets of fluid.
- Vitreous attachments, including the vitreous base, posterior lens, optic disc, macula, and annular ring, are important for maintaining the integrity of the retina.
Vitreous Changes
- Age-related changes in the vitreous humor include the formation of floaters, aggregation of collagen fibrils, and the formation of pockets of fluid.
- Vitreous detachments, including posterior vitreous detachment, can occur due to trauma, age, or other factors.
- Clinical applications of vitreous changes include the diagnosis of vitreous hemorrhage, neovascularization, and retinal detachment.
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