Vitreous
The vitreous is composed of what types of collagen?
Primarily type II
IX shield type II fibrils and prevent them from fusing
V/XI located in the core of collagen fibers participate in fiber formation
Light induces ____polarization, leading to a cascade of reactions called phototransduction
hyperpolarization
What test can be used to distinguish Best disease from other conditions causing vitelliform lesions in the retina?
Electro-oculogram (EOG)
Describe how some females have tetravariant color vision
Most color vision abnormalities are caused by unequal crossing over between the L- and M-cone opsin genes. This inequality creates hybrid opsins that have different spectral absorption functions. Some males have a serine-to-alanine substitution at amino acid 108 on the cone opsin gene, which allows more sensitivity to red light. Females with both the serine-containing and the alanine-containing opsins can have tetravariant color vision.
Who's that resident?
(2)
Dr. Sadat
What physiologic change after vitrectomy leads to the development of cataract?
A 23-year-old athletic male complains of decreased vision in the upper visual field of his left eye. Examination reveals a retinal dialysis from 4 to 6:30 o'clock associated with a shallow inferior retinal detachment just posterior to the equator. What is the preferred treatment?
A. Observe.
B. Schedule vitrectomy, internal drainage, laser demarcation, and C3F8 gas injection for the next available time.
C. Perform emergent vitrectomy, internal drainage, laser demarcation, and C3F8 gas injection.
D. Schedule a scleral buckle procedure for the next available time.
D -
Retinal detachments associated with retinal dialyses have very high reattachment rates with scleral buckle procedures. When performed in the absence of a pars plana vitrectomy, scleral buckle procedures utilize retinal cryopexy to create chorioretinal adhesions around any retinal breaks, with or without external drainage of subretinal fluid. This approach has the advantage of avoiding the need for a gas bubble which would promote cataractogenesis in this young phakic patient.
In the event that vitrectomy, laser, and gas injection were considered, a shorter duration gas such as SF6 would be preferred, to avoid prolonged need for eye down positioning. Vitrectomy is the preferred surgical option, over scleral buckle with retinal cryopexy, in cases with giant retinal tears, proliferative vitreoretinopathy, poorly defined breaks, or pseudophakic patients in whom it is uncertain that all breaks have been identified. Observation of a symptomatic retinal detachment is contraindicated.
What is a function of the RPE?
A phagocytosis of photoreceptor outer segments
B maintenance of the inner blood retinal barrier
C reflection of light
D vitamin D metabolism
A
Describe how some females have tetravariant color vision
Most color vision abnormalities are caused by unequal crossing over between the L- and M-cone opsin genes. This inequality creates hybrid opsins that have different spectral absorption functions. Some males have a serine-to-alanine substitution at amino acid 108 on the cone opsin gene, which allows more sensitivity to red light. Females with both the serine-containing and the alanine-containing opsins can have tetravariant color vision.
If you see this, where are you?
(3)
At the VA
The potential space between the posterior lens capsule and the anterior hyaloid membrane. Also the reason you don't need to pull out your vitrector after biting the posterior capsule and can go home on time.
Berger's space
The Early Treatment of Diabetic Retinopathy Study (ETDRS) identified patients at greatest risk to develop proliferative diabetic retinopathy (PDR) by what findings?
A. Severe intraretinal hemorrhages in one quadrant
B. Hard exudate 1500 um from the center of the macula
C. Moderate IRMA in one or more quadrants
D. Venous beading in 1 quadrant
Severe intraretinal hemorrhages (typically estimated as >20) and microaneurysms in 4 quadrants
Definite venous beading in 2 or more quadrants
Moderate IRMA in 1 or more quadrants
What is the maximum daily dose of hydroxychloroquine that is recommended to minimize the risk of retinopathy?
5.0 mg/kg/day using total body mass
What are 3 proposed mechanisms behind the pathophysiology of UVLASOR?
Unexplained visual loss after SO removal (UVLASOR) is a sight-threatening complication following vitreoretinal surgery.
- May be due to bright light from OR microscope inducing retinal phototoxicity
- SO tamponade may directly traumatize the inner retina
- The reduced volume of distribution of a SO filled eye may play a role in the sequestration of cytokines or other pro-inflammatory agents
- High fibrogenic growth factors and cytokines like IL-6 in the retro-oil fluid create a fibrocellular membrane that can alter retinal layers
Who's that resident?
(1)
Dr. Mahmud
A 2-week-old infant with leukocoria presents with suspected persistent fetal vasculature (PFV). Anatomically, what globe size strongly supports a diagnosis of PFV over retinoblastoma?
A. normal axial length
B. nanophthalmos
C. microphthalmia
D. buphthalmos
C - Persistent fetal vasculature (PFV) results from the failure of the fetal hyaloid vascular complex to regress and is almost always unilateral. Clinically, a retrolental membrane of varying size and density is attached to the posterior lens surface. In contrast to retinoblastoma, which typically occurs in normal-sized eyes, these eyes are nearly always microphthalmic (small and disorganized globe) to some degree. Nanophthalmos refers to small eyes (axial length < 18 mm ) that have a high lens-to-anterior segment ratio but otherwise lack disorganization. Buphthalmos ("ox eye") refers to diffuse globe enlargement, usually in the setting of congenital glaucoma.
What characteristic of the retina makes it more vulnerable to damage from lipid peroxidation?
A. high levels of saturated fatty acids in the rod outer segments
B. poor oxygen supply through the choroid
C. low light exposure at night
D. high number of mitochondria in the rod inner segments
D - The retina has several distinctive characteristics that make it vulnerable to damage from lipid peroxidation. (1) Rod inner segments are rich in mitochondria, which may leak activated oxygen species. (2) Rod outer segments possess high levels of polyunsaturated fatty acids (PUFAs), making them susceptible to damage by oxygen. PUFAs are sensitive to peroxidation in proportion to their number of double bonds. (3) The abundant oxygen supply through the choroid and retinal vessels elevates the risk of oxidative damage. (4) There are many chromophores in the outer retina. Light exposure may trigger photooxidative processes mediated by singlet oxygen, and the RPE may play a key role.
A 2-year-old girl was brought to the clinic by her mother, who explained that the child had "wandering eyes." During the visit, the patient often poked her eyes with her fingers. The examination showed poorly reactive pupils. Electroretinography revealed extinguished rod and cone responses. What gene mutation is most likely associated with this condition?
RPE65
Give the complete pathway involved in Vitamin A regeneration, beginning with light-induced activation of rhodopsin.
Light-induced activation of rhodopsin leads to isomerization of 11-cis-retinal to all-trans-retinal which is freed from rhodopsin to undergo the retinoid cycle.
Free all-trans-retinal is cleared from the rod discs by ABCA4 to the cytosol of the outer segments.
All-trans-retinal is enzymatically reduced to all-trans-retinol by retinol dehydrogenase.
It then binds interphotoreceptor retinoid-binding protein (IRBP) in the interphotoreceptor matrix.
RPE cellular retinol-binding protein 1 (CRBP1) promotes uptake of all-trans-retinol, afterwhich the molecule is esterified be lecithin retinol acyltransferase (LRAT).
The resultant retinyl ester is hydrolyzed and isomerized to the 11-cis configuration by retinoid isomerohydrolase RPE65.
11-cis-retinol is oxidized to 11-cis-retinal and released by RPE cells, inevitably transported back to the photoreceptor outer-segment discs by IRBP to generate another visual transduction cycle.
(Some generation of vitamin A also occurs through uptake from the blood and phagocytosis of shed outer-segment discs)
A faint linear mark of semi-transparent residue on a 2W operating room chair
Frigoletto sign
What two adhesion molecules attach the vitreous to the internal limiting membrane (ILM) of the retinal surface?
A fibronectin and integrin
B fibronectin and laminin
C laminin and connectin
D fibronectin and connectin
B Fibronectin and laminin
A 2-year-old girl was brought to the clinic by her mother, who explained that the child had "wandering eyes." During the visit, the patient often poked her eyes with her fingers. The examination showed poorly reactive pupils. Electroretinography revealed extinguished rod and cone responses. What gene mutation is most likely associated with this condition?
RPE65
A patient reports lifelong poor night vision. The fundus examination reveals numerous yellow-white dots, sparing the fovea but scattered throughout the posterior pole and mid-periphery. An ERG shows undetectable rod signals after a standard 30 minutes of dark adaptation, but the signals normalize in 1 eye that undergoes overnight dark adaptation. What is the diagnosis?
A retinitis pigmentosa (RP) sine pigmento
B fundus albipunctatus
C fundus flavimaculatus
D retinitis punctata albescens
B Normalization of rod ERG responses with prolonged dark adaptation distinguishes the stationary condition fundus albipunctatus from retinitis punctata albescens. Both conditions are characterized by numerous retinal flecks, but retinitis punctata albescens is a progressive rod-cone dystrophy in which prolonged dark adaptation does not result in a full rescue of rod signals on ERG. Bone spicules may sometimes be absent in retinitis pigmentosa (RP sine pigmento), but the atrophic appearance of the peripheral retina and retinal pigment epithelium (RPE) still differs from the discrete retinal flecks of either fundus albipunctatus or retinitis punctata albescens. As with the latter diagnosis, the ERG in RP does not normalize with dark adaptation. Fundus flavimaculatus describes a Stargardt disease phenotype in which subretinal flecks are widely scattered throughout the fundus
Kyasanur Forest Disease Virus is a zoonotic disease caused by a single-stranded, positive-sense RNA arbovirus that is part of the Flavivirus genus. Ocular manifestations include keratitis, iritis, lenticular opacities and vitreous and intraretinal hemorrhages. Human transmission typically occurs through which vectors?
Bites from Haemophysalis spinigera ticks or through contact with sick or recently deceased monkeys
A magical learning experience that lands in your lap when a more senior, far-more-qualified colleague decides it’s the perfect time for a long lunch... and leaves you solo-dolo to diagnose the Nothnagel syndrome pt that was added on to your resident clinic. Often framed as “a great growth opportunity.” For you, not them.
Getting Guffey'd