Intro to Eye Path Flashcards
Eye Pathology: ITMIINDIO:
Inborn errors, Trauma, Meds, Infection, Ischemia, Neoplasm, Degeneration/age, Immune dyregulation, Other organ system
What makes up the Vital signs of the visual system
Comprehesive eye exam: Visual actuity, visual fields, pupil exam, extraoccular mvmt, intraocular pressure, exam ocular adnex +antoer segment structures + fundus exam (anatomical assessment)
What makes up teh function eye assement
Visual acuity
Visual fields
Pupil exam
Extraocular movements
Intraocular pressure
You are looking at eye that is glassy on 2 day old baby, follows light, attracted to ligt in all 4 quads has round pupil R in rt eye with normal red reflex
in Left eye there is no red reflex and lack of pupillary reaciton, next step
Exam under anesthesia
check Intraocular pressure/ Corneal diameter/thickness
Ultrasound of anterior and posterior segments/ Refraction/retinoscopy and Dilated fundus exam
indentify anatomy of cornea
key: transparent cover of teh eye or the ‘window”
What are the layers of the cornea
Epithelium: protection and replicates
Bowmans
Stroma (acellular so light passes)
Descements
Endothelium
Anatomy of cornea:
Made of parallel fibers of _______and keratocytes (special fibroblasts).
Needs_____ structure to maintain optical clarity (not to interfere with light coming into the eye).
type 1 collagen
parallel
Cornea:
Absence of____ (to not disturb the parallel fibers).
O2 and nutrients obtained through___ anteriorly and _____ posteriorly.
Layer of _______ to continually pump out fluid from inside to maintain relatively dehydrated structure.
vessels
tears
aqueous humor
endothelial cells
What is the funtion of the retina
Fnx: let light to retina/ refractive thus bends rays to retina/ global to maintain shape eye
Rare eye malformation resulting in congenital corneal opacity
Part of a spectrum of developmental anomalies of the cornea, iris and lens termed “anterior segment dysgenesis.”
Peters anomaly
characterized by central corneal opacity with iridocorneal adhesions
Peters type I
central corneal opacity and cataracts or corneolenticular adhesions
Peters II
Peters anomaly and short stature, developmental delay, dysmorphic facial features including cleft lip/palate along with cardiac and genital abnormalities
Peters-plus syndrome
Peters anomaly has a wide spectrum of severity. Sporadic or genetic in the ___ gene
Corneal opacification is bilateral in approximately 80% of cases
PAX6 gene
What is teh pathological issue in Peter’s anamoly
The endothelium and Descemet’s membrane do not form correctly (fluid is not removed from that cornea efficiently) – opacity
Corneal collagen fibers are disturbed in that area - opacity
DDx for corneal opacity in newborn
Peters anomaly, Forceps delivery or Non-accidental trauma , TORCH infections
Metabolic disorders: Mucopolysaccharidoses or Sphingolipidoses
How does the cornea respond to injury
Epithelial cell injury and death
Disruption of Bowman’s layer and stromal lamellae
Keratocyte injury and death
MOre info on corneal repair;
Epithelial hyperplasia Stromal contraction Epithelial repair
Keratocyte activation Synthesis of type I collagen, keratan sulfate and type VI collagen
Blood vessel formation Keratocyte apoptosis Blood vessel apoptosis
Why do we get corneal scars with traum adn risk losing clarity
bc shit grows in, try to repari and resport type I collegens adn keratocytes, but at the end they apoptos to ensure clarity and insread scar d/t lack of parellel structure
Fuch’s corneal dystrophy
______ corneal dystrophy, more common in _____
Affects vision starting in the ____
Autosomal dominant
women
50s
Dysfunction of corneal endothelial cells with growth of Descemet’s membrane “bumps”, called gutttae.
In end stage of disease there is loss of endothelial cell
Fuchs corneal dystrophy
Thickened stroma with fluid-filled spaces
Cysts in epithelium
Hazy cornea
Fuchs dystrophy
Transparent biconvex structure
Located behind the pupil, attached in place by the zonule
lens
Three main parts of lens
lens epithilum, lens capsule, lens fiber cells
lens fibers cells are
Long, thin, transparent cells
Arrange intracellular content and dispose of unnecessary organelles
Functions of the lens
Transparency- let light reach the retina
Refractive structure/accommodation- bend rays to reach the retina
Lens is flexible – by changing the curvature of the lens one can focus for distance, intermediate or nea
Caused by maternal infection by RNA toga virus Infection of lens fiber cells by virus
What would be result of viral infection of lens fiber cells
disorganization of lens intraocular organelles and opacification of lens fibers
What happens when Rubella infects lens fibers
Lens cells retain nucleus and organelles
Pearly white focal nuclear opacification
Can progress to complete cataract
Live virus can be recovered from lens up to 3yrs after birth
“Salt and pepper” appearance
Due to damage of the retina pigmented epithelium layer
Vision, in most instances is preserved
Rubellar retinopathy
Triad seen in congenital rubella infection
Sensorineural deafness
Eye abnormalities (70% of pts)
Congenital heart disease
Anatomy of retina and funx
Layer of eye that converts light–> neuronal impulse
nourishes and supports photoRs, absorbs scat light, supply nutrient, BBR layer, participate in visual cycle, phatocytosis of photoR in outer segment
Fnx retinal pigmented epithelium:
Function of the photoreceptors:
specialized neuron that converts light into neuronal signal
Transmit information to the brain (thalamus, hypothalamus and midbrain
inner plexiform layer
Houses the bipolar, horizontal and amacrine cells
inner nuclear layer
Contains the cell bodies of the rods and cones photoreceptors
Outer nuclear layer
see these bone spicules in retina with pale reitna
Retinitis pigmentossa
Most common form of inherited retinal degeneration.
Caused by abnormalities in photoreceptors (rods and cones) or the retinal pigmented epithelium.
Retinitis Pigmentosa
15% of retinitis pigmentosa d/t
mutation in rhodopsin
Light sensitive receptor protein found in rod photoreceptors
Composed of the protein opsin and the cofactor chromophore retinal
Rhodopsin
Retinol is produced in the retina from ____
Isomerization of _____ to ______by light changes the shape of the opsin activating a G-protein cascade
In addition to rhodopsin there are four other____ found in the cone cells
Vitamin A
11-cis-retinal to all-trans-retinal
opsins
15% of all RP are due to a mutation in_____.
The mutations usually cause misfolding of the____ protein.; this leads to faulty outer rod segment recycling.
rhodopsin
opsin
Mutations in 35 other genes that encode for proteins needed for the visual transduction cascade can cause RP. Some of these mutated genes encode for a
pre-mRNA splicing factor expressed in all cells.
Why would mutations that would affect all cells in the body cause retinitis pigmentosa?
The photoreceptors are very metabolically active and would be affected more than other cells.
Inherited AD, AR and X-linked (dominant or recessive).
3 types:
Non-syndromic
Syndromic (ex. combined with deafness – Usher syndrome)
Secondary to other systemic diseases (ex.Refsum’s disease- abnormal build up of phytanic acid, a type of fatty acid)
Other retinal degenerations seen:
There are more than 30 other retinal degenerations/dystrophy caused by a dysfunction of one or more of the retinal cells
Degeneration of the retinal pigmented epithelium
Accumulation of drusen excrescences believed to represent byproducts of vision
Age-related macular degeneration : see drusen
Differnce btwn Dry and Wet macular degeneration
Dry macular degeneration – progressive accumulation of druse
In wet age-related macular degeneration, blood vessels from the choroidal layer invade the disrupted Bruch’s membrane causing bleeding in the outer layers of the retina.
Disruption of normal retina architecture then leads to loss of photoreceptors and retinal pigmented epithelium.
In wet age-related macular degeneration, blood vessels from the _____ invade the disrupted Bruch’s membrane causing bleeding in the_____of the retina.
Disruption of normal retina architecture then leads to loss of ____ and _____
choroidal layer
outer layers
photoreceptors and retinal pigmented epithelium.
IN macular degeneration, Eventually, loss of retinal pigmentation epithelium causes loss of
photoreceptors
Abnormal development of the vasculature of the retina in babies born pre-term.
Increase risk if
born <1250 grams or earlier than 31 weeks.
Posterior circulation: blood from the____ feeds the posterior 1/3 of the retina
Anterior circulation: blood from the ______ feeds the anterior 1/3 of the retina
choroid
central retinal artery
Baby born prior to full retinal vascular maturation.
Factors associated with birth and leaving the womb result in :
Vessels and retina become:
halting of normal vascular migration to the peripheral retina.
abnormal (forming ridges, vessels growing towards the vitreous)
What happens to untreated premature retinopathy?
How do you treat it?
If untreated, retina will detach.
Untreated retinal detachment causes blindness in baby.
Laser or VEGF
Leading cause of blindness for people aged 20 to 64 years
Retinal dysfunction due to hyperglycemia
Pericyte loss in retinal capillaries
Weak vessels bleed in the retina
Diabetic retinopathy
Hyperglycemia causes ___ loss in retinal capillaries and Weak vessels bleed in the___
Pericyte
retina
Development of vascular abnormalities and bleeding:
Microaneurysms
Dot-blot hemorrhages
Flame hemorrhages
seen in diabetic retinal neuraopathy
In diabetic retinal neurapapthy: Underperfused retina secretes ________ thus
Abnormal blood vessels grow towards the_____ and over other structures. Fragile blood vessels bleed.
Contraction of the abnormal vasculature pulls the retina causing _____
vascular endothelial growth factor
vitreous
retinal detachment
Lack of blood flow through the central retinal artery.
Causes include atherosclerosis of the carotid artery or embolism
see cherry red spot
Central retinal artery occulsion
Causes of central retinal artery occlusion
Causes include atherosclerosis of the carotid artery or embolism
Outcomes for pts with CRAO
Patients with visualized retinal artery emboli have a 56% mortality rate over 9 years, compared to 27% for an age- matched population without retinal artery emboli. Life expectancy of patients with CRAO is 5.5.
Central retinal artery occlusion resluts in loss of
Loss of the inner retina
Cancer of the immature retinal cells
Most common malignant tumor of the eye in children
2 forms: 55% non-heritable (new mutation) and heritable (familial gene)
Retinoblastoma
Bilateral retinoblastoma are usually_____, unilateral can be _____
Inheritance is _______
heritable
non-heritable
AD (90% penetrance)
Retinoblastoma: Mutation in _______(tumor suppressor protein that prevents excessive cell growth)
Ch 13 on the RB1 gene (
You see this on histology of someones eyeball
Flexner-Wintersteiner rosettes in retinoblastoma
Optic nerve or _____; transfer ocular neuronal impulses to the brain
Cranial nerve 2
The optic nerve is composed of the axons of the _______
Contains approximately 1 million nerve fibers that end at the _______
retinal ganglion cells (and glial cells).
lateral geniculate nucleus
Funtion of optic nerve
The optic nerve transmits sensory information regarding brightness and contrast perception (visual acuity), color perception and visual field information. It also transmits the fibers that control pupillary response
Describe traumatic optic neuropathy
Direct or indirect injury (transmitted shock from orbital impact) to the optic nerve results in traumatic optic neuropathy
Common mechanisms of injury include motor vehicle accident, bike accident, fall and assault.
As a result of traumatic optic neuropathy:_____ loss appears to occur either through direct trauma, hemorrhagic infarction, direct compression of the nerve fibers from an extrinsic nerve sheath hematoma, shearing forces, or a combination of these mechanisms.
Loss of_____ support appears to occur followed by replacement of the axons with____.
Axonal
astrocyte
microglia
Progressive optic neuropathy due to slow loss of optic nerve fibers
glaucoma
Risk factors for glaucoma, which is modifiable
Intraocular pressure ***** modifiable
Age
Central cornealt hickness
Race
