Intro to Eye Path Flashcards by Meghan May

Eye Pathology: ITMIINDIO:

Inborn errors, Trauma, Meds, Infection, Ischemia, Neoplasm, Degeneration/age, Immune dyregulation, Other organ system

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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)

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What makes up teh function eye assement

 Visual acuity

 Visual fields

 Pupil exam

 Extraocular movements

 Intraocular pressure

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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

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indentify anatomy of cornea

key: transparent cover of teh eye or the ‘window”

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What are the layers of the cornea

Epithelium: protection and replicates

Bowmans

Stroma (acellular so light passes)

Descements

Endothelium

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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

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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

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What is the funtion of the retina

Fnx: let light to retina/ refractive thus bends rays to retina/ global to maintain shape eye

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 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

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characterized by central corneal opacity with iridocorneal adhesions

Peters type I

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central corneal opacity and cataracts or corneolenticular adhesions

Peters II

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Peters anomaly and short stature, developmental delay, dysmorphic facial features including cleft lip/palate along with cardiac and genital abnormalities

Peters-plus syndrome

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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

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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

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DDx for corneal opacity in newborn

Peters anomaly, Forceps delivery or Non-accidental trauma , TORCH infections

Metabolic disorders: Mucopolysaccharidoses or Sphingolipidoses

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How does the cornea respond to injury

Epithelial cell injury and death

Disruption of Bowman’s layer and stromal lamellae

Keratocyte injury and death

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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

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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

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Fuch’s corneal dystrophy

 ______ corneal dystrophy, more common in _____

 Affects vision starting in the ____

Autosomal dominant

women

50s

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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

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 Thickened stroma with fluid-filled spaces

 Cysts in epithelium
 Hazy cornea

Fuchs dystrophy

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Transparent biconvex structure
Located behind the pupil, attached in place by the zonule

lens

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Three main parts of lens

lens epithilum, lens capsule, lens fiber cells

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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