Introduction to Ophthalmic Pathology Flashcards Preview

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Flashcards in Introduction to Ophthalmic Pathology Deck (23):
1

What are the common causes of eye pathology? (9)

  • "ITMIINDIO"
  • Inborn errors: congenital (dystrophies)
  • Trauma & healing
  • Medications & exposure
  • Infection
  • Ischemia & vascular insufficiency
  • Neoplasm
  • Degeneration, genetic or age-associated
  • Immune dysregulation
  • Other organ, system 

2

What are the steps of a comprehensive eye exam? 

  • “Vital signs of the visual system”
  • Functional assessment of the eye
    • Visual acuity
    • Visual fields
    • Pupil exam
    • Extraocular movements
    • Intraocular pressure
  • Anatomical assessment of the eye
    • Exam of the ocular adnexa & anterior segment structures
    • Pen light, slit lamp
    • Fundus examination 

3

The ______ is the transparent covering, or "window", of the eye. 

Cornea

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4

What are the 5 layers of the cornea

  • Epithelium (regenerates)
  • Bowman’s membrane
  • Stroma (acellular)
  • Descemet’s membrane
  • Endothelium 

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5

How is the cornea structurally organized? 

Are there vessels?

What is the role of the endothelial cells? 

  • Parallel fibers of type 1 collagen & keratocytes (special fibroblasts)
  • Needs parallel structure to maintain optical clarity
  • Not to interfere w/ light coming into the eye
    • Absence of vessels (to not disturb the parallel fibers)
  • O2 & nutrients obtained through tears anteriorly & aqueous humor posteriorly
  • Layer of endothelial cells to continually pump out fluid from inside to maintain relatively dehydrated structure

6

What are the 3 main functions of the cornea?

  • “Transparent window”
    • Let light reach the retina
  • Refractive structure
    • Bend rays to reach the retina
  • Mechanical structure  
    • As part of the globe to maintain integrity of the eye 

7

Peter's Anomaly

Definition

Inheritance

Severity 

  • Rare eye malformation resulting in congenital corneal opacity
  • Part of a spectrum of developmental anomalies of the cornea, iris & lens determined “anterior segment dysgenesis” 
  • Wide spectrum of severity
  • Sporadic or genetic (PAX6 gene)
  • Corneal opacification bilateral (80%) 

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8

Definitions/Differences

  • Peter's anomaly type I
  • Peter's anomaly type II
  • Peter's + syndrome 

  • Peter's anomaly type I
    • central corneal opacity
    • iridocorneal adhesions
  • Peter's anomaly type II
    • central corneal opacity
    • cataracts or corneolenticular adhesions
  • Peter's + syndrome 
    • Peter’s anomaly & short stature, developmental delay, dysmorphic facial features (cleft lip/palate), cardiac & genetic abnormalities 

9

How does Peter's Anomaly present histologically?

  • Endothelium & Descemet’s membrane don’t form correctly --> fluid is not removed from that cornea efficiently = opacity
  • Corneal collagen fibers disturbed in that area = opacity 

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10

Peter's Anomaly: Differential Diagnosis 

  • Congenital 
  • Traumatic 
  • Infection
  • Meds
  • Other systemic diseases 

  • Congenital 
    • Peter’s anomaly
    • Axenfeld-Rieger syndrome
    • Sclerocornea
    • CHED
    • CHSD
    • Glaucoma 
  • Traumatic 
    • Forceps delivery
    • Non-accidental trauma (abuse)
  • Infection
    • TORCH infections
  • Meds
    • Exposure to acid/base chemicals 
  • Other systemic diseases 
    • Metabolic disorders
    • Mucopolysaccharidoses
    • Sphingolipidoses 

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11

What is the corneal response to injury? (3)

  • Epithelial injury & death
  • Disruption of Bowman’s layer & stromal lamellae
  • Keratocyte injury & death 

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12

What are the steps of corneal repair? (8)

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  • Epithelial hyperplasia
  • Stromal contraction
  • Epithelial repair
  • Keratocyte activation
  • Synthesis of type I collagen, keratan sulfate & type IV collagen
  • Blood vessel formation
  • Keratocyte apoptosis
  • Blood vessel apoptosis

13

What is the end result of the corneal response to trauma? 

Corneal scar due to lack of parallel structure in the area of injury/repair 

14

Fuch's Corneal Dystrophy 

Definition

Epidemiology

End Stage 

  • Autosomal dominant corneal dystrophy
  • W > M
  • Affects vision starting in the 50s
  • Dysfunction of corneal endothelial cells w/ growth of Descemet’s membrane “bumps” (guttae)
  • End stage of disease = loss of endothelial cell 

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15

What is the pathological consequence of Fuch's Corneal Dystrophy?

How does this present microscopically/grossly?

Cornea will accumulate fluid in the stroma & epithelium

  • Thickened stroma w/ fluid-filled spaces
  • Cysts in epithelium
  • Hazy cornea

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16

What structure is being described?

Transparent biconvex structure
Located behind the pupil
Attached in place by the zonules 

Lens 

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17

What are the 3 main parts of the lens?

  • Lens epithelium
  • Lens capsule
  • Lens fiber cells
    • Long, thin, transparent cells
    • Arrange intracellular content & dispose of unnecessary organelles 

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18

What is the function 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 near 

19

Rubella Cataract

Definition

Effect on lens

Result 

  • Maternal infection by RNA toga virus
  • Infection of lens fiber cells by virus
    • Lens cells retain nucleus & organelles
    • Pearly white focal nuclear opacification
    • Can progress to complete cataract
    • Live virus can be recovered from lens up to 3 yrs after birth
  • Result: disorganization of the lens intraocular organelles & opacification of the lens fibers 

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20

What is this?

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Rubella Retinopathy 

  • “Salt & pepper” appearance
  • Damage of the retina pigmented epithelial layer
  • Vision in most instances is preserved 

21

Congenital Rubella Infection

Triad 

Other Manifestations

  • Triad
    • Sensorineural deafness
    • Eye abnormalities (70%)
    • Congenital heart disease
  • Other manifestations
    • Microcephaly
    • Hepatomegaly or other liver problems
    • Thrombocytopenia purpura or other bone marrow problems
    • Learning disability 

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22

Rubella Cataract: Differential Diagnosis

  • Congenital
  • Traumatic
  • Infection
  • Meds
  • Other systemic diseases 

  • Congenital
    • Familial genetic
    • Syndromic (Trisomy 21)
    • Eye dysgenesis
  • Traumatic
    • Forceps delivery
    • Non-accidental trauma (abuse)
  • Infection
    • TORCH infections
  • Meds
    • Steroid use
  • Other systemic diseases 
    • Galactosemia
    • Wilson disease
    • Hypocalcemia
    • Diabetes 

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23

What are the causes of adult cataracts?

  • Age-associated
  • Diabetic
  • Traumatic or post-ocular surgery
  • Steroid-induced 

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