Introduction to Ophthalmic Pathology Flashcards
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
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
The ______ is the transparent covering, or “window”, of the eye.
Cornea
What are the 5 layers of the cornea?
- Epithelium (regenerates)
- Bowman’s membrane
- Stroma (acellular)
- Descemet’s membrane
- Endothelium
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
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
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%)
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
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
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
What is the corneal response to injury? (3)
- Epithelial injury & death
- Disruption of Bowman’s layer & stromal lamellae
- Keratocyte injury & death
What are the steps of corneal repair? (8)
- 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
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
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
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
What structure is being described?
Transparent biconvex structure
Located behind the pupil
Attached in place by the zonules
Lens
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
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
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
What is this?
Rubella Retinopathy
- “Salt & pepper” appearance
- Damage of the retina pigmented epithelial layer
- Vision in most instances is preserved
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
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
What are the causes of adult cataracts?
- Age-associated
- Diabetic
- Traumatic or post-ocular surgery
- Steroid-induced
