Eye Pathology Flashcards
What are the layers of the Cornea?
–Epithelium–
Bowman’s Membrane
–Stroma–
Descemet’s Membrane / Endothelium
How are the fibers arranged in the lens and cornea to maximize transparency?
All the collagen fibers are arranged in parallel to obstruct the least amount of light, but when the fibers become disorganzied is when opacity takes over.
How does the cornea get nutrients to the cells?
By Diffusion – no vessels in the cornea
– cells expel nucleus
What happens if the Descemet membrane is disrupted?
The endothelial cells present pump out the water from the stroma to keep the fibers properly organized.
If a 4 year old is found to have corneal opacity and a cataracts, otherwise is normal, what might be his diagnosis?
– Peter’s Anomaly Type 2
What is the etiology of Peter’s Anomaly and what is the cause of the symptoms?
- Descemet’s Membrane did not develop properly congenitally – does not pump out the water from cornea disrupting the fibers in the cornea
- anterior eye agenesis – can disrupt lens too
If there is corneal opacity with apparent adhesions, what might be present?
– Peter’s Anomaly Type 1 –
If the stroma of the cornea is damaged, then what most likely will be the long term consequence?
– Scar - disorganization of fibers
If a 56 year old female presents to the office with diminished vision in one of her eyes over many years. On exam you visualize gutttae, might be the cause?
Fuch’s Cornea Dysplasia
- progressive dysfunction of the Descemet’s membrane allowing fluid to build up inside
- thickens stroma with fluid filled cysts
Why is the lens susceptible to TORCH infections?
– due to immune cells not regularly circulating through to eliminate the infections
If an adopted child is found to have a catarcts and his mother did not have any eye abnormalities, what might be the cause? The child does have apparent hearing loss as well.
– Toga Virus – Rubella
If a child has chronic asthma with frequent visits to the hospital to treat his asthma and presents to the office with vision disruption. What might be the cause?
- Chronic Steroid Use
- DM Type 1
Can affect older adults as well
What is the most common cause of catarcts in older adults?
- Uncontrolled DM
- - Elevated HgA1c
What is the purpose of the Retinal Pigmented Epithelial?
- nourishes the photoreceptors
- absorbs scattered light
- blood-retina barrier
- eliminates old photoreceptors
If a patient is diagnosed with Retinitis Pigmentation, what might be the clinical symptoms?
- Compromised night vision
- - Rhodopsin mutated, mostly only in RODS, no Cones
What is the genetic defect in Retinitis Pigmentation?
Rhodopsin – mutated and unable to activate coupled G-proteins when Retinal changes shape from responding to light.
How is Retinitis Pigmentation inherited and what is a unique characteristic?
- Central vision is not as affected as night or peripheral vision
- inherited in all ways
What is the difference between dry and wet macular degeneration?
Dry – drusen build up over time, which seems to affect some people and not others, which damage the pigmented epithelial leading to photocell loss
Wet – blood vessels from the retina invade the outer layers of the retina and macula obstruction vision
If a baby is born prior to 31 weeks what eye abnormality are they susceptible for?
Retinopathy of Prematurity
– Vasculature of the retina had not completely developed at the time of birth, but then stops at the time of birth. Then secretes lots of VEGF inducing vessel growth.
What patients are most susceptible for retinal detachments?
- Retinopathy of Prematurity
- - Untreated DM
What are the most common treatments for retinol prematurity and degeneration?
- Laser to destroy the tissue that is secreting the VEGF
- - Anti-VEGF to prevent the VEGF from acting
What kind of abnormalities are caused by chronic DM in the eyes?
- Microaneurysms
- Flame Hemorrhages
The small vessels become abnormal and disrupted, causing pruning – then areas become hypoperfused and secrete VEGF - Weakening of the vessels and surrounding tissues leading to retinal detachment
If upon retinal histology of a patient with abnormal vision, you find Flexner-Wintersteiner Bodies, what might be the cause?
Retinoblastoma
– loss of Rb tumor suppressor gene
Bilateral = inherited
Unilater = sporadic
Why does glaucoma cause progressive vision loss over time and how?
- Increased intraocular pressure
- - Puts pressure on the optic nerve slowly damaging the fibers due to the pressure losing the optic nerve
If a patient has a cardiac event and while he is recovering he complains of a partial loss in vision in one of his eyes, you exam him to find a “cherry red spot”, what might be the cause?
Central Retinal Artery Occulsion
- lack of blood flow to the retinal artery
- loss of inner retina layers
Commonly from embolism/artherosclerosis
