Anatomy Flashcards
(16 cards)
What are the three main refractive media of the eye?
Cornea, lens, vitreous
These structures are critical for focusing light onto the retina.
What is the primary role of the cornea?
Refraction of light
The cornea accounts for approximately two-thirds of the eye’s total refractive power.
What are the five layers of the cornea?
- Epithelium
- Bowman’s membrane
- Stroma
- Descemet’s membrane
- Endothelium
Each layer has distinct structural and functional characteristics.
What is the significance of the corneal endothelium?
It actively keeps the stroma dehydrated
Damage to the corneal endothelium can lead to corneal edema.
Define refraction.
The change in direction of light as it passes from one medium to another, of different optical density
This process is essential for focusing light on the retina.
What factors contribute to corneal transparency?
- Avascular
- Smooth epithelium
- Regular stromal arrangement
- Relatively ‘dry’ structure
These factors help maintain the clarity of the cornea.
What factors can reduce corneal transparency?
- Significantly increased IOP
- Oedema due to any cause
- Fibrosis after trauma
- Inflammation and infection
These conditions can lead to visual impairment.
What is the anatomy of the lens?
Transparent, bi-convex structure
It accounts for one-third of the total refractive power of the eye.
How does the lens accommodate?
By changing its shape
This adjustment allows the eye to focus on objects at different distances.
What changes occur in the lens with age?
- No cells are lost
- Lens fibers migrate to the center
- Capsule thickens
- Central portion becomes sclerosed and yellowish
These changes can lead to a reduction in visual acuity.
What is the role of the vitreous body?
Provides structural support and maintains the shape of the eyeball
It is located between the lens and retina.
What is the difference between posterior vitreous detachment and retinal detachment?
Posterior vitreous detachment is the separation of the vitreous from the retina, while retinal detachment involves the retina itself separating from the underlying tissue
Both conditions can lead to vision loss if not treated.
What are the risk factors for retinal detachment?
- Age
- Previous eye surgery
- Trauma
- High myopia
Understanding these factors is crucial for prevention and early detection.
True or False: The cornea is avascular.
True
It relies on diffusion from the tear film for oxygen.
Fill in the blank: The cornea accounts for _____ of the total refractive power of the eye.
2/3
This is due to the significant refractive index difference at the air/tear film interface.
What is the nerve supply to the cornea?
Via the long ciliary nerve
This nerve pathway is crucial for corneal sensation.
