LEC 12

What is the function of the Lacrimal gland?

produce tears

• to MOISTEN and LUBRICATE eye surface

• tears contain ENZYMES that KILL BACTERIA

• DRAIN into:

  • lacrimal duct —> nasal cavity

The oil component found in tears is produced by which glands?

Tarsal glands

What are Tarsal glands?

sebaceous glands on inside of the eyelid

• produce sebum —> lubricates the eyeball.

Ordinarily, it is not possible to transplant tissues from one person to another without rejection, yet corneas can be transplanted. Why?

cornea = avascular

• no blood supply except around periphery

  • no tissue rejection

What is another term for the zonule?

suspensory ligament of lens.

Describe Presbyopia.

old eyes

• around age 45–50

• lens no longer accommodates

• lens loses flexibility —less able to round up

• stays in the position for seeing far away —> difficult to focus on nearby objects

What are cataracts?

clouding of the lens

What is the function of the iris?

constrict or dilate the pupil

regulate amount of light passing to visual receptors

What is the name of the region of the retina which has the highest amount of cones?

Fovea centralis

very center of the macula

Visual information travels from the retina deep into the brain via which pathway? Is it visible with an ophthalmoscope in this region?

optic chiasma

• on the surface of the brain

• not visible with an ophthalmoscope.

After traveling through the optic chiasma, which section of the brain receives the visual information?

occipital lobe —> visual information processed here

Which 6 structures are visible when an ophthalmoscope is used to look inside the eye?

1. Fovea centralis

2. Lens

3. Optic disc

4. Macula

5. Blood vessels

6. Retina

FLOMBR

What causes retinal detachment?

Does it cause blindness immediately?

a blow to the eye

no immediate blindness = detached portion still has capillaries supplying oxygen for a few hours

Why is retinal detachment considered a medical emergency?

not immediately LASERED back into place = permanent blindness

Describe Hyperopia.

farsightedness

• occurs when the eyes are too short

• CAN see FAR, not NEAR

What causes Myopia?

nearsightedness

caused by eyes that are too long

person can see NEAR, NOT FAR

How do hyperopia and presbyopia differ?

hyperopia = lens CAN still accommodate

presbyopia = lens CANNOT accommodate anymore

What is astigmatism?

irregularly shaped cornea

What is glaucoma?

Increased pressure in anterior chamber of eye

• can lead to blindness

What are the 4 main conditions that cause blindness?

cataracts

glaucoma

diabetic retinopathy

macular degeneration

What is the 20-20-20 rule?

Every 20 MINUTES

look at something 20 FEET away

20 SECONDS

help protect your eyesight