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Unit 1 syence > Structure of the Eyes > Flashcards

Structure of the Eyes Flashcards

1
Q

How does light move into our eyes?

A

Light is reflected by objects we look at and it travels as rays into our eyes.

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2
Q

What happens when we look at distant objects?

A

When we view distant objects the light enters our eyes in almost parallel lines and so they need a little refraction or bending to focus them as an image on the retina (light-sensitive surface at the back of the eye).

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3
Q

What happens when we view close objects?

A

Light from close objects spreads as it enters the eye so needs to be refracted more, so the lens relaxes into spherical form

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4
Q

How is light converted into an image?

A

The eye focuses rays of light onto the retina which sends nerve messages along the optic nerve to the brain where images are interpreted.

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5
Q

What is the eye?

A

The eye is a tough capsule filled with both watery and jelly like fluids called the humours, that keep the eye in shape and help nourish it.

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6
Q

What is the outside of eye protected by?

A

by a tough layer called the sclerotic coat (sclera). The sclerotic coat is the white bit we see in our eye.

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7
Q

How does the eye work?

A

Light entering the eye is refracted by the conjunctiva and cornea and then further refracted by the lens.
When viewing far objects – the lens is stretched into a thinner shape that will refract less.
When reading or viewing close objects – the lens relaxes into is spherical form.
When we age we lose elasticity in our lens which gives us sight issues. This is why we often require reading glasses when we are older.

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8
Q

Define refract?

A

when a ray of light changes direction when it enters at an angle

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9
Q

What are Rods and Cones?

A

Light sensitive cells in the retina

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10
Q

What do rods and cones do?

A

These are connected to nerve cells which exit the eye by the optic nerve. The optic nerve leaves the eye where there are no rods and cones and we cannot detect light if it falls on this region – the blind spot

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11
Q

Why do we use rods in darker conditions?

A

Rods are more sensitive to light and so we use them in darker conditions and to give us early warning (eg: when we see something in the corner of our eye)

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12
Q

Where are rods located?

A

They are distributed around the sides of the retina and share nerve cells

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13
Q

Why would we use cones in bright light?

A

Cones work in bright light, allowing us to view colours. They connect to individual nerve cells to provide us with precise vision.

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14
Q

Where are cones located?

A

They are concentrated at the back of the eye in the macula and in the centre of the retina – the fovea – where there are only cones. This is what we use when we look closely at something.

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15
Q

Whats the pupil do?

A

Allows light into the eye

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16
Q

What is the iris and what does it do?

A

Pigmented ring of muscle that contracts and relaxes to allow more or less light into the eye

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17
Q

Whats the lens do?

A

Refract and focus light onto the retina

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18
Q

What do tear glands do?

A

Secretes tears to lubricate and clean the eye

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19
Q

What does humours or fluids do?

A

To hold and support the eye and allow light through

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20
Q

Whats conjunctiva do?

A

Outer protective layer of the eye. Tears lubricate this.

21
Q

Whats the cornea do?

A

It’s the transparent front of eye to allow light in through the pupil

22
Q

Whats the retina do?

A

Contains cone and rod light receptor cells to detect changes in light

23
Q

Whats the macula?

A

Highly concentrated area of the retina with receptor cells

24
Q

Whats the optic nerve do?

A

Carries impulses from the eye to the brain

25
Q

How is the retina connected to the brain?

A

Connected to brain via the optic nerve (Blind Spot)

26
Q

What are the different malfunctions of the eye?

A
  1. Glaucoma
  2. AMD – Age-related macular degeneration
  3. Cataracts
  4. Retinopathy
27
Q

Whats glaucoma?

A

Glaucoma is an eye condition where the optic nerve becomes damaged.

28
Q

What are some glaucoma symptoms?

A

It can lead to loss of vision if not detected and treated early on.

29
Q

What is glaucoma caused by?

A

It usually occurs when the aqueous fluid in the eye cannot drain properly, which increases the pressure inside the eye and puts pressure on the nerve fibres of the retina.

30
Q

What does AMD stand for?

A

Age-related macular degeneration (AMD)

31
Q

What is AMD ?

A

Age-related macular degeneration (AMD) is a painless eye condition that causes you to lose central vision, usually in both eyes.

32
Q

What are some AMD symptoms?

A

Vision becomes increasingly blurred, so reading becomes difficult, colours appear dull and faces are hard to recognise. AMD does not affect peripheral vision.

33
Q

What are the two types of AMD?

A

Dry AMD

Wet AMD

34
Q

What is Dry AMD?

A

Dry AMD is a condition that develops when the cells of the macula become damaged by a build-up of deposits called drusen. It is the most common and least serious type. Vision loss takes many years to develop. However, some people with dry AMD develop wet AMD.

35
Q

What is Wet AMD?

A

develops when abnormal blood vessels form underneath the macula and damageits cells. Without treatment vision can deteriorate in days.

36
Q

What are cataracts?

A

Cloudy patches that develop in the lens of the eye and can cause blurred or misty vision as they stop some of the light from reaching the retina.

37
Q

Symptoms of cataracts?

A

Over time the cataracts start affecting vision.

THEY cause blurred or misty vision as they stop some of the light from reaching the retina.

38
Q

What are some treatments for cataracts?

A

Many people with cataracts will eventually need surgery to remove/replace the effected lens.

39
Q

Why might someone develop cataracts?

A

There are many reasons for people developing cataracts, however most are due to individuals lifestyle choices e.g. smoking.
Changes in the lens appear to be more common as people age.

40
Q

Whats Diabetic Retinopathy?

A

Diabetic retinopathy is a common complication of diabetes. It occurs when high blood sugar levels damage the cells of the retina.

41
Q

How is diabetic retinopathy caused?

A

To work effectively the retina needs a constant supply of blood, which it receives through a network of tiny blood vessels.

Over time, a persistentlyhigh blood sugar level can damage these blood vessels by causing them to narrow and leak – this damages the retina and stops it from working.

42
Q

diabetic retinopathy symptoms?

A

If untreated, it can cause blindness.

43
Q

How can diabetic retinopathy be avoided?

A

It can be easily avoided by regular monitoring and a balanced active lifestyle.

44
Q

Why is Diabetic Retinopathy becoming more common?

A

Diabetic Retinopathy is becoming more common with a rise in cases of Type II diabetes

45
Q

Whats a treatment for glaucoma ?

A

using eye drops for many years or for life. Using your drops regularly helps to keep your eye pressure under control and prevents damage to your sight.

46
Q

Treatment for Wet AMD?

A

NHS will offer a group of medications called anti-vascular endothelial growth factor (anti-VEGF)drugs. They are injected into the eye.

47
Q

Whats a treatment for Dry amd?

A

There is no way to treat Dry AMD

48
Q

What is the treatment for Cataracts ?

A

Cataracts can be removed by surgery. Cataract surgery removes your cloudy lens and replaces it with an artificial lens.

49
Q

What are the treatments for Diabetic Retinopathy?

A

Keeping your blood glucose or blood sugar level within normal levels.
Tightly controlling your blood pressure.
Controlling your cholesterol levels.
Keeping fit and maintaining a healthy weight.

Unit 1 syence (23 decks)

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