Complete the following: What is meant by 20/70 vision? What is meant by 20/10 vision? What visual problem is created by astigmatism? Why does the near point of accommodation often increase with age? Describe the eye defect that causes color-deficient vision. __

Question

Want to see more full solutions like this?

Answer 1

Textbook Question

Chapter 35, Problem 1.5A

Complete the following:

What is meant by 20/70 vision? ______________________
What is meant by 20/10 vision? ______________________
What visual problem is created by astigmatism? ______________________
Why does the near point of accommodation often increase with age? ______________________
Describe the eye defect that causes color-deficient vision. ______________________

a)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/70 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/70 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 70 feet apart.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 70 feet apart.

b)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/10 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/10 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 10 feet apart. This means the eyesight of the person fat better than that of the normal human being.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 10 feet apart.

c)

Expert Solution

Summary Introduction

To determine:

The problem caused by astigmatism.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

Any fault in the shape of cornea leads to astigmatism. A person suffering from astigmatism, has irregular shaped cornea. Due to this light refracts in an altered manner to the retina. This leads to fuzzy, blurry, and distorted vision.

Conclusion

Astigmatism leads to blurred and distorted vision.

d)

Expert Solution

Summary Introduction

To determine:

The near point accommodation often increases with age.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

With age, the lens of the eyes become hard that reduces the ability of eye to accommodate. As the lens hardens it becomes more spherical leading to increase in refractive power to focus on near objects. This condition is called presbyopia, that causes decrease in the near point of vision.

Conclusion

The near point accommodation often increases with age because with age the lens gets hardened.

e)

Expert Solution

Summary Introduction

To determine:

The eye defect that causes color-deficient vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The color-deficient vision means that the person is color blind, the condition termed as achromatopsia. Such people can see only grey, black or white colors. If color blindness is inherited then it affects only one eye and if it is caused by injury then it affects one eye only.

Conclusion

The eye defect that causes color-deficient vision is the color blindness.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!

Students have asked these similar questions

What is behavioral adapt

22. Which of the following mutant proteins is expected to have a dominant negative effect when over- expressed in normal cells? a. mutant PI3-kinase that lacks the SH2 domain but retains the kinase function b. mutant Grb2 protein that cannot bind to RTK c. mutant RTK that lacks the extracellular domain d. mutant PDK that has the PH domain but lost the kinase function e. all of the above

What is the label ?

Answer 2

Textbook Question

Chapter 35, Problem 1.5A

Complete the following:

What is meant by 20/70 vision? ______________________
What is meant by 20/10 vision? ______________________
What visual problem is created by astigmatism? ______________________
Why does the near point of accommodation often increase with age? ______________________
Describe the eye defect that causes color-deficient vision. ______________________

a)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/70 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/70 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 70 feet apart.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 70 feet apart.

b)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/10 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/10 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 10 feet apart. This means the eyesight of the person fat better than that of the normal human being.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 10 feet apart.

c)

Expert Solution

Summary Introduction

To determine:

The problem caused by astigmatism.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

Any fault in the shape of cornea leads to astigmatism. A person suffering from astigmatism, has irregular shaped cornea. Due to this light refracts in an altered manner to the retina. This leads to fuzzy, blurry, and distorted vision.

Conclusion

Astigmatism leads to blurred and distorted vision.

d)

Expert Solution

Summary Introduction

To determine:

The near point accommodation often increases with age.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

With age, the lens of the eyes become hard that reduces the ability of eye to accommodate. As the lens hardens it becomes more spherical leading to increase in refractive power to focus on near objects. This condition is called presbyopia, that causes decrease in the near point of vision.

Conclusion

The near point accommodation often increases with age because with age the lens gets hardened.

e)

Expert Solution

Summary Introduction

To determine:

The eye defect that causes color-deficient vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The color-deficient vision means that the person is color blind, the condition termed as achromatopsia. Such people can see only grey, black or white colors. If color blindness is inherited then it affects only one eye and if it is caused by injury then it affects one eye only.

Conclusion

The eye defect that causes color-deficient vision is the color blindness.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!

Answer 3

Textbook Question

Chapter 35, Problem 1.5A

Complete the following:

What is meant by 20/70 vision? ______________________
What is meant by 20/10 vision? ______________________
What visual problem is created by astigmatism? ______________________
Why does the near point of accommodation often increase with age? ______________________
Describe the eye defect that causes color-deficient vision. ______________________

a)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/70 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/70 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 70 feet apart.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 70 feet apart.

b)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/10 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/10 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 10 feet apart. This means the eyesight of the person fat better than that of the normal human being.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 10 feet apart.

c)

Expert Solution

Summary Introduction

To determine:

The problem caused by astigmatism.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

Any fault in the shape of cornea leads to astigmatism. A person suffering from astigmatism, has irregular shaped cornea. Due to this light refracts in an altered manner to the retina. This leads to fuzzy, blurry, and distorted vision.

Conclusion

Astigmatism leads to blurred and distorted vision.

d)

Expert Solution

Summary Introduction

To determine:

The near point accommodation often increases with age.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

With age, the lens of the eyes become hard that reduces the ability of eye to accommodate. As the lens hardens it becomes more spherical leading to increase in refractive power to focus on near objects. This condition is called presbyopia, that causes decrease in the near point of vision.

Conclusion

The near point accommodation often increases with age because with age the lens gets hardened.

e)

Expert Solution

Summary Introduction

To determine:

The eye defect that causes color-deficient vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The color-deficient vision means that the person is color blind, the condition termed as achromatopsia. Such people can see only grey, black or white colors. If color blindness is inherited then it affects only one eye and if it is caused by injury then it affects one eye only.

Conclusion

The eye defect that causes color-deficient vision is the color blindness.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!

Answer 4

Textbook Question

Chapter 35, Problem 1.5A

Complete the following:

What is meant by 20/70 vision? ______________________
What is meant by 20/10 vision? ______________________
What visual problem is created by astigmatism? ______________________
Why does the near point of accommodation often increase with age? ______________________
Describe the eye defect that causes color-deficient vision. ______________________

a)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/70 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/70 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 70 feet apart.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 70 feet apart.

b)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/10 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/10 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 10 feet apart. This means the eyesight of the person fat better than that of the normal human being.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 10 feet apart.

c)

Expert Solution

Summary Introduction

To determine:

The problem caused by astigmatism.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

Any fault in the shape of cornea leads to astigmatism. A person suffering from astigmatism, has irregular shaped cornea. Due to this light refracts in an altered manner to the retina. This leads to fuzzy, blurry, and distorted vision.

Conclusion

Astigmatism leads to blurred and distorted vision.

d)

Expert Solution

Summary Introduction

To determine:

The near point accommodation often increases with age.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

With age, the lens of the eyes become hard that reduces the ability of eye to accommodate. As the lens hardens it becomes more spherical leading to increase in refractive power to focus on near objects. This condition is called presbyopia, that causes decrease in the near point of vision.

Conclusion

The near point accommodation often increases with age because with age the lens gets hardened.

e)

Expert Solution

Summary Introduction

To determine:

The eye defect that causes color-deficient vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The color-deficient vision means that the person is color blind, the condition termed as achromatopsia. Such people can see only grey, black or white colors. If color blindness is inherited then it affects only one eye and if it is caused by injury then it affects one eye only.

Conclusion

The eye defect that causes color-deficient vision is the color blindness.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!

Answer 5

Textbook Question

Answer 6

Textbook Question

Answer 7

a)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/70 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/70 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 70 feet apart.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 70 feet apart.

b)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/10 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/10 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 10 feet apart. This means the eyesight of the person fat better than that of the normal human being.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 10 feet apart.

c)

Expert Solution

Summary Introduction

To determine:

The problem caused by astigmatism.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

Any fault in the shape of cornea leads to astigmatism. A person suffering from astigmatism, has irregular shaped cornea. Due to this light refracts in an altered manner to the retina. This leads to fuzzy, blurry, and distorted vision.

Conclusion

Astigmatism leads to blurred and distorted vision.

d)

Expert Solution

Summary Introduction

To determine:

The near point accommodation often increases with age.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

With age, the lens of the eyes become hard that reduces the ability of eye to accommodate. As the lens hardens it becomes more spherical leading to increase in refractive power to focus on near objects. This condition is called presbyopia, that causes decrease in the near point of vision.

Conclusion

The near point accommodation often increases with age because with age the lens gets hardened.

e)

Expert Solution

Summary Introduction

To determine:

The eye defect that causes color-deficient vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The color-deficient vision means that the person is color blind, the condition termed as achromatopsia. Such people can see only grey, black or white colors. If color blindness is inherited then it affects only one eye and if it is caused by injury then it affects one eye only.

Conclusion

The eye defect that causes color-deficient vision is the color blindness.

Answer 8

a)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/70 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/70 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 70 feet apart.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 70 feet apart.

Answer 9

a)

Expert Solution

Answer 10

a)

Expert Solution

Answer 11

Expert Solution

Answer 12

Summary Introduction

To determine:

The meaning of 20/70 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Answer 13

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/70 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 70 feet apart.

Answer 14

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 70 feet apart.

Answer 15

b)

Expert Solution

Summary Introduction

To determine:

The meaning of 20/10 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/10 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 10 feet apart. This means the eyesight of the person fat better than that of the normal human being.

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 10 feet apart.

Answer 16

b)

Expert Solution

Answer 17

b)

Expert Solution

Answer 18

Expert Solution

Answer 19

Summary Introduction

To determine:

The meaning of 20/10 vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Answer 20

Explanation of Solution

The visual acuity, sharpness of vision, is determined by the measuring the ratio of vision by standing 20 feet apart from the given object. 20/10 vision means that the person must be at 20 feet to see the object for which a normal vision person must be 10 feet apart. This means the eyesight of the person fat better than that of the normal human being.

Answer 21

Conclusion

20/70 vision means that a person should be 20 feet apart to see the object to which a normal vision person can see 10 feet apart.

Answer 22

c)

Expert Solution

Summary Introduction

To determine:

The problem caused by astigmatism.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

Any fault in the shape of cornea leads to astigmatism. A person suffering from astigmatism, has irregular shaped cornea. Due to this light refracts in an altered manner to the retina. This leads to fuzzy, blurry, and distorted vision.

Conclusion

Astigmatism leads to blurred and distorted vision.

Answer 23

c)

Expert Solution

Answer 24

c)

Expert Solution

Answer 25

Expert Solution

Answer 26

Summary Introduction

To determine:

The problem caused by astigmatism.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Answer 27

Explanation of Solution

Any fault in the shape of cornea leads to astigmatism. A person suffering from astigmatism, has irregular shaped cornea. Due to this light refracts in an altered manner to the retina. This leads to fuzzy, blurry, and distorted vision.

Answer 28

Conclusion

Astigmatism leads to blurred and distorted vision.

Answer 29

d)

Expert Solution

Summary Introduction

To determine:

The near point accommodation often increases with age.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

With age, the lens of the eyes become hard that reduces the ability of eye to accommodate. As the lens hardens it becomes more spherical leading to increase in refractive power to focus on near objects. This condition is called presbyopia, that causes decrease in the near point of vision.

Conclusion

The near point accommodation often increases with age because with age the lens gets hardened.

Answer 30

d)

Expert Solution

Answer 31

d)

Expert Solution

Answer 32

Expert Solution

Answer 33

Summary Introduction

To determine:

The near point accommodation often increases with age.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Answer 34

Explanation of Solution

With age, the lens of the eyes become hard that reduces the ability of eye to accommodate. As the lens hardens it becomes more spherical leading to increase in refractive power to focus on near objects. This condition is called presbyopia, that causes decrease in the near point of vision.

Answer 35

Conclusion

The near point accommodation often increases with age because with age the lens gets hardened.

Answer 36

e)

Expert Solution

Summary Introduction

To determine:

The eye defect that causes color-deficient vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Explanation of Solution

The color-deficient vision means that the person is color blind, the condition termed as achromatopsia. Such people can see only grey, black or white colors. If color blindness is inherited then it affects only one eye and if it is caused by injury then it affects one eye only.

Conclusion

The eye defect that causes color-deficient vision is the color blindness.

Answer 37

e)

Expert Solution

Answer 38

e)

Expert Solution

Answer 39

Expert Solution

Answer 40

Summary Introduction

To determine:

The eye defect that causes color-deficient vision.

Introduction:

The eyes are the main organ of the visual system. They are responsible for providing the animals with vision as they have receptors to receive and sense visual information. Eyes collect light in the form of wavelength and then convert it into electro-chemical impulses.

Answer 41

Explanation of Solution

The color-deficient vision means that the person is color blind, the condition termed as achromatopsia. Such people can see only grey, black or white colors. If color blindness is inherited then it affects only one eye and if it is caused by injury then it affects one eye only.