LASIK - New Senior Secondary Curriculum Goals: NOS...

Senior Form Physics – LASIK

LASIK (角膜激光矯視)Teacher’s Version (with video exemplars)

NOS/STSE Features1. Technology can come before the

understanding of the related science.

2. Technology is driven by societal demand and human’s need.

3. Development in science can advance technology. Likewise progress in technology can advance science.

4. Science and technology are affected by social factors.

You can click an icon like this to access the activities in this package.

You can click an icon like this to access the PowerPoint files in this package.

You can click an icon like this to access the exemplar videos in this package.Icons of different colours indicate exemplars from different teachers.

Table of Contents

Introduction (i)

Activity 1: - Warm-up Revision

1 P.1

Activity 2: - Investigation: Let’s do “eye surgery” in the Laboratory P.3Activity 3: - Learning more about the nature of science through the history of the development of refractive surgery

P.7

Activity 4: - Making informed decisions: Is LASIK for everyone? - Comparing LASIK with two traditional ways to correct

refractive errorsP.9

Activity 5: - Truth and Honesty P.13

Appendix 1: References P.15

Appendix 2: Investigation Guide P.16

Appendix 3: Lesson Plan P.22

© 2007 The University of Hong Kong – Faculty of Education. All rights reserved.

If the links do not work, try again by pressing the “Ctrl” key and clicking the icon at the same time.


Introduction

Rationale

LASIK, which stands for ‘Laser in situ keratomileusis’, is an example of modern technology

where a laser beam is used to correct vision by reshaping the cornea of the eye. As short-

sightedness is very common among Chinese populations and the demand for LASIK surgery

is increasing, this is a highly relevant topic in combining science, technology and their effects

on society (STS) for students. The core part of this teaching package is the simulation

investigation of LASIK. The aim of the investigation is to move away from traditional

‘cookery book’ investigations and emphasize interconnections between science, technology

and society.

The teaching package includes an article to better understand the nature of science through

the developmental history of refractive surgery, an activity that highlights the risks of LASIK

and guides the students to make informed decisions. The teaching package concludes by

guiding the students to think critically about the contents of advertisements for technology

based products which have been developed by applying scientific principles, so that their

learning of science becomes useful in the material world, perhaps saving money and making

better judgments.

Level of study Number of lessons

Form 3 – Form 7 4 lessons (each lesson 35-40 minutes)

Contents

1. Revision of the structure of eyes and their refractive errors: short-sightedness, long-

sightedness and astigmatism

2. Simulation of the LASIK operation by investigation

3. Developmental history of refractive surgery

4. Requirements for a good candidate for LASIK

5. Risks associated with LASIK

6. Cost & Benefit Analysis: Comparison of LASIK with spectacles and contact lenses

7. Judging advertisements for LASIK (Truth and Honesty)

Teaching package includes:

1. Worksheets (Teacher’s Version and Student’s Version)

2. A Teaching PowerPoint

(i) © 2007 The University of Hong Kong – Faculty of Education. All rights reserved.


Activity 1

Warm-up Revision

1. The following paragraph summarizes how the different parts of our eyes cooperate to allow us to see objects. Fill in the blanks to complete the paragraph.

Structure of the eyes

T The eyes are optical organs that allow us to see. The cornea is the front, transparent part of the eye. It allows light to enter and begins to focus it. After passing through the cornea, light enters a transparent fluid called the aqueous humour and then hits the iris. An opening in the middle of the iris, called the pupil, controls the amount of light entering each eye. The light then goes through a clear lens, which focuses the light onto the back of the eye. The light rays travel through another transparent fluid called the vitreous humour and finally reach retina. The light energy is then changed into nerve impulses which travel to the brain through the optic nerve.

2. Label this eye diagram with the words you filled in from the paragraph above.

P. 1 © 2007 The University of Hong Kong – Faculty of Education. All rights reserved.

Optic nerveCornea

Optic nerve

Vitreous Humour

Iris

Pupil

Lens

Retina

Cornea

AqueousHumour


Do you know?You may have learnt that the lens is the main part of the eye which refracts the light. Which other parts also play a role in refracting light rays? You will get the answer shortly.



Refractive Errors (折射誤差)

If an image is not formed sharply on the retina, it is usually because of refractive errors and the result is blurred vision. Refractive errors include astigmatism (散光), short-sightedness (近視), and long-sightedness (遠視). Because objects form images on the retina of the eye by refraction, we use the general term “refractive errors” to describe them.

People who are short-sighted are able to see things near to them quite clearly, but cannot see things very well that are far way. Long-sighted people are able to see things far away clearly, but have difficulty seeing things that are close. Astigmatism causes images to appear distorted (see below).

3. With the help of ray diagrams, illustrate how a normal eye and a short-sighted eye form an image. How can we use a concave lens to correct short-sightedness?

(Optional Question)4. What are the causes of astigmatism? Explain it with diagram(s) if necessary.

The following are two main causes of astigmatism:1. The curvature of the cornea is different in different cross-sections of the eye ball.(Figure a). 2.The axis of the lens does not pass through the yellow spot, i.e. the lens isslightly tilted (Figure b)



Activity 2

Let’s do “eye surgery” in the laboratory! LASIK operation – a form of eye surgery in which the cornea of a patient is reshaped so that the image formed is adjusted back onto the retina. Now you are going to simulate this eye surgery

List of equipment and materials you will find useful for your ‘surgery’

Lamp housing with a letter F as an illuminated objectConvex lens covered with a black plastic sheet with a center opening (pupil)to simulate our eye lens“Cornea” made from gelatin Clamps and a standto fix the position of the lamp housing and the ‘eye’Lens holderto fix the position of the ‘lens’ and ‘cornea’Movable stand with a piece of paper attached to its top surface to act as a screento simulate the retinaLighter or Hot waterto heat up the tools(e.g. spatula) used for reshaping the cornea

Caution! Don’t over heat the spatula or the metal ring. Hot gelatine liquid may “spit” from the heated surface and hurt you!Any tools that can reshape the “cornea” e.g. Spatula, deflagrating spoon, scalpel, stirrer with ring handle, a ring made from metal wire…etc Remarks: Any tools that can flatten the cornea and make a donut shape on the surface of “cornea” are good tools for correction of short-sightedness and long-sightedness respectively.

You could ask for other tools you think are necessary for your “surgery”!

Investigation Setup

- The cornea is placed over the eye lens.

- A lamp house with an illuminated letter “F” acts as the object in front of the eye.

- A movable stand with a screen on it is used to capture the image.



Simulation of correcting short-sightedness1. In the case of short-sightedness, we simulate it by forming the image of an

object in front of the retina. For correction of short-sightedness, you have to reshape the cornea and move the image backward onto the retina (downward in the simulation set-up).

Procedure:Locate the image (illuminated letter “F”) on the movable stand sharply, this isthe image formed by the short-sighted eye.

(a) Think about how to reshape the cornea to correct the short sightedness -

Describe with the aid of a simple diagram how you can do so. Now try out your idea.

- Use the lighter / hot water to heat up the spatula/any other suitable tools

- As shown in the picture, use the heated spatula to flatten the cornea to refocus the image back to the retina surface.

(The cornea becomes more concave.)Remarks for 1(a) & 1(b): Teachers should not tell the answers to students directly. Guiding questions like “What kind of tool do you need to reshape the cornea?”, “Will you need to increase or decrease the converging power of the lens?”, “What shape will you make for the correction?” can be asked.

(b) Are your ideas successful? Please illustrate how, with the aid of a diagram. After the flattening of the cornea, it is found that the new position of the image is below the original one. As the lens is made more concave, the image is shifted backward to the retina.(As shown by the red arrow)



Simulation of correcting long-sightedness

2. In the case of long-sightedness, we simulate it by forming the image of an object behind the retina. For correction of long-sightedness, you have to reshape the cornea and move the image forward onto the retina (upward in the simulation set-up).

Procedure:Locate the image (illuminated letter “F”) on the movable stand sharply, it isthe image formed by the long-sighted eye.

(a) Think about how to reshape the cornea to correct the long sight - Describe with

the aid of a simple diagram how you think you can do so. Now try out your idea.

- Reshape the cornea with heated metal ring.

- The donut shape on the topmost of the cornea effectively increases the curvature of the cornea and increases the converging power of the eye

(Please see the remark in 1(a))

(b) Are your ideas successful? Please illustrate how, with the aid of a diagram. After the reshaping of the cornea, it is found that the new position of the image is above the original one. It is shown that the lens becomes more convex and the image is shifted towards to the retina. (As shown by the red arrow)



3. Doctors suggest that the thickness of the patient’s cornea is an important factor for whether a patient is suitable for LASIK surgery. Can you suggest a reason?

The correction requires removal of corneal tissues. For serious short-sightedness or long-sightedness, many tissues have to be removed. Possible rupture of the cornea may result if it is too thin.

After the investigation, you should have learnt that the lens is not the only part of the eye which refracts light.

Common MisconceptionMany students have a wrong concept that only the lens in the eye refracts light. Apart from the lens, the cornea, aqueous humour and vitreous humour also play a role in refracting the light.

Video Time

How is LASIK performed in the real world? Your teacher will show you a video demonstration of LASIK now.

Information Search

After the LASIK simulation investigation and the video demonstration of the surgery, you should have quite a good understanding of LASIK, but is it for everyone? Is there



any risk associated with LASIK? Let’s search for some articles or news on the web about the following two questions:

1. Is LASIK for everyone?2. What are the risks of LASIK?

You will be asked to share your findings with your classmates in activity 4.Notes: Teacher can ask students to look up information at home for group sharing and presentation during activity 4.

Activity 3 Learning more about the nature of science through the

history of development of refractive surgery

Notes: Teacher can show PowerPoint slides P.16-18 for warm up exercise, P.19 after Q.1 and P.20 after the whole activity as a summary.Warm up exercise: You will learn about the relationship between science, technology and society in this activity. Discuss the following questions with your classmates.1. What is Science? 2. What is Technology? 3. Which one (Science or Technology) comes first?

The long pursuit of correction of eye defectsThe quest for the correction of eye defects could date back to early Chinese civilization. Folklore states that people with short-sightedness put sandbags on their eyes at night. The pressure effect of the sandbags on the cornea changed the curvature, which focused the eyes for a short period the next morning.

Q1. Suggest possible reason(s) why the sandbags help to correct short-sightedness.

The pressure effect of the sandbags may cause two changes to the eyes: 1) Shorten the eye ball 2) Cornea may become less convex(Do you think those ancient people understood the scientific principle behind their practice?)

Q2. Before the invention of LASIK, we already had contact lenses and spectacle lenses. What encouraged scientists and technologists to invent LASIK?

Our need for good vision, society’s demands and health issues all encourage scientists to use theory to invent better ways to correct vision, since the existing technology (spectacles and contact lenses) could not satisfy our needs. E.g. It wastes time to clean up contact lenses. The pressure that the spectacles exert on


Technology can come before the understanding of the related science. (Q.1)

Technology is driven by societal demand and human’s need. (Q.2 & Q.3)


nose makes people feel not comfortable. Notes: Teacher can bring out the point that human’s pursuit of better life and being unsatisfied with the existing situation are always one of the drives for new invention and applications of scientific knowledge.

Fireman: The intense heat can deform the contact lenses. Professional drivers: Crushing may damage the spectacle lenses. (Any other reasonable answers are accepted) Remarks: In fact this is another example of societal demand which drives the development of technology.

1Q3. Can you list some occupations in which the use of spectacles/contact lenses is potentially dangerous? Explain the potential danger involved.

How were the ideas of refractive surgery developed 55 years ago?

In 1960, a Russian scientist, Dr. Fyodorov, gave birth to the idea of refractive surgery. One day he was treating a young boy who had fallen, and his glasses had broken and cut into his cornea. The damage simply shaved a layer off of the outer surface of the eye. The boy, previously having serious short-sight, now had improved vision in that eye! Dr. Fyodorov was surprised and studied the matter. He published his discoveries, but it was not until later that American doctors, who read about it, had enough funding to begin serious research.

How did the application of refractive surgery start in the U.S.?

Dr. Leo Bores brought the procedure to the United States. Americans also thought of using a laser. In 1978 an ophthalmologist (眼科醫師) successfully incorporated a high

intensity laser which allowed extremely high precision in cutting the cornea during refractive surgery. Since then “laser assisted refractive surgery” has become popular and over 10 million people have benefited from the surgery.

Q4. What critical technology enabled extreme high precision in refractive surgery? Comment on the influence of technology on science?

The Laser is the critical technology that enabled extremely accurate cutting of the cornea in refractive surgery.Notes: Teachers help the students to build up the concept that sometimes science leads technology, but also technology may lead science. E.g. the invention of the electron microscope enabled biologists to study biological tissues deeply which led to the advancement of biology and medical science.

Q5. A Russian scientist first discovered the potential of curing eye defects by refractive surgery, but American scientists made it popular.


Development in science can advance technology. Likewise progress in technology can advance science. (Q. 4)

Science and Technology are affected by social factors. (Q.5)


Why? What other factors were also critical for this scientific development?

The American scientists, not the Russians, had enough funds to do serious research on refractive surgery.(Teachers help the students to build up the concept that government policy and availability of research funds are also critical for development of scientific knowledge. Brilliant or inventive ideas often require manpower and resources to support the subsequent scientific research investigation)

Glossary:Ophthalmologist A medical doctor specializing in the diagnosis and medical treatment of visual

disorders and eye disease.

Activity 4

Making informed decisions: Is LASIK for everyone?Comparing LASIK with two traditional ways to correct refractive errors

Are you a “good candidate” for LASIK surgery? LASIK is not for everyone! Below is a list of requirements for a good LASIK candidate. Some of the statements are true and some are false. Share the information you searched in activity 2 with your classmates for the right answers.

A. A person who feels that wearing spectacles or contact lenses is quite convenient. (Remarks: If someone is quite satisfied with spectacles or contact lenses already, he does not have a strong reason to take risk.)

B. Above 18 years old since young eyes are still developing and may change more, thus wasting the surgery.

C. Less than 40 years old since this is the upper age limit for LASIK. (Remarks: There is no upper age limit for LASIK.)

D. Free of diseases of the cornea which can delay the wound healing process.

E. Able to bear some pain since the LASIK operation causes the eyes to be painful for a while. (Remarks: The LASIK operation will not cause the eyes to be painful.)

F. Not pregnant since hormone changes in pregnancy can cause changes in vision. G. Understand fully the benefits and possible side effects of the LASIK surgery

since knowing them is important for making informed decision.H. Only have a low level of shortsighted or longsighted-ness since the degree of

refractive error that LASIK can correct is limited. (Remarks: There is no limit for the degree of short-sightedness or long-sightedness for LASIK provided the cornea is thick enough for the operation.)

Notes: Teachers should discuss the options with the students before checking the answers with them.



The right requirements for LASIK candidates are:

B, D, F, G

Do you understand the Risks and Possible Side Effects of LASIK?

Typical side effects associated with refractive procedures:

Visual aberrations (色差) – Seeing hazy circles (光環) around lights at night

Dry eye - This usually goes away in the weeks to months following surgery

Irritation - Some patients experience some eye irritation and discomfort after surgery.

Sensitivity to light - Being more sensitive to light for a few days after surgery.

Under/over-correction - Additional surgery can be performed for a better result.

Discussion Time

Situation: You now understand the benefits, procedures and risks of LASIK, some of your friends come to seek an opinion from you on whether they should choose spectacles, contact lenses or LASIK to correct their refractive errors. You have to apply the knowledge you have about LASIK to help them analyze what to do. Divide yourselves into five groups for this activity.

Let’s consider the use of spectacles and contact lenses before discussing LASIK.

Spectacles

Wearing spectacles is a safe and popular method of correcting vision, but there can be limitations, such as when playing sports, work-related hazards or the eyeglass wearer may feel self-conscious.

Contact lenses



One advantage that contact lenses have over eye glasses is a wider field of vision. However, the wearers have to clean the lenses regularly, usually every night, to avoid the risk of infection; otherwise they have to bear the expense of daily or regular replacement. For some people with high astigmatism, contact lenses simply do not work.



Your friends’ backgrounds

Mary 16 years old, a secondary school student - 200o short-sighted in both eyes- Lazy and has irregular habits Attitude towards LASIK “LASIK? What is it?”

John 21 year old, an university student- 400o short-sighted in both eyes- Very conscious about his appearance and imageAttitude towards LASIK “LASIK is cool and fashionable!”

Peter 23 year old, a tennis coach- 400o short-sighted in both eyes- Plans to change occupation to fireman Attitude towards LASIK “Well…I think I have understood the procedures and the risks associated with LASIK already.”

Fiona 23 year old, an university student- Seriously short-sighted- Has eye allergy problems Attitude towards LASIK “I really want to try LASIK, can I?”

Vicky 28 year old, a teacher- Has thin cornea and dry eyes, - Desires to look more matureAttitude towards LASIK “I don’t think I’m a risk taker.”

How do you help them?

First we list the benefits, costs, risks and drawbacks of the three ways to correct refractive errors in the table below. Then we can analyze our friends’ situations and tell them or advice.

Benefits/ Effectiveness Cost Risks / Drawbacks

Spectacles

Contact Lenses

LASIK

Presentation time



After discussion, be prepared to present your group’s suggestions in front of class. If your group tends not to agree with the suggestions of other groups, challenge them, with reasons!

Expressing your view

At this stage you should have many ideas about LASIK in your mind. It is important for you to have your own thoughts rather than being a ‘bookworm’ memorizing all the information. Answer the following questions giving good reasons for your answers.

Q1. Do you think you will have LASIK surgery in the future? Why?

Guide the students to express their opinions with sound arguments.

Q2. The technology of refractive surgery is advancing at amazing speed. Do you think there will be such a day in which you cannot see any spectacle and contact lens on the street? Support your opinion with arguments.

Students are encouraged to express their opinions freely on this question. Answers must be supported by arguments.



Activity 5

Truth and Honesty

Below is an article modified from the promotional material of an eye centre that provides LASIK service. Read it carefully and then answer the questions on the next page.

Do I need LASIK?If you have ever experienced any of the following, LASIK is for you!- Wearing spectacles or contact lenses

is very inconvenient - Wearing contact lenses results in

discomfort, inflammation of the eyes or other serious problems

- In case of emergency, I will react slowly if I can’t put on spectacles or contact lenses immediately

- Perfect eye sight broadens career horizon

- Perfect eye sight makes me more attractive

- Perfect eye sight aids in sport

What is LASIK?LASIK is an advanced technology that corrects refractive errors, such as short- and long-sightedness and astigmatism by using computer-controlled laser to reshape the cornerRefractive errors are common in Hong Kong7 to 8 out of 10 Hong Kong people have to wear spectacles or contact lenses to correct refractive errors. Similar to other developed countries, increasingly more people need to wear spectacles. As of today, more than 1 million people worldwide have received LASIK with satisfactory result.

優惠期內，每隻 Turn a new page

LASIK is painless

LASIK corrects short- and long-sightedness and astigmatism. During an operation, aesthetic is first applied to rest the eye ball temporarily. The cornea is then cut into two layers. The lower layer is reshaped as needed by laser followed by replacement of the upper layer. No stitching is needed as the cornea will heal by itself.

We use state-of-the-art diagnostic equipment

We adopt Orbscan (角膜素描儀) and Zywave

(角膜分析儀) invented by Bausch and Lomb to examine the cornea accurately and give detailed analysis for the operation. With the use of the latest pupil identification technology, perfect result is achieved in each operation.

Why more consideration?

If you intend to: gain confidence, improve your career prospect, be attractive, be sportive, forget about wiping spectacles when you go to air-conditioned areas, LASIK is your one and only choice.



眼只需$6000 of your life!

Don’t want spectacles any more? Call our consultants at 987654321 now!

Only the benefits and the technology of LASIK are highlighted.

Some benefits are exaggerated. (e.g. the points in the last paragraph.)

Q1. What aspects of LASIK are highlighted in the article?

Q2. Do you think the article provides balanced information for potential consumers to make a wise decision about whether they should choose the LASIK operation? Explain?

No. The side effects and risks of LASIK are not mentioned at all in the article. Moreover, there are many points to create the fear that wearing spectacles or contact lenses will have a poorer quality of life, as shown in paragraph 1.

Q3. You can find many misleading advertisements in magazines and newspapers everyday, the results can be quite worrying if products and procedures such as LASIK are not promoted in a fair way. How could we deal with this issue?

Examples of measure we can take are: School Education plays an important role here because students build up the foundation of their values, knowledge and critical thinking in schools. If students are properly educated at school, they will be able to judge the contents of dishonest advertisements. Independent consumer associations can be set up to provide consumers with balanced information on



the pros and cons of the products via regular publications. Government should oversee popular health services that have potential danger such as refractive surgery, facial and fat-removal operations.

Remember that we should be always critical about the contents of the advertisements we see everyday!



Appendix 1: References

Hong Kong Sanatorium & Hospitalhttp://www.hksh.org.hk

Government Statistics on population with short-sightednesshttp://www.info.gov.hk/gia/general/200011/22/1122178.htm

U.S. Food and Drug Administrationhttp://www.fda.gov/cdrh/LASIK

International Society of Refractive Surgery of the American Academy of Ophthalmologyhttp://www.isrs.org

Medline Plus of the U.S. National Library of Medicinehttp://www.nlm.nih.gov/medlineplus/tutorials/lasik/htm/index.htm

Wikipedia - The free encyclopediahttp://en.wikipedia.org/wiki/Lasik

History of LASIK: Lasik-Eye-Surgery.infohttp://www.lasik-eye-surgery.info/history.html

History of LASIK: Westchester Vision Carehttp://www.westchestervision.com/historyoflasik.html

History of LASIK: Lasersight Technology Limitedhttp://www.slazus.co.za/lasik.htm


http://www.slazus.co.za/lasik.htm

http://www.westchestervision.com/historyoflasik.html

http://www.lasik-eye-surgery.info/history.html

http://en.wikipedia.org/wiki/Lasik

http://www.nlm.nih.gov/medlineplus/tutorials/lasik/htm/index.htm

http://www.isrs.org/

http://www.fda.gov/cdrh/LASIK

http://www.info.gov.hk/gia/general/200011/22/1122178.htm

http://www.hksh.org.hk/


Appendix 2: Investigation Guide

This part describes the procedures for preparing the materials and set-up used in the LASIK simulation investigation.

To make an eye without a cornea

1. Cut out a small circular hole of about 1 cm from the centre of a piece of black plastic film.

2. Wrap a glass biconvex lens of focal length 5 cm and diameter of 5 cm so that the hole lies on the centre of the lens. (Figure 1).

A model eye without a cornea



To make a model cornea

1. Dissolve 8 g of gelatin in 100 cm3 of water at about 80C. (Do not boil, it will denature/decompose the gelatin)

This 8% gelatin solution is used to prepare the cornea mold.

Notes:

Purity of the gelatin from different suppliers may vary. A slightly higher percentage may be needed for a tough and elastic cornea.

Pure gelatin can also be conveniently bought from most supermarkets, e.g. Robertsons pure gelatine is a good choice for this purpose.

2. Pour about 50 cm3 of the solution into an evaporating dish.

3. Make a circular ring by bending a piece of wire with plastic coating of thickness about 2.5 mm.

4. Fit this ring to the inner diameter of the top edge of the evaporating dish.

This ring acts as a support for another evaporating dish to sit on top of the first evaporating dish to form the cornea into a

convexo-concave shape when the gelatin solidifies.



5. Once the solution solidifies, a hemispherical shell of thickness of about 7 mm will be formed (Figure 2).

Notes for step 2-5:

New or thoroughly cleaned evaporating dishes should be used. A very thin layer of cooking oil or Vaseline on the inner surface of the

lower evaporating dish and the bottom surface of the upper evaporating dish should be used. This should make the removal of the cornea

from the dishes much easier. After removing the upper dish, the cornea should be taken out careful by gently pressing with fingers on one

side of the gelatin shell. It takes several hours for the solution to set at room temperature. Prepare the corneas and store them in a

refrigerator one day before the investigation.

The cornea moulded by two evaporating dishes from a solution of gelatin



Additional tips for preparing model cornea

1. Slight damage to the cornea should not affect the investigation.

2. The cornea which has been used for investigations can be re-used. Re-form a smooth surface by dripping a small amount of molten

gelatin on its cool surface



Notes for reshaping the model cornea

Any tool could be a good tool for reshaping the cornea as long as it can

flatten the surface of the cornea for correcting short-sightedness

make a donut shape on the surface of the cornea for correcting long-sightedness

For example, we may use a heated spatula to flatten the cornea and a ring-shaped metal wire (made by altering the shape of an

ordinary metal wire) to make a donut shape on the cornea.

We suggest the students can use a gas-lighter or a beaker of hot water to heat up the tools for reshaping the cornea.

A heated spatula is used to flatten the cornea A ring-shaped metal wire / stirrer is used to make a donut shape on the cornea



Appendix 3: Lesson Plan

Activity 1: Warm-up RevisionTime Intended Learning Outcomes Teaching Flow Materials Remarks

20 min

Revise the following: The structure of the eyes. Refractive errors: short-sightedness, long-

sightedness and astigmatism.

Know that the lens is not the only part of the eye refracting light rays.

Teacher conducts a quick survey in class to let the students be aware of the need and frequency of using aids to correct refractive errors.

(PowerPoint Slide 1-2 are shown)

Teacher asks the students to estimate the number of people at their age have short-sightedness in Hong Kong.

(PowerPoint Slide 2-3 are shown)

Students are given the worksheets of activity 1 and do the exercises in page 1 and 2.

(PowerPoint Slide 4 is shown)

Teacher asks questions about short-sightedness and long-sightedness and introduces the terms “refractive errors” on page 3 to the students.

Students read the paragraph “Refractive errors” and do parts 3 and 4.

Students think about the question: “Is the lens the only part refracting light in the eyes?” This is the transition question to activity 2.

PowerPoint Slice 1 to Slide 3.

Activity 1 worksheets.



Activity 2: Let’s try out “eye surgery” in the laboratory!



Time Intended Learning Outcomes Teaching Flow Materials Remarks

60 min

Understand how LASIK corrects short-sightedness and long-sightedness through the simulation investigation and video demonstration.

Apply creativity in a scientific investigation. (through the parts that require the students to design methods to reshape the model cornea)

Link up the investigations they do in laboratory to popular modern technology.

Teacher explains what LASIK is and the objective of the investigation is to simulate the LASIK operation. (PowerPoint Slide 5-6 are shown)

Part 1. Initial Setup (PowerPoint Slide 7 is shown) Teacher helps the student to understand corresponding

parts of eyes simulated: i. Gelatin “mold”: Cornea ii. Illuminated letter “F”: Object in front of eye iii. Movable stand with screen: Image on retina

Part 2: Simulation of correcting short-sightedness(PowerPoint Slide 8 is shown) Students have to design how to reshape the cornea so that

it can refocus the image back to the “retina surface”. Students do the questions on page 5 of the worksheet.

Part 3: Simulation of correcting long-sightedness(PowerPoint Slide 9 is shown) Students have to design how to reshape the cornea so that

it can again refocus the image back to the “retina surface”. Students do the questions on page 6-7 of worksheet.

Teacher shows PowerPoint slide shows and video demonstration that carry out the real LASIK.

(PowerPoint Slide 10 – 14 are shown)

Teachers explain the requirements of the Information Search exercise to students.

PowerPoint Slide 5 to Slice 14.


The details of preparing ‘eye’ and ‘cornea’ could be found on the last part of this book – Notes for technician.

There could be some other ways to reshape the cornea apart from the suggested methods in the teacher’s book. Teacher can encourage the students to try different methods.

A light touch on the cornea by

the heated spatula will shift the image drastically. It is advisable to follow the image throughout the investigation and keep it in focus.

Usual precautions for heating should be applied in the investigation. (Wear safety goggles)

The emphasis of this investigation is to enable the students to learn through the process rather the results. Report of failure should not be handled negatively.



Activity 3: Learning more about the nature of science (NOS) through the development history of refractive surgery.Time Intended Learning Outcomes Teaching Flow Materials Remarks

20 min

Learn more about the nature of science through thinking about the following questions:

“What motivates scientists to do research and to make invention?”

“Does science lead technology or does technology lead science?”

“Apart from the hard work and understanding of scientists, what factors are also critical to the birth of new knowledge through science

Students are given the worksheets for activity 3 and do the questions. (PowerPoint Slide 15 is shown)

Teachers discuss the answers with the students. Notes for Q3, Q3 and Q5 are listed below.

Q3 NOS point: The birth of most scientific knowledge such as LASIK is triggered by people’s desire to improve living standards and solve some important problems such as the need for good vision.

Q4 NOS point: Science not only leads technology, but sometimes/often technology leads science. In the case of LASIK, the technology of laser development is critical for the application of LASIK, so is computer control to drive the laser so accurately. But lasers are a product of scientific work.

Q5 NOS point: There are many factors critical to the birth of scientific knowledge such as political factors, government policy, economic factors, culture, value and the availability of research funds.

PowerPoint Slide 15 - 20.




Activity 4: Making Informed Decisions - Is LASIK for everyone?Time Intended Learning Outcomes Teaching Flow Materials Remarks

40 min

Understand the requirements of a suitable candidate/patient for LASIK.

Understand the risks associated with LASIK.

Be able to make cost and benefits analysis while making decisions.

Improve communication and presentation skills.

Express personal opinions on controversial scientific issues.

Students are given the worksheets for activity 4.

Students share the information they searched before and use it to finish the first exercise.

Students discuss the requirements and the risks associated

with LASIK in groups. Teacher collects and summarises discussion points.

(PowerPoint Slide 21 – 24 are shown)

Discussion Time: Teacher divides the students into five groups, each assigned a scenario in the table in page 12. Students discuss which correction method for refractive errors should be used.

Presentation Time: One representative from each group presents their suggestion in front of class. Audience can agree or disagree, but must give reasons concerning the choices and should suggest alternative answers.

Expressing your view: Students are encouraged to express their views in writing on the two questions on page 13 for homework, and present a few ideas in class.

PowerPoint Slide 21 to 24.


Teachers can guide the students to search and filter information from Internet. Also pay attention to the validity of the information they found (e.g. pay attention to the sources and origin of the information they find on web, commercial or research? selling or advising only?)

During the presentation time,

all students are encouraged to challenge the presenters on their choices.



Activity 5: Judging Advertisements (Truth and Honesty)Time Intended Learning Outcomes Teaching Flow Materials Remarks

20 min

Thinking critically and applying scientific understanding to judge the fairness of advertisement for LASIK procedures.

Students are given the worksheets for activity 5. (PowerPoint slide 25 is shown)

Students read the promotional material from an eye-centre and then answer the questions.

Students discuss their answers. Teachers help the students

to think more critically to judge those exaggerated advertisements. Balanced information is needed for informed decision making, what should be contained for a set of “balanced information”?

PowerPoint Slide 25.


Extra reading “Report on LASIK in U.K.” can be given to students if the teacher finds it suitable for them.


LASIK - New Senior Secondary Curriculum Goals: NOS...

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