Tuesday, December 28, 2010

RETINOSCOPE


Let's discuss about movement of retinoscopy reflects. How does it optically formed as against movement for myope eyes and with movement for hyperope eyes?

Please ignore the questions below. I have not deliver lecture for that topic yet.

working distance 2/3m, ocular refraction,

K of (i)+10D, (ii)+1D, (iii)-10D, (iv)-1D, and (v)-1.5D
 

57 comments:

  1. From my understandin.

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  2. muhammad hazwan razakDecember 29, 2010 at 8:58 PM

    slm...sory...actually what is the topic that we need to discuss here??i'm forgot the quetion.

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  3. i dont understand the qeustion,and what to discuss actually? is it to find dioptic power?,
    K= 1/k,
    k is working distance..
    so 1/2/3 = 1.5D
    but i dont knw wheather it is -ve o +ve.
    correct me if im wrong . tq

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  4. i dnt think that we hv to find dioptic power..sir didnt mention it in class if i'm not mistaken..
    i think we need to discuss 'bout movement o reflex..wallahua'lam..

    sori sir if i'm wrong..

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  5. actly, i'm not sure what the question want... but, if i'm not mistaken, from my understanding,
    working distance lens=1/working distance

    refer to da question,
    working distance lens=1/2/3
    =+1.5 D

    there r 2 situation:
    1) if ocular refraction,K < working distance lens,
    AGAINST movement is detected and da patient is having MYOPIA
    -so, we must use -ve lens to correct it

    2) if ocular refraction,K > working distance lens,
    WITH movement is detected and da patient is having HYPEROPIA
    -so, we must use +ve lens to correct it

    in this case,K of
    (i)is having 1st situation because its working distance lens is higher than +1.5D
    otherwise, (ii),(iii),(iv),(v) are having 2nd situation because they r lower than +1.5D

    ~show me da truth if i'm wrong~

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  6. salam for all of u.
    K of (i)+10D, (ii)+1D, (iii)-10D, (iv)-1D, and (v)-1.5D

    corrct me if i am wrong.
    i think BR MUZIMAN means.
    what is the ocular refraction if we do the retnoscopy withe working distance lens +1.5 ?
    From my understandin:
    for 10D when we remove the working distance lens
    the final ref will be +8.5D
    for +1D ----> - 0.5D
    for -10D ----> -11.5D
    for -1D -----> -2.5D
    for -1.5 ----> plano ~x(
    i hope u understand me .salam for all of u.
    K of (i)+10D, (ii)+1D, (iii)-10D, (iv)-1D, and (v)-1.5D

    corrct me if i am wrong.
    i think BR MUZIMAN means.
    what is the ocular refraction if we do the retnoscopy withe working distance lens +1.5 ?
    From my understandin:
    for 10D when we remove the working distance lens
    the final ref will be +8.5D
    for +1D ----> - 0.5D
    for -10D ----> -11.5D
    for -1D -----> -2.5D
    for -1.5 ----> plano ~x(
    i hope u understand me .:D

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  7. To all 1st year,

    please follow this blog using Google friend connect and networked blog & Like box using your FB account

    please do it before submit your tutorial

    ReplyDelete
  8. Awatif Akmal ArshadDecember 30, 2010 at 7:24 PM

    Hyperope: which have with movement of light

    when shine the retinoscopy light, light pass working distance length, and pass through patient pupil and projected on fundus,fundus act as screen then reflect the light to retinoscopy of examiner eye... the image will form at the back of our eye... image call the far point right??? so far point is at the back of the eye.... the image form called image of the image.

    myope: which have against movement of light
    the image form fall infront of examiner eye. so the far point is in between of examiner and patient eye.

    ~x( again correct me if im wrong.

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  9. Let's discuss about movement of retinoscopy reflects. How does it optically formed as against movement for myope eyes and with movement for hyperope eyes?


    salam
    from my view, i think because the myopic eyes the image locatrd behind the eye .and we will see the reflection of the image not real. so we will see it against movemant.

    also for hyperopic eyes becausethe image locatrd infront of the eye .and we will see the reflection of the image real. so we will see it with movemant. wallah aalam
    corrct me if i am wrong

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  10. nuur hani khairuddinDecember 31, 2010 at 2:31 PM

    myope:

    From retinoscope, light enters the patient eye's and illuminate the patient retina. Then the observer see the image focusing at the far point in FRONT of the patient's eye. So the reflex or image will move in an AGAINST direction of light from retinoscope.


    hyperope:

    From retinoscope, light enters the patient eye's and illuminate the patient retina. Then the observer sees the image at the far point of the patient's eye that is BEHIND the patient eye. So the reflex or image will move in the SAME direction of the light from retinoscope.

    correct me if im wrong..

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  11. Discussing bout movement of reflex..

    By observing the light, there are 3 conditions that can be determined. They are myopia, hyperopia and emmetropia.

    There are 3 types of movement:
    a) WITH
    b) AGAINST
    c) NEUTRALITY

    Patient’s refractive error influences the movement of reflex.

    With movement:
    Light is directed into the eye and the movement of the reflex is observed. If the reflex moves in the same direction as the retinoscope, this is called with movement.the patient is said to have hyperopia. Positive lenses is used to correct the hyperopia. When refracting a hyperopic eye, the examiner sees the reflex at the far point of the patient's eye which is behind the patient’s eye. So, the reflex will now move in the same direction as the image on the retina and the retinoscope's light on the outside of the patient's eye.

    Against movement
    If the reflex moves in the opposite direction to the retinoscope, this is called against movement. Negative lenses is used to correct this refractive error. When refracting a myopic eye, the examiner will see the reflex at the far point before the patient’s eye.

    Neutrality
    For neutrality, the pupil of the patient is filled with light and no movement occur. Neutrality of the reflex occurs when the far point of the patient's eye coincides with the cornea of the examiner's eye.

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  12. Wan Nur Amalina Wan A. Latif (^_^)December 31, 2010 at 10:21 PM

    A little bit about the reflex movement of the retinoscope (ret)..

    The light from ret is shone into the eye and reflected by the retina. The image of this reflection, known as reflex will move either in the same direction as the intercept(with movement) or in the opposite direction(against movement). The direction of the movement is dependent on where the far point of the image is in relation to the retina.

    answers for the question:

    For myope eye, the far point will falls between the eye being examined and the ret, the light rays will cross, the image will become inverted at ret and against movement is seen. This can be neutralized by using -ve lens.

    For hyperope eye,we can see the with movement as the far point will beyond the ret,since the light not come to the focal point, the rays have not crossed and therefore,are not inverted.
    This can be neutralized by +ve lens.

    correct me if i'm wrong..:)

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  13. This comment has been removed by the author.

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  14. Salam..followings are my answer for this discussion based on personal understanding. Do correct me if I did any mistakes.thanks;)

    Answer:
    When the light is shine into the eye which is not far-sighted nor near-sighted,the light hit the back of the retina at a single point and reflection will come back outside the eye. Wherever you direct the light to,the reflection will keep stationary.In this case,we had discovered the neural point.

    In case for a hyperope eyes,the light will focus on behind the patients's eyes indicating the far point of the eyes. As the retinoscope light is moving up and down,the light bouncing on the retina will also goes the same direction as the light goes which is the "with motion".Thus,a positive lens is required to focus the light directly on the single point of the retina and obtain the neutral point for a right prescription.

    While in case of a myopic eyes,the light shine into the eyes will focus in the middle of the eye as the far point lies between the examiner's eye and the patient's eye and the reflection that goes on the retina will be in opposite direction from the light forming like a see-saw action.Here,you will observe an "against movement" reflection in the patient's pupil.Thus,a negative lens is required in order to focus the light onto the retina and getting the right prescription for the patient's eyes.

    ;))

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  15. Sorry for my clumsiness,some correction here.:p

    When the light is shine into the eye which is not far-sighted nor near-sighted,the light hit the *back of the retina at a single point and reflection will come back outside the eye.

    *the light will hit on the retina

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  16. muhammad fahmi ananJanuary 1, 2011 at 3:36 PM

    salam to all of you. nice to meet you here. hope we can discuss and share our knowledge here.
    since we are still students it is does not matter if our opinions are not correct. just try to come out whats in your mind.okay?

    okay thats all for my intro.haha

    pertaining to our discussin, i cant get the idea from the question.
    anyone can help me explain the question?
    thanks~

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  17. @muhammad fahmi anan

    hi! nice to u too..hahaha..=))
    basically sir asked us to discuss about the reflex movement which are "neutal","with", and "against". We need to explain the formation of these 3 reflexes regarding to the case either myope/hyperope.While the question(yellow highlighted),just ignore it but better be ready whenever sir asked for the answer,ok!=)

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  18. salam..lets discuss

    Hyperopic patients
    -Light focuses at a point behind the
    retina
    -Streak movement in the same direction
    DISPLAYS WITH ( retinoscope as the
    MOTION)
    -Add plus lenses to bring the focusing
    point up to the retina

    Myopic patients „
    -Light focuses at a point before the retina
    -Streak movement in the opposite
    (DISPLAYS retinoscope direction as the
    AGAINST MOTION)
    -Add minus lenses to move the focal point
    back onto the retina

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  19. muhammad fahmi ananJanuary 2, 2011 at 5:44 PM

    @Nur Rozainie Abdullah

    oh..thanks zai. u looks so excited btw.

    hmm thats right. refer back to the question, what does the word 'optically formed' means?
    in what aspect should we explain actually?

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  20. This comment has been removed by the author.

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  21. hyperope eyes:the ray from RET form an unfocused horizontal filament image on the retina of the patient that acts as a new object with its image behind the retina.when the RET is tilted,the object(Retina) move down & the image(Reflex) also move down and vice versa..this is seen as "with movement".
    correcting:add +ve lense

    myope eye:if the RET is place beyond the payient's far point& swept from side to side across the pupil, the light reflex seen inside the pupil appears to sweep in the OPPOSITE DIRECTION as the streak emitted from the RET.
    this is called "against movement".
    correcting: add -ve lense

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  22. Nasrul Hadi Mohd SanadiJanuary 2, 2011 at 8:20 PM

    please recite doa before read my comment..:D

    myopic:when the ray is light on the retina,
    the observer can see the point focus in front of the macula.As the retinoscope is tilted,the image reflex move against direction with patch of light move from RET.So we need some -ve power to correct the focus

    hyperope:The point focus form at the back of the macula.As the RET is tilted,the image reflect move same direction with a small patch of light from RET.We need +ve power to correct it..

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  23. (With Movement);for hyperopic eye

    The image of the object will be formed behind the retina.
    When light from the retinoscope moves upward, the retina will illuminate in an upward direction forming the virtual and upright image in retina which is also in an upward direction. The movement is known as WITH movement due the image moves in the same direction as the retinoscope.
    Plus lenses will be placed in front of the patient’s eye to neutralise WITH movement.

    (Against Movement); for myopic eye

    The images of the object will be formed in front of the retina.
    When the examiner moves the illumination light upward, the retina will illuminate in an upward directions forming the real inverted image in the retina which will be focused between the patient and examiner. The retinal image appears to move downward which isopposite to the movement of the retinoscope. This is known to be the AGAINST motion.
    Minus lenses are placed in front of the patient’s eye to neutralise AGAINST movement.

    Neutral Movement

    When the pupil is filled with the light and there is no movement of the rest reflex during sweeping. It is called the neutral point.

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  24. salam to all..
    based on my understanding,here the answers for the discussion:

    Against movement for myope eyes:
    -as the light from the retinoscope enters the myopic eye, the reflex will move in opposite direction to that the light beam is swept.This occurs as the light enters the eye focusing at a point before the retina.For this case,negative power lens required in order to bring the focus onto the right point on the retina and correct the focus.

    With movement for hyperope eyes:
    -the reflex will move in the same direction with the retinoscope as the light is swept across the hyperope eyes.In this case,the light enters the eye will focus at a point behind the retina.The positive lens is used to neutralize the error which means to focus the light to the correct point on the retina.

    In neutrality,the light enters the eyes will focus at a point on the retina.So,as the light from the retinoscope is swept across the pupil,no movement of reflex will occur.

    *do correct me if im wrong ya ;)

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  25. syazwan hafiz mohdJanuary 2, 2011 at 10:46 PM

    bismillahirrahmanirrahim....dO smile while reading my opinion peeps....hhaa

    Let me first define what retinoscopy is.Retinoscopy is the method or process to determine the refractive error of the eyes by using retinoscope.This process needs the present of retinoscopist to determine the level of refractive error of the patients' eyes.

    Based on the question,we could say that the patient is myope(near-sightedness)when the movement of the patch of light projected from the retinoscope is visible as against-movement when is viewing by retinoscopist.This is because when the patch of light from the retinoscope is moved down,the movement of this light on the patient's retina(retinal image)is also moved down.This retinal patch is now acts as the object for the retinoscopist's eye and known as aerial image.Since it's myopic eye,the aerial image is formed in front of retinoscopist's eye in the opposite direction of the retinal image of the patient(move up).Then,this aerial image is detected as a blurred image on retinoscopist's retina of aerial image and move down.Since the retinoscopist inverts everything seen on his or her retina,the downward movement of the blurred image formed on the retina is interpreted as upward movement,which is against movement of the retinoscope patch of light.

    Same goes to the hyperopic eye(far-sightedness).When the patch of light from retinoscope is moved downward,it's detected as the same movement on the patient's retina.Since it's hyperope,the aerial image formed from the retinal patch strike at the back of the retinoscopist's retina and is in the opposite direction of the retinoscope's light(upward movement).As the blurred image of the aerial image formed on the retinoscopist's retina is upward,the retinoscopist will interpret the image formed on the retina as with movement(downward).

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  26. Nur Farrahin Mohd Nor KamalJanuary 2, 2011 at 11:08 PM

    for myopia(against movement)
    -against movement occurs when the reflex moves in the opposite direction to the light ray
    -Far point lies in front of pt's eyes that is between pt's eyes n examiner,light ray will cross n the image will become inverted at the retinoscope.
    -neutralize with positive lens

    for hyperopia(with movement)
    -occur when the light ray is moved downwards and the reflex in the pupil also moves in the same direction
    -Far point lies behind the retina,the light rays doesn't cross and the image become upright.
    -neutralize with minus lens

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  27. Nur Farrahin Mohd Nor KamalJanuary 2, 2011 at 11:12 PM

    oppss some corrections for the above comment
    * myopia pt treated with minus lens n hyperopia pt treated with positive lens..

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  28. Muhammad Jazli Che Mohd AriffJanuary 2, 2011 at 11:55 PM

    salam...hi guys...
    regarding to the question....
    as all of your answers quite similiar , what can i conclude here is:
    hyprope eye:
    -light focus on behind the patient's eyes
    -when the retinoscope light is moving up & down and is directed into the eyes,the reflex light moves in the same direction as the retinoscope.
    -formed as with movement
    -can be neutralized by +ve lenses to focus the light directly on the single point of retina
    myopes eyes:
    -light from RET comes to a focus in front of retina
    -When the RET is tilted,the reflex light seen inside the pupil moves opposite direction to the RET light
    -formed against movement
    -use -ve lenses to correct it.
    tq....
    *do correct me if im wrong.....

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  29. Salam…In general..retinoscopy is a simple, objective means of obtaining the refractive error of an eye. It composed of a single lens, alight source and a mirror. It is able to recognised whether the patient’s retina is focused in front of , at or behind patient own eye.
    Regarding to the question….in my words..for the first case, that is myope, it is understand to be formed against movement. When the plane mirror retinoscope is tilted down the patch of the light (the light that formed upon the fundus) also moves down. So this patch will become the object in this case. Then it will produce the aerial image of the retinal patch that formed in front of the retinoscopist’s eyes and this aerial image moves in the opposite direction of the patch of the light. After that the aerial image now becomes the object for refraction at the retinoscopist’s eye. It will result in blurred image of the aerial image in myope to be in upward that is against the blurred image on retinoscopist’s retina.
    For the second case, that is hyperopia.The differences with the first case are the blurred image that formed on retinoscopist’s eye. But the aerial image of the retinal patch formed behind of the retinoscopist’s eye. In short, the blurred image of the aerial image formed on the retina of the retinoscopist’s is as same direction with aerial image in the hyperope.
    So..thats my opinion..i hope for comment from my fellow friends and lecturer to correct my understanding on this topic..tq

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  30. @quedin's

    You are allowed and encouraged to use your Google account in this comment section

    ReplyDelete
  31. @Roxy zai

    You are allowed and encouraged to use your Google account in this comment section

    ReplyDelete
  32. syazwan hafiz mohdJanuary 3, 2011 at 12:10 AM

    spe2 boley bg ak tuisyen diz course???ak nk jd pandai..:-t

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  33. Nasrul Hadi Mohd SanadiJanuary 3, 2011 at 12:14 AM

    syazwan can u speak english..im not understand what are you talking about..;)

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  34. kO tnye ajew fahmi!!!!!ak pn booley ajar kO la;;)

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  35. muhammad fahmi ananJanuary 3, 2011 at 12:17 AM

    weh3!!!!!kOrang ingt ni fb kew????cdey ak bce opinions korang ni la....:((

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  36. nurjannah ngatimanJanuary 3, 2011 at 3:03 PM

    bismillahirrahmanirrahim…

    since many of our friend have quite similar comments, I want to give in a quite different way.

    refer to the question, how does movement of RET’s reflects optically formed as:
    -AGAINST movement for MYOPE eye?
    -WITH movement for HYPEROPE eye?

    before we go deeply, let’s look to 4 principles of RET:
    1.the instrument is moved
    2.working at specific distance
    3.RET access reflected light (patch of light) in terms of:
    -size
    -movement
    -speed
    -brightness
    4.fundus act as fixed screen as the direction of the light:
    light of RET>patient’s pupil>patient’s fundus>patient’s pupil>retinoscopist’s eye

    fundus image can indicates the behavior of reflects either:
    -WITH movement
    -AGAINST movement
    -NO movement

    for MYOPE and HYPEROPE,
    image formed is out-of-focus patch of light upon the patient’s fundus while for EMMETROPE, the image formed is focus on the fundus.

    MYOPE:
    -a blurred image of the aerial image located IN FRONT of the fundus.
    -the aerial image has an OPPOSITE direction with the retinal image as it called AGAINST movement
    -must use –ve lens to make sure the image formed on the fundus

    HYPEROPE
    -a blurred image of the aerial image located BACK of the fundus.
    -the aerial image has an SAME direction with the retinal image as it called WITH movement
    -must use +ve lens to make sure the image formed on the fundus

    ~show me da truth~

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  37. Assalamualaikum.
    let's share...
    1)hyprope's eye
    -Occurs when rays from distant axial object point focus ‘behind’ the macula, M’ in unaccommodated eye.
    -When retinoscope light is move up and down and is directed into the eye,the pupil inside the eye will move as SAME direction as retinoscope light.
    So it's WITH movement.
    -It can be corrected by using positive power

    2)Myope's eye
    -Myope is when Distance ray of object point focus in front of the macula in the unaccommodated eye.
    -when retinoscope lihgt come to focus in front of retina.
    - retinoscope light is tilted and move in OPPOSITE direction as retinoscope light.
    -So it's AGAINS movement
    -It can be corrected by using negative power.

    ----->correct if i'm wrong

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  38. Noor Asma" binti Mohamad NoorJanuary 3, 2011 at 4:02 PM

    Assalamualaikum.
    let's share...
    1)hyprope's eye
    -Occurs when rays from distant axial object point focus ‘behind’ the macula, M’ in unaccommodated eye.
    -When retinoscope light is move up and down and is directed into the eye,the pupil inside the eye will move as SAME direction as retinoscope light.
    So it's WITH movement.
    -It can be corrected by using positive power

    2)Myope's eye
    -Myope is when Distance ray of object point focus in front of the macula in the unaccommodated eye.
    -when retinoscope lihgt come to focus in front of retina.
    - retinoscope light is tilted and move in OPPOSITE direction as retinoscope light.
    -So it's AGAINST movement
    -It can be corrected by using negative power.

    ----->correct if i'm wrong

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  39. nurjannah ngatimanJanuary 3, 2011 at 4:03 PM

    bismillahirrahmanirrahim…

    since many of our friend have quite similar comments, I want to give in a quite different way.

    refer to the question, how does movement of RET’s reflects optically formed as:
    -AGAINST movement for MYOPE eye?
    -WITH movement for HYPEROPE eye?
    before we go deeply, let’s look to 4 principles of RET:
    1.the instrument is moved
    2.working at specific distance
    3.RET access reflected light (patch of light) in terms of:
    a.size
    b.movement
    c.speed
    d.brightness
    4.fundus act as fixed screen as the direction of the light:

    light of RET>patient’s pupil>patient’s fundus>patient’s pupil>retinoscopist’s eye

    fundus image can indicates the behavior of reflects either:
    -WITH movement
    -AGAINST movement
    -NO movement

    for MYOPE and HYPEROPE,
    image formed is out-of-focus patch of light upon the patient’s fundus while for EMMETROPE, the image formed is focus on the fundus.

    MYOPE:
    -a blurred image of the aerial image located IN FRONT of the fundus.
    -the aerial image has an OPPOSITE direction with the retinal image as it called AGAINST movement
    -must use –ve lens to make sure the image formed on the fundus

    HYPEROPE:
    -a blurred image of the aerial image located BACK of the fundus.
    -the aerial image has an SAME direction with the retinal image as it called WITH movement
    -must use +ve lens to make sure the image formed on the fundus

    ~show me da truth~

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  40. nuur hani khairuddinJanuary 3, 2011 at 9:31 PM

    salam...
    from my obsevation n reading all ur comment...
    i got confused...
    what are the term/ important element in retinoscopy....
    can anyone explain it to me...
    thanks...

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  41. muhammad fahmi ananJanuary 3, 2011 at 11:12 PM

    okay..

    myope=near-sightedness=rabun jauh

    then the light focus in front retina

    thats why we need negative lens=convex lens

    to focus the light back to retina

    same goes to hyperope but in opposite way

    hyperope=far-sightedness=rabun dekat

    light focus at the back of retina

    thats why we nned positive lens=concave lens

    to diverge light to retina

    thanks.

    tolong betulkan jika ada tersalah kata2. ;))

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  42. Awatif Akmal ArshadJanuary 4, 2011 at 1:44 AM

    Let's discuss about movement of retinoscopy reflects. How does it optically formed as against movement for myope eyes and with movement for hyperope eyes?
    making some edit:
    from my understanding...
    Hyperope: which have with movement of light

    when shine the retinoscopy light, light pass working distance length, and pass through patient pupil and projected on fundus,fundus act as screen then reflect the light to retinoscopy of examiner eye...
    -the image on the retina of patient's eye acts as new object then will form image behind the retina...so, the examiner will see the reflex at far point of patient eye which it is behind the eye..
    -far point is point that we can see the object clearly.(correct me if im wrong)


    myope: which have against movement of light
    the image form fall infront of examiner eye. so the far point is in between of examiner and patient eye.so, if it is outside the far point, it gives against motion of light.

    *again correct me if im wrong.

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  43. muhammad hazwan razakJanuary 4, 2011 at 4:24 AM

    wow.. good job everyone....

    for myope eye:
    we know basically image will form infront of the eye real inverted.so when we move RET downward image Form also downward
    (now the light become an object for retinoscopy)

    retinoscopy invert everything seen on his or her retina...when we see the movement of retinoscopy reflects is upward..so the movement of RET not same like RET reflect ..that why it againt movement mcm tu ke???????


    but it different in hyperope eye:
    the image basically will form behind the retina virtual and upright,so when we move RET downward image Form in retina will Upward
    now image in retina become object to RET.we can see retinoscopy reflects is downward...so the movement of RET same like the RET reflect

    it's true????
    please correct me if i'm wrong because this is what i'm understand

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  44. muhammad hazwan razakJanuary 4, 2011 at 4:26 AM

    mcmtu ke = like that ke?? :))

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  45. @muhammad fahmi anan

    negative lens = concave lens

    positive lens = convex lens

    heheh...

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  46. SUYIDATINA BT SULAIMANJanuary 4, 2011 at 5:29 AM

    Q.1)MOVEMENT OF RETINOSCOPY REFLEX

    1)“WITH” MOVEMENT
    -when the reflex moves in the same direction as the sweeping motion of the ret streak.

    2)“AGAINST” MOVEMENT
    -when the reflex moves in the opposite direction to the sweeping motion of the ret streak.

    3)“NO” MOVEMENT/ NEUTRAL
    -when the whole pupil is filled with light
    -no ret reflex during sweeping
    -it is what we aim to get when doing ret coz when we’ve found the neutral point, we can estimate the person’s refractive error.

    4)“SCISSORS” MOVEMENT
    -very rarely seen
    -indicates that the person has irregular astigmatism
    -appearance of the movement:
    a)not “neutral”, “with” or “against”
    b)a double reflex that seems to rotate as the streak is swept over the pupil
    c)named scissors coz it looks like a pair of scissors opening & closing

    **SWEEPING: smooth, repetitive movement of the ret’s light across the person’s eye.



    Before I answer this question, let’s get some basic ideas how does ret functioned..

    -Retinoscope consists of a single lens, a light source and a mirror.
    -Ret will directs a beam of parallel/slightly divergent beam of light into the customer’s eye.
    - The light will illuminates the customer’s retina and is reflected back causing a reflex in the customer’s pupil (we called it fundus reflex).
    -The refractionist while observing the reflex in the customer’s pupil can determine the refractive condition of the customer’s eye by using trial lenses on a phoropter.
    - The trial/corrective lenses placed in front of the customer’s eye caused the reflected light to focus/conjugate to the pupil of the examiner’s eye.


    from my understanding (correct me if I’m wrong, sir n friends..)

    IN GENERAL
    -we’ll focus on two things (retinal image and aerial image).
    -retinal image is the real image formed on patient’s retina. It will become object for aerial image.
    -aerial image is the projected light patch from patient’s retina. It’ll become object for refraction at the retinoscopist’s eye.

    NORMAL CASES
    -for “healthy” eye, aerial image will form in the plane of the retinoscopist’s pupil thus the whole retinoscopist’s fov is illuminated simultaneously.
    -light leaving the eye is directed to infinity (move parallelly) thus conjugate to this retina.
    -image formed is clear.

    Q.2)HOW RET REFLEX OPTICALLY FORMED AS “AGAINST” MOVEMENT FOR MYOPE EYE?

    MYOPE EYE
    -has excessive refractive power (too much plus power).
    -rays come to a focus in front of the retina.
    -blurred aerial image of light patch formed in front the retinoscopist’s retina.
    -aerial image moves up and retinal image moves down.
    -as refractionist shines the light streak on customer’s eye in the vertical position and moves the light streak, the image reflex appeared to opposite the direction.
    - correct this by using minus lens.

    Q.3)HOW RET REFLEX OPTICALLY FORMED AS “WITH” MOVEMENT FOR HYPEROPE EYE?

    HYPEROPE EYE
    -deficient in refractive power.
    -point of focus is behind retina coz rays from infinity aren’t refracted enough.
    -light leaves the eye diverged as it came from a point behind the eye.
    -blurred aerial image formed behind the retinoscopist’s retina.
    -both aerial image and retinal image moves up.
    -as refractionist shines the light streak on customer’s eye in the vertical position and moves the light streak, the image reflex appeared to opposite the direction.
    -correct this by using plus lens.

    **BCOZ RETINOSCOPIST INVERTS EVERYTHING SEEN ON HIS/HER RETINA,the reflex is seen as moving "with" movement of the ret's mirror in hyperopia & "against" movement in myopia.

    ReplyDelete
  47. Assalamualaikum, encik muziman dan rakan2..

    Firstly, we must know the function of retinoscope. Retinoscope is used to detect abnormalities occur in patient's eye which are refractive error, astigmatism, pathology abnormalities and etc.

    For refractive errors, there are 3 conditions of the eyes which are hyperope, myope and emmetrope.

    From my understanding, we just apply the simple optics concept in determining the movement of reflection.

    1)hyperope.
    -known as far sightedness.
    -occur when image formed at the back of retina.
    -the nature of image is virtual and upright.
    -if the object is upward, image formed is also upward. It occur because the reflection of object at retina that focused the light in accordance to where the light is projected.
    -so, the reflection that can be seen via retinoscope is with movement.
    -hyperope can be corrected by negative lens or concave lens.

    2)myope.
    -known as near sightedness.
    -occur when the image formed in front of the retina.
    -the nature of image is real and inverted
    -if the object is upward, image formed is downward. It occur because of light is further travel after intersection at focal point in front of retina.
    -so, the reflection that can be observed via retinoscope is against movement.
    -myope can be corrected by positive lens or convex lens.

    3)emmetrope
    -it explain the condition of normal eye that directed the light to infinity.
    -no movement seen via retinoscope.

    That's all from me..
    Allah a'lam..

    ReplyDelete
  48. nurjannah ngatimanJanuary 4, 2011 at 6:46 AM

    bismillahirrahmanirrahim…

    since many of our friend have quite similar comments, I want to give in a quite different way.

    refer to the question, how does movement of RET’s reflects optically formed as:
    -AGAINST movement for MYOPE eye?
    -WITH movement for HYPEROPE eye?

    before we go deeply, let’s look to 4 principles of RET:
    1.the instrument is moved
    2.working at specific distance
    3.RET access reflected light (patch of light) in terms of:
    a.size
    b.movement
    c.speed
    d.brightness
    4.fundus act as fixed screen as the direction of the light:
    light of RET>patient’s pupil>patient’s fundus>patient’s pupil>retinoscopist’s eye

    fundus image can indicates the behavior of reflects either:
    -WITH movement
    -AGAINST movement
    -NO movement

    for MYOPE and HYPEROPE,
    image formed is out-of-focus patch of light upon the patient’s fundus while for EMMETROPE, the image formed is focus on the fundus.

    MYOPE:
    -a blurred image of the aerial image located IN FRONT of the fundus.
    -the aerial image has an OPPOSITE direction with the retinal image as it called AGAINST movement
    -must use –ve lens to make sure the image formed on the fundus

    HYPEROPE:
    -a blurred image of the aerial image located BACK of the fundus.
    -the aerial image has an SAME direction with the retinal image as it called WITH movement
    -must use +ve lens to make sure the image formed on the fundus

    ~show me da truth~

    ReplyDelete
  49. Siti Hawa Saadah HamdanJanuary 4, 2011 at 7:30 AM

    Bismillahirrahmanirrahim..assalamualaikum...may Allah bless all of us...

    straight to the question..
    from my understanding,the question is,how does the ‘with’ movement occur for hyperope and ‘against’ movement for myope eyes.

    for the first case,that is MYOPE

    -if the retinoscope is placed beyond the patient’s far point and swept from side to side across the pupil, the light reflex seen inside the pupil appears to sweep in the opposite direction as the streak emitted from the retinoscope.

    -how does this happen??
    1.A plane mirror retinoscope forms an out-of-focus patch of light upon the patient’s fundus. When the mirror tilted down,the patch of light also moves down.
    2.Patch of light become the object,then,an aerial image of retinal patch formed in front of retinoscopist’s eye.
    3.This aerial image moves in the opposite direction to the movement of retinal patch(if retinal patch moves down,the aerial image moves up)
    4.A blurred image of the aerial image formed on the retinoscopist’s retina.
    5.As the aerial image moves up the retinal image moves down.

    -we can correct this by using minus lens

    For the second case,HYPEROPE

    -‘with’ motion reflex of light comes into the shadow projected in the optical system from the aperture of the retinoscope. They form an unfocused horizontal filament image on the patient that acts as a new object with its image behind the retina.

    -For more understand how does this happen,
    1.A plane mirror retinoscope forms an out-of-focus patch of light upon the patient’s fundus. When the mirror tilted down,the patch of light also moves down.
    2.Patch of light becomes the object for a hyperope of less than 1.50D.
    3. An aerial image of retinal patch formed behind the retinoscopist’s eye and this aerial image moves in the opposite direction to the movement of the retinal patch.
    4.For hyperopic case, a blurred image of the aerial image is formed on the retina of the retinoscopist.
    5.As the aerial image moves up so does the blurred image upon the retinoscopist’s retina.

    -we can correct this by using plus lens.

    Because the retinoscopist inverts everything seen on his or her retina, the reflex is seen as moving ‘with’ the movement of the mirror in hyperopia and ‘against’ the movement of the mirror in myopia.

    ReplyDelete
  50. Siti Hawa Saadah HamdanJanuary 4, 2011 at 7:37 AM

    please correct me if i'm wrong
    ~learn from mistake~

    ReplyDelete
  51. @Amar Hanif

    Amar, near sightedness for myopic patient is right but then there is no such word as far sightedness in optics. Hyperopic patient kan see at distance so do at near but with the help of accommodation.. =)

    Kan sir kan? Hehe.

    ReplyDelete
  52. Mohd Syukri AminuddinJanuary 4, 2011 at 12:38 PM

    Let's discuss about movement of retinoscopy reflects. How does it optically formed as against movement for myope eyes and with movement for hyperope eyes?

    Assalamu'alaikum w.b.t to all,
    Sorry 4 the late response. Ok,i think it's just the simple concept can be understood regarding the question above..
    Focussing on these 2 conditions :
    1- MYOPIA- AGAINST MOVEMENT
    2- HYPEROPIA- WITH MOVEMENT

    Against movement
    -The reflex moves in the opposite direction to the retinoscope
    -The examiner will see the reflex at the far point before the patient’s eye
    -Neutralized by -ve lenses

    With movement:
    -The reflex moves in the same direction as the retinoscope
    -The examiner will see the reflex at the far point of the patient's eye which is behind the patient’s eye
    -Neutralized by +ve lenses

    More in4 related to discussion :
    http://www.icee.org/education2/student_manual/PDF_protected/16_Retinoscopy_Student.pdf

    ReplyDelete
  53. @Amar Hanif

    another correction,
    Hyperope can correct by plus lens and myope by negative lens.

    ReplyDelete

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