Retinoscopy - Procedure PDF

‫‪Objective Refraction‬‬ ‫)‪(Retinoscopy‬‬ ‫اسم المدرس‪ :‬د‪.‬إيثار البشتاوي‬ ‫اسم المساق‪ :‬العناية البصرية األولية ‪I‬‬ ‫اسم الكلية‪ :‬كلية الطب وعلوم الصحة‬ ‫‪1‬‬  Objectives Understand the types of refractive error (ametropia) Explain the...

‫‪Objective Refraction‬‬ ‫)‪(Retinoscopy‬‬ ‫اسم المدرس‪ :‬د‪.‬إيثار البشتاوي‬ ‫اسم المساق‪ :‬العناية البصرية األولية ‪I‬‬ ‫اسم الكلية‪ :‬كلية الطب وعلوم الصحة‬ ‫‪1‬‬  Objectives Understand the types of refractive error (ametropia) Explain the accommodation effect on vision in ametropes Realise the basic optical principles of retinoscopy Assess distance refractive error using retinoscopy Interpret the refractive data collected. Record data collected through out the eye exam in an accurate and efficient manner.  Outline Refractive error (RE) Types of refractive error Accommodation Retinoscopy the science What is retinoscopy? The retinoscope Optical principles – how does it work? The ret reflex Retinoscopy procedure When to do ret The steps to follow Procedure Set up Sph/sph method Sph/cyl method  Refractive error Refractive Components of the eye Emmetropia Types of spherical refractive error Accommodation Role Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Refractive components of the eyes Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Emmetropia 4 Refractive power and axial length Parallel light from infinite perfectly matched: image clear, no corrective lens required object focussed on the retina Object at Parallel 2 Convergent infinity light rays light rays 1 Light refracted by 3 Light focussed cornea and lens i.e. on retina refractive power (converging, convex , +ve) Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Refractive Errors Myopia 1 Refracted by cornea and lens 4 Either refractive power too strong or axial length too long Parallel light from infinite object focussed in front of the retina Object at Parallel infinity light rays 3 Blur circle at retina 2 Focussed 5 negative, concave, diverging, in front of retina corrective lens required to push focus back onto the retina Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Refractive Errors 1 Refracted by 4 Either Hypermetropia cornea and lens refractive power too weak or Parallel light from infinite object axial length too short focussed behind retina Object at Parallel infinity light rays 2 Light focussed behind retina 5 Positive, convex, converging corrective lens required to pull 3 Blur circle focal point forward to retina at retina  Refractive Errors Accommodation: As object comes nearer: 3 Focal point Emmetrope becomes blurred shifted Hypermetrope becomes more blurred backwards Myope becomes clearer (until focussed on retina, then becomes blurred) 1 Object at 2 Near infinity object 1 Parallel 2 Divergent light light 4 Blur circle at retina Refractive power unchanged  Refractive Errors Accommodation 3 Point of focus shifts forwards, blur circle decreases until point Accommodation allows: achieved Emmetrope to focus on near object (clear near and distance: but not at the same time!): Hypermetrope to focus on distant and (to lesser extent) near objects (clear distance and less-so near: as degree of 4 Distant object hypermetropia increases, now forms blur distance also becomes blurred). circle at retina Myope: only need to accommodate if object is closer 2 Becomes more than their far-point (clear near, Near object: 1 Increase refractive power by convergent distance blurred) Divergent light increasing lens power (cornea remains unchanged) Note: must now alter definitions of emmetropia, myopia and hypermetropia to include the phrase “when accommodation is relaxed” Retinocopy- the science What is retinoscopy? The retinoscope Optical principles – how does it work? The ret reflex  Retinoscopy Objective measurement of refractive error Starting point for subjective refraction Used to prescribe where subjective refraction can’t be performed Screening for ocular disease Keratoconus, media opacities Specialist retinoscopy (next semester) Accommodation stability Accommodative lag  Retinoscopy When should I do it? Everyone! It is an objective test May be the only way of determining refractive error for non- communicative or non-cooperative patients Children Non-English speaking Learning difficulties Malingerers Low vision Laboratory animals  The Retinoscope Eyepiece Light source On/off/brightness control Collar Moves up and down to change the vergence of the light Rotates to change the angle of the beam The Retinoscope How does it work?  The Retinoscope How does it work? In retinoscopy, the purpose is to inspect light moving across the fundus Clinician watches shape and movement of the light within the pupil (the ret reflex)  Retinoscopy Optical principle Clinician Patient S1 S2 The light in the pupil is called the “ret reflex” So  1. Neutral position: Far point conjugate with Patient Clinician S1 observers nodal point. No movement of reflex, S2 sudden change from red reflex to no reflex. Mirror tilts forwards Optical principle S2 Retinoscopy No effect on reflex Mirror tilts further forwards No S2 Reflex disappears Retinoscopy Optical principle Neutral Reflex  Far point behind observers pupil. Subject S1 Observer With movement of reflex, S2 gradual change from red reflex to no reflex Far point behind Within pupil observers pupil Mirror tilts forwards S2 Optical principle Reflex moves down, Retinoscopy Outside pupil i.e. with direction of movement of light Mirror tilts further forwards No S2 Reflex disappears Retinoscopy Optical principle With Movement  Far point in front of observers pupil. Against movement of reflex, Observer gradual change from red reflex to no Subject S1 reflex S2 Far point in front of Within pupil observers pupil Mirror tilts forwards Optical principle S2 Retinoscopy Outside pupil Reflex moves up, i.e. against direction of movement of light Mirror tilts further forwards Reflex disappears No S2 Retinoscopy Optical principle Against Movement  Retinoscopy Optical principle Degree of ametropia and the reflex As subject becomes more myopic, the cone of light becomes wider Greater portion of light falls outside of practitioner’s pupil, so dimmer reflex Greater excursion before reflex lost, so movement of reflex from seen to not seen becomes slower  Reflex Observation Meaning Brightness Dim Far from Rx Bright Close to Rx Streak size Narrow Far from Rx The Ret Reflex Wide Close to Rx Retinoscopy Movement With Need more plus direction Against Need more minus Movement Slow Far from Rx speed Fast Close to Rx  Retinoscopy The final goal Not quite! The general concept of ret is that we use lenses add lenses until we see “reversal” and then tweak this until we see “neutral”  Retinoscopy WorkingWorking distance distance We now have neutral Clinician Patient We have added lenses S2 We have also introduced negative vergence due to our working distance So to get neutral, we needed: (WD) lens power = Rx + 1/d = 1/d (m) Where d = distance in m, To get the right prescription measured between your we need to compensate ret and patient’s eye Rx = lens power – 1/d  Working distance compensation Adding the working distance lens For example WD= 50cm WD lens = 1/0.50 = +2.00DS Neutrality for the same patient is still +3.00DS WD lens = +2.00DS Rx = lens power - 1/d Lens power = +1.00DS  Summary RE are defined when accommodation is relaxed Retinoscopoy is an objective measurement of refractive error In order to assess RE using retinoscopy, watch the shape and movement of the ret reflex Add trial lenses added until the shape and movement reach a state called “reversal  Retinoscopy- the Procedure Set up Sph/Sph method Sph/Cyl method Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 1. Explain to the Pt. what are you going to do and why.. i.e Check the RE Dim the room light Fixate on dochrome chart Do not to look at the retinoscope light. Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 2. Measure your patient’s pupillary distance (PD) 3. Dial your patient’s PD into the trial frame and fit it to your patient’s face Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 4. Position the pt. comfortably in the examining chair 5. Set both eyes open 6. set the trial frame or phoropter at a vertex distance of approximately 12mm Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 7. Place a working distance (WD) lens in the back cell for the trial frame Lens power = 1/distance between retinoscope and your patients eye in metres Roughly the length of your outstretched arm Most of you will use a lens between +1.50 (67cm) and +2.00DS (50cm) Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 8. Position yourself at your correct working distance Stretch out your left arm and touch the trial frame This is your working distance (WD) – always check this Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 9. Illuminate a non-accommodative target Usually the duochrome ask your patient to look at the green light 10. Turn room lights off Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 11. Hold the retinoscope in you right hand and RE for patient’s RE (swap for LE) 12. Get as close to your patient’s visual axis as possible Your head should almost be in the way! Confirm this by asking your patient Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 13. Move the retinoscope collar (or streak rotator) so it is at the bottom 14. Turn the retinoscope on and rotate the collar so the light is vertical or horizontal Horizontal light Vertical light Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up NOTE: Break phenomenon If the axis is oblique, you will see the reflex tilted compared to the retinoscope light. Align the streak such that it is parallel to the reflex angle and neutralise along that meridian and at 90 to it. These will form your principle meridians. Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 15. Before examining an eye, check the reflex movement in the other eye Reflex movement need to be in against motion in all directions 90, 180, 45, 135 If it is not against Add + lenses in 1.00D step until Against is seen Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up 15. Shine the light into your patient’s right eye and observe the ret reflex Is there a high refractive error? Is the ret reflex bright/dim? wide/narrow? Slow/fast? Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Set-up Reflex Observation Meaning To reach endpoint Movement direction With Need more plus Against Need more minus Brightness Dim Far from Rx (more lenses needed) Bright Close to Rx (less lenses needed) Streak size Narrow Far from Rx (more lenses needed) Wide Close to Rx (less lenses needed) Movement speed Slow Far from Rx (more lenses needed) Fast Close to Rx (less lenses needed) Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- Procedure Sphere/Sphere Method Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method 1. Rotate the streak using the controls on the retinoscope horizontally examine the movement along the vertical meridian move it up and down. Against With movement movement Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method 2. Neutralize the first meridian move the light from side to side 3 or 4 times Add trial lenses in 1.00DS steps to the front cell of the trial frame until you see reversal ie. The light moves in the opposite direction) The refractive error will be somewhere between the last lens that shows the initial movement, and the first lens that shows the reversed movement Find neutrality using smaller steps i.e 0.25D steps Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method RE LE Example 1: +2.00 DS +2.00 DS With movement  Add plus +3.00 DS +2.00 DS With movement  Add more plus +4.00 DS +2.00 DS Against movement  Reversal Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method RE LE Example 1: +3.00 DS +2.00 DS With movement  Add plus +3.50 DS End Point With movement 2 Reversal +3.75 DS Against movement 1 +4.00 DS +2.00 DS Against movement  Reversal Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method RE LE Example 2: +2.00 DS +2.00 DS Against movement  Add minus/ reduce plus +1.00 DS +2.00 DS Against movement  Add more minus/reduce plus 0.00DS +2.00 DS With movement  Reversal  Retinocopy- the Procedure Sphere/Sphere Method RE LE Example 2: +1.00 DS +2.00 DS Against movement  Add minus +0.50 DS End Point Against movement 2 Reversal +0.25 DS With movement 1 0.00DS +2.00 DS With movement  Reversal Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method 3. Rotate the streak using the controls on the retinoscope Scope the ret streak in the pupil along horizontal (the streak vertical) move it from side to side along the horizontal meridian note the movement. Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method 4. Neutralize the second meridian move the light from side to side 3 or 4 times Add trial lenses in 1.00DS steps to the front cell of the trial frame until you see reversal ie. The light moves in the opposite direction) The refractive error will be somewhere between the last lens that shows the initial movement, and the first lens that shows the reversed movement Find neutrality using smaller steps i.e 0.25D steps Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method 5. Repeat for the left eye Always go back to check the first eye again use your left eye to neutralise the pt.’s left eye Need to control accommodation i.e. check that motion is against in all meridians (90,180, 45, 135) If not, add + lenses until Against is seen 6. Remove working distance lens, check vision 7. Record lens power and vision Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method. Recording -3.00 x 90 Example 1: -3.00@180 180 +1.50 x 180 Rx: +1.50/-4.50x180 - 90 +2.00 (WD, 50cm) ___________________________ -0.50/-4.50x180 +1.50@90 Final Rx: - + RE: -0.50/-4.50x180, VA: 6/6 Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Sphere Method. Recording +7.50 x 120 Example 2: +9.00 x 30 +7.50@30 Rx: +9.00/-1.50x30 - 120 +2.00 (WD, 50cm) ___________________________ +9.00@120 +7.00/-1.50x30 Final Rx: LE: +7.00/-1.50x30, VA: 6/6 - + Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinoscopy- Procedure Sphere/Cylinder Method Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method 1. Set up (steps 1-15) 2. Scope each meridian separately o i.e either horizontal first then vertical or vice versa Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method 3. Note which meridian is more (+) Remember! Reflex Observation Meaning To reach endpoint Movement direction With Need more plus Against Need more minus Brightness Dim Far from Rx (more lenses needed) Bright Close to Rx (less lenses needed) Streak size Narrow Far from Rx (more lenses needed) Wide Close to Rx (less lenses needed) Movement speed Slow Far from Rx (more lenses needed) Fast Close to Rx (less lenses needed) Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method Observations a. if you see one with and one against o neutralise with movement first Against With movement movement Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method Observations b. if you see 2 with movement o neutralise ‘slower with’ movement first With With movement movement Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method Observations c. if you see 2 against movements, o neutralise “faster against” first Against Against movement movement Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method 4. Neutralize the first meridian with spherical lenses (+ or -) Adding lenses in 1.00DS steps until reversal Try smaller lenses to find the endpoint Endpoint neutrality or 1st lens before reversal Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method 5. Scope the second meridian, you should see (Against movement) If your assumption of the more plus meridian was correct Neutralise the second meridian with cyl lenses In 0.25 DC steps Endpoint neutrality or 1st lens before reversal Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method 6. Repeat for the left eye Always go back to check the first eye again use your left eye to neutralise the pt.’s left eye Need to control accommodation i.e. check that motion is against in all meridians (90,180, 45, 135) If not, add + lenses until Against is seen 7. Remove working distance lens, check vision 8. Record lens power and vision Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method.. Recording & Final Rx. Example: -2.00DC x 90 90 +3.00DS@90 +3.00 x 180 Rx: +3.00/-2.00x180 - +1.50 (WD, 67cm) ___________________________ +1.50/-2.00x180 180 -2.00 DC@180 Final Rx: RE: +1.50/-2.00x180, VA: 6/6 Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Sphere/Cylinder Method.. Recording & Final Rx. - 5.50 DS x 115 Example 2: -1.50DC x 25 - 5.50 DS @25 Rx: - 5.50/-1.50x115 - 115 +2.00 (WD, 50cm) ___________________________ -1.50 DC@115 - 7.50/-1.50x115 Final Rx.: LE: - 7.50/-1.50x115, VA: 6/6 Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Retinocopy- the Procedure Most Common Errors Performing retinoscopy at an incorrect working distance. Performing retinoscopy off-axis. Blocking the patient’s view of the distance chart Confusing the retinoscope collar positions (plano-mirror and concave- mirror positions). Not concentrating on the movement in the centre of the pupil in a patient with large pupils. Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Summary Retinoscopy in an objective method to assess refraction Accommodation needs to be controlled during performing the test Two techniques can be used to perform retinoscopy Sph/Sph Sph/Cyl Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Reference & Further Reading Grosvenor’s Primary Care Optometry. Butterworth Heinemann. 5th edition. Eskridge, Amos, and Bartlett’s Clinical Procedures in Optometry. Lippincott Williams & Wilkins. Primary Optometry Care I - Ithar M Beshtawi, Ph.D  Next Topic Subjective Refraction Primary Optometry Care I - Ithar M Beshtawi, Ph.D