Retinoscope and retinoscopy

This presentation explain about retinoscope, the instrument, its history, its types, the procedure and different cases also the advantages and disadvantages of the instrument and the working lens

1. Retinoscopy Loknath Goswami B.Sc Optom 2 nd year Ridley College of Optometry Jorhat, Assam

2. Introduction Retinoscopy is an objective method of measuring the optical power of the eye It is used to illuminate the inside of the eye and to observe the light that is reflected from the retina These reflected rays change as they pass out through the optical components of the eye, and by examining just how these emerging rays change, we determine the refractive power of the eye

3. Evolution of retinoscopy 1859 – Sir William Bowman commented on the peculiar linear fundus reflex he saw when viewing astigmatic eyes with Helmholtz’s new ophthalmoscope 1873 – The first objective diagnosis of refractive errors was by the french ophthalmologist Cuignet (Father of Retinoscopy )

4. 1878 – Mengin published the clear and simple explanation that helped to popularize the retinoscopic technique 1880 – Parent, published his explanation of quantified objective refraction 1903 – Duane first advocated the systematic use of cylindrical lenses for retinoscopy in astigmatism

5. Copeland’s contributions Around 1920, Jack C. Copeland was using one of Wolff’s original European spot retinscopes , when he dropped the instrument on the floor, damaging the bulb filament. When reexamining the schematic eye that he was working with, he noted a difference in the reflexes, and set about solving what had happened. From this original observation came the streak retinoscopic technique that is taught today

6. 1927 – Copeland patented his original model, popularized the streak technique and revolutionized retinoscopy The instrument has five flaws that Copeland corrected in his improved version, marketed since 1968 as Optec 360

7. Advantages Reduces the refraction time and error Minimizes decisions that the patient has to make Extremely important when communication is difficult or impossible - Retarded, deaf persons - Foreigners - Children, infants

8. By evaluating the retinoscopic reflex, we can also detect aberrations of the cornea and of the lens, as well as opacities of the ocular media

9. Types Reflecting mirror retinoscope Plane mirror retinoscope Priestly-Smith’s mirror retinoscope Self illuminated retinoscope Spot retinoscope Streak retinoscope

10. Plane mirror retinoscope

11. Reflecting mirror retinoscope A perforated mirror by which the beam is reflected into the patient’s eye and through a central hole the emergent rays enter the observer’s eye Movements of the illuminated retinal areas are produced by tilting a mirror, either a plane or concave

12. Reflecting mirror retinoscope Advantages Cheaper than the self illuminated Disadvantages Requires a separate light source Glare from that source of light is annoying to the patient To check the axis and amount of cylinder is difficult Intensity and type of beam cannot be changed or controlled

13. Self illuminated retinoscope The light source and the mirror are incorporated in one Streak – light source is a linear (uncoiled) filament Spot – light source is projected round

14. The streak retinoscope The modern retinoscope differs from the simple instrument previously described in two respects It incorporates a concave mirror in addition to the plane mirror The light source is in the form of a streak rather than a spot

15. Parts of retinoscope head

16. Projection system Light source Condensing lens Mirror Focusing sleeve Current source

17. Projection system The projection system is simple; the retinoscope emits rays of light that illuminate the retina (the pigment epithelium and choroid). By turning the sleeve one can rotate the projected streak, and by raising or lowering the sleeve one can make the rays divergent or convergent

18. Observation system Peep hole Mirror The mirror have an optical aperture; the central slivering of the mirror is absent. Some models use a semi-silvered (beam splitter) surface to accomplish the same purpose

19. Handling the retinoscope Hold the retinoscope in the right hand before the right eye, and in the left hand when using the left eye. Keeping both eyes open and the lights low, hold the retinoscope against brow and wiggle head or trunk perpendicular to the streak axis

20. Motions Myopia – against motion is observed Hyperopia – with motion is observed Emmetropia – no motion known as neutral motion or complete flashing

21. Reflex :With movement

22. Reflex :Against movement

23. Neutralized

24. Preliminary steps Set the sleeve in its lowest position ( plano -mirror effect) Position yourself 2/3 meter (26”) from the patient. This distance implies a working lens of +1.50D. The distance can be made to vary. With the refracting equipment in place, direct the patient’s attention to a fixation spot at 15 feet or more from the eye and align the streak vertically

25. Observe the “reflex” which will appear providing no oblique astigmatism is present If oblique astigmatism is present, the reflex does not appear vertical Move the vertical streak horizontally across the pupil and back again and observe whether the reflex moves in the same direction as the streak or in the opposite direction

26. Rotate the control sleeve until the streak is horizontal and move the streak vertically If the streak and the reflex move in the same direction with no lens in the refractive apparatus, refraction is one of these: Hyperopia Emmetropia Myopia of less than 1.50 diopters If the reflex moves in the opposite direction, the error is myopia greater than 1.50 dipoters

27. Determining refractive error by neutralization Before starting, make sure the eye not being refracted has some “against” motion using the plano mirror effect. This will blur vision to prevent accommodation If “with” or neutral motion is noticed initially, place about a +1.00 sphere before the eye once neutral motion is seen

28. Neutralising with spheres only Change sphere in the minus direction until the reflexes in all axes have “with” motion Adjust in the plus direction until the reflex fills the pupil in one meridian and all motion is stopped. This will be one of the principal meridians if astigmatism is present. That meridian is then said to be neutralized Repeat the neutralization in the meridian 90˚ away

29. Confirmation of neutralization Move the sleeve all the way up (concave mirror position); the reflex should also appear neutralized Move closer to the patient and “with” motion should return; move away and “against” motion should appear Place an extra +0.25 sphere in the apparatus and “against” motion should appear

30. Locating the axis of astigmatism Two phenomena help in determining the axis of astigmatism: Break Width Break is observed when the streak is not aligned with a principal meridian astigmatism. The streak will be aligned with a principal meridian when the break effect disappears and the width of the reflex is narrowest ( and it appears its brightest). Then continue with neutralization as before

31. Interpretation of results

32. Hyperopia Hyperopia exists when, at the 2/3 meter distance using the plano mirror effect, “with” motion is neutralized using a plus lens greater than +1.50 diopters and both meridians neutralize with the same strength lens Total hyperopia is estimated by subtracting 1.50 diopters from the total strength lens used. For example, if it takes a +2.50 lens to neutralize motion at 2/3 meter, the total hyperopic error is +1.00 diopter

33. Myopia When “with” motion, using the plano mirror effect at 2/3 meter, is neutralized with a plus lens of less than 1.50 D When at 2/3 meter, using the plano mirror effect, no motion appears at all. The myopia is then exactly 1.50 D When the motion is “against” using the plano mirror effect, and is neutralized with a minus lens

34. Astigmatism Astigmatism exists when the two principal meridians neutralize with different strength lenses. It may be present in many forms: Simple hyperopic Simple myopic Compound hyperopic Compound myopic In the mixed form

35. Astigmatism measurement Neutralize one principal meridian first. Then add the appropriate plus or minus cylindrical lens until the other principal meridian is neutralized Neutralization may also be done by continuing to add spherical lenses until the second principal meridian is neutralized. Then the astigmatic error is equal to the difference in strength of lenses necessary to neutralize the two meridians

36. Axis of astigmatism If the correcting cylinder is of the proper power, a 10˚ error in axis will produce a new astigmatism of approximately one third of the strength of the original astigmatism with its principal meridian at approximately 45˚ to those of the original astigmatism The technique for setting the axis is reffered to as “straddling”

37. Determination of axis When one have an approximate correction of the refractive error and wish to refine the axis setting, the following technique will be helpful. Move up closer to the eye so that the edges of the reflex can be seen Compare the widths of the two reflexes as you rotate the streak 45˚ to either side of the correcting cylinder axis

38. Recede slowly while doing this. Compare the widths of the two reflexes If there is an axis error, the reflex will be of different widths in the two positions When using plus cylinders, one have to rotate the axis toward the narrow band until the reflex widths are equal When using minus cylinders, one have to rotate the axis away from the narrow band When the reflex widths are equal, the proper axis has been determined

39. References John M. Comboy , The retinoscopy book: an introductory manual for eye care professionals 5 th edition, pg no. 1 to 15

40. “ You can’t learn retinoscopy by reading a book. . .” Jack C. Copeland

41. THANK YOU