Streak retinoscope

Under optic instrumentation

1. STREAK RETINOSCOPE: Welch Allyn ® Elite™ REF 18245 PREPARED BY: Anis Suzanna Binti Mohamad A 123369

2. OVERVIEW what is streak retinoscope basic principle advantages Disadvantages Conclusion

3. INTRODUCTION Retinoscopy - an objective method of measuring the optical power of the eye. Retinoscope - an instrument that we used to illuminate the inside of the eye, and to observe the light that is reflected from the retina. By examining just how these emerging rays change, we determine the refractive power of the eye.

4. According to the Dictionary of Optometry And Visual Science; 5 th Edition,pg:267, streak retinoscope is a retinoscope which projects into the patient’s eye an oblong streak which can be adjusted in width and rotated in various meridians. There are two types of retinoscope such as: Spot retinoscope Streak retinoscope What is streak retinoscope?

5. The retinoscope how it works “ There’s less in a retinoscope than meets the eye……..” Paul (“Doc”) Berry

6. Basic principle in streak retinoscope There are two systems operating in streak retinoscopy: Projecting system Observation system

7. External part of streak retinoscope

8. 1) Projection system Main purpose : To illuminates the retina Contains the major components such as: Light source Condensing lens Mirror Focusing sleeve Current source

9. Function of each components in Projection system Components in projection system Functions Light source A bulb with linear filament that projects a line of light or streak Condensing lens the lens that responsible for focusing the rays from the bulb onto the mirror Mirror bends the path of the light at right angle to the axis of the handle, therefore the beam projects from the head of the retinoscope Focusing sleeve/ vergence control to project the rays either diverge (plane mirror effect) or converge (concave mirror effect) sleeve changes the focus ( vergence ) by moving bulb up or down Current source Consist of battery in handle (rechargeable/replaceable) Corded handle with connected to the electrical source

10. Figure 2.4 Usual method of vergence control (lens is fixed). Copeland type.

11. Figure 2.5 Alternative method of vergence control (bulb is fixed). Welch Allyn type.

12. Current sources Corded handle Battery handle

13. 2) Observation system Main purpose: To allows the observer to see the retinal reflex of the patient.

14. Light pathway in observation system

15. From observation, the observer can see the characteristics of the moving retinal reflex. The observer can detect refractive errors such as myopia,hyperopia , or astigmatism. The observer can measure the condition by placing lenses in the path of the retinal reflex. When the correcting lens create neutrality, this is the power of the patient’s refractive error.

16. Overall system of the streak retinoscope

17. Advantages of Elite™ Retinoscope Provides 2.8X the brightness of standard retinoscopes Superior streak quality -easy in patients with small pupils Crossed linear polarizing filter eliminates bothersome glare from trial lenses External focusing sleeve Sealed optics keep the lenses cleaner Fits all Welch Allyn 3.5 V power sources

18. Welch Allyn 18245 Streak Retinoscope

19. Disadvantages of Elite™ Retinoscope The transparent sealed optics easily have the finger print. The light too bright Induces pupil constrict The batteries will easily lasting The bulb is bright

20. Conclusion As we have seen, retinoscopy is an essential technique in optometry field as it can be very helpful to the patient such as children, nonliterate, hearing impaired, language disorder, or indecisive. Whatever the brand that observer used not determine the accuracy, the endpoint lies in the observer’s successful performance and interpretation of the art.

21. References: Books John M. Corboy,M.D., David J. Norath, and Richard Reffner. The Retinoscopy Book: An Introductory Manual for Eye Care Professionals. University of Honululu,Hawaii: SLACK Incorperated, 1996. George E. Garcia,M.D. Handbook of Refraction. Boston : Little, Brown and Company. 1989. David B. Henson. Optometric Instrumentation . Oxford: Butterworth Heinemann. 1996. David B. Henson. Optometric Insrumentation . London : Butterworth& Co. (Publishers) Ltd. 1983. Michel Millodot. Dictionary of Optometry And Visual Science. Oxford : Butterworth Heinemann. 2000. Internet sources Welch Allyn Corporation, “ Retinoscope”. 17 Jan. 2010 < http://www.welchallyn.com/wafor/students/Optometry-Students/Retinoscope_2007_05_09.htm>. Welch Allyn Corporation, “ Optometry Student Instruments”. 16 Jan. 2010 <http://www.welchallyn.com/wafor/students/Optometry-Students/default.htm >

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