Introduction to Retinoscopy.pdf

Introduction to Retinoscopy Ariette Acevedo, O.D. PPO 1 Retinoscopy • Static retinoscopy is an objective technique used to determine the patients refractive error at distance. • Retinoscopy brings the patient’s far point to the plane of the retinoscope, through the use of lenses. • Working Di...

Introduction to Retinoscopy Ariette Acevedo, O.D. PPO 1 Retinoscopy • Static retinoscopy is an objective technique used to determine the patients refractive error at distance. • Retinoscopy brings the patient’s far point to the plane of the retinoscope, through the use of lenses. • Working Distance: where the retinoscope is located  Measured in cm then transposed into diopters  Important to maintain the working distance steady while performing retinoscopy  While learning, you may use a measuring cord or tape measurer Retinoscopy • Provides an objective measurement  Objective refraction/retinoscopy • It is used as the starting point for subjective refraction  Process used to refine the patients final spectacle prescription, using patient input. • If the patient is unable to respond, retinoscopy is then used as a final prescription. Retinoscope • Most commonly used:  Welch-Allyn  Keeler  Heine Retinoscope Parts • Parts:  Optical head  Sleeve  Battery handle Retinoscope • The optical head projects a slit beam of light called a “streak” from one side of the head. • On the opposite side there is a peephole where the practitioner observes for the retinal reflex movement. • The sleeve allows the streak of light to be changed into a converging or diverging position.  Achieved by either moving the sleeve up or down. • The sleeve can also be used to rotate the orientation of the streak. Retinoscope • Light from the filament passes through the lens to the mirror, where it is reflected toward the patient. • The examiner views the retinal reflex through the aperture behind the mirror. Retinoscope • The Welch-Allyn, Heine and Keeler retinoscopes use a fixed bulb system.  As the sleeve moves up, it creates a concave mirror effect.  As the sleeve moves down, it produces a plano mirror effect.  These retinoscopes are used with the sleeve down. Retinoscope • The plano mirror position projects a light that appears as a diffuse streak when directed at the patients face or your hand. • The concave mirror position projects a more defined streak of light. • By rotating the sleeve the light streak may be rotated in order to project it at any axis. Plano Mirror Concave Mirror 360 degrees Meridians • In retinoscopy the meridian is the line along which you move the streak of light (not the position streak).  Meridian does NOT mean axis • Ex: if the streak is in a horizontal position moving in a vertical manner you are at the 090 axis. • The principal meridians correspond to the orientations of the streak that provide the thickest and thinnest reflexes or the brightest and dimmest reflexes. • Depending on the refractive error the reflexes are going to vary:  Spherical error: same thickness reflex in all meridians  Astigmatic error: thickness will vary in different meridians Meridians • Evaluating the 180 degree meridian  The light is oriented with the 090 degree line, but the streak is being moved along the 180 degree meridian. • Evaluating the 090 degree meridian  The light streak is oriented with the 180 degree line, but the streak is being moved along the 090 degree meridian. Locating the Principal Meridians • Break phenomenon  Light streak and retinal reflex must be in the same position.  Can be used to determine the principal meridians in an astigmatic eye. • Skew phenomenon  The streak moves in one direction and the retinal reflex does not move in the same meridian. Thickness Phenomenon Break Phenomenon Aligned Reflex Break Reflex: rotate the light streak to make both parallel. Skew Phenomenon Retinoscopy Reflex: Motion • 3 types of motions:  With: the light streak and the retinal reflex move in the same direction.  Against: the light streak and the retinal reflex move in an opposite direction.  Neutral: no difference is seen between the light reflex and the retinal reflex. Retinoscopy Reflex: Motion • https://www.youtube.com/watch?v =kAreDffuVCQ With Motion • Reflex moves across the pupil in the same direction as the streak of light of the retinoscope. • The far point is located behind the examiner or the patient’s eye. • Neutralize by adding plus lenses. Against Motion • Reflex moves in the opposite direction of the streak of light of the retinoscope. • Light has focused at a far point that is before the examiner’s and the streak is inverted. • Neutralized by adding minus lenses. Neutral Motion • The pupil lights up and remains constant as the streak of light of the retinoscope moves across the pupil. • The far point is at the examiner’s eye. https://aao-resourcesenformehosting.s3.amazonaws.com/resources/Pedia trics_Center/Retinoscopy-Simulator/ret.html The closer to neutrality the faster, brighter and wider the reflex becomes. http://www.youtube.com/watch ?v=D7_0JNvC1bI&feature=pla yer_detailpage Reflexes • When the far point is dioptrically distanced from the examiner’s eye, the streak is:  Slow  Dull  Narrow • The closer the far point is to the examiner, the streak becomes  Faster  Brighter  Wider Skiaoscopy (Bar) Retinoscopy Equipment • Streak retinoscope • Lens rack or retinoscopy bars, loose trial lenses, or a phoropter. • Fixation target at distance 20/400 with R/G filter • Room lights off • Neutralize movements of the principal meridians  Gross retinoscopy • Using the working distance find the net retinoscopy  Measure your working distance and remove it from the gross retinoscopy Procedure • Identify the meridian with the most WITH motion (thicker reflex)  This is the most plus meridian. • Neutralize this meridian first  Add plus lenses to neutralize the WITH motion and add minus lenses to neutralize AGAINST motion. • Once the most plus meridian is neutralized, move the retinoscope streak 90 degrees away.  AGAINST motion should be seen if the patient is astigmatic.  If neutral motion is seen, the patient has a spherical refractive error.  If WITH motion is seen, go ahead and neutralize this meridian with plus lenses, once neutralized, return to the previous meridian, now it should be against.  Neutralize this meridian • Once both meridians have been neutralized this is the Gross Retinoscopy. Procedure • While using loose lenses or skiaoscopy bars, an optical cross has to be used.  First neutralize the most with motion, then scope 90 degrees away.  Once both meridians have been neutralized, do an optical cross and subtract the WD. • Working distance:  If working at 67cm remove 1.50D  If working at 50cm remove 2.00D • Record findings in minus sphero-cylinder form. Example • Using a WD of 50cm (2.00D) • WITH motion was neutralized with +3.00 while streaking the 180 meridian. • After rotating the sleeve 90 degrees away, against motion was seen and neutralized with +2.00. • What is the gross and net retinoscopy? +2.00 Gross Retinoscopy: +3.00-1.00x180 180 +3.00 090 Net Retinoscopy: +1.00-1.00x180