|
Dynamic Retinoscopy: Monocular Estimation Method (MEM)
PURPOSE
To objectively measure the accommodative response to the near working distance. This technique is useful in the diagnosis of binocular anomalies and for predicting the efficacy of some forms of therapeutic intervention.
EQUIPMENT
·Retinoscope.
·MEM retinoscopy card.
·Trial lens set or lens rack.
SET-UP
·The MEM card should be attached to the retinoscope with the beam of the retinoscope passing through the hole in the center of it (see Figure 4-16).
·The test is performed under normal room illumination.
·The patient should wear his habitual near correction.
·The test is performed under binocular viewing conditions.
STEP-BY-STEP PROCEDURE
1. Position yourself so:
a. the MEM card is at the patient’s customary working distance (CWD). When examining children, Harmon's Distance (the distance from the patient’s elbow to his knuckles) is frequently used as an alternative to the CWD.
b. you are on the patient’s midline and the patient’s eyes are slightly depressed, thereby more closely simulating a normal reading posture.
2. The streak of the retinoscope should be oriented vertically and positioned on the bridge of the patient’s nose.
3. Ask the patient to read the letters or words on the card. With children it is often useful to have them do this out loud.
4. While the patient is reading, quickly guide the streak across the patient’s right eye and eva luate the reflex for with, against, or neutral motion. Be sure to observe the reflex in the center of the pil rather than the edge.
5. Estimate the dioptral value required to neutralize the observed motion. (With-plus; Against-minus).
6. Confirm the estimate by quickly (＜1 second) interjecting a lens of the estimated power into the patient’s line of sight while eva luating the reflex. If the estimate is correct, neutrality will be observed.
Note: It is critical that the lens be interjected, the reflex eva luated, and the lens removed quickly. Prolonged exposure to the lens is likely to induce an accommodative response and result in invalid data.
7. Repeat steps 2 through 6 for the left eye.
RECORDING
·Record the technique used (MEM).
·Record the lens power required to attain neutrality for the OD and the OS.
EXAMPLES
·MEM 0D +0.50
OS +0.75
EXPECTED FINDINGS
·+0.50 |
