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Accommodative Facility
PURPOSE
To measure the patient’s ability to make rapid and accurate accommodative changes tinder monocular or binocular conditions. Accommodative facility testing is part of a full functional analysis. The findings help to distinguish primary accommodative from primary binocular anomalies.
INDICATIONS
Accommodative facility as described here is done only on nonpresbyopes.
EQUIPMENT
·+2.00/-2.00 lenses mounted in a flipper device or a Lemos Slider (available from Bernell).
·Near target (printed material containing letters one or two lines larger than the patient’s near visual acuity in his poorer seeing eye).
·Eye patch.
·Polaroid glasses.
·Polaroid bar reader.
·Illumination source.
·Timepiece with second hand.
SET-UP
·The patient wears his distance correction. Trial frame it if necessary.
·Have the patient hold the near target at 40 cm in good illumination.
·The patient wears the Polaroid glasses over his habitual correction during the binocular but not the monocular part of this test.
·Place the bar reader over the near target during the binocular but not the monocular part of this test.
STEP-BY-STEP PROCEDURE
1. Make sure that both of the patient’s eyes are unoccluded; and he is wearing the Polaroid glasses.
2. Place the +2.00 lenses in front of the patient’s eyes and ask him to report when the print clears.
3. As soon as the print clears, flip the lenses to their -2.00 position.
4. Repeat steps 1 and 2, noting the number of full cycles that the patient completes in 60 seconds. A full cycle consists of both +2.00 and -2.00 lenses. Throughout steps 1 to 3, keep telling the patient to be certain that he can see all of the letters through all of the bars of the bar reader (see Figure 4-14). If the patient is unable to see through all the bars, he is spressing an eye. Binocular facility testing cannot be done on this patient. Determine which eye is being spressed (see Figure 4-15). Proceed to step 6.
5. If the patient clears 8 or more cycles in 60 seconds, record the actual number of completed cycles. If the patient clears fewer than 8 cycles in one minute, go to step 6.
6. Remove the Polaroid glasses and the bar reader.
7. Patch the patient’s left eye and repeat steps 2 and 3 on his right eye. Note the number of full cycles the patient completes in 60 seconds.
8. Then patch the patient’s right eye and repeat steps 2 and 3 on his left eye. Note the number of full cycles the patient completes in 60 seconds.
RECORDING
·Record the number of cycles completed in 60 seconds for both eyes together and, if applicable, for each eye monocularly.
·If the patient is able to complete fewer than the expected number of cycles per minute (cpm) on any portion of the test, record the actual cpm and indicate whether he had greater difficulty clearing the plus lenses, the minus lenses, or both.
·If spression occurred during the binocular portion of the test, record which eye spressed.
EXAMPLES
·Accom. Fac. OU 4 cpm, slow on plus, cleared minus easily / OD 12 cpm, OS 11 cpm
·Accom. Fac. OU 3 cpm (failed minus) / OD 4 cpm (failed minus), OS 3 cpm (failed minus)
·Accom. Fac. OU spression OD after 1 cycle/OD 8 cpm, OS 7 cpm
EXPECTED FINDINGS
·Children 8-12 years old 5 cpm binocularly, 7 cpm monocularly
·Adults 13-30 years old 8 cmp binocularly, 11 cpm monocularly
·Adults 30-40 years old 9 cpm binocularly
·The monocular findings should be within 4 cpm of one another.
·When both eyes are tested, the second eye can be expected to clear as much as 1 cpm less than the first eye tested. |
