Retinoscopy:
retinoscope setting: diverging beam ( not pushed down )
fog both eyes to strat off ( both eyes show against movement )
for each eye
{
operation rule:
when with movement is observed: add +ve lens
when against movement is observed: add -ve lens
follow the reflex to determine axis
sphere end point:
neutral in one meridian; against movement in another meridian
add -ve cylindrical lens to neutralize the remaining meridian
}
check VA, expect >6/12
--------------------------------------------------------------------------
Subjective Refraction:
occlude the other eye
initial sphere: ask patient to compare two given lens for certain times to establish initial sphere
duochrome test: on green ( ensure a liitle over-minus to proceed to JCC )
JCC:
{
establish axis:
1. add -0.25 cyl if there is no cyl from retinoscopy
2. JCC arrow not pointing "P"
3. "better 1, beeter 2", allowing sufficient time for comparison
4. turn axis towards red dot accordingly
5. end point: unable to distinguish
determine cyl power:
1. JCC arrow pointing "P"
2. "better 1, beeter 2", allowing sufficient time for comparison
3. acceptance: red dot aligning with axis; rejection: white dot aligning with axis
3.1 acceptance: add -0.25 cyl; rejection: take away -0.25 cyl
3.2 "2:1 ratio": add +0.25 sphere for every additional -0.5 cyl; take away added sphere for regression
4. end point: unable to distinguish
refine axis:
1. JCC arrow not pointing "P"
2. "better 1, beeter 2", allowing sufficient time for comparison
3. turn axis towards red dot accordingly
4. end point: unable to distinguish
}
final sphere & MPMVA: ask patient to compare two given lens for certain times; more +ve lens perferred
+1.00D blur: add +1.00DS, see if patient's VA drops to 6/12 or worse; add -0.25DS repeatedly until best VA
duochrome test: equality or on red ( ensure no over-minus )
