Refraction Tips

Front 1

Initially put up an entire screen and letters with the 2020 line at the bottom. Ask the patient to read the lowest line on the chart. Now Isolate the line letters just above the line of the patient had little trouble reading. An exception to this would be with the patient who can initially rate 2020. I would keep the patient on the 2030 or 2025 line for the first checks of the sphere and cylinder power and the initial axis check.

Back 1

If a patient is death, I touch system can be used. For instants, you can touch his left hand for one choice in the right or the other. The patient that indicates his preference by moving the appropriate hand

Front 2

Standard order of testing is as follows

Back 2

Severe power check cylinder axis check cylinder power check sphere power refinement

Front 3

On the initial sphere check present the patient with the choice of powers at least a half diopter apart. It's difficult for most people to discriminate between a .25 diopter change.

Back 3

If the initial vision check was not good like 2050 or 2080 you might use .75 diopter changes

Front 4

Cross cylinder axis refinement. Just as you did when checking this year power, have the patient you a line of letters that can be read but is one line above the line the patient has trouble reading. Don't go below the 20/30 line.

Back 4

Binocular balance when finished

Front 5

Never indicate unequal at powers except a young person who has a IOL in one eye

Back 5

You must measure the add powers monocularly because he has one Eye that can not accommodate and the fellow either still has significant accommodate availability. The capital Eye with the IOL add measures to be a +2.25 and the left I add measures to be a +1.25 it would be nice to put a note on the prescription so the optician knows what is going on

Front 6

Given the same situation as described in the prior card if the patient is older and the add powers are closer together perhaps a +2.00 and +250 usually works to fudge a little and give a +2.25 add OU

Back 6

Refraction rule, do not indicate and add power greater than +2.50 unless the best corrected vision is less than 2025 or unless there is a reason why the patient wants to view material closer than the normal reading distance of 16 inches

Front 7

If in and power greater than +2.50 is indicated, then the Nearpoint will be closer than the normal reading distance of 16 inches. For example an add power of +3.25. Will place the Nearpoint at the most, 12 inches.

Back 7

For example we want to know how close a patient with a +4.00 add will have to hold his reading material

F(m)=1/D insert 4 for D

F(m)=1/4 convert to decimal

F(m)=.25 meter (or 25 centimeters)

Front 8

The javal rule is

For keratometer readings of less than 1.7 5D of astigmatism the glasses RX will probably need about .2 5D less correction if you stigmatism is with the rule (90) axis

2. For against the rule astigmatism (180) of less than 2.5 D as measured by the keratometer the glasses RX will probably need .75 more correction

3. When K readings reveal astigmatism greater than 2.5 that D, both with the rule and against a real types need greater correction

Back 8

Done

Front 9

Duo chrome red subtract .25 sph green add .25 sph

The red green test occlude one patient is a 20/40 line asked the patient what letters looks darker and sharper, the letters in the green or the letters in the red. If the patient answer green then .2 5D sphere power is added the procedure is repeated until the letters look equally dark and sharp in the red and the green. Some preferred to keep the patient barely in the green so that the patient has a small amount of accommodative control

Back 9

White light is focused on the retina, greenlight shorter wavelength will focus in front of the retina and red light longer wavelength of focus behind the retina. If there is too much plus correction then the red light will fall on the retina and appear to be in focus while greenlight will appear to be out of focus. If it's too much minus correction the greenlight will be in focus on the retina and red light will be out of focus.