Get Ready: Visual Field Correction For the Humphrey & Correction and Calibration Goldmann Visual Fields Pitfalls

Goldmann vs. Humphrey

When performing visual fields, When you are doing Goldmann, you must take the you need to “do the math” that patients correction into account. IF you do not, then you will tell you what correction you could be causing refractive scotomas to occur. These need for the test. are areas of non-seeing that are only there because The Humphrey machine will the patient is not visually corrected appropriately. do the calibration for you – but………

A good rule of thumb : any patient not seeing Does the Humphrey know if a patient 20/40 or better should have a refraction prior has had cataract surgery and has an to their HVF/GVF to ensure that you are not IOL or not ?! inducing refractive scotomas. Batman Comics: The Riddler

“To Drop or Not To Drop…That Is The Question !” It all depends on what your doctor is looking for ! No !!!!!!!!! No “right” answer – it is physician preference. The key So…. whether you to doing quality fields is being consistent with the way they are being performed. are doing a IF a patient had a field the last visit dilated, you Goldmann or a would want to do the next field dilated so that you can compare the two. Humphrey, you should be doing the DILATED : largest field possible due to the pupil math. being dilated UNDILATED: the way it is in an every day life

1 Back to Basics Dilated or Undilated ?

When considering what correction to use, it’s Dilated : All patients get a +3.25 added to their sphere the patient’s DISTANCE correction, not their bifocal of their correction regardless of age add that we use ! Undilated: Use the “add for age” chart

added to their sphere Sphere + Cylinder x Axis Astigmatism: Use the astigmatism chart whether they are dilated (+) = farsighted astigmatism where the or undilated (-) = nearsighted astigmatism “lives”

Cylinder Undilated

Cylinder Visual Field Correction

+0.25 none

+0.50,+ 0.75 +0.25 added to sphere

+1.00 or more keep it all

35 y.o. male Undilated Add For Age Table r/o Glaucoma 30 to 40 + 1.00 Glasses Rx: 40 to 45 + 1.50 OD: +2.25 sphere OS: +2.00 sphere 45 to 50 + 2.00 50 to 55 + 2.50 VF Rx: OD: +2.25 sph 55 to 60 + 3.00 +1.00 add for age +3.25 sph 60 and over + 3.25

OS: +2.00 sph This “add” is added to the sphere of the +1.00 add for age Rx. +3.00 sph

2 18 y.o. Undilated 42 y.o. Undilated r/o optic neuritis r/o pituitary tumor

Glasses Rx is: Glasses Rx: OD: +2.50 sphere OD:+1.00 + 0.50 x 92 add +1.25 OS: plano OS:+0.25 + 1.25 x 02 add +1.25

Visual Field Rx: Visual Field Rx: OD: +2.50 sphere OD: +1.00 + 0.50 x 92 OS: +0.25 +1.25 x 02 no add for age..under 30 +1.50 add for age +1.50 add for age +2.50 +2.50 +0.50 x 92 +1.75 + 1.25 x 02 +0.25 for cylinder keep the cylinder ! OS: plano +2.75 sphere +1.75 + 1.25 x 02 no add for age….under 30 no correction

55 y.o. Undilated: Dilated monocular pt with glaucoma Glasses Rx: Do Not Use The Add for Age !!! OD: prosthesis OS: -5.25 +1.00 x 150 VF Rx: Everyone gets +3.25 added to their OD: prosthesis OS: -5.25 +1.00 x 150 sphere regardless of their age ! +3.25 (more than -3.25) Cylinder rules stay in effect for dilated -2.00 + 1.00 x 150 patients !

Dilation Makes Everyone 70 ! What makes you 70 ?!

Because dilation causes patients to lose their ability to see up close IOL (accommodate), we need to give them a +3.25 to help with the test.

What else causes you to Dilating Drops lose your ability to accommodate ? - 3.25 or more Aphakia

3 12 y.o. Dilated : Glasses will give you refractive Sports Screening Exam scotomas ! Rx is: OD: -1.00 +0.75 x 10 OS: plano +1.00 x 10

VF Rx: OD: -1.00 + 0.75 x 10 OS: plano + 1.00 x 10 +3.25 dilated +3.25 dilated +2.25 + 0.75 x 10 +3.25 + 1.00 x 10 +0.25 cylinder ** keep all cylinder +2.50 sp +3.25 + 1.00 x 10

What about contacts ? NOTHING !!!!!!!

Patient’s Rx =

OD: -7.50 + 1.00 x 87 OS: -7.00 + 0.50 x 97

When they wear their contact lenses with the appropriate correction… they see 20/20 OU. Their contacts make them what Rx?

23 y.o. Undilated: Family hx glaucoma & ↑ C/D Glasses RX: Leave the contacts in for the whole OD: SCL 20/15 vision visual field ( either HVF or GVF) ….. OS: SCL 20/15 vision * He wears no other corrective “ Contacts make your nothing ! “ glasses Visual field Rx will be: OD: SCL nothing OS: SCL nothing

4 Correction Holder GVF Correction Holder

Do not use red or black wide rimmed lenses for testing. Same rules… Watch for remove from the fingerprints! machine and place Remove after the the correction in central 30 degrees. the holder. Never use the patients’ glasses 

Anderson: Perimetry

Goldmann Visual Field HVF Correction Holder Calibration Before you can even begin the field, the machine must be calibrated ! This ensures that the light Cylinder is placed intensities are correct and at 45° in this that the machine is standardized. picture. Ideally, the machine should be calibrated before each patient… but in “the real world”, most offices calibrate them once an AM shift and once a PM shift.

Anderson: Perimetry

Calibration Pearls Level The Machine

* 1000 asb (apostilb) On the bottom An apostilb is a unit of luminance = to of each side of 0.3183 candela/m2 or 0.1 millilambert the perimeter, * 32.5 versus “ what it is” there are levels. * lock pantograph handle at 70° Adjust the levels so that the “bubble” Cannot do the visual field if you do not is in the center of calibrate! each circle.

5 Lock Pantograph Arm At 70° Adjust All Levers to V4e

70° is located Located in the on the right upper right hand side of hand side of the paper on the machine. the horizontal Make sure the line. Push levers are in knob in to lock arm. the grooves.

Turn Machine On..Turn Levers Stimulus Light Switch To On Intensity (0.1 log) Located on the right lower side. During calibration, Intensity (0.5 log) “twist” knob to keep light on. After calibration you will push “down” on lever to Size turn light on/off.

Raise The Flag Turn the Room Lights Off!

Located on right hand side of the bowl. Gently push the flag up. DO NOT grab the flag with your fingers because the oils on your fingertips can cause the flag to become discolored.

6 Calibrate The Light Meter

IF all the steps have been If the light meter performed up to this point, does not read 1000, the light meter should read adjust the 1000 asb . There stimulus knob are (2) types of located on the light meter: lower left hand a. will automatically side of the machine. react to the light IF after adjusting it hitting the meter still will not read b. there is a red button behind the meter that 1000, change the you push in the activate the meter bulb !

Lower The Flag

This knob will Lower the flag. adjust the paper Now instead of screen intensity the light hitting so you can see the light meter, we what you are will use the flag drawing. Adjust to calibrate the this to full on before you start the test. bowl.

Go To Right Side Of The Move Levers To V1e Machine- Look Through Slat Move all the levers so that they read V1e.

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Close one eye. With your right arm, reach up and adjust the Adjust black, ribbed light rheostat until housing. Careful – bowl and flag this gets hot fast! If Look in blend you pull on it too hard, here ! it will also come off. It’s ok…put it back on !

The Book vs. Real Life Test vs. Real Life

The book says (and for all written tests the At this point, unlock the answer will be) that when adjusted properly, arm. Put the patient in the the bowl reading is 32.5. But, in the real machine. Re-lock the arm. performing world, when the test, the answer The book states that when is “whatever the light housing reads on the you calibrate the bowl, you scale”. There is a scale imprinted on the need to have the patient in housing, in units of “1”. Read the numbers and record that as your answer during performance there. You want to adjust the bowl intensity tests. in accordance to what they are wearing !

Other Tips Before Starting Other Tips Before Starting

Focus eyepiece Handle down gives a smaller target for by pulling in and the patient to see. This helps prevent out on the tube. micro scanning from side to side of the Adjust patient target. fixation to small (switch down)

8 Theory vs Real Life

Handle up gives a much larger viewing “25° Temporal Rule” ° spot. This can Put the pantograph handle on the 25 spot on the right hand side of the paper. Adjust sometimes cause levers to I2e. Turn light on. If patient difficulties while you responds, this is what you start the test are plotting the blind with. If not, adjust levers to I3e, and spot. continue to increase stimulus size/intensity until patient responds. Start test with first light they respond to.

Why Don’t I Like This ??

IF the patient starts the test with the I4e, do you know if they see the I2e or the I3e ?

One reason to do VF’s is progression. Start with I2e, and go larger. IF after time the patient cannot see the I2e…it is gone. And that is progression ! Don’t start with the largest stimulus and work in !

Kinetic Perimetry Isopter

An isopter is a connection of responses to a given stimulus. Moving from an area You get an isopter by of non-seeing to a performing kinetic presumed area of perimetry. The seeing using a given implication is that size and intensity of everything inside that light to find the circle of lights is seen boundary or by that stimulus. How do threshold of you know ?????? that light.

9 Static Perimetry Take The Plunge – It’ll Be A Blast 

Once you have an isopter, you then need to check inside to see if there are any areas of non- seeing. You are looking for scotomas. You need to check 75-100 times in the central 30 degrees.

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