Lecture 6 Flashcards
Purpose of NRA/PRA
To measure fusional convergence and divergence. Also looks at accommodation.
Normal NRA and PRA values
NRA +2.00
PRA -2.37
Harmon distance
Comfortable reading distance from middle knuckle to elbow.
Lag means you are focusing ___ the target
Lead means you are focusing ___ the target
Lag: behind
Lead: in front
FCC purpose
To determine the lab of accommodation or add subjectively
Near ret purpose
To determine the need for a near vision correction/add over the distance rx.
Ojective info on accommodation done binocularly.
Ex: MEM, NOTT
Benefit to using spot ret
Allows for more light to enter retina. Better color, brightness, observe 2 meridians at the same time
MEM is objective correlate to
FCC
MEM
- Distance?
- Tell patient to do what?
- What does Dr do?
- Expect what?
- Concerns:
- At harmons distance/16 inches
- Tell patient to read cards with both eyes open, wearing appropriate rx
- Dr estimates Diopter value of motion.
- Expect +0.25 to +0.75
- Unequal reflexes, lag reader than +0.75 or against motion, indicating that we need to add minus.
Bell retinoscopy procedure
Pt wears appropriate rx.
Start with target and retinoscope at 50 cm. Keep ret still and move the target closer (wolff wand) and then further away from patient.
No lenses added!
Bell ret. See with motion. Do what?
With motion = add plus. Move closer to make neutral.
Bell ret. See against motion. Do what?
Against motion = add minus. Move further away to make neutral.
How to determine lag doing bell ret?
Compare accommodation response to accommodation stimulus.
The response is the distance the ret is from the patient (50cm, -2.00D)
The stimulus is the distance the target is from the patient when it is neutral. This changes.
The difference between the AR and AS is the lag.
Normal values for bell ret
Lag of +0.25 to +0.75
~16 inches, 40 cm. -2.50
Ret at 50 cm, -2.00
Book ret procedure
While patient reads with appropriate rx, observe the reflex in each eye.
Look at motion, color, brightness and symmetry.
Start with easy material (2 grade levels below) then more difficult.
During book ret, how does the color of the reflex change as the reading difficulty increases?
White –> pink –> Red as difficulty increases
During book ret, how does the brightness of the reflex change as the reading difficulty increases?
Bright –> Dull as difficulty increases
During book ret, how does the direction of the reflex change as the reading difficulty increases?
Low with motion (low plus) to large with motion (high plus)
Nott procedure
Can do this in phoropter
Patient wears appropriate RX
place near card at 40 cm
The examiner moves the RET closer or father until neutrality is reached.
Difference between bell ret and nott
Bell ret: Move wolff wand target. Keep ret in same place.
Nott: Move ret. Keep target in the same place.
In both cases, there are no changes in lenses! Take difference between stimulus of ret and stimulus of target to find lag.
Nott. Notice with movement, what does this mean?
Means you (and the ret) need to move further away from the target. The pt has a lag.
Nott. Notice against movement. What does that mean?
Means you and the ret need to move closer to the patient (in between patient and target) The patient has a lead.
Relationship between accommodative stimulus (moving target) and response (ret)
Non linear. As the stimulus increases, the response can’t keep up.
Stress point
As the target moves toward a patient, they react the stress of the near target with a physiologic response= change in brightness. A quick dull, then re-brightness.
Stress point procedure
Ret held at 50cm. Have the patient look at a target that you move closer to them. Look for a change in reflex BRIGHTNESS, not motion. Brightness will quickly dull then re-brighten.
Stress point. What happens if you give the patient plus lenses?
The plus lenses shift the stress point closer to the patient. They can fixate on nearer targets without stress.
Expected stress point for children and adults
Children: 4 inches closer than harmon distance
Adults: 6 inches from face
What does it mean if you have a high lag
- Eso
- Over minused
- Esos want plus so they can relax accommodation. Will have a higher NRA than PRAq
What does it mean if you have a low lag/lead
- Exo
- Over plused
“just look” technique
Compare both eyes, stability of reflex, what happens when you move target?
Neutralization is not part of the technique.
Color development- what colors can children see first?
Black and white
Infant: red from white
1 month: Blue/green from gray
3 months: Yellow/blue/green from gray
If you are testing color vision for congenital defects, can you do mono or bino?
Ok to test OU
HRR test
-Benefits
Allows you to quantify defect
- Protan/deutan Mild, medium, strong
- Tritan medium or strong
HRR. What happens if the child misses any of the 6 screening plates?
Do entire book. and fill out page based on what child says.
Ishihara color vision test
Has numbers. Plates determines red/green defect. Last plates can differentiate proton from deutan.
Tells if they are strong or mild.
D-15 test
Requires child to figure out the pattern of similar colors. Harder test.
Determines protan from deutan from tritan.
Will have child order them and then you will order them in the circle. Based on the pattern, you can determine their color vision defect.
Computer color vision benefits
Can motor changes over time.
Tests to look at how cones are operating by wavelength.
Pupil testing on infants
Infants have mitotic, sluggish pupils.
VF testing on infants/toddler, preschoolers and school age
Infants/toddler: Have them fixate on central target. Bring target from the periphery, child shoaled observe it. Make sure the peripheral target is non-auditory or you won’t know if they responded to the visual or sound cues.
Preschooler: Count fingers
School age: Count fingers, add
When to do automated visual field on children?
__
What class of drug has a risk of increasing IOP
Steroids
IOP gold standard
Goldmann
Anterior seg assesments
- Slit lamp. Have child sit in parent’s lap or use portable.
- Direct opthalmoscope to look at cornea, sclera, iris.
- Shadow test for open angle
- IOP
Neuro assessments
Color vision, stereo, pupils, cover test.
3 types of anesthetics and what are their uses
Proparacaine, tetracaine, benoxinate
Used to increase absorption of subsequent drops- softens cornea.
If pt is allergic to a “-cain”, what anesthetic drop should you use
Benoxinate
Side effects of anesthetics
Irregular heart beat, dizzy, shortness of breath, nausea, lid swelling.
Cyclo percentages for infants and 1 year +
infants- 0.5%
1 year- 1%
Adverse side effects for cyclo
*Drowsy
*seizure
Ataxia- mimics being drunk
Restlessness
Hallucinations
Hypersensitivity in down syndrome
When to use atropine 1%
Prob uveitis.
Atropine side effects
Sympathetic like side effects
Tachy, dry mouth, flushing, confusion
Hot as a hare, mad as a hatter, red as a beat, dry as a b one.
What class of drugs in is phenylephrine
Alpha 1 agonist- causes vasoconstriction and mydriasis.
Side effects: tachycardia, Bp changes
Length;
Atropine
Cyclo
Tropicamide
Atropine- weeks
Cyclo- 1 day
Tropicamide- 4 to 6
