BVP Flashcards
Heterophoria definition, tests and Fusional reserve compensation
1) Eyes misaligned when one is covered or viewing different objects.
if decompensated then becomes a tropia.
2) CT, Maddox rod (Distance), Maddox wing (near)
3) How much fusion we have in reserve to compensate a heterophoria
Symptoms decompensated heterophoria,
vision problems, binocular problems, asthenopia problems
Sx - symptoms when using for prolonged time period
VISION PROBLEMS
Diplopia (after long periods) , blurred vision
BINOCULAR PROBLEMS
accom difficulties, stereopsis problems, monoc comfort
ASTHENOPIA
headaches -(x heterophoria frontal headaches, y heterophoria occipital headaches)
eye ache -(intense eye use)
soreness,
general irritation -(difficulty in maintaining BSV)
Order of correcting decompensated heterophoria
Sx, CT, Rx, FD, FR, Stereopsis, suppression
Fusional Reserves for heterophoria (Percivals and Sheards)
EXOP - investigate convergence with Base Out
ESOP - investigate convergence with Base In
Percival’s - convergent and divergent should have balanced FR.
Sheards’s - opposing fusional reserve should be twice the degree of phoria. Works well at distance aswel
Fixation Disparity (what is it?)
Both eyes correspond to the same points on the retina. (Panums). This allows eyes to deviate a small amount with BSV. FD is this small deviation.
Too small to detect with CT.
Mallett Unit disparity test for Fixation Disparity
corrected
1) unit held at reading distance and measure
2) px fixate on OXO
3) ask if strips in straight line
4) visor on and ask if strips still seen
5) if no, suppression, stop and record
if flashing, intermittent suppression.
both seen, proceed
6) px read 2-3 lines of text surrounding
7) ask if strips aligned. top strip LE, bottom strip RE. FLASHCARD 4
8) add min prism to realign markers (associated phoria).
Greater prism, worse sx
FD suggests decom heterophoria
if no sx, no need for treatment,
For others, can have prism in specs
Suppression Test - Mallett Unit
if BV understress, small parts of central field of one eye is inhibited by mismatched images. Compensatory mechanism to keep BSV.
Visor on and corrected, unit at 35cm
1) read letters from top to lowest line, record
2) occlude LE, some letters may change, record polarised letters seen by RE
3) swap eyes
4) abnormal if read one line further monocularly
Vertical heterophoria
VFR small, as little as 1D can be decomp
Order of correction for phoria
Remove cause of decompensation Refractive correction Orthoptic exercises Prescribe prism relief Refer to another practitioner
Removing cause of phoria
Less near screen work
Better illumination and contrast
EXOP, ESOP, -ve, +ve, Quantity of refractive correction?
Review time?
ESOP
+ve) Full plus, relax accom
-ve) Avoid over correction
EXOP
+ve) least plus (partial)
-ve) Min overcorrection which compensates
Review every 3- 4 months
Orthoptic exercises, who for?, what is it for? what information to give when prescribing
If rx doesnt fix sx, 12-35, px motivated
1) Develop FR and relative accom
2) train accom and convergence
3) develop appreciation of physiological diplopia
4) treatment of suppression
written instruction, 15 mins everyday, px must relax eyes after by looking far for 10 mins, monitored 3/4 weeks, sx may worsen initially
Prism relief for heterophoria and adaptation
EXOP - BASE IN
ESOP - BASE OUT
May adapt 2-3 mins and heterophoria return to normal
Where does the weakness lie for EXO and ESO Phoria?, how to manage?
EXOP -
Convergence weakness -
(Convergence FR development, increase BOUT, maintain BSV at near,
Develop negative relative accom, +ve sph, maintain BSV
Appreciation, jump and negative fixation)
Divergence XS -
Same as convergence weakness
ESOP -
Convergence XS -
(Divergence FR development, inc BIN maintain BSV at Near,
Development of positive relative accom, -ve spheres while BSV)
Divergence weakness - (when + corrected, compensation, appreciative exercises)
Exercises to develop FR and relative accom.
1) Dissociated methods - polarized vectogram and anaglyph techniques
2) free space non dissociated methods
3) prisms in free space
4) lenses in free space
5) pencil to nose
6) near/far jump exercises
Dissociated method - Polarized vectogram and anaglyph techniques
TECHNIQUE
1)cross polarized/anaglyph filters
2)2 identical slides given, except 1 red, 1 green
3)
CONVERGENCE TRAINING - move green to left and red to right
DIVERGENCE TRAINING - move green to right and red slide to left
Free space non dissociated methods
3 cats -card with 2 similar cats but differing characteristics, 33cm
EXO
1) card near, px holds pencil in between and fixates on it, px must fuse images together
2) exercises relative negative accom
ESO
1) card near and transparent, px fixates distance and above, must fuse images together
2) exercises positive relative accom
Prisms in free space
C AND D FR
1) practitioner increases BOUT prism, px maintain BSV at N. For decompensated exophoria
2) if fusion breaks, px regain BSV
3) if unable to, prism reduced until able to
BIN for eso
Lenses in free space
+ve relative accom: ESO
1-px view small letters 40cm away
2-lenses added in -0.25 increments until blurry
3-encourage px to make single again, 1try to increase -
-ve relative accom: EXO
1-same but +ve lenses
Pencil to nose
pencil 50cm away, maintain BSV as brought close.
Repeat to bring convergence closer
Jump exercises
Ensure px can see targets clear
Fixation jumps between D and N
Physiological diplopia appreciation
pencil(N) in front of picture(D).
When px focussed N, picture is double
When px focussed D, pencil is double
Exercises to develop NPC
and other benefit
DOT CARD
BROCK STRING
can develop physiological diplopia
Treatment of suppression - exercises
Usually when correcting heterophoria, suppression is treated
If not:
Bar reading
1)pencil between eyes and book, used to occlude part of the text
2)if suppression, they have to move head to be able to read
3)px should be encouraged to use suppressing eye.
Vertical septims, vertical prisms and anaglyphs
What is vision screening? and why do it?
Identifiying healthy people that may be at risk to a disease or condition.
Information given from tests, how we can act to reduce risks.
Reduce risks of?
Amblyopia - one of leading causes
high rx - high myopia may indicate associated or systemic disorder
strabismus - infantile/accommodative SOT
stereopsis - usually conjunction with amblyopia
CV - ishihara test
Community screening, what ages
- Screening of all infants in 1st yr of life. After 6-8 weeks (neonatal, red reflex)
- <4yrs, unreliable
- Between 4 and 5 yrs is the best time (sure start programme)
- school entry - some form of assessment
- 8 to teens - diversity
- children with special needs
- Health of all children - hall report
Community screening tests
- new born and 6-8 months- red reflex, corneal light reflex, inspection of eyes
- VA - Power refractor
- City Vision screener for school
City vision screener
245 children, 5-8yrs
Defect found in 19.6% - not including colour def
2/3 unaware of problem
47.3% never had an eye test
Impacts and Consequences of vision screening
- Q of disability caused by RX unknown
- Blurred vision affects child’s progress
- affects academic and sporting ability
- CV issues may cause difficulty with colour coded materials
- some defects prevent individuals entering certain professions
What is convergence?
- Coordination and simultaneous inward movement of the eyes.
- Does not happen in isolation.
- Accom essential for Binocular Visual acuity
What is accommodation?
- Ability of eye to focus dioptric power to obtain a clear image.
- Does not happen in full isolation
- essential for BV at near
Convergence insufficiency and cause and sx. order of correction
- Inability to produce comfortable NBVA
- Can result from another BV anomaly
–>cause
primary - illness, fatigue, drugs, antidepressants, pregnancy
secondary - heterophoria, presbyopia, uncorrected rx, accommodative insufficiency.
–>sx - headaches, eyestrain, sore eyes
treat pathology, rx, cyclopleg, exercies,
Test for convergence insufficiency, and exercises
NPC - target positioned medially from 50cm, RAF rule. cm until double vision
- ideally 5 to 10cm
- assess 3 times, to make sure its not for fatigue
tO IMPROVE
Jump 50 to 15cm, repeat 4 to 5x
Pencil to nose
to train accom use a target w fine detail
CT, FR, VA, STEREOACUITY, OCULAR MOTILITY
Convergence insufficiency vs convergence weakness/exophoria
- decompensated exophoria does not deduce convergence
Convergence paralysis, cause, sx, signs
- Ability to converge to infinity lost
- cause - closed head injury, viral illness, MS, encephalitis
- sx - diplopia, blurred vision at distance closer than infinity
- signs - XOT closer than infinity, reduced accom, absence of pupillary response.
Accommodative insufficiency, cause, sx
-Inability to maintain adequate accommodation for comfortable NBVA
-half of cases with AI have CI
sx - blurred vision at near, asthenopia, micropsia
Accommodative Fatigue, what is it, cause, sx
-Inability to sustain adequate accom over time. Due to repeated to sustained visual effort.
- causes - poor general health, fatigue, drugs
- sx - near vision normal then reduces over time.
Accommodative Infacility, what is it, cause, sx
Inability to adequately change accom
Difficulty in relaxing and exerting accom
cause - accommodative spasm, uncorrected hyperopia, presbyopia, excessive close work
sx - blurred vision, when changing fixation from Near to D. reduced visions.
Accommodative paralysis
The ability to accom, to near objects is entirely gone. No accom can be exerted
may be assoc with convergence paralysis
causes - convergence paralysis, neurological 3CN palsy, trauma
Sx - blurred vision for distance closer than infinity
Convergence/Accommodation spasm, what is it, the muscles affected, causes, sx
convergence spasm usually causes accommodative spasm
Convergence spasm - MR becomes contracted
Accommodation spasm - CM becomes contracted
causes - uncorrected hyperopia, intermittent XOT, drugs/alcohol and inflam
sx - blurred vision, intermittent diplopia, headahe, asthenopia
Test for diagnosis of accom anomalies
Near point of Accommodation
- amp of accom - midpoint between blur and clear, repeat 3 times (to diff if it fatigue) . monoc an binoc.
compare to the norm for the age
-accom facility (rate of accom)
+-2.00D flippers at 40cm. ask px to keep word clear and keep flipping when clear. repeat for 1 min binoc and monoc.
measure cycles per min, one cycle is plus and negative/
average is 7.7cpm
- accommodative lag - objective test. Useful in young patients. 2 methods.
1)accommodative lag: MEM.
px focus on detail placed on ret and kept clear.
ret carried out on x with hand held lenses. held for less than 0.5 secs, avoids distrupting accom.
typical lag +0.75.
more plus - under accom, excessing accom lag.
plano or negative - accom excess. reduced lag.
2)accommodative lag: Nott. distance rx in place, focus on near target 20cm. next to ret. reflex if accommodating accurately under accom - a with move ret closer over accom - an against move ret away 0.75 each way is normal
Dyslexia, cause, diagnosis, signs and sx, perception
unknown cause
diagnosis by psych
signs - closing and covering 1 eye, excessive blinking
sx - headache, eye ache
perception - move n float, blur, wobbly print
Visual factors which correlate with dyslexia, testing, improving, pattern glare
converg, accom anomalies
assoc and decomp heterophoria
binoc instability, - despite heterophoria correction (percivals and sheards), they still have poor binoc coordination.
Due to low FR, Mwing or Mrod used to test
Use vectogram and anaglyph, 3 cats, prism in free space to improve
pattern glare - sx when experiencing repetitive patterns, colours can reduce it. If so, Maeres-irlen syndrome
Visual stress in dyslexia and colorimetry
distortions, washed out colour, visual discomfort, sensitive to light
dyslexic people more likely to suffer from it. Not all do.
PTL and intuitive colorimetry
-Hue, saturation and brightness changed independently
-start with 0- S, increase from 0 to 30 then wait and drop to 0.
-repeat with another hue
when best hue found, use attenuators to check best brightness
-can combine tints for best colour
-lenses tried out under different lighting and refined
-then spec tint
What is amblyopia? Types, when does it develop
1) one eye
Decrease in best VA, not due to any pathology or structural abnormality. Refractive correction does not overcome.
Impediment/disturbance in vision
2)
- Anisometropic - refractive error - one eye receives better input
- Meridonal - astigmatic - blurred on one axis. Monoc - anisometropic. Binoc - ametropic
- Deprivation - Disease - not enough adequate light entering eye (eg, ptosis/cataract). If binoc, congenital
- Strabismic - strabismus, monoc, likely to have ESOT
3) Neural circuitry malleable in critical period due to visual input. At this point in time treatment is more effective. 2- 3 yrs and decreases until 8 yrs
Treating Amblyopia, pros and cons,
Pros
- Better VA in this eye
- if good eye damaged, then backup available
Cons
- BVA already good
- may develop abnormal BV
- may not work
Investigation of amblyopia and explained. how to test
1) HS, VA, CT, stereopsis, refraction, amp of accom, ophthalmoscopy and suppression
2) Crowded Keeler logMAR designed for amblyopia.
Amblyopic eye measured first. If single letters, present in box to induce crowding.
4-5 yrs -
Crowded 0.087 - 6/7.5
Uncrowded -0.010 - 6/6
3) If strabismus - note whether alternating/unilateral. constant/intermittent
4) stereopsis - normal 50 degrees, children w amblyopia >70deg
5) reduced amplitude of accom and amblyopia assoc w abnormal accom
6) in ophthalmoscopy, eccentric fixation should be tested
EF - another point on retina used for fixation. Usually like this if strabismic amblyopia. EF reduces VA
7)Suppression
Sbiza bar.
- graded red filter w increasing density held over normal eye. patient asked what colour light is seen.
- continued until two lights or white light reported
- measures likelihood of diplopia, greater density then lower chance.
- useful after occlusion treatment
Eccentric Fixation, process
1)project ophthalmoscope target on normal retina
2) eye not being tested is occluded
3) px look at centre of target
4) look at centre of the part of the fundus shown
5) swap eyes and see if the same location is shown
if diff part, eccentric fixation occurring.
severity - further from centre, worse it is
Carry out on all strabismics, can be used to measure progression over time
Dilated and cycloplegia to make easier.
Amblyopia, steps for management, factors to consider
1) cycloplegic RX, no hidden RX
2) fundus exam to reveal pathology
3) confirm presence of amblyogenic factors (strabis, anisometropia)
type - worse prognosis for strabismus, mixed
age - older less likely
age of onset - if recent, likely to be able to restore more
acuity - if worse than 6/36, unlikely to respond to treatment
how motivated they are
Refractive correction for amblyopia, occlusion therapy, MOTAS
- 18 weeks to adjust to specs before occlusion therapy and allow VA to plateau
- good eye occluded: frosted lenses, adhesive patches, opaque CL
2 hrs patching (6/9-6/12) -
6 hrs patching (6/24) -
6- 12week monitoring, more reg in children
stop when no VA improvement in 2 weeks
follow up for a yr to prevent relapse
Dose monitors, measure how long patch has been worn for. 120 hrs, 0.1 improv on LOGMAR
Penalization, what is it, types and fogging method
- Blurs good eye enough to make the other work.
- alternative method for those who cant tolerate
- done w specs and enhanced by cycloplegic
Near penalization
- 0.5-1% atropine or cyclopentolate in normal eye
- improvement best with +3.00 over correction.
- Non-amblyopic eye will be used at distance
- Amblyopic eye wilt +3.00D will be used at near
Distance penalization
- blur normal eye with +3.00
- amblyopic eye needs full correction
- clear distance vision in amblyopic eye
- clear near vision in normal eye
Total penalization
- amblyopic eye at all distances
- optimum correction to normal eye
- strong convex lens in good eye to blur all distances
Atropine advantages and disadvantages
Advantages -
cosmetically good
as good as occlusion
useful when px refuses patch
Disadvantages - allergy not useful when severe not suitable for older presbyopes not used when heart defects
Other methods for treating amblyopia
1) Dichoptic training - different and independent
- target for each eye. Tasks require both inputs
- amblyopic eye - higher contrast, to overcome
- suppression and. As progress, contrast is reduced
- until eyes match.
2) Strabismic amblyopia
- full time specs wear for 4 weeks, only give full correction if partial not accepted
- then occlusion
- if eccentric fixation, occlude amblyopic eye for 2 weeks constantly then switch to normal eye. (promoted foveal stimulation)
- warn about intractable diplopia
3) Anisometropic amblyopia
- Full rx 4 weeks for young, partial for older
- refraction, fundus, cl for high rx and anisometropia
- when no improv, occlusion 2 hrs. For poor VA increase time
What is accommodative Esotropia, how, ft, management
intermittent accommodative primary esotropia
DUE TO:
uncorrected hyperopia or a high accommodation convergence/ accommodative ratio or a combination
1) FULLY ACCOMMODATIVE
Accommodative exerted to overcome hyperopia
F/T
- 2-5 yrs, uncorrected hyperopia, child may lose interest in near activities, noticeable when tired, untreated then strabismus
Management
- full Rx and full time, cycloplegic refraction
- Orthopic exercises - (up to +1DC, +3DS, <25D)
- diplopia recognition,
- control of eso (fusion),
- improvement in BVA - via negative fusional reserves with -sph
- Surgery - if decomp still w specs, rx surgery for hyperopia and for those who cant tolerate (adults)
2) CONVERGENCE XS
-occurs at near fixation despite correction,
due to excessive accommodative convergence
-F/T - 2-5yrs, AC/A ratio of 6:1, uncorrected rx, noticed when tired,
non accommodative near target doesn’t deviate
Management - Rx full correction, cycloplegic refraction.
- surgery - >20D and 8:1> AC/A, after 6 yrs
- Bifocals - reduce need to accommodate, decreasing accom convergence.
Min reading add to maintain BSV, month follow up,
- increase add if req,
- if no control then discard.
- If good, then progressively decrease until none
- Orthopic ex NOT FOR:
AC/A >6:1, dev constant at near, exceeds 20D
Use for small dev and same methods
