Do children with amblyopia have binocular cells?

Will alternating strabs be binocular?

-no

-no

-reduced VA with optimal refractive correction

-VA reduced with ND filter

-crowding phenomenon

-distance vs near VA

-accommodation

-refraction

-ocular motility

-eccentric fixation

In addition to reduced VA, what else does an amblyopic eye experience?

Can amblyopic acuity be quantified with the Snellen Chart?

- loss of contrast, abnormal contour interaction, perceptual distortion, and many other changes

-this is very difficult

What are some ways of measuring VA?

What are some disadvantages of Teller Acuity cards

What are some disadvantages of pediatric VA charts?

-OKN drum

-preferential viewing

-Teller acuity cards (grating VA)- may underestimate amblyopia; falsely high VA

-Visual Evoked Potential (VEP)

-Landolt C for older adult children

-Pediatric charts- unequal number of symbols on each line and unequal spacing of images

-Lea Chart

-Psychometric VA (upside down E)

-Electronic Visual Acuity tester (EVAT)

What is the effect of a neutral density filter?

What kind of effect will the ND have on eyes with organic visual loss?

How is the ND used?

What is the strength of the ND filter usually used?

-relative improvement in VA of amblyopic eye in mesopic and scotopic conditions

-profound

-to distinguish between organic vision loss and amblyopia

-2.0-3.0 

What is the procedure for using the ND filter?

What results do you expect in amblyopia?

- patient is adapted to a dimly lit room for 5 min with the ND filter over the unaffected eye and the VA is taken; the filter is then moved to the amblyopic eye and after 5 min the VA is taken

-VA of the amblyopic eye, relative to the better eye will improve or stay the same; with organic visual loss the VA of the affected eye will reduce compared to the normal eye

Which amblyopes are most affected by crowding phenomenon?

What happens to the VA when crowding bars are added in amblyopia?

Is this specific for amblyopes?

What would you expect of the VA with individual optotypes?

Is this phenomenon seen in organic visual loss?

How can this be used clinically?

-strabismic and anisometropic amblyopes

-the visual acuity is reduced

-no, can happen in normal binocular vision

-would be better by ~4 lines

-no- cannot be expected from different methods of measurement

-differentiate between organic and functional vision loss and can be prognostic prior to treatment

What might you expect of the near VA in amblyopia?

What do other studies suggest?

So approximately how many ambylopes have better VA at near?

- may be better (rarely tested)

-that some are better at distance and others are unchanged

-1/3

What did the PEDIG 2011 study reveal about distance and near VA?

What is this inconsistency likley due to?

that there is no significant difference between distance and near VA in amblyopic eyes

-individual differences in test-retest variability

What aspects of accommoation are affected in amblyopia?

How does accommodation in amblyopic eyes compare to normal eyes?

What are the 4 findings concerning accommodation in amblyopic eyes?

Which tests are the best discriminators for accommodative function?

-amplitude, response, facility

-reduced accommodative function

-reduced accommodative amplitude, response, facility, and increased depth of focus

-minus lens amps and dynamic retinoscopy push-up

How does the knowledge of accommodative problems affect prescribing for amblyopic patients?

How much would could you cut?

-might not want to cut too much of the plus from the cycloplegic hyperopic correction

-no more than 1- 1.50D for anisometropes and isoametropes

What did the 2004 study by Rutstein and Corliss show?

What was the purpose of the PEDIG 2011 study?

What did this study show?

How did strabismus affect this?

- myopic shift in amblyopic SA and AA eyes over 9 years and bilateral myopic shift in IA over 9 years

-to determine whether change in RE is due to ocular alignment in children age 3 to >7 treated for amblyopia

-change from hyperopia to less hyperopia by 10 yoa

-children without strabismus in amblyopic eye experienced greater myopic shift than amblyopic strabismic eyes

How is ocular motility affected in the amblyopic eye?

What happens in pursuits of amblyopic eye?

What happens in saccades?

-nystagmus, jerks, flicks in eye movements are exagerated in amblyopic eyes

-not smooth, but jerky and nystagmoid, lag behind demand and do not follow th epath of the target

-may show slowness of response and searching or corrective movement before finally finding the second target

What happens with EF?

Where is fixation usually found under monocular amblyopic conditions?

When does the EF exist?

What happens to the VA the farther away the EF is from the fovea?

What is the incidence of EF in strabismic amblyopes?

Does this usually happen in AA?

-sometimes the amblyopic eye does not use foveal fixation when the non-amblyopic eye is covered

-off-center of the fovea

-only under monocular conditions

-gets worse

-23%- 82% of SA

-no, they usually centrally fixate

Can cover test with prism accurately quantify the deviation in EF with strab?

What are the 3 prerequisites for the cover test?

Is EF usually positive or negative?

What test is used for EF?

What law does this follow?

How will EF affect the cover test?

-no

-good VA, accurate accommodation, pt fixates at the fovea

-can be either

-Krimsky method (BI for XT)

-Hering's law- prism in front of the fixating (normal) eye moves the deviating eye

-will detract from it

How is EF classified?

What are the parameters of each?

-constancy, location, direction

-constantcy or inconstantcy of retinal area used and fixed or variable (more common)

-foveal off-center (1 degree or less); parafoveal (1-3 degrees); paramacular (3-5 degrees); peripheral (>5 degrees)

-direction- nasal, temporal, superior, inferior

-comparision of angle kappa in each eye

-visuoscopy

-Hadinger brushes

-after-images (academic)

What is the angle kappa?

How is this interpreted?

What is a disadvantage to this test?

What is a normal angle kappa?

- the angle between the pupillay and visual axis

-if equal, normal fixation; if unequal, EF

-misses small angles of EF

-positive, or slightly nasal

What is a condition that mimics EF?

What is this due to?

What conditions may cause this?

-ectopic macula

-temporally stretched macula

-ROP, toxocara, retinal folds

What is visuoscopy?

Which eye should be done first?

- ophthalmoscope adapted for testing fixation by inclusion of a small opaque sized target and serves as a fixation point and casts a shadow on the fundus- fovea is used as a reference point

-the non-amblyopic eye

What are the Hadinger brushes related to?

WHat must be normal in order to experience this entoptic phenomenon?

Which eye should be tested first?

-Nerve fiber layer of Henle and the yellow pigmentation in the macular area when stimulated by plane polarized light

-anatomical constituents must be normal in structure and arrangement

-non-amblyopic eye

What is the formula to determine EF with Hadinger Brushes?

What is the test distance used?

- EF (PD) = 100 x sep (cm) / test distance (cm)

-50 cm

After-image transfer is based on what?

What is the assumption of this test?

What formula can be used to determine the amount of EF?

-presumed NRC

-an image falling on the fovea of one eye will be transfered to the fovea of the fellow eye

- EF (PD) = 100 x sep (cm)/ test distance (cm)

Can you predict the EF from the VA?

Can you predict the VA from the EF?

How does this differ for amblyopic eyes for normal eyes?

What is the formula to determine the amblyopes VA?

Is there any advantage to a patient to have eccentric fixation?

-no

-somewhat

-VA decrease for increase in EF does not correspond identically with that or normal eyes with same amount of EF

-EF + 1= MAR

-no

Non-Clinical Features

What are the psychophysical measures?

How do these features compare to amblyopic eyes?

-dark adaptation

-spectral sensitivity

-differential threshold

-contrast sensitivity

-CFF

*high spatial frequencies are reduced for amblyopic eyes

- subjective measures in which the responses of the amblyopic visual system to specific test situations are compared to responses of the normal visual system

-da- similar to normal

-ss- similar to non-amblyopic eye

-dt- slight elevation

-cs- requires higher luminance

-CFF- increased threshold

-VEP- increased latency and reduced amplitude

-ERG- normal (retina)

-EOG- normal