O3A 2 Deviations

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O3A 2 Deviations
2013-06-26 05:18:10

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  1. What is a deviation?
    when two eyes do not point at the same object of regard- image doesnt fall on both fovea
  2. Whats is a manifest deviation?
    • It is there all the time
    • TROPIA
    • heterotropia, strabismus, squint
  3. What is a latent deviation?
    • only there when you cover the eye
    • brought about by eliminating all stimuli to fusion
  4. What is the stimulus for motor fusion?
    retinal disparity
  5. What is the stimulus for accomodation?
  6. What is tonic vergence?
    • anatomical position of rest
    • eyes tend to diverge after death
    • whilst alive tend to turn inwards- due to surrounding tissue and tone of muscle
    • physical position of rest
  7. what is fusional/disparity vergence?
    convergence compensating for any excess or deficit in tonic convergence stimulated by retinal disparity
  8. What is proximal vergence?
    voluntary convergence- due to knowlede that the object is nearby
  9. What is accommodative vergence?
  10. What is the physiological position of rest?
    position the axes take when stimuli to fusion is absent
  11. What happens if you do not have enough tonic vergence?
    fusional divergence has to bring it back to ortho= amount of phoria
  12. What happens if you have too much tonic vergence?
    fusional convergence has to make up for it
  13. what is the relationship between accommodation and convergence?
    phoria depends on the amount of convergence that accompanies each dioptre of accommodation
  14. Compensated phoria?
    does not cause symptoms
  15. Decompensated phoria?
    thought to generate suppression
  16. tonic aetiology of phoria?
    • tonic position gives deviation
    • muscle weak/inserted incorrectly- rare
  17. neural aetiology of a phoria?
    interaction between vergence and accommodation is abnormal
  18. rx and aetiology of phoria?
    uncorrected hyp- overconverge
  19. What are some symptoms of high phoria?
    • aesthnopia
    • HA
    • transient blur/diplopia
    • avoidance of near work
    • loss of place while reading
    • words running together while reading
  20. How to manage high phoria?
    • specs
    • vision training
  21. aetiology of tropia?
    • possible muscle weakness
    • same as phoria
  22. sensory anomalies associated with tropias?
    • diplopia: superimposition causing confusion
    • suppression: adult-> diplopia, in macular to avoid confusion
    • ambyopia: strab- occur in deviating eye as a result of continued suppression
    • rx- uncorrected aniso or astig
    • anomalous correspondence- one fovea of the eye doesnt correspond with the other
    • can fix diplopia and confusion
  23. What is the management of tropias?
    specs, occlusion, vision training, surgery, botox
  24. What is a nystagmus
    A regularly repetitive, rapid involuntary movement of the eye
  25. What is aniseikonia?
    unequal image size and shapes
  26. concomitant?
    angle of tropia is same in all directions of gaze
  27. incomitant?
    angle differs in different directions of gaze