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BLOCK 1: Clinical Exams

BLOCK 1: Clinical Exams. Theme 1: Anamnesis Theme 2: Material Theme 3: Visual acuity Theme 4: Retinoscopy Theme 5: Subjective Theme 6: Cover Test Theme 7: Accomodation. Theme 6: Cover test. Utility. 6. 7. What is a strabismus?. 15. What is a phoria ?. Material. 18. Method.

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BLOCK 1: Clinical Exams

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  1. BLOCK 1: Clinical Exams Theme 1: Anamnesis Theme 2: Material Theme 3: Visual acuity Theme 4: Retinoscopy Theme 5: Subjective Theme 6: Cover Test Theme 7: Accomodation

  2. Theme 6: Cover test Utility 6 7 What is a strabismus? 15 What is a phoria? Material 18 Method 19

  3. Theme 6: Cover test Method 19 20 Unilateral Cover 21 Description 28 Characterization of strabismus 30 Direction Frequency 36 38 Magnitude 45 Laterality 49 comitance

  4. Theme 6: Cover test 53 Cover – Uncover 54 Description 58 Characterization of strabismus 59 Direction 59 Magnitude comitance 59 64 Cover – Alternating

  5. Theme 6: Cover test Self-evaluation 69 79 Bibliography

  6. Utility The cover test is an optometric test that can prove or disprove the presence of a strabismus or a phoria. The presence or absence of the fusional ability is determined.

  7. Utility What is a strabismus We are facing a strabismus when both eyes do not simultaneously direct their visual axes on object of interest…. fle fre What happens when an ocular deviation is produced? axis

  8. fre fle Utility What is a strabismus When binocular vision exists, the object of interest stimulates both foveas simultaneously, thereby achieving a fusion of the image on a cortical level. In this case, what is called a Normal Sensory Correspondence (NSC) exists.

  9. 0 fle + fre = fre + = Confusion fle fle + O = + = Diplopia Utility What is a strabismus • Facing an ocular deviation, the following effects could • be produced: • diplopia • confusion

  10. 0 fre fle Utility What is a strabismus? • Facing these possibilities and uncomfortable effects, • the visual system can respond by trying to avoid • them through: • Abnormal retinal correspondence • Suppresion • Eccentric fixation • Torticollis

  11. 0 fre fle ARC Utility What is a strabismus? Abnormal retinal correspondence The fovea of the deviated eye will not correspond with fixating eye, thereby resulting in the binocular function, point “0”.

  12. 0 fod fle Utility What is a strabismus? Suppression The image that prevails is that which only pertains to the directing eye.

  13. Occlud-er 0 fre fle Utility What is a strabismus? Eccentric fixation It happens when the deviated eye, in a monocular way, prefers to look at the object of interest with a distinct point of the fovea

  14. Utility What is a strabismus? Torticollis Habitual position There are different types of strabismus in which diplopia and confusion only appear in certain “sight” positions This can make the patient present an inclination of the head in order to maintain, “in a habitual way”, sight in the position of greatest comfort. Ocular deviation Paralysis of the OS from the RE

  15. Utility What is a phoria? A phoria is a latent deviation. This deviation becomes apparent after the elimination of the fusion stimulus (occluder, Maddox rod, prisms...) The visual axes of both eyes are directed at the object of interest thanks to the utilization of fusional convergence A phoria at a given distance implies that, at that distance and in that instant, binocular vision exists

  16. Utility What is a phoria? fre fle The type of fusional convergence to utilize depends on the type of phoria An endophoria utilizes the negative fusional vergence (NFV)in order to bring both visual axes onto the object of interest. NFC c

  17. Utility What is a phoria? fre fle An exophoria utilizes the positive fusional vergence (PFV) in order to bring the visual axes onto the object of interest. CFP c

  18. Material • Optotype from distance • Accomodative card • Occluder • Prisms

  19. Objective Detection of strabismus Detection of phorias Evaluation of the totality of the deviation Method By covering one of the two eyes and analyzing what is observed Unilateral Cover Cover - Uncover Alternating Cover Test

  20. Objective Detection of strabismus Detection of phorias Evaluation of the totality of the deviation Method By covering one of the two eyes and analyzing what is observed Unilateral Cover Cover - Uncover Alternating Cover Test

  21. Method Unilateral Cover Detection of strabismus Cover and uncover an eye, observing if in the other eye some movement of fixation is produced fre fle Movement? e

  22. fre fle Hide the left eye e Method Unilateral Cover If upon covering the right eye… 1. There is No movement of the left eye fre fle e The absence of movement tells of orthotropia (absence of strabismus)

  23. Method Unilateral Cover Detection of strabismus Observe whether movement of the uncovered eye fre fle 1. There is no movement • Possible Orthotropia • (there is no strabismus) Movement? 2. There is movement • Tropia • (there is strabismus) e

  24. Hide the left eye fre fle fre fle e e Method Unilateral Cover If upon hiding the right eye… 1. There is No movement of the left eye The absence of movement tell of orthotropia (absence of strabismus)

  25. fre fle fre fle e e Method Unilateral Cover If upon covering the right eye… 2. There is movement of the left eye Indicates that the left eye was deviated The presence of movements tells of strabismus

  26. fre fle fre fle e e Method Unilateral Cover If upon hiding the right eye… 2. There is movement of the left eye It indicates that the left eye was deviated Endotropia LE

  27. fre fle e Method Unilateral Cover If upon covering the right eye … 2. There is movement of the left eye After detecting a strabismus it must be characterized: • Direction • Frequency • Magnitude • Laterality • comitance

  28. Method Unilateral Cover Characterization of the strabismus: • Direction • Frequency • Magnitude • Laterality • Comitance

  29. Method Unilateral Cover Characterization of the strabismus: • Direction • Frequency • Magnitude • Laterality • comitance

  30. Method Unilateral Cover Characterization of the strabismus: • Direction • Frequency • Magnitude • Laterality • comitance

  31. Method Characterization of the strabismus Direction Unilateral Cover If upon covering the right eye, the left eye moves… There is a strabismus Vertical movement... Horizontal movement... upwards inwards Hypotropia Exotropia downwards Hypertropia Endotropia outwards

  32. fle e fre Method Characterization of the strabismus Direction Unilateral Cover The left eye moves vertically UPWARDS If upon covering the right eye, Hypotropia LE

  33. foi e fod Method Characterization of the strabismus Direction Unilateral Cover If when covering the right eye, the left eye moves vertically UPWARD Hypertropia LE

  34. fre fle e Method Characterization of the strabismuc Direction Unilateral Cover the left eye moves horizontally OUTWARD If when covering the right eye, Endotropia LE

  35. fre fle e Method Characterization of the strabismus Direction Unilateral Cover If when covering the right eye, the left eye moves horizontally INWARD Exotropia LE

  36. Method Unilateral Cover Characterization of the strabismus Frequency Characterization of the strabismus: • Direction • Frequency • Magnitude • Laterality • Comitance

  37. Method Unilateral Cover Characterization of the strabismus Frequency Given a concrete distance we can find that.. A strabismus is present Always Sometimes Intermitent strabismus Constant strabismus Greater probability of Sensory adaptations (amblyopías, eccentric fixations, suppressiones, anomalous correspondence) Binocular vision is present sometimes

  38. Method Unilateral Cover Characterization of the strabismus: • Direction • Frequency • Magnitude • Laterality • comitance

  39. Method Unilateral Cover Characterization of the strabismus Magnitude In order to evaluate the magnitude of the deviation we are going to rely on the alternating cover test with prisms. The alternating cover test consists in passing the occluder from one eye to the other without allowing the possibility of fusion. In this moment we evaluate the type of movement. The placement of the situated prisms in the appropriate position will make the movement cease. The prismatic quantity that makes the movement cease during the alternating cover test tells of the total measurement of the deviation.

  40. fre Method Unilateral Cover Characterization of the strabismus Magnitude But what does the prism do? When facing an ocular deviation, the deviated eye, when incited to fixate due to the covering of the fixating eye (supposing central fixation), will have to realize movement in order to direct its fovea towards the object of interest. fle The prism corresponding to the magnitude of the deviation makes it so that the eye does not need to move towards the object of interest since through the prism the image of this object has been situated along the visual axis

  41. fre fle Method Unilateral Cover Characterization of the strabismus Magnitude But what does the prism do? fre fle Movement during the cover test

  42. fre fre Occluder Method Unilateral Cover Characterization of the strabismus Magnitude But what does the prism do? fre fle fle fle That prism that ceases the movement provides us with the magnitude of the deviation Occluder

  43. ENDODEVIATIONS: Temporal bases (BT) EXODEVIATIONS: Nasal bases (BN) Method Unilateral Cover Characterization of the strabismus Magnitude The base of the prism depends of the type of deviation

  44. Left HYPOTROPIA: Superior bases (SB) in front of the left eye Inferior bases (IB) in front of the right eye Left HYPERTROPIA: Superior bases (SB) in front of the right eye Inferior bases (IB) in front of the left eye Method Unilateral Cover Characterization of the strabismus Magnitude In vertical deviations, it depends on the eye on which the prism is situated

  45. Method Unilateral Cover Characterization of the strabismus: • Direction • Frequency • Magnitude • Laterality • Comitance

  46. Method Unilateral Cover Characterization of the strabismus Laterality The strabismic eye can always be the same or it can be both in an alternating pattern The strabismic eye can be… Always the same The right or left eye Unilateral strabismus Alternating strabismus Greater probability of Sensory adaptations (amblyopias, eccentric fixations, suppressiones, anomalous correspondence)

  47. Method Unilateral Cover Characterization of the strabisums Laterality Always the same Unilateral strabismus The deviated eye is always the LE

  48. Method Unilateral Cover Characterization of the strabismus Laterality Alternating strabismus The deviated eye can be one or the other

  49. Method Unilateral Cover Characterization of the strabismus: • Direction • Frequency • Magnitude • Laterality • Comitance

  50. Method Unilateral Cover Characterization of the strabismus INcomitance It is a characteristic of the ocular deviations that is related to their etiology. It will be evaluated in various ways: • Quantifying the deviation depending on the vantage point. • Evaluating the existence of limitations in versions or ductions.

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