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

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

Description Method Unilateral Cover Characterization of strabismus 28 Direction Frequency Magnitude Laterality comitance Theme 6: Cover test

Description Cover – Uncover Characterization of strabismus 58 Direction Magnitude comitance Cover – Alternating Theme 6: Cover test

Self-evaluation 69 Bibliography 79 Theme 6: Cover test

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. Utility

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

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

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

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

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

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

fle fre 0 Occlud- er 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 What is a strabismus? Utility

Paralysis of the OS from the RE Torticollis 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. What is a strabismus? Utility Habitual position Ocular deviation

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 A phoria is a latent deviation. This deviation becomes apparent after the elimination of the fusion stimulus (occluder, Maddox rod, prisms...) What is a phoria? Utility

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

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

Accomodative card Occluder Optotype from distance Prisms Material

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

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

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

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

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

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

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

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

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 Unilateral Cover Method e flefre

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

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

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

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

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

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

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

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

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

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

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

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. Unilateral Cover Characterization of the strabismus Magnitude Method

But what does the prism do? fle fre 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. 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 Unilateral Cover Characterization of the strabismus Magnitude Method

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

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

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

In vertical deviations, it depends on the eye on which the prism is situated 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 Unilateral Cover Characterization of the strabismus Magnitude Method

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

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

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

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

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

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. Unilateral Cover Characterization of the strabismus INcomitance Method

ComitanceIncomitance Deviation Differences inferior to 7D in distinct vantage points Differences superior to 7D in distinct vantage points There is no limitation in versions or in ductions There is limitation in versions and/or in ductions Unilateral Cover Characterization of the strabismus Incomitance Method

Unilateral Cover Method Characterization of the strabismus Incomitance Supraversion Primary position InfraversionInfra dextroversionInfra levoversion Supra dextroversionSupra levoversion Dextroversion Levoversion

Cover - Uncover Method Alternating Cover Test Unilateral Cover Detection of phoria Evaluation of the totality of the deviation Detection of strabismus Objective Through occlusion and analysis of the observations Method

Cover - Uncover Detection of phoria Cover an eye and observe if uncovering it results in movement of any type e flefre Movement? Method

Cover - Uncover Detection of phoria Observe if any movement of the eye that is covered is produced e flefre After the occluder is eliminated the fixation stimulus and the eye are situated in the passive position. The evaluation of the passive position Determines the existence of a phoria. If when taking away the occluder the covered eye moves, we are facing a phoria. Method

If when covering the right eye, it takes a passive position so that when it is uncovered it needs to move in order to fixate, we are faced with a phoria. The presence of movement reveals a phoria e fle fre e flefre Cover - Uncover Detection of phoria e flefre Method

If the uncovered eye moves, we are faced with a phoria After detecting a phoria these factors must be characterized: Direction Magnitude Comitance Cover - Uncover Detection of phoria e flefre Method

Characterization of a phoria: Direction Magnitude Comitance Cover - Uncover Method

When covering the right eye, it takes its passive position behind the occluder When uncovering we can find that… It moves in a vertical sense upward downward Hyperphoria Hypophoria It moves in a horizontal sense inward Endophoria outward Exophoria It does not move Orthophoria Cover - Uncover Characterization of the phoria Direction Method

If when uncovering the right eye, It moves horizontally… e flefre outwards Endophoria Cover - Uncover Characterization of the phoria Direction Method

If when uncovering the right eye, it moves horizontally… e foifod inward Exophoria Cover - Uncover Characterization of the phoria Direction Method

If when uncovering the right eye, it moves vertically… e fle fre upward Hypophoria Cover - Uncover Characterization of the phoria Direction Method

If when uncovering the right eye, it moves vertically… downward Hyperphoria e foi fod Cover - Uncover Characterization of the phoria Direction Method

Cover - Uncover Method Alternating Cover Test Unilateral Cover Detection of phoria Evaluation of the totality of the deviation Detection of strabismus Objective Through occlusion and analysis of the observations Method

Pass the occluder from one eye to the other repeatedly without allowing fusion. Evaluate the existence of movement in the eye that is fixating. e flefre Movement? Alternating Cover Test Evaluation of the totality of the deviation Method

Observe if movement of the eye that is uncovered is produced. e flefre After the occluder is eliminated the fixation Stimulus and the eye are situated in passive positions Not allowing fusion to be produced makes the Movement being observed clearer Phoria and tropia are not differentiated Alternating Cover Test Evaluation of the totality of the deviation Method

If when passing the occluder from one eye to another the uncovered eye moves… Alternating Cover Test Evaluation of the totality of the deviation e flefre e fle fre e flefre Method

If the uncovered eye moves, the type of deviation* will have to be characterized: Direction Magnitude Comitance Alternating Cover Test Evaluation of the totality of the deviation e flefre Phoria or tropia (*See the characteristics in prior sections) Method

Self-evaluation Exercises

Give a name to the following conditions according to the observations realized during the cover test. Exercises

Example 1. Exercises

Example 1. Orthotropia Exercises

Example 2. Exercises

Example 2. Constant Endotropia LE Exercises

Example 3. Exercises

Ejemplo 3. Constant Exotropia LE Exercises

Example 4. Exercises

Example 4. Constant Hypotropia LE Exercises

Bibliography

Von Noorden GK. Atlas de estrabismos. Madrid: Mosby-Ciagami, 1997 Caloroso EE, Rouse MW. Tratamiento clínico del estrabismo. Madrid: Ciagami, 1999 Hugonnier R. Hugonnier S. Estrabismos heteroforias y parálisis oculomotrices. Barcelona: Toray-Masson, 1977 Prieto-Díaz J, Souza-Dias C. Estrabismo (5ª ed.). Buenos Aires : Ediciones Científicas Argentinas, 2005 Von Noorden GK, Helveston EM. Estrabismos. Decisiones clínicas. Madrid: Ciagami, 1997 Borràs MR et al. Visión binocular. Diagnóstico y tratamiento. Barcelona. Ediciones UPC, 1996 Bibliography Computer program OSP2