BV Study Notes 3 PDF

Study Slides The story so far………….  Eye examinations should include assessing College of and recording habitual ocular muscle balance and the method used, at least Optometrist cover test for distance and near. This should be done with the...

Study Slides The story so far………….  Eye examinations should include assessing College of and recording habitual ocular muscle balance and the method used, at least Optometrist cover test for distance and near. This should be done with the habitual guidelines: perception and/or without prescription, if appropriate If you feel clinically appropriate you may: Measure convergence Assess ocular motility  Comitant – angle of deviation is constant in all Comitant and directions of gaze incomitant Incomitant – angle of deviation varies with deviations direction of gaze Congenital or acquired? Acquired may indicate systemic disease. Maybe due to paralysis, paresis (caused by nerve damage) or mechanical restriction of one or more extra-ocular muscle.  Associations Amblyopia Sensory adaption Hyperopia Poor stereopsis Diplopia Movements of both eyes Versions – both eyes move in the same direction Movements of both eyes Versions – both eyes move in the same direction DEXTROVERSION – RE abducts, LE adducts Movements of both eyes Versions – both eyes move in the same direction Movements of both eyes Versions – both eyes move in the same direction LEVOVERSION – RE adducts, LE abducts Movements of both eyes Vergences – both eyes move in the opposite direction Movements of both eyes Vergences – both eyes move in the opposite direction CONVERGENCE – RE and LE adduct Movements of both eyes Vergences – both eyes move in the opposite direction Movements of both eyes Vergences – both eyes move in the opposite direction DIVERGENCE (RE and LE abduct)  Heterophoria is a LATENT Key Words deviation Heterotropia is a MAIFEST deviation  If the phoria is controlled, it is called Heterophoria ‘compensated’. This means that in the Prescence of a binocular and stimulus, no manifest deviation is present, the deviation is only present when the eyes are decompensati dissociated. If the phoria is ‘decompensated’, the deviation is present even in the presence of a binocular on stimulus, causing blur, diplopia and fatigue. Thus, a phoria can break down or ‘decompensate’ into a tropia. Poor accommodation or convergence can cause stress on the binocularity and result in a phoria decompensating, particularly at near. EOM Palsies and Pareses Palsy indicates Paresis indicates total loss of a weakness in function of and function of an EOM EOM Extraocular muscle innervation Superior Oblique (SO) – cranial nerve IV (Trochlear) Inferior Oblique (IO) – cranial nerve III (Oculomotor) Superior Rectus (SR) – cranial nerve III (Oculomotor) Inferior Rectus (IR) - cranial nerve III (Oculomotor) Medial Rectus (MR) - cranial nerve III (Oculomotor) Lateral Rectus (LR) - cranial nerve VI (Aducens) LR6ASO4TAO3O The Cover Test 3. If no tropia or phoria, 2. If no tropia 1. Search for a perform search for a tropia subjective phoria cover test (Phi test) Phi With – Exo Against - ESO movements: The Cover Test Measure Measure EXO with ESO with base IN base OUT The Cover Test A tropia Phorias do MUST be NOT usually referred to have a left or as a left or right right More tests for phoria – Maddox Rod Base IN Base OUT  More tests for phoria – Maddox Rod Base DOWN Base UP More tests for phoria For Near Maddox Wing Fixation Disparity Distance: Alligned EXO disparity (both eyes) EXO disparity (LE only) LE OXO OXO OXO RE Fixation Disparity Distance: Alligned ESO disparity (both eyes) Vertically aligned LE O OXO OXO OX RE Fixation Disparity Near Mallet Unit  Bagolini lenses Suppression Worth 4 – dot test Ocular Motility Test STAR MOTION H MOTION Ocular Motility Test Any reported diplopia Any reported discomfort Any under or overaction in one eye. Overaction of a horizontal rectus muscle is graded according to the amount of cornea covered by the canthus; in extreme overaction (+4), half of the cornea is concealed. Any pursuit movements that are not smooth Any difference in size of palpebral apertures in any direction of gaze What is diplopia reported? Find the direction where diplopia images are furthest apart. H What if diplopia is reported? Establish which eye is seeing each image A/V/X/Y Patterns You can watch all the video, but we are only concerned with the AVXY patterns discussed up to 1:12 secs in the video  Strabismus refers to the misalignment A/V/X/Y/ of the eyes, where they do not properly coordinate with each other to focus on Lambda the same point. In certain cases of strabismus, the misalignment can change depending on the direction the person is looking, and these changes follow distinct patterns, typically described as A, V, X, Y, or λ (lambda) patterns. These patterns are named based on how the degree of misalignment changes when looking up and down.  1. A-pattern Strabismus 2. V-pattern Strabismus Here’s a Description: In A-pattern strabismus, the eyes are Description: In V-pattern strabismus, the eyes are breakdow more esotropic (inward- turning) when looking more exotropic (outward- turning) when looking n of each upward and more exotropic upward and more (outward-turning) when esotropic (inward-turning) looking downward. when looking downward. pattern: Pattern: The amount of eye misalignment decreases Pattern: The alignment changes in such a way that when looking down, the eyes diverge more resembling the shape of the when looking upward, letter "A." resembling the shape of Cause: This pattern can the letter "V." occur due to overaction of Cause: This can be due to the superior oblique overaction of the inferior muscles or underaction of oblique muscles or the inferior oblique underaction of the muscles. superior oblique muscles.  3. X-pattern Strabismus Y-pattern Strabismus Description: In X-pattern Description: In Y-pattern strabismus, there is more strabismus, the eyes are more exotropia (outward deviation) exotropic (outward-turning) in both upward and when looking upward but have downward gaze than in less or no exotropia in primary (straight-ahead) downward gaze. The eyes gaze. form a pattern similar to the shape of the letter "Y." Pattern: The misalignment is greater in both extremes Pattern: The deviation is of upward and downward larger in upgaze, and it tapers gaze but decreases in the off when looking straight center, forming a rough "X" ahead or down. shape. Cause: This may be related to Cause: It’s less common and issues with the medial rectus might be due to a muscles or specific combination of oblique combinations of the rectus and muscle abnormalities or oblique muscles. variations in the orbital structure.  Lambda (λ)-pattern Strabismus Description: Lambda (λ)- pattern strabismus shows a combination of horizontal and vertical deviations that vary with upgaze and downgaze, creating a pattern resembling the Greek letter lambda (λ). Pattern: The eyes may move in such a way that they form a lambda shape with upward and downward gaze. The vertical component distinguishes it from purely horizontal patterns like the A or V. Cause: It can result from complex issues in both vertical and horizontal rectus muscles.  Clinical Relevance: A- and V-patterns are the most common and can cause noticeable functional Treatment typically and cosmetic issues. involves eye muscle Recognizing the Children with these surgery to balance specific pattern in patterns may develop the tension in the strabismus is critical compensatory head oblique or rectus for appropriate tilts or chin positions muscles, depending diagnosis and to avoid the on which muscles are surgical planning. misalignment, which causing the pattern. can lead to further problems like neck strain. Each strabismus pattern A-pattern Strabismus (A, V, X, Y, λ) exhibits different misalignment Upgaze: 15 PD esotropia (inward characteristics deviation) depending on the Primary gaze: 10 PD esotropia direction of gaze. Here are some Downgaze: 5 PD esotropia examples of strabismus patterns This means that when looking upward, in prism diopters the eyes turn inward more (15 PD), (PD): and the deviation decreases in downward gaze (only 5 PD), creating an "A" pattern.  Upgaze: 15 PD exotropia (outward 2. V-pattern deviation) Strabismus Primary gaze: 5 PD exotropia Downgaze: 0 PD or even 5 PD esotropia (inward deviation) In this case, when the patient looks upward, the eyes turn outward more (15 PD exotropia), and the deviation reduces or even reverses in downward gaze, forming a "V" shape. V Pattern XOT  Upgaze: 20 PD exotropia 3. X-pattern Primary gaze: 10 PD exotropia Strabismus Downgaze: 20 PD exotropia In X-pattern strabismus, there is more outward deviation in both upward (20 PD) and downward gaze (20 PD), with less misalignment in primary gaze (10 PD). This forms the X-shaped misalignment.  Upgaze: 20 PD exotropia 4. Y-pattern Primary gaze: 10 PD Strabismus exotropia Downgaze: 0 PD In Y-pattern strabismus, there is significant outward deviation in upgaze (20 PD), but the deviation becomes almost non-existent in downgaze (0 PD). This creates a "Y" shaped pattern.  Upgaze: 20 PD exotropia with 5 PD 5. Lambda hypertropia (upward vertical deviation) Primary gaze: 10 PD exotropia with 2 (λ)-pattern PD hypertropia Downgaze: 5 PD exotropia, no Strabismus hypertropia In λ-pattern strabismus, both horizontal and vertical deviations are seen, and they vary with gaze. For example, exotropia (20 PD) and hypertropia (5 PD) may be larger in upgaze, and the deviation diminishes as the gaze moves downward, forming a λ- like shape.  You are looking at the Main consideration are Points to pattern it is forming A and V patterns – remember: and the deviation of the eye in others are rarely seen. combination. Remember a V Only significant if 15PD pattern can occur in from down gaze to up SOP 5PD upgaze, gaze. 10PD primary, 15PD Important to note what downgaze – this is deviation is it - is it least convergent in ESO or EXO. upgaze. This will help you to know at which point the deviation will increase in PD or decrease in PD.  The “A” is derived as a simple way of describing that the The ‘V’ is derived by inward drift is greater the drift being greater in superior gaze as in superior gaze or compared to either least convergent. primary or inferior gaze. In the context of eye movement and strabismus, the terms agonist and antagonist refer to pairs of muscles that work together to control the position of the eyes. These muscles ensure smooth and coordinated movements in all directions. Here’s an explanation of these terms and their roles: Agonist Muscles Definition: The agonist muscle is the primary muscle responsible for moving the eye in a specific direction. Function: When an eye moves in a certain direction, the agonist muscle contracts to pull the eye into that position. For example, if you look to the right, the right lateral rectus muscle is the agonist, because it pulls the right eye outward (abduction). Antagonist Muscles Definition: The antagonist muscle is the muscle that works in opposition to the agonist, relaxing while the agonist contracts. Function: As the agonist contracts to move the eye, the antagonist must relax to allow this movement. Using the same example of looking to the right, the right medial rectus muscle is the antagonist, since it relaxes to permit the outward movement of the eye. How Agonist and Antagonist Muscles Work Together: The eye muscles work in coordinated pairs to control movement. Each eye has six extraocular muscles, which are divided into two main types based on the directions they move the eye: Rectus muscles: These control up, down, left, and right movements. Oblique muscles: These control more complex movements like rotation or torsion. The Role of Synergists: In some movements, muscles act as synergists to assist the primary agonist muscle. For example, in upward gaze, the inferior oblique assists the superior rectus in elevating the eye. The inferior rectus (antagonist) must relax to permit this movement. Summary of Agonist-Antagonist Relationships: Eye movements in each direction require the agonist muscle to contract, pulling the eye in the desired direction. The antagonist muscle must relax to allow smooth movement. Both eyes move together in a coordinated fashion, using corresponding muscles in both eyes for movements like looking to the right, left, up, or down. Ipsilateral Muscles Definition: Muscles that are on the same side of the body or head as the movement or the nerve controlling them. Example in Eye Movement: If we are talking about the right lateral rectus muscle, it is an ipsilateral muscle when referring to the right eye. This means that the right lateral rectus muscle controls the movement of the right eye outward (abduction), and it is located on the same side as the right eye. Contralateral Muscles Definition: Muscles that are on the opposite side of the body or head relative to a specific eye movement or nerve signal. Example in Eye Movement: When discussing horizontal eye movement, if we focus on the right lateral rectus, its contralateral counterpart is the left medial rectus, which moves the left eye inward (adduction). These two muscles are coordinated for gaze shifts to the right, with one acting as the ipsilateral muscle and the other as the contralateral muscle.  Ipsilateral muscles: The muscles on the Summary of same side of the body/eye as the movement. Example: right lateral rectus Key Concepts: for right gaze. Contralateral muscles: The muscles on the opposite side of the body/eye. Example: left medial rectus for right gaze. Eye movements, especially horizontal movements, require yoked pairs of ipsilateral and contralateral muscles to coordinate properly, allowing both eyes to focus on the same target.