Clinical Skills 2 - B - orthoptics examination (ocular motility and squint) Flashcards
Orthoptics leads in investigation, diagnosis and treatment of defects of binocular vision and abnormalities of eye movements When do you look for in the eye before performing a cover test to diagnose a manifest squint?
Look for symmetrical corneal reflections with a pen light
If the corneal reflections ae not symmetrical then a cover test is carried out to detect a manifest squint What is a manifest squint also known as?
Akso known as a tropia - Manifest or latent: manifest squint is present when the eyes are open and being used, whereas in latent squint the eye turns only when it is covered or shut.
What is the broader category of tropia known as - it means cross eyed?
Strabismus -aka squint is a condition in which the eyes do not properly align with each other when looking at an object.
How is a cover test carried out? What is required for it?
Require an occluder and a near and a distance fixation target In the testing you cover one eye with an occluder and look at the other eye to see if it moves direction
Manifest squints can cause diplopia due to the eyes not being in symmetrical location What is the terminology for when using an occluder the abnormal eye moves Outward? Inward? Downward? Upwards?
Eye moves: Outward - Esotropia - eye starts slightly medial Inwards - exotropia - eye starts slightly lateral Upward - hypotropia - eye starts slightly superior Downward - hypertropia - eye starts slightly inferior
What two distances are the cover test carried out at?
The cover test is carried out at 1/3 rd of a metre and asking the patient to look at an object 6 metres away
In a child with a squint, the brain can stop using the squint eye causing what?
This can cause the child to have a lazy eye (Lazy eye, also known as amblyopia, is an early childhood condition in which a child’s eyesight does not develop as it should in one eye. When a patient has amblyopia, the brain focuses on one eye more than the other, virtually ignoring the “lazy” eye)
Assessing ocular motility Is the lateral rectus eye muscle used more or less when looking for short or long distance objects? What nerve supplies this muscle?
Lateral rectus is more useful for long distance as the eyes need to slightly part Supplied by abducent nerve
When assessing ocular motiltity and you find a problem with the abducent nerve, do you stop or continue? Also do you use a finger or pen torch when examining?
You continue to make sure you have assessed all directions of ocular movement Use a pen torch so you can still see the corneal reflections
What CN damage would cause this?
Right Oculomotor (CN III) Palsy
What is seen in the eyes on a sixth nerve palsy?
Abducent nerve Lateral rectus Eye is more medially located Horizontal diplopia Connot move laterally from midline Squint begins in midline
When assessing ocular motility, you get the patient to follow a pen If the patient is to follow the pen medially/laterally or superior/inferior and there is visible sclera when moving What does this show?
Visible sclera means there is a weak muscle
When assessing the ocular motility, what will be seen if the patient has a CN IV or CN VI palsy?
Trcohlear nerve - eye will be unable to move downwards and in Abducent - eye wont be able to move laterally
Due to a sixth nerve palsy, what type of squint will a patient have when examinign for a manifest squint?
Patinet will have a horizontal diplopia due to the esotropia (eye lies slightly medially due to the weak lateral rectus)
If palsy exists in CN III, IV and VI , what can be a cause of all of these palsies?
Cavernous sinus pathology Superiror orbital fissure pathology Myasthenia gravis - rare long-term condition that causes certain muscles to become weak
