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OPTICS
Optics
| What is Accommodation? | The ability of one eye to change focus for objects viewed at different distance. -for each unit dipper of accommodation exerted, a given amount of convergence also occurs. 33cm 6m |
| What is Diopter? | A unite of measurement of the power of a prism. 1 diopter brings parallel rays of light to focus at a distance of 1 meter. |
| What is Refractive Error? | A condition where parallel rays of light entering the eye do not come to a focus properly on the retina. |
| What is Emmetropia? | Normal refractive error. |
| what is Hyperopia? | Farsightedness (hypermetropia) lights come in focus BEHIND the eye. (globe is smaller then average). |
| what is Myopia? | Nearsightedness lights come in focus IN FRONT of the eye. (globe is usually bigger then average). |
| what is Astigmatism? | Prevents lights from coming into a single focus on the retina because of different degrees of the retraction in various meridians of the eye. |
| what is Anisometropia? | Refractive error of the eye is unequal. |
| what is Mydriasis? | Enlargment (dilation) of the pupils. happens in dark or when using certain pharmacological agents. |
| what is Miosis? | Constriction of the pupil. occurs when accommodating, bright light stimulus, or certain pharmacological agents. |
| what is Nystagmus? | eyes make short, rhythmic movements when they should be static. |
| what is Ptosis? | Drooping or abnormal closure of the eye lids. |
| what is Abduction? | Rotation of the eye outward (toward the temple) |
| what is Adduction? | rotation of the eye inward towards the nose. |
| what is Bielschowsky heads tilt test? | a diagnostic test used to identify the weak muscle in cases where a vertical deviation its present. |
| what is Bifoveal fixation? | a state in which the object of regard is imaged on both foveae at the same time given rise to binocular single vision. |
| what is Binocular single vision? | the ability to use both eyes together to see objects as one. |
| what is Conjugate movements (versions)? | movement of both eyes in the same direction. > > or << or ^^ etc. |
| what is Convergence? | movements of both eyes towards the midline. > < |
| what is Depression? | movement of both eyes downwards. |
| what is diplopia? | Double vision. |
| what is Disjugate movements (vergences)? | movements of the two eyes in opposite directions, as in covariance and divergence. (>)(<) (<) (>) |
| what is dissociation? | disruption of fusion. |
| what is divergence? | Disjunctive movements of bOTH eyes away from the midline. (<) (>) |
| what is elevation? | movement of both eyes upward (^)(^) |
| what is emmetropia? | No refractive error. |
| what are the 6 extraocular muscles? | medical rectus, lateral rectus superior rectus inferior rectus superior oblique inferior oblique |
| what are the primary and secondary actions for medical and lateral rectus? | medical rectus primary: adduction secondary none lateral rectus primary: abduction secondary none |
| what are the primary and secondary actions for the superior and inferior rectus? | superior rectus primary: elevation secondary: intorsion, adduction inferior rectus primary: depression secondar: extorsion, adduction |
| what are the primary and secondary actions for the superior and inferior obliques? | superior oblique primary: intorsion secondary: depression, abduction inferior oblique primary: extorsion secondary: elevation,abduction |
| what is a fixation point? | the object of attention or object of regard. |
| what is fixing eye? | the straight eye, the eye that looks at the object of regard. |
| what is the fovea and where is it located? | The fovea is is the area of the retina that has the capability of most distinct vision. Located in the center of the macula. |
| what is fusion? | the mental ability to blend two similar images (one formed on each retina) and perceive them as one. |
| what is Heterophora (phoria)? | a deviation that is present only when fusion is disrupted, a LATENT deviation. |
| what is hyperdeviation? | it is upward deviation of ONE eye. |
| what is heterotropia (tropia)> | a misalignment of the visual axes as in esoTROPIA or exoTROPIA, a MANIFEST deviation. |
| what is hyperopia? and what type of lens do we use to correct for it? | farsightedness, the rays of light come a focus behind the eye. Corrected with a CONVEX (plus) lens. (_) |
| what is hypodeviation? | downward deviation of ONE eye. |
| true or false | constant (tropic ) intermitten, or latent (phoric) |
| what type of deviations can there be? | eso- exo- hyper- hypo- and they can all be constant, or intermittent, or latent deviation. |
| whats intorsion? | wheel like rotation of the eyes moves towards the midline. |
| what is extorsion? | wheel like rotation of the eyes moves away from the midline. |
| what is miosis? | contraction of the pupil as normally occurs when accommodating or stimuli to bright lights can also be pharmacologically induced. |
| what is mydriasis? | enlargement of the pupil as normally occurs when its dark or when certain pharmacologically are used. |
| what is myopia and what type of lens do we use to correct for it? | Nearsightedness, rays of light come to focus in front of the eye. we correct this by using a CONCAVE (minus) lens. )_( |
| what is nystagmus? | A condition in which the eyes make short, rhythmic movements while they normally should be static |
| what is occlusion? | a method of patching one eye to insure use of the other eye. |
| what is the name of the right eye? | Oculus Dexter (OD) |
| what is the name of the left eye? | Oculus Sinster (OS) |
| what is the name for both eyes together? | Oculi Unitas (OU) |
| what is Orthophoria? | Straight eyes, the normal position of eyes. |
| what is Paralysis? | The complete inability of an extraocular muscle to act. |
| whats the straight ahead position of the eyes called? | Primary position. |
| what three cranial nerves supply innervation to the extraocular muscles? | 3rd cranial nerve : Oculomotoer nerve 4th CN: Trochlear nerve 6th CN : Abducens nerve |
| where does the 3rd CN Oculomotor enter the eye? What does the 3rd CN Oculomotor nerve do for the eye? | It enters the orbit via the superior orbital fissure and innervates muscles that enable most movements of the eye and that raise the eyelid. |
| What eye muscles does the 3rd CN innervate? | inferior rectus, medial rectus, superior rectus, inferior oblique and levator palpebrae. |
| What does the 4th CN, trochlear nerve, do for the eye and what muscle does it innervate? | motor nerve that innervates the superior oblique muscle which operates through the pulley-like trochlea to which allows it to have the intorsion, abduction, and depression movements. |
| What does the 6th CN do for the eye muscles, and what muscle does it innervate? | The abducens nerve is a nerve that controls the movement of the lateral rectus muscle, responsible for outward gaze. |
| what are paired primary movers called? | Yoke muscles, which when paired produce coordinated movements in the 8 cardinal gazes. |
| what are we testing when we test yoke muscles? | Version testing. (elevation depression in both eyes. ) |
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Hebaalbaiaty
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