terms Flashcards
aberrant regeneration
change in actions of muscles supplied by third nerve following traumatic/compressive 3rd nerve palsy (new nerve innervation)
ABSV
abnormal binocular single vision: form of BV occurs in absense of foveal fixation usually with abnormal retinal correspondence
Abnormal Retinal Correspondence
A binocular condition in which there is a change in a visual projection such that the fovea of the fixating eye has a common visual direction with an area other than the fovea of the deviating eye. The pairing of all retinal elements is similarly changed. It may occur when the eye is used for fixation.
absolute eccentric fixation
eccentric fixation in which the angle of eccentricity = objective angle of deviation
scotoma
loss of vision in part of visual field
accomodation
the ability of the eye to increase its dioptric power (the convexity of the crystalline lens) in order to obtain a clear image of a near object
accommodative convergence
one of the components of the eyes initiated by effort to overcome a blurred retinal image.
AC:A ratio
ratio of accommodative convergence in prism dioptres in relation to one dioptre of acomodation
accomodative facility
measure of how fast clarity is restored following a rapid change of focus
accommodative fatigue
inability to sustain sufficient accom over an extended period of time
accomodative inertia
difficulty in changing the accom state from one fixation distance to the other
accom insufficiency
amplitude of action is lower than would be expected for individuals’ refractive state and age
accom spasm
spasm of ciliary muscle resulting in nr and dis far points of accom becoming closer to eye than expected for patients age associated with psuedomyopia and conv spasm
adjustable suture
sutures can be readjusted within 24 hours
advancement
a surgical technique where the muscle insertion is moved forward from its original insertion thereby strengthening its action
afferent pupil defect
affected pupil does not constrict to direct light stimulation but reacts to consensual due to lesion in optic nerve
agnoist and antagonist
agonist = primary muscle
antagonist= EOM whose action opposes that of contracting muscle
altitudinal defect
involves 2 quadrants of either superior or inferior vf and seen in ischaemic optic neuropathies/ Resect the horizontal midline.
amplitude of accomodation
difference in dioptres between near and far points of accommodation between min and max amount of accommodation
amsler grid
chart used for assessing central visual fields
aniridia
absence of iris
anisocoria
difference in pupil size
anisokonia
difference in size/shape of retinal images of two eyes
anisometropia
difference in RE between two eyes
Anterior Positioning:
A surgical procedure where the insertion of the oblique muscle is moved more anteriorly.
Anticholinesterase
A drug that inhibits or inactivates the action of acetylcholinesterase.
Arcuate Scotoma:
Defect of the retinal fibres causing loss of vision in an arc shape from the optic disc to the nasal side of the fovea either above or below the mid line found in glaucoma.
Argyll Robertson Pupil:
Dissociation of light/near reflex in which the pupil responds normally to near but reacts slowly if at all to light.
In abberent regeneration in 3rd nerve palsy
Asthenopia:
The collective term for various ocular symptoms, including sore and aching eyes; blurred vision and ocular fatigue.
Ataxia
Impaired ability to co-ordinate movement.
mydriasis
pupil dilation
cycloplegia
paralyse the ciliary muscle
Augmented Recession:
Surgical procedure to further weaken a muscle action, ie. recession of tight conjunctiva or very large recession of muscle.
axial legnth
legnth of eyeball e.g. myoped have longer axial legnth
Bell’s Phenomenon:
Elevation of both eyes with divergence when the eyelids are closed.
Benedikt’s syndrome:
Lesion in the region of the red nucleus resulting to an ipsilateral third nerve palsy and contralateral hemitremor.
Bielschowsky Head Tilt Test:
The observation of change in vertical deviation when the head is tilted to the shoulder of the suspected superior oblique weakness. (differentiate between SO palsy and SR weakness in other eye)
Bifoveal Fixation:
Imaging of an object on both foveae at the same time.
Binocular Function:
The ability of the two eyes to co-ordinate binocularly either in free space e.g. using prisms
Binocular Single Vision:
The ability to use both eyes simultaneously so that each eye contributes to a common single perception; may be bifoveal or monofoveal.
Binocular Vision:
The ability to use both eyes simultaneously. This may be with normal or abnormal binocular single vision or with the appreciation of diplopia.
Blind Spot Mechanism (Swann’s Syndrome):
A compensatory mechanism whereby rays of light from the fixation area fall on the optic disc of the deviating eye and thus diplopia is avoided.
Botulinum Toxin (B.T.X.A.):
A neurotoxin produced by the anaerobic bacterium clostridium botulinum; used to paralyse extraocular muscles in the treatment of ocular motility disorders.
Brown’s Syndrome:
An ocular motility defect where the affected eye(s) does not elevate in adduction but has full depression in adduction. It can be congenital or acquired from injury to or defect of the superior oblique tendon or trochlea and has a positive forced duction test result. See `Click’ Brown’s Syndrome.
Cavernous Sinus Syndrome:
A lesion (e.g. tumour) in the cavernous sinus causing paresis of the ocular motor nerves and the first two divisions of the trigeminal nerve
Central Fixation:
The reception of the image of the fixation object by the fovea, the fixation object lying in the principal visual direction. Central fixation may be steady or unsteady.
Central Scotoma:
Only involves fixation. The scotoma is negative and depending on the severity of the lesion, it can be relative or absolute.
Cerebral Palsy:
A condition in which the control of the motor system is affected due to a lesion in the brain resulting from a birth injury or prenatal defect.
Chiasmal Lesion:
Damage to the optic nerve at the decussation above the dorsum sellae causing visual field defects, i.e. bitemporal hemianopias.
Chronic Progressive External Ophthalmoplegia (C.P.E.O.):
Progressive bilateral limitation of ocular motility accompanied by ptosis but usually without diplopia or pupil involvement.
`Click’ Brown’s Syndrome:
A variation of Brown’s Syndrome in which the superior oblique tendon intermittently passes through the trochlea leading to full elevation in adduction, a ‘click’ is felt by the patient when this happens. When the superior oblique tendon does not pass through the trochlea the classic features of Brown’s Syndrome result.
Clinical Governance:
A framework through which NHS organisations are accountable for continuously improving the quality of their services and safe-guarding the high standards of care by creating an environment in which excellence in clinical care will flourish.
Cogan’s Lid Twitch:
Transient eyelid retraction during refixation from down to straight ahead seen in Myasthenia Gravis.
Cogan’s Sign:
A tonic deviation of the eye occurring on forced eyelid closure and associated with lesions in the cerebral hemispheres.
Collier’s (Tucked Lid) Sign:
Unilateral or bilateral lid retraction due to a lesion in the midbrain, e.g. Parinaud’s Syndrome.
Coloboma:
A fissure or gap in the eyeball or one of its parts, e.g. iris.
Colour fields:
Often used for testing macular sensitivity, with red or green targets. The normal red field is between 5 and 7 degrees and the green field between 3 and 5 degrees from the central point of fixation. Conditions in which these fields may be performed include, patients taking hydroxychlorequine for arthritic conditions, compressive thyroid eye disease and optic neuritis.
Compensatory Head Posture:
A position of the head adopted in the interest of comfortable vision, which may consist of:-
a) chin elevation or depression
b) face turn to the right or left
c) head tilt to the right or left shoulder.
These components may exist together or singly.
Confusion
The simultaneous appreciation of two superimposed images due to the stimulation of corresponding retinal points by two different images.
Congenital Saccadic Paresis:
An inability to execute voluntary saccades resulting in the subject thrusting the head to gain fixation and using the vestibulo-ocular reflex to maintain fixation as the head is moved slowly to the midline.
Conjugate Gaze Spasm:
The eyes are directed towards one side dependent on the site and nature of lesion.
Conjunctival Recession:
A surgical procedure to loosen the conjunctiva in order to enhance a weakening of the extraocular muscle.
Constant Esotropia: + Constant Exotropia:
The esotropia is present under all conditions. See also Esotropia with Accommodative Element and Without Accommodative Element + The exotropia is present under all conditions.
Contrast Sensitivity:
The ability of the eye to detect objects of varying contrast which can be tested using sinusoidal gratings of varying spatial frequency and varying luminance intensity.
Controlled Binocular Acuity (CBA):
The maximum visual acuity obtainable while maintaining binocular vision.
Convergence accommodation
Change in accommodation induced by convergence. Best demonstrated in open loop conditions, as in the closed loop situation relative negative accommodation will be used to maintain a clear image.
Convergence Excess Esotropia:
An intermittent esotropia with binocular single vision present at distance fixation but esotropia on accommodation for near fixation.
Convergence Insufficiency (C.I.):
The inability to obtain and/or maintain adequate binocular convergence without undue effort.
Convergence Retraction Nystagmus:
Nystagmus characterized when testing sustained upgaze or the optokinetic drum rotated downwards. Slow downward movements occur but upward movements are replaced by rapid convergent movements that may also retract the globe.
Convergence Spasm:
A condition in which there is excessive convergence. See also Accommodation Spasm.
Corneal Astigmatism:
Refractive error caused by the asymmetrical curvature of the cornea. It may be congenital or acquired from corneal disease.
Cortical Blindness:
A term applied to a severe defect of vision of both eyes as a result of a lesion of the visual cortex. Optic nerve and pupil reflexes may be normal.
Cover Test:
An objective dissociation test, in which each eye is covered in turn by an opaque occluder whilst the patient fixes a specified target in the required position, which detects manifest and/or latent deviations.
Cover Un-Cover Test:
Cover the eye and look at the same eye to see if it moves under the cover
Cover the eye and look at the other eye to see where it moves to (detects the squint in the other eye)
alternate cover = max dev angle
Cranial Nerve Palsy:
a decreased or complete loss of function of one or more cranial nerves. Cranial nerve palsies can be congenital or acquired.
Craniofacial Disorders (dysostosis):
A premature fusion of one or more of the sutures of the skull at a time when the brain is expanding which is caused by a failure in the development of the primitive mesoderm.
Crossed Fixation:
Patient uses right eye to fix in left field and left eye to fix in right field; seen in early onset esotropia, strabismus fixus and sixth nerve palsy. See also Tripartite Fixation.
Crowding Phenomenon (Separation difficulty):
The phenomenon in which a line of letters or symbols of the same size on a test type are identified less easily than single optotypes.
Cyclic Esotropia:
Normal binocular single vision alternates with large angle esotropia in rhythmic cycle.
Cyclic Exotropia:
Normal binocular single vision alternates with large angle exotropia in rhythmic cycle.
Cycloparesis:
Weakness of the ciliary muscle.
Cyclopentolate Hydrochloride (mydrilate):
A short acting mydriatic producing cycloplegia in 30 minutes (parasympatholytic).
Cyclophoria:
On dissociation the occluded eye wheel-rotates. See also incyclophoria; excyclophoria.
Cycloplegia:
Paralysis of the ciliary muscle resulting in loss of accommodation.
Cycloplegic:
A drug, e.g. atropine, which causes paralysis of the ciliary muscle and, therefore, loss of accommodation.
Cycloplegic Occlusion:
The reduction or blurring of vision of one eye by using a cycloplegic drug. e.g. atropine
Cycloplegic Refraction:
Objective refraction often retinoscopy whilst the accommodation of the eyes is paralysed .
Cyclotorsion
Rotation of the eye around its visual axis - see also incyclotorsion; excyclotorsion.
Cyclotropia:
One eye is wheel rotated so that the upper end of its vertical axis is nasal (incyclotropia) or temporal (excyclotropia) assessed objectively using fundus photographs.
Cyclovergence:
Range of incyclo and excyclo motor fusion.
Decreasing Velocity Exponential:
A term used to describe the slow phase in jerk nystagmus which has a decreasing velocity and which characterises latent nystagmus, manifest latent nystagmus and gaze evoked nystagmus.
Delayed Visual Maturation:
A condition where the appearance of the eye is normal, and the child does not respond to visual stimulus at a young age, but visual development occurs later than normal. This is the primary type of DVM, however, some classification systems include cases with an identifiable deficit in the eye or brain which result in slower visual development but may not reach normal levels.
Depression
Rotation of the eye downwards.
Depressor:
A muscle whose action is to turn the eyeball downwards.
Diabetic Ophthalmoplegia/ Ophthalmopathy:
Diabetic ophthalmopathy implicates complications of diabetes mellitus such as diabetic retinopathy, diabetic maculopathy, rubeosis of the iris, secondary glaucoma, complicated cataract, diabetic neuropathy of cerebral nerves supporting ocular muscles, diabetic neuropathy of optic nerves.
Diagnostic Occlusion:
Diagnostic occlusion to disrupt fusion in order to reveal the maximum deviation (30 mins for simulated by fusion in microtropia if d/nr angle increases, opp angle e.g. nr sim by fusion = after occ for 30 mins distance angle increases)
Dilate
To enlarge the pupillary aperture.
Dioptre:
A unit of measurement of the power of a lens equal to the inverse of the focal length in meters. A one dioptre lens brings parallel light in focus at one metre.
Direction of Nystagmus:
Defined by the direction of the fast phase or beat, although the pathological movement is the slow drift off fixation and the fast phase constitute the corrective movements.
Diplopia
The simultaneous appreciation of two images of one object. See also Pathological; Physiological; Homonymous; Heteronymous; Incongruous; Paradoxical
Direction of Nystagmus:
Defined by the direction of the fast phase or beat, although the pathological movement is the slow drift off fixation and the fast phase constitute the corrective movements.
Disjugate (disjunctive):
Movements of the two eyes in which the visual axes do not remain parallel but move in opposite relative directions. See also Convergence, Divergence.
Dislocated Lens:
The lens becomes dislocated into the vitreous or, rarely, into the anterior chamber because of an associated degeneration of the suspensory ligament of the lens.
Disorders of Accommodation:
See Accommodative Fatigue; Inertia; Spasm
Dissociated Nystagmus:
The movements of the two eyes are different.
Dissociated Vertical Deviation (Divergence) D.V.D.:
When the level of illumination received by either eye is reduced sufficiently that eye deviates progressively upwards, but reverts to its original position when the level of illumination returns to normally acceptable levels. It may sometimes be so asymmetrical as to be virtually unilateral and is associated with heterotropia usually of early onset or, rarely, with binocular single vision.
Distance Esotropia:
An intermittent esotropia where binocular single vision is present on near fixation and an esotropia on distance fixation.
Distance Exotropia:
An intermittent exotropia where there is binocular single vision on near fixation and exotropia (intermittent or constant) on distance fixation. See also True or Simulated Distance Exotropia.
Distance Penalisation:
The use of the amblyopic eye for distance by using additional plus lenses in front of the fixing eye.
Divergence:
Simultaneous rotation of the eyes outwards.
Divergence Excess Exotropia:
See Distance Exotropia (divergence excess xop decompensated?)
Divergence Excess Type Exophoria:
Exophoria greater on distance fixation than near fixation.
Divergence Paralysis:
Inability to relax visual axes at distance, resulting in esotropia.
Divergence Weakness Type Esophoria:
Esophoria greater on distance fixation than near fixation.
Doll’s Head Manoeuvre:
A rapid, passive head rotation to elicit an initial proprioceptive contraversion deviation of the eyes followed by a prompt recentring.
Dorsal Midbrain Syndrome:
See Parinaud’s Syndrome
Double Depressor Palsy:
Limitation of downgaze without reference to a particular vertical muscle palsy.
Double Elevator Palsy:
A limitation of up gaze without reference to a specific muscle defect.
Downbeat Nystagmus:
Eyes drift up and beat down again, associated with a lesion in the posterior fossa near the cranio-cervical junction.
Down’s Syndrome:
A congenital abnormality with learning difficulties and characteristic facial features. May have myopia, strabismus and visual acuity problems.
Duane’s Retraction Syndrome:
A congenital condition of limitation of horizontal ocular movement with retraction of the globe and narrowing of the palpebral fissure on adduction.
Duction:
Rotary movement of ONLY one eye from the primary position, i.e. Adduction; Abduction; Supraduction; Infraduction; Incycloduction; Excycloduction. (version = both eyes moving simultaneously)
Infantile Esotropia:
Constant esotropia occurring before 6 months of age. With or without latent nystagmus, manifest latent nystagmus, dissociated vertical divergence, cyclotropia, abnormal head posture, limited ABduction.
Early Onset Esotropia:
Onset: 6 months to 2 years
Characteristics: N=D, Amblyopia common, Poor BSV prognosis, Dev may increase c time, Surgery often needed. check om no lateral incomitance and L + R is same size
Early Onset Nystagmus:
Oscillations in both eyes seen from early infancy of any waveform with increasing exponential slow phase.
Eccentric Fixation:
A uniocular condition in which there is fixation of an object by a point other than the fovea. This point adopts the principal visual direction. The degree of the eccentric fixation is defined by its distance from the fovea in degrees.
Eccentric Viewing:
A uniocular condition in which there is fixation of an object by a retinal point other than the fovea without change in the principal visual direction.
Ecchymosis
A bruise: an effusion of blood under the skin.
Ectopia Lentis:
Partial dislocation of the lens causing myopia and astigmatism.
Ectropion
A condition in which the lower lid margin falls away from the globe.
Electronic Health Record (EHR):
A longitudinal record of a patient’s health and healthcare from birth to death.
Electronic Patient Record (EPR):
Used as a replacement for separate files owned by different organisations and departments such as hospitals, GP’s, community services and laboratories.
Elevation
Rotation of the eye upwards.
Elevator
A muscle whose action is to turn the eyeball upwards.
Emmetropia:
A refractive state of the eye when parallel rays of light are brought to focus on the retina when the eye is at rest (not accommodating).
End Point Nystagmus:
Oscillatory eye movements which occur on extreme lateral gaze, with fast phase towards side of gaze.
Enophthalmos:
Posterior displacement of the eye.
Entropion:
A condition in which the lower lid margin turns in onto the globe.
Epicanthic Folds/Epicanthus
Skin folds between the medial canthi and the nose causing pseudostrabismus.
Epinephrine:
A drug which dilates the pupil (sympathomimetic).
Epiphora
An excessive flow of tears.
Epistaxis:
Bleeding from the nose.
Eserine (Physostigmine):
A drug used to constrict the pupil (anticholinesterase).
Esophoria
On dissociation of the two eyes the occluded eye deviates nasally.
Esotropia:
One or other eye deviates nasally when both eyes are open.
Esotropia Controlled by Refraction:
See Accommodative Esotropia
Esotropia Relating to Fixation Distance:
See Near Esotropia; Distance Esotropia
Esotropia Relating to Time:
See Cyclic Esotropia
Esterman Fields:
A visual field analysis carried out on the Humphrey visual field analyser in order to establish the extent of peripheral fields to meet D.V.L.A. standard.
Evidence Based Practice:
The conscientious explicit and judicious use of current best evidence when making decisions about individual patients.
Excyclophoria:
On dissociation the upper end of the vertical meridian rotates temporally.
Excyclotorsion:
1) Rotation of the eye around the anteroposterior axis so that the upper end of the vertical meridian rotates temporally. 2) A type of diplopia where a horizontal line tips down temporally associated with an incyclodeviation.
Excyclotropia (excyclodeviation):
The eyes are misaligned around the anteroposterior axis so that the disc appears above the macula due to weakness of the incyclorotating muscles [superior oblique, superior rectus].
Executive Bifocal Glasses:
The entire top portion of the lens is dedicated for distance use whilst the bottom portion is for reading. They offer a much wider reading area than other types of bifocal. See also Bifocal Glasses.
Exophoria:
On dissociation of the two eyes the occluded eye deviates temporally .
Exophthalmic Ophthalmoplegia:
A term used to describe protrusion of the eyeball, associated with defective action of certain of the ocular muscles due to thyroid dysfunction.
Exophthalmos:
Protrusion of the eyeball with upper lid retraction.
Exotropia
One or other eye deviates temporally when both eyes are open.
External Ophthalmoplegia:
Paralysis of all the extraocular muscles with the eye assuming the position of rest.
Extra Ocular Muscles (extrinsic):
The six extra ocular muscles that rotate the eyeball - superior rectus; inferior rectus; medial rectus; lateral rectus; superior oblique; inferior oblique.
Eye Strain:
See Asthenopia
Faden:
A surgical procedure where the muscle is stitched to the globe behind the insertion, to further weaken its action in its field of gaze.
False Localisation:
The incorrect uniocular subjective localisation of the fixation object.
False Negative Response:
There is no response despite the presence of previously seen stimuli.
False Positive Response:
A positive response is given despite the absence of stimuli.
Far Sight:
Hypermetropia; long-sighted.
Far Point of Accommodation:
The furthest point at which an object can be seen clearly.
Fascicular Lesion:
A lesion along the cranial nerve after the nucleus but before the nerve leaves the brainstem.
Fells Modification of Harado Ito Procedure:
A strengthening of the superior oblique by moving the anterior portion of the tendon anteriorly on the globe.
Field of Binocular Single Vision (Field of Binocular Fixation):
The extent to which binocular single vision is maintained by movement of the eyes whilst the head is kept still.
Field of Uniocular Fixation:
The extent to which each eye can maintain foveal fixation whilst the head is kept still.
Fixation Disparity:
A phenomenon which occurs in binocular single vision in which the image is seen singly despite a slight under or over convergence of the visual axes, provided the disparate retinal points are within Panum’s area. It generally increases if binocular single vision is under stress and can be demonstrated instrumentally when fusion occurs for identical features of two targets but any dissimilar features are displaced in the direction of the heterophoria.
Forced Duction Test:
A test used to determine the tone of the muscle by attempting to move the eye with forceps in different directions. It is termed positive when there is significant resistance to movement.
Forced Generation Test:
A test to determine the function of a paralysed extra ocular muscle.
Form Deprivation:
A factor causing amblyopia due to an obstacle preventing a clear image at the fovea.
Fourth Nerve Palsy [4th/IV N. Palsy]:
Partial or complete loss of function of the superior oblique muscle.
Foville’s Syndrome:
Horizontal gaze palsy, fifth, seventh and eight nerve palsies, ipsilateral Horner’s syndrome
Frequency of Nystagmus:
The number of oscillations occurring per second.
Fresnel Lenses/Prisms:
Plastic prisms or lenses which can be adhered temporarily to spectacles.
Fully Accommodative Esotropia:
Esotropia in which normal binocular single vision is present for all distances when the hypermetropia is corrected.
Fully Accommodative Esotropia with Microtropia:
See Microtropia with Fully Accommodative Characteristics.
Functional:
1) A deviation which has the ability, at least potentially, for binocular single vision.
2) Patient shows signs or symptoms of a disorder but careful examination fails to reveal any evidence of structural or physiological abnormalities. There may be spiralling fields or improvement in visual acuity with plano lenses.
Functional Assessment:
The assessment of the behaviour of a person with low vision.
Functional Paralysis of Accommodation:
Inability to accommodate due to disordered states of mind or suffering from neurosis.
