Orthoptics + Orbital disease Flashcards
What is binocular vision and what 3 things is it based on?
Brains ability to perceive a single image from each eye
Based on:
Simultaneous perception (good visual acuity in both)
Depth perception
Fusion (alignment of visual axes)
Where are the different categories of squint?
Manifest (pathological) - Concomitant/Incomitant
Latent (physiological) - compensated/decompensated
In the cover + alternate cover tests what is seen in convergent + divergent?
Convergent (esotropia) - eye moves away from nose after uncovering
Divergent (exotropia) - eye moves towards nose from uncovering
In what cases in the cover tests may fixation not be able to occur? (2)
What sign use instead?
V poor visual acuity (can't fixate anyway) Muscle paralysis (cannot fully take up fixation)
Use corneal reflections as guide
Who are concomitant squints mostly seen in?
What conditions are they associated with?
Children (eso*/exo)
Convergents: Hypermetropia (child wears glasses) + Amblyopia
What is amblyopia?
List 3 causes
Reduced acuity from failure of development of visual pathways (→ lazy eye)
Causes:
Stimulus deprivation e.g. severe ptosis, congenital cataracts (lack of sharp image on macula at critical stage of devel)
Strabismic (squint) (uncorrected myo/hypermetropia - brain suppresses deviated image)
Anisometropic (diff refractive powers + brain favours better eye)
When should management of a squint be started?
What is the management? (OOO)
As soon as noticed (>7yrs too late)
Optical: correct refractive errors
Orthoptic: patch on good eye
Operation: resection/recession of rectus muscles (cosmetic) + Botox
What is seen in a cover test of a manifest squint?
When normal eye covered → bad eye corrects itself (takes up fixation) (+good eye deviates)
When good eye uncovered → bad eye deviates again (+ good eye to normal)
What is seen in an alternate cover test in a latent squint?
If eye moves (to take up fixation) when uncovered → latent squint
NB latent squint will have in both eyes
What measures of visual acuity can be used in children?
Preferential looks (shows have some form of sight)
Cardiff cards / Kays pictures
LogMAR (reading age)
What is an incomitant squint? List the causes (5)
Due to CN3/4/6 palsy/paralysis
Microvascular (BP/DM)
Nerve compression (direct - aneurysm; indirect - space occupying lesion raising ICP)
Head injury (esp CN4)
Mechanical (thyroid; orbit inflamm; orbit trauma)
Idiopathic
What symptoms may be seen in orbital disease? (3)
What signs may be seen? (8)
Diplopia
Pain/discomfort
Reduced vision
Soft tissue involvement Exophthalmos (proptosis) Pseudoproptosis (high myopia/contralat endophthalmos) Endophthalmos Ophthalmoplegia Visual dysfunction Dynamic changes (pulsation) Fundus changes
What are some causes of soft tissue involvement in orbital disease? (3)
Lid/periorbital oedema
Ptosis
Conjunctival swelling
What are some causes of proptosis/pseudo? (TIT)
Thyroid eye disease
Tumour
Inflamm/infection
What are some causes of endophthalmos? (3)
Small globe
Structural abn (e.g. blow out)
Atrophy of orbit contents (irradiation/scleroderma)
What are some causes of ophthalmoplegia? (5)
Tumour Infection (cellulitis) Trauma (blow out) Restrictive myopathy Ocular motor nn lesions
What kinds of dynamic changes may be seen in orbital disease (2)
And give examples of conditions where these changes might arise (2/3 each)
Venous pressure increase: thyroid eye, vascular probs
Pulsation: AV communication, orbital floor defects, CSF pulsation
What kinds of fundus changes may be seen in orbital disease (3)
Retinal/vascular changes
Disc changes
Choroidal folds
What ocular manifestations are seen in thyroid eye disease? (2 main + 2 rare)
Soft tissue involvement (eyelid/periorbital oedema)
Exophthalmos (1/3rd)
Diplopia (restrictive myopathy/oedema/fibrosis)
Optic nn compression / neuropathy (open angle glaucoma)
What can be given to patients with permanent diplopia?
Prisms (alleviate symptoms)
What are some symptoms (2) and signs (4) of orbital cellulitis?
Severe malaise + fever
Pain
Painful ophthalmoplegia
Severe orbital oedema (+redness)
Ptosis
Optic nn dysfunction (advanced)
What are some complications of periorbital oedema (2)
Optic neuropathy Abscess formation (→ cranial if severe)
What is idiopathic orbital inflammatory disease?
How does it usually present? (3)
Signs (4)
Any non-neoplastic / non-infectious orbital lesion (Dx of exclusion)
20-50yrs unilateral abrupt onset
Unilateral proptosis
Periorbital swelling
Ophthalmoplegia
Chemosis (irritation)
What are the main vascular orbital disorders? (2)
Orbital varices
Carotid-canervous fistulas
