Fields, Reflexes + Acuity Flashcards
Describe the neuronal pathway in the light reflex
Where is the afferent/efferent pathway to/from?
Retinal ganglion cells (RGC)
→ Pre-tactile nucleus (PTN)
→ Edinger-Westphal nucleus (EWN) (same+ contralat side)
→ Inferior division of CN3)
Aff: RGC → EWN
Eff: EWN → Inf Div 3
What is seen in an afferent pupillary defect (APD)
+ where does the pathology lie?
No consensual / direct response (constriction) to light
Pathology in optic nn (or a large retinal lesion)
What is seen in a relative efferent pupillary defect (RAPD)
Reduced light/consensual response
+
Pupil dilates on swinging eye test (bilat dilation when shine on bad eye)
What actions do nerves within the ciliary ganglion do? (2)
What does the long ciliary nerve do? + where does it originate from
Pupil constriction (sphincter pupillae) Accommodation (ciliary muscle)
Pupil dilation
From Opthalmic branch of trigeminal (V1)
What is Horner’s syndrome
List some features (4)
List some causes (4)
Lesion affecting sympathetic supply to eyes
Partial ptosis (on affected side) Miosis (pupil constriction) Enopthalmos, Anhidrosis
Thyroidectomy/neck surgery/trauma
Thyroid carcinoma, Goitre
Pancoast tumour
What are the features of Argyll-Robertson pupils (2)
What are they caused by? (2)
Small pupils
Light-near dissociation
Mainly caused by tertiary (neuro) syphilis
Affects midbrain + can present with uveitis
Also caused by diabetic retinopathy (less common)
What is light-near dissociation and what pathology does it indicate?
+ve accomodation reflex but -ve light reflex
= brainstem pathology
What is seen in an Adies pupil?
What is it caused by?
Unilateral dilated pupil in otherwise healthy (usually young women)
Poor/slow light/near reflexes
Due to viral/bacterial infection of ciliary ganglion
What effects on the visual field are seen in lesions of:
- L/R optic nn
- Optic chiasm
- L/R optic tract (at chiasm)
- L/R lateral geniculate nucleus (tract after chiasm)
- L/R monocular vision loss
- Bitemporal hemianopia (nasal fibres of temporal fields)
- L/R nasal hemianopia
- R/L Homonymous hemianopia (of contralat nasal field)
What effects on the visual field are seen in lesions of:
- L/R optic radiation: a) parietal b) temporal
- L/R primary visual cortex
- a) parietal = R/L inferior quadrantopia
b) temporal = R/L superior quadrantanopia - Homonymous hemianopia (with macular sparing)
What are the main causes of visual impairment in children? (3)
+ other less common causes (3)
Congenital cataracts
Buphthalmos (congenital glaucoma)
Myopia
Optic atrophy
Albinism
Retinopathy of immaturity
What are the main causes of visual impairment in adults (6)
Diabetic retinopathy Macular degeneration Myopia Uveitis Corneal dystrophies Retinitis pigmentosa
What are the main causes of visual impairment in elderly? (4)
Age related macular degeneration
Glaucoma
Inoperable cataracts
Diabetic retinopathy/maculopathies
What proportion of visual impairment is seen in: children, adults + elderly
Children (5%)
Adults (25%)
Elderly (75%)
What visual assessments can be done for visual impairment? (6)
Record distance vision aided/unaided Retinoscopy (w. retinoscope) Subjective refraction (pts opinion on lens power) Near vision assessment Unit magnification Visual acuity (LogMAR + Snellen)
