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Toronto Notes 2019 Ocular Emergencies Diplopia (Double Vision)
Table 3. Common Causes of Diplopia
Binocular Diplopia Monocular Diplopia Definition
Occurs with both eyes open, eliminated with occlusion of either Occurs with one eye open, remains with occlusion of unaffected
Ophthalmology OP5
eye
Congenital: strabismus syndromes
Ocular motor nerve dysfunction: III, IV, VI Nerve Palsy
Neuromuscular junction disease: myasthenia gravis, botulism
Mechanical process: muscle restriction/entrapment, thyroid ophthalmopathy
eye
Supranuclear Causes: INO (multiple sclerosis, brainstem infarct)
Causes
Optical factors: refractive error/astigmatism
Mechanical process: dislocated lens, postoperative sequelae (cataract surgery, peripheral laser iridotomy)
Other: strands of mucus in tear film (keratoconus)
Ocular Problems in the Contact Lens Wearer
• solutionhypersensitivity
• tightlenssyndrome
• cornealabrasion
• giantpapillaryconjunctivitis/contactlensallergy
Ocular Emergencies
• SPKfromdryeyes
• limbalstemcelldeficiency
• cornealneovascularization
• sterilecornealinfiltrates(immunologic)
• infectedulcers(Pseudomonas,Acanthamoeba)
Example 1
VSC
20/40 –1
20/80 +2g20/25 PH
These require urgent ophthalmology consultation for management
Sight-Threatening
• lid/globelacerations
• chemicalburn
• cornealulcer
• gonococcalconjunctivitis • acuteiritis
• acuteglaucoma
• CRAO
• intraocularforeignbody
• RD(especiallywhenmaculathreatened) • endophthalmitis
• GCA
Life-Threatening
• proptosis(ruleoutcavernoussinusfistulaorthrombosis)
• CNIIIpalsywithdilatedpupil(intracranialaneurysmorexternallycompressiveneoplasticlesion) • papilledema(elevatedincreasedintracranialpressureworkup)
• orbitalcellulitis
• leukocoria:whitereflex(absentredreflex,mustruleoutretinoblastoma)
The Ocular Examination
Visual Acuity – Distance
• SnellenAcuity = testingdistance(usually20ftor6m) smallest line patient can read on the chart
■ e.g. 20/40 = what the patient can see at 20 feet (numerator), what a “normal” person can see at 40 feet (denominator)
• distancevisualacuityshouldbetestedwithdistanceglassesoninordertoobtainbestcorrectedvisual acuity
• testinghierarchyforlowvision:Snellenacuity(20/x)→countingfingersatagivendistance(CF)→hand motion (HM) → light perception with projection (LP with projection) → light perception (LP) → no light perception (NLP)
Example 2
VCC CF 3' HM
Note: RIGHT EYE visual acuity always listed on top.
V Vision
SC Without correction CC With correction
20/40 -1
20/80+2
All except one letter of 20/40
All of 20/80 plus two letters of 20/70
PH Visual acuity with pinhole correction
CF Counting fingers HM Hand motion
Figure 5. Ophthalmology nomenclature for visual acuity
OD = oculus dexter = right eye OS = oculus sinister = left eye OU = oculus uterque = both eyes
Snellen visual acuity of 20/20 equates to “normal” vision
Normal Infant and Child Visual Acuity
• 6-12 mo: 20/120 • 1-2 yr: 20/80
• 2-4 yr: 20/20