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AVIATION
OPHTHALMOLOGY 2
MEDICAL FACTORS
Wg Cdr Malcolm Woodcock
RAF Ophthalmology
Centre for Defence Medicine
University Hospital Birmingham, UK
Ocular Adenexae
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Blepheritis
Chalazion
Epiphora
Orbital Blowout fracture
External eye disease
• Blepharitis
– Lid hygiene
– Topical/systemic
tetracycline
• Dry eye
(keratoconjunctivitis
sicca)
– Ocular lubricants
• Ocular allergic disease
– Mast cell stabilisation
(Na Chromoglycate)
– Topical steroids
– Systemic
antihistamines
• A bar to flight training
Eyelid disease
Epiphora (Watery Eye)
• Reflex – corneal or conjunctival irritation
• Obstructive – mechanical obstruction of
nasolacrimal drainage system
• Functional – Failure of lacrimal pump
system through lack of tone in lower lid
(ectropion, VII nerve palsy)
Blowout Fracture
Patient is looking up. Loss
of infraorbital sensation
and subcutaneous crepitus
are useful signs.
Opacification of
maxillary sinus with
entrapment of inferior
rectus / its attachments.
Anterior Segment
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Episcleritis
Recurrent Erosion Syndrome
Keratoconjunctivitis sicca
Ketatitis (microbial, adenoviral, herpetic)
Keratoconnus
Uveitis
Ocular hypertension and glaucoma
Cataract
Bacterial keratitis
• Serious ocular infection
• Requires admission and expert management
• Treatment
– Corneal scrape and culture
– Topical antibiotics
• Visual result depends on amount and
position of retinal scarring
Viral Keratitis
• HSV keratitis
• Dendritic ulcer
– Topical Aciclovir
• Metherpetic disease
– 20-25% (Disciform
keratitis)
– Top Aciclovir/steroids
– Oral Aciclovir 1yr (not
aircrew despite RCT)
• Adenoviral keratitis
– Follicular
keratoconjunctivitis
– Highly infectious
– Corneal stromal
opacities
– Can affect optic axis
– May require topical
steroids
Keratoconus
• Corneal ectactic disease
• Conical cornea
• Management
– Glasses
– Hard contact lenses
– Penetrating keratoplasty
Keratoconus in aircrew
• Often develops in teens to 20s
• ‘Forme fruste’ of keratoconus may be
present in aircrew applicants
– No test for progression
• Piggy-back CL hard centre with soft
surround
– Possible use in fast-jet aircrew
– Not tested yet
PK for keratoconus
Penetrating keratoplasty
• Visual rehabilitation uncertain
– Astigmatism
– Rejection
– Graft failure
• May require permanent topical medication
• Aircrew unfit agile aircaft / ejection
Uveitis
• Inflammation of eye
– Idiopathic
– Infectious
– Systemic disease
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Anterior
Intermediate
Posterior
Pan-uveitis
• Treatment
– Topical / systemic
• Anterior uveitis
– often controlled with
topical steroids
– Flying category usually
preserved with
limitations
• Systemic
immunosuppression
Uveitis
Glaucoma
• POAG
– Syndrome of
characteristic optic
neuropathy associated
with a raised IOP
– Familial
• ACG
– Acute glaucoma
associated with
narrow iridocorneal
angles
• Ocular hypertension
– Not galucoma
– risk of POAG
– Retinal vascular
occlusion
POAG
• Visual field loss
– Monitored
– Flying category depends on this
• Treatment
– Medical (Beta Blockers safe in aircrew)
– Surgical (ALT / Trabeculectomy)
Cataract
• Lens opacity
– Congenital
– Acquired
• Treat if symptomatic
• In aircrew
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Usually congenital
Trauma / Surgery
Inflammation (Fuchs)
Metabolic (DM)
Drugs (Steroids)
• Small inscision surg
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Phacoemulsification
Micronuclear
Rapid rehabilitation
Tiny corneal scar
• IOL
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PMA / Acrylic / Si
Same SG as aqueous
Ejection / vibration
should be safe
Phacoemulsification in aircrew
• 5 Aircrew operated on
for LO
– Traumatic 3
– Inflammatory 1
– Congenital 1
• All achieved 6/6 VA
• All fit flying
– 2 Fast Jet
– 2 Helicopter
– 1 Transport
Amblyopia
• ‘Where the Doctor and
patient sees nothing’
• Central suppression of
image to avoid
diplopia
• Visual maturation by
age 7
• Associated
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Strabismus
Anisometropia
Visual deprivation
Refractive
• Treatment with
patching as child
• Untreatable as adult
– Important if good eye
lost
Strabismus
• Concomitant
– Childhood
• A bar to aircrew entry unless
– Alternate with good vision on each side
– Microtropia (test stereopsis)
• Incomitant
– Extraocular muscle palsy
– Often diplopia (prisms / surgery)
Monocular aircrew
• Reduced stereopsis
• Reduced field of
vision
– Blind spot
• USA FAA
– No difference in
accident rate between
uniocular and
binocular pilots
• Usually restricted to
fly as or with qualified
co-pilot
Corneal disease
• Keratoconus
• Keratitis
– Viral
– Bacterial
• Corneal grafts
Micro-detonator cord Splatter
(MDC)
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Occurs during ejection
May cause skin tattooing
Corneal burns possible
Ophthalmic examination if ocular pain or
reduced VA
Harrier
Ejection
Vitreoretinal Conditions
• Floaters, holes and detachments
• Central Serous retinopathy
• Retinovascular disease
Vitreoretinal disease
• Posterior vitreous detachment
• Retinal detachment (1:10,000)
– External repair (Cryopexy/scleral buckle)
– Internal repair
(Vitrectomy/laser/cryopexy/internal
tamponade)
– Intraocular tamponade agents
Posterior vitreous detachment
(PVD)
• Separation of vitreous gel from retina
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Flashes and floaters (Weis ring)
Abnormal VR adhesion (haemorrhage, tears)
65% by 65yrs
Earlier if Myopic
• If acute symptomatic 10% risk retinal tear
– Indirect ophthalmoscopy with indentation
– Laser retinopexy if necessary
Symptomatic floater in flyer!
• Navigator 36 yo emmetropic (LVA 6/5)
– 6 month history left floater
– Left PVD, prominent Weiss ring
– Felt unsafe to fly as kept on thinking aircraft
closing in periphery
– Left vitrectomy (uncomplicated)
– Kept full flying category
– No problems at 1 year (Minimal myopic shift)
Complications of vitrectomy
• Entry site iatrogenic retinal breaks
– 2-4% in simple vitrectomy
– Risk of retinal detachment
• Index myopia and cataract formation
– Nuclear sclerosis accelerated in all cases
– 75% cataract extraction by 3 years if gas used
Complications of scleral explants
• Myopia
– Especially if encirclement
• Astigmatism
• Extraocular muscle damage
– Diplopia
• Suture complications
– Retinal perforation
– Extrusion
Gas intraocular tamponade
• Posturing required for 1-2 weeks
• Gases
– Air 2 days
– SF6 2 weeks
– C3F8 2 months
• No sight until bubble above optical axis
• Boyles law expansion of bubble if
atmospheric pressure decreases
– Decompression danger with >10% gas in eye
Si oil intraocular tamponade
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Permanent tamponade
Non-expansile
No immediate visual loss
Less posturing
Hypermetropic shift (+6 dioptres)
Less IOP regulation
– increased effects of G forces
Factors affecting fitness to fly
• Visual acuity (Macula on/off)
• Visual field
– Variable effects
• Distortion
– ERM
– Retinal translocation
• Refraction
• Diplopia
Case of RD in Chinook pilot
• 45 y.o. pilot
• Crash 1985
– BK amputation left leg
– Facial trauma
• Routine eye test left visual field defect
• VAL 6/6
Retinal detachment
Before
After
Outcome
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Visual field became full
VAL remained at 6/6
Fit full flying duties
Must have at least 2 legs and 3 eyes in the
cockpit
Retinal degeneration
• Congenital / acquired
• Age related maculopathy
– Dry /exudative
– Macular drusen common
– Commonest cause of blindness in UK
• Hereditary retinal dystrophy
– End stage often macular degeneration
Macular degeneration
Centroserous Retinopathy
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Localised serous chorioretinal detachment
Unknown aetiology
Early mid-aged males affected
VA slightly reduced (hypermetropia)
Diagnosis confirmed on FFA
Spontaeneous resolution the rule
– Hastened by laser
– Slight residual decrease in VA
Amaurosis fugax
• Transient uniocular loss of vision <10 mins
• Embolic
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Carotid artery
Cardiac
Hyperviscosity states
Cranial arteritis
• Flying category depends on treatment of
underlying disease
Central Retinal Vein Occlusion
• Sudden painless visual impairment
• Disc oedema and scattered retinal haems
• Risk factors: Age, hypertension, smoking,
obesity, blood dyscrasias
• Seen in a subset of younger patients
• Poorer prognosis if it becomes ischaemic
Neurophthalmic disease
• Optic neuritis
– Reduced VA (6/186/60)
– Central scotoma
– Impaired colour vision
– Ocular pain
– 75% develop MS
– 70% recover 6/6 in 8
weeks
• Optic disc drusen
– Incidental finding
– Visual field defects
• Nystagmus
– Physiological
– Congenital
– Acquired (always
needs further
investigation)
Optic nerve atrophy and drusen
Laser eye injury
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Ocular hazard of modern warfare
Increasing incidence of laser incidents
Dazzle
Glare
Retinal damage
Fright!!
Laser guided bomb
Wg Cdr Malcolm Woodcock
Department of Ophthalmology
Worcestershire Royal Hospital
Tel: 07891 655845
[email protected]
Contact details
• Wg Cdr Robert A.H. Scott
– RAF Consultant Adviser in Ophthalmology
– Centre for Defence Medicine, Selly Oak
Hospital, Raddlebarn Rd, B’ham B29 6JD
– 0121 627 8535 (Sec) / 8922 (Fax)
– [email protected]