Transcript VISUAL ASSESSMENT OF AVIATORS

Assessment of Aviators
Ophthalmic history
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Current eye disease
Past ophthalmic history
Past medical history
Family history (esp eye disease)
Drugs and medications
Allergies
Visual acuity
• Contact lenses removed 2 weeks beforehand
• Current spectacle correction
• Recent opticians report with refraction
Distant visual acuity
• Backlit Snellen chart at 6 meters
• Monocular
– Do not press on occluded eye
• Without then with correction then pinhole
• No cheating
– Memorising
– Not covering better eye
– Eye lids open normally
Refraction
• If Sn VA < 6/6 and improves with PH
– Suggests refractive error in absence of ocular
disease
• Optician will perform this and give report
• Different refractive limits for different air
forces
• UK pilot: Plano to +1.75 Sphere (RN/AAC
-0.75 to +1.75) and +0.75 Cyl
Near visual acuity
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Near acuity card
Good illumination
33 cm
Monocular
With and without correction
N4 - N48
Aircrew need to be N5 or better at selection
RAF Near Point rule
(accommodation range)
• N test type
• With glasses
– Reading correction
• Monocular
– ‘Custom’ (right)
– ‘every’ (left)
• N5 at 50cm - 30cm
(Age 17-20 9D, Age
20-25 7D)
– Endpoint type blurs
• Binocular
– incongruity if
convergence weakness
(binoc<monoc)
• CAA limits
– N5 30-50cm
– N8 at 1m for some
RAF Near Point rule
(convergence)
• Line and dot
• Point of doubling
• Objective convergence
recorded if no doubling
noted
– not blurring
• Subjective convergence • Convergence
insufficiency
• Objective convergence
• When one eye hesitates stops
or diverges
• To 10 cm or better
– symptomless/aesthenopia
– ageing
– responds to orthoptic
exercises
Stereopsis
• 120 degrees of arc for RAF aircrew
• Titmus
– Three-dimensional polaroid vectograph
– Includes Wirt’s fly, circles and animals
• TNO
– Random dot test (used by RAF)
• Frisby
– Hidden circle painted on back of plastic plate
TNO test
(Toatepast Natuurwetenschap Ondersoek)
Left: cross is seen with and
without red/green spectacles
Right: 4 hidden shapes seen with
without red/green spectacles if
stereopsis present
Colour perception
• Ishihara pseudoisochromic (PIP) test
– Colour confusion (R/G)
• Holmes-Wright lantern
– Functional colour discrimination (R/G)
• Colour Assessment and Diagnosis test
(CAD) - New
CP 1 & 2
• CP 1: The correct recognition of coloured lights
shown through the paired apertures on the
Holmes-Wright lantern at LOW BRIGHTNESS at
6 metres (20 feet) distance in complete darkness
• CP 2: The correct recognition of 13 out of the first
15 plates of the Ishihara Test (24-Plate abridged
Edition 1969) shown in random sequence at a
distance of 75 cm under standard fluorescent
lighting supplied by an artificial daylight
fluorescent lamp (British Standard 950: 1967)
CP 3, 4 & 5
• CP 3: The correct recognition of coloured lights
shown through the paired apertures on the
Holmes-Wright lantern at HIGH BRIGHTNESS
at 6 metres (20 feet) distance in complete darkness
• CP 4: The correct recognition of colours used in
relevant trade situations, and assessed by simple
tests with coloured wires, resistors, stationery tabs
etc.
• Personnel who fail to reach the minimum standard
of colour perception are to be graded CP5 - failed
trade test and colour expanses.
Testing for CP
• Ishihara plates are used as a screening for
all entries
• Candidates who pass the Ishihara test are
graded CP2 and require no further testing
except for those whose critical visual task
requires a categorisation of CP1
• Candidates who fail the Ishihara test are
further tested for CP3 or CP4 according to
requirement
Ocular muscle balance
• Tropia
• Phoria (Pilot standard at selection)
& 1Δ Hyper
– NV 6Δ ESO to 16Δ EXO & 1Δ Hyper
– DV 6Δ ESO to 8Δ EXO
Cover test
• Manifest strabismus
– Cover test
• Latent strabismus
– Alternate cover test
EsoPHoria
• Covered eye turns in
• Can be seen to realign
when uncovered
Esophoria
Exophoria
• Eye turns out when
covered
• Realigns when
uncovered
Exophoria
EsoTropia
• Eye turned in all the
time
• Realigns when straight
eye covered
Exotropia
• Eye turned out all the
time
• Realigns when straight
eye covered
Maddox Rod
• Dissociating test that will reveal and
measure (but not distinguish between) a
phoria or a tropia.
• A dissociating test is a test that presents
dissimilar objects for each eye to view, so
that the images cannot be fused.
• The MR test is most commonly used only to
measure phorias (i.e. after a cover test)
Maddox rod
• Red lens to right
• Assesses phoria
• eXo crossed image
– (spot to right of line)
No horizontal phoria
Exophoria
• Near Maddox rod
– 33cm
– Pen torch
Esophoria
Maddox Wing
• An old-fashioned but simple and fast way of
seeing how close or far the eyes are away
from alignment, at near, in the absence of
any attempt at fusion.
• It does not differentiate between
heterophorias or heterotropias.
Maddox wing
• Eyes dissociated by septa
• RE sees the arrows
• LE sees the scales (horizontal, vertical
& torsional)
• The numbers the arrows appear to
point at are the measurement
of the deviation
Visual field
• Confrontation
– Fingers
– Neurological pins
• Perimetry
– Static
– Kinetic
• Macular field
– Amsler grid
Ophthalmoscopy
• Direct
– Magnified view of central 10 degrees
– Disc and macula well visualised
– Affected by refractive error
• Indirect
– Allows examination of retinal periphery
– Indentation
RAF Aircrew Visual Selection
Standards Summary
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(D = dioptres, visual acuity by Snellen Test Type, near acuity by Standard
Near Vision Type, colour vision by Ishihara Pseudo-isochromatic (24) Plate
Test and Holmes-Wright Lantern test)
JAR Class 2 Visual Standards
• The initial refractive error (correction)
limit is +5/-6 dioptres.
• There is no myopic limit for
revalidation/renewal.
• The astigmatism and anisometropia
initial limits are 2 dioptres, but there are
no limits for revalidation/renewal.
NOTE: contact lenses must be worn if the
anisometropia exceeds 3 dioptres.
JAR class 2
• The correction limits for the initial Class
2 examination are +5/-8 dioptres.
• There are no myopic limits for
revalidation/renewal.
• The initial limits for astigmatism and
anisometropia are 3 dioptres, but may go
beyond this for revalidation/renewal.
JAR Class 1 Comprehensive
Eye Examinations
Prescription
Frequency of Comprehensive
Examination
+3 to +5 dioptres
5 yearly
-3 to -6 dioptres
5 yearly
-6 dioptres or more
2 yearly
3 dioptres of astigmatism or more
2 yearly
3 dioptres of anisometropia or more
2 yearly