Assessment of Aviators
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Assessment of Aviators
Ophthalmic history
• 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
• 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
– not blurring
• Subjective convergence • Objective convergence
• When one eye hesitates stops or diverges
• To 10 cm or better
• Objective convergence recorded if no doubling noted
• Convergence insufficiency– 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)
– DV 6Δ ESO to 8Δ EXO & 1Δ Hyper
– NV 6Δ ESO to 16Δ EXO & 1Δ Hyper
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)
• Near Maddox rod– 33cm– Pen torch
No horizontal phoria
Exophoria
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 topoint at are the measurementof 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
• (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