350 likes | 686 Views
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
E N D
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
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(accommodation range)
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 RAF Near Point rule(convergence)
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) • DV6Δ ESO to 8Δ EXO & 1Δ Hyper • NV6Δ 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
Exophoria • Eye turns out when covered • Realigns when uncovered
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 to • point at are the measurement • of the deviation
Confrontation Fingers Neurological pins Perimetry Static Kinetic Macular field Amsler grid Visual field
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.