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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 • 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 • (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