assessment of aviators

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