The following are the requirements for the medical certification of aircrew, including guidance material issued by the UK CAA Medical Department in relation to the visual system
Refer to Eye Conditions for certificatory guidance on common eye conditions.
Refer to Isotretinoin policy for guidance, where appropriate.
Refer to guidance on Retinal Arterial Disorders and Retinal Vein Occlusion.
Refer to Aviation laser exposure self-assessment (Alesa) (PDF)Medical reports - Ophthalmic (PDF)
(4) The possible cumulative effect of more than one eye condition should be evaluated by an ophthalmologist.
Refer to Ophthalmology Examination report (PDF) and guidance on completion. A routine eye examination that forms part of all revalidation and renewal examinations shall include: history; visual acuity, near and distant vision (uncorrected and with best optical correction if needed), examination of the external eye, anatomy, media, fundoscopy and further examination on clinical indication.For conditions where deterioration in visual function may pose a significant risk to flight safety, then a Medical Assessor should impose a RXO limitation
Eye specialist refers to an ophthalmologist or an optometrist qualified in optometry and trained to recognise pathological conditions.
(a) Eye examination
(1) At each aero-medical revalidation examination an assessment of the visual fitness of the applicant should be undertaken and the eyes should be examined with regard to possible pathology. Conditions which indicate further ophthalmological examination include but are not limited to a substantial decrease in the uncorrected visual acuity, any decrease in best corrected visual acuity and/or the occurrence of eye disease, eye injury, or eye surgery.
(i) history;(ii) visual acuities - near, intermediate and distant vision (uncorrected and with best optical correction if needed);(iii) examination of the external eye, anatomy, media and fundoscopy;(iv) ocular motility; (v) binocular vision;(vi) visual fields;(vii) colour vision;(viii) further examination on clinical indication.(3) At the initial assessment the applicant should submit a copy of the recent spectacle prescription if visual correction is required to meet the visual requirements.
(iii) At revalidation and renewal examinations, notwithstanding point (b)(1)(i), applicants with acquired substandard vision in one eye or acquired monocularity shall be referred to the medical assessor of the licensing authority and may be assessed as fit subject to a satisfactory ophthalmological evaluation.
Local ophthalmologist reports and an assessment with a consultant aviation ophthalmologist will be required before a fit assessment can be made.Class 1 applicants with substandard vision should be referred to a Medical Assessor for further advice about the type of Medical Flight Test to be undertaken.
Class 2 - UK CAA Sub-standard vision (PDF) flow chart Medical Flight Test (PDF) - Substandard Vision in one Eye
(2) Applicants should wear contact lenses if:(i) hypermetropia exceeds +5.0 dioptres;(ii) anisometropia exceeds 3.0 dioptres
A CCL limitation - correction by means of contact lenses - should be applied in cases of keratoconus where the visual requirements are met only with contact lenses, rather than spectacles.
Refer to Eye Surgery for guidance following collagen cross-linking for keratoconus. Medical reports - Ophthalmic (PDF)
Refer to Visual fields and binocular function policy for guidance on normal fields of vision and binocular function.
Refer to Eye Surgery for guidance
Medical reports - Ophthalmic (PDF)
Refer to Eye Surgery for guidance
Medical reports - Ophthalmic (PDF)
(f) Visual correction
Correcting lenses should permit the licence holder to meet the visual requirements at all distances.
Class 1 & 2 - Correcting lenses
Refer to Guidance on presbyopic correction
Refer to guidance for the use of Contact lenses
Refer to Guidance on pilot spectacle frame and lens choice
Refer to Guidance on use of sunglasses by pilots
(c) Those failing the Ishihara test should be examined by:
(1) Anomaloscopy (Nagel or equivalent). This test is considered passed if the colour match shows normal trichromacy, i.e. a matching midpoint of 38-42 scale units and the matching range is 4 scale units or less; or if the anomalous quotient is acceptable; or by (2) Colour Assessment and Diagnosis (CAD) Test. This is considered passed if the threshold is less than 6 SU for deutan deficiency, or less than 12 SU for protan deficiency. A threshold greater than 2SU for tritan deficiency indicates an acquired cause which should be investigated.
The UK CAA does not accept lantern testing as evidence of being colour safe.
Anomaloscopy (Nagel or equivalent) may be considered provided the full protocol used for testing is enclosed with the result. This test is only considered passed if the colour match shows normal trichromacy, i.e. a matching midpoint of 38-42 scale units and the matching range is 4 scale units or less. Tests that have not been performed in the UK must have been conducted by an Aeromedical Centre in another Competent Authority. Applicants failing the Anomaloscope test may undergo the CAD test. All applicants in the UK for advanced colour vision testing should be tested using the CAD test conducted under CAA protocols (available on request).
The CAD test will only pass as colour safe, those individuals who perform as well as individuals with colour vision in the normal range on the most difficult aviation colour vision tasks. See CAA papers:
• CAA Paper 2006/04 Part 1 Minimum Colour Vision Requirements for Flight Crew: The Use of Colour Signals and the Assessment of Colour Vision Requirements in Aviation• CAA Paper 2006/04 Part 2 Minimum Colour Vision requirements for Professional Flight Crew: Task Analysis• CAA Paper 2009/04 Minimum Colour Vision Requirements for Professional Flight Crew: Recommendations for new colour vision standards.
For further additional reading, see CAP 1429 Analysis of European colour vision certification requirements for air traffic control officers.
There is a wide diversity of colour testing methods employed and standards used for the assessment of flight crew minimum colour vision requirements throughout the world, including amongst European States.
Colour vision requirements and assessment of 'colour safety' based on Ishihara (IH) tests have the following problems:
Colour vision requirements and assessment of 'colour safety' based on lantern tests have the following problems.
Colour vision requirements and assessment of 'colour safety' based on anomaloscope tests (i.e., dichromatic, RG colour matching tests) have the following problems.
The Colour Assessment and Diagnosis (CAD) Test provides an accurate and reproducible assessment of an applicant's class of colour vision and severity of RG and YB colour vison loss. The latter can be used to set Pass / Fail limits that do not discriminate against applicants with mild to moderate RG colour deficiency who have been shown to carry out the safety-critical, colour related tasks as well as normal trichromats.
The CAD test cannot be learnt and there are no cues the applicant could use to pass it. The results reflect only the RG and the YB sensitivity of the eye. The results are expressed in Standard Normal CAD units (i.e., RG = 1.0 and YB = 1.0) which represent the median RG and YB colour signal strengths for young, healthy normal trichromats. A threshold of 6 units means that the applicant requires 6 times greater colour signal strength than the standard CAD observer.
Upper limits that describe the binocular and the monocular performance of normal trichromats as a function of age (~ 8 to 85 yrs of age) are incorporated in the test. These are used to screen reliably for normal trichromatic colour vision and also make it possible to detect the presence of retinal or / and systemic diseases that affect vision. The CAD test can also detect acquired deficiencies, even when acquired loss is present in applicants with congenital RG colour deficiency.
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