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location of controls are found in many new aircraft but there is still room for improvement. Good visual function
and adequate colour perception are necessary for proper use of the wide variety of maps, dials and gauges
found in modern cockpits. The Electronic Flight Instrument System (EFIS) in particular employs many different
colours. Although these systems are designed to provide critical information in monochrome in the event of
colour failure, it has been shown that the addition of colours facilitates the perceptual process and improves the
understanding of geometrical figures. Colours are likely to be increasingly important in the virtual cockpit
environment of the future. With ever-increasing sophistication of aircraft, the tendency for information overload
remains, and colour discrimination in all parts of the spectrum is desirable. The older colour perception testing
methods which were mainly concerned with congenital red-green defects in men will not suffice because they
fail to detect yellow-blue defects which are frequently seen in gender-neutral acquired colour vision
deficiencies.
11.2 EXAMINATION TECHNIQUE
11.2.1 A careful history of all eye problems is of special importance in the assessment of an applicant.
Where there is a history of ocular injury, surgery, use of eye medications, photophobia, constant use of tinted
spectacles, irritation or itching of the eyes, current or previous use of spectacles or contact lenses, eye
discomfort and headaches caused by close work or difficulty seeing in the dark, the applicant should be
Part III. Medical Assessment
Chapter 11. Ophthalmology III-11-3
referred to an ophthalmologist. Family history of pigmentary retinopathy, other tapeto-retinal diseases, optic
nerve disease, corneal dystrophy or glaucoma should be noted. Early-onset cataracts, strabismus and retinal
detachment in family members may be important. The applicant should be questioned about symptoms
including blurred vision at distance or near, undue light sensitivity, eye pain, irritation or itching, discharge from
the eyes, excessive tearing, double vision, visual fatigue, and any difficulties with spectacles or contact lenses.
11.2.2 Assessment of the visual function will be considered with later. Clinical examination of the eyes
includes external examination of the eyes and adnexa, evaluation of the pupils, ocular movements, ocular
alignment, funduscopy, visual field assessment and colour vision testing. Attention should be given to any
significant facial asymmetry and to abnormal position of the eyelids or eyelashes, particularly caused by
inversion or eversion of the lid margins. Exophthalmos or enophthalmos should be noted. The integrity of the
lacrimal drainage system should be ascertained, especially if there is a history of nasal or other facial fractures.
Corneal scars may result from trauma, corneal dystrophy or keratitis including herpes simplex, trachoma and
many other inflammatory diseases. Pericorneal congestion, pain, blurred vision, light sensitivity, tearing and a
small or irregular pupil suggest acute anterior uveitis and should prompt urgent referral to an ophthalmologist.
11.2.3 Pupils should be evaluated with regard to size, shape, symmetry and reaction to direct and
consensual light stimulus and to a “near” stimulus. The swinging flashlight test1 should be carried out to look for
an afferent pupillary defect.
11.2.4 Ocular excursions should be tested to look for any impairment in extraocular muscle function
implicating cranial nerves III, IV or VI. Evaluation of ocular alignment, visual fields and colour vision will be
discussed later.
11.2.5 Funduscopy should be done in a systematic manner looking at the optic disc, the major vessel
arcades and the macula. Some examiners may be comfortable performing tonometry, usually with an
indentation instrument such as the Schiøtz2 tonometer, but if there is any question about the intraocular
pressure, the applicant should be referred to an ophthalmologist.
11.3 ASSESSMENT OF VISUAL ACUITY
Distant visual acuity
11.3.1 Although measurement of visual acuity is a routine procedure in general medicine and the most
fundamental way of assessing visual function, there is still no internationally accepted standard test procedure.
The generally accepted tests are based on the minimum visual angle. These tests measure the ability to
distinguish two objects as separate. The earliest observations on visual acuity were made about 2 000 years
ago by Persian astronomers who found that normal persons were able to distinguish more than 700 stars in the
sky on a clear night. The classical measurements were made by the English physicist Robert Hooke
(1635–1703) who noted that people with “normal” vision could just distinguish as separate the twin stars Alcor
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Manual of Civil Aviation Medicine 2(35)
