Appendix 1 of Annex A - Instructions for Testing Visual Acuity

A-MD-154-000/FP-000

1. When testing Visual Acuity (VA), the member should not be wearing contact lenses on the day of the exam. For soft contact lenses, the lenses must be removed at least 24 hours prior to testing and for rigid gas permeable lenses; the lenses must be removed for at least 72 hours prior. The member should also bring their prescription glasses for the exam in order to test corrected vision. If these timelines have not been met, the VA screening test may need to be postponed.
2. VA is judged by the ability of the candidate to read with each eye separately, at a distance of 6 metres, appropriate letters on the standard slide of the Project O Chart, Series A. The projector must be calibrated so that the letters projected are of the standard size. To ensure this, the instructions contained in the booklet which accompanies the Project O Chart must be followed.
3. If the Project O Chart is not available, the usual Snellen Test types in chart form may be used. The illumination on the Snellen Chart must be of proper intensity, even, diffuse, and without highlights. The correct intensity of illumination is about 10 foot candles, as measured by a photographic light meter. This is equivalent to the effect of a frosted 150 watt light bulb at a distance of three feet. An accurate assessment cannot be made using a soiled chart or decreased illumination.
4. The procedure for testing VA is as follows:
   1. vision for each eye is tested separately, with the other eye occluded; and
   2. candidates must not be allowed to squeeze their eyelids or to posture their head as an aid to vision.
5. The VA for each eye is recorded as a fraction, using the number 6 as the numerator, and, for the denominator, the number of the lowest (smallest letters) line on the chart which can be read without error. Thus, if the lowest line which the subject can read bears the number 9, VA for that eye is 6/9. The grading of distant VA is in Table 1.
6. When uncorrected vision is below acceptable standards, the possibility of correction to normal shall be tested with the candidate's own spectacles. If correction to acceptable standards is not possible by these means, the candidate shall be referred for the opinion of a qualified ophthalmologist or optometrist.
7. The testing of near visual acuity is only conducted by ophthalmologists or optometrists for selected MOSIDs. The grading is presented in Table 2. The results of the distance vision test take precedence over the results of the near vision test.

Table of Visual Acuity Standards - Far Distance Vision

Note 1: Those who do not meet the V1 standard of uncorrected visual acuity must have a (current) refractive error measured.

Note 2: The spherical equivalent is equal to: (cylinder/2) + sphere.

Note 3: An ophthalmologist or an optometrist capable of performing a complete fundus examination must examine those whose refractive error exceeds plus or minus 7.00 dioptres (+/– 7.00) spherical equivalent in either eye to rule out any complications.

Note 4: Those with V5 standard of uncorrected visual acuity require fundoscopic examination every two years.

Table of Visual Acuity Standards - Near Vision

Near vision is to be measured by ophthalmologists or optometrists and only for aircrew where it is necessary.

Note 1: Near vision is determined using "Times Roman" type and is assessed at reading distance (30-50 cm) and at 100 cm. The 100-cm distance is important in the aircraft cockpit and similar environments and for users of CRT displays. When two values are shown, such as N5 and N14, the first value refers to the reading distance (30-50 cm) and the second value to the 100-cm distance.

Note 2: Approximate equivalents of the N type, the Jaeger type and the meterprint size are follows: N5 = J2 = 0,5m ; N6 = J3 = 0,6m ; N8 = J5 = 1,0m ; N10 = J7 = 1,4m ; N12 = J8 = 1,6m ; N14 = J10 = 2,0m ; N16 = J11 = 2,2m ; N18 = J12 = 2,5m ; N24 = J20 = 4,0m ; N36 = J30 = 6,0m