158The following steps are taken to assess loss of central vision in one eye.

158     The following steps are taken to assess loss of central vision in one eye.

| Step 1 | Measure the central acuity for distance and near, correcting for any refractive errors and presbyopia, and record the result. | | Step 2 | Consult Figure 6-C: Percentage loss of central vision in one eye to derive the overall loss, combining the values for corrected near and distance acuities. | | Step 3 | If monocular aphakia or pseudoaphakia is present then add 50% to the percentage loss of central vision obtained from Figure 6-C: Percentage loss of central vision in one eye. |

Figure 6-C: Percentage loss of central vision in one eye

• Distance vision (metric 6) Revised LogMar standard for near vision
• 0.3 0.4 0.4 0.5 0.6 0.7 0.7 0.7 0.8 0.9 1.0 1.1 1.3 1.6
• 6/5 0 0 3 4 5 25 27 30 40 43 44 45 48 49
• 6/6 0 0 3 4 5 25 27 30 40 43 44 46 48 49
• 6/7.5 3 3 5 6 8 28 30 33 43 45 46 48 50 52
• 6/10 5 5 8 9 10 30 32 35 45 48 49 50 53 54
• 6/12 8 8 10 11 13 33 35 38 48 50 5 53 55 57
• 6/15 13 13 15 16 18 38 40 43 53 55 56 58 60 62
• 6/20 16 16 18 20 22 41 44 46 56 59 60 61 64 65
• 6/22 18 18 21 22 23 43 46 48 58 61 62 63 66 67
• 6/24 20 20 23 24 25 45 47 50 60 63 64 65 68 69
• 6/30 25 25 28 29 30 50 52 55 58 68 69 70 73 74
• 6/38 30 30 33 34 35 55 57 60 70 73 74 75 78 79
• 6/50 34 34 37 38 39 59 61 64 74 77 78 79 82 83
• 6/60 40 40 43 44 45 65 67 70 80 83 84 85 88 89
• 6/90 43 43 45 46 48 68 70 73 83 85 86 88 90 92
• 6/120 45 45 48 49 50 70 72 75 85 88 89 90 93 94
• 6/240 48 48 50 51 53 73 75 78 88 90 91 93 95 97

6.2        Determining loss of monocular visual fields

159     There are many ways of measuring the visual field. The most common are the manual Goldman Field and the Humphrey, Octopus and Medmont computerised field analysers. If using a computerised field it is necessary to test at least a 30-2 threshold.

160     An Esterman Binocular Field is suitable for the majority of visual field impairment assessments. The field is tested with the employee wearing spectacles and both eyes open. The binocular field result is assessed by using the Esterman 120‑unit binocular grid, and the dot count is multiplied by 5/6 to obtain the percentage of retained or lost field. Note that binocular field-testing is not recommended when diplopia is present.

161     If the automated 30-2 Threshold Field is normal, and the ocular history and examination do not suggest lesions that would affect the outer part of the field, it is acceptable to conclude that the entire field is normal. Whatever technique is used to measure the visual field, the test should be performed by an ophthalmologist.