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Nandipha  Maci Ruqaiyah  Peer Seyuri Bisetty Andile Ngema

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Quantitative measure  Routinely performed to measure the eye’s                           ability to distinguish the details of an object Ability to resolve black symbols on a white                                   background at different distances Represents the smallest font that can be read Done at distance and near

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Why is distance VA important in a LV exam?

The assessment begins with determining the distance acuity of the patient. Starting  point  in the process of achieving the target goal.  Aids in the  determination of magnification  required for prescribed optical devices Assess  eligibility for low vision services   To monitor  progression  of certain ocular conditions.

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LogMAR  chart Snellen chart LVRC flip chart BRVT charts

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Why the  logMar  chart is The Gold standard than Snellen Chart

The  logMar  chart is preferred in low vision VA testing because: Shows proportional spacing between each letter and each line It allows examiners to be able to explain visual acuity using a Single number  Consistent number of optotypes in each line (5)

TOZ
r ELOPZD
DE r POT EC
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20/200
20/1 oo
20/70
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V D R SN
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VAR
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PROCEDURE OF ASSESSING DISTANCE VISUAL ACUITY

1. Always start with monocular visual acuity and record separately.  2. If patient reads 5 letters in a row, record the  LogMAR  unit as shown on the right hand side of the chart  3. Each letter on a line of the  LogMAR  chart contributes 0.02 log units. The higher the  LogMAR  VA the worst the VA is. 4. If patient read 4 letters only in a row, then add 0.02 to the  LogMAR  unit on the right of the chart 5.  5. That is if the patient reads at 4m if they cannot see at 4m you half the distance and add 0.3 @ 2m  to your  logMar  value and 0.6@ 1m.

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Demonstration on How To Test visual acuity at Distance in a Low vision Patient

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There are two methods on how you calculate your VA. Patient was able to read at 1m   one letter  at the  0.8 line  on the  logMar  chart  and read  four incorrect letters . Method 1 LogMar  = 0.8 + (0.3x2) + (0.02x4)                =  1.48 Converting To Snellen Equivalent Visual Acuity Mar = 10^1.48     	= 26.30 26.30 x 6m = 158     	VA =  6/158 Method 2 LogMar  = 0.8 + (0.3x2) – (0.02x1)                =1.48 26.30 x 6 = 6/158

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Type of illumination The chart used  Posture : Does the patient present with a head tilt? Use of eccentric viewing? Aided or unaided?

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If VA improves with pinhole - indicates that the  patient  will benefit from a refractive correction.  If the VA  does  not improve - implies the presence of possible pathology or amblyopia.  If the VA gets worse - the patient could have media opacities present and multiple pinhole VA should be taken.

Distance VA

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