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Visual acuity examination(adult) Update (1).pptx
1. Visual acuity examination
for adult
CHAIRMAN : DR. MD. ASHIQUR RAHMAN AKANDA
Associate Professor
Department of Pediatric ophthalmology, NIO&H
MODERATOR : DR. CHANDAN KUMAR PAUL
Junior Consultant
Department of Pediatric ophthalmology, NIO&H
PRESENTER : DR. SONIA ISLAM
Phase A Resident NIO&H
2. Visual acuity
Definition: Visual acuity is the resolving power of eye by
which objects are distinguished clearly from other.
Visual acuity refers to the spatial limit of visual
discrimination.
Components of vision:
Visual acuity
Field of vision
Colour vision
Contrast sensitivity
Light Brightness sensitivity
3. Visual acuity
Components of visual acuity:
Minimum visible
Resolution
Recognition
Minimum discriminable or hyperacuity
4. Measurements of VA
Measurements of VA is done to monitor change in vision
with progression of disease and/or treatment plan.
It is the way to measure blurr vision.
VA must be measured on every patient at every visit.
Visual acuity depends on:
The refractive error of the eye
The health and integrity of eye
The test targets used
The test conditions
5. Clinical measurement of VA
Criteria:
Normal testing distance (distance visual acuity ) -6m
For near -33cm/40cm.
Illuminated visual acuity chart
Proper room illumination.
Steps :
Unaided VA ( OD,OS,OU)
Pinhole VA (OD,OS)
Aided VA(OD,OS,OU)
7. Procedure
Patient seated 6 meters from the chart
Illumination is 20 foot candles
Each eye is tested separately
VA is recorded as a fraction (6/60,6/36,6/24,6/12,6/9,6/6)
Numerator : distance of the patient from the chart
Denominator : smallest letters accurately read
8. Procedure
If the patient can not see the top line from 6m, he is
asked to slowly move towards the chart till he can read
the top line (5/60,4/60,3/60,2/60,1/60).
If the patient is unable to see even from 1 m, he is asked
to count fingers of the examiner.
When a patient fails to count fingers ,the examiner moves
his hands close to the patient's face & ask whether he
could appreciate the movement or not (HM +/-).
When the patient cannot appreciate hand movement,
perception to light is noted.(PL+/-)with projection of rays
in four quadrants.
11. Near Acuity Chart
Reduced snellel chart
N chart
M chart
Jaeger chart
12. Procedure (Near Vision)
Near vision tested by asking the patient to read a near
vision chart kept at distance of 16 inches (40cm).
Each eye should be tested separately and respectively .
Record the binocular acuity achieved.
The near vision is recorded as the smallest type which the
patient can read comfortably
13. Jaeger’s Chart
Consists of ordinary printer’s front of
varying sizes
Prints are marked from 1 to 7 and
accordingly patient’s acuity is labeled
as J1 to J7 depending upon the print he
can read
14.
15. Testing Pinhole Visual Acuity
Position the patient and occlude the eye not being tested.
Ask the patient to hold the pin whole occlude in front of eye that is being
tested. That patient’s habitual correction may be worn.
Instruct the patient to look at the distance chart through the single
pinhole.
Instruct the patient to use small hand or eye movement to align pinhole
to resolve the sharpest image on the chart .
Ask the patient to read the line with smallest letters that are legible to
determined on the previous vision test without use of pinhole
Record the Snellen acuity obtained and precede or follow it with the
abbreviation PH
18. LogMar scale
It stands for logarithm of minimum angle of resolution. The chart
was designed by Bailie & Lovie for the Early Treatment Diabetic
Retinopathy study (ETDRS). Which is designed to be used at a
distance of 4 Meter. Also known as Bailie & lovie Chart.
19. Steps
Set the patient 4 meters from the chart.
Cover one eye, if cannot read, then move 1 meter & add 0.6.
Repeat second eye.
If still unable to read, then use other option.
Example: It one read 0.4 line plus 3 letters of 0.3 line, he or she
will have a score of 0.4-(0.2x0.3)=0.34.
19
20.
21. Colour vision
This is the inability to distinguish certain colour .
Unexplained reduction in visual acuity e.g. 20/25
One or more cone type is missing or defective to any
extend.
Abnormal colour matching and colour confusion .
23. Colour Vision Test
1. Pseudoisochromatic test
a. Ishihara colour vision chart
b. AOHRR-American Optical Hardy Rand Rittle Plate
2. Arrangement test
a. Franswoth Munsell-100 Hue test
b. Fransworth D-15 test
c. Anamaloscope
Nagel’s anamaloscope
24.
25. Some Diseases Associated with Reduced VA:
Refractive errors
Cataract
Retinal detachment
Retinopathy of prematurity
Glaucoma
Optic nerve atrophy
Albinism
Nystagmus
26. VA is the most fundamental and basic clinical examination in
eye. Meticulous visual acuity assessment is essential. We all
should practice it. VA is impotent for clinically and medico-
legally. VA acuity is the opening door for examination of
eye.
Take Home Message
