Assessing vision

Purpose Definitions Responsibilities Requisites

Procedure Important points Special cases Points to remember

Purpose: To document the vision accurately for each eye as vision recording is the most important documentation in a patient history Documentation of vision is most important in many situations as legal, postoperative and injury and the M.L.O.P has to give utmost importance for this single test done by them. To assess the ability to distinguish the shapes and details of the things one can see by measuring the visual acuity of the patient using vision testing charts. To identify patients with decreased vision

Definitions VA : Visual Acuity - the patient’s ability to see an object at a particular distance Snellen chart : Eye chart used to measure visual acuity PG : Present glass HM : Hand movement CFCF : Counting fingers close to face PL : Perception of light

NO PL : No perception of light Occluder : A device which blocks light to one eye Amblyopia : Amblyopia is the medical term used when the vision in one of the eyes is reduced because the eye has lost its potential to see due to some eye problem like squinting of the eye in young age Aphakia : The absence of the lens of the eye PH : Pin Hole

OD/RE OS/LE CC SC PR BCVA Oculus Dexter / Right Eye Oculus Sinister/ Left Eye CC Cum correction/ with correction SC Sine correction/ without correction PR Projection of Rays BCVA Best Correction Visual Acuity

Identifying the correct patient Preparing for vision assessment. Responsibilities Identifying the correct patient Preparing for vision assessment. Properly performing the vision assessment 4. Documenting vision assessment in the medical record

Requisites Physical Room size 6m or 3m Multi letter Snellen or E chart ( 6m/3m ) Torch light Occluder Adequate illumination Pin hole

Materials Required - Distance Vision Test Snellen’s Chart Occluder Torch Light Measuring Tape 6 metres/ 20 feet Numbering Chart Alphabet Chart Tumbling ‘E’ Chart Adequate lighting and a room with a minimum length of 6 metres or 20 feet

Skill and attitude Skill to explain clearly Empathy with the patient 3.Communication skill 4. Dedication to follow all steps

Procedure Identifying the correct patient Call the patient politely with respect. Go near the patient and talk to the patient whenever possible Use appropriate words to address them depending upon their age / status Verify the name of the patient with the name in the medical record Collect the ID card and verify that the M.R. No. in the ID card is same as in the medical record.

Process Flow of Vision Test Step 1 - Receive the patient Correct treatment to the correct patient 1. Identify the correct patient Reduces the fear and tension 2. Talk in polite manner The patient may feel tired or with stress 3. Be compassionate If not cooperative make the patient sit calm for some time and test vision 4. Stay utmost tolerant to get accurate findings

Preparing for vision assessment Ensure good natural light or illumination on the chart . Position the patient 6 / 3 meters away from the illuminated vision chart. Make sure the level of the patient‘seye is equal to the level of Snellen chart to avoid parallax error Ask for the general history of the complaint – time of onset, symptoms, the eye to be tested etc. Check for past history of treatment taken Check the usage of spectacles and duration.

Step 2 – History Taking What is your problem? In which eye do you have the problem? How long have you had this problem? Do you wear spectacles? How long have you worn them? When do you wear them?

Examine the anterior segment with torch light, Direct any emergency patient immediately to doctor

Step 3 – Torch Light Examination Lens Cataract Cornea / Conjunctiva Infection Redness Pain Eyelids Stye Blepharitis Chalazion

Explain the procedure to the patient. I will show you a set of letters for you to read. While reading cover the other eye and do not look through the other eye to make accurate measurement of your vision status It is not a test that you have to pass, but a test to help us know how your eyes are working. Keep your eye relaxed Do not guess if you cannot see .

Have the patient fully cover the left eye with an occluder. Assessing vision Have the patient fully cover the left eye with an occluder. Patient's hand should not be used; It may encourage peaking through fingers. Also instruct the patient to leave the eye not being tested open . Closing the eye will cause squinting of eye being tested

Ask the patient to read the letters from left to right on every line down the chart until the patient misses more than half of the letters on one of these lines. If the patient cannot read the letters due to language difficulties, use an E chart. Ask the patient to point in the direction, the ‘legs’ of the E are facing.This has to be explained clearly to the patient so that he or she understands if we are testing illiterate patient in camps

Instruction to patient Capital letter E in decreasing sizes (arranged in different directions ) Instruction to patient Look at the chart carefully and say in which direction the legs are pointing for the letter which I am pointing In the example shown , it is pointing upwards

If the patient is not able to read even the largest letter at the top, stand from 5meter away from the patient and ask the patient to count the fingers five times. If the patient responds correctly three times, stop and record the vision If not reduce the distance by one meter and find the distance at which the patient is able to count the fingers

I If the patient is not able to count even at the shortest distance ( ½ m ), show the fingers close to face in front of the face (FCF – finger close to the face ) five times. If the patient responds correctly three times, record FCF. If not move the hand in front of the face only five times and check If the patient detects hand movement three times record HM

. If the patient is not able to detect hand movements close to face, shine light on the eye from a distance of 33cm to 40cm ( only five times ). If the patient is able to detect the light, then note pupillary action (constriction of the pupil) .If the pupil is not reacting, do not document as PL. ( Surgeries can not be done for a NOPL patient because there will not be any improvement in vision ) If the light is very close, patient will feel the heat and respond ‘yes’ Check whether the patient is able to detect the direction of light by shining light from the four directions – top, bottom, left, right

Repeat the same for other eye also If the patient is wearing glasses, repeat the procedure with glasses for both the eyes.

. Documentation Record your name, date and time, in the medical record ,in the appropriate column If the patient is able to read all the lines(7 lines), record visual acuity as 6/6 If the patient is able to read only six lines record the VA as 6/9 .Similarly, if the patient is able to read only five lines record the VA as 6/12

If the patient is able to read only four lines record the VA as 6/18 . If the patient is able to read only four lines record the VA as 6/18 If the patient is able to read only three lines record the VA as 6/24 If the patient is able to read only two lines record the VA as 6/36 If the patient is able to read only the first line record the VA as 6/60

On any line, if the patient reads the line partially, record the VA as partial for that line – eg. 6/36 P If the patient is not able to read only one letter in a line record that - eg. 6/36 -1 If the patient is able only to count the fingers at a particular distance, record the VA corresponding to that distance – eg. for 3m, record VA as 3/60 If the patient is able to count fingers, close to face record as FCF If the patient is able to detect only hand movement close to face, record as HM If the patient is not able to detect hand movement but detects light, and there is pupil constriction, record as PL

If the patient is able to say the direction of the light, record as PR corresponding to the directions in which light is detected If the patient is not able to detect light, record as NOPL . Record the visual acuity for each eye separately with and without correction- Eg. Right eye (OD) Left eye (OS) 6/18 6/12 6/6 P 6/ 9 (with spectacles)

(Unable to detect light in the direction marked ‘-‘ ) Documentation for PR + + - + + - + (Unable to detect light in the direction marked ‘-‘ )

If the patient ‘ vision is less than 6/6 use pin hole to check whether there is any improvement. Based on the vision examination, escort the patient to the concerned unit/ specialty / doctors

. Important points Make sure the patient is viewing the chart properly / eyes are closed accurately / head position is correct /eyes are not squeezing etc.

Test the eyes one at a time, at first without any spectacles (if worn). Test the ‘worse’ eye first (ask the patient out of which eye they see best). This ensures that the minimum is read with the ‘worse’ eye, and more will be read with the ‘good’ eye. This means that no letters are remembered, which could make the second visual acuity appear better than it is.

Make sure that the patients do not press the occluded eye; this is not good for an eye that has undergone surgery. It can also make intraocular pressure reading inaccurate It will distort vision when the occluded eye is tested

Make sure vision is checked with and without glass for the patient who already uses spectacles or contact lens While using charts use different types of charts for each eye ( number chart / letter chart ) to avoid recalling from memory Wash your hands thoroughly after testing any infected patient.

Special cases Handling dissatisfied patient Listen politely and find out the reason for the dissatisfaction Explain the importance of testing Explain the reason for any delay and convince the patient

2.Incase of vulnerable / wheel chair patient Give priority and complete the testing as quickly as possible 3. Non- cooperative patient Inform senior refractionist about the same. Allow the senior refractionist to assess the vision

4.Patients from other states Find out the language of the patient Get the help of a MLOP who is fluent in that language to assess vision

5.Spend more time with the following patients Unable to comprehend instructions due to language barrier Difficulty in hearing Uncooperative patients (who squeeze or close the eye during examination) Paediatric patient

5.Prioritising the patient Injury Redness ,pain Sick patient Corneal ulcer Elderly disabled patient/ wheel-chair person Appointment patient

For emergency patient (corneal injuries) direct the patient immediately to the doctor. During camps, for vision measurement use a rope to measure the distance at which the acuity chart is placed. (6m)