How can you check that DVLA field of vision machine is OK.

[WindyParticipant @windy30762]

 

How can you check that DVLA field of vision machine is faulty?

In 2005 600 people lost their driving license due to a field of vision software problem the DVLA would not say the name of machine.

Eventually when the fault was discovered the 600 were given the option to retest many never bothered as had sold their car.

My own test 3 years ago was nearly a 100% pass and been like that since 2005 when I found had a static field of vision defect caused by a head injury about 1964.

Just had another test thanks to my local MP giving DVLA a push after waiting since 19th November 2020 for test I had been patient due to the Virus.

As soon as started test memory cells were working have they a new software program as started different to previous tests and  something was wrong with my sight or machine.

The Humphery 740i had been serviced three months before my test as an age related test my age was entered correctly.

Went to my optician and no change in normal sight and eye pressures normal.

I don't rule out that suddenly a fresh eye problem has happened and just waiting for NHS eye clinic check.

Two friends a few years ago failed the tests and passed when Hospital tested them.

 

 

Edited By Windy on 22/04/2021 22:29:29

Edited By Windy on 22/04/2021 22:32:47

[WindyParticipant @windy30762]

How can you check that DVLA field of vision machine is OK.

[Michael GilliganParticipant @michaelgilligan61133]

I’m afraid it doesn’t really answer your question, Paul

… but here’s the product brochure, if it’s of any help

**LINK**

https://www.zeiss.com/content/dam/Meditec/us/download/certified-pre-owned-systems/perimetry-brochure-HFA.pdf

MichaelG.

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Edit: __ and the 329 page User Manual :

 https://www.manualslib.com/products/Zeiss-Humphrey-740i-8750724.html

Edited By Michael Gilligan on 22/04/2021 22:44:59

[WindyParticipant @windy30762]

Michael I have looked at that link before when wondering if a machine fault.

Another field of vision machine it's lamps can go dim and need an increased voltage to correct the glow.

There could be a fault with my vision and having an inquisitive mind want to know the cause.

Was the same with my old speed machine and flash steamer if could would sort out the fault.

[V8EngParticipant @v8eng]

Have you asked your regular optician to do a field test (mine could) for confirmation?

I cannot remember which  particular machine was used for my DVLA test so will see if I copied the paperwork.

The test seemed different to previous years but at the time I was feeling more concerned about a government department forcing me into a town centre store during lockdown.

Edited By V8Eng on 22/04/2021 23:44:14

Edited By V8Eng on 22/04/2021 23:44:27

[Dr. MC BlackParticipant @dr-mcblack73214]

My late Mother was a little forgetful

She was given a Field Test by her Optometrist.

It was reported that she had defective vision and was referred to Hospital

After several visits to hospital, it was concluded that there was nothing wrong with her eyes but she had forgotten what she was supposed to do with the button in her hand when lights flashed inside the machine.

She was subsequently diagnosed with Dementia.

The person administering the test should have reminded her to push the button when you see the light flash before every flash.

That is obviously something missing from the Optometrist Training course!!

Mother never drove a car; she was a little dangerous with a borrowed mobility scooter in department stores. We discovered that the big display stands move when hit by a mobility scooter. Riding in a straight line was OK but corners were more of a problem.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Windy on 22/04/2021 23:31:34:

Michael I have looked at that link before when wondering if a machine fault.

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Sorry … I appear to have wasted your time then.

The short answer to your opening question is almost certainly : You cannot check it

It’s a sophisticated machine made by one of the World’s best optical companies, and although they can do various calibrations of it … you are the biggest variable in the whole test loop.

The only practical thing I think you can do, is take at least one more test and compare the results … but even then, [aside from any actual ophthalmic defects] your level of attention will most likely vary between tests.

MichaelG.

[Martin ConnellyParticipant @martinconnelly55370]

You can test yourself, with one eye shut or covered and looking straight ahead move your fingers with out-stretched arms. Move them from behind until you can notice the movement. Do this from above, below and both sides. You should be able to see movement (don't expect to be able to count your fingers, just notice the movement) from close to 85° from straight ahead except for the directions where the nose/brows/chin blocks the view (this bit depends on facial shape so may not be applicable for every face shape). Repeat for the other eye.

When you realise how much peripheral vision you have with normal eyesight you can understand why losing it may be considered a bad thing for drivers. One of my uncles lost the vision in one eye when he was in his sixties and for a long time kept bumping into people and objects because he was not aware that they were near. He had to learn to move his head in a sweeping motion to get a full view ahead.

Martin C

[Nick Clarke 3Participant @nickclarke3]

The day job is concerned with teaching blind and VI students but as far as field defects we only check for functional vison – ie how it affects reading, mobility, use of a computer etc and don't use any machinery to get a more exact record.

However as I was interested in Windy's post I checked on the Gov.uk website and found out that for bus and lorry drivers the required standard was:

"You must have an uninterrupted horizontal visual field of at least 160 degrees with an extension of at least 70 degrees left and right and 30 degrees up and down. No defects should be present within a radius of the central 30 degrees"

All OK but for car drivers it was:

"You must have an adequate field of vision – your optician can tell you about this and do a test"

What is adequate?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Nick Clarke 3 on 23/04/2021 07:44:06:

[…]

All OK but for car drivers it was:

"You must have an adequate field of vision – your optician can tell you about this and do a test"

What is adequate?

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It seems quite clearly stated here, Nick : **LINK**

https://www.gov.uk/guidance/visual-disorders-assessing-fitness-to-drive

Under the heading Minimum standards for field of vision – all drivers

MichaelG.

[WindyParticipant @windy30762]

I saw my optician a few days after the test normal eye vision no change for the last 4 years, pressure in eyes normal. the field of vision the optician used is not dvla approved or was set for binocular vision.

Right eye one missed point left was bad but screen was misting due to my breathe.

As the eye consultant said in a copy of his 2005 letter to my Doctor it's a static field of vision defect so unless things have changed am in the dark.

Maybe after the eye clinics have done their investigations will know if any change in my field of vision.

There is another possibility when on medication some can effect your vision beta blockers then tamsulosin and dry eye can sometimes cause eye problems.

I had just started with them when I did last successful field test 3 years ago.

Have done home tests with fingers that seems OK the Amsler grid takes a bit of messing about to get right distance but lets you know if there is a field of vision defect.

I do have a defect but have met the driving standard for many years just this year there are doubts.

Edited By Windy on 23/04/2021 09:14:20

[Nick Clarke 3Participant @nickclarke3]

Ah a different page on the same website – I searched for 'Driving eyesight rules' on Gov.uk and got the far vaguer information I quoted.

Thanks Michael – If I needed the information as against looking out of curiosity they don't make it easy, do they!

[WindyParticipant @windy30762]

At Specsavers they will not give you a copy of your DVLA test you have pay for a private test to get a copy.

My previous test the lass can't have known that I was given the results.

How I knew about my vision defect in mid 1990 was at A/E with metal in my eye and mentioned about my Dads Mum and Sister went blind so they started a long series of tests in case it was heredity.

At first was thought to be Glaucoma due to field defects so that is now on my medical records (166 pages of it).

Mr Manners eye consultant had his suspicions it was not Glaucoma and I had a head scan was found a head injury was cause of static field defect.

Think that was when fell of a road motorcycle and cracked my skull in the 1960's.

Any young person that has a parent die young an example heart attack get regular medical check ups to prevent you going the same way.

I have a close young friend and relative their Dads died at between 40 and 50 the relative has heredity heart problems but modern medication lets him live a useful life he is in his 70th year.

[Adam MaraParticipant @adammara]

I had an 'eye stroke' on March 3rd 2020, the DVLA revoked my licence, and said I must take the test within 3 weeks. Then covid happened, and tests were cancelled. In September my optician said my eyesght was OK and filled a form sent by the DVLA, but this was rejected! In January 2021 I had a Humphrey test in hospital during a check up, and was told that SpecSavers were carrying out the test, although I was not informed by the DVLA. Booked a test at SpecSavers, but when I got there was told my case number was not valid, so paid for a private test, the results were sent on to the DVLA on January 12th.

Just over 11 weeks later, I had a letter asking me so send the results! Still waiting.

[WindyParticipant @windy30762]

As soon as I did the Specsavers test knew something was wrong.

Saw my optician in a few days after normal sight was ok.

Today a phone call to arrange an appointment for the glaucoma clinic.

Might find out what has caused this sudden change in field of vision.

I still have my suspicion its a faulty software.

When old every minute counts like many large departments they are bullet proof even when they make mistakes look at the PO scandal

[Dr. MC BlackParticipant @dr-mcblack73214]

Posted by Adam Mara on 23/04/2021 22:04:26:

……, the results were sent on to the DVLA on January 12th.

Just over 11 weeks later, I had a letter asking me so send the results! Still waiting.

It seems to me that it's worth paying for Registered Post in cases like this!

MC

[Mark RandParticipant @markrand96270]

On a side note:- the minimum acceptable visual acuity is 6/12 for normal licenses and 6/7.5 in the better eye for lorry drivers. Many opticians and hospitals use reduced size eye chart at 3 metres distance. This really winds me up because my varifocal glasses are optimised for things such as keyboard use, screen use and distance use. 3 metres is not their optimal range, but 6 metres, as specified, is well within it.

Bah Humbug!

[Paul RhodesParticipant @paulrhodes20292]

Windy, the screening eye tests are subject to many variables from dementia as above, arthritic hands, or just not having a good day! You illustrate this yourself by declaring a static field defect, yet claiming near 100% pass in recent tests. Quite correctly the screening errs towards false positives rather than false negatives so that early warning and treatment is offered to asymptomatic patients at an early date. The cost of this is alarming a small number who have nothing wrong with them.

Mark, I doubt the professional use of half size printed charts. If they use professional screens ,due to size of room, they are very accurately calibrated and are no different to a 6 m printed chart(all to do with the angle the image subtends at the retina etc). Frankly I do not see how this makes any difference to your visits to the optician. With varifocal being a gradation, you should simply move your head to find the sweet/sharp spot. Personally I think varifocals are a money spinner for opticians and am invariably disappointed by them….others love them.

[WindyParticipant @windy30762]

Waiting 45 minutes finally spoke to a DVLA adviser this morning the good news have passed.

I certainly had problems which I never had on my five previous tests.

Am having a check at the eye clinic to make sure I know why this happened.

Having close family and friends with serious eye problems MD and cancer am very cautious with my eye conditions.

Certainly amazed I passed makes me wonder if having my MP involved shook them up.

Like all my speed related records will never give up and want the finer details of why things go pear shaped.

Another visit to hospital in May regarding a common hand operation that seems to affect persons who manually use their hands a lot have lost hand feelings my doctor said emergency operation after many years of living with it..

[Mark RandParticipant @markrand96270]

Posted by Paul Rhodes on 24/04/2021 21:41:39:

Mark, I doubt the professional use of half size printed charts. If they use professional screens ,due to size of room, they are very accurately calibrated and are no different to a 6 m printed chart(all to do with the angle the image subtends at the retina etc). Frankly I do not see how this makes any difference to your visits to the optician. With varifocal being a gradation, you should simply move your head to find the sweet/sharp spot. Personally I think varifocals are a money spinner for opticians and am invariably disappointed by them….others love them.

Not so.

The 3m charts, while half the size of 6m charts and having the same angles as the version are still at 3m distance instead of 6m distance. My varifocals, as are many others, are optimised for .3m, .6m and infinity and aren't a continuous variation. 3m is at about the worst possible distance for me to focus There is no sweet spot to cover 3m. I won't use an optician that uses the 3m Snellen chart instead of the 6m one.

The way that opticians normally get around smaller rooms is by using a reversed 6m chart and a mirror, but one doesn't always get that choice with people who aren't opticians.

[Michael GilliganParticipant @michaelgilligan61133]

I agree, Mark … fudging the size and distance is a ludicrous idea

The simple maths makes it look logical, but it’s not the same test !

MichaelG.

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https://www.pandamed.co.uk/product/3m-dvla-snellen-chart/

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Edit: This next one includes an interesting [and not intuitively obvious] comment:

 https://k2.kaysmedical.com/productdetails/3m-vte-direct-eye-test-chart–dvla-75/5905

”Our DVLA eye test chart is a 3m Snellen style eye chart. The chart is made of plastic and perfect for hanging on a wall. Our direct eye test chart conforms to DVLA standards. It includes the 7.5 test line as introduced by the DVLA and must be viewed from 6m away.”

 

Edited By Michael Gilligan on 25/04/2021 21:23:55

[Paul RhodesParticipant @paulrhodes20292]

Michael please explain the "fudge". I naively thought that simple maths was the basis of optics. It is perfectly possible to get identical results from a 3m Snellen as a 6. A 3 m chart is more sensitive to positional errors than a 6.

Mark you clearly hold a view on this which is strongly felt ,but despite Michael's support seems illogical. If you apparently can not focus adequately at 3m then whether that object is a larger one which has arrived from 6 m it is still the same size that you have to identify at 3m. I simply can not follow why you feel you can read accurately at 3 m in one system but not at 3 metres when the image size is identical, but derived differently.

As for varifocals tuned to there distances onlyIf you had simple trifocal less with an absolute correction I would see your point, but the variable blended lens should give you satisfactory vision all the way out.

I may be misunderstanding varifocals , and my mathematics was always fudged( at best), so please correct me.

Paul

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Paul Rhodes on 25/04/2021 21:40:11:

Michael please explain the "fudge". I naively thought that simple maths was the basis of optics. It is perfectly possible to get identical results from a 3m Snellen as a 6. A 3 m chart is more sensitive to positional errors than a 6.

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It’s simple, Paul … the maths works out fine … but the ergonomics doesn’t

The underlying requirement is to be fit to drive … The number-plate reading test being a simple and appropriate method. But halving the test distance can [and in Mark’s case, does] bring ‘failures’ which are not relevant to the driving scenario.

Yes it is “perfectly possible to get identical results from a 3m Snellen as a 6” … but it is not inevitable.

MichaelG.

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P.S. __ it would be a simple matter to add another layer of fudge, by letting Mark wear corrective lenses matched to the 3m test distance … That should work; but then he wouldn’t be tested wearing his glasses.

Edited By Michael Gilligan on 25/04/2021 21:57:32

[Adam MaraParticipant @adammara]

Posted by MC Black on 24/04/2021 00:40:42:

Posted by Adam Mara on 23/04/2021 22:04:26:

……, the results were sent on to the DVLA on January 12th.

Just over 11 weeks later, I had a letter asking me so send the results! Still waiting.

It seems to me that it's worth paying for Registered Post in cases like this!

MC

It was, and was recieved 2 days later!

I ended up with severe double vision, corrected by very expensive prism lenses. A pair for reading, a bifocal pair for computer use and watching telly and finally a long distance pair. Cost more than a years car insurance, tax disc and servicing combine!

[Paul RhodesParticipant @paulrhodes20292]

Michael,

I do not wish to be unduly provocative but you don’t explain what you mean by ergonomics in this matter.I have accepted that the “simple mathematics” are more prone to error at 3m. But we seem to agree that otherwise the test is the same.

If by ergonomics you are referring to the new point you raised about the crude and arbitrary Snellen test being the sole determinant of safety to drive, then we are fully in accord. It is an expedient screening for gross defects in visual acuity. VA is but one component of vision in driving.

I am sorry but I still find it unconvincing that Mark’ varifocals should give a sharp image at 3m when the object came from 6 via a mirror, but be difficult/ impossible when reading at exactly the same 3m when reading the half sized image.. This is not to doubt the honesty of Mark’s assertions but rather to question the science that both you and he accept.

[Author]

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