new glasses and seasickness?

[VO5]

Extensive resarch over a very long time has been conducted into the causes for seasickness.

It has been found that there are four major causes:

1. Not being properly hydrated.
2. Clothing not warm enough.
3. Wrong food (greasy).
4. Tiredness.

Or a combination thereof.

Additionally it has been found that the cochlea (which is the little spirit level in the inner ear ) does not like being inverted.

This means that crouching positions in a heaving sea constutes asking for trouble. The longer an inverted position is maintained, like digging in the bilges or working in the engine room during movement, the longer the cochlea takes to recover its resistance to motion sickness.

I am very rarely seasick. This is because I am mindful of standing up, sitting or lyiong down flat when at sea.

I have never heard of varifocals causing nausea, though I stand to be corrected if it is found to be an additional cause.

In Germany a study was carried out that shows more than 70% of sailors suffer from the malady. I know its awful. I am very lucky. SWMBO does not suffer either, and we have been in some blows together, I assure you.

I am interested to learn of any new findings.

 

[alan_d]

I do NOT recommend Specsavers. My glasses were supplied by an independent optician who took some one and a quarter hours over my eye inspection but the glasses were not cheap even though my eye test is now age related free.

I'm not clear why you are advising against Specsavers. Have you had a bad experience with them?

 

[andygc]

It has been found that there are four major causes:

1. Not being properly hydrated.
2. Clothing not warm enough.
3. Wrong food (greasy).
4. Tiredness.

Or a combination thereof.

Additionally it has been found that the cochlea (which is the little spirit level in the inner ear ) does not like being inverted.

Shall I?

Oh well ...

Motion sickness is provoked by an unconscious, perceived mismatch of positional information obtained from the eyes, the balance organs in the inner ear (not the cochlea, you use that for hearing) and other sensory organs such as skin touch nerve endings and proprioceptors in muscles and joints. The first two are by far the most important. It is very strongly influenced by personal susceptibility - some people are never sick, some people throw up when they leave the dock on a calm day. It is influenced by adaptation - getting used to the motion over time - and retentivity - the ability of the brain to retain adaptation when away from the stimulus - in this case being in a boat.

Of VO5's 4 main causes, the fifth, alcohol, is of most significance because of its effects on the semicircular canals of the inner ear (I think it might take to long to explain here but I will if you really want to know). Anybody who is sensitive to motion sickness should drink no alcohol in the 24 hours before going to sea - even half a pint of beer is enough to affect the function of the semicircular canals.

Being cold, hungry and tired don't help.

It is entirely reasonable to suggest that varifocal lenses could provoke motion sickness in somebody not used to them and who has some degree of sensitivity.