Hello,
Thanks for the query.
The shadow you are feeling in your eye seems to be the floater in your eyes.
Floaters are pieces of debris found in vitreous humour of the eye,which is a jelly like substance found in the middle of eye ball.
Although floaters can be normal and caused by ageing process but there can be various causes for such floaters like
Posterior vitreous detachment
Retinal tears
Retinal detachment,in rare cases

However other causes may be
Eye injury
Eye inflammation like uveitis
Diabetes etc.

As floaters and eye flashes can be caused by many eye conditions,some of which can affect your vision,you must get your eye examined by a eye specialist as early as possible.

I hope to have answered your query however you may revert to me for any further query.
Best of luck
Thanks

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