Hello,
Thanks for the query.
Your rectal surgery doesn't have any connection with your black eye.
The most likely cause for such a black eye is generally a trauma and it might have occurred in your sleep.It is not unusual to throw up a arm or hitting some object while turning in bed.
The blood vessels around he eyes can easily be broken with an injury which was not strong enough to have awakened you.
The other possible causes could be some allergy or some bite or some infection around your eyes,but there should be other associated features with that.
I don't think there is anything to worry but best would be,to consult your doctor and ask his opinion about this.
I hope it helps however you may revert to me for any further query.
Best of luck
Thanks

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