Triskele, it sounds to me like you may have what is called benign essential blepharospasm (BEB)... "benign" indicates the condition is not life threatening, and "essential" is a medical term meaning "of unknown cause"... blepharo means "eyelid" in Greek, and spasm means "uncontrolled muscle contraction"... in addition, it is called both a cranial and a focal dystonia— cranial refers to the head, and focal indicates confinement to one part... the word dystonia describes abnormal involuntary sustained muscle contractions and spasms...

Your problem could be caused by something as simple as dry eyes... it has been observed that the signs and symptoms of dry eye frequently precede and/or occur concomitantly with blepharospasm... it has been suggested that dry eye may trigger the onset of blepharospasm in susceptible persons...

There are a lot of other things you don't want your problems confused with—

Ptosis— drooping of the eyelids caused by weakness or paralysis of a levator muscle of the upper eyelid
Blepharitis— an inflammatory condition of the lids due to infection or allergies
Hemifacial spasm— a non-dystonic condition involving various muscles on one side of the face, often including the eyelid, and caused by irritation of the facial nerve... the muscle contractions are more rapid and transient than those of blepharospasm, and the condition is always confined to one side...
Nystagmus— the jerking or jumping of the eye itself... this is an entirely different condition and an optometrist or ophthalmologist should be able to make a proper diagnosis after a full examination...

eye twitches are muscle spasms and, like most muscle spasms, they generally have no long term side effects...

other causes could be—

fatigue or lack of sleep
over consumption of caffeine
physical or emotional stress
anxiety or phobias
drain bamage or other neurological disorders
eye stress associated with extended viewing of the computer screen
Estrogen replacement therapy for women going through menopause

blepharospasm is thought to be due to abnormal functioning of the basal ganglia which are situated at the base of the brain... the basal ganglia play a role in all coordinated movements, but nobody knows for sure what happens with the basal ganglia to cause the twitches...

it can be treated with some drugs, and there are surgery options, but the best way to treat it by far is a proactive approach to decrease the overall daily stress... some ways to reduce stress are— exercising more, sleeping more, working less, meditation, and eliminating all forms of dietary caffeine (coffee, chocolate, cola, certain over-the counter medications, etc.)...

here's a video about it that you might find interesting, just for info—

Diagnosis & Treatment with Botox of Patients with Benign Essential Blepharospasm & Related Disorders

It explains a lot about BEB, and offers a subcutaneous injection of Botox as a possible treatment...

It's up to you to decide if it is bad enough for you to see a optometrist/ophthalmologist, but if they last more than a week, or make your eyes close completely, you might want to consider it...

and relax, because it is not a dangerous medical situation... sorry to hear you are having to deal with it... good luck with it... remember my disclaimer— I am not a doctor; I am just a humble blue-collar foot-washer... I am not making a diagnosis— just offering data...

Here's a list of inexpensive, over-the-counter skin care products... and I'm talkin' over-the-counter, as in drug store, not as in Saks Fifth Avenue... these reasonably priced products work just as well as their designer counterparts...

For Face
Cleansers:
- Moisturel sensitive skin cleanser (the one I love for winter dryness)
- Purpose liquid or bar (I use the liquid in summer)
- Cetaphil bar or liquid (really burned my eyes)
- Basis liquid cleaner for sensitive skin
- Oil of Olay fragrance free cleanser
- Eucerin gentle hydrating cleanser

Moisturizers for Face-Daytime-SPF:
- Purpose dual treatment
- DML for face
- Eucerin 25
- Ombrelle 15
- Oil of Olay for sensitive skin
- Not on list, because it's newer than list, but I use and love Neutrogena Healthy Skin Face Lotion, with SPF 15

Nighttime
- Oil of Olay daily renewal
- Complex 15 for face
- Eucerin Q10
- Kinerase cream or lotion (twice a day)

For Body
Moisturizers
- SBR lipo cream (great for flakey patches)
- Moisterel lotion
- DML forte
- Eucerin Plus
- Aguaglycolic lotion ($15 might be high for a drug store product, but this stuff works as well as designer brands. Caution, as with all glycolic acid formulas, don't use this after shaving. I also use the face cream version)
- Cetaphil moisturizing lotion or cream (I also use this)

Body Soaps (bar)
- Lever 2000 unscented (used to use, now unfortunately I'm in love with a French soap at $8.50 a bar)
- Dove unscented
- Cetaphil bar
- Dial sensitive skin

Body Soaps (liquid)
- Oil of Olay daily renewal
- Dove

Sun Blocks 
- Solbar AVO
- Pre-sun Ultra 30 lotion or gel
- Ombrelle 15, 30 (my choice)
- Vanicream SPF 15 or 35