Blurred vision

# Overview
Blurred vision is a common ocular symptom which is define as a sudden or gradual loss of clarity or sharpness of vision and difficulty to see fine details.It can present unilateral or bilateral.

# Historical Perspective
There is not much information regarding the historical perspective of blurred vision.

# Classification
There is no established system for the classification of blurred vision.

# Pathophysiology
Blurred vision may result from refractive errors, opacity of structures (lens, cornea, vitreous), retina disorder or optic nerve disease.

# Causes
Blurred vision can be  caused by a wide range of eye conditions which include: 
- Refractive errors (most common)
- Age-related macular degeneration
- Cataracts
- Presbyopia
- Diabetes retinopathy
- Glaucoma
- Corneal abrasion or scarring; keratitis
- conjunctivitis
- Uveitis
- Iritis
- Retinal detachment
- Retinitis
- Eye trauma (Hyphema)
- Migraine
- Malignancy and tumor (Brain tumor, Lung cancer metastasis   ,Leukemia)
- Optic neuritis
- Cerebrovascular disease (TIA, stroke)
- Vasculitis (Temporal arteritis,SLE)
- High blood pressure
- Medication

# Epidemiology and Demographics
Patients of all age groups may develop blurred vision.By the age of 65,approximately one in three people  has some form of vision-reducing eye disorder .

# Risk Factors
Risk factors in the development of blurred vision include Genetic,Nutritional,Family history,Diabetes mellitus,Age,Hyperlipidemia,Hypertension,Toxins, Exposure to ultraviolet light. 

# Screening
- According to the American Diabetes Associations patients with type 1 and type 2 diabetes should have comprehensive eye examination within 5 years after the onset of diabetes and at the time of diagnosis ,respectively.  The eye examination should be considered at least annually thereafter.
- There is insufficient evidence to recommend routine screening for Glaucoma. USPSTF suggests that patients at increased risk, especially African Americans and older adults, talk to their primary care clinician or eye care specialist for advice about glaucoma screening.
- The USPSTF. recommends annual screening for adults aged 40 years or older and for those who are at increased risk for high blood pressure. Persons at increased risk include those who have high-normal blood pressure (130 to 139/85 to 89 mm Hg), those who are overweight or obese, and African Americans. Adults aged 18 to 39 years with normal blood pressure (<130/85 mm Hg) who do not have other risk factors should be re-screened every 3 to 5 years.

# Natural History, Complications, and Prognosis
Prognosis of blurred vision depends on the underlying cause.

# Diagnosis
There are no established criteria for the diagnosis of blurred vision.
The diagnosis of blurred vision is based on taking detailed medical history and eye examination.Patient Should be asked about the onset, duration, associated symptoms and whether blurred vision is bilateral or unilateral.
History and Symptoms
- The common symptoms which accompany blurred vision include Redness of the eye,Eye pain,Epiphoria,Headache,Photophobia,Halos,Nausea,Polydipsia and polyuria,Dizziness,Numbness.
Physical Examination
- Eye examination of patients with blurred vision includes Visual acuity test,Visual fields examination,Slit lamp,Ophthalmoscopy,Tonometry,Angle Test (Gonioscopy)
- The presence of suddenhemiplegia ,abnormal gait,ataxia and dysarthria is diagnostic of cerebrovascular accident.
Laboratory Findings
- Patients with systemic disorders should have appropriate testing.
- An elevated concentration of blood sugar and Hemoglobin A1C  is seen in blurred vision due to diabetes mellitus.
- Urinalysis and renal function testing should be considered in patients with high blood pressure.
- Antinuclear antibodies and elevated ESR are associated with SLE and vasculitis. 
- CBC with differential count and other tests are needed in some cases( Leukemia, Multiple myeleoma)
CT scan
- CT scan of brain may be helpful in diagnosis of mass occupying lesions or Ischemic and hemorrhagic stroke.
MRI
- A magnetic resonance imaging (MRI) study of the brain and orbits  may confirm inflammation of the optic nerve.

# Treatment
Depends upon the cause, underlying disorders should be addressed.
- Patients with refractive errors and presbyopia can be  treated with Corrective lenses and eyeglasses.
- Supportive therapy for hyphema includes raising the head of the bed, wearing eye shield and cut back on physical activity.
- There is no treatment for dry macular degeneration.Patients with wet macular degeneration may be treated with Anti-VEGF medications or Photodynamic therapy which help stop the growth of new blood vessels.

## Medical Therapy
- Medical therapy of diabetic retinopathy include direct injections or intravitreal administration of  anti-inflammatory and antiangiogenesis agents(anti-VEGF drugs  ) which are widely used pharmacotherapy to effectively treat DR and diabetic macular edema (DME).
- Laser treatment  is an option in treatment of diabetic retinopathy.
- Pharmacologic medical therapy with eye drops is recommended among patients with Glaucoma.  
- The mainstay of treatment in infectious cases include antibacterial, antiviral or anti parasite agents.  
- Patients with uveitis, iritis and optic neuritis can be treated with corticosteroids.   
- Patients with temporal arteritis are treated with high dose of corticosteroids.
- Treatment of high blood pressure is medical therapy with anti hypertensive medications.

## Surgery
- Surgical intervention like LASIK is commonly used to correct a refractive error.
- Laser treatments and surgical procedures for presbyopia haven't yet been well studied .
- Surgery is the mainstay of treatment for cataract and retinal detachment.
- Vitrectomy is used in treatment of Diabetic retinopathy.
- Different types of surgeries  to treat glaucoma are Trabeculoplasty ,Iridotomy and Trabeculectomy.

## Primary Prevention
Preventive measures in developing diabetic retinopathy include a healthy lifestyle, controlling hypertension, stringent lipid control and periodic ophthalmic examinations. . Studies have confirmed an increased risk of AMD among smokers; so,  smokers should be encouraged to quit.

## Secondary Prevention
- Effective measures for thesecondary prevention of blurred vision due to refractive errors is early detection and treatment of refractive errors in school vision programs.
- Secondary Prevention of Atherosclerotic Cardiovascular Disease includes lifestyle interventions,weight management,anti hypertensive agents, stain therapy,Anti- platelet Therapy,diabetes treatment and Cigarette/Tobacco Cessation.