what are the symptoms of blurred eyes and Diabetic retinopathy

Blurred vision refers to a lack of sharpness of vision resulting in the inability to see fine detail. Blurred vision may result from abnormalities such as nearsightedness, farsightedness, presbyopia, or astigmatism that can be improved with corrective lenses (eyeglasses), or it may signal the presence of eye disease.

Blurry vision may be experienced in one eye or both eyes, depending upon the cause. Blurred vision can also be a symptom of numerous conditions that do not directly involve the eye, such as migraine or stroke. Several medications may also lead to temporary blurring of vision as a side effect. Sometimes, blurred vision is associated with other symptoms, depending upon its cause, including headache, sensitivity to light, or redness and irritation of the eyes.

Causes

There are many causes of blurred vision:

• Refractive errors: Uncorrected refractive errors like myopia, high hypermetropia, and astigmatism will cause distance vision blurring. It is one of the leading causes of visual impairment worldwide. Without associated amblyopia, visual blur due to refractive errors can be corrected to normal using corrective lenses or refractive surgeries.
• Presbyopia due to physiological insufficiency of accommodation (accommodation tends to decrease with age) is the main cause of defective near vision in the elderly. Other causes of defective near vision include accommodative insufficiency, paralysis of accommodation, etc.
• Pseudomyopia due to accommodation anomalies like accommodative excess, accommodative spasm, etc., causes distance vision blurring.
• Alcohol intoxication can cause blurred vision.
• The use of cycloplegic drugs like atropine or other anticholinergics causes visual blur due to paralysis of accommodation.

  

• Cataracts: Cloudiness over the eye’s lens causes blurring of vision, halos around lights, and sensitivity to glare. It is also the main cause of blindness worldwide.
• Glaucoma: Increased intraocular pressure (pressure in the eye) causes progressive optic neuropathy that leads to optic nerve damage, visual field defects, and blindness. Sometimes glaucoma may occur without increased intraocular pressure also. Some glaucomas (e.g., open-angle glaucoma) cause a gradual loss of vision, while others (e.g., angle-closure glaucoma) cause sudden vision loss. It is one of the leading causes of blindness worldwide.
• Diabetes: Poorly controlled blood sugar can lead to temporary swelling of the eye’s lens, resulting in blurred vision. While it resolves if blood sugar control is reestablished, repeated occurrences promote the formation of cataracts (which are not temporary).
• Retinopathy: If left untreated, any retinopathy (including diabetic retinopathy, hypertensive retinopathy, sickle cell retinopathy, etc.) can damage the retina and lead to visual field defects and blindness.
• Diabetic retinopathy, also known as diabetic eye disease (DED), is a medical condition in which damage occurs to the retina due to diabetes mellitus. It is a leading cause of blindness in developed countries. Diabetic retinopathy affects up to 80 percent of those who have had diabetes for 20 years or more. At least 90% of new cases could be reduced with proper treatment and monitoring of the eyes. The longer a person has diabetes, the higher his or her chances of developing diabetic retinopathy. Each year in the United States, diabetic retinopathy accounts for 12% of all new cases of blindness. It is also the leading cause of blindness in people aged 20 to 64.
  

  Signs and symptoms

  

The first stage, called non-proliferative diabetic retinopathy (NPDR), has no symptoms. Patients may not notice the signs and have 20/20 vision. The only way to detect NPDR is by fundus examination by direct or indirect ophthalmoscope by a trained ophthalmologist; fundus photography can be used for objective documentation of the fundus findings, in which microaneurysms (microscopic blood-filled bulges in the artery walls) can be seen. If there is reduced vision, fluorescein angiography can show narrowing or blocked retinal blood vessels clearly (lack of blood flow or retinal ischemia).

Macular edema, in which blood vessels leak their contents into the macular region, can occur at any stage of NPDR. Its symptoms are blurred vision and darkened or distorted images that are not the same in both eyes. Ten percent (10%) of diabetic patients will have vision loss related to macular edema. Optical Coherence Tomography can show areas of retinal thickening due to fluid accumulation from macular edema.

In the second stage, abnormal new blood vessels (neovascularisation) form at the back of the eye as part of proliferative diabetic retinopathy (PDR); these can burst and bleed (vitreous hemorrhage) and blur the vision because these new blood vessels are fragile. The first time this bleeding occurs, it may not be very severe. In most cases, it will leave just a few specks of blood or spots floating in a person’s visual field, which may last for months.

These spots are often followed within a few days or weeks by a much greater leakage of blood, which blurs the vision. In extreme cases, a person may only be able to tell light from dark in that eye. It may take the blood anywhere from a few days to months or even years to clear from the inside of the eye, and in some cases, the blood will not clear. These types of large hemorrhages tend to happen more than once.

On funduscopic exam, a doctor will see cotton wool spots, flame hemorrhages, and dot-blot hemorrhages.

• Hypervitaminosis A: Excess consumption of vitamin A can cause blurred vision.
• Macular degeneration: Macular degeneration causes loss of central vision, blurred vision (especially while reading), metamorphopsia (seeing straight lines as wavy), and faded colors. Macular degeneration is the third main cause of blindness worldwide and is the main cause of blindness in industrialized countries.
• Eye infection, inflammation, or injury.
• Sjögren’s syndrome, a chronic autoimmune inflammatory disease that destroys moisture-producing glands, including the lacrimal gland, leads to dry eye and visual blur.
• Floaters: Tiny particles drifting across the eye. Although often brief and harmless, they may be a sign of retinal detachment.
• Retinal detachment: Symptoms include floaters, flashes of light across your visual field, or a sensation of a shade or curtain hanging on one side of your visual field.
• Optic neuritis: Inflammation of the optic nerve from infection or multiple sclerosis may cause blurring of vision. There may be pain while moving the eye or touching it through the eyelid.
• Stroke or transient ischemic attack
• Brain tumor
• Toxocara: A parasitic roundworm that can cause blurred vision.

  

• Bleeding into the eye
• Temporal arteritis: Inflammation of an artery in the brain that supplies blood to the optic nerve.
• Migraine headaches: Spots of light, halos, or zigzag patterns are common symptoms before starting the headache. A retinal migraine is when you have only visual symptoms without a headache.
• Reduced blinking: Lid closure that occurs too infrequently often leads to irregularities of the tear film due to prolonged evaporation, thus resulting in disruptions in visual perception.
• Carbon monoxide poisoning: Reduced oxygen delivery can affect many areas of the body, including vision. Other symptoms caused by CO include vertigo, hallucination, and sensitivity to light.

Other causes of blurred vision

• Bleeding Into the Eye
• Convergence Insufficiency
• Corneal Abrasion
• Eye Infection
• Foreign Body in the Eye
• Incorrect Eyeglass Prescription
• Lens Dislocation
• Medications
• Trauma to the Eye or Head

https://www.diabetesasia.org/magazine/category/diabetes-in-eye-care/