Nyctalopia: Blinded By The Night

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If navigating your route while driving at night has become too challenging for comfort, you may be experiencing nyctalopia. Characterized as impairment in night vision, nyctalopia is a symptom of a number of underlying conditions. Diagnosing the condition that is causing your declining ability to see adequately after dark will determine whether or not treatment options are available.

Signs of Nyctalopia

Night blindness does not mean a complete absence of vision at night. Night blindness indicates a diminished capacity to adjust to changes in lighting and the inability to visualize things clearly in the dark. The signs of nyctalopia are especially evident when attempting to drive at night. You may have observed the following signs the last time you took to the road after the sun went down:

• The lines that mark the lanes of the road were not visible.
• Oncoming headlights seemed glaringly bright
• Taillights and traffic lights appeared to have halos.
• Things seemed blurry, and street signs were not easy to read.
• You had difficulty identifying objects in the road ahead or on the roadside.

These signs tend to appear worse to the sufferer when the nighttime navigation takes place during rainy weather. Whether conditions are dry or wet, the signs can become overwhelming and reduce a driver's confidence.

Curable Conditions

Your nyctalopia may be caused by a condition that can be corrected. Three of these conditions include the following:

• Myopia, more commonly known as nearsightedness
• Cataracts
• Vitamin A deficiency

Visual deficits caused by myopia can be improved with corrective lenses or with refractive surgery, such as the LASIK procedure. Cataracts ultimately lead to blindness. Pursuing a cataract surgery procedure can prevent this outcome and restore your overall vision, including night vision. By supplementing your diet with vitamin A and lutein, another valuable nutrient for maintaining eye health, you will correct your nutritional imbalance and help to reduce the chance of developing macular degeneration, another disease of the eye that results in vision loss.

Incurable Conditions

The retina, which is the membrane located at the back of the eye, is responsible for receiving light signals from its photoreceptors, which are called rods. The signals are then processed by the retina and transmitted to the brain through the optic nerve. When the retina sustains degeneration, night blindness results. Such degenerative conditions are usually incurable. One incurable condition that causes night blindness in a rare congenital disorder called retinitis pigmentosa.

Other causes of nyctalopia that result from degeneration of the retina occur as part of the aging process. Such age-related degeneration typically strikes after the age of 40 and includes the following changes:

• With age, the number of rods dissipates by one-third.
• Cholesterol accumulates at the ducts of the Bruch's membrane, blocking off the supply of nutrients to the retina.
• There is a reduction in the level of rhodospin, a pigment that enables the rods to sense light and adapt to changes in lighting.

Other Causes

Some medications, including certain heart medications, glaucoma medications and bile acid sequestrants, carry the potential side effect of diminished night vision. Be sure to alert your physician and your optometrist or ophthalmologist of all prescription and over-the-counter medications that you are taking, and remember to mention any herbal and nutritional supplements that you take as well.

Coping with Incurable Nyctalopia

If you are experiencing a decrease in your night vision, especially while driving after dark, schedule an appointment with your optometrist for a vision exam and an evaluation of your ocular health. If the reason is determined to be incurable, you will have to make some lifestyle changes, such as no longer driving at night, to ensure your safety and the safety of others. You can also make adjustments to cope with your night blindness, such as installing nightlights in your home to lighten your path from room to room and using the flashlight application on your smartphone to illuminate a visual field in darkened settings.

For more information, contact Complete Family Vision Care or a similar location.

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10 December 2015