What are the symptoms of night blindness?

Symptoms of Night Blindness

Night blindness (nyctalopia) primarily manifests as difficulty seeing under conditions of decreased illumination, with patients experiencing impaired vision in dim light or darkness that significantly affects their ability to navigate and function in low-light environments. 1

Core Visual Symptoms

The hallmark symptom is reduced visual function in darkness or dim lighting conditions, which represents a failure of dark adaptation due to impaired rhodopsin synthesis in the retinal photoreceptors. 1 This manifests as:

• Difficulty seeing in dimly lit environments such as at dusk, nighttime, or in darkened rooms 1
• Impaired ability to navigate in low-light conditions, including difficulty walking in dark spaces 1
• Poor vision when transitioning from bright to dark environments, reflecting abnormal dark adaptation 2

Functional Impairments

Patients with night blindness experience specific functional difficulties that impact daily activities:

• Problems navigating steps or curbs in reduced lighting 1
• Tripping over objects on the floor when illumination is poor 1
• Difficulty identifying familiar people across a room, particularly in crowds or dimly lit spaces 1
• Reduced visual function in visually crowded environments such as shopping malls where lighting may be variable 1

Associated Visual Symptoms

Night blindness may present alongside other visual complaints depending on the underlying cause:

• Lack of eye contact in children with congenital conditions causing night blindness 1
• Light sensitivity (photophobia) in some cases 1
• Failure to master color identification in children with certain genetic disorders 1
• Nystagmus may be noted by parents and caregivers in children with congenital or early-onset vision loss involving the anterior visual pathway 1

Severe Manifestations in Vitamin A Deficiency

When night blindness results from vitamin A deficiency, progressive symptoms may develop if untreated:

• Night blindness is the earliest clinical sign of vitamin A deficiency, occurring before other ocular manifestations 1, 3
• Bitot spots (grey/white, foamy appearance on the conjunctiva) may develop 1
• Xerophthalmia (dryness of the conjunctiva and cornea) in advanced cases 1, 3
• Keratomalacia (corneal softening and ulceration) represents severe progression that can lead to permanent blindness 1, 3
• Increased susceptibility to infections, particularly respiratory tract infections, accompanies vitamin A deficiency 1

Pediatric Presentation

In children with conditions causing night blindness, specific behavioral signs may be observed:

• Oculodigital sign (pushing on eyes with fingers) in children with severe visual impairment such as Leber congenital amaurosis, which is a risk factor for keratoconus and periorbital fat atrophy 1
• Difficulty with visual tasks that require adaptation to changing light conditions 1

Important Clinical Caveats

Night blindness can occur without apparent organic eye disease in cases of essential or epidemic night blindness caused by vitamin A deficiency, and may progress to permanent blindness if not treated promptly with vitamin A supplementation or vitamin A-containing foods. 4 The condition is strongly associated with low serum vitamin A concentration, abnormal conjunctival impression cytology, and impaired dark adaptation. 5