Light perception describes the ability to perceive the difference between light and dark, or daylight and nighttime. Those persons with severely reduced vision described as having only "light perception" have no more sight than the ability to tell light from dark. A "blind" person may be considered photoreceptive, that is, able to distinguish light and the direction it is coming from, and may be able to see the outlines of large objects.

Surprisingly, blindness rarely means total absence of light perception. Most definitions of blindness are based on measurement of visual acuity (the ability to read letters at a certain distance) and assessment of the ability of the person to carry out tasks needing vision. Various scales have been developed to describe the extent of vision loss and define "blindness." Total blindness is the complete lack of form and visual light perception and is clinically recorded as "NLP," an abbreviation for "no light perception."

The leading causes of blindness in the United States are cataracts (see Diagnostic Code: 6027 Cataracts of any type); glaucoma (see Diagnostic Code: 6012 Angle-Closure Glaucoma); and age-related macular degeneration. Proliferative diabetic retinopathy (see Diagnostic Code: 7913 Diabetes mellitus) contributes as one of the chief causes of blindness. In addition, loss of vision may develop from severe eye infections (staphylococcal endophthalmitis), or complications of eye surgery.

Any ophthalmic disorder may result in gradual loss of vision. In cases where vision is limited to light perception, there is an inability to see hand movements at about three feet.

Ophthalmic examinations and tests usually include: external examination; visual acuity; visual fields; ophthalmoscopy; slit lamp; angiography; and ultrasonography.

Recognition and treatment of the early stages of diseases that cause blindness may slow their progress to legal blindness. Low-vision aids such as hand magnifiers, and electronic reading systems may be of assistance.

The goal of rehabilitation is to lead as normal a life as possible.Early referral to rehabilitation agencies for training and re-education is essential. Mobility training, possible use of guide dogs, learning Braille, or use of auditory aids may be considered. Counseling for body image disturbance related to loss of vision may be helpful.

• Consider entitlement to ancillary benefits if Veteran meets eligibility criteria (38 CFR 3.155(d)(2)).

• May be entitled to special monthly compensation where the Veteran has a single service-connected disability rated as 100% with additional service-connected disability or disabilities independently ratable at 60% or more, which are separate and distinct from the 100% service-connected disability and involves different anatomical segments or bodily systems. See  38 CFR 3.350(i)(1) – Special Monthly Compensation (SMC).

• Consider entitlement to specially adapted housing under 38 U.S.C. 2101(a)(2)(A)(i) if there is visual impairment to the degree specified in 38 CFR 3.809(b)(2).

• The veteran, spouse, surviving spouse or parent will be considered in need of regular aid and attendance if he or she is blind or so nearly blind as to have corrected visual acuity of 5/200 or less, in both eyes, or concentric contraction of the visual field to 5 degrees or less (38 CFR 3.351(c)(1)).

• Consider entitlement to automobile allowance and/or automobile adaptive equipment if there is visual impairment to the degree specified in 38 CFR 3.808(b)(3).

• Review for entitlement to special monthly compensation under 38 CFR 3.350.