The most common symptom associated with uncorrected myopia is blurred distance vision. In simple myopia and degenerative myopia, the distance blur is constant. In nocturnal myopia, the distance vision is blurred only in dim illumination or in dark conditions.
In pseudomyopia, the blurred distance vision may be constant or intermittent with greater distance blur occurring after near work.
Blurred distance vision in induced myopia can vary from transient (lasting a few hours) to constant, depending upon the particular agent or condition causing it.
With the exception of pseudomyopia and some forms of induced myopia, asthenopic symptoms are not characteristic of myopia. If asthenopia is present in a patient with myopia, it is usually due to some other cause, such as astigmatism, anisometropia, an accommodative dysfunction, or to a vergence disorder. Children with simple myopia are often unaware that they have reduced distance vision until they discover that other children see better than they can.
For example, many school children first notice that they cannot read the chalkboard as well as their classmates. For others who never report a problem, the poor distance vision is first detected during vision screening or comprehensive eye and vision examination. The primary sign of myopia is reduced unaided distance visual acuity, which can be corrected to standard or near-standard levels with the appropriate minus power optical correction. The uncorrected visual acuity level and the degree of uncorrected myopia are highly correlated .104-106 In nocturnal myopia, the result of retinoscopy in a dark room may be shifted in the minus direction, compared with the standard manifest refraction. Patients who have nocturnal myopia often complain of difficulty driving at night and/or blurred distance vision at night.
Patients with pseudomyopia frequently have fluctuations in distance visual acuity that correspond to fluctuations in accommodation. These fluctuations in accommodation may be observable as variations in visual acuity and retinoscopic reflex and, sometimes, changes in pupil diameter.
