What Is Hemianopia (Hemianopsia)?

3. Causes of monocular hemianopia

The damage caused by a unilateral retinal or optic nerve disease may result in monocular hemianopia because they involve the pre-chiasmal visual pathway. A retinal detachment, for example, located nasally, would give a temporal field defect in one eye. Inversely, a temporal retinal detachment is manifested by a nasal field defect in the affected eye. However, a retinal detachment is more often characterized by an atypical hemianopia which extends beyond the midline due to the spatial distribution of the retinal photoreceptors.

Optic nerve compression can also cause monocular nasal or temporal hemianopia. The loss of visual field, in this case, may be progressive and visual acuity may still be preserved. Other features like pain and fluctuating visual loss may be described in this scenario. Temporal hemianopia in one eye has frequently been associated to the compression of optic nerve due to a lateral development of pituitary gland adenoma or benign tumors arising from the neighboring meningeal structures called meningiomas (64% and 8%, respectively).