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Inferior parafoveal scotomas progress away from point of fixation
Superior and inferior initial parafoveal scotomas showed similar patterns of progression, but inferior scotomas migrated farther from fixation, according to a study.
The retrospective, observational study included 80 eyes of 80 patients with initial parafoveal scotomas.
Investigators enrolled patients with an initial parafoveal scotoma in one hemifield, according to 24-2 SITA standard automated perimetry. For cross-sectional analysis, investigators used the pattern standard deviation of the first 10-2 visual field tests to assign eyes to subgroups. Longitudinal analysis was performed with 10-2 pattern deviation map values to evaluate the locations of significant progression points.
Study results showed that initial parafoveal scotomas in the superior hemifield had an arcuate pattern that deepened about 3° to 5° above fixation. Scotomas became elongated toward the physiologic blind spot and gravitated toward the nasal periphery.
Initial parafoveal scotomas in the inferior hemifield showed a similar pattern but were slightly farther from the point of fixation, the authors said.
Perspective
Back to TopIn the retrospective study by Su et al, the authors characterized, in detail, the appearance of paracentral defects (ie, defects within 6° of the foveal center) and pattern progression of by using serial 10-2 testing (ie, more detailed test of the central 10°). They found that when progression occurred, the scotoma enlarged in a pattern that followed the papillomacular bundle. These findings indicate that ganglion cell/axonal susceptibility is not uniform and can be predicted by highly conserved anatomic or physiologic aspects of the axons within the optic nerve or the cell bodies and axons from their blood supply or other supporting cells. The fact that progression occurs along a characteristic pattern gives greater hope that the underlying pathophysiology could be identified and perhaps interrupted. Additionally, this study highlights that patients with glaucomatous damage can have significant loss of central vision that has functional/symptomatic effects on activities of daily living, such as reading. In patients with paracentral defects, central 10-2 visual field testing could be very helpful.