Initial Parafoveal Versus Peripheral Scotomas in Glaucoma: Risk Factors and Visual Field Characteristics

Objective: To assess risk factors for an initial parafoveal scotoma (IPFS) compared with an initial nasal step (INS) in glaucoma. Design: Retrospective, observational study. Participants: Sixty-nine patients with glaucoma with an isolated IPFS and 53 patients with an isolated INS. Methods: On the basis of 2 reliable, consistent 24-2 Swedish interactive threshold algorithm standard visual fields (VFs), 2 groups of patients with glaucoma were studied: those with an IPFS in 1 hemifield (>= 3 adjacent points with P<5% within the central 10 degrees of fixation, >= 1 point with P<1% lying at the innermost paracentral points, and no VF abnormality outside the central 10 degrees) and those with an INS in 1 hemifield (>= 3 adjacent points with P<5% in the nasal periphery outside 10 degrees of fixation, the nasal-most point with P<1%, and no VF abnormality within the central 10 degrees). Clinical characteristics and systemic factors were recorded from charts and compared between the 2 groups. Main Outcome Measures: Maximum untreated intraocular pressure (IOP), disc hemorrhage (DH) detection during follow-up, systemic risk factors, and VF mean deviation (MD) and pattern standard deviation (PSD). Results: Maximum untreated IOP (21.6 +/- 4.5 vs. 28.3 +/- 9.6 mmHg; P<0.001) was significantly lower, and frequency of DH detection (44% vs. 17%; P<0.001) and systemic risk factors (hypotension, migraine, Raynaud's phenomenon, and sleep apnea; 16%, 23%, 24%, and 9% vs. 0%, 4%, 9%, and 0%; P<0.001, 0.002, 0.025, and 0.030, respectively) were significantly higher in patients with an IPFS than in patients with an INS. There were no significant differences in age, gender, family history of glaucoma, refractive error, central corneal thickness, and disc area between the 2 groups (all P<0.1). Mean deviation was similar between the 2 groups (P<0.346), but PSD was significantly greater in the IPFS group than in the INS group (P<0.043). Conclusions: Eyes with an IPFS differ from those with an INS. These findings may help clinicians identify patients at higher risk of early central field loss.