Objective: To study the distribution of septo-optic dysplasia (SOD) and optic nerve hypoplasia (ONH) in the Greater Manchester and Lancashire (GM&L) region of Northwest England, and to analyze occurrence by location and over time. Study design: A population-based incidence study was undertaken for cases of SOD/ONH from GM&L. Standardized incidence ratio (SIR) for each district, relationships between SIRs and possible geographically varying risk factors, and spatial and space-time clustering were analyzed. Results: Eighty-seven cases had a confirmed diagnosis of ONH/SOD giving an incidence of 10.9/100,000 per year in GM&L. SIRs ranged widely but were significantly elevated (lower confidence limit > 100) in three districts: 167%, 192%, and 198%, respectively. All three were high population density, inner-city locations. SIRs were significantly correlated with higher rates of unemployment (r=0.49, P= .01), dependent children in nonearning households (r= 0.47, P= .02), underage conceptions (r= 0.46, P= .02), and underage pregnancies (r=0.44, P= .03). There was no evidence of spatial or space-time clustering. Conclusions: The incidence of ONH/SOD in GM&L was higher than that reported elsewhere. Cases were more common in areas that had higher unemployment and teenage pregnancy rates. Objective: To study the distribution of septo-optic dysplasia (SOD) and optic nerve hypoplasia (ONH) in the Greater Manchester and Lancashire (GM & L) region of Northwest England, and to analyze occurrence by location and over time. -based incidence study was undertaken for cases of SOD / ONH from GM & L. Standardized incidence ratio (SIR) for each district, relationships between SIRs and possible geographically varying risk factors, and spatial and space-time clustering were analyzed. Results: Eighty-seven cases had a confirmed diagnosis of ONH / SOD giving an incidence of 10.9 / 100,000 per year in GM & L. SIRs ranged widely but were significantly elevated (lower confidence limit> 100) in three districts: 167%, 192%, and 198%, respectively . All three were high population density, inner-city locations. SIRs were significantly correlated with higher rates of unemployment (r = 0.49, P = .01), dependent children in nonearning households conceptions (r = 0.46, P = .02), and underage pregnancies (r = 0.44, P = .03). There was no evidence of spatial or space-time clustering. Conclusions: The incidence of ONH / SOD in GM & L was higher than that reported elsewhere. Cases were more common in areas that had higher unemployment and teenage pregnancy rates.