Central retinal vein obstruction and axial length. The axial lengths of 24 consecutive adult eyes with unilateral central retinal vein obstruction (CRVO) were compared with those of contralateral unaffected eyes and those of a control population. The lengths of the two eyes of persons with a unilateral CRVO were not significantly different. By contrast, eyes of persons with CRVO averaged 0.67 mm (approximately 2 diopters) shorter than their control counterparts (P = .03). This anatomic difference may be a factor in the development of CRVO. 