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A 35-year-old normally pigmented man underwent monocular hemifield visual-evoked potential examinations that indicated a lack of normal decussation of nasal paramacular retinogeniculate fibers in the optic chiasm. We studied effects of this anomaly on ocular motility using electro-oculography and the magnetic search-coil technique. The patient exhibited horizontal congenital nystagmus with a predominantly positive exponential waveform. Horizontal smooth pursuit and optokinetic nystagmus were consistently reversed, independent of eye position in the orbit. Vertical tracking was uniformly normal. Horizontal vestibulo-ocular reflexes recorded in the dark during passive rotation exhibited normal gain and phase, whereas rotation recorded in the light reduced gain. Although active head movements reversed horizontal vestibulo-ocular reflexes, vertical vestibulo-ocular reflexes in light and darkness were normal. Our study suggested an association between a lack of normal decussation of retinal fibers in the optic chiasm, and reversed visual tracking and congenital nystagmus.

To understand better the source of conjunctival bacteria in neonates, we studied 106 infants immediately after birth before any eyedrops were applied. The 50 infants delivered by cesarean section had significantly fewer species (0.50 +/- 0.85 vs 1.84 +/- 1.33) and colony forming units (272 +/- 1,019 vs 1,790 +/- 3,779) cultured per subject than the 56 infants delivered vaginally. In infants delivered by cesarean section within three hours of membrane rupture, 24 of 30 (80%) of the conjunctival cultures were sterile, while the rest bore a few cutaneous bacteria (0.23 +/- 0.50 species and 2 +/- 9 colony forming units per subject). The conjunctivae of infants delivered vaginally bore significantly more bacteria characteristic of vaginal flora: microaerophilic as Lactobacillus or truly anaerobic as Bifidobacterium. Neonates delivered by cesarean section more than three hours after membrane rupture showed a bacteriologic flora mixture quantitatively and qualitatively midway between those two groups. Infants delivered by cesarean section within three hours of membrane rupture may not need prophylactic eyedrops because of the type and scarcity of conjunctival bacteria.