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Tono-pen measurement of intraocular pressure (IOP) under topical anaesthesia in full term normal newborns.The IOP measurements were taken using Tono-pen XL tonometer under topical anaesthesia in 150 newborns (300 eyes) within 24h after birth, over a period of three months, in a university hospital. Gender, gestation period, mode of delivery and birth weight of newborns were noted from medical records.There were 70 males and 80 females. All babies were Malays. The IOP measurements were taken between 12 and 24h after birth. The gestation period of babies ranged between 37 and 41 weeks; 118 babies were delivered by spontaneous vaginal delivery and 32 by caesarian section. The birth weight of babies ranged between 2.1 and 4.3kg. The mean IOP of 300 eyes was 15.99±2.79mmHg (range 8-22). There was no statistically significant difference of mean IOP and gender, laterality of eye, type of delivery, gestation age, or birth weight of newborns.The IOP in full term normal newborns was 16mmHg. Tono-Pen appears to be ideal instrument for taking IOP in newborns because of its small size and easy handling.

To determine the asymmetry in the sympathetic activity in the eyes as indicated by intraocular pressure (IOP).In a prospective cross sectional study, the IOP in 150 newborns, 80 young adults and 159 old people was measured with Tono-Pen under topical anaesthesia.The mean IOP in the newborns was 16.16mmHg in right eye and 15.79mmHg in left eye; in young adults 15.04mmHg in right eye and 14.71 in left eye; in old people 15.16 in right eye and 15.03 in left eye. A statistically significant higher IOP was noted in the right eye in the newborns (P=0.03) and in young adults (P=0.02), but not in the old people (P=0.26). The higher IOP in the right eye indicates the lowered sympathetic activity in that eye.We hypothesize that the sympathetic asymmetry in the bilaterally placed organs helps to establish the dominant pattern of the organ in the body.