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R. Hamilton, H. Mactier, M.S. Bradnam, C. Malcolm, D. McCulloch, J. Dudgeon; Oscillatory Potentials (OPs) in Premature and Term-Born Infants . Invest. Ophthalmol. Vis. Sci. 2003;44(13):599.
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Purpose: To describe the extent of oscillatory potentials (OPs) in the electroretinogram of term- and prematurely-born infants. Methods: Premature (N=40: no or mild ROP, N=31; threshold ROP requiring laser treatment, N=9) and term-born (N=10) infants were dark-adapted for at least 30 minutes, then had full-field ERGs recorded to brief white light flashes (11.3 scot cd s/m2) using a corneal electrode and amplifier bandpass of 30-300Hz. Responses were digitally high-pass filtered (3dB cut-off: 75Hz) to view any OPs. A noise criteria was applied to each recording to determine the minimum significant OP amplitude. ERGs were recorded on one occasion from the term-born infants during their first week of life and serially (1 to 6 recordings per infant) from the premature infants at postmenstrual ages (PMA) of 30 to 68 weeks, giving a total of 87 recordings. Results: OPs were evident in 1/10 (10%) of the term-born and in 43/77 (56%) of the premature infant recordings. Premature infant OPs were seen in 9/40 (22.5%) recordings made at PMAs between 30-37 weeks, but were seen in 34/37 (92%) of recordings made at PMAs over 38 weeks. OP2, OP3 and OP4 were the most robust peaks (seen respectively in 57%, 53% and 45% of premature infant ERGs). OP1 was only seen in six recordings, including that of the term infant with OPs, at PMAs from 34.7 to 55 weeks. OP5 was only seen in seven recordings, and was never evident before 48 weeks (PMA). The amplitudes of OP2, OP3 and OP4 increased exponentially, with rate of increase as follows: OP2>OP3>OP4. From term age, infants with treated ROP had relatively reduced OP amplitudes (on or below the 50th centile), particularly for OP2. Implicit times (IT) of OP2, OP3 and OP4 fell exponentially with age at approximately equal rates, and treated ROP infants showed no particular differences compared with no/mild ROP. Conclusions: OPs are evident in premature infants as early as 30 weeks PMA, but are not seen consistently until 38 weeks, some time after other ERG responses are reliably seen. OP2, OP3 and OP4 are the most robust peaks. OP5 is not evident until a PMA of 48 weeks or older. Full-term infants do not appear to have readily recordable OPs at birth, which suggests premature birth accelerates OP maturation. The faster growth rates of earlier OPs may reflect successive development of the neurotransmitter systems in the immature retina, which may be impaired by ROP.
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