Dear Editor

I read with great interest the article by Isenberg et al.[1] on "A double application approach to ophthalmia neonatorum prophylaxis." The authors deserve to be commended for their pioneering interest in childhood blindness. There are certain points that I would like to clarify and supplement with regard to their study.

1. The authors have mentioned that only babies born by a vaginal delivery were studied, since the eyes of babies delivered by caesarean section were previously proved to be nearly always sterile. This would result in a gross underestimation of the incidence of ophthalmia neonatorum in this study, for the following reason.

By convention, ophthalmia neonatorum is defined as conjunctivitis arising within one month after birth.2 Hence, some of these conjunctival infections could originate from sources other than the maternal vaginal and cervical flora. In fact, some cases of ophthalmia neonatorum especially those caused by Staphylococcus aureus could have originated at home, as previously reported by the authors themselves.2 In the same study, no significant difference in the frequency or type of infection was seen among the infants delivered vaginally or by caesarean section.[2]

Other authors, too have made similar observations. Krohn et al.[3] have found some cases of ophthalmia neonatorum to have been acquired from the infants' nasopharyngeal passages or from their care givers after birth. Verma et al.[4] in a prospective study from India, found no correlation between the microbiology of the conjunctival swabs of the infected eyes (Staphylococcus aureus was the commonest isolate) and the vaginal and cervical swabs of the mothers (Escherichia coli was the commonest isolate). They concluded that most of the cases of ophthalmia neonatorum were acquired postnatally. In the light of these previously reported studies, I feel that exclusion of cases that were delivered by caesarean section was not warranted and weakens the power of this study. The efficacy of the second drop of povidone iodine was not tested on a significant proportion of the cases of ophthalmia neonatorum (those cases affecting the babies delivered by caesarean section).

2. It would be relevant to note the percentage of ophthalmia neonatorum cases with neonatal dacryocystitis due to congenital nasolacrimal duct obstruction in this series. Such cases obviously would not have benefited from a second drop of povidone-iodine.

3. The Indian study by Verma et al. l4 found a seasonal incidence to ophthalmia neonatorum with two peaks: in the February and May-June, in most probability due to the monsoon and the hot tropical climate with the attendant eye seeking flies. It would be interesting to know whether any such seasonal variation was noted in this study that was carried out in Kenya, a country with a hot tropical climate, like India. If so, the efficacy of the second drop could be investigated again during such peaks.

Vasumathy Vedantham MS, DNB, FRCS
Retina - Vitreous Service, Aravind Eye hospital and Postgraduate Institute of Ophthalmology
1, Anna Nagar, Madurai - 625 020, Tamilnadu, India.
Telephone: 0452-2532653
Fax: 0452-2530984
Email: drvasumathy@yahoo.com

References

1. Isenberg SJ, Apt L, Signore M Del, Gichuhi S, Berman NG. A double application approach to ophthalmia neonatorum prophylaxis. Br J Ophthalmol 2003;87(12): 1449-1452.

2. Isenberg SJ, Apt L,Wood M. A controlled trial of povidone-iodine as prophylaxis against ophthalmia neonatorum. N Engl J Med 1995;332:562-6.

3. Krohn MA, Hillier SL, Bell TA, Kronmal RA, Grayson JT. The bacterial etiology of conjunctivitis in early infancy. Am J Epidemiol 1993;138:326-32.

4. Verma M, Chhatwal J, Vareghese PV. Neonatal conjunctivitis: a profile. Indian Pediatr 1994;31(11): 1357-61.