Refraction and keratometry in 40 week old premature (corrected age) and term infants

Abstract

Aim: To compare refraction and keratometry readings between premature and term babies at 40 weeks' postconceptional age (PCA), and the possible effect of birth weight (BW) and gestational age (GA) on ocular parameters. Methods: 33 preterm babies hospitalised in the neonatal unit between January and March 2002 were matched with 33 term babies born within the same period and hospitalised in the same unit. The preterm group underwent funduscopy at 4-5 weeks after delivery. Ophthalmic examination at 40 weeks' PCA included cycloplegic retinoscopy, funduscopy, and keratometric measurements. Mean and standard deviation of refraction, astigmatic power (plus cylinder), axis of astigmatism, and keratometric reading were calculated and compared between groups and correlated with BW and GA in the premature babies. Results: Retinopathy of prematurity (ROP) stage 1 or 2 was noted in 88% of the premature babies on the first funduscopy examination, but only in 36% by the corrected age of 40 weeks. Statistically significant between groups differences were found for cycloplegic refraction (p = 0.02 for both eyes) and keratometry (p = 0.001 for both eyes). GA and BW had no impact on the refractive and keratometric findings in the preterm babies. Conclusions: Babies with mild ROP at the corrected age of 40 weeks have mild hypermetropia compared to the moderate hypermetropia found in term babies (a difference of 50%), and they have higher and steeper keratometric values. The greater corneal curvature may contribute to the development of myopia. Ophthalmologists and parents need to be aware of the possibility of visual dysfunction already very early in life even in relatively older premature infants.

Effects of Birth Weight on Anterior Segment Measurements in Full-Term Children Without Low Birth Weight by Dual-Scheimpflug Analyzer

“…7,24,25 In children with ROP, shallower anterior chambers, steeper corneal curvatures, and shorter axial lengths were shown to be related to gestational age and birth weight. 7,11,12,24,25 In our study, as expected, we found no relationships between gestational age and any of the studied anterior segment parameters. Because our study subjects had gestational ages >37 weeks and intrauterine eye growth had nearly completed after 37th week of gestation, the range of gestational ages may not have been sufficient to reveal significant relationships between gestational age and anterior segment structures.…”

“…Our study population comprised preschool children, born at term, with birth weight of >2500 g. Previous studies had reported that prematurity and low birth weight have significant effects on the anterior segment, particularly in premature infants with/without ROP (Retinopathy of Prematurity). 7,11,12,24,25 …”

“…ROP, itself, appears to influence the growth of the eye during the early stages of development. Most of the studies investigating the relationship of birth weight and gestational age with ocular biometric parameters were generally performed on premature infants with ROP 8,11,12 or on infants at high risk for ROP. 7,24,25 In children with ROP, shallower anterior chambers, steeper corneal curvatures, and shorter axial lengths were shown to be related to gestational age and birth weight.…”

“…4 Pre-term babies with low birth weight may experience retinopathy of prematurity (ROP), myopia, strabismus, amblyopia, and cerebral visual impairment. 5,6 While the association of birth weight with anterior segment parameters have been investigated, those studies had usually been performed on preterm, low birth weight (especially those with ROP) infants in the early weeks of life [7][8][9][10][11][12][13] or on multi-ethnic children. 14 Ethnicity is a factor with a potentially great impact on both birth and anterior segment parameters.…”

Problemas oftalmológicos mais freqüentes e desenvolvimento visual do pré-termo extremo

“…They eye always tends to emetropia (with no refractive errors) and, in order to compensate for the smaller APD at birth the cornea has a high power of refraction (47.6 diopters), which reduces progressively as the eye grows, reaching 42.5 diopters in adulthood. 1,2 Children born to full term have a slight tendency to hypermetropia. Population studies show that this hypermetropia tends to increase until 7 years of age and then there is a tendency to myopization until adulthood.…”