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Development of astigmatism and anisometropia in preterm children during the first 10 years of life: a population-based study.
by Larsson EK, Holmström GEArticle Abstract:
OBJECTIVE: To assess the development of astigmatism and anisometropia to 10 years of age in preterm children, previously included in a population-based study on the incidence of retinopathy of prematurity. METHODS: Cycloplegic retinoscopies were performed in 198 preterm children at 6 months, 2(1/2) years, and 10 years of age. We analyzed the development of astigmatism of 1 diopter (D) or more and anisometropia of 1 D or more. RESULTS: The amount and prevalence of astigmatism declined between 6 months and 2(1/2) years of age and then remained stable. We found no difference in the course of astigmatism at different ages with regard to stage of retinopathy of prematurity. The amount of anisometropia increased, but its prevalence remained unchanged. Multiple regression analyses showed that astigmatism of 1 D or more at 2(1/2) years of age and cryotreated severe retinopathy of prematurity were risk factors for astigmatism at 10 years of age, and that anisometropia of 2 D or more at 2(1/2) years of age was a risk factor for anisometropia at 10 years of age. CONCLUSIONS: The development of astigmatism and anisometropia showed a similar course, regardless of stage of retinopathy of prematurity. The retinoscopy findings at 6 months of age were of no value in predicting astigmatism and anisometropia at 10 years of age, but the refraction at 2(1/2) years of age was. Retinoscopy at about 2(1/2) years of age in all preterm children may be useful for detecting astigmatism and anisometropia that will persist in children of school age.
Early Eye Exams Needed for Children Born Prematurely
By: Anonymous - Sat 11/25/2006 PMWhile earlier eye exams may catch more problems, they are not significantly correlated with abnormalities that persist at age 10, said Eva K. Larsson, M.D., Ph.D., and Gerd E. Holmström, M.D., Ph.D., both of Uppsala University Hospital here, in the November issue of the Archives of Ophthalmology.
Ophthalmologic studies of preterm children, defined as birth weight of 1,500 g or less, have found that these patients are at an increased risk of developing vision problems and need follow-up examinations.
To clarify the best age for these exams, the researchers performed retinoscopies looking at the back of the eye for refractive errors at ages six months, 2.5 years, and 10 years for 198 children born at 24 to 35 weeks gestational age.
The presence of astigmatism and anisometropia of two diopters or more at the 2.5-year exam significantly predicted the two conditions at age 10 in a multivariate analysis (both P<0.001) whereas their presence at the six-month exam did not.
"At two and one-half years of age, it is still possible to prevent amblyopia and prescribe eyeglasses to improve the development of vision," they wrote. "Therefore, we recommend that all preterm children have follow-up examinations at about this age."
"Recommendations for follow-up examinations must include all aspects of visual function, i.e., visual acuity, contrast sensitivity, and visual fields, as well as the refraction, strabismus, and perceptual problems. All preterm children should be included in such follow-up examinations for refractive error, irrespective of the [retinopathy of prematurity, or abnormal retinal blood vessel development] stage."
The investigators found that the overall prevalence of one diopter or more astigmatism (an unequal curve in one of the eye's refractive surfaces) dropped significantly between six months and 2.5 years of age (54.5% versus 27.3%, P<0.001) and then became stable out to 10 years (27.3% versus 20.7%, P=0.6).
Between the 2.5- and 10-year exams, 27 children lost their astigmatism and 14 developed a new case. Premature birth may predispose children to astigmatism due to disturbances in ocular growth such as changes in axial length, an increase in corneal curvature, a shallower anterior chamber, and a thicker lens.
The prevalence of anisometropia (a difference in refractive power between the two eyes that can lead to partial vision loss) was 7.6% at six months, 8.6 at the 2.5-year follow-up, and 8.1% at 10 years of age.
Anisometropia disappeared in some children and developed in others at about the same rate between the three exams, though the rate was more stable in those with a higher degree of anisometropia.
"The development of astigmatism and anisometropia showed a similar course, regardless of stage of retinopathy of prematurity," the researchers noted.
Of the initial cohort of 260 infants, 105 had retinopathy of prematurity (40.4%) and 28 were treated with cryotherapy for it (10.8%).
The prevalences of astigmatism (≥1 D) declined slightly in the children without retinopathy of prematurity (20.7% versus 13.2%) and those with mild retinopathy of prematurity (40.5% versus 21.4%) between the 2.5- and 10-year examinations. In the children with cryotreated severe retinopathy of prematurity, the prevalence increased during this period (43.5% versus 60.9%). However, none of the differences were statistically significant.
Cryotreatment, though, was a significant risk factor for astigmatism at 10 years of age (odds ratio 9.8, 95% confidence interval 3.2 to 30.3, P<0.001), in keeping with previous findings that it may affect long-term growth of the eye.
The prevalences for anisometropia at the 2.5- and 10-year follow-ups were as follows:
3.4% and 4.3% for children with no retinopathy of prematurity, 7.3% and 2.4% for those with mild retinopathy of prematurity, and 37.5% at both points for cryotreated severe retinopathy of prematurity.
"Therefore, apart from cryotreated severe [retinopathy of prematurity], the stage of [retinopathy of prematurity] should not be used as a criterion for follow-up examinations of refractive errors in our population," Drs. Larsson and Holmström concluded.
The study was supported by the Stiftelsen Synfrämjandets Foundation for Research and the Crown Princess Margaretha Foundation for Visually Impaired.
Source: http://www.medpagetoday.com/Ophthalmology/Gen...