August 12, 2015
1 min read

Axial elongation correlated with age, summed corneal power change

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Researchers identified relationships between axial length and summed corneal power change and age in myopic children undergoing orthokeratology contact lens wear, according to a study recently published in Investigative Ophthalmology & Visual Science.

Zhong and colleagues conducted a longitudinal, prospective study of 64 children with myopia between the ages of 7 years and 12 years. The children were fitted with spherical four-zone ortho-K lenses (Hiline, Marco Vision).

Researchers measured axial length at baseline and then every 6 months throughout the duration of the 2-year study. They also evaluated corneal apical refractive power and the mean power of concentric rings at 0.1 mm intervals between 0.5 mm and 7.2 mm diameters using the Pentacam HR (Oculus) at baseline and after 3 months of ortho-K lens use.

The researchers utilized a stepwise multiple linear regression model to test axial length growth with baseline spherical equivalent refractive error (SERE), summed corneal power change (SCPC) and age. They defined SCPC as "the sum of relative corneal power change within the area of 7.2 mm diameter."

Results showed that children demonstrated a mean axial growth of 0.37 ± 0.27 mm. After 3 months of ortho-K lens wear, mean SCPC was 10.84 ± 5.28 D mm, and corneal apical refractive power and SERE had decreased from 43.47 ± 1.03 D and -2.88 ± 0.96 D to 40.61 ± 1.23 D and -0.20 ± 0.85 D, respectively. Researchers reported significant correlations between axial elongation and SCPC and baseline age.

"Axial elongation in children undergoing ortho-K therapy is negatively correlated with the age of the wearer and summed corneal power change from the central to the mid-peripheral cornea," the authors concluded. "We speculate that axial elongation is influenced by the extent to which the retinal defocus profile is altered with ortho-K lens wear." – by Chelsea Frajerman Pardes

Disclosures: The authors report no relevant financial disclosures.