IOP, myopic progression and axial length in a COMET subgroup

Relationships between intraocular pressure (IOP) and baseline characteristics are explored in a subgroup of children participating in the Correction of Myopia Evaluation Trial. The 5-year follow-up also provides information on the relationship between IOP, myopic progression, and change in axial length.

Right eye IOP, cycloplegic autorefraction, and axial length were measured at baseline and annually in 104/118 children at one of the Correction of Myopia Evaluation Trial centers.

At baseline, IOP for the cohort was 15.92 +/- 4.16 mm Hg. IOP decreased (0.125 mm Hg/year) over the follow-up (p = 0.05). IOP of Blacks (n = 17; 19.88 +/- 4.24 mm Hg) was higher than Hispanics (n = 50; 15.77 +/- 2.44 mm Hg, p = 0.006), Whites (n = 25; 14.51 +/- 1.75 mm Hg, p = 0.0001) and all non-Blacks combined (n = 87; 15.38 +/- 2.26 mm Hg, p = 0.0006). IOP averaged over the six visits did not differ by gender (mean difference = 0.66 mm Hg). There was no significant association between baseline IOP and baseline myopia or myopic progression, and no significant relationship between IOP the year prior to myopic progression measured over the following year. The same results were found for IOP and axial length.

Small but significant ethnic differences were noted in the IOP of myopic children, with Blacks having higher values. IOP was not associated with gender, baseline refractive error, baseline axial length, myopic progression, or change in axial length over the 5-year observation period.