The relationship between axial length, age and intraocular pressure in children with primary congenital glaucoma.

Whilst axial length (AxL) from ultrasound examination is a useful clinical parameter for monitoring progression in younger children with glaucoma, distinguishing AxL changes due to raised intraocular pressure (IOP) from age is often challenging. Existing normograms have included a limited number of children with glaucoma. The aim of this study was to evaluate the relationship between AxL with age and IOP in children with primary congenital glaucoma (PCG) and develop a model for expected AxL increase with age. All children (n = 208; 397 eyes) with PCG who attended our tertiary eye care facility from June 2014 and July 2018 and had AxL and IOP measurements were included. The relationship of AxL with age and IOP was studied by applying a LOWESS fit and then mixed effects models. In the final model, age was the most significant factor influencing the growth of AxL (coefficient age 3.14[95% CI 2.91-3.35, p < 0.001], coefficient age2 - 0.53[95% CI, - 0.59 to - 0.47, p < 0.001]), and this association was influenced by the interaction of IOP with sex (p = 0.098 for girls relative to boys), the number of antiglaucoma medications (AGM [p < 0.001 for ≥ 3 AGM]) and glaucoma surgery (p = 0.015). This model enabled us to derive predicted values for clinical use in children with PCG to predict those with progressive glaucoma.