# Normative data for accommodative facility and vergence facility in a sample of African school children aged 8–17 years

## TL;DR

This study provides normative data for accommodative and vergence facility in African children aged 8–17 years in Ghana, filling a gap in existing literature.

## Contribution

The study establishes first-time normative data for vergence facility and expands accommodative facility norms to younger children in an African population.

## Key findings

- Median monocular accommodative facility was 13 cpm with an interquartile range of 4 cpm.
- Vergence facility had a median of 14 cpm with a central tendency range of 10–18 cpm.
- Normative values are specific to Ghanaian children aged 8–17 and can guide clinical comparisons.

## Abstract

The existing literature on normative data for accommodative facility (AF) in African populations is limited to high school students. There is no normative data for vergence facility (VF) in African children, so there are no benchmarks for comparison in case analysis, diagnosis, and management. The study aimed to establish normative data for AF in children aged 8–12 years. Additionally, the study sought to determine normative data for VF in children aged 8–17 years in the Cape Coast metropolis, Ghana.

Normal children (510) were recruited through a comprehensive oculo-visual examination of 2,300 basic school-going children, aged 8–17 years. AF was measured with a ± 2D flipper lens for 1 min. VF was measured with a 3-base-in/12 base-out flipper prism for 1 min. Normative data were derived using the median with interquartile ranges (IQR) and considering the spread of data within the minimum and maximum ranges.

A median value of 13 cpm with IQR of 4 cpm was determined for monocular accommodative facility (MAF). The normative central tendency for MAF for school children 8–17 years ranges from 9 to 17 cpm; data were widely spread, with a minimum of 4 and a maximum of 20 cpm. A median value of 13 cpm with IQR of 3 cpm was determined for the binocular accommodative facility (BAF). The normative central tendency for BAF for school children aged 8–17 years ranged from 9 to 14 cpm; data were widely spread, with a minimum of 5 and a maximum of 20 cpm. A median value of 14 cpm with IQR of 4 cpm was determined for VF. The normative central tendency for VF for school children 8–17 years ranged from 10 to 18 cpm; data were widely spread, with a minimum of 6 and a maximum of 21 cpm.

The normative data apply only to similarly aged Ghanaian children and serve as standards for comparison to clinical data for MAF, BAF, and VF during case analysis.