Long-term effects of the crowding training and transfer to untrained tasks

The crowding training is an evidence-based intervention for 4-8 year old
children with a visual impairment who suffer from crowding and/or have a poorer
near visual acuity than distance visual acuity. The training reduces crowding
and improves near visual acuity: children show an average visual acuity
improvement of 1.7 lines on the crowded chart and an improvement of 1.3 lines
on the uncrowded chart. In addition, we found shorter visual search times after
training. It is unclear to which extent training effects are retained after
training.

The project has two goals: 1) to detemine how much of the training effects are
retained after 6 and 12 months, and 2) to determine whether the training
improves reading and/or fine motor skills. We expect that the results of this
project will be in line with earlier studies and expect that 80-90% of the
treatment effects will be retained after 6 to 12 months. We also expect that
children will be able to read smaller font sizes after training.

• Determine to which extent near visual acuity and crowding improvements are
retained at 6 and 12 months after training
• Determine transfer of training effects to untrained tasks, in this case
reading and fine motor performance.

Non-randomized pretest-posttest design.

The *crowding training* is an evidence-based intervention that has been
implemented at Bartiméus and Royal Dutch Visio (also see project number
2010/037). The *crowding training* is a behavioural treatment in which children
are instructed to draw a line across near-threshold, closely spaced, inversed
Es in a booklet. By training with Es that at presented in a crowded setting,
selective visual attention, eye-hand coordination and visual acuity are
trained. The training will be given during 6 weeks, with 2 training sessions
per week (12 × 0.5h training sessions in total).

The burden on parents and children will be minimized by training the children
at school and collecting the pre- and posttest data directly before and after
training at school. The post-tests at 6 and 12 months will be conducted at the
research institute with the same standardized tests that are used for the
pre-test and first post-test. Pre- and post-tests can be collected within 30-40
minutes. Training sessions will occur at school. Benefits for the participants
are that they can use an evidence-based training to improve near visual acuity
and reduce crowding. Near visual acuity is an important outcome measure,
especially in subjects with a visual impairment because they are more dependent
on this function than individuals with normal vision. There are no risks
associated with this child-friendly validated behavioural treatment.