Ocular motility disturbances after glaucoma drainage device implantation for paediatric glaucoma: a cross-sectional study

Aim To grade extraocular motility in the field of action of each extraocular muscle following superotemporal glaucoma drainage device (GDD) implantation in a paediatric population and to investigate which drainage device (Ahmed vs Baerveldt) yields less extraocular motility disturbance. Methods Cross-sectional study of children with a GDD implanted consecutively by a single surgeon who underwent ocular motility examination by two masked orthoptists. Ductions in the cardinal positions were graded. Ocular alignment, visual acuity, binocularity, stereopsis and intraocular pressure were also measured, and patient charts were reviewed. Results Thirty children each had one eye included. Twenty-one eyes had an Ahmed GDD and 9 had a Baerveldt GDD. Mean time between GDD insertion and ocular motility exam was 68 months in the Ahmed group and 19 months in the Baerveldt group. Exotropia was present in 46% and vertical heterotropia in 46% of children post-GDD insertion. Thirty-three percent of eyes had a moderate or severe limitation of elevation in abduction, 30% of elevation in adduction, 10% of abduction and 10% of adduction. There was a trend towards more eyes in the Ahmed group (62%) having at least a moderate limitation in ocular motility (-2 or worse; scale -1 to -4) compared with the Baerveldt group (22%). Conclusion Strabismus is common in children with GDDs. Our motility and alignment findings are consistent with either a mass effect of the device and bleb and/or scarring beneath the plate in the quadrant of the GDD causing dysmotility, most commonly limitation towards the GDD.