Occurrence of Dissociated Vertical Deviation in Horizontal Concomitant Heterotropia: A Hospital-Based Study

Abstract

BACKGROUNDDissociated Vertical Deviation (DVD) is a poorly understood supranuclear strabismic disorder in which there is slow upward and sometimes temporal movement of one eye with cortical suppression of vision in that eye when it is occluded. In DVD, one eye get dissociated from the fellow eye, so they don't follow Hering's and Sherrington's laws of innervation. DVD is also a marker of disruption of normal binocular function, which causes unbalanced input to vestibular system resulting in latent nystagmus with a cyclovertical component. To overcome this cyclovertical component, vertical vergence is invoked for which vision is aided in the fixing eye, but unfortunately it also produces DVD of the fellow eye. DVD is most commonly associated with infantile esotropia. AIM To determine whether age of onset of strabismus is related to the development of dissociated vertical deviation in patients with horizontal concomitant heterotropia (HCH).To find out the occurrence of dissociated vertical deviation among patients with horizontal concomitant heterotropia and also to calculate how many of them is suffering from refractive error.  DESIGN This is a cross-sectional, observational hospital-based study. MATERIALS AND METHODThis study was done in 100 children presenting with horizontal concomitant heterotropia randomly chosen in the age group 5 yrs.-19 yrs. attending outpatient department and squint clinic of Regional Institute of Ophthalmology, Kolkata. After taking proper history regarding time of onset of strabismus, age of onset of DVD, they underwent a full ophthalmic examination including visual acuity assessment, cycloplegic refraction, assessment and measurement of squint and DVD, and stereopsis. RESULTMean age of horizontal concomitant heterotropes was 9.28 yrs. ± 3.94 yrs. of which 48% were male and 52% were female. Among horizontal concomitant heterotropes 24% were exotropes and 76% esotropes. The mean age of onset of strabismus in horizontal concomitant heterotropes leading to the development of DVD was 7.93 yrs. ± 9.95 yrs. Dissociated vertical deviation was present in 14% of horizontal concomitant heterotropia of which 78.57% were male and 21.43% were female. We found that 78.58% of DVD patients were having some type of refractive error. CONCLUSIONThis clinical study is a small endeavour on our part to suggest an earlier age of onset of strabismus is associated with higher chances of development of dissociated vertical deviation and we have also noticed a higher incidence of DVD in infantile esotropia.