Observations in Sensory Heterotropia

Abstract

Sensory heterotropia is defined as a secondary deviation following loss or severe reduction in visual function in one eye. We have analyzed the records of 12 1 patients with sensory heterotropias with the purpose of correlating the direction deviation of (eso- or exotropia) with age of onset of visual loss. Esotropia and exotropia were encountered with almost equal frequency when the onset of visual impairment occurred at birth or between birth and 5 years of age and exotropia predominated in older children and adults. We also found a strikingly high incidence of dysfunction of the oblique muscles in patients with sensory eso- and exodeviations. The inferior oblique muscle was the most freq uently involved muscle. Sensory heterotropia is defined as a deviation of one eye following loss or severe impairment of visual acuity. Due to a sensory obstacle to fusion, the fusion reflex innervation becomes suspended and the visually impaired eye changes its position relative to that of the fixating eye and becomes esotropie or exotropic. While most authors agree that the direction of the deviation (esotropia or exotropia) depends on the age at which the visual impairment occurred, there is little agreement on the type of strabismus in the various age groups. For instance, Chavasse1 stated that eyes born blind or having lost vision shortly after birth diverge. Hamburger,J on the other hand, writes that most eyes with congenital unilateral blindness or severe visual impairment in early childhood converge. There is similar disagreement as to the direction of strabismus when the onset of visual impairment is during childhood or adolescence. In view of this discrepancy, and as our preliminary clinical impressions were not in accord with either of the two extreme views stated above,1 we analyzed the records of patients with sensory tropia with the purpose of describing the clinical characteristics of this entity.

A study of clinical, etiological demographic profile of patients with concomitant esotropia between ages 0-10 years

“…In the present study 46.15% of patients presented with a deviation between 25-49 PD While 53.84% of patients presented with deviation >50PD. In contrast to this in the study done by Costenbader et al 6 24.65% of patients presented a deviation between 0-24 PD, 30.94% of patients presented with a range of 25-49 PD, and 44.41% of patients presented with a deviation greater than 50 PD.…”

Sensory exotropia versus sensory esotropia: A comparative clinical features study

“… 10 , 16 , 27 Unfortunately, we did not have the data on age at the time of visual impairment; however, the results of other studies with this data confirm that age at the onset of visual impairment plays an important role in determining the direction of the strabismus. Studies have shown that when sensory deviation occurs under the age of 5 years old, there is either an equal possibility 5 or less difference 15 for developing sensory esotropia or exotropia; however, when sensory strabismus occurs at an older age, there is a more possibility of developing sensory exotropia than esotropia. 9 , 15 , 16 …”

“… 6 , 10 , 11 , 12 Several factors can determine the direction of sensory strabismus, namely, age at the time of visual impairment, refractive error in the normal eye, degree of visual acuity, and anatomical factors 3 , 4 , 13 , 14 ; however, there is still no consensus. Sidikaro and von Noorden 5 and Min et al 8 found that esotropia is relatively dominant when visual impairment occurs immediately after birth or before the age of 5 years. Havertape et al 3 reported that esotropia was dominant for congenital visual loss occurring within six months of age, and sensory exotropia for acquired visual loss over 22 months of age is the predominant form of sensory strabismus.…”

“…Sensory strabismus refers to a secondary ocular deviation due to the disruption of sensory fusion that occurs mainly after loss or severe reduction in visual acuity in one or both eyes. 3 , 4 , 5 Numerous risk factors can induce sensory strabismus. From the clinical perspective, every persistent unilateral or bilateral vision loss at any age can contribute to developing secondary or sensory strabismus.…”

Unilateral surgery for pediatric sensory exotropia: clinical characteristics and surgical results

“…As regard the etiology of sensory strabismus, Kim and coauthors [ 5 ] found that cataract was the most common cause (71.7%) of all patients, followed by optic nerve disorder, retinal detachment, glaucoma and lens subluxation. Sidikaro and von Noorden [ 18 ] reported that anisometropic amblyopia was the main cause of sensory strabismus, and that cataract and corneal opacities were less common. However, Havertape et al [ 20 ] found that cataracts were the most frequent cause, followed by optic nerve disorders and anisometropic amblyopia.…”