[Disturbances of binocular vision in macular heterotopia].

BACKGROUND

Tractive translocation of the macula (secondary macular heterotopia) may result in disturbance of binocular vision. The report of a case shall discuss the sensorial problems of these patients.

HISTORY AND SIGNS

We report of a 40-years old male who had decreased visual acuity and loss of binocular vision for several years due to episodes of uveitis with intravitreous hemorrhage and cataract formation. After bilateral vitrectomy and cataract extraction a good visual acuity was restored in both eyes. Postoperatively, the patient monocularly complained about disturbed egocentric localization (tilting of the visual environment, "past-pointing") and metamorphopsia. Binocularly he was confused by doubled vision with tilted images. Both maculae showed a tractive translocation of 15 degrees downward. Measurements of binocular alignment with the tangent screen showed an excyclotropia of 8 degrees and an exotropia of 7 degrees in all directions of gaze. Haploscopic examination with fusion images demonstrated that sensorial fusion was not possible even with perfect ocular alignment due to disturbed relative retinal localization (obligate fixation disparity).

THERAPY AND OUTCOME

Initially, full time occlusion of the left eye was required. After improvement of symptoms occlusion therapy was slowly tapered. Within one year the patient had learned to suppress the image of his left eye and reported only minor residual visual disturbances even without occlusion of his left eye.

CONCLUSIONS

Secondary translocation of the macula monocularly results in a disturbance of egocentric localization and in metamorphopsia. Binocularly doubled vision with tilted images and a loss of sensorial fusion are seen. With monocular vision, perceptual adapting to the aberration in egocentric localisation is possible within weeks by reallocation of the retinal meridians in the central nervous system. Binocular improvement of symptoms is limited to the learning of suppression. Improvement of binocular symptoms by adaptation of retinal correspondence does not occur.