Clinical Manifestations and Treatment Outcomes in Dissociated Strabismus Complex (DSC) Patients

Objective: To demonstrate clinical manifestations and treatment outcomes in dissociated strabismus complex patients. Methods: Charts of patients who attended the Muscle Clinic at Siriraj Hospital from July 1998 to June 2003 were reviewed. Information regarding the patient’s age, sex, eye deviation, visual acuity, binocular function, head posture, latent nystagmus, degree of dissociated vertical deviation (DVD), dissociated horizontal deviation (DHD), dissociated torsional deviation (DTD), inferior oblique overaction (IOOA) and the treatments were obtained. Results: Seventy-three subjects from 1,335 strabismic patients were included in the study (5.5% of all strabismic patients attended the Muscle Clinic during the study time). The mean age of DSC patients was 8 years old. Among all DSC patients, 65.8% had esodeviation; 23.2% had exodeviation; and, 11% had isolated DSC. Latent nystagmus was found in 11% of the patients. Abnormal head posture was found in 16.4% of the patients. About fifteen percent of DSC patients had binocular function. All DSC patients had DVD but only 5 patients had DHD; no DTD was found. The treatment of DHD was correction of the horizontal deviation that coexisted with vertical deviation. As for DVD, there were many surgical procedures for correction such as superior rectus muscle (SR) recession, inferior oblique muscle (IO) recession, inferior oblique muscle anteriorization and inferior rectus muscle (IR) resection. Both unilateral and bilateral surgeries were performed. Regardless of the procedures, the total success rate was 78.4% (the residual of hyperdeviation was 10 prism diopters (PD) or less). The group of patients, who had surgical correction in only one eye, had a significant deviation in the non-operated eye after the surgical treatment. Conclusion: DSC was composed of DVD, DHD, DTD and latent nystagmus. DVD was the predominant manifestation in most cases of DSC. DSC was usually bilateral and was seen in subnormal binocular function patients. Esotropia was the most common deviation associated with DSC patients. Many surgical procedures were used to correct DVD such as bilateral large SR recession or IO anteriorization. In unilateral surgery, the manifestation of the deviation in the non-operated eye was usually be found. Bilateral surgery was suggested but may be performed in asymmetrical degree. In this study, the overall success rate was 78.4%.