Correction of cyclovertical strabismus induced by limited macular translocation in a case of age-related macular degeneration

Diplopia and strabismus following ocular surgeries

Postoperative diplopia and strabismus may result from a variety of ocular surgical procedures. Common underlying mechanisms include sensory disturbance, scarring, direct extraocular muscle injury, myotoxicity from injections of local anesthesia or antibiotics, and malpositioning of extraocular muscles by implant materials. The most common patterns are vertical and horizontal motility disturbance. Treatment options include prisms, botulinum, occlusion, or surgery.

Use of rotational sutures for limited retinal translocation: a new technique for superior limited macular translocation

PURPOSE

To report a modified surgical technique for retinal translocation in eyes with subfoveal choroidal neovascularization.

DESIGN

Experimental animal study.

METHODS

Nine pigmented rabbits were used consecutively to apply this technique. Placement of inferotemporal scleral imbrication sutures was followed by vitrectomy with posterior hyaloid separation. Balanced saline solution (BSS) was injected subretinally with a 30G needle or with a 39G hydrodissection cannula and viscous fluid injector to detach one retinal quadrant. Under low intraocular pressure, the imbrication sutures were tied, the sclerotomy sites were closed, and intravitreal air tamponade was injected. Rotation sutures were passed and the eye globe was rotated approximately 90 degrees counterclockwise. The rotation sutures were removed after 24 hours. Retinal photographs were taken and fundus examination was performed on postoperative days 1, 2 and 7. The animals were sacrificed after 7 to 10 days for postmortem macroscopic examination.

RESULTS

The entire procedure was performed in nine eyes of nine rabbits. In eight eyes, translocation could be seen on the first postoperative day after removal of the rotation sutures. The average amount of translocation was 667 microm (range: 500-800 microm) in a nasal to inferonasal direction. Vitreous hemorrhage occurred at the end of surgery in one eye due to hypotony. Iatrogenic small retinal breaks occurred in 2 eyes but did not prevent completion of the procedure. There was only a temporary hyperemia of the eyelids and conjunctiva.

CONCLUSION

Limited retinal translocation using rotational sutures provided a predictable amount of translocation in the planned direction. This technique is expected to be useful for superior macular translocation in humans.

Transposition of the anterior superior oblique insertion as a treatment for excyclotorsion induced from limited macular translocation

PURPOSE

To evaluate the transposition of the anterior superior oblique insertion as a treatment for cyclovertical diplopia accompanied by an awareness of tilted image perceived with the affected eye induced from limited macular translocation (LMT).

DESIGN

Observational case series.

METHODS

Transposition of the anterior part of the superior oblique tendon combined with or without vertical muscle surgery on the affected eye was retrospectively studied in seven patients. Clinical outcome was assessed for binocular and monocular vision. A successful result was defined as restoration of single binocular vision (SBV) at distance and near examined with the Bagolini test with disappearance of a tilted image perceived in the affected eye.

RESULTS

Six of seven patients (86%) became unaware of tilted image, and three patients (43%) obtained successful results after the strabismus surgery. Of these three patients with successful results, one (33%) patient recognized metamorphopsia, whereas two (67%) of the three patients with unfavorable results reported metamorphopsia. Patients with successful results showed a visual acuity of 20/25 or better in the affected eye and a significantly smaller difference in visual acuity between the two eyes than those patients with unfavorable surgical results (0.133 logarithm of the minimal angle of resolution for SBV(+) vs 0.675 logarithm of the minimal angle of resolution for SBV(-); P =.0255).

CONCLUSIONS

The relatively low success for restoration of SBV indicates that strabismus surgery is recommended for patients whose difference in visual acuity between the two eyes is small and who have a high level visual acuity of the affected eye.

Diplopia after limited macular translocation surgery

PURPOSE

Full macular translocation surgery relocates the fovea away from choroidal neovascularization, inducing significant postoperative torsional diplopia. In "limited macular translocation," a saline-induced retinal detachment is followed by scleral imbrication with mattress sutures and spontaneous retinal reattachment. In this study, diplopia was characterized in patients treated with limited macular translocation.

METHODS

Two surgeons performed retinal translocation surgery on 250 patients over an 18-month time span. The extent and direction of the retinal translocation, and the amount and location of scleral imbrication, were recorded. All patients complaining of diplopia were referred for ocular motility evaluation and treatment.

RESULTS

Thirteen (5.2%) patients complained of occasional or constant diplopia. Imbricating sutures were placed supero-temporally in all cases. Inferior foveal translocation ranged from 200 to 2115 microm (median, 1750 microm). Visual acuity ranged from 20/40 to 20/400 in the operated eye. Prism-and-cover testing underestimated the strabismus when compared with subjective testing. In 3 patients, there was no shift on alternate-cover testing despite binocular diplopia. Excyclotorsion ranged from 0 degrees to 16 degrees. Diplopia resolved in 10 cases with prism; 3 required an occlusive filter for distortion or aniseikonia. One patient underwent successful strabismus surgery to eliminate dependence on prism glasses.

CONCLUSIONS

Limited macular translocation only rarely produces symptomatic diplopia. Suprisingly, traditional prism-and-cover testing does not reliably quantify the misalignment. This may result from the combination of a persistent macular scotoma and a repositioned fovea relative to the peripheral retina. Prism therapy is generally satisfactory in the absence of retinal distortion or aniseikonia.