Transconjunctival orbital decompression in Graves' ophthalmopathy: lateral wall approach ab interno

Abstract

Aims: A modified surgical technique is described to perform a one, two, or three wall orbital decompression in patients with Graves' ophthalmopathy.

Methods: The lateral wall was approached ab interno through a "swinging eyelid" approach (lateral canthotomy and lower fornix incision) and an extended periosteum incision along the inferior and lateral orbital margin. In addition, the orbital floor and medial wall were removed when indicated. To minimise the incidence of iatrogenic diplopia, the lateral and medial walls were used as the first surfaces of decompression, leaving the "medial orbital strut" intact. During 1998, this technique was used in a consecutive series of 19 patients (35 orbits) with compressive optic neuropathy (six patients), severe exposure keratopathy (one patient), or disfiguring/congestive Graves' ophthalmopathy (12 patients).

Results: The preoperative Hertel value (35 eyes) was on average 25 mm (range 19-31 mm). The mean proptosis reduction at 2 months after surgery was 5.5 mm (range 3-7 mm). Of the total group of 19 patients, iatrogenic diplopia occurred in two (12.5%) of 16 patients who had no preoperative diplopia or only when tired. The three other patients with continuous preoperative diplopia showed no improvement of double vision after orbital decompression, even when the ocular motility (ductions) had improved. In the total group, there was no significant change of ductions in any direction at 2 months after surgery. All six patients with recent onset compressive optic neuropathy showed improvement of visual acuity after surgery. No visual deterioration related to surgery was observed in this study. A high satisfaction score (mean 8.2 on a scale of 1 to 10) was noted following the operation.

Conclusion: This versatile procedure is safe and efficacious, patient and cost friendly. Advantages are the low incidence of induced diplopia and periorbital hypaesthesia, the hidden and small incision, the minimal surgical trauma to the temporalis muscle, and fast patient recovery. The main disadvantage is the limited exposure of the posterior medial and lateral wall.

Figures

Figure 1

Anterior view of the right bony orbit. The four orbital walls can be selectively removed for orbital decompression. The following walls are identified: the medial wall (a), the orbital floor, divided by the infraorbital nerve into a medial part (b), and a lateral part (c), the anterolateral wall (d), the posterolateral wall (e), and the orbital roof (f). The bony junction between (a) and (b), the "orbital strut", is arrowed.

Figure 2

Frontal view showing the preoperative (A) and postoperative appearance after 2 months (B) of a 61 year old woman with burnt out Graves' ophthalmopathy. There was 6 mm reduction of proptosis after bilateral 2.5 wall orbital decompression at 2 months after surgery. (C) Left lateral view of the same patient depicted in (A) and (B), showing the preoperative appearance (C), and the postoperative appearance after 1 week (D) and after 2 months (E). Note the lateral extended canthotomy scar (on average 15 mm) parallel to the relaxed skin tension lines (D).

Figure 3

Preoperative axial orbital computed tomography (CT) scan, showing severely enlarged extraocular muscles ("apical crowding") in a case of compressive optic neuropathy (A). The postoperative scan (B) shows the effects of bilateral medial (open arrow) and lateral (closed arrow) wall removal at 2 months after surgery. The visual acuity recovered completely within a week.

Figure 4

Preoperative and postoperative (at 2 months) Hertel values in 19 patients (35 orbits) who underwent a transconjunctival orbital decompression.

Figure 5

Preoperative and postoperative diplopia in 19 patients who underwent transconjunctival orbital decompression.

Figure 6

Preoperative and postoperative ductions in 19 patients who underwent transconjunctival orbital decompression. There was no statistically significant change in preoperative and postoperative ductions in any direction (p>0.05).