Scleral Graft and Muscle Transposition in the Treatment of Scleromalacia and Hypertropia Following Retinal Detachment Surgery

Introduction

Adhesion syndromes, sensorial strabismus, and motility alterations secondary to scleral implants and torn, slipped or lost muscles are possible causes of strabismus following retinal detachment (RD) surgery.¹

Scleromalacia may have an inflammatory origin frequently related with autoimmune diseases. Also, it may be produced by an accidental or surgical ocular trauma or by infection.^2,3

We report a case of scleromalacia and hypertropia consecutive to rupture of the inferior rectus muscle (IRM) as a consequence of RD surgery, treated with a cadaveric scleral graft (CSG) and anterior transposition of the ipsilateral inferior oblique muscle (ATIIO) in one single surgical procedure.

Case Report

A 41-year-old man referred vertical diplopia of 5-month of evolution that started immediatly after an RD surgery of his left eye. An encircling scleral buckle had been removed 45 days after the surgical procedure because of a severe inflammatory process. At the initial visit, best-corrected visual acuity was 10/10 in the right eye and 7/10 in the left eye. Motility evaluation revealed left hypertropia that increased in infralevoversion (Fig. 1, Table 1). The inferior temporal quadrant of the left eye showed a wide area of scleromalacia extending from 5 mm posteriorly to the limbus up to the retro-equatorial area, and circumferentially from the third to the seventh meridian (Fig. 2A).

Figure 1. Preoperative Diagnostic Gaze Positions Demonstrating Left Hypertropia, Which Increased in Infraversions.

Table 1: Preoperative Measurements (Prism Diopters) in the 9 Different Diagnostic Gaze Positions, Showing Marked Left Hypertropia that Increased Significantly in Infra-Levoversions

Figure 2. (A) Left Eye of the Patient Showing Extensive Area of Scleromalacia at the Inferior and Temporal Quadrants. (B) A Scleral Graft Sutured over the Scleral Defect, and Inferior Oblique Muscle Insertion Transposed at the Level of the Insertion of the Inferior Rectus Muscle. (C) Scleral Graft Evolution After 22 Months of Follow-Up.

After careful delamination of the adherent conjuctiva overlying the scleromalacia area, a patch of CSG was prepared according to the defect’s size, and was sutured in place with direct nylon 9-0 stiches (Fig. 2B). As only a short and completely retracted distal stump of the IRM could be found far beyond the equator, correction of strabismus was performed by means of an ATIIO. The inferior oblique muscle (IOM) was desinserted from its scleral insertion and reinserted over the CSG in the medial line 6 mm from the sclerocorneal limbus and at the site of the original insertion of the IRM. Floating 5-0 threaded polyglycolic acid stiches were used, whose free anterior endings were fixed juxtalimbarly in healthy sclera (Fig. 2B). The conjunctiva was slided and repositioned over de CSG and sutured with direct 8-0 threaded polyglycolic acid stiches.

After 22 months of follow-up the CSG was in place and nicely covered by a healthy conjunctiva (Fig. 2C). Orthotropia was observed in all but in the extreme inferior gaze positions and a wide field of coordinated movements of the eyes was recovered (Fig. 3, Table 2).

Figure 3. Postoperative Gaze Positions Where Orthotropia Is Observed, with the Exception of the Extreme Inferior Gaze Positions.

Table 2: Preoperative Measurements (Prism Diopters) in the 9 Different Diagnostic Gaze Positions, Showing only Discrete Left Hypertropia in Infraversions

Discussion

Strabismus as the consequence of a torn or sectioned extraocular muscle may result as a complication of trauma or in RD surgery, strabismus surgery or endoscopic paranasal sinuses surgery.^1,4–7

When one of the extremes of a torned or slipped muscle is not found or the lesion is too posterior, muscular transposition is indicated to restore muscle function and ocular alignment.

Previous reports have shown the efficacy of ATIIO in cases of vertical strabismus as a consequence of a loss or lesion of the IRM during extraocular surgery.^1,4–7 Alternatively, horizontal recti muscle transposition may be used. However, three muscles of the same eye of this patient would be involved, increasing the risk of anterior segment ischemia. ATTIO is a recession procedure that produces a weakening effect and a relative restriction to up gaze (anti-elevator function), for it may be useful in the treatment of IOM hyperfunction, dissociated vertical deviation and superior oblique paresis.^1,4–8 However, this procedure should not usually be used monocularly because of the possibility of producing an ipsilateral deficit of elevation, hypotropia in primary position and torsional diplopia. It may be indicated unilaterally in selected cases of vertical strabismus with poor unilateral vision or in post-traumatic or surgical loss of the IRM. With the original technique of IOM anteroposition the muscle is anchored on the sclera temporally to the IRM insertion,⁸ increasing the likelihood of restricting elevation due to the antero-posterior band effect of its neurofibrovascular bundle.⁹ In the technique used in our patient, the IOM was reinserted medially, possibly producing a more debilitating and less restrictive effect. After ATIIO, our patient did not present clinically evident restriction to elevation and showed only occasional discrete diplopia in extreme infraversions.

Scleritis may occur following different types of ocular surgery such as cataract, trabeculectomy, strabismus and pterigion.^10,11 It may be observed more frequently in patients with connective tissue diseases.¹⁰ Few reports address with scleromalacia following RD surgery.^2,12 Chechelnitsky, Mannis and Chu reported a case after RD surgery that included vitrectomy, endolaser and intraocular injection of 20% perfluoropropane gas. The patient presented a history of congenital cataract removed shortly after birth. The authors could not find a relationship between RD repair and cataract extraction and the development of scleromalacia.² Mauriello and Pokorny reported another case of scleral thinning developed after multiple RD surgeries without describing the procedures performed and without discussing its possible cause.¹² In our case, the history of severe postsurgical inflammation that obliged to the ablation of an encircling scleral buckle may orient the possible cause towards a scleritis.

When the sclera becomes extremely thinned with the risk of exposition of the underlying choroid, the scleral defect must be repaired to restore the integrity and resistance of the eye wall. For this purpose, dermal, duramater, amniotic membrane, cartilage, fascia lata, sclera or sclerocornea grafts have been used.^2,3,11,12 In our case, CSG gave good tectonic support and cosmetic appearance, with no evidence of rejection during follow-up. As the CSG is an avascular tissue, after its suture in place it must be covered thoroughly by healthy conjunctiva or an amniotic membrane graft to protect it and promote its survival.¹¹

To our knowledge, no previous report has been made concerning the description and repair in one surgical time of strabismus with a ruptured IRM and associated with scleromalacia following RD surgery.

In this case it was demonstrated the feasibility and good result after repairing scleromalacia with an homologous CSG and hipertropia with ATIIO at the level of the IRM insertion with floating sutures in one surgical intervention. The external eye wall repair allowed a suitable placement of a new scleral insertion for the IOM. No signs of anterior segment ischemia were observed during follow-up and the patient recovered a wide field of coordinated eye movements.