Silicone Band in the Surgical Treatment of Manifest Exotropia

doi:10.4236/ojoph.2013.31001

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Open Journal of Ophthalmology, 2013, 3, 1-3

http://dx.doi.org/10.4236/ojoph.2013.31001 Published Online February 2013 (http://www.scirp.org/journal/ojoph)

Silicone Band in the Surgical Treatment of Manifest

Exotropia

Lelio Sabetti, Antonio Berarducci, Domenico Di Lodovico

Eye Clinic, San Salvatore Hospital, University of L’Aquila, L’Aquila, Italy.

Email: [email protected]

Received June 14th, 2012; revised August 15th, 2012; accepted August 23rd, 2012

ABSTRACT

Purpose: A silicone band was sutured anteriorly to the edge of the lateral rectus muscle neotendon during recession

surgery in order to reduce and delay the reoccurrence after exotropia surgery. Methods: Collected data of 12 patients (8

males and 4 females), aged 7 - 54 years with diagnosis of constant manifest exotropia and mean angle deviation in pri-

mary position of 15,04˚ (sd 1,18) for near and of 13,23˚ (sd 0,71) for distance. All patients underwent surgical treatment

consisting of lateral rectus recession and silicone band apposition in correspondence to the anterior edge of the lateral

rectus muscle neotendon. Results: A substantial reduction of the mean angle deviation was observed in all patients after

surgery. No adverse band-related effects were detected. Conclusion: The silicone band in the surgical treatment of

manifest exotropia could be a valuable aid in delaying the relapse thanks to its physical and structural features and to its

biocompatibility.

Keywords: Silicone Band; Exotropia; Recession; Lateral Rectus Neotendon

1. Introduction

Surgery represents the gold standard treatment in eyes

exodeviations. Several processes are implicated in the

exodeviation genesis but neurological lesions [1] are the

most frequent. Surgical technique is planned according to

deviation grade, sensory status and age of the patients

[2,3] and it includes bilateral lateral rectus recession and/

or unilateral medial rectus resection (which is strictly re-

lated with the primary deviation degree [4-6]). The use of

adjustable sutures might represent an effective aid in the

surgical management [7] as well as dominant or non-do-

minant eye surgery might produce different functional

outcomes [8,9].

Early post surgery complication is represented by sur-

gical hypocorrection [10] but the most important long

term complication is the long term deviation relapse [11].

Different factors are involved in the genesis of the re-

occurrence. Besides the clinical features of the primary

deviation and the abnormal wide neotendon regrowth in

correspondence of the new insertion (microscopic evi-

dence of Schwann cell degeneration both with an in-

crease of the neurofilaments density, axonal vacuoles and

hydric swelling [12,13]), level variation of some proteins

[14] such as fibronectin, proteoglycans, aggrecans and

laminin [15] seem to play a basic role in the resected mus-

cles.

The relapse management consist in surgery [16] in-

volving lateral rectus or medial rectus (unless previously

treated) [17,18].

According to several studies, relapse occurs in about

33% of cases and it might happen even following redo

surgery (although with a lower probability compared

with the first surgery [6,19,20]).

Most of the extreme eyes deviation (30˚ - 45˚ or 60Δ -

90Δ Δ= prismatic diopter) evolve to secondary strabis-

mus forms due to recession/resection surgical protocol,

extreme anisometropia or surgical trauma [21].

Some surgeons suggested a protocol consisting of a

free mucosal transplantation [21] to treat secondary de-

viations (over 45˚ equivalent to 90Δ).

However, exodeviation surgical correction is still rep-

resenting a difficult challenge due to the several and dif-

ferent clinical features which make difficult the surgical

approach and apparently aleatory outcomes.

2. Materials and Methods

The goal of our study was to estimate the effect of a sili-

cone band sutured anteriorly to the lateral rectus neoten-

don insertion during recession surgery in order to reduce

and delay the relapse in the surgical treatment of exot-

ropia.

The study was carried out at the S. Salvatore Hospital

of L’Aquila, in the Ophthalmology Unit, from June 2006

to December 2009. Data of 12 patients (8 males and 4

Silicone Band in the Surgical Treatment of Manifest Exotropia

females) aged between 7 - 54 years with well-known dia-

gnosis of manifest constant exotropia were collected; ma-

ximum follow-up at 42 months.

The pre surgical evaluation consisted in anamnesis (in

order to evaluate present complaint and previous ocular

history); complete ophthalmological assessment; cyclo-

plegic retinoscopy (using tropicamide 1% and cyclopean-

tolate 1%); best corrected and uncorrected visual acuity

check; orthoptic examination (cover-uncover test at both

near and distance fixation; ocular motility examination;

Worth Lights Test and microWorth test; Titmus Stereo

Test and Lang Stereo Test).

The presurgical orthoptic assessment revealed exo-

tropia in all patients; the mean deviation angle at near

was 15.4˚ (sd 1.18) and at distance was 13.23˚ (sd 0.71).

The Titmus Test showed absent stereopsis in 50% of

patients (6/12) and a complete perception of circles, with

average retinal image disparity of 100 arcs in the remain-

ing 50% of cases.

Ten over twelve patients (84%) suppressed one eye

with the Worth Lights Test and the remaining 16% of pa-

tients (2 over 12) was able to fuse with a proper prismatic

correction.

All the procedures were performed by the same ex-

perienced surgeon and consisted in 360˚ limbal conjunct-

tival peritomy, medial rectus muscles isolation, lateral

rectus recession and silicone band apposition (Novolene

5.0 suture) just anteriorly to the neotendon insertion,

layer suture.

3. Results

Patients underwent follow up assessment every 6 month;

final assessment performed at 42 showed the following

results: 8 over 12 patients (66%) presented exotropy

(mean angle deviation of 3.43˚ sd 0.87) at near fixation;

in the remaining 34% of cases (4 over 12) exoforia was

detected (mean angle deviation: 4˚ sd 0.73). Orthophoria

for distance was obtained in 25% of cases (3 patients

over 12) and exoforia was still present in 3 over 12 pa-

tients (25%) (mean angle deviation of 3.42˚ sd 0.58). In 6

over 12 patients residual small angle exotropia (<1.5˚ of

deviation). With regards of the sensory evaluation, in

50% of cases (6 over 12 cases) a modified stereoscopic

vision consisnting in perception of the fly, animals and

circles was detected, but with a retinal image disparity of

80 arcs. Sensory status check demonstrated suppression

in one eye during the test in 10 over 12 cases (84%),

while in the remaining 16% of patients (2/12) fusion was

obtained using an appropriate prismatic correction.

4. Discussion

According to several studies, resection/recession surgery

produces good outcomes in about 60% - 80% of patients

[22] and an early hypercorrection (4Δ - 6Δ) [23] seems to

represent the only positive predictive factor in the long

term success.

Some surgeons proposed to measure intraoperatively

the deviated lateral rectus neotendon width in order to

estimate the possible functional outcome [24]. A retro-

spective study involving 350 patients surgically treated

for exotropia demonstrated that a good long term out-

come (outbreak relapse mean time = 48 months [25] and

64 months [11]) could be achieved performing a postsur-

gical hypercorrection higher than 10Δ of isotropia [25].

Hypercorrections higher than 17Δ are often related

with consequent secondary isotropia; in these cases, the

greatest risk factor [26] is mainly represented by lateral

incomitance. A recent study in 2005 showed that hyper-

corrections higher than 20Δ need a subsequent surgical

treatment due to a consequent isotropia in 5%, 9% of the

patients [27].

Recently, a 20-year retrospective study involving pa-

tients who underwent exotropia surgery before age 10

suggested that stable eye alignment obtained in 11 year

old patients tends to be the same until age 30 [28].

The analysis of the results obtained in our study de-

monstrated a substantial reduction of the mean angle de-

viation at 42 months after surgery associated with a sig-

nificant improvement in terms of motor fusion and no

presence of flogistic reactions related to silicone band.

Stereoscopic sense remained unmodified and the sensory

status examination continued to show suppression in one

eye. Finally, ocular motility examination didn’t suggest

any duction disability.

In conclusion, the silicone band in the surgical treat-

ment of manifest exotropia could be a valuable aid in de-

laying the relapse thanks to its physical and structural

features and to its biocompatibility.

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