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Clinical risk factors for the development of
consecutive exotropia: a
comparative clinical study
Hande Taylan Sekeroglu1, Kadriye
Erkan Turan1, Jale Karakaya2, Emin Cumhur Sener1, Ali Sefik
Sanac1
1Department of Ophthalmology, Hacettepe University
Faculty of Medicine, Ankara 06100, Turkey
2Department
of Biostatistics, Hacettepe University Faculty of Medicine, Ankara 06100, Turkey
Correspondence
to: Hande
Taylan Sekeroglu. Department of
Ophthalmology, Hacettepe University Faculty of Medicine, Ankara 06100, Turkey. h_taylan@yahoo.com
Received: 2015-01-04
Accepted: 2015-04-24
Abstract
AIM: To compare a group of patients with consecutive
exotropia with patients who had ≤10
prism diopters (PD) esotropia or no deviation postoperatively in terms of
probable clinical risk factors for the development of consecutive exotropia.
METHODS: The study recruited fourteen patients who developed
consecutive exodeviation during follow-up period after the correction of
esotropia who were categorized as group 1 and thirty-one patients who had still
≤10 PD esotropia or no deviation at the final
visit that were considered as group 2. Clinical risk factors leading the
development of consecutive deviation were analyzed as the main outcome
measures.
RESULTS: The mean age of patients was 4.57±3.11y in group 1 and
5.10±3.52y in group 2 (P=0.634). There was no significant difference
of preoperative near and distant deviations among two groups (P=0.835, 0.928 respectively). The mean amount of medial rectus recession and
lateral rectus resection was similar in both groups (P=0.412, 0.648 respectively). Convergence insufficiency
and neurological diseases were more frequent in group 1 (P=0.007, 0.045). Accompanying neurological disease was found to be
as a significant factor increasing the risk of the development of consecutive
exotropia significantly [odds ratios (OR): 5.75 (1.04-31.93)].
CONCLUSION: Accompanying neurological disease appears to be a significant clinical risk
factor for the development of consecutive exodeviation during postoperative
follow-up after the correction of esotropia. However, larger studies are needed
in order to interpret the results to the clinical practice and to ascertain
other concurrent risk factors.
KEYWORDS: consecutive exotropia; esotropia; medial rectus
recession; neurological disorder; lateral rectus resection
DOI:10.18240/ijo.2016.06.17
Citation: Taylan Sekeroglu H, Erkan Turan K, Karakaya J,
Sener EC, Sanac AS. Clinical risk factors for the development of consecutive exotropia: a
comparative clinical study. Int J
Ophthalmol 2016;9(6):886-889
INTRODUCTION
Consecutive
exotropia is an exodeviation that mainly occurs after surgical treatment of
esodeviations. The prevalence has been reported to be between 4% and 27%[1-5]. Consecutive deviations
are generally considered as complications of strabismus surgery after which
orthophoria is targeted even tough
initial slight overcorrections may be desirable and even recommended in some
selected conditions such as intermittent exotropia[6-7]. Surgery is preferred in case of long lasting and treatment resistant
consecutive exotropia whereas botulinum toxin injection, prismatic glasses,
alternating occlusion, full myopic correction or orthoptic exercises are among
the nonsurgical methods used to overcome the disabling outcome induced by
consecutive deviations when temporary[8-10]. When the condition seems to be resistant or permanent, the
surgical management comprise the reversal of initial surgery and/or
intervention for the fellow eye regarding the amount of deviation.
Consecutive
exotropia is an undesirable and sometimes frustrating outcome of esotropia
surgery. Thus, this study was undertaken with the purpose of identifying the
risk factors for the development of consecutive exotropia by comparing a group
of patients who ended up with consecutive exotropia during follow-up with
another group of patients who had no deviation or still had ≤10 prism diopters (PD) esotropia at the last
visit eventhough both of them had the similar amount of preoperative esotropia
and surgery.
SUBJECTS AND
METHODS
A total of
45 patients who underwent surgery for the correction of esotropia were enrolled in this
retrospective study. The study was conducted in full accordance with the Tenets
of Helsinki and informed consent was obtained from all patients. The study was
carried out upon approval of the Institutional Review Board.
The patients
who had exotropia at near or at distance postoperatively were categorized as
group 1 whereas those who had ≤10
PD esotropia or no manifest deviation at the final visit were classified as
group 2. Two groups were mainly matched in terms of age at surgery,
preoperative near and distance deviation and amount and type of surgery.
Patients
having previous ocular surgery except from the mentioned esotropia surgery,
having incomitant or dissociated vertical deviation were all excluded.
The data
from the medical files of patients were collected in respect with demographic
characteristics, associated systemic diseases, preoperative and postoperative
deviations, type and amount of strabismus surgery, refractive status,
anisometropia, amblyopia and postoperative convergence ability.
All patients
underwent a complete ophthalmological examination and an orthoptic evaluation.
The prism and alternate cover tests were performed in order to assess and
quantify the deviation at near and distance when possible. All surgeries were
performed under general anesthesia and in theatre. Postoperative orthoptic
evaluation was based on the visit when the afore mentioned consecutive deviation was observed
for the first time in group 1, and the latest visit when the patient had still ≤10 PD esotropia or no deviation in group 2.
The further management of consecutive deviations was beyond the purpose of the
study.
Amblyopia
was defined as an interocular visual acuity difference more than 2 lines.
Anisometropia was defined as a the difference in refractive error of
0.75 diopter or greater.
As the main
outcome measure, risk factors contributing to the development of consecutive
exotropia were analyzed.
Statistical Analysis The data was evaluated in collaboration with the
Department of Biostatistics. Data analysis was performed by SPSS 15.0 (Statistical
Package for Social Sciences, SPSS Inc. Chicago, IL, USA) software package.
Numerical variables were evaluated for normality of data distribution by using
the Kolmogorov-Smirnov test. Descriptive statistics
were expressed as mean±standard deviation (SD) or median (min-max) according to
the assumption of normal distribution.
In case of normal
distribution of data, independent samples t-test was performed to compare
the means of two groups. Mann-Whitney U test was used for non-parametric
data. Before and after measurements was compared using paired sample t-test. Yates’ Chi-square test or Fisher-exact tests were used to compare difference between groups
for categorical variables. Binary
logistic regression was used to evaluate which independent variables (postoperative convergence, systemic
diseases, myopia) were statistically significant predictors of the binary dependent variable (groups). Using the
logistic models, odds ratios (OR) and their respective 95% confidence intervals
(CIs) were calculated. A P<0.05 was accepted as statistically significant.
RESULTS
A total of
45 patients (21 females, 24 males) were enrolled in the study. Group 1
consisted of 14 (5 females, 9
males) patients whereas group 2 included 31 (16
females, 15 males) patients.
The mean age
of patients in group 1 was 4.57±3.11y and 5.10±3.52y in group 2 (P=0.634).
The operation was performed as bilateral medial rectus (MR) recession in 10
patients (71.4%) in group 1 and in 24 patients (77.4%) in group 2. The
recession-resection procedure was performed in 4 (28.6%) patients in group 1
and in 7 (22.6%) patients in group 2. There was no significant difference among
both groups in terms of the type of strabismus operation (P=
0.717).
The mean MR
recession in bilateral MR recession procedure was 5.35±0.97 (3.5-6.5) mm in
group 1 whereas it was 5.01±0.61 (4-6) mm in group 2 (P=0.212).
The mean MR recession in recession-resection procedure was 5.25±0.29 (5-6) mm
in group 1 and 4.86±0.75 (4-6) mm in group 2 (P=0.412). The mean amount of lateral rectus
(LR) resection was 6.01±0.82 (5-7) mm in group 1 and 5.82±1.16 (4.5-8) mm in
group 2 (P=0.648). The maximum amount of MR recession was 6.5 mm
in bilateral MR recession and it was performed in two patients in group 1.
Group 1 and group 2 were matched in terms of age of patient, preoperative near
and distance deviation and type and amount of strabismus surgery.
Table 1
incorporates data on preoperative and postoperative clinical characteristics in
both of the groups. The mean time for the
development of consecutive deviation in group 1 was 5.36±4.39 (2-15)mo whereas
the mean postoperative follow-up time in group 2 was 26.32±12.28 (15-56)mo.
Table 1 The
preoperative and postoperative clinical features of group 1 and group 2
|
Clinical
features |
Group 1 (n=14) |
Group 2 (n=31) |
P |
|
Preoperative
deviation [ |
|
||
|
Near |
42.51±13.69 (20-60) |
41.61±12.87 (20-70) |
0.835 |
|
Distance |
41.01±16.37 (8-60) |
40.58±13.26 (18-70) |
0.928 |
|
Postoperative
deviation [ |
|
||
|
Near |
16.79±10.24 (6-40) |
6.39±3.88 (0-10) |
0.002 |
|
Distance |
16.71±10.51 (6-40) |
5.94±3.81 (0-10) |
0.002 |
|
Postoperative convergence insufficiency |
4 (28.6%) |
- |
0.007 |
|
Neurological
diseases |
6 (42.9%) |
4 (12.9%) |
0.045 |
The visual
acuity could be evaluated in 10/14 patients of group 1 and in 16/31 patients of
group 2. The mean best corrected visual acuity for these patients was similar
(0.56±0.31 vs 0.76±0.22, P=0.072).
The mean refractive error as spherical equivalent was 1.66±0.98 (-3.75 to +3.25) D in group 1 and 2.16±1.28 (-3.25 to +6.50) D in group 2 (P=0.201).
There was no case of myopia of higher or equal than 6.00 D. The frequency of
myopia was higher in group 1 (42.9%, n=6 vs
6.5%, n=2, P=0.007).
The
amblyopia was observed in 7 patients in group 1 and in 7 patients in group 2 (P=0.110).
There was no patients with anisometropia in group 1 whereas 2 (6.5%, 2/31)
patients had anisometropia in group
2 (P=1.000). No complication related
to strabismus surgery was seen in any of the groups. The amount of preoperative near and distance deviation
was significantly reduced postoperatively in both groups (P<0.001 for all).
The systemic
diseases included cerebral palsy, mental retardation and epilepsy. Six patients
(42.9%) in group 1 and 4 patients (12.9%) in group 2 had neurological disorders
(P=0.045). When age at surgery, preoperative near and distance deviation,
amblyopia and anisometropia, the amount of MR recession and LR resection,
postoperative convergence, presence of systemic diseases and visual acuity were
all analyzed, presence of systemic disease was found to increase the risk of
consecutive deviation with an odds ratio equal to 5.75 (1.04-31.93).
DISCUSSION
In the
present study, we were able to demonstrate that associated neurological
disorders may compromise targeted postoperative outcome and may be among many
risk factors for the development of consecutive exotropia. Consecutive exotropia may occur after the
surgical correction of convergent strabismus as well as spontaneously or after
botulinum toxin injection[11-12]. The time of presentation is variable. Restriction in eye movements,
intractable diplopia, persistant large angle consecutive deviations, risk of
amblyopia or loss of binocularity may require prompt orthoptic and/or surgical
intervention for consecutive deviations. The targeted final outcome for
esotropia and exotropia is different in many aspects. Initial esodeviation may
be desirable after the surgical correction of intermittent exotropia in order
to prolong the duration of orthophoria[7,13-14]. Treatment
methods for the consecutive deviations comprise alternate occlusion, prismatic
glasses, Fresnel prisms, and finally surgery[8,15]. Botulinum toxin
injection has been reported to be effective in the treatment of consecutive
esotropia[9,16-17].
Postoperative
outcome after strabismus surgery may sometimes differ in two patients even if
the amount of preoperative deviation and the surgical plan are completely the
same. Thus, we aimed by conducting this study to determine the probable factors
contributing to the development of consecutive exotropia. Our purpose was not
the management of consecutive deviations but the risk factors for the
development of any amount of consecutive exotropia therefore any amount of
exodeviation was considered as consecutive deviation regardless of whether the
amount was.
There have
been studies about the risk factors for consecutive exotropia. The reported
mean interval between the initial and the final surgery for the correction of
over- or undercorrected deviations ranged between 10y and 29y[15,18]. The
patients in the present study experienced consecutive exodrift in a shorter
time course (5.36±4.39mo). However, it should be kept in mind that this time
period only points the time when consecutive exotropia is noticed.
Anisometropia, asymmetric surgery, amblyopia, restriction of adduction
postoperatively have been reported to be associated with the development of
consecutive exotropia[19]. In the
present study, 28.6% of patients in group 1 experienced convergence deficit of
some sort suggesting deficit in MR function whereas none of the patients in
group 2 had. However, it was not found to increase significantly the risk of
postoperative exodeviation in logistic regression analysis. It has been
postulated that stretched scar might be one of the reasons contributing to the
development of consecutive exodeviations[18]. In the present
study, the data about the management of consecutive deviation were kept beyond
the purpose of the study and we can not be sure about the results of a forced duction test and/or
surgical exploration indicating the presence of a slipped MR muscle.
Ganesh et al[5] investigated consecutive exotropia after
surgery for infantile esotropia, added multiple surgeries to the aforementioned
risk factors and found that age at onset, age at surgery and the amount of
surgery were not related significantly to the risk of consecutive exodeviation.
High
refractive errors may compromise the measurement of deviations and may cause
miscalculation of the surgical amounts[20]. In the present study, there was no significant difference among two
groups in terms of spherical equivalents but the frequency of myopia was higher
in group 1.
Amblyopia
appears to be associated with less favorable outcome and accounts for one of
the main factors predisposing overcorrection in the literature although it was
not found to be a risk factor in the present study. However, there is a
controversy about the contribution of amblyopia into the development process of
consecutive exotropia[10,20-23].
Concerning
the development of spontaneous consecutive exodeviation, early onset of
esotropia, hyperopia more than 5 D and altered binocular vision have been
reported as risk factors[11]. The occurrence of spontaneous consecutive exotropia has
been attributed to low AC/A ratio[21,24].
The
management of strabismus in patients with neurological impairment has been
studied in detail in the literature. Charles and Moore[25] compared the outcomes of strabismus surgery for infantile esotropia
with and without neurological problems and /or prematurity. They found similar
frequency of orthophoria in both groups and they recommend not to delay the
surgery for infants with neurological problems.
Bang and
Brodsky[26] reported that large angle exodeviations might be corrected by adjusted
surgical numbers in patients with neurological impairment. Hauviller et al[27] suggested that botulinum toxin injection might be the primary
treatment in esotropic children wih neurological impairment.
The present
study should be assessed in the setting of the following restrictions: at first, the number of patients in both of the
groups may cause the underestimation or the ignorance of other important risk
factors such as amblyopia and binocular function in this retrospective study.
Secondly, the neurological diseases reported in the study consist of epilepsy
and mental retardation with undetermined origin and we can not be sure about
their contribution to the deviation type and its amount. In addition, there was
no follow-up time for the consecutive group. The time recorded was the only
period when the consecutive deviation was noticed. We don’t know whether the
consecutive deviation was temporary or not. Furthermore, the interventions for
the correction of the consecutive deviations were beyond the purpose of the
study. Longer period for follow-up is necessary in order to assess the
persistence of the consecutive deviation. Longer follow-up time may introduce
some confounding factors as well. Data concerning the binocular status of the
patients as being one of the main factors providing ocular alignment, were not
precise for all patients and limited the interpretation of the findings. The
lack of further standardization of the surgery as a result of a retrospective
study creates another weakness in addition to the other points mentioned above.
This study
indicates and highlights the higher risk of postoperative consecutive
exotropia in patients with neurological diseases. It is apparent that careful
review of the generally used surgical amounts is required if a patient has
associated neurological problems.
The type and
the severity of neurological impairment that may lead the development of
consecutive exodeviation still remains as a matter of debate and may influence
the time of occurrence and the amount of consecutive deviation in respect with
the tonosity of extraocular muscles and sensorial control. Furthermore, the
results of the study may be extrapolated only for the mentioned age group. The
results of the present study can not be extrapolated to all patients with
neurological problems because we were not able to grade neither the severity of
the disease nor the association between the severity of the disease and the
frequency of consecutive deviation. It should be borne in mind that
accompanying neurological disorder may increase the risk of consecutive
deviation after esotropia surgery.
ACKNOWLEDGEMENTS
Conflicts of Interest: Taylan
Sekeroglu H, None; Erkan Turan K, None; Karakaya J, None; Sener EC, None; Sanac AS,
None.
REFERENCES
1 Mohan K, Sharma
A, Pandav SS. Unilateral lateral rectus muscle recession and medial rectus
muscle resection with or without advancement for postoperative consecutive
exotropia. J AAPOS
2006;10(3):220-224. [CrossRef]
[PubMed]
2 Yazawa K.
Postoperative exotropia. J Pediatr
Ophthalmol Strabismus 1981;18(1):58-64. [PubMed]
3 Stager DR,
Weakley DR Jr, Everett M, Birch EE. Delayed consecutive exotropia following
7-millimeter bilateral medial rectus recession for congenital esotropia. J Pediatr Ophthalmol Strabismus
1994;31(3):147-150. [PubMed]
4 Forrest MP,
Finnigan S, Finnigan S, Gole GA. Three horizontal muscle squint surgery for
large angle infantile esotropia. Clin
Experiment Ophthalmol 2003;31(6):509-516. [CrossRef] [PubMed]
5 Ganesh A,
Pirouznia S, Ganguly SS, Fagerholm P, Lithander J. Consecutive exotropia after
surgical treatment of childhood esotropia: a 40-year follow-up study. Acta Ophthalmol 2011;89(7):691-695. [CrossRef] [PubMed]
6 Cho YA, Kim SH.
Postoperative minimal overcorrection in the surgical management of intermittent
exotropia. Br J Ophthalmol
2013;97(7):866-869. [CrossRef] [PubMed]
7 Oh JY, Hwang
JM. Survival analysis of 365 patients with exotropia after surgery. Eye (Lond) 2006;20(11):1268-1272. [CrossRef] [PubMed]
8 Lee EK, Hwang
JM. Prismatic correction of consecutive esotropia in children after a
unilateral recession and resection procedure. Ophthalmology 2013;120(3):504-511. [CrossRef] [PubMed]
9 Couser NL,
Lambert SR. Botulinum toxin a treatment of consecutive esotropia in children. Strabismus 2012;20(4):158-161. [CrossRef] [PubMed] [PMC free article]
10 Donaldson MJ,
Forrest MP, Gole GA. The surgical management of consecutive exotropia. J AAPOS 2004;8(3):230-236. [CrossRef] [PubMed]
11 Senior JD,
Chandna A, O'Connor AR. Spontaneous consecutive exotropia in childhood. Strabismus 2009;17(1):33-36. [CrossRef] [PubMed]
12 Tejedor J,
Rodríguez JM. Management of nonresolving consecutive exotropia following
botulinum toxin treatment of childhood esotropia. Arch Ophthalmol 2007;125(9):1210-1213. [CrossRef] [PubMed]
13 Raab EL, Parks
MM. Recession of the lateral recti. Early and late postoperative alignments. Arch Ophthalmol 1969;82(2):203-208. [CrossRef] [PubMed]
14 Scott WE,
Keech R, Mash AJ. The postoperative results and stability of exodeviations. Arch Ophthalmol 1981;99(10):1814-1818. [CrossRef]
15 Ludwig IH,
Chow AY. Scar remodeling after strabismus surgery. J AAPOS 2000;4(6):326-333. [CrossRef] [PubMed]
16 Dawson EL,
Marshman WE, Lee JP. Role of botulinum toxin A in surgically overcorrected
exotropia. J AAPOS 1999;3(5):269-271.
[CrossRef]
17 Lawson JM,
Kousoulides L, Lee JP. Long-term results of botulinum toxin in consecutive and
secondary exotropia: outcome in patients initially treated with botulinum
toxin. J AAPOS 1998;2(4):195-200. [CrossRef]
18 Tinley C,
Evans S, McGrane D, Quinn A. Single medial rectus muscle advancement in
stretched scar consecutive exotropia. J
AAPOS 2010;14(2):120-123. [CrossRef] [PubMed]
19 Yurdakul NS,
Ugurlu S. Analysis of risk factors for consecutive exotropia and review of the
literature. J Pediatr Ophthalmol Strabismus 2013;50(5):268-273. [CrossRef] [PubMed]
20 Jang JH, Park
JM, Lee SJ. Factors predisposing to consecutive esotropia after surgery to
correct intermittent exotropia. Graefes
Arch Clin Exp Ophthalmol 2012;250(10):1485-1490. [CrossRef] [PubMed]
21 Weir CR,
Cleary M, Dutton GN. Spontaneous consecutive exotropia in children with motor
fusion. Br J Ophthalmol 2001;85(2):242-243. [CrossRef] [PubMed] [PMC free article]
22 Oguz V, Arvas
S, Yolar M, Kizilkaya M, Tolun H. Consecutive exotropia following strabismus
surgery. Ophthalmologica
2002;216(4):246-248. [CrossRef]
23 Folk ER,
Miller MT, Chapman L. Consecutive exotropia following surgery. Br J Ophthalmol 1983;67(8):546-548. [CrossRef]
24 Ciner EB,
Herzberg C. Optometric management of optically induced consecutive exotropia. J Am Optom Assoc 1992;63(4):266-271. [PubMed]
25 Charles SJ,
Moore AT. Results of early surgery for infantile esotropia in normal and
neurologically impaired infants. Eye
(Lond) 1992;6(Pt 6):603-606. [CrossRef] [PubMed]
26 Bang GM,
Brodsky MC. Neurological exotropia: do we need to decrease surgical dosing? Br J Ophthalmol 2013;97(2):241-243. [CrossRef] [PubMed]
27
Hauviller V, Gamio S, Sors MV. Essential infantile esotropia in neurologically
impaired pediatric patients: is botulinum toxin better primary treatment than
surgery? Binocul Vis Strabismus Q
2007;22(4):221-226. [PubMed]
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