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Intermittent Exotropia, OvercorrectingMinus Lenses, and the Newcastle Scoring
Systematrick Watts, MBBS, MS, FRCS, FRCOphth,a Emma Tippings, M.Med.Sci, B.Med.Sci, Cert Ed,a
nd Hasan Al-Madfai, BSc, MSc, PhDb
urpose: We sought to determine whether the Newcastle Control Score (NCS) could be used to indicate auccessful outcome in patients with intermittent exotropia that were treated with minus lenses. Methods: Wetudied patients with an intermittent exotropia who were prescribed minus lens therapy in an effort to manageheir strabismus conservatively. The NCS, which quantitatively estimates the control of an intermittent exotropia,
as applied before treatment and 4 months after treatment. The results of minus lens therapy with a pretreatmentCS of �5 (group 1) were compared with those with a NCS of �4 (group 2). Results: There were 24 patients (13irls, 11 boys) treated with minus lenses. The mean age of the patients was 6.8 � 3.8 years (range, 2-17 years;edian, 5). The mean pretreatment distance angle was 28.5 � 10 prism diopters (range, 6-45; median, 30) and theean post-treatment distance angle was 18.3 � 8.9 prism diopters (range, 0-35; median, 18) P � 0.001. Using theCS minus lenses significantly (P � 0.041) improved control of exotropia. In group 2 (n � 16) 75% had improved
cores post-treatment compared with 62.5% in group 1 (n � 8), P � 0.68. Conclusions: These data suggest thathe NCS is a useful method to indicate the success in the control of intermittent exotropia with conservative
reatment with minus lens therapy. (J AAPOS 2005;9:460-464)rdutsei
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recent systematic review of the surgical interven-tions for intermittent exotropia highlighted thecontroversies that still exist regarding the most ap-
ropriate treatment option.1 It has been recommended thatoth the frequency of the manifest deviation (observed50% of waking hours) and its size are important in makingdecision to intervene surgically.2 An exotropia �20 prismiopters (PD) with good binocular control for near generallys considered the threshold for surgical intervention withonsurgical treatment for smaller deviations.3
The condition may progress from an exophoriahrough an intermittent exotropia to a constant exotropiaith loss of binocularity.4 Therefore, timely surgery be-
ore the age of 7 years or the presence of strabismus foress than 5 years was reported to achieve superior sensoryutcomes.5
Surgery for intermittent exotropia has a 10-15% re-orted incidence of overcorrection with the loss of ste-
rom the aUniversity Hospital of Wales, Cardiff, and the bUniversity of Glamorgan,ales, United Kingdom.
resented as a poster at AAPOS 2004, Washington, DC.ubmitted November 17, 2004.evision accepted April 5, 2005.eprint requests: Mr Patrick Watts, Consultant Paediatric Ophthalmologist, University Hos-ital of Wales, Cardiff CF14 4XW, UK. (e-mail: [email protected]).opyright © 2005 by the American Association for Pediatric Ophthalmology andtrabismus.091-8531/2005/$35.00 � 0
coi:10.1016/j.jaapos.2005.04.010
60 October 2005
eoacuity6,7 and although the natural history of this con-ition is not fully known, some long-term observations onnoperated exotropia have reported 70% of distant exo-ropia to remain stable over the course of 11 years.4 Con-ervative treatment with prisms, occlusion, orthoptic ex-rcises, and minus lenses often have preceded surgicalntervention, especially for the smaller angles.8
The aim of any intervention in intermittent exotropia iso improve the misalignment of the visual axis in theistance while maintaining binocular single vision forear. The decision to intervene depends on subjectivearental observation and clinical assessment of control ofhe deviation. The introduction of a scoring system forntermittent exotropia, which includes parental observa-ions with objective assessments, allows the determinationf the severity of the exotropia.9 We report a pilot studysing the NCS scoring system to assess the efficacy ofonservative therapy with minus lenses in intermittentxotropia.
ATERIALS AND METHODS
he conservative management of intermittent exotropia inur institute is with overcorrecting minus lenses. TheCS was applied to those children treated with conserva-
ive therapy; hence, ethical approval was not required. Thearents were instructed to observe the control of the exo-ropia with the spectacles. Twenty-four patients with in-ermittent exotropia were studied consecutively. The in-
lusion criteria included those children with an intermit-Journal of AAPOS
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Journal of AAPOSVolume 9 Number 5 October 2005 Watts et al 461
ent exotropia noticed by the parents and an intermittentxotropia recorded with the cover test for distance. Aetailed history, which included the parental observationf the deviation, a full ophthalmic evaluation, and a cyclo-legic refraction, was conducted on all children. The oc-lar deviation was measured with an alternate cover test atm and 33 cm to an accommodative target. The scoring
ystem,9 which includes 3 components of home controlnd clinical control for near and distance, was applied toach of the subjects (Table 1).
All subjects were offered minus lens therapy to controlhe exotropia, which was conducted by adding the maxi-um tolerated minus lenses, with a minimum of minus 2
iopters to a maximum of minus 4 diopters, to their fullycloplegic refraction. Hence, if the subjects were hyper-etropic, the prescription was reduced by a minimum of 2
iopters to a maximum of 4 diopters. An emmetropicndividual for instance would be prescribed a minimum of
inus 2 diopters and a maximum of minus 4 diopters. Thetrength prescribed depended on their ability to read the0/20 and N5 (reading test type, Clement Clarke Ltd,ondon, UK) with the equivalent minus lenses in place.The scoring system was then reapplied after a minimum
eriod of refractive adaptation of 2 months. The subjectsere divided into 2 groups, those with a score of �5
group 1) and those with a score of �4 (group 2) beforeinus lens therapy. Data also were recorded on the com-
ABLE 1. The Newcastle Control Score9
ome control Score
1. Excellent – Strabismus/monocular eye closure nevernoticed
0
2. Good – Strabismus/monocular eye closure noticedrarely, only at distance, when fatigued, daydreamingor inattentive
1
3. Fair – Strabismus/monocular eye closure noticedfrequently (�50% waking hours) at distance but neverat near
2
4. Poor – Strabismus/monocular eye closure noticed atnear fixation
3
linic control: Cover test Rate of Recovery: Distance fixation1. Good – Breaks only after cover test and resumes
fusion without the need for blinkor refixation(heterophoria with good recovery)
0
2. Fair – Blink or refixate to control after cover test(heterophoria with delayed recovery)
1
3. Poor – Manifest spontaneously or without fusiondisruption, without recovery
2
linic control: Cover test Rate of Recovery: Near fixation1. Good – Breaks only after cover test and resumes
fusion without the need for blinkor refixation(heterophoria with good recovery)
0
2. Fair – Blink or refixate to control after cover test(heterophoria with delayed recovery)
1
3. Poor – Manifest spontaneously or without fusiondisruption, without recovery
2
liance of spectacle wear. Overcorrected minus lenses t
ere discontinued if there was no improvement on 2uccessive visits during a period of 4 months.
The preintervention scores without minus lenses werehen compared with the postintervention scores at 3onths. In group 1, a successful outcome was judged by a
eduction of their preintervention score to 4 or less and inroup 2 a successful outcome was judged by any reductionf their preintervention score, as a score of greater than 4as chosen to suggest the need for surgical intervention.Statistical analysis was conducted using a chi-square
oodness of fit to test the success of control of intermittentxotropia with minus lenses based on the scoring system.he Fisher exact test for independence, together with apearman’s correlation coefficient, was used to test foruccess in the 2 groups and to see whether the age, gender,nd size of the measured deviation impacted on the per-entage of those with a successful outcome.
ESULTS
here were 24 patients with intermittent exotropia treatedith minus lenses; 13 were girls. Group 1 (NCS score 5 to) had 8 patients and group 2 (NCS score 1 to 4) consistedf 16 patients. All patients had either a manifest exotropiar were intermittently manifest on a cover test at 6 m andad an exophoria or intermittent exotropia on cover test at3 cm. The exotropia measured with a prism cover test atm was greater than the exotropia or exophoria measured at3 cm by 10 PD in 16 patients, in 7 patients the measure-ents were the same for near and distance, and in 1 patient,
he near measurement exceeded the distance measurement.he cycloplegic refraction in the majority of patients (95%)as hypermetropic.The accommodative convergence to accommodation
atio (AC/A) measured by the disparity method was highn 1 patient. The mean age of the patients was 6.8 � 3.8ears (range, 2 to 17 years with a median of 5 years). Theean pre- and post-treatment angles for distant exotropiaere 28.5 � 10 PD (range, 6 to 45 PD with a median of0 PD) and 18.3 � 8.9 PD (range, 0 to 35 PD with aedian of 18 PD; P � 0.001; Table 1). NCS demonstrated
0.8% of the whole group had improved at 3 months (P �.04). There was a 62.5% improvement in the NCS inroup 1 and a 75% improvement in group 2 (P � 0.68;able 2). The details of the change in each component of
he NCS with minus lens for each patient are listed inable 3. Subjects in group 2 received a mean treatment ofinus 2.7 diopters and those in group 1 received minus 2.2
iopters, assuming normality and random sampling, thisifference is statistically significant (P � 0.008). Thepearman correlation coefficient between the reduction inhe NCS and the strength of the minus lenses prescribedn the sample was –0.47 (P � 0.02). There was no effect ofhe gender (P � 0.18), the size of the deviation at nearP � 0.1), or distance (P � 0.8) and success measured by
he reduction of the NCS.
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Journal of AAPOSVolume 9 Number 5 October 2005462 Watts et al
ISCUSSION
he aim of overcorrecting minus lenses is to stimulateccommodative convergence to control intermittent exo-ropia. It has been shown to improve both qualitativebservations and quantitative measurements. In our study,hen we used the NCS, 70.8% of patients showed an
mprovement in the exotropia control. This scoring sys-em, which has been validated, incorporates parental ob-ervation and objective cover test assessment at near andistance.9 On the basis of this system, it was suggested thatscore equal or greater than 3 was the threshold for
urgical intervention. Alternative threshold scores may besed, and individual centers may choose a higher scoreased on their study population. For the purpose of thistudy, we chose a score equal or greater than 4 as thresholdor surgical intervention because we felt that the maximumome control of 3 alone could not be justification for
ntervention. The division of the scoring system based onthreshold score for surgical intervention for this studyas done to separate those with poor (group 1) control
rom those with better control (group 2) before minus lensherapy and to assess whether those in group 1 would noonger be candidates for surgical intervention after minusens therapy.
The 12.5% difference observed in the 2 groups woulduggest that small exotropias (group 2) have a greatermprovement in the NCS; however, this difference wasot statistically significant. It is not possible to draw any
ABLE 2. Intermittent exotropia treated with minus lenses and the Newc
GroupAge
(years)
Sex(Male � 1
Female � 2)
Equivalenmyopic
correction
8 1 �2.57 2 �2.55 1 �2.52 1 �2.57 1 �25 2 �3
17 2 �43 1 �2.57 2 �25 1 �2
10 2 �22 2 �24 1 �39 2 �2
11 2 �23 1 �25 2 �1.57 1 �35 1 �2.53 1 �29 2 �22 2 �24 2 �2
14 2 �2.5
onclusions from this difference because of the small sam- c
le size when divided into groups and, furthermore, aigher minus lens, used in group 1, may have lead toreater improvement of the NCS.
Our data have shown that 72% of children with inter-ittent exotropia had an improved status while still wear-
ng overcorrecting minus lenses. A period of observationfter discontinuing minus lens wear was not conductedecause the follow up was short (4 months) and objectivef this work was to assess, using the NCS, control ofntermittent exotropia with minus lenses. A previous studyeported 70% of cases maintaining long-term control afteriscontinuing overcorrecting minus lenses, which wereorn for a period of 12 to 18 months.8 The NCS was
pplied after a period of 4 months of minus lens therapy.here are important differences in the study populations,
g, the majority in our study population were hyper-etropic, and the AC/A ratio of 70% in their group was
igh compared with 8% in our cohort. In addition, al-hough the success rates reported are similar, our studyssessed the short-term success as judged with an objectivecoring system as opposed to the long-term reported con-rol after discontinuing minus lenses. Three patients inur study (numbers 2, 7, and 8) with high hypermetropiaere treated with a reduction in their spectacle prescrip-
ion (equivalent minus lens of minus 2.5 diopters to minusdiopters; Table 2).The follow-up in our study was too short to document
change in the refractive error or a progression to in-
ontrol Score (NCS)
Pretreatmentdistant angle
Post-treatmentdistant angle
Pretreatmentnear angle
35 20 2535 18 1230 25 3540 0 3520 20 3040 25 2540 10 5035 14 1616 16 1020 16 045 8 3035 35 030 20 2014 8 818 16 1825 14 2520 30 1435 18 1840 30 4035 35 1225 12 186 6 12
25 25 2520 18 12
astle Ct
reased myopia with overcorrected minus lenses; however,
T
T
1
2
Journal of AAPOSVolume 9 Number 5 October 2005 Watts et al 463
ABLE 2. Continued
Post-treatmentnear angle
NCSpretreatment
NCSpost-treatment
Outcome(Success � 1Failure � 2)
Pretreatmentrefraction (R)
Pretreatmentrefraction (L)
18 5 4 2 �1.50/�2.00�10 �1.5018 5 2 1 �6.50 �6.5025 6 6 2 �1.25 �1.00
�14 6 0 1 �1.50 �1.5025 6 6 2 1.25/0.75�180 2.00/�1.25�17016 5 2 1 �2.00 �2.0012 7 1 1 �7.00 �8.258 5 1 1 �5.00 �5.00
10 2 0 1 plano 0/�0.5�10�1 2 0 1 �1.00 �1.0015 4 2 1 �0.75 �1.50/�0.25�90
0 4 3 1 plano plano14 3 2 1 �1.75 �1.752 2 0 1 0.0 0.0
14 4 1 1 �0.25 �0.258 3 2 1 �0.75 �0.75
14 3 4 2 �1.25 �1.258 3 0 1 �1.25/0.25�180 �1.25/0.25�180
25 3 3 2 �1.00 �1.5025 4 4 2 �0.25/�0.5�100 �0.25/�0.5�9512 3 0 1 �0.25 �0.2516 0 0 1 �0.50 �0.5025 4 4 2 �1.00/�0.75�90 �1.00/�0.75�90
9 3 0 1 �1.25 �1.25
ABLE 3. Newcastle Control score with and without minus lens
Group No.
Without minus correction
Total
With minus correction
TotalHome Near Distance Home Near Distance
1 2 1 2 5 1 1 2 42 1 2 2 5 0 1 1 23 3 1 2 6 3 1 2 64 3 1 2 6 0 0 0 05 2 2 2 6 2 2 2 66 1 2 2 5 0 0 1 17 3 2 2 7 1 0 0 18 1 2 1 4 2 0 0 21 1 0 1 2 0 0 0 02 1 0 1 2 0 0 0 03 1 1 2 4 1 0 1 24 2 0 2 4 2 0 1 35 2 1 1 4 1 1 1 36 1 0 1 2 0 0 0 07 2 1 1 4 1 0 0 18 1 0 2 3 0 0 2 29 2 0 2 4 0 0 2 2
10 1 0 2 3 0 0 0 011 1 1 1 3 1 1 1 312 1 1 2 4 1 1 2 413 1 1 1 3 0 0 0 014 0 0 0 0 0 0 0 015 1 1 2 4 1 1 2 4
16 1 0 2 3 0 0 0 0
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Journal of AAPOSVolume 9 Number 5 October 2005464 Watts et al
previous study has shown that treatment of intermittentxotropia with overcorrecting minus lenses does not leado increased myopia with long-term follow-up.10
The NCS, which has reported good interobserver re-iability,9 was clinically easy to apply and is better suited toeflect the control of the exotropia than the actual mea-ured deviations by the alternate cover test. There was noifficulty in the physician’s ability to assess the control ofxotropia or to apply the NCS in this cohort of patients. Itrovides an objective score that reflects the control ofxotropia before and after conservative treatment withvercorrecting minus lenses. It can be argued that the im-rovement in the NCS is entirely caused by improvement inome control, as parental observation of an exotropia withinus lens may be not be as accurate as without spectacles.able 3, however, shows that parental observation correlatedell with clinical examination.The drawback of this study is the absence of a control
roup. However, none of our cases demonstrated a ten-ency for improvement in the control of their exotropia 6onths before the institution of overcorrecting minus
enses. Although the sample size was small and the NCSas not able to differentiate those individuals most likely
o respond to minus lens therapy, it shows that the size ofhe exotropia is not a prerequisite for a successful outcome.
he NCS indicates only the control of the exotropia andoes not lend itself to indicate a reduction in the angle ofxotropia induced with overcorrecting minus lenses. De-pite its limitations, it demonstrates that the NCS is aseful method to gauge the response of conservative treat-ent for intermittent exotropia with overcorrecting minus
enses.
References1. Richardson S, Gnanaraj L. Interventions for intermittent distance
exotropia. Cochrane Database Syst Rev 2003:CD003737.2. Von Noorden GK, Campos EC. Exodeviations. In: Lampert R,
editor. Biocular vision and ocular motility; theory and managementof strabismus. St Louis, MO: Mosby; 2002, pp 356-76.
3. Cooper JMN. Intermittent exotropia basic and divergence excess(major review). Binocul Vis Strabismus Q 1993;8:185-216.
4. Hiles DA, Davies GT, Costenbader FD. Long-term observations onunoperated intermittent exotropia. Arch Ophthalmol 1968;80:436-42.
5. Abroms AD, Mohney BG, Rush DP, Parks MM, Tong PY. Timelysurgery in intermittent exotropia for superior sensory outcome. Am JOphthalmol 2001;131:111-6.
6. McDonald RJ. Secondary exotropia. Am Orthop J 1970;20:91-5.7. Pratt-Johnson JA, Barlow JM, Tillson G. Early surgery in intermit-
tent exotropia. Am J Ophthalmol 1977;84:689-94.8. Caltrider N, Jampolsky A. Overcorrecting minus lens therapy for treat-
ment of intermittent exotropia. Ophthalmology 1983;90:1160-5.9. Haggerty H, Richardson S, Hrisos S, Strong NP, Clarke MP. The
Newcastle control score: a new method of grading the severity ofintermittent distance exotropia. Br J Ophthalmol 2004;88:233-5.
0. Kushner BJ. Does overcorrecting minus lens therapy for intermittent
exotropia cause myopia? Arch Ophthalmol 1999;117:638-42.An Eye on the Arts – The Arts on the Eye
Padre Buonconte passed through the thinning crowd in the Via VecchiaPoggioreale a changed man. He staggered back to the chiesa and prostratedhimself on the floor before the altar in silent discourse with the Lord. His agedframe throbbed with pain. The following morning the sexton found him there,stiff and cold, and though long dead, his eyes still poured forth tears.
This phenomenon came to be known as Padre Buonconte’s miracle, and itwas not long before a cult developed and hordes of the faithful were flocking tothe chiesa to see the tears for themselves. Even after the interment of the corpsein the crypt, the tears continued to well up and form a pool on the floor of thechurch. The tears were held to have healing properties, and pilgrims traveledfrom as far afield as Salerno and Avellino to immerse their gangrenous legs andulcerated armpits in the pozza dolorosa. Amalasunta Castorelli, as befits a womanof commerce, was not slow to set up a stall outside the church, where sheoffered for sale vials of bogus tears, and in the cult’s heyday she was selling outof her stocks faster than her husband could draw up the brackish water from thewell.
—Lily Prior (from Nectar, HarperCollins)
