Ocular morbidity on headache ruled out of systemic causes

www.journalofoptometry.org

ORIGINAL ARTICLE

Ocular morbidity on headache ruled out of systemic causes----A prevalence study carried out at a community based hospital in Nepal

Sanjay Marasini

^a,∗

, Jyoti Khadka

^b

, Purnima Raj Karnikar Sthapit

^a

, Ranjana Sharma

^a

, Bhagvat Prasad Nepal

^a

aDepartmentofOphthalmology,DhulikhelHospital,KathmanduUniversityHospital,Dhulikhel,Nepal

bSchoolofOptometryandVisionScience,FlindersUniversity,BedfordPark,Australia

Received27November2011;accepted20January2012 Availableonline31March2012

KEYWORDS Binocularvision anomalies;

Convergence insufficiency;

Headache;

Refractiveerrors

Abstract

Purpose:Theassociationbetweenophthalmicanomaliesandheadachestillneedstobeinves- tigatedlargely.WeaimedtolookforitinthecontextofaruralcommunityhospitalofNepal.

Methods:Hundredpatientswithheadachewereinvestigatedfor ophthalmicanomaliesafter theprobablesystemicassociationwasruledout.Allthepatientswerefirstexaminedbygen- eralphysician,otorhinolaryngologistandpsychiatrist.Ocularevaluationconsistedofdetailed refractive,binocularityassessmentandanteriorandposteriorsegmentexamination.Datawere analyzedusingt-test, chi-squaretest,multiplelogisticregression, oddsratioaswellasfre- quencyandpercentages.

Results:Femaleabovetheageof17sufferedmore(p<0.05).Frontalheadachewasmorecom- monthanoccipital(p>0.05).Instudentsandhousewivesfrontalheadachewasmorecommon (OR3.467,0.848---14.174;95%CIand1.167,0.303---4.499;95%CI).Refractiveerrorwasassoci- atedwithfrontalheadache(OR,1.429,1.130---0.806,95%CI).Onpresentation,88%hadvisual acuity6/9orbetter.Forty-fourpercenthadrefractiveerroramongwhomastigmatismwasmore frequent (63.63%)followedby hyperopia(27.27%)andmyopia(9.09%).Known eyeproblems weresignificantlyassociatedwithrefractiveerrorandbinocularvisionanomalies(p<0.001).

Convergenceinsufficiency(16.25%)andfusionalvergence(11.25%)deficiencieswerecommon amongunstablebinocularity.

Conclusion:Ocular anomalies co-exist withheadache complainsvery frequently. Refractive andbinocularvisionanomaliesneedtobelargelyinvestigatedinallheadachepatients.Itis importanttogetagoodheadachehistorysothatpatientscanbereferredtotheappropriate specialist.

© 2011Spanish GeneralCouncil ofOptometry. Publishedby ElsevierEspaña, S.L.All rights reserved.

∗Correspondingauthor.

E-mailaddress:thesanzay@gmail.com(S.Marasini).

1888-4296/$–seefrontmatter©2011SpanishGeneralCouncilofOptometry.PublishedbyElsevierEspaña,S.L.Allrightsreserved.

doi:10.1016/j.optom.2012.02.007

PALABRASCLAVE Anomalíasdevisión binocular;

Insuficienciade convergencia;

Cefalea;

Erroresderefracción

Morbilidadocularsobrecefaleadescartadaentrelascausassistémicas:estudiode prevalenciallevadoacaboenunhospitaldeunacomunidadenNepal

Resumen

Objetivo: Laasociaciónentreanomalíasoftálmicasycefaleatodavíadebeinvestigarseafondo.

NuestroobjetivofueexaminarloenelcontextodeunhospitaldeunacomunidadruraldeNepal.

Métodos: Se examinaron cien pacientescon cefalea enbusca de anomalías oftálmicas una vez descartada unaposible asociaciónsistémica.Todoslospacientesfueron exploradospor unmédicogeneral,unotorrinolaringólogoyunpsiquiatra.Laevaluaciónocularconsistióenun examendetalladorefractivodelabinocularidadyunexamendelsegmentoanterioryposterior.

Losdatosseanalizaronutilizandolapruebadelat,lapruebadela␹²alcuadrado,regresión logísticamúltiple,razóndeprobabilidades,asícomofrecuenciayporcentajes.

Resultados: Lasmujeresmayoresde17 a˜nossufrieronmás(p<0,05).Lacefaleafrontalfue másfrecuentequelaoccipital(p>0,05).Enestudiantesyamasdecasafuemásfrecuentela cefaleafrontal(OR3,467,0,848 -14,174;ICdel95%y1,167,0,303-4,499;ICdel95%).El errorderefracciónseasoció concefaleafrontal(OR,1,429,1,130-0,806,ICdel95%).Enla presentación,el88%teníanunaagudezavisualde6/9omejor.Un40%presentaronerroresde refracción,entreloscualeselmásfrecuentefueastigmatismo(63,63%),hipermetropía(27,27%) ymiopía(9,09%).Losproblemasocularesconocidosseasociarondemanerasignificativacon errorderefracciónyanomalíasdevisiónbinocular(p<0,001).Lainsuficienciadeconvergencia (16,25%)ylosdéficitsdevergenciafusional(11,25%)fueronfrecuentesenlavisiónbinocular inestable.

Conclusión: Lasanomalíasocularescoexistenmuyfrecuentementeconcasosdecefalea.Las anomalíasderefracciónydevisiónbinoculardebeninvestigarseafondoentodoslospacientes concefalea.Esimportanteobtenerbuenosantecedentesdecefaleaparapoderremitiralos pacientesalespecialistaadecuado.

©2011Spanish GeneralCouncilofOptometry.Publicado porElsevierEspaña,S.L.Todoslos derechosreservados.

Introduction

Headachehasbeendefinedasthepainlocatedaboveorbit- omeatal line.¹ Itis one ofthe frequent reasonstoseek a consultationwithhealthcarepractitioners.²Itisadifficult conditiontoestablishtheactualcause.Diagnosisandtreat- mentisoftenanimpossibletaskwithoutthecorrectviews ofetiology.³

Primary headache (headache without underlying disor- ders)prevalencevarieswithage,9---11%inschoolchildren.⁴ Thepreponderanceofheadacheishigherinfemale.Inmore than 80% patients, headache starts beforeage 40 with a lowerprevalencerateatanadvancedage(>50years).⁵Sim- ilarly, highly conflicting prevalence has been observed in differentcountriesas21.2% inthe US,⁶ 96%in Denmark,⁷ andpast-yearprevalencerangesfrom13.4%intheUS,⁶to 87.3%inCanada.⁸

The evidence in the literature for a strong associa- tionbetweenoculo-visualproblemsandheadacheisweak.² Still patients who believe that appropriate ocular exam- ination and treatment help to lessen their headache visitoptometrists’andophthalmologists’veryfrequently.^8,9 Headache being one of the most common neurological symptomshas often been associated withParkinson’sdis- ease, multiple sclerosis andmyasthenia gravis. Nishimoto etal.revealed thatinheadacheassociatedwithmyasthe- niagravis,mildocularsymptomsareassociatedwhichrange from slight degree of diplopia or ptosis which fluctuates dynamicallyandmightleadtotheworseningofheadache.¹⁰

Harle and Evans report that in migraine headache often binocular vision anomalies in the formof decompensated heterophoria and reduced stereopsis might be present in subtleform.²

Ophthalmological studies on headache have reported theroleof differentocular diseases like acuteglaucoma, uveitis,opticneuritis¹¹andvisualanomalieslikerefractive errorsandaccommodativeandvergencedeficiencies.¹²The uncorrectedrefractiveerrorsareoftenbelievedtobeasso- ciatedwithfrontaland/oroccipitalheadache.¹³Eyestrain asa directcauseofheadachehas longbeen debated.^14,15 Very frequently a careful eye examination and a possi- blecorrectionof thedefect hasbeen observed toreduce headachesymptoms.¹Thomasetal.notedthat21%ofpeo- plewithheadacheconsultaneyecarepractitionerwhichis almostsimilartothose(27%)whoseekaconsultationwith ageneralmedicalpractitioner.⁹Whittingtonreportedthat amongmore than1400 consecutivepatients attendingfor refraction,45%complainedofheadache.¹⁶

PatientswhofailSheard’scriterion(Prism FusionalVer- gence less than twice the near phoria) are expected to sufferfromheadachesymptoms.¹⁷ In1966,Gordonetal.¹⁸ claimedthatminorrefractiveerror(RE)oftencausedmore headacheandsymptomsofeyestrainthanmajorRE.Ciliary musclestrainhasalsobeensuggestedaspossiblesourceof headache.¹⁹Totheauthors’knowledge,therehasnotbeen anyreportsonexploringtheophthalmicshareofheadache symptomsamongtheNepalesepeoplewhopresenttoagen- eralhospital.

The aim of this study was to investigate whether reported headache complaints of patients attending the general ophthalmic clinic are associated with ophthalmic anomalies.

Methods

Patients

This studyhas a descriptivecross-sectionaldesign. It was conductedin the OphthalmologyDepartmentof Dhulikhel HospitaloveraperiodofthreemonthsfromMarch2010.The hospitalcovers the ruralpopulation of approximately1.9 million people from Kavrepalanchowk, Sindhu-palchowk, Dolakha, Sindhuli, Ramechhap, Bhaktapur and other sur- rounding districts. Hospital targets mainly the people with low socio-economic status who do not have access to the well facilitated health care services. It has pro- videdservices to 50 out of 75 districts of the country so far.²⁰

Weincludedonlythepatientswithheadachewhowere referredfromthemedical,otorhinolaringology(ENT)orpsy- chiatry Out Patient Department (OPD). The diagnosis of primary headache was based on International Classifica- tionofHeadacheDisorders:2ndedition(ICHD-II),basedon physicalandneurologicalexaminationsandheadCTand/or MRI.Criteria for eye consultationwere set asfollows:all thepatients needed toundergo thoroughsystemic evalu- ationwith appropriatetests carried out.The appropriate investigationwasordered by the respectivedepartments.

Thepatientswithoutdefinite diagnosiswerethenreferred for eye examination. Only the patients withheadache of more than three months duration were included in the study.

Each alternate patient complaining of headache (irre- spectiveofnature/location/intensity)wasincluded inthe study with unrestricted random sampling method regard- less of age, sex and referral. Alternate patients were chosen because it gave a plenty of time for the exami- nation to be carried out in each patient in detail. Blood pressurewasmeasuredineachpatienttolookforundiag- nosedhypertension.Noneofthepatientshadundiagnosed hypertension.Patients withother diagnosed systemic dis- eases such as migraine, sinusitis, and dental caries or womenwithmenstrualmigraineand/orwomentakingoral contraceptive pills were excluded from the study. Age groupsofthepatientswerecategorizedasschoolchildren (<17 years), non-presbyopic adults (<40 years) and pres- byopic adults(>40 years).This researchwasapproved by the institutional research committee of Dhulikhel Hospi- tal.The tenetsof theHelsinkideclarationwerefollowed.

Fullinformedconsentwasobtainedandparticipantswere able to abstain or withdraw from the research at any time without having to give a reason. No participants withdrew after they had arrived at the clinic. It was ensured that the clinician was masked about the iden- tity of the patients with headache participating in the study and those excluded from the study,so that all the tests would be performed with equal emphasis to every patient.

Assessments

Headachequestionnaires

The firstpart of the evaluation consisted of a structured interviewconductedbyoneofthemedicalinternsanduti- lizing a headachequestionnaire. The questionnaireswere basedonanarticle‘‘Howtotakeahistoryofheadorfacial pain’’byBlau.²¹Thequestionnairessurveyeddemographic data (e.g. sex, age, and occupation), headache occur- rence and characteristics, headache onset and timetable (categorizedintomorning,afternoon, evening,during the night,ornone)andpaintopography(categorizedintoback, front, leftsided, right sided or diffuse). The presence or absenceofaccompanyingsymptoms(nausea,vomiting,pho- tophobia, phonophobia) and visual aura were assayed, as were treatment patterns (non-pharmacological measures or medications or spectacles), the presence or absence ofaggravatingfactors(includingphysicalor visualeffort), family history, history of trauma, dentalcaries, sinusitis, menstrual disturbancesandoral contraceptivepillsintake infemales.

Patients were asked to estimate the average number of hoursspentdailyin visuallystrainingtasks (e.g.,read- ing,watchingtelevision,andworkingwithacomputer)and whetherheadachesaccompaniedthosetasks.

Visualacuityassessment

Presenting visual acuity was measured for each eye and for both eyes together at distance (6m) with internally illuminated Snellen’s Chart. Near vision was recorded at a distance of 33cm with good illumination with reduced Snellen’sChart.

Refractiveassessment

Retinoscopy was done with a retinoscope at the working distance of 50cm estimating refractive status of patients objectively, which was followed by subjective refraction in which the patient’s response to the corrective lenses wasassessed.Patientswithdissimilarobjectiveandsubjec- tive findings,fluctuatingrefractivestatus,below 15years ofage,andpatientswithbinocularvisionanomalies (BVA) underwentcycloplegic retinoscopy(1%cyclopentolate). In these patientssubjective refraction was done afterthree days,whenthecycloplegiaeffectdissapearedcompletely.

Spherical andastigmatic deviationsweremeasured tothe nearest 0.50 D. Astigmatic axes were measured to the nearestfivedegrees,negativecylindersbeingusedfor all measurements.Thedegreeofametropiawasstatedasfol- lows: patients with Spherical Equivalent Refractive Error (SERE) of −0.25 and +0.25 Dioptres (D) were considered asemmetropic,SERE>+0.50Dwasconsideredashyperopia andSERE>−0.50Dwasconsideredasmyopia.Astigmatism wasdefinedasthecylindricalcomponentoftherefractive errormorethan0.50D.Allexaminationswerecarriedout bythesingleobserver(optometrist),whodidnotknowthe resultsoftheheadachequestionnaire.

BinocularVisionAssessment(BVA)

Covertestwasperformedatadistanceof6mand40cmwith anopaqueoccluder.Asmallnon-accommodativetargetwas usedtocontrolaccommodation.The typeanddirectionof

heterophoriaorheterotropiawererecorded.Ocularmotor functions were evaluatedin six cardinal gazes. The Near Pointof Convergence (NPC,which is thenearest distance fromtheeyestowhicheyescanconvergewithout experi- encingdiplopiaorsubjectivediscomfort)wasassessedwith aRoyalAirForce(RAF)rule(aninstrumentusedtomeasure NPCandaccommodativeamplitude).AmplitudeofAccom- modation(AA,itisthedifferenceinthefocuspowerofthe eyewhile fixatingfromneartofar)wasmeasuredineach eyeseparatelyandbinocularlylaterwithpushupmethod.

Thefirstsustainedblurwasthennoted(thecarrierof the RAF rule which contains N series letter target is moved toward the patient resting the rule pad on cheeks. The patientisaskedtostatewhenlettersbecomeblurred;the firstsustainedblurisnotedasthedioptricdistancefromthe eye.).

BinocularVisionAssessment(BVA)exceptcovertestwas not carried out onpresbyopes because they areassumed todemonstratevergencedysfunctionduetolossofaccom- modative convergence. Fusional reserves were measured witha verticalbarprism usingan accommodative target.

Distancedivergent(base-in)followedbyconvergent(base- out)reserveswererecordedasthreevalues,theblurpoint, thebreakpoint,andtherecoverypoint.Nearbase-in and base-outfusionalreserveswererecordedinthesameway.

Heterophoria wasmeasured first, followed by divergence amplitudesandthenconvergenceamplitudes sothateach testdidnothaveeffectonother.

Otherexaminations

Slit lamp bimicroscopy and detailed fundus examination werecarried outtoruleout ocular pathology.Intraocular pressurewasmeasuredwithGoldmanntonometeronallthe patients.Patientswhosediagnosisremainedinconclusiveon eyeexaminationwerereferredtootherdepartmentssuch asmedical, ENTor psychiatry asrequired andelicitedby headachehistoryforfurtherinvestigation.¹

Dataanalysis

Fordata analysiswe included only theright eye in every patientwhenthereweretworeadingsfortwoeyesbecause findings inboth the eyesof sameindividual aregenerally likelytobesimilar.²²Statisticalanalysiswasdonebycalcu- latingt-testtocomparethemeansoftwogroups,chi-square test for non parametric data, multiple logistic regression toexplorerelationshipbetweenheadacheandoccupation, oddsratiotoexplorerisk ofheadachesitewithrefractive andbinocularitystatusaswellasfrequencyandpercentage to estimate the prevalence. Statistical software ‘Statisti- calPackageforSocial Sciences,version-11.5’wasusedto analyzedata.Statisticalsignificancewassetatp<0.05.

Results

Studypopulation

A total of 100 patients with headachecomplaints partic- ipated in the study. Non-participation was due to severe

Table 1 Reported headache with age,sex and previous examination(N=100).

Agegroup(years) Sex(no.) Previousexamination(%)

Male Female Yes No

<17 11 9 14 6

<40 18 42 33 22

>40 8 12 12 13

Total 37 63 59 41

headachewhilepresenting totheOPD.Fewpatientswere excludedbecauseofthesystemicdiseasesunderinvestiga- tionand which required simultaneous ocular consultation (likeHypertension,raisedintracranialpressure,pregnancy induced migraine, suspected sinusitis, menstrual distur- bances).Femalegenderpredominatedinthestudy(63%).

Agedistributionandpreviouseyeexamination

Mostof the headache complaintswere in non presbyopic adultswithfemales’outnumberingmalesineachagecate- gory,exceptforschoolchildren(Table1).Fifty-ninepercent ofthepatientshadpreviouseyeexaminationamongwhich 41%hadocularmorbidities.Twenty-fourpatients(24%)had previouseyeexaminationwithinsixmonths.Thefemalepre- ponderanceis not significant for the age below 17 years (²2=5.538, p=0.063) but it is highly significant for age above17years(p=0.026).

Profileofheadache

In 35% people headache lasted for one year. Some com- plainedoflong standingheadache ofmore thanone year evenlastinguptonineyears(onepatient).Thepatternof headachesitewiththeoccupationispresentedinTable2.

In multiple logistic regressions, we observed that the frontalandoccipitalheadacheisrelativelydeterminantfor bothstudentsandhousewives(Table3).Itisseenthatthe unstructuredoddsratiowassignificantwiththeoccupations andsiteofheadachebutthepvalueismorethan0.05.

Previouseyeexaminationwasobservedtobeariskfactor bothforrefractiveerror;OR1.213(0.924---1.593,95%CI)and binocularvisionanomalies;OR3.97(0.111---1.417in95%CI).

SixandsevenpatientseachwithREcomplainedoftemporal anddiffuseheadacherespectively.InfourpatientswithBVA diffuseheadachewaspresent.UncorrectedREwasobserved to be a risk factor for frontal headache (Table 4). None

Table 2 Percentagesof reportedsiteof headache com- plainswithoccupation(N=100).

Occupation Frontal Occipital Temporal Diffuse Total

Students 26 6 3 5 40

Housewife 14 9 5 8 36

Others 9 5 4 6 24

Total 49 20 12 19 100

Table3 Relationbetweenoccupationandsiteofheadache(formostfrequentlyobservedvalues).

Occupation Siteofheadache Statistics

pvalue Unstandardizedcoefficient Oddsratio(95%CI)

Students Frontal 0.084 1.243 3.467(0.848---14.174)

Occipital 0.670 0.365 1.440(0.269---7.714)

Temporal 0.914 −0.105 0.900 (0.133---6.080)

Housewives Frontal 0.823 0.154 1.167 (0.303---4.499)

Occipital 0.699 0.300 1.350 (0.295---6.183)

Temporal 0.940 −0.065 0.938(0.173---5.070)

Table4 Statisticalrelationbetweenoculo-visualanomalyandreportedsiteofheadache.ThestatisticsincludesPearson² testsandoddsratiowith95%confidenceinterval(CI).

Ocularanomaly Siteofheadache Statistics

Frontal Occipital Total Oddsratio(95%CI) p-Value

BVA 5 0 5 1.429(1.130---1.806) 0.155

RE 22 9 31

BVA,binocularvisionanomalies;RE,refractiveerror.

ofthe patientshadBVA leadingtooccipitalandtemporal headache.

Visualacuityandrefractiveexamination

Mostofthepatientshadnormaltosubnormalvisualacuity (Table5).Forty-fourpercentofthepatientshadrefractive error. All of them were corrected with appropriate pres- criptionwhichwasevidentthroughretinoscopy.Knowneye problemwas significantly associatedwith refractiveerror andBSVanomalies(²1=11.225,p=0.001).Eightearlypres- byopeswereprescribedthenearvisionglasses.

Table5 Summarytable.

Ocularmorbidity Frequency(%)

Visualacuity 100(100)

6/6---6/9 88(88)

6/12---6/60 10(10)

<6/60 2(2)

Refractiveerror 44(44.00)

Hyperopia 12(27.27)

Myopia 4(9.09)

Astigmatism 28(63.63)

Binocularvisionanomalies(nonpresbyopic, N=80)

23(28.75) Convergenceinsufficiency 13(16.25)

Poorfusionalvergence 9(11.25)

Intermittentexotropia 1(1.25)

Others 7(7)

CVS 5(5)

Establishedglaucoma 1(1)

Glaucomasuspect 1(1)

BinocularVisionAssessment(BVA)

Orthopticexaminationwascarriedouton80non-presbyopic patients (Table 5). Seventy-one patients hadorthophoria;

eighthadexophoriawithgoodrecovery.Fusionalvergence satisfyingSheard’scriteriawasmeasuredin71(89%).

Discussion

The prevalence of refractiveerrors (44%)in this group of thiscommunitywashigherthanthatreportedbydifferent authors ofother partsof theworld. Cameron²³ estimated a low prevalence of refractiveerror related headache in a sample of 50 patients referred for ocular examination and Jain et al.²⁴ in an observational study conducted in India reported only 1.48% (of 202 patients)prevalence of refractiveerrorsinheadachepatients.Thesediscrepancies arefromthepatientenrolment.Theyhaveincludedevery patient of headache without speciality consultation. We observed28.75%patientswithheadachetohavepoorbinoc- ularityofwhich16.25%(outof80non-presbyopicpatients) had receded Near Point of Convergence. This prevalence of convergence insufficiency is less than that of Gupta etal.²⁵ in India (49%),Romania²⁶ (60.4%) andPatwardhan and Sharma²⁷ (71.4%) in India. These discrepancies might be because of the different working environments of the patients. Gordon¹⁵ also cites poor binocular status as a potentialsourceofheadache.The literaturealsoprovides anecdotalsupportforthehypothesisthatcertainoptomet- ricanomalies,especiallydecompensatedexophoria,maybe prevalentin headache.²⁸ Alarge number of patientswith BSV anomalies in our study might be correlated to these observations.AlthoughthesedataimplythatNepalesepeo- plefromruralareashavemoreocularproblemsleadingto headache,thedifferingprevalenceofthesemorbiditiesin differentcountriesmustbeaccountedforeconomical and

psychological well being because these people might be exaggeratingtheirheadachesymptoms.Moreover,thesedis- crepanciescouldbebecauseofthepatientenrolmentbeing veryselectiveinourstudywhereallthenonocularcauses ofheadachewereexcluded.Thehigherproportionofpeo- plewithpreviouseyeexaminationinthisstudysuggeststhat thesepeoplethinkthattheireyesareculpritbehindtheir headache.Ourobservationsfortheprevalenceofheadache inuncorrectedrefractiveerrorsareinaccordancewiththat ofGil-GouveiaandMartins.¹⁴

This study provides further evidence that headache is morecommon infemale (p>0.001)similarto observation noted by Hendricks et al.²⁹ We observed that every six patients out of ten have headache in the non-presbyopic adultgroupwithfemaleshavingmorethantwofold(2.33 fold) prevalence over male. Headache prevalence in this particularagegroupmightbebecauseofthepsychological stress caused by educational pressures for career devel- opment, emotional factors and family conflicts. Female preponderancecouldbebecauseoftheculturally setfac- torsandtheeffectsofmaledominatedsocietywhichmay leadtopsychologicalstress.³⁰Prevalencerateofheadache has been observed to increase at the age of 13, particu- larlyamonggirlsbecauseofpuberty.⁴Inourstudy,patients in theschoolage comprisedof 20%.Headache inthisage group could bebecause of home and school environment whichputspressureforbetterperformanceinthestudies.

Someauthorsbelievethatspectaclesforthecorrection oflowdegreeofrefractiveerrorsisjustaplacebo¹⁵ while others claim it to be an effective method to ameliorate headache symptoms.²⁹ Our results also suggest the claim that low degrees of refractive errorsare associated with headachebecause88%ofthesepatientshadbeenpresent- ingvisualacuityof6/6and6/9.Onehypothesisstatesthat even the minor degree of astigmatic errors of refraction causes changes tovisual perception that alter the hyper- excitability in the visual cortex of the brain of headache sufferers.³⁰ Astigmaticblurmayexacerbatetheperception ofstripedpatternswhicharethoughttobeimportantinthe visual triggers of different types of headaches.³¹ Another hypothesis couldbe the neurotic personality traits which meanthatthepatientswithheadachedemandlowdegrees ofrefractiveerrorcorrection.^32,33Itispossiblethatrefrac- tiveerrorcouldhaveanassociationwithheadachehavingno impactontheseveritybuttheuncorrectedrefractiveerror exacerbates the headache symptoms.² We have observed that theprevalence of astigmatism is higher than thatof hyperopiaandmyopia(63.63%,27.27%and9.09%).Ourstudy is in an agreement withthat of Patwardhan and Sharma whoclaimthesametrendinrefractiveerrorprevalencein headachepatients.²⁷

The prevalence of computer vision syndromeobserved in our study (13%) is similar (9---12%) to that of the United States.²⁸ The patho-physiology of headache asso- ciated with prolonged VDU use resides within the ocular surface abnormalities, accommodative spasms, dry eyes and/orextra-ocularetiologies.³⁴

Thefirstlimitationofourstudyisthatourpatientswere recruitedfromahospitaloutpatientclinicpopulationwith asmallsamplesize,sotheseresultsmaynotberepresen- tativeofthegeneralpopulationasawhole.Second,wedid notperformvisualfieldtestingasallthepatientswerefirst

examinedbydifferentcategoryofmedicalspecialistswhich examineheadachepatientsandallthepossiblenonocular causeswereruledout.Visualfieldtestinghasacorerolein thedifferentiationofocularandnonocularheadachewhich needstobeincluded amongthewiderangeofophthalmic tests.Third, the inadequatepatient masking is the prob- ablereasontorevealhigh prevalenceofocular morbidity.

Ourstrongpointistheveryselectivepatientenrolment.We haveexcludedeveryheadachewithknownetiology.

Inconclusion,thisstudyprovidestheevidencethatocu- lar morbidities and headache symptoms are linked very frequently.Thoroughrefractiveevaluationandbinocularity evaluationareimportantinheadache.Itisimportanttoget agoodheadachehistorysothatpatientcanbereferredto theappropriatespecialistforthemanagementofheadache andhenceliveabetterqualityoflife.

Conflicts of interests

None.

Acknowledgments

We would liketo acknowledge Asst. Prof Dr Pankaj Pant;

MD(General Medicine),Dr Bikash Shrestha; MD(ENT) and DrAjayRisal;MD(Psychiatry)forhelpingusinco-managing thepatients.WewouldliketoacknowledgeMrRoshanKumar Mahato;BachelorinPublicHealth,forhelpinguswithsta- tisticalanalysis.

References

1.OlesenJ,BesA,KunkelR,etal.Theinternationalclassification ofheadachedisorders. 2nded.HeadacheClassificationSub- committeeoftheInternational HeadacheSociety:Blackwell Publishing.Cephalalgia2004;24:150.

2.Harle DE, Evans BJW. The correlation between migraine headacheandrefractiveerrors.OptomVisSci.2006;83:82---87.

3.ShahR,EdgarDF,RabbettsR,etal.Thecontentofoptometric eyeexaminationsforayoungmyopewithheadaches.Ophthal PhysiolOpt.2008;28:404---421.

4.AlawnehHF,BatainehHA.Prevalenceofheadacheandmigraine among school children in Jordan. Sudan J Public Health.

2006;1:289---292.

5.TorelliP,AbrignaniG,BerzieriL,etal.Population-basedpace study:lifetimeandpast-yearprevalenceofheadacheinadults.

NeurolSci.2010;31:145---147.

6.KrystS,ScherlE.Apopulation-basedsurveyofthesocialand personalimpactofheadache.Headache.1994;34:344---350.

7.RasmussenBK,JensenR,SchrollM,OlesenJ.Epidemiologyof headacheinageneralpopulation----aprevalencestudy.JClin Epidemiol.1991;44:1147---1157.

8.O’Brien B, Goeree R, Streiner D. Prevalence of migraine headache in Canada: a population-based survey. Int J Epi- demiol.1994;23:1020---1026.

9.ThomasE,BoardmanHF,OgdenH,MillsonDS,CroftPR.Advice andcareforheadaches:whoseeksit,whogivesit?Cephalal- gia.2004;24:740---752.

10. NishimotoY,SuzukiS,UtsugisawaK,etal.AutoimmuneDis.

2011,840364[Epub2011Jul28].

11. DaroffRB.Ocularcausesofheadache.Headache.1998;38:661.

12.American Optometric Association. Careof the patientwith accommodativeandvergencedysfunction.Optometricclinical practiceguideline;2010.

13.Bellows JG. Headache and the eye. Headache. 1968;7:

165---170.

14.Gil-GouveiaR,MartinsIP.Headachesassociatedwithrefractive errors:mythorreality?Headache.2002;42:256---262.

15.Gordon GE, Chronicle EP, Rolan P. Why do we still not knowwhether refractiveerrorcausesheadaches? Towardsa frameworkforevidencebasedpractice.OphthalPhysiolOpt.

2001;21:45---50.

16. WhittingtonTD.Theartofclinicalrefraction.London:Oxford UniversityPress;1958.

17. Sheard C. Zones of ocular comfort. Am J Optom. 1930;7:

9---25.

18.GordonDM. Someheadachesin anophthalmologist’s office.

Headache.1966;6:141---146.

19.EckardtLB, McLeanJM,Goodell H.Experimental studieson headache:thegenesisofpainfrom theeye. ProcAssocRes NervMentDis.1943;23:209---227.

20.http://www.dhulikhelhospital.org/index.php/about-us.

21.BlauJN.Howto takeahistory ofheadorfacialpain.BMJ.

1982;285:1249---1251.

22.MurdochIE,MorrisSS,CousensSN.Peopleandeyes:statisti- calapproachesinophthalmology.BrJOphthalmol.1998;82:

971---973.

23. CameronME.Headachesinrelationtotheeyes.MedJAust.

1976;1:292---294.

24.JainAP,ChauhanB, BhatAD.Sociodemographicandclinical profileofheadache---aruralhospital-basedstudy.IndianAcad ClinMed.2007;8:26---28.

25.GuptaA,KailwooSK,Vijayawali.Convergenceinsufficiencyin patientsvisitingeyeopdwithheadache.JKScience.2008;10:

3.

26.DragomirM,TrusL,ChirilaD,StinguC.Orthoptictreatment efficiencyinconvergenceinsufficiencytreatment.Oftalmolo- gia.2001;53:66---69.

27. PatwardhanSD, SharmaP,SaxenaR,KhandujaSK.Preferred clinicalpracticeinconvergenceinsufficiencyinIndia:asurvey.

IndJOphthalmol.2008;56:303---306.

28.DaumKM,GoodG,TijerinaL.Symptomsinvideodisplayter- minaloperatorsandthepresenceofsmallrefractiveerrors.J AmOptomAssoc.1988;59:691---697.

29.HendricksTJW,DeBrabandarJ,HorstFVD,HendrikseF,Knot- tnerus AJ. Relationship between habitual refractive errors andheadache complaintsin schoolchildren. OptomVisSci.

2007;84:137---143.

30.BreslauN, AndreskiP.Migraine,personality, and psychiatric comorbidity.Headache.1995;35:382---386.

31.WilkinsA,Nimmo-SmithI,TaitA,etal.Aneurologicalbasisfor visualdiscomfort.Brain.1984;107:989---1017.

32.WilkinsAJ.Visualstress.Oxford:OxfordUniversityPress;1995.

33.WelchKM.Contemporaryconceptsofmigrainepathogenesis.

Neurology.2003;61:2---8.

34. BlehmC,VishnuS,KhattakA,MitraS,YeeRW.Computervision syndrome:areview.SurvOphthalmol.2005;50:253---262.