THYROID EYE DISEASE

THYROID+EYE+DISEASE%0d%0aAutoimmune+disorder+characterised+by+infiltrative+orbitopathy%0d%0a%0d%0a%0cGraves'+disease%0d%0a%ef%82%ae%0d%0a%0d%0aGraves'+disease+is+the+most+common+thyroid+abnormality+associated+with+thyroid+orbitopathy%2c+but+other+disorders+of+the+thyroid+can+have+similar+ocular+manifestations.+These+include+Hashimoto's+thyroiditis%2c+thyroid+carcinoma%2c+primary+hyperthyroidism%2c+and+neck+irradiation.+%ef%82%ae+Approximately+40%25+of+patients+with+Graves'+disease+have+or+will+develop+thyroid+orbitopathy.%0d%0a%0d%0a%0cTHYROID+EYE+DISEASE%0d%0a%ef%82%ae+Associated%0d%0a%0d%0awith+normal+to+abnormal+thyroid+function+which+may+coexist%2c+precede+or+follow+the+orbitopathy.+%ef%82%ae+Related+to+but+not+the+same+as+Graves+Ophthalmopathy+(GO)+The+natural+history+was+described+by+Rundle+and+Wilson+in+1945%0d%0a%0d%0a%0cThyroid+status%ef%82%ae%0d%0a%0d%0aOf+those+patients+with+thyroid+orbitopathy%2c+approximately+80%25+are+clinically+hyperthyroid+and+20%25+are+clinically+euthyroid.4+Most+patients+with+euthyroid+Graves'+orbitopathy%2c+however%2c+have+some+detectable+laboratory+evidence+of+subclinical+hyperthyroidism.+%ef%82%ae+Both+hyperthyroid+and+euthyroid+patients+can+develop+clinical+signs+and+symptoms+of+thyroid+orbitopathy.+In+general%2c+patients+with+euthyroid+Graves'+disease+tend+to+have+less+severe+orbitopathy%0d%0a%0d%0a%0cTHYROID+EYE+DISEASE%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aThe+goal+is+to+identify+and+treat+patients+who+are+at+particular+risk+of+sight+threatening+complications.+The+disease+has+a+finite+period+of+activity+until+it+becomes+burnt+out.The+yellow+region+shows+the+early+phase+where+there+is+the+best+response+to+treatment.+Type+1+younger+age+group%2c+whiter+eyes+with+proptosis.+Inflammation+is+mostly+in+orbital+fat+not+muscles.+Type+11+older+patient+with+red+eyes%2c+severe+sight+threatening+disease%2c+tobacco+addiction+is+frequent.%0d%0a%0d%0a%0cGeneral+Considerations%0d%0a%ef%82%ae%0d%0a%0d%0aSevere+exophthalmos+and+compressive+optic+neuropathy+are+slightly+more+common+in+older+men.+%ef%82%ae+There+appears+to+be+an+increased+prevalence+of+thyroid+disease+in+smokers%2c+for+whom+the+relative+risk+of+developing+Graves'+orbitopathy+is+twice+as+high+as+it+is+for+nonsmokers.+%ef%82%ae+The+reason+for+this+difference+is+not+known%2c+but+one+possibility+is+that+the+decreased+immunosuppression+in+smokers+may+allow+greater+expression+of+autoimmune+processes.%0d%0a%0d%0a%0cPATHOGENESIS%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aType+II+reaction%3a-+autoimmune+antibodies+target+somatic+tissues+such+as+extraocular+muscles+causing+an+antigen-antibody+reaction.+A+large+number+of+lymphokines+are+implicated+in+the+inflammatory+process.+Inflammation+results+in+production+of+mucopolysaccharides+by+fibroblasts+leading+to+swelling+followed+by+collagen+production+resulting+in+restriction.+There+is+a+high+concentration+of+macrophages+in+the+inferior+rectus+muscle+as+well+as+CD4%2b+memory+T+cells+and+CD8+T+cells.+This+may+account+for+the+clinical+observation+of+maximal+disease+activity+in+this+muscle.%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0a%0cETIOLOGY%0d%0a%ef%82%ae%0d%0a%0d%0aIn+1956%2c+Adams+and+Purves+isolated+a+factor+in+the+serum+of+patients+with+Graves'+hyperthyroidism+that+caused+stimulation+of+the+animal+thyroid+gland.+This+factor+was+very+similar+to+TSH+but+had+a+longer+half-life.+It+was+therefore+called+long-acting+thyroid+stimulator+(LATS).+In+1964%2c+Kriss+and+colleagues+showed+that+LATS+had+the+structure+of+an+IgG+immunoglobulin+and+its+action+could+be+neutralized+by+thyroid+tissue%2c+indicating+that+it+was+an+antibody.+Further+experiments+showed+that+the+antibody+was+directed+against+the+receptor+for+TSH+on+the+follicular+cell+of+the+thyroid+gland.%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0a%0cThyrotropin+receptor+antibodies+(TRAb).%0d%0a%ef%82%ae+antibodies%0d%0a%0d%0awere+originally+classified+into+those+with+stimulatory+properties+called+thyroid-stimulating+immunoglobulin+or+antibody+(TSI%2c+TSAb)+and+those+with+inhibitory+properties+called+TSH-binding+inhibiting+immunoglobulin+or+antibody+(TBII%2c+TBIA).+Both+of+these+groups+are+now+referred+to+as+thyrotropin+receptor+antibodies+(TRAb).%0d%0a%0d%0a%0cPHYSIOLOGY%0d%0a%ef%82%ae+Hypothalamus%0d%0a%0d%0aTRH+pituitary+TSH+thyroid+T3+and+T4+%ef%82%ae+85%25+of+T4+converted+to+T3+in+tissues.+%ef%82%ae+T3+has+5+times+the+activity+of+T4.%0d%0a%0d%0a%0cPathology%0d%0a%ef%82%ae%0d%0a%0d%0aThe+predominant+orbital+pathology+is+inflammation+of+the+orbital+soft+tissues+and+extraocular+muscles.+This+immune-mediated+inflammation+consists+mostly+of+lymphocytes+and+plasma+cells%2c+with+a+scattering+of+mast+cells.+These+inflammatory+changes+differ+from+the+more+exuberant+lymphocytic+infiltration+of+the+orbital+fat+and+muscles%2c+including+their+tendinous+insertions+seen+in+orbital+pseudotumor%0d%0a%0d%0a%0cPathology%0d%0a%ef%82%ae%0d%0a%0d%0aThe+earliest+change+in+extraocular+muscles+appears+to+be+inflammation+of+the+endomysial+connective+tissues%2c+which+stimulates+endomysial+fibroblasts+to+produce+first+hyaluronic+acid+and+then+collagen.+In+the+acute+stage+there+is+inflammation%2c+edema%2c+and+deposition+of+glycosaminoglycans.+Eventually+there+is+tethering+of+orbital+tissues+due+to+fibroblast+proliferation.%0d%0a%0d%0a%0cCLINICAL%0d%0a%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae%0d%0a%0d%0a(orbitopathy+in+general+is+worst+in+the+older+age+groups.)+LID+RETRACTION1.+sympathetic+overactivity2.+infiltration+of+levator+%2f+SR+complex3.+hypotropia+(retraction+disappears+on+downgaze)+SIGNS%3a-+Dalrymples+(lid+retraction)%2c+von+Graefe+(lid+lag)%2c+Kocher%c2%b4s+(staring+appearance)%0d%0a%0d%0aINFILTRATION+1.+soft+tissue+involvement+%3a-+chemosis%2c+conjunctival+injection+over+the+recti+insertions%2c+puffy+lids%0d%0a%0d%0aSuperior+limbic+keratoconjunctivitis+(SLK)+due+to+redundant+conjunctiva%0d%0a%0d%0a%ef%82%ae%0d%0a%ef%82%ae+%ef%82%ae+%ef%82%ae+%ef%82%ae%0d%0a%0d%0a2.+muscle+involvement+%3a-+diplopia+due+to+restriction.+Order+of+involvement+IR%2c+MR%2c+SR+(LR)+Braley%c2%b4s+sign+%3d+increased+IOP+on+upgaze+(%3e4mmHg)+3.+proptosis+%3a-+TED+is+the+commonest+cause+of+unilateral+or+bilateral+proptosis%0d%0a%0d%0a%0cSight+Threatening+Complications%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae+%ef%82%ae+%ef%82%ae%0d%0a%0d%0aoptic+nerve+compression+%3a-+%3c5%25+affected%2c+due+to+compression+of+orbital+apex+by+enlarged+EOM.+Look+for+decreased+VA%2c+colour+vision+defects%2c+arcuate+or+central+scotomata%2c+swollen+optic+disc.+Confirmation+by+orbital+CT.+Treatment+by+medical+or+surgical+decompression.+corneal+exposure%3a-+potentially+serious%3a-+treat+with+lubricants%2c+lid+taping%2c+tarsorrhaphy%2c+decompression+less+common+causes+of+visual+loss%3a-+glaucoma%2c+vascular+compression%0d%0a%0d%0a%0cCorneal+involvement%0d%0a%ef%82%ae%0d%0a%0d%0aCorneal+involvement+due+to+exposure+keratitis+may+result+from+proptosis%2c+upper+eyelid+retraction%2c+lower+eyelid+retraction%2c+lagophthalmos%2c+or+a+combination+of+these.+A+primary+lacrimal+gland+dysfunction+may+also+be+present+in+Graves'+orbitopathy.+Although+still+speculative%2c+there+is+some+evidence+of+a+change+in+the+protein+composition+of+tears+in+patients+with+thyroid+orbitopathy.+This+change+might+be+caused+by+an+altered+rate+of+tear+production+or+by+a+general+change+in+tear+composition%0d%0a%0d%0a%0cCLINICAL+ASSESSMENT%0d%0a%ef%82%ae%0d%0a%0d%0aMOURITS+CLASSIFICATION+Indicates+position+on+Rundles+curve+(the+score+reduces+as+inflammation+decreases).Parameters+of+disease+activity%3a+Integrated+severity+score+of+Graves+ophthalmopathy+(GO).Oppressive+feelingPain+on+deviation+from+primary+positn%2c+redness+of+lids+(ie.+recent+inflammation)%2c+diffuse+redness+of+conjunctiva%2c+chemosis%2c+swollen+caruncle%2c+oedema+of+eyelids%2c+Proptosis+(increase+of+2mm+or+more)....%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aWERNER%c2%b4S+CLASSIFICATION+Indicates+the+damage+level+(so+the+score+may+not+reverse+as+activity+diminishes).0+Nil+(no+symptoms+or+signs).1+Only+signs+of%3a+a)+stare+b)+lid+lag%2c2.+Soft+tissue+involvement%3a+0)+absent+a)+minimal+b)+moderate+c)+marked.3+Proptosis+of+3mm+or+more%3a+0)+absent+a)+3-4+mm+b)+5-7+mm+c)+8+or+more+mm.4+Diplopia%3a+0)+absent+a)+limitation+at+extremes+of+gaze+b)+evident+restriction+of+motion+c)+fixation+of+globe.5+Corneal+involvement%3a+0)+absent+a)+SPE+b)+corneal+ulceration%2c+c)+necrosis+or+perforation.6+Sight+loss+(due+to+optic+nerve)%3a%0d%0a0)+absent+a)+20%2f20-20%2f60+b)20%2f70-20%2f200+c)Worse+than+20%2f200.%0d%0a%0d%0a%0cTHYROID+EYE+DISEASE%0d%0a%ef%82%ae%0d%0a%0d%0aLID+RETRACTION1.+sympathetic+overactivity+infiltration+of+levator+%2f+SR+complex.+hypotropia+(retraction+disappears+on+downgaze)+%ef%82%ae+SIGNS%3a-+Dalrymples+(lid+retraction)%2c+von+Graefe+(lid+lag)%2c+Kocher%c2%b4s+(staring+appearance)%0d%0a%0d%0a%0cTHYROID+EYE+DISEASE%0d%0a%ef%82%ae%0d%0a%0d%0aINFILTRATION+%ef%82%ae+1.+soft+tissue+involvement+%3achemosis%2c+conjunctival+injection+over+the+recti+insertions%2c+puffy+lids%0d%0a%0d%0a%0cTHYROID+EYE+DISEASE%0d%0a%ef%82%ae%0d%0a%0d%0aSuperior+limbic+keratoconjunctivitis+(SLK)%0d%0a%0d%0a%0cOptic+neuropathy+with+visual+loss%0d%0a%ef%82%ae+%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aThe+prevalence+of+optic+neuropathy+with+visual+loss+in+patients+with+thyroid+orbitopathy+is+less+than+5%25.+Optic+neuropathy+is%2c+however%2c+the+most+common+cause+of+blindness+secondary+to+thyroid+orbitopathy.+Its+onset+is+often+insidious+and+may+be+masked+by+other+symptoms.+These+patients+are+usually+older+(age+50+to+70)+are+more+frequently+male%2c+have+a+later+onset+of+thyroid+disease%2c+and+more+often+have+diabetes.+Optic+neuropathy+is+usually+bilateral%2c+but+up+to+one+third+of+cases+may+be+unilateral.%0d%0a%0d%0a%0cOptic+neuropathy%0d%0a%ef%82%ae%0d%0a%0d%0aAlthough+a+history+of+decreased+vision+should+be+carefully+sought%2c+it+is+important+to+realize+that+optic+neuropathy+can+occur+in+a+significant+number+(18%25)+of+patients+with+visual+acuities+in+the+range+of+20%2f20+to+20%2f25+(6%2f6+to+6%2f7.5).*An+afferent+pupillary+defect+is+present+in+35%25.+An+abnormal+disc+(either+swollen+or+pale)+is+seen+in+only+52%25.+Visual+field+defects+are+present+in+66%25.Other+tests+that+can+be+useful+include+color+vision+testing+and+visual+evoked+potentials+(VEPs).+The+Farnsworth-Munsell+100-hue+test+is+a+sensitive+indicator+of+optic+nerve+dysfunction%2c+but+pseudoisochromatic+screening+procedures+(e.g.%2cIshihara+plates)+rarely+identify+an+acquired+color+defect+unless+optic+neuropathy+is+severe.The+pattern+reversal+VEP+is+very+sensitive+at+detecting+early+optic+neuropathy+and+may+be+a+useful+means+of+following+patients+after+treatment.%0d%0a%0d%0a%0cIntraocular+pressure%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aThe+increased+intraocular+pressure+measured+during+upgaze+in+patients+with+thyroid+orbitopathy+has+been+a+controversial+finding.+When+restriction+of+the+inferior+rectus+muscle+occurs%2c+the+intraocular+pressure+may+increase+by+6+mm+Hg+or+more+in+upgaze+as+compared+with+primary+gaze.+The+increased+intraocular+pressure+in+upgaze+is+a+normal+phenomenon+exaggerated+by+thyroid+orbitopathy+In+patients+with+severe+infiltrative+disease+there+is+an+increased+pressure+on+upgaze+as+compared+with+normal+controls+and+patients+with+mild+disease.+It+is+often+not+an+indicator+of+early+disease+because+it+occurs+infrequently+in+patients+with+minimal+eye+findings%0d%0a%0d%0a%0cINVESTIGATION%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aSEROLOGICALT3+(hyperthyroid)T4+TSH+(hypothyroid)TSI+(thyroid+stimulating+immunoglobulin).+RADIOLOGICAL+TESTSOrbital+CT+(enlarged+muscle+belly%2c+tendon+normal).+Coca-Cola+bottle+sign+%3d+muscle+swelling+deforming+ethmoidal+bones.MRI+T2+showing+oedema+of+muscles%3b+repeating+the+scan+in+different+positions+of+gaze+can+create+a+pseudo-video+of+eye+movements+(for+assessment+of+muscle+restriction).+RADIOISOTOPE+TESTS+Octreoscan%3a+quantitative+uptake+of+radio-labelled+octreotide+(which+is+a+somatostatin+analogue).%0d%0a%0d%0a%0cVISUAL+FIELD%0d%0a%ef%82%ae%0d%0a%0d%0aA+visual+field+should+be+performed+in+all+patients+suspected+to+have+optic+neuropathy+and+is+useful+when+following+patients+after+initiation+of+treatment.+Characteristically%2c+a+central+scotoma+or+an+inferior+altitudinal+defect+is+seen+in+cases+of+compressive+optic+neuropathy.+Other+visual+field+defects+include+an+enlarged+blind+spot%2c+paracentral+scotoma%2c+nerve+fiber+bundle+defect%2c+or+generalized+constriction.%0d%0a%0d%0a%0cULTRASONOGRAPHY%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aUltrasonography+can+be+useful+to+detect+early+thyroid+disease+in+patients+with+equivocal+laboratory+tests.+Most+patients+with+Graves'+disease%2c+even+those+without+overt+eye+findings%2c+have+ultrasonographic+evidence+of+extraocular+muscle+involvement.46+Ultrasonography+is+believed+by+some+to+be+more+accurate+than+CT+in+detecting+enlargement+of+the+extraocular+muscles.+Also%2c+visualization+of+the+tendinous+insertions+onto+the+globe+may+be+more+accurately+assessed+using+ultrasonography+when+differentiating+enlarged+extraocular+muscles+secondary+to+myositis+from+hyperthyroid+orbitopathy.+Ultrasonography+is%2c+however%2c+less+suited+than+CT+to+assessing+muscle+thickness+at+the+orbital+apex.+This+test+may+also+be+helpful+in+distinguishing+between+active+and+inactive+disease.+Examination+of+the+extraocular+muscles+shows+that+there+is+a+lower+internal+reflectivity+in+active+as+compared+with+inactive+disease.%0d%0a%0d%0a%0cCT+findings+in+thyroid+orbitopathy%0d%0a%ef%82%ae%0d%0a%0d%0aThe+most+characteristic+CT+finding+in+thyroid+orbitopathy+is+enlargement+of+the+extraocular+muscles+with+normal+tendinous+insertions+onto+the+globe.+Other+findings+include+proptosis+and+anterior+prolapse+of+the+orbital+septum+due+to+excessive+orbital+fat+and+muscle+swelling+(see+Fig.+4).Patients+at+risk+for+developing+optic+neuropathy+may+also+have+severe+apical+crowding%2c+a+dilated+superior+ophthalmic+vein%2c+and+anterior+displacement+of+the+lacrimal+gland.+Of+these%2c+apical+crowding+is+the+most+sensitive+indicator+for+the+presence+of+optic+neuropathy+The+CT+scan+should+be+done+in+the+coronal+plane+to+assess+the+enlargement+of+the+extraocular+muscles+at+the+apex+because+axial+sections+can+sometimes+be+misleading.%0d%0a%0d%0a%0cTHYROID+EYE+DISEASE%0d%0a%ef%82%ae%0d%0a%0d%0aOrbital+CT+(enlarged+muscle+belly%2c+tendon+normal)%0d%0a%0d%0a%0cMAGNETIC+RESONANCE+IMAGING%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aMRI+using+1.5+tesla+units+and+orbital+surface+coils+provides+optimal+spatial+resolution+of+the+orbit.34+MRI+may+also+be+useful+in+distinguishing+between+active+and+inactive+disease.+The+changing+intensities+between+T1-+and+T2-weighted+images+may+differentiate+the+active+edematous+from+the+inactive+fibrotic+muscle+changes.+Extraocular+muscles+that+have+acute+inflammation+have+longer+T2+times+owing+to+the+higher+water+content.+Because+acute+inflammatory+disease+responds+better+to+radiation+therapy+than+chronic+fibrosis%2c+the+information+gained+from+MRI+may+theoretically+be+helpful+in+choosing+patients+for+radiation+therapy.%0d%0a%0d%0a%0cSYSTEMIC+THYROID+DISEASE%0d%0a%ef%82%ae%0d%0a%0d%0aThere+are+no+good+recent+studies+of+the+natural+history+of+untreated+hyperthyroidism%2c+but+based+on+older+reports%2c+Wilson56+determined+that+about+one+third+of+patients+spontaneously+improve%2c+one+third+remain+chronically+hyperthyroid%2c+and+one+third+progress+to+thyroid+storm+and+occasionally+death.+Because+it+is+not+possible+to+predict+which+patients+will+spontaneously+improve%2c+treatment+of+thyroid+dysfunction+is+recommended.%0d%0a%0d%0a%0cTreatment%0d%0a%ef%82%ae+acute%0d%0a%0d%0acongestive+ophthalmopathy%2c+%ef%82%ae+compressive+optic+neuropathy%2c+%ef%82%ae+motility+disorders%2c+%ef%82%ae+eyelid+abnormalities.%0d%0a%0d%0a%0cTREATMENT+Acute+Congestive+Orbitopathy%0d%0a%ef%82%ae%0d%0a%0d%0a1.+SYMPTOMATIC%3a-+elevate+bedhead%2c+lubricants%2c+lid+taping%2c+diuretics+2.+SYSTEMIC%3aa)+Normalise+thyroid+function+with+or+without+thyroxine.%0d%0a%0d%0a%ef%82%ae+%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aPatients+rendered+euthyroid+do+improve+their+GO+score%0d%0a%0d%0aTallstedt+trial+N+Eng+J+Med+1992+antithyroid+drugs+cause+a+10%25+chance+of+new+or+worsening+GO+but+radio-iodine+causes+a+30%25+chance+of+new+or+worsening+GO.%0d%0a%ef%82%ae%0d%0a%0d%0a%0cCorticosteroids+have+been+used+successfully+in+the+treatment+of+acute+congestive+orbitopathy%0d%0a%ef%82%ae%0d%0a%0d%0aCorticosteroids+have+been+used+successfully+in+the+treatment+of+acute+congestive+orbitopathy.+They+are+believed+to+work+by+altering+cell-mediated+immune+response+and+diminishing+the+production+of+mucopolysaccharides+by+the+orbital+fibroblasts.Corticosteroids+result+in+improvement+of+soft+tissue+involvement+and+compressive+optic+neuropathy+(but+do+not+have+as+much+of+an+effect+on+diplopia+Traditionally%2c+a+%22short+burst%22+of+high-dose+corticosteroids+has+been+given%2c+usually+in+the+range+of+60+to+120+mg%2fday+of+oral+prednisone.+Improvement+in+subjective+symptoms+such+as+pain+and+tearing+usually+occurs+first%2c+often+as+early+as+24+to+48+hours%2c+followed+by+improvement+in+soft+tissue+congestion+and+muscle+function+over+a+period+of+days+to+weeks.%0d%0a%0d%0a%0cSteroid+Therapy%0d%0a%ef%82%ae+Prednisone+or+prednisolone%0d%0a%ef%82%ae%0d%0a%0d%0aThis+is+standard+treatment+but+there+are+frequent+side+effects.+No+response+in+35%25+of+patients+and+anyway+the+response+is+only+partial.+High+dose+steroids+given+early+in+the+disease+when+muscle+swelling+occurs+does+not+necessarily+limit+the+long+term+course+of+the+disease.+If+there+is+no+response+to+high+dose+steroids+in+the+first+three+weeks+they+should+be+rapidly+reduced.+Prednisolone+%2b+orbital+radiotherapy+has+slightly+more+effect+than+either+alone.Use+high+dose+pulsed+methylprednisolone+if+urgent+optic+nerve+decompression+is+required%2c+This+is+more+effective+than+oral+treatment+but+it+is+expensive+and+not+justified+in+most+cases+of+TED.%0d%0a%0d%0a%0cRadiation+therapy%0d%0a%ef%82%ae%0d%0a%0d%0aDuring+the+past+few+years%2c+radiation+therapy+has+reemerged+as+a+useful+form+of+treatment+of+severe+orbitopathy.+The+rationale+for+the+use+of+radiation+therapy+is+reduction+or+elimination+of+the+pathogenic+orbital+lymphocytes%2c+which+are+markedly+radiosensitive.+It+is+also+thought+that+the+glycosaminoglycan+production+by+fibroblasts+is+reduced%2c+thereby+reducing+orbital+edema%2c+orbital+tension%2c+and+conjunctival+injection.+Although+congestive+findings+improve+most+consistently%2c+significant+improvement+in+proptosis+and+extraocular+muscle+function+has+been+reported.Like+corticosteroids%2c+radiation+therapy+is+most+effective+within+the+first+year%2c+when+significant+fibrotic+changes+have+not+yet+occurred.+Mourits+and+associates%2c135+however%2c+suggest+that+periods+of+active+orbital+inflammation+within+the+long+natural+history+of+thyroid+orbitopathy+would+benefit+from+corticosteroids+or+radiation+therapy.%0d%0a%0d%0a%0cRadiotherapy%0d%0a%ef%82%ae%0d%0a%0d%0aRETROBULBAR+RADIOTHERAPY%3a-+Trial+of+prednisone+versus+radiotherapy+showed+no+difference+in+clinical+improvement+(about+50%25).The+patients+all+tolerated+retrobulbar+radiotherapy+better+than+steroids+Consider+if+steroid+maintenance+%3e+25mg%2f+day.+Best+effect+in+acute+disease.Do+not+irradiate+patients+with+diabetes+mellitus+as+they+are+more+susceptible+to+radiation+retinopathy.2000rads%2f+10days%2c+effect+starts+at+4+weeks%2c+maximal+4+months.%0d%0a%0d%0a%0cCompressive+Optic+Neuropathy%0d%0a%ef%82%ae%0d%0a%0d%0aCompressive+optic+neuropathy+can+cause+permanent+visual+loss.+The+treatment+possibilities+include+high+doses+of+corticosteroids%2c+irradiation%2c+and+orbital+decompression.+Some+patients+require+only+one+of+these+modalities%2c+while+other+patients+need+combined+therapies.%0d%0a%0d%0a%0cCompressive+Optic+Neuropathy%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aAs+in+the+treatment+of+acute+congestive+thyroid+orbitopathy%2c+radiation+therapy+is+becoming+increasingly+popular.+A+retrospective+series+of+84+patients+with+compressive+optic+neuropathy+treated+with+either+corticosteroids+or+radiation+therapy+supports+mounting+evidence+that+radiation+therapy+may+be+safer+and+more+effective+than+corticosteroids.+Radiation+therapy%2c+however%2c+must+be+administered+in+fractionated+doses%2c+which+delays+its+beneficial+effect.+For+this+reason%2c+if+visual+dysfunction+progresses+while+the+patient+is+on+corticosteroids%2c+surgical+decompression+is+usually+recommended+if+the+patient+is+a+surgical+candidate.%0d%0a%0d%0a%0cOrbital+decompression%0d%0a%ef%82%ae%0d%0a%0d%0aOrbital+decompression+is+indicated+for+compressive+optic+neuropathy+when+there+has+been+failure+of+or+contraindication+for+corticosteroids+or+radiation+therapy+or+if+corticosteroid+dependence+has+developed+with+intolerable+side+effects.+Other+indications+include+excessive+proptosis+with+exposure+keratitis+and+corneal+ulceration%2c+pain+relief%2c+and+cosmesis+for+disfiguring+exophthalmos.+Orbital+decompression+may+also+be+indicated+as+a+preliminary+procedure+to+extraocular+muscle+surgery+on+a+patient+with+sufficient+proptosis+to+suggest+that+decompression+might+ultimately+be+required.%0d%0a%0d%0a%0cOrbital+decompression%0d%0a%ef%82%ae%0d%0a%0d%0aA+variety+of+approaches+may+be+used%2c+each+with+its+own+advantages+and+associated+complications.+%ef%82%ae+The+transorbital+(via+fornix+or+eyelid)+approach+to+inferior+and+medial+wall+decompression+is+the+most+common+approach+used+by+ophthalmologists.+The+addition+of+a+lateral+wall+advancement+has+the+advantage+of+both+further+increasing+the+orbital+volume+and+simultaneously+improving+upper+eyelid+retraction%3b+this+is+the+technique+we+prefer.%0d%0a%0d%0a%0cORBITAL+DECOMPRESSION%0d%0a%ef%82%ae%0d%0a%0d%0aSubciliary+approach.Inferior+%26+medial+wall+(6mm+proptosis).Remove+bone+to+posterior+wall+maxillary+sinus+(5mm+more+posterior+on+medial+wall)%2c+Avoid+IO+neurovascular+bundle%2c+and+the+anterior+and+posterior+ethmoidal+arteries.Incise+periosteum+in+A-P+direction+posteriorly+and+circumferentially+anteriorly.+%ef%82%ae+Complications%3a+%ef%82%ae+visual+loss%2c+%ef%82%ae+A+pattern+ET%0d%0a%0d%0a%0cMotility+Disorders%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae%0d%0a%0d%0aA+major+source+of+morbidity+in+thyroid+orbitopathy%2c+and+the+most+frequent+problem+associated+with+orbital+decompression+surgery%2c+has+been+strabismus.+In+patients+with+relatively+minimal+degrees+of+ocular+misalignment%2c+diplopia+can+be+avoided+with+a+compensatory+head+posture%2c+Fresnel+plastic+press-on+prisms%2c+or+temporary+occlusion.+Unfortunately+there+is+significant+image+degradation+as+larger+prisms+are+used%2c+limiting+their+efficacy.+If+there+is+marked+asymmetry+in+ocular+deviation+in+different+fields+of+gaze%2c+prisms+are+also+less+effective.+In+some+cases+during+the+inflammatory+period%2c+use+of+intramuscular+botulinum+toxin+has+shown+some+efficacy.+Extraocular+muscle+surgery+should+be+postponed+until+the+muscles+are+no+longer+inflamed+and+the+deviation+has+remained+stable+for+at+least+6+months.%0d%0a%0d%0a%0cSurgery%0d%0a%ef%82%ae%0d%0a%0d%0aSTRABISMUS+SURGERY%3a-Aim+for+maximal+area+of+fusion+without+abnormal+head+posture.IR+recession+on+adjustable+%2b%2f-+contra+SR+recession+iii)+EYELID+SURGERY%3a%ef%82%ae%0d%0a%0d%0aUpper+Lid+retraction+-+Muller%c2%b4s+tenotomy+(%3c2mm)%2c+levator+Z+myotomy+or+recession+on+hangback+sutures%2c+levator+tenotomy+%2b%2f-+horns.+%ef%82%ae+Lower+Lid+retraction+-+Usually+needs+a+spacer+from+donor+sclera+(lid+retraction+X+2+%3d+amount+of+sclera+required)%0d%0a%ef%82%ae%0d%0a%0d%0aiv)+BLEPHAROPLASTY+for+excess+skin+and+fat+%ef%82%ae+Ideally+treatment+combines+a+multidisciplinary+coherent+approach+such+as+%ef%82%ae+Combined+radiotherapy+and+immunosuppression+trial%0d%0a%0d%0a%0cEyelid+Abnormalities%0d%0a%ef%82%ae%0d%0a%0d%0a%ef%82%ae+%ef%82%ae%0d%0a%0d%0aAs+with+other+thyroid+eye+problems%2c+eyelid+retraction+will+often+improve+with+time%2c+and+only+an+estimated+50%25+of+patients+with+eyelid+retraction+have+a+significant+eyelid+abnormality+5+years+later.+Eyelid+retraction+can+result+from+excessive+autonomic+discharge%2c+levator+fibrosis%2c+or+contraction+of+the+inferior+rectus+muscle.+Surgical+correction+of+eyelid+abnormalities+should+be+performed+only+after+orbital+or+extraocular+muscle+surgery+because+these+operations+may+change+eyelid+position.+For+example%2c+inferior+rectus+muscle+restriction+may+cause+upper+eyelid+retraction+because+of+the+superior+rectus%2flevator+palpebrae+superioris+overaction+against+the+restriction.+Specific+techniques+for+repair+of+eyelid+retraction+are+discussed+in+other+chapters.%0d%0a%0d%0a%0c