Ординатура / Офтальмология / Учебные материалы / Color Atlas of Ophthalmology The Quick-Reference Manual for Diagnosis and Treatment
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12 Strabismus 341
Differential Diagnosis
Sixth -n er ve palsy, fibrosis syn drom e, early accom m odat ive esot ropia, Duan e syn - drom e
Management
Bilateral m edial rect u s m u scle recession is th e in it ial u su al t reat m en t for in fan t ile esot ropia. Bilateral lateral rect us resect ion is used as a secon d procedu re for u n - dercorrect ion .
Accommodative Esotropia
Convergen t deviat ion of th e visu al axes is associated w ith act ivat ion of th e accom m odat ive reflex. Th e age of presen tat ion averages 30 m on th s, ranging from 6 m on th s to several years (Fig. 12.3).
A
Fig . 12.3 (A) Refractive esotropia. |
|
(B) High accommodative conver- |
|
gence esotropia. |
B |
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Presentation
Th ere is a m oderate angle of esot ropic deviat ion averaging 20 to 30 prism diop - ters. Th e con dit ion progresses from in term it ten t to con stan t esot ropia. Th e angle of deviat ion at n ear an d at dist an ce is u su ally sim ilar u n less th ere is a h igh accom - m odat ive convergen ce/accom m odat ion (AC/A) rat io w h ere th e n ear angle of devia- t ion is larger. Th e average hyperopic correct ion is +4.00 diopters. Accom m odat ive esot ropia is frequ en tly associated w ith am blyopia.
Types
Refract ive accom m odat ive esot ropia: High hyperopia an d n orm al accom m oda- t ive convergen ce/accom m odat ion . Th e angles of deviat ion at n ear an d at distan ce are sim ilar.
High accom m odat ive convergence/accom m odat ion esot ropia: Low hyperopia w ith a h igh accom m odat ive convergen ce/accom m odat ion . Th e angle of devia- t ion at n ear is larger th an th e dist an ce deviat ion .
Part ially accom m odat ive esot ropia: Com bin at ion of refract ive an d n on accom - m odat ive esot ropia. Hyperopic correct ion part ially corrects th e angle of devia- t ion . Associated w ith a delay in correct ion of th e accom m odat ive th ere is an accom m odat ive com pon en t .
Differential Diagnosis
Basic n on refract ive n on accom m odat ive esot ropia, in fan t ile esot ropia, acute eso- t ropia associated w ith n eu rological disorders, cyclic esot ropia, spasm of th e n ear syn kin et ic reflex, nyst agm us blockage syn drom e
Management
Man agem en t con sists of fu ll cycloplegic hyp eropic correct ion . Bifocals are prescribed for pat ien ts w ith h igh accom m odat ive convergen ce/accom m odat ion if th e eyes are st raigh t at distan ce. Su rger y correct s th e n on accom m odat ive or decom - pen sated com pon en t of th e deviat ion .
Intermittent Exotropia
In term it ten t exot ropia is in term it ten t divergen t deviat ion of th e visu al a xes. It is th e m ost com m on deviat ion seen in th e pediat ric popu lat ion (Fig. 12.4).
Presentation
On set is u su ally before age 5 years. Th e con dit ion is aggravated by fat igu e, sickn ess, an d daydream ing. Pat ien t s frequen tly squin t to recover align m en t an d elim in ate diplopia, esp ecially w ith exp osure to brigh t sun ligh t . At th e begin n ing it is usu ally seen on ly at dist an ce, but it m ay progress to affect th e n ear deviat ion . Am blyopia is rare. Pat ien t s u su ally m an ifest good stereop sis at n ear. Stereopsis at dist an ce can decrease as a resu lt of poor con t rol.
12 Strabismus 343
Fig . 12.4 Intermit tent exotropia.
In term it ten t exot ropia can be divided in to differen t t ypes based on th e differen ces bet w een th e n ear an d dist an ce angles of deviat ion :
Basic t ype: Th e n ear an d th e dist an ce angles of deviat ion are w ith in 10 prism diopters.
Divergence excess: Th e distan ce angle of deviat ion is larger th an th e n ear angle of deviat ion by 10 or m ore prism diopters. In pat ien ts w ith t ru e divergen ce excess, th e differen ce rem ain s after m on ocu lar occlusion ; if th e differen ce disappears, th e pat ien t h as sim ulated divergen ce excess.
Convergence insufficiency: Th e angle of exot ropia is 10 prism diopters or larger at n ear th an at dist an ce.
Differential Diagnosis
Convergen ce in sufficien cy, dissociated h orizon tal deviat ion
Management
Correct ion of any refract ive error. Min u s len ses in du ce accom m odat ion . Patch ing of th e n on deviat ing eye. Su rgical in dicat ion s in clu de deteriorat ion of con t rol an d stereoacu it y, diplopia, an d visu al con fusion . Su rger y u sually con sists of bilateral lateral rect us m u scle recession in pat ien t s w ith divergen ce excess, m edial rect u s m u scle resect ion in convergen ce in su fficien cy, an d m edial rect u s m u scle resect ion com bin ed w ith lateral rect us m uscle recession in th e basic t ype of in term it ten t exot ropia.
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Fig . 12.5 Constant exotropia.
Constant Exotropia
Con stan t exot ropia is usually associated w ith a decrease in visual acuit y, n eu rological disorder, disrupt ion of bin ocu lar vision , previou s st rabism us surger y, or cran iofacial abn orm alit ies (Fig. 12.5).
Presentation
In fan t ile exot ropia is a con st an t exodeviat ion presen t before age 6 m on th s, ch aracterized by a large angle of deviat ion . Th is con dit ion is usually associated w ith cerebral p alsy, n eu rological abn orm alit ies, or cran iofacial disorders. Sen sor y exo- t ropia is th e resu lt of disru pt ion of bin ocularit y an d reduced visual acu it y in on e eye. Con secu t ive or secon dar y exot ropia follow s previou s su rgical correct ion of an exodeviat ion .
Differential Diagnosis
Cran ial th ird n er ve palsy, slipped m edial rect u s m u scle, Duan e syn drom e, deteriorat ion of an in term it ten t exot ropia
Management
Alw ays ru le ou t n eu rological disorders, cran iofacial syn drom es, ocular abn or- m alit ies, or any abn orm alit ies in th e visu al path w ay associated w ith a decrease in vision . Treat m en t of am blyopia an d correct ion of refract ive errors are requ ired . Surger y con sist s of un ilateral or bilateral lateral rect us m u scle recession com bin ed w ith m edial rect us m u scle resect ion , depen ding on th e angle of deviat ion .
Pattern Strabismus
Horizon tal ch ange of align m en t from th e m idlin e w h en th e eyes are m oved be- t w een a 25-degree u pgaze, prim ar y posit ion an d a 25-degree dow ngaze. Th e in ciden ce of pat tern st rabism us is ~20%. Tw o prin ciples h ave been advan ced to exp lain th e cause of th e A an d V pat tern s: (1) oblique m uscle dysfu n ct ion or (2) rect us ext raocular m uscle overact ion or w eakn ess w ith ou t obliqu e m u scle dysfu n ct ion .
12 Strabismus 345
A
B
Fig . 12.6 (A) V pat tern. (B) A pat tern.
Presentation
An A pat tern is p resen t w h en th e eyes diverge 10 or m ore prism diopters bet w een dow ngaze an d u pgaze. A V pat tern is presen t w h en th e eyes converge 15 or m ore prism diopters bet w een u pgaze an d dow ngaze. Pat ien ts w ith pat tern st rabism u s m ay presen t w ith an om alou s h ead post ure, ocular torsion , an d overact ion or un - deract ion of th e obliqu e m u scles (Fig. 12.6).
Differential Diagnosis
Cran iofacial abn orm alit ies, cyclovert ical m u scle w eakn ess or overact ion , h orizon - tal rect u s m uscle overact ion , p seu do A an d V pat tern s in pat ien t s w ith accom m o- dat ive esot rop ia, h eterotopic or un stable rect u s ext raocu lar m uscles
Management
Ten don offset t ing su rger y of th e h orizon t al rect u s m u scles is an effect ive operat ion for collapsing A an d V pat tern st rabism us n ot associated w ith oblique m uscle dysfun ct ion w ith appropriate in dicat ion s. Th e m edial rect us m u scle is alw ays t ran s- posed tow ard th e apex of th e pat tern (up for A pat tern an d dow n for V pat tern ). Th e lateral rect us m u scle is t ran sposed in th e opposite direct ion . In th e presen ce of obliqu e m uscle dysfun ct ion , appropriate obliqu e m uscle w eaken ing procedures are in dicated .
Inferior Oblique Overaction
Un ilateral or bilateral over-elevat ion of th e addu cted eye is obser ved . Most cases of in ferior obliqu e overact ion are prim ar y an d n ot associated w ith oth er m uscle w eakn ess. Secon dar y in ferior obliqu e overact ion result s from w eakn ess of th e ip -
346 Color Atlas of Ophthalm ology
Fig . 12.7 Inferior oblique overaction.
silateral su perior oblique m u scle (an tagon ist m u scle) or th e con t ralateral su perior rect us m u scle (yoke m uscle). Approxim ately 65%of pat ien t s w ith in fan t ile esot ropia w ill develop in ferior oblique overact ion (Fig. 12.7).
Presentation
Th e prim ar y an d secon dar y overreact ion s of th e in ferior obliqu e m u scles h ave differen t clin ical presen t at ion s. In prim ar y in ferior obliqu e overact ion , on set is usu - ally after 1 year of age. It h as th e ten den cy to be bilateral an d sym m et ric. It is frequ en tly associated w ith a V pat tern . Usu ally, th ere is n eith er ver t ical deviat ion in th e prim ar y posit ion n or excyclotorsion , an d th e Bielsch ow sky h ead t ilt test is n egat ive. In con t rast , secon dar y in ferior obliqu e m uscle overact ion is associated w ith vert ical deviat ion in th e p rim ar y p osit ion an d excyclodeviat ion an d posit ive Bielch ow sky h ead -t ilt test .
Differential Diagnosis
Secon dar y cau ses of in ferior obliqu e overact ion , h eterotopic an d u n st able rect us ext raocu lar m uscles, orbital excyclotorsion , cran iosyn ostosis
Management
Th e t reat m en t of an overact ing in ferior obliqu e m u scle is a w eaken ing procedu re. In ferior oblique recession is th e preferred surgical procedure.
Dissociated Strabismus Complex
Dissociated st rabism u s com plex is an in term it ten t or m an ifest deviat ion of th e n on fixing eye. It is a dissociated m ovem en t th at violates th e Hering law ; as op - posed to t rue hypert ropia, n o com pen sator y m ovem en t of th e fellow eye is seen w h en th e fixing eye is covered . It m ay be ch aracterized by on e or m ore of th ese com pon en ts: ver t ical, h orizon t al, an d torsion al (Fig. 12.8).
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Fig . 12.8 Dissociated vertical deviation.
Presentation
Th e m ost com m on clin ical presen t at ion is hyperdeviat ion , exodeviat ion , an d excyclodeviat ion of th e n on fixing eye. Th e deviat ion m ay be com itan t or in com itan t , especially if associated w ith oblique m u scle dysfu n ct ion . Su ppression an d visual con fusion are com m on sen sorial abn orm alit ies. Oth er clin ical m an ifestat ion s m ay in clu de nyst agm us, tor t icollis, an d oblique m uscle dysfun ct ion .
Differential Diagnosis
Obliqu e m uscle dysfun ct ion
Management
Su rgical in dicat ion s in clu de decom pen sat ion , in crease in m agn it ude an d frequ en cy, an d tor t icollis. Bilateral surger y is alw ays recom m en ded u n less th ere is st rong eviden ce th at th e pat ien t w ill n ever p refer fixat ion w ith th e n on fixing eye. Large su perior rect us m uscle recession is th e procedu re of ch oice in pat ien ts w ith com it an t deviat ion s. Obliqu e m uscle su rger y is in dicated in pat ien ts w ith in com i- tan t deviat ion an d overact ing obliqu e m u scles.
Third-Nerve Palsy
Th ird -n er ve palsy con sists of isolated, m u lt iple, or com plete palsy or paresis of th e st ru ct u res in n er vated by th e th ird cran ial n er ve
348 Color Atlas of Ophthalm ology
Presentation (Fig. 12.9)
Com plete th ird -n er ve palsy is ch aracterized by exot ropia, hypot ropia, an d ptosis on th e side of th e affected n er ve. Th e clin ical presen t at ion of th e su perior th ird - n er ve-division palsy is hypot ropia an d ptosis of th e side ipsilateral to th e affected cran ial n er ve. In ferior th ird -n er ve-division p alsy presen t s w ith exot ropia, hyper- t ropia, an d pu pillar y dilat ion . Th ird -n er ve palsy can presen t as an isolated palsy of th e m edial rect u s m uscle, in ferior rect u s m uscle, sup erior rect us m u scle, in ferior obliqu e m uscle, levator m uscle, an d p upillar y sph in cter.
A
B
C
Fig . 12.9 (A) Complete third-nerve palsy. (B) Superior branch palsy. (C) Isolated m e - dial rectus palsy.
12 Strabismus 349
Th ird -n er ve palsy w ith pup illar y involvem en t can be a clin ical em ergen cy. Workup is required to ru le ou t sup raten torial m ass or basilar an eur ysm . In cases w ith ou t pupillar y involvem en t on e is required to rule ou t isch em ia, com pression , in flam m ator y process, n eu ropathy, an d m yon europathy.
In pat ien t s w ith congen it al th ird -n er ve palsy an d th ose w ith palsy secon dar y to lesion s in th e cavern ous sin us, an eu r ysm s, m en ingiom a, an d t raum a can develop aberran t in n er vat ion to th e ciliar y ganglia, levator m u scle, an d ext raocu lar m uscles.
Differential Diagnosis
Rest rict ion , Graves oph th alm opathy, orbit al fract ure, fibrosis of th e ext raocular m u scles, m yotoxicit y, m yasth en ia, ch ron ic progressive extern al oph th alm oplegia, congen it al absen ce of th e ext raocu lar m u scles
Management
Cases secon dar y to diabetes, hyper ten sion , or m igrain e u su ally com pletely resolve in 1 to 12 w eeks. Non su rgical t reat m en t in clu des occlusion , prism s, an d bot u lin u m toxin . Su rgical t reat m en t depen ds on th e deviat ion in th e prim ar y posit ion an d m u scle fun ct ion . Weaken ing of th e ip silateral lateral rect u s m uscle is n ecessar y in cases of com plete th ird -n er ve palsy. Su rgical t reat m en t is ch allenging in cases w ith com plete th ird -n er ve palsy or w h en several ext raocu lar m u scles are affected .
Fourth-Nerve Palsy (Superior Oblique Palsy)
Fou rth -n er ve palsy is a congen it al or acquired paralysis of th e su perior obliqu e m u scle. Congen it al cases m ay be secon dar y to abn orm alit ies of th e ten don , in - cluding laxit y, absen ce, or an om alous in sert ion . Acqu ired cau ses in clude t raum a, com pression , isch em ia, in filt rat ion , an d h em orrh age. Tum ors sh ou ld alw ays be su spected in p at ien ts w ith acqu ired bilateral su perior obliqu e palsy (Fig. 12.10).
A
Fig . 12.10 (A) Unilateral superior oblique palsy. (Continued on page 350)
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B
Fig . 12.10 (Continued) (B) Bilateral superior oblique palsy.
Presentation
Un ilateral su perior obliqu e palsy is ch aracterized by hypert ropia in addu ct ion , posit ive h ead -t ilt test , V p at tern , an d excyclot ropia. Oth er clin ical sign s in clu de posit ive th ree-step test , large fusion al am plit udes, an d facial asym m et r y w ith hypoplasia con t ralateral to th e side of th e palsy. Bilateral palsies are ch aracterized by reverse hyp ert rop ia, posit ive h ead t ilt test , V pat tern , an d excyclot ropia larger th an 10 degrees. Pat ien t s w ith sym m et rical bilateral su perior obliqu e palsy usu - ally h ave lit tle or n o ver t ical deviat ion in th e prim ar y posit ion .
Differential Diagnosis
Skew deviat ion , Graves oph th alm opathy, an d prim ar y in ferior oblique overact ion
Management
Many pat ien ts are able to com pen sate for th e ver t ical deviat ion , especially th ose w ith long-stan ding su perior obliqu e palsy. Surgical t reat m en t depen ds on th e am ou n t of deviat ion in th e prim ar y posit ion , th e size of deviat ion in th e vert ical plan e (upgaze an d dow ngaze), an d th e ipsilateral gaze (field of act ion aw ay from th e affected superior oblique m uscle) an d degree of dysfun ct ion of th e sup erior obliqu e m u scle. Pat ien t s w ith less th an 15 prism diopters of ver t ical deviat ion in th e prim ar y posit ion can be t reated w ith su rger y on on e m u scle. In pat ien t s w ith sign ifican t excyclotorsion , su perior oblique m uscle t ucking or an terior lateraliza- t ion of th e an terior fibers of th e superior oblique ten don m ay be h elpfu l.
Sixth-Nerve Palsy (Lateral Rectus Muscle Palsy)
Sixth -n er ve palsy result s in paralysis of th e lateral rect us m u scle.
Presentation
In com it an t esot ropia is larger in th e abdu cted field of act ion of th e affected lateral rect us m u scle. Et iology in cludes t rau m a, com pression , an d in fect ion . New born s m ay presen t w ith a tem p orar y paralysis (Fig. 12.11).