Constant esotropia

Question 1

what is a primary constant esotropia

Answer 1

the esotropia is the initial defect and is present under all conditions

Question 2

what are the two types of primary constant esotropia

Answer 2

• constant esotropia

with a accomodative element

without accomodative element

Question 3

what is constant esotropia with a accomodative element

Answer 3

onset 1-3 years

the accomodative element may be

refractive- uncorrected hypermetropia - cant see things close to them

esotropia increases on accomodation without glasses

esotropia decreases with hypermetropic perscription but not eliminated

Question 4

what are the reasons for a constant esotropia with a accomodative element

Answer 4

due to high aca ratio - esotropia for near is more than 10 diopters greater than for distance

esotropia reduces for near with +3 diopters (relax accomodation) but no eliminated

a combination of refractive and high aca ratio

a large deviaiton for near persists after refractive correction but reduces with +3.00ds

note - a high hypermetropia can decrease the esotropia by a significant amount in the presence of a normal ac/a ration and may not have an abnormal accomodative element

Question 5

what are the types of constant esotropia with a accomodative element

Answer 5

acquired non accomodative esotropia

acquired esotropia with myopia

Question 6

describe acquired non accomodative esotropia

early onset

Answer 6

early onset

onset 6 months - 2 years

amblyopia common

poor prognosis for restoring bsv

deviation may increase with time

often require surgery

Question 7

what are the two types of acquired non accomodative esotropia

Answer 7

early onset (6 months)
and
late onset normo sensorial/ acute- onset concomitant esotropia)

Question 8

describe constant esotropia w a accomodative element

late onset

Answer 8

late onset

onset = 2-8 years

may be caused by minor injury/ short occlusion of 1 eye

onset may be intermittent causing constant and large deviation

signs- closure of 1 eye/ dipolopia

good prognosis for restoring bsv

Question 9

describe how esotropia can cause myopia

Answer 9

a type of constant esotropia without a accomodative element
esotropia with myopia

moderate degree -6 to 12ds

gradual onset and present in young adults

esotropia is greater for distance

signs - c/o diplopia

require prism/ surgical management

Question 10

describe how a high degree of myopia can cause a constant esotropia without a accomodative element

Answer 10

• esotropia with myopia

high degree (- 15DS)

Very gradual onset

often 1st present in adult life

associated with progressive myopia (elongation of the globe)

sings rarely c/o diplopia

restricted ocular motlility llimitation of abduction (due to a enlarged glove compressing the lateral rectus

Question 11

describe the indicidence of esotropia

Answer 11

esotropia is more common than exotropia in childhood

prevalance of esotropia in school children= 0.3% —— 3.6%

incidence of esotropia 111 per 100.000 people < 19 years

Question 12

what are risk factors for esotropia

Answer 12

low birth weight < 3000 gram

prevelance of strabismus 12-36%
normal paediatric populaition 0.1 to 6%

premature birth before 37 gestational weeks

large head circumfrence

children with chromosomal abnormalities or syndromes

Question 13

describe the genetic correlations found for esotropia

Answer 13

primary esotropia

linkage to chromosone 7, locus stbmsi

this locus only accounts for a proportion of cases

Question 14

what tests would you conduct to confirm the presence of a constant left esotropia

Answer 14

• va
• ct

asess potential for bsv- convergence, bg/wl, synoptophore , sterotest

pct

fundus and media check

refraction under clycloplegia

Question 15

what other tests would you perfrom to decide upon managment

Answer 15

asess fixation

investigation of suppression

density and area

further investigation of potential for bsv and establish maximum angle of deviation before surgery

prism adaptation test

Question 16

how would you asess suppression

Answer 16

sbisa bar

repeat at each visit when treating amblyopia

area
prisms or synoptophore

post opperative dipolopia test

indentify risk of dipolopia after surgery or bt injection

Question 17

what is the post ooperative diplopia test

Answer 17

used in patients with no demonstrable potential for bsv

need to be old enough for subjective testing

method

use prisms in free space near and distance with glasses

aim

under and over correct the angle of deviaiton up to 20 diopters

asess risk of moving image out of suppression scotoma and causing intractable diplopia

record prism at which diplopia appreciated or graphic pethod

Question 18

what are the managment options for patients with a primary esotropia with and without a accomoative element

Answer 18

obtain optimum or equal va

restore normal bsv if possible

maintain ac if present

improve ocular alignement if no potential for bsv

Question 19

what is the prism adaptation test

Answer 19

pat - asess potential for bsv

determine max angle of deviation before surgical correction

aim to fully correct or slightly over correct

who is it suitable for

children from the age of 3 years

require equal/ near equal va

va of 0.300logMAR (6/12) or better

angle of deviation less than or equal to 40 diopters

no vertical deviation

Question 20

how would you perform the prism adaptation test

Answer 20

measure the size of deviation for near and distance

fully or slightly over correct deviaiton for distance with fresnel

• split diopteers between two eyes

if deviaiton is greater for near by diopters or more than the near angle should be corrected

measure size of deviaiton again to ensure fully corrected before send patient home

explanation

• explain reasons for the PAT

emphasise the importance of full time wear of glasses with prisms

review in 1-2 weeks to reasess potential for bsv and measure size of deviation

Question 21

what are the 2 responses you can have a to a prism adaptation test

Answer 21

responders

bsv response - maybe microtropia

aim of surgery - correct max angle measured

non responders

no bsv

aim of surgery - correct original angle measured

Question 22

what is the outcome of managment for patients with a primary constant esotropia

Answer 22

the age of onset is an important factor for restoring bsv following surgery

et without an accomodative element

• onest - less than 30 months - unlikely to develop steropsis following ocular aligment

onset - more than 44 moths and no amblyopia - more likely to devlop a good level of steroacuity

et with a accomodative element

onset- more than 36 months- more likely to develop good level of stereopsis

Question 23

what are the management options for patients with no poitential for bsv

Answer 23

small deviaiton - no pychoscial issue

treat any amblyopia

observe until approc 7-8 years and no risk of amblyopia

treatment to improve ocular alignment - aim

make deviaiton less noticeable

slightly under correct angle by approx 10 diopters

perfrom post op diplopia test in all patients older than 7 years

Question 24

what are potential management options

Answer 24

botulinum toxin injection

patients with a high risk of post op diplopia / unsuitable for surgery

controversial in young children - require repeat injections

surgery - unilateral medial rectus recession/lr resection - deviation approximatley equal near and distance

bilateral mediul rectus recession is the deviaiton is greater for near

Question 25

how does surgery differ for small to moderate angles

Answer 25

surgery for small to moderate angles (15-35) perform 1 muscle operation

unliateral medial recession

large angle - 50- 70 diopters perform 2 muscle operation

bilateral medial rectus recession

medial rectus recession/ LR resection

greater than or equal to 70

perform 3 muscle operation
bilateral medial rectus recession/ lr resection

refractive surgery to correct hypermetropia

limited litretaure and long term data

kirwan et al al no real change in pre-op angle with glasses and pre- op

adovocated in adults