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pediatric ophthalmology

1. Essential Infantile Esotropia Dr. Jyoti Acharya

2. Previous years DNB/MS exam questions ! Dec 2018 Define essential infantile esotropia? Give at least four differential diagnosis of essential infantile esotropia and give at least two differentiating features among them. 2+8 June 2019 What are the features and differential diagnosis of infantile esotropia? When it should be operated and its prognosis for binocular single vision (BSV). 5+5 June 2020 Describe clinical features,investigation,indication and surgical management of infantile esotropia and its post-operative complications. 1+2+2+3+2 June 2021 a) Define and classify esotropia. b) Management of a 6 year old patient with esotropia. ( (2+2) +6 )

3. Esodeviation Esophoria Esotropia Decompensating Compensated Convergence excess Divergence weakness Basic Incomitant Concomitant Paralytic Restrictive Spastic Neurogenic Myogenic Accommodative Non A ccommodative Essential infantile Essential acquired Acute concomitant Microtropia Cyclic esotropia Sensory esotropia Nystagmus blockage syndrome Refractive Normal AC/A Non refractive high AC/A Hypoaccommodative reduced NPA Partially accommodative

4. DEFINITION ESSENTIAL INFANTILE ESOTROPIA "Congenital" or essential infantile esotropia has been described as inward deviation of both eyes having the following characteristics: (Von Noorden 1988 ) 1 ) Onset birth to six months 2 ) Large angle (greater than 30 prism dioptres) 3 ) Stable angle 4 ) Asymmetric Optokinetic Nystagmus (58%) 5 ) Normal central nervous system

5. Synonyms Essential infantile ET Infantile ET Congenital ET Etiology Remains relatively uncommon Common to family history of strabismus Decreased binocular function reported in parents of patients with infantile ET Other links Maternal cigarette smoking Low birth weight

6. Pathophysiology Worth’s theory (1903) The cause of squint is a defect in fusion faculty ( Worth did not make any distinction between sensory and motor fusion). What Worth wrote ? When fusion faculty is inadequate the eyes are in a state of unstable equilibrium , ready to squint either inward or outward on slight provocation. Chavasse theory The cause of squint is defect in walking faculty (incoordination of impulses to the muscle). He believed that the primary problem was mechanical and curable if deviation could be eliminated in infancy.

7. Q. Who said this ? ‘We know that bald persons descend from bald persons ,blue eyed persons from blue eyed persons and squinting children from squinting parents.’ Worth Chavasse Von noorden Hippocrates

8. ESSENTIAL INFANTILE ESOTROPIA Clinical features Onset < 6/12 Stable ET > 30 PD and usually considerably larger No significant refractive error Abduction usually normal Note if contracture of MR occurs LR may appear underacting Poor prognosis for bifoveal BSV Associated signs Cross fixation Inferior oblique over action Dissociated vertical deviation Nystagmus ( latent / manifest latent waveforms) Naso temporal asymmetry of optokinetic nystagmus Abnormal head posture (less common)

9. CROSS FIXATION Eye alternates fixation at midline. Patient uses L eye on R gaze R eye on L gaze Appears as though patient has a LR deficit. Need to perform duction or dolls head. M ay prevent amblyopia but not always achieve this.

10. INFERIOR OBLIQUE OVERACTION Over action of one or both inferior oblique muscle is common. IOOA can coexist as well as confused with DVD , requiring differential diagnosis.

11. DISSOCIATED VERTICAL DEVIATION Part of dissociated strabismus complex (DSC) Dissociated Vertical Deviation ( DVD ) Dissociated Horizontal Deviation (DVD) Dissociated Torsional Deviation ( DTD) A condition associated with infantile ET. Cause appears to be related with early disruption of BSV. Occurs at 2.5 to 3 years of age.

12. Characteristics Eye under cover progressively elevates with continued dissociation. Elevated eye returns to original position on removal of cover. Eye may extort as it elevates ; intorts as it resumes original position (DTD ). Eye may abduct on elevation; adducts as it resumes original position (DHD ). Almost always bilateral , can be asymmetrical.

13. LATENT NYSTAGMUS Nystagmus which is elicited with occlusion of one eye or dissociation. Often occurs with DVD and IOOA.

14. OKN ASYMMETRY In normal subjects optokinetic response elicited by a rotating OKN drum consists of a smooth pursuit movement in the direction of moving stripes followed by a corrective saccade in opposite direction This pursuit movement occurs with equal facility regardless of the fact drum moves nasal to temporal or temporal to nasal side. But in ET this pursuit movements are irregular. Difficult to elicit when drum moves from nasal to temporal direction. Its presence indicates disruption of BSV during period of visual maturation (3-4 months).

15. ABNORMAL HEAD POSTURE AHP Generally face turn to R or L or tilt Develops secondary to either Nystagmus DVD IOOA

16. Q ) A 6 year-old girl was referred to CIMS BSP . She was previously under the care of another hospital and had squint operation for a convergent squint which was present since infancy. Her visual acuity was 6/9 in the right eye and 6/6 in the left. Cover test revealed a small right exophoria of 5 PD. The covered eye showed elevation and nystagmus was observed when either eye was covered. The nystagmus was absent when both eyes were uncovered . The following are true: T he esotropia prior to the surgery was likely to be more than 30 PD. T he patient is likely to have high hypermetropia in the right eye. B inocular single vision is usually better than 60 degrees of arc. A symmetrical optokinetic nystagmus is common. F urther surgery is likely to be needed. 1,4

17. DIFFERENTIAL DIAGNOSIS Congenital 6 th nerve palsy Duane retraction syndrome Nystagmus blockage syndrome Early onset accommodative ( fully or partially) ET

18. ESSENTIAL INFANTILE ESOTROPIA MANAGEMENT AIM Improve visual acuity if amblyopia is present. Surgically intervene to improve cosmesis and provide BSV.

19. 1. OPTICAL Infantile ET tend not to be hypermetropic . If >= 3DS consider prescribing. 2. OCCLUSION To ensure amblyopia is treated BEFORE surgical intervention. Prescribe patching regime that considers waking hours of infant. Ensure you monitor VA and potential amblyopia post operatively. AET - Equal vision LET - left amblyopia may be present Left eye not taking up fixation – LET dense amblyopia

20. 3. SURGERY Goal of t/t includes Excellent VA in both eye. Perfect single binocular vision in all gaze position at near & distance. Cosmesis. Alignment of with in 10 PD of orthotropia with some degree of BSV ( that is microtropia ). Indications for surgery A stable & sufficiently large angle deviation. Absence of an accommodative factor. Alternating fixation behaviour after t/t of amblyopia.

21. Time of surgery Debate exist regarding Very early : 3-4 months. Early : < 2 years : general consensus – we should operate < 2 years to achieve BSV. Surgical options U/L MR recession/LR Resection. Bi medial recession. 3 muscle surgery Bi medial recession with LR resection / +- IO recession / Anterior positioning.

22. SURGERY Points to remember Surgical dose - 1 mm surgery on MR corrects 3-4.5 PD deviation while 1 mm on LR corrects 2-3 PD. Early v/s late surgery - In infants posterior segment is still developing so results of surgery is unpredictable. Single v/s multiple muscles - Multiple muscles approach can give the opportunity to reduce recessions and distribute them amongst all horizontal recti. A minimal and harmonious dosage may reduce the incidence of incomitances, with excellent results even in large esodeviations .

23. Complications of strabismus surgery for ET Intraoperative Operating wrong eye Operating wrong muscle Wrong surgery performed Hemorrhages Scleral perforation Splitting of muscle fibres Loose suture and partial thickness suture in muscle Central sag Lost or slipped muscle Muscle sheath , tenon’s rupture and fat prolapse Post operative Vomiting Orbital cellulitis Suture abscess Suture granuloma Tenon’s prolapse and conjunctival cyst Dellen Anterior segment ischaemia Under and over corrections Consecutive exotropia