Pediatrics opthalmology

• Anatomy of the orbit:

  • The orbit acts as a socket that contains and protects the eye
  • It has the shape of a pyramid, with the base in front and the apex behind
  • Seven bones contribute to the bony orbit: frontal, zygomatic, temporal, maxillary, sphenoid, ethmoid, palatine, and lacrimal
  • The lateral aspect is the strongest wall of the orbit as well as the anterior aspect
  • The smallest part is the orbital apex, and any lesion in the apex is very dangerous as it can press on vessels and nerves passing through it
  • The weakest parts of the orbit are the floor and medial wall
• Most common fracture of the orbital wall is the orbital floor (blowout fracture) due to blunt trauma, causing high intraocular pressure (IOP)

  • The patient will complain of diplopia (vertical diplopia)
  • The medial orbital wall and ethmoid sinus are separated by a thin straight bone called lamina papyracea, which is a common source of infection
  • The most common site of infection is the medial wall
  • A patient with sinusitis commonly presents with orbital cellulitis
• Important openings in the orbit:

  • Optic foramen: optic nerve and ophthalmic artery run through it
  • Superior orbital fissure:
  • Between lesser and greater wings of sphenoid
  • Contains cranial nerves III, IV, and VI, Lacrimal nerve, Nasociliary nerve, Superior ophthalmic vein, and Inferior ophthalmic vein
  • Inferior orbital fissure: contains Infraorbital nerve and Infraorbital vessels
• Extraocular Muscles:

  • There are 4 recti muscles (Superior, Inferior, Medial, Lateral) and 2 oblique muscles (Superior, Inferior)
  • All muscles are supplied by the Oculomotor nerve except the superior oblique (Trochlear nerve) and lateral rectus (Abducent nerve)
  • Axis of rotation (FICK'S):
  • X (horizontal) axis: lies horizontally when the head is upright, responsible for elevation/depression
  • Y (antero-posterior) axis: responsible for torsional movements (extorsion/intorsion)
  • Z (vertical axis): responsible for adduction/abduction
• Laws that control extraocular muscle movement:

  • Sherrington’s law: a muscle will relax when its antagonist muscle is activated
  • Law of reciprocal innervation states that innervation and contraction of a given extraocular muscle are accompanied by a reciprocal decrease in innervation and contraction of its antagonist
  • Hering’s law of equal innervation: yoke muscles are innervated equally during eye movement
• Normal binocular single fusion:

  • When a normal individual fixes visual attention on an object, the brain integrates images from both eyes into a single image
  • Stereopsis is the perception of depth created by the brain integrating slightly different images from each eye
• Strabismus:

  • Occurs when both eyes do not look at the same place at the same time, leading to misalignment
  • Eyes may turn in, out, up, or down and can be present in one or both eyes
  • Causes include lack of coordination between eye muscles, nerve problems, and brain control issues
  • Risk factors include family history, refractive errors, and medical conditions like Down syndrome or cerebral palsy
  • Types of strabismus include Esotropia, Exotropia, Hypertropia, and Hypotropia, which can be constant or intermittent, bilateral, unilateral, or alternating
• Development of strabismus:

  • Can be congenital (developing during infancy) or acquired (developing in adulthood)
  • Strabismus is not the same as Amblyopia (lazy eye), which is a vision problem
• Treatment of strabismus:

  • Options include eye patching, eyeglasses or contacts, prisms, vision therapy, eye surgery, and Botox therapy
• Manifest convergent squint can be Concomitant (inward squint that does not vary with direction of gaze) or Incomitant (squint varies in size with direction of gaze)
• Types of esotropia strabismus:

  • Congenital esotropia is noted before 6 months of age and is characterized by:
  • Large alternating angle of deviation
  • Primary oblique muscle dysfunction (hypertropia)
  • Lack of Binocular Vision
  • A or V pattern:
  • A pattern: relative convergence on up gaze and relative divergence on down gaze
  • V pattern: relative divergence on up gaze and relative convergence on down gaze
  • Acquired Esotropia has two forms:

  A. Begins between ages 1-3 years, usually manifesting at age 2, leading to sensory adaptation syndrome in the form of unilateral strabismus
• B. Manifests between ages 3-7 years, less frequently encountered, resulting in sudden double vision
• Micro-strabismus:

  • Unilateral esotropia with minimal cosmetic effect, an angle of deviation of 5 degrees or less
  • Often diagnosed late, around age 4-6, resulting in severe Amblyopia
  • Treatment limited to occlusion therapy to correct amblyopia
• Accommodative esotropia:

  • Angle of deviation is larger with close objects than with distant objects
  • Corrected with bifocal eyeglasses
  • Residual angle of deviation may remain despite eyeglasses, but visual axes may improve for good binocular vision
• Accommodative/Non-accommodative Esotropia:

  • Accommodative Esotropia:
  • Normal response to approaching object is the triad of the near reflex: convergence, accommodation, and miosis
  • Excessive accommodation can lead to esotropia in young children
  • Average age of onset is 2.5 years
  • Usually reversible with correction of refractive error
  • Non-accommodative Esotropia:
  • Accounts for 50% of childhood strabismus
  • Most are idiopathic
  • May be due to monocular visual impairment or divergence insufficiency
• Exotropia:

  • Less common than esotropia, usually acquired, more in adults
  • Less frequently leads to amblyopia because it is often alternating
  • Occasionally results in "panorama vision" with an expanded binocular field of vision
  • Intermittent exotropia:
  • Most common form of divergent strabismus
  • Angle of deviation present only when patient gazes into the distance
  • Normal binocular vision in near fixation
  • Secondary exotropia:
  • Occurs with reduced visual acuity in one eye resulting from disease or trauma
  • Consecutive exotropia:
• • Occurs after esotropia surgery, often overcorrected
• Incomitant (paralytic):

  • Degree of misalignment varies with direction of gaze
  • One or more extra-ocular muscles or nerves may not be functioning properly
  • May indicate nerve palsy or extra-ocular muscle disease
• Isolated nerve palsies:

  • Systemic causes (DM, hypertension), orbital disease, trauma, raised intracranial pressure
  • Extra-ocular muscle diseases: Thyroid eye disease, Myasthenia gravis, Ocular myositis, Ocular myopathy, Brown's syndrome
• Cranial nerve palsy:

  • Each nerve may be affected at any point along its course from brainstem nucleus to orbit
  • In most cases, there is not a complete loss of action of a muscle but a partial loss
  • 3rd nerve palsy: Ptosis, Dilated pupil, Limitation of eye movement
  • 4th nerve palsy:
  • Defect maximal when patient looks down when left eye is adducted
  • Vertical diplopia, 2 visual fields separated vertically
  • 6th nerve palsy:
  • Esotropia on distance fixation, usually unilateral
  • Horizontal diplopia
• Treatment:

  • Correction of myopia, part-time occlusion of deviating eyes
  • Surgery if progressing or if control is poor
  • Lateral rectus recession & medial rectus resection
• Amblyopia:

  • Vision in one eye is reduced due to eye and brain not working together
  • Developmental problem in the brain
  • Presentation:
  • Most cases are asymptomatic
  • In severe cases: poor depth perception, poor spatial acuity, low sensitivity to contrast, reduced sensitivity to motion
  • Causes: congenital cataract, refractive error, squint, opacity in one eye, congenital retinal detachment
  • Amblyopia secondary to suppression:
  • Constant suppression in strabismus can lead to severe amblyopia
  • Treatment: correcting optical deficit, forcing use of the amblyopic eye
• P/E and Tests for strabismus:

  • Observe features that simulate squint: Epicanthus, Facial Asymmetry
  • Assess Visual Acuity
  • Perform Cover/Uncover Test to detect tropia
  • Alternating cover/uncover test for heterophoria
  • Hirschberg test
  • No shift on cover testing means no tropia
  • Tropias versus Phorias
• Tropias versus Phorias:

  • Tropia: always deviated (Ex: Exotropia, Esotropia, Hypertropia, Hypotropia)
  • Phoria: sometimes deviated (Ex: Exophoria, Esophoria, Hyperphoria, Hypophoria)
• Alternate Cover test:

  • Occluder is moved to and front between the eyes
  • If eye has been uncovered moves, then there is a latent squint
  • Used for detection of phorias
• Treatment for strabismus:

  • Early detection is the most important prognostic sign to prevent permanent visual deficits
  • Most children recover from amblyopia by around age 10 with patches and corrective glasses
  • Primary therapeutic goal for strabismus is comfortable, single, clear, normal binocular vision at all distances & directions of gaze
  • Advanced strabismus is usually treated with a combination of eyeglasses or prisms, vision therapy, and surgery
• Strabismus surgery:

  • Principle of surgery is to realign the eyes by adjusting the position of the muscles on the globe or by shortening the muscle
  • Access to muscle is gained by making small incision in conjunctiva
  • Moving muscle insertion backwards on globe (recession) weakens muscle
  • Removing a segment of muscle (resection) strengthens action
  • Botulinum toxin could be used for single muscle weakening
  • Surgery is not an alternative to glasses and patching when treating amblyopia
• Prognosis of strabismus:

  • Early diagnosis and treatment can usually correct the problem
  • 90% will have good vision & maintained if treated before 4 years old
  • Delayed treatment may lead to permanent vision loss in one eye
  • After surgery, eyes may look straight but vision problems can remain
  • Children may still have reading problems, and for adults driving may be more difficult. Vision may affect ability to play sports
  • Many children with strabismus or amblyopia may need to be monitored closely
• ReTinopathy of Prematurity:

  • Growth of abnormal new vessels that tend to leak or bleed, leading to scarring of the retina
  • Risk factors include low birth weight, low gestational age, and extended supplemental oxygen
  • Treatment varies from mild cases correcting themselves to surgery to prevent vision loss or blindness
• Congenital Cataract:

  • Lens opacity present at birth
  • Classified by morphology (lamellar, polar, sutural, etc.) and etiology (metabolic, infectious, anomalies, toxic)
  • Treatment urgency depends on severity, with surgery for moderate to severe cases affecting vision
• Retinoblastoma:

  • Most common primary malignant intraocular cancer in children
  • Inherited as AD but most cases are sporadic
  • Presents with a white-pink mass protruding from the retina into the vitreous cavity
  • Treatment includes removal of the eye in advanced cases, radiotherapy, cryotherapy, photocoagulation, and chemotherapy for metastasis
  • Prognosis includes an overall mortality of 15% and a risk of developing a second primary tumor
• Congenital Glaucoma:

  • Birth defect in the development of the eye angle leading to increased intraocular pressure and optic nerve damage
  • Diagnosed within the first year of life
  • Treatment aims to lower intraocular pressure through medical (topical eye drops, oral medications) and surgical (filtering surgery, laser surgery) interventions
• Congenital Ptosis:

  • Drooping eyelid present at birth or within the first year of life
  • Causes include idiopathic, third cranial nerve palsy, Horner syndrome, birth trauma, myotonic dystrophy, pseudotumor of the orbit
  • Treatment ranges from observation to surgical intervention
• Epiphora:

  • Overflow of tears onto the face due to blocked tear ducts or excessive tear production
  • More common in infants under 12 months or adults over 60 years
  • Treatment may involve gently massaging tear ducts or medical/surgical interventions
• Nystagmus:

  • Involuntary eye movement acquired in infancy or later in life
  • Causes include various conditions affecting the eyes or nerves
  • Diagnosis involves eye movement recordings and various exams
  • Treatment options include medications like Baclofen and Gabapentin, as well as other drugs for improvement