Hjd

• Embryology of the eye

  • Lens
  • Epithelium
  • Vitreous
  • Retina
  • Optic nerve derived from ectoderm
  • Extraocular muscles
  • Endothelium
  • Sclera
  • Trabecular meshwork derived from mesoderm
  • Optic nerve
  • Pupillary muscles
  • Iris epithelium from neural crest cells
• Components of the orbit

  • 7 bones
  • 7 muscles
  • 7 nerves
• The orbital volume is approximately 30 ml, with the eyeball occupying only 6 ml
• The thinnest wall of the orbit is the medial wall, but the most commonly fractured is the inferior wall
• Classic triad of inferior wall fracture

  Diplopia<|>Infraorbital anesthesia<|>Enophthalmos
• Ophthalmic measurements


  Axial length around 24 mm<|>Anterior chamber depth of 3 mm<|>Corneal thickness of 540 microns on average
• The critical angle for visualizing the angle structures is 46 degrees
• Thyroid eye disease


  Most common presentation is lid retraction
• First muscle to become restricted in thyroid eye disease

  Inferior rectus
• The characteristic "coke bottle" enlargement of the muscle belly occurs with sparing of the tendon in thyroid eye disease
• Common pediatric tumors


  • Dermoid cyst
  • Retinoblastoma
• Metastatic tumors to the pediatric orbit are most often from neuroblastoma
• The most common orbital tumor in adults that can cause enophthalmos is a metastasis from breast cancer
• Ptosis


  Drooping of the upper eyelid, can be congenital or acquired
• Etiologies of ptosis


  • Aponeurotic
  • Myogenic
  • Neurogenic
  • Mechanical
• Surgical management of ptosis

  1. Assess LPS muscle function

  2. If LPS is strong, perform resection

  3. If LPS is weak, perform frontalis suspension
• Lacrimal drainage system components

  • 7 components
• Congenital nasolacrimal duct obstruction is a common condition in children
• Management of congenital nasolacrimal duct obstruction

  1. Digital sac massage

  2. Probing

  3. Dacryocystorhinostomy if needed
• Cataract is the leading cause of blindness worldwide, responsible for 50-70% of cases globally
• Age-related cataract


  Most common type, predominantly caused by ultraviolet light exposure
• Nuclear cataracts can cause hemeralopia or day blindness due to pupil constriction
• Nuclear cataracts can cause index myopia due to increased refractive index
• Cortical cataracts


  Uniform in appearance
• Posterior subcapsular cataracts


  Cause maximum visual handicap and glare
• The most common type of cataract in children is the zonular cataract
• It is important to ensure clear optical access during the critical period of fixation between 2 to 4 months of age
• Complicated cataracts due to various eye diseases are usually posterior subcapsular, polycrystalline, and have a breadcrumb appearance
• Intraocular lens (IOL) implantation

  Preferred after cataract extraction over thick, magnifying glasses
• Phacoemulsification with a foldable IOL


  Preferred modern cataract surgery technique
• Small incision cataract surgery (SICS) is a viable alternative in settings with limited resources
• SICS is a common and economical surgical technique performed in India and other developing countries
• Small incision cataract surgery (SICS)


  1. Make small, multi-plane incision of less than 6 mm

  2. Does not require stitches
• SICS provides good visual outcomes comparable to phacoemulsification, but at a lower cost
• Femtosecond laser-assisted cataract surgery (FLACS)


  Uses a laser to create a perfectly circular capsulotomy and precise incisions
• FLACS is more expensive than SICS but can offer additional advantages
• Accurate calculation of the intraocular lens (IOL) power is crucial
• The IOL power calculation depends on the patient's axial length and corneal curvature, measured using biometry
• The type of IOL material, such as hydrophobic acrylic, can impact the rate of posterior capsular opacification
• Postoperative complications


  • Secondary cataract
  • Cystoid macular edema
  • Endophthalmitis