Describe the process to assess Visual Acuity
Numerator/Denominator?
_______________: NO refractive errors
Emmetropia: NO refractive errors
_______________: Shortsighted
How is this corrected?
Myopia: Shortsighted ( Reading is ok, Distance objects difficult)
Corrected with a CONCAVE (Divergent) Lens
_______________: Longsighted
How is this corrected?
Hyperopia (Hypermetropia): Longsighted (Optical power too weak for axial length)
Corrected with a CONVEX (Convergent) Lens
_____________: Loss of accommodative power with increasing age
How is this corrected?
Presbyopia: Loss of accommodative power with increasing age (Lens becomes stiffer, doesn’t move as well)
Corrected w/ BIFOCALS
______________: decreased vision that results from abnormal visual development in infancy/childhood
Amblyopia: decreased vision that results from abnormal visual development in infancy/childhood
______________: vision in one eye is worse than the vision in the other due to a difference in refractive error
Anisometropia: vision in one eye is worse than the vision in the other due to a difference in refractive error
- In children => interruption of visual development (Amblyopia) and Squint
- In adults => eye strain
_______________: blurred vision due to irregular shape of the cornea => difficult to get light in focus on the retina
Astigmatism: blurred vision due to irregular shape of the cornea => difficult to get light in focus on the retina
Pathology/Risks associated with Myopia?
Pathology:
- Tilted disk
- Atrophy of Chorioretinal Capillaries and Retinal pigment epithelium
Risks:
- Retinal Degeneration and Detachment
- Choroidal Neovascularization
- Primary Open-angle Glaucoma (POAG): bigger eye => cells are stretched out => difficult to see changes due to glaucoma
Pathology/Risks associated with Hypermetropia (Hyperopia)?
If baby is very Hyperopic (> 3.50 D) – greater risk of developing Strabismus (Weakness of eye muscles)
Risk factors
- Family history
- Maternal smoking during pregnancy
- Prematurity / low birth weight
- Acute-Angle Closure Glaucoma
If a baby is very Hyperopic (_________) – greater risk of developing ________
If baby very Hyperopic (> 3.50 D) – greater risk of developing Strabismus (Weakness of eye muscles)
Cranial Nerves involved with accommodation?
CNII (Optic Nerve) and CNIII (Occulomotor Nerve: Innervates Ciliary Muscles)
_________________________________: Remove corneal surface epithelium w/ a microkeratome
PRK (Photorefractive Keratectomy): Remove corneal surface epithelium w/ a microkeratome
- Corneal epithelium heals in days post-op
_________________________________: Remove corneal surface epithelium w/ dilute alcohol and push back the epithelium
LASEK (Laser Epithelial Keratomileusis): Remove corneal surface epithelium w/ dilute alcohol and push back the epithelium
- Combines aspects of PRK + LASIK
_______________________________: Microkeratome instrument (blade or laser) applied to corneal stroma to create a corneal flap. Flap is lifted and carefully repositioned
LASIK (Laser-Assisted In Situ Keratomileusis): Microkeratome instrument (blade or laser) applied to corneal stroma to create a corneal flap. Flap is lifted and carefully repositioned
Advantages/Disadvantages of various forms of Refractive Surgery?
Overall Risks of Refractive Surgery
Overall Risks:
- Regression, under-correction
- Risk of infection
- Dry eyes
- Flap problems
- Corneal haze, glare, trouble with driving at night (halos around lights)
Causes/Management of Strabismus?
Causes:
- Refractive Error (Hyperopia, Myopia, Anismetropia (Different refractive error in each eye)
- Family history of squint (Congenital Condition)
- As an Adult: Trauma or Cranial Nerve Palsy
Management:
- Correct the cause – glasses
- Occlusion therapy to prevent amblyopia (patching of good eye => strengthens muscles of weaker)
- Surgical correction
Types of Strabismus?
Complications of Strabismus in Children and Adults?
Children can unconsciously suppress the image from one misaligned eye to avoid seeing double => may lead to Amblyopia and Permanent Visual Loss
Adults develop Strabismus as a result of Trauma or a Cranial Nerve Palsy
can’t suppress the image from a misaligned eye => Diplopia (Double Vision)
Causes/Treatments of Amblyopia?
Causes if uncorrected (interferes w/ normal cortical visual development):
- Refractive Error (Hyperopia/Myopia)
- Anisometropia: Difference in refractive error between 2 eyes
- Strabismus (Squint)
- Congenital cataracts
Treatment (Treatable until ~ Age 8):
- Occlusion Therapy (patching of good eye => strengthens muscles of weaker)
- Atropine (relax the focusing muscles of the eye, which blurs vision in the good eye during the treatment)
What is the Shaken Baby Syndrome Triad?
Brain Edema:
Intracranial Hemorrhages
Retinal Hemorraghes + Retinoschisis(Splitting in retinal layers VERY Suspicious for abuse)
What can cause abnormalities with the Red Reflex in Infants?
Leukocoria (White Pupil): Diminished red reflex due to obstruction of normal retina
Causes:
- Congenital Cataracts
- Retinopathy of Prematurity (ROP)
- Retinoblastoma (Tumour at back of the Eye)
