Visual systems + optometry

Question 1

Visual system: Adnexa- eyelids

Answer 1

• Protect eye
• Assist tear distribution and drainage
• Glands contribute to tear film

Question 2

Visual system: Adnexa -the conjunctiva

Answer 2

• lubricates & nourishes eye surface
• glands contribute to tear film

Question 3

Visual system: Adnexa –lacrimal apparatus

Answer 3

• contributes to tear
• productiontear drainage

Question 4

Visual system: Adnexa –extraocular muscles

Answer 4

• eye movements
• four recti
• two obliques
• Squint = weakness of these muscles, give botox injection to correct this

Question 5

Visual system: Eye -layers -outer

Answer 5

• cornea
  
  • main refractive component
• limbus
  
  • aqueous humour drainage
• sclera
  
  • protects & supports eyeball

Question 6

Visual system: Eye- layers middle

Answer 6

• Vascular layer (Uveal tract)
  
  • Iris
    
    • Controls amount of light entering the eye
    • Sphincter and dilator pupilae
  • Cilliary body
    
    • Accomodation
    • Cilliary muscle
    • Aqueous humour production
  • Choroid
    
    • Nurishes retina
    • Absorbs stray light

Question 7

Visual systems: Eye- layers inner

Answer 7

• Retina
  
  • Light detected by
    
    • RODS predominate in the periphery (detection)
    • CONES predominant in the fovea (identification)- high resolution and allow colour
  • Signals pass to BIPOLAR and GANGLION cells
  • Signals modified by horizontal and amacrine cells

Question 8

Visual systems: Eye- media

Answer 8

• Aqueous humour
  
  • Transparent fluid
  • Nurishes cornea and lens
  • Itraocular pressure
• Crystaline lens
  
  • Variable refractive component (Accommodation)
• Vitreous body
  
  • Mechanically supports crystalline lens and retina

Question 9

Visual systems: Brain- visual pathway

Answer 9

• Optic nerve
• Chiasm
• Optic tract
• Lateral geniculate nucleus
• Optic radiation
• Visual cortex

Question 10

Optometry: Refraction

Answer 10

• Myopia, hyperopia, astigmatism
• Presbyopia
• Myopia= short sight, the focus of the light is in front of the lens
• Hyperopia= long-sighted, focus behind the lens
• Astigmatism= 2 different points of focus on the lens due to rugby ball lens

Question 11

Optometry: Anterior eye disease

Answer 11

• External examination
  
  • Eyelid conjunctiva, cornea sclera, iris
• Pathology
  
  • E.g. blepharitis (dandruff of the eyelids), conjunctivitis, keratitis (corneal ulcers), scleritis, neoplasia

Question 12

Optometry: posterior eye disease

Answer 12

• Internal examination
  
  • Media, retina, optic nerve
• Pathology
  
  • Cataracts, uveitis, retinopathy, maculopathy, optic neuropathy, neoplasia

Question 13

Optometry: brain disease

Answer 13

• Perimetry
  
  • Visual pathway
• Pupil light reflexes
  
  • Midbrain
• Cover test, motility
  
  • Brain stem

Question 14

Autonomic nerves, diagnostic drugs & the eye

Answer 14

• sympathomimetics
  
  • dilator pupillae stimulated (mydriasis)
• sympatholytics
  
  • dilator pupillae blocked (miosis)
• parasympathomimetics sphincter pupillae & ciliary muscle stimulated (miosis & accommodative spasm)
• anti-muscarinic
  
  • receptors on sphincter pupillae and ciliary muscle blocked (mydriasis & cycloplegia)
• NB –topical anaesthetics also used for diagnostic purposes

Question 15

Therapeutic drugs that optometrists may prescribe

Answer 15

Question 16

Signed orders

Answer 16