Ophthalmology Flashcards
Emmetropia
Eye with no visual defects
Ametropia
Refractive error present/light rays not directly focused on retina
Myopia
Short sighted
- light rays brought to focus in front of retina
- eye is too long = axial myopia
- lens is too strong = index myopia
Hypermetropia
Long sighted
- light rays brought to focus behind retina –> eye is too short
OR converging power of cornea or lens is too weak
Astigmatism
Cornea is not spherical
Rugby ball NOT football
What is accommodation?
Physiological mechanism that allows close objects to be focused on the retina
- In non accommodative state - ciliary muscle relaxed allowing suspensory ligaments of lens to remain taut
- During accommodation - ciliary muscle contracts + suspensory ligaments become lax allowing lens to assume a convex shape
Entropion
In-turning of the lid, usually lower
- Causes = ageing, bacterial
- Tx = topical abx to prevent infection, tape down lower lid (temp), surgery
Ectropion
Eversion of lower lid
Causes = ageing, VII CN palsy
Tx = lubrication + surgery
Ptosis
Drooping of the eyelid
Blepharitis
Chronic inflammation of eyelid margins
Characteristics of Glaucoma
Optic disc cupping
Visual field loss
IOP is increased to impair normal optic nerve function
Types of Glaucoma
Primary open angle (POAG)
Primary acute angle closure
Secondary
Congenital
POAG syndrome
- Raised IOP >21
- Open aqueous draining angle e.g. no macroscopic blockage of aqueous outflow
- Pathologically cupped optic disc
- Glaucomatous visual field loss
Normal IOP
10-21mmHg
What is ocular HTN
Raised IOP >21 but normal optic disc + field
Causes of POAG
Ageing
Steroids (topical + systemic)
Inherited