Monday, January 23
Last blogged @ 14:34

Vitamins
-essential for healthy growth and development
-cannot be synthesized by an organism
-obtained from diet
Vitamin Deficiency
-due to socioeconomic status and/or nutritional deficiency
-manifests into systemic, psychological or ocular disease(s)

Vitamin A
-essential to maintain mucus membranes, skin and vision
Vitamin A Deficiency
-Xeropthalmia
-night blindness
-Bitot's spots(foamy grey, traingular spots of keratinised epithelium on the conjunctiva)
-conjunctival Xerosis (abnormal dryness of the conjunctiva)
-corneal Xerosis (abnormal dryness of the cornea)
-keratomalacia (softening and necrosis (morphological changes indicative of cell death due to the progression of enzymatic degradation) of the cornea)
-blindness

Cotton Wool Spots (CWS)
-accumulation of mitochondria and ruptured cells within areas of swollen nerve fibre layers
-caused by vascular disease that stop/reduce axoplasmic transport
-sign of ischemia (insufficient blood supply) or microinfarct (mini localised area of ischemic necrosis produced by occlusion of arterial supply or venous drainage at the part)
-reabsorbs over 6-8 weeks
-leaves groove defect in nerve fibre layer
-arcuate visual fiel defect

Hard Exudates
-lipid and lipoprotein deposition between functional and diseased retina
-due to increased vascular permeability
-seen as well-defined waxy, shiny areas in outer plexiform layer
-can be little dots, circinate (circular or ring-like) or macular star

Retinal Oedema
Superficial
-seen as diffuse haze at nerve fibre layer
-common at optic nerve head and posterior pole
-occurs in hypertension and/or papilloedema
Deep
-seen as dense haze at the outer plexiform layer
-common at macular and posterior pole
-occurs in post-cataract surgery and/or diabetes
Cloudy
-seen as white/opaque
-due to arterial occlusion adn ischemia

Retinal Haemorrhages
Pre-retinal Haemorrhage
-posterior to the inner limiting membrane
-obscures the retinal blood vessels
-can be in patches or boat-shaped/D-shaped
-may or may not be due to ocular disease
Flame-shaped Haemorrhage
-within the nerve fibre layer
-follows the structure of ganglion cell fibres
-associated with vascular disease affecting sperficial and peripapillary capillary beds
-Roth's sots
-flame-shaped haemorrhages with white/pale centre
-associated with systemic inflammation
Dot-blot Haemorrhage
-between inner limiting membrane and outer plexiform layer or middle retina
-appears as round dots as it follows the divergence of axons
-takes a longer time to resolve as compared to superficial haemorrhage
Sub-retinal Haemorrhage
Sub-RPE Haemorrhage
Vitreous Haemorrhage