Cataract and Dry eyes Flashcards
C A T A R A C T
- Main cause of blindness
- Causes clouding of the eye lens that scatters or absorbs incoming light – results in visual impairment
- Develop as a result of electrolyte imbalance and low levels of glutathione
- Oxidative stress is a predisposing factor of cataract
- Crystallins are the main functional and structural protein of lens which become denatured and results in the cloudiness of the eye
T H E L E N S
- Bioconvex suspended in the anterior segment of the eye by suspensory ligaments
- The lens is highly transparent
- Avascular – no blood vessels
- Aqueous humour at the front of the eye and vitreous gel at the back of the eye supply the lens with nutrients
G L U T A T H I O N E
- Exists in high concentration in the lens
- Functions as essential antioxidant for maintenance of tissue’s transparency
- Low level of glutathione results in low levels of reactive oxygen species which affects the cell membrane of the lens epithelium
- Affects Na+/K+ pump
- Leads to increase in calcium which has the ability to cross link with negative charges and results in loss of ordered structure of chains
- Results in oedema – causes protein aggregation and cataract formation
C A T A R A C T T R E A T M E N T
- Surgery with lens extraction by emulsification and intraocular lens implantation through incision
- Drawbacks – invasive, costly and post-surgical complication
P O S T - O P E R A T I V E T R E A T M E N T
• Endophthalmitis which is inflammation in the two main liquids – aqueous humour and vitreous gel
- Can be prevented by the use of preoperative antiseptics
- Inject an antibiotic (intracameral cefuroxime) during cataract surgery to prevent
• Cystoid macular oedema which is part of the retina and affects a central part of vision
- Substances reach the macular during surgery and this produces an inflammatory response
- Could happen due to diabetes or trauma
- Can use NSAIDs drop, steroid drop, steroid and anti-infective agents
D R Y E Y E D I S E A S E
- Tear film has a important role is eye health and consists of four layers (lipid layer, aqueous layer, mucous layer and epithelial cells of the cornea)
- Dry eye disease is an irregularity in any of the glands related to tear production – there are three glands
- Lacrimal gland produces aqueous layer
- Meibomian gland produces lipid layer
- Goblet cells produce mucous layer
- It would affect both eyes, may be associated with mouth dryness, vision could clear when you blink due to spreading of tear fluid
T R E A T M E N T O F D E D
- Follow up 2-3 weeks after consultation
- Lifestyle advice
- Omega-3 supplements
F I R S T L I N E : H Y P E R M E L L O S E
- May need to be used up to 1-2 hours
* Ocular surface mucin is abnormal in tear deficient DE
C A R B O M E R S
- Has mucoadhesive properties
- Cling to the eye mucin
- Reduce application frequency – every 6 hours
P O L Y V I N Y L A L C O H O L
- Increases persistence of tear film
* Prolongs the duration of tear film before it gets washed out and new tear film is formed
S O D I U M C H L O R I D E 0 . 9 % W / V
• Used as comfort drops by contact lens wearers
E Y E O I N T M E N T S
- Containing paraffin lubricate the eye surface
- Preservative free options are expensive
- Liposomal sprays may be used but they are also expensive
OTHER
- Ciclosporin based eye drops are used for the treatment of severe DED
- Off label use of tacrolimus skin ointment can be used for meibomian gland inflammation
