(PM3A) Ocular Procedures + Formulations Flashcards
What is cataract surgery?
Procedure to remove the lens of the patients eye
Replacement with artificial intraocular lens (IOL)
30-45 minutes under local anaesthetic, e.g. tetracaine hydrochloride 0.5% eye drops
What is an intraocular lens (IOL)?
An artificial lens for the eye
What were intraocular lenses first made of?
PMMA
What are intraocular lenses now made of?
Soft polymers
Based on silicon/ acrylic polymers
Why were PMMA intraocular lenses replaced with those made with soft polymers?
(1) PMMA is rigid
(2) PMMA required a 7mm incision
(3) Soft polymers can be folded
(4) Soft polymers only require a 3mm incision
Name some potential risks of cataract surgery.
(1) Infection
(2) Postoperative inflammation
(3) Posterior capsule opacification
(4) Secondary cataracts causes by epithelial cell adhesion + proliferation in posterior lens capsule
How may some of the potential risks of cataract surgery be solved?
Drug-eluting intraocular lenses
Allow for postoperative delivery of ABx and anti-inflammatory medication
What are ocular bandages?
Provide protective hydrogel film barrier
Stabilises ocular wounds
Promotes healing by protecting corneal incision from eyelid trauma
e.g. OcuSeal Liquid Ocular Bandage
What is keratoconus?
Ocular degenerative condition
Affects cornea, weakens + thins
Causes irregular shape
High levels of astigmatism (distortion) + blurred vision
What is corneal cross-linking?
(1) Removal of corneal epithelium (epithelial debridement)
ø 6-7mm diameter central zone
(2) Application of 0.1% riboflavin solution for 30 mins
(3) Irradiation with UV-A light at 370nm
What is the purpose of using UV-A light in corneal cross-linking?
(1) UV-A light radiation activates riboflavin
(2) Generates reactive oxygen
(3) Induces covalent bonds between collagen fibrils in corneal stroma
What are some of the excipients of Ricrolin TE?
- Basic Riboflavin
- Dextrane T500
- Edetate sodium
- Tromethamine
- Bihydrate sodium phosphate monobasic
- Bihydrate sodium phosphate bibasic
- Purified water
What is laser eye surgery?
LASIK - laser in situ keratectomy
Performed by an ophthalmologist
Uses a laser/ microkeratome
Reshaping cornea to improve visual ability
What is the purpose of LASIK surgery?
Reshape the cornea
Provides a permanent alternative to glasses/ contact lenses
Flattens cornea for near-sighted
Steepens cornea for far-sighted
How does LASIK surgery treat far-sighted patients?
Steepens the cornea
How does LASIK surgery treat near-sighted patients?
Flattens the cornea
What is astigmatism?
Defect in the eye or in a lens caused by a deviation from spherical curvature
Results in image distortion
How does LASIK surgery treat astigmatism?
Shapes irregular cornea into a more normal shape
What is the process of LASIK surgery?
(1) Eye is numbed with topical anaesthetic
(2) Eyelid holder placed between eyelids to keep open
(3) Suction ring placed on the eye (lifts + flattens cornea to stop it moving)
(4) Hinged flap of corneal tissue created using automated microsurgical laser/ blade
(5) Corneal flap lifted + folded back
(6) Excimer laser preprogrammed with patient’s specific eye measurements centred above eye
(7) Patient looks at fixation (target) light
(8) Excimer laser sculpts the corneal tissue
(9) Surgeon places flap back into position + smooths edges
(10) Stitches not needed as corneal tissue sticks to corneal flap in 2-5 mins
Why are stitches not required following LASIK surgery?
Corneal flap sticks to corneal tissue in 2-5 minutes
What are some of the risks of LASIK surgery?
(1) Infection
(2) Inflammation
(3) Small chance that vision will be worse after surgery
What are some side effects of LASIK surgery?
(1) Blurry vision
(2) Difficulty with night vision
(3) Dry eye
(4) Glare
(5) Halos/ starbursts around lights
(6) Light sensitivity
(7) Pain/ discomfort
(8) Pink/ red patches on sclera
SOME side effects may be permanent (not common)
What type of eye drops are commonly used prior to ocular surgery?
Povidone-Iodine 5% eyedrops
- Broad-spectrum antiseptic activities
What is the post-operation treatment following ocular surgery?
Ketorolac trometamol 5mg/mL (NSAIDs)
Called Acular
What is Acular?
Post-operative treatment following ocular surgery
Ketorolac trometamol
What post-operation antibiotics are given following ocular surgery?
(1) Azyter eye drops - azithromycin
(2) Azasite ophthalmic solution 1% - azithromycin
When is azithromycin given?
Following ocular surgery
Antibiotic to prevent infection
Give an example of a penetration enhancer that could be used in the eye, for corneal cross-linking.
(1) Cyclodextrins
(2) Chelating agents
Why is the epithelium removed in corneal cross-linking surgery?
Corneal epithelium acts as a barrier to riboflavin
What is Ricrolin TE?
A potential alternative to riboflavin
Potentially does not require removal of corneal epithelium for corneal cross-linking
