(PM3A) Ocular Procedures + Formulations

Question 1

What is cataract surgery?

Answer 1

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

Question 2

What is an intraocular lens (IOL)?

Answer 2

An artificial lens for the eye

Question 3

What were intraocular lenses first made of?

Answer 3

PMMA

Question 4

What are intraocular lenses now made of?

Answer 4

Soft polymers

Based on silicon/ acrylic polymers

Question 5

Why were PMMA intraocular lenses replaced with those made with soft polymers?

Answer 5

(1) PMMA is rigid

(2) PMMA required a 7mm incision

(3) Soft polymers can be folded

(4) Soft polymers only require a 3mm incision

Question 6

Name some potential risks of cataract surgery.

Answer 6

(1) Infection

(2) Postoperative inflammation

(3) Posterior capsule opacification

(4) Secondary cataracts causes by epithelial cell adhesion + proliferation in posterior lens capsule

Question 7

How may some of the potential risks of cataract surgery be solved?

Answer 7

Drug-eluting intraocular lenses

Allow for postoperative delivery of ABx and anti-inflammatory medication

Question 8

What are ocular bandages?

Answer 8

Provide protective hydrogel film barrier

Stabilises ocular wounds

Promotes healing by protecting corneal incision from eyelid trauma

e.g. OcuSeal Liquid Ocular Bandage

Question 9

What is keratoconus?

Answer 9

Ocular degenerative condition

Affects cornea, weakens + thins

Causes irregular shape

High levels of astigmatism (distortion) + blurred vision

Question 10

What is corneal cross-linking?

Answer 10

(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

Question 11

What is the purpose of using UV-A light in corneal cross-linking?

Answer 11

(1) UV-A light radiation activates riboflavin

(2) Generates reactive oxygen

(3) Induces covalent bonds between collagen fibrils in corneal stroma

Question 12

What are some of the excipients of Ricrolin TE?

Answer 12

• Basic Riboflavin
• Dextrane T500
• Edetate sodium
• Tromethamine
• Bihydrate sodium phosphate monobasic
• Bihydrate sodium phosphate bibasic
• Purified water

Question 13

What is laser eye surgery?

Answer 13

LASIK - laser in situ keratectomy

Performed by an ophthalmologist

Uses a laser/ microkeratome

Reshaping cornea to improve visual ability

Question 14

What is the purpose of LASIK surgery?

Answer 14

Reshape the cornea

Provides a permanent alternative to glasses/ contact lenses

Flattens cornea for near-sighted

Steepens cornea for far-sighted

Question 15

How does LASIK surgery treat far-sighted patients?

Answer 15

Steepens the cornea

Question 16

How does LASIK surgery treat near-sighted patients?

Answer 16

Flattens the cornea

Question 17

What is astigmatism?

Answer 17

Defect in the eye or in a lens caused by a deviation from spherical curvature

Results in image distortion

Question 18

How does LASIK surgery treat astigmatism?

Answer 18

Shapes irregular cornea into a more normal shape

Question 19

What is the process of LASIK surgery?

Answer 19

(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

Question 20

Why are stitches not required following LASIK surgery?

Answer 20

Corneal flap sticks to corneal tissue in 2-5 minutes

Question 21

What are some of the risks of LASIK surgery?

Answer 21

(1) Infection

(2) Inflammation

(3) Small chance that vision will be worse after surgery

Question 22

What are some side effects of LASIK surgery?

Answer 22

(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)

Question 23

What type of eye drops are commonly used prior to ocular surgery?

Answer 23

Povidone-Iodine 5% eyedrops
- Broad-spectrum antiseptic activities

Question 24

What is the post-operation treatment following ocular surgery?

Answer 24

Ketorolac trometamol 5mg/mL (NSAIDs)

Called Acular

Question 25

What is Acular?

Answer 25

Post-operative treatment following ocular surgery

Ketorolac trometamol

Question 26

What post-operation antibiotics are given following ocular surgery?

Answer 26

(1) Azyter eye drops - azithromycin

(2) Azasite ophthalmic solution 1% - azithromycin

Question 27

When is azithromycin given?

Answer 27

Following ocular surgery

Antibiotic to prevent infection

Question 28

Give an example of a penetration enhancer that could be used in the eye, for corneal cross-linking.

Answer 28

(1) Cyclodextrins

(2) Chelating agents

Question 29

Why is the epithelium removed in corneal cross-linking surgery?

Answer 29

Corneal epithelium acts as a barrier to riboflavin

Question 30

What is Ricrolin TE?

Answer 30

A potential alternative to riboflavin

Potentially does not require removal of corneal epithelium for corneal cross-linking