fundamentals of veterinary opthalmology

Question 1

list the 3 types of therapeutic formulation types for topical eye treatment?

Answer 1

1. solution
2. suspension
3. ointments

Question 2

list the properties of solutions?

Answer 2

PH 3.5-10.5
must be stored in fridge
must be sterile

Question 3

describe suspension topical treatments?

Answer 3

the drug is formulated into small particles that are dissolved by the tears for absorption
Prolonged contact time

Question 4

describe ointment topical treatment properties?

Answer 4

Oil or water based

oil based ointments can inhibit corneal wound healing

Question 5

describe the absorption of lipid soluble drugs?

Answer 5

easy, transcellular absorption

Question 6

describe the absorption of water soluble drugs?

Answer 6

Poor, intercellular absorption

Question 7

how does EDTA treatment alter the corneal surface?

Answer 7

widens the intracellular space between the cells by helping the penetration of water-soluble drugs

Question 8

name the drug delivery systems for prolonged therapy?

Answer 8

1. soft contact lenses - can last >24 hrs
2. absorbable or non-absorbable implants, can last >weeks
3. micro pumps

Question 9

list the advantages of sub conjunctival injections?

Answer 9

cornea-conjunctival barrier is bypassed

high drug concentration at the anterior segment

Question 10

name the main drug types administered via sub conjunctival injection route?

Answer 10

mydriatics, antibiotics, corticosteroids

Question 11

what is retrobulbar injection used for?

Answer 11

introduction of drugs into the orbital cavity

–> high drug concentratuon in the orbit and the posterior segment

Question 12

describe a contraindication of retrobulbar injection?

Answer 12

IOP may increase after administration

Question 13

describe the indication of intravitreal injections?

Answer 13

penetration into the vitreous is poor (due to blood -aqueous retina barriers)
so its a direct application to the area

Question 14

what is the main use for vitreous injections?

Answer 14

administration of ABs under general anaesthesia

Question 15

describe why systemic drug applications aren’t always effective?

Answer 15

diffusion of drugs present in the systemic circulation to the anterior and posterior segments are curtailed by the blood-aqueous and blood retinal barriers respectively