Fundamentals of Veterinary Ophthalmology Flashcards

1
Q

Give the formulation categories of drugs used in ophthalmology

A
  1. Topical drugs
  2. Injectable drugs
  3. Oral drugs
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2
Q

Give the topical formulations used in eyes

A
  1. Solution
  2. Suspension
  3. Ointment
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3
Q

Summarise topical eye solutions

A
  • pH = 3.5 → 10.5
  • Sterile

pH + temperature = stability

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4
Q

Summarise topical eye suspensions

A
  • Drug is included in small particles
  • Tear dissolves these particles → Absorbed as a solution

This leads to a prolonged contact time

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5
Q

Summarise topical eye ointments

A
  • Oil/water based
  • Inhibition of corneal wound healing

pH & temp. is not so important in the stability

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6
Q

Give the application methods for topical eye therapy

A
  1. Dropping
  2. Ointmenting
  3. Subpalpebral methods
  4. Nasolacrimal methods
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7
Q

Give the application methods for injectable eye therapy

A
  1. Subconjunctival injection
  2. Retrobulbar injection
  3. Intravitreal injection
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8
Q

Give the application methods for systemic eye therapy

A
  1. IV & IM injection
  2. IV infusion
  3. PO administration
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9
Q

Summarise dropping as a method of topical eye therapy

A
  • Easily controlled dosage
  • Quick elimination from the eye by tears
  • Prevention of contamination by the container
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10
Q

Summarise ointments as a method of topical eye therapy

A
  • Less drug elimination than the dropping method
  • Application may be achieved with a finger
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11
Q

Summarise subpalpebral & nasolacrimal methods for topical eye therapy

  • Give indications for their use
A

Continuous/intermittent topical lavage may be achieved

Indications:

  1. Painful ocular conditions
  2. Tarsorrhaphy (when eyelids are sewn together)
  3. Long-term therapy
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12
Q

Give the fate of topical medication after it has been applied

A

Either:

  1. Washed out
  2. Absorbed by the conjunctival capillaries
  3. Penetration to the cornea
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13
Q

Absorption of lipid-soluble drugs

A
  • Easy absorption
  • Transcellular absorption

Therefore lipid-soluble would be your drug of choice

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14
Q

Absorption of water-soluble drugs

A
  • Poor absorption
  • Intercellular absorption
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15
Q

Higher/prolonged drug concentration may be achieved by…

A
  • ↑ Frequency of treatment
  • Improving the composition of the formulation
  • Alter the corneal surface
  • Use of drug delivery systems
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16
Q

Examples of drug delivery systems in the eye

A
  • Soft contact lenses
  • Absorbable/non-absorbable implants
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17
Q

Summarise the subconjunctival injection

A
  • Bypass of the cornea-conjunctiva barrier
  • ↑ Drug concentration in the anterior segment
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18
Q

Which drugs would be applied using the subconjunctival injection method?

A
  • Mydriatics
  • Antibiotics
  • Corticosteroids
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19
Q

Summarise the retrobulbar injection

A
  • ↑ Drug concentration in the orbit & posterior segment
  • The animal must be anaesthetised
  • Lower-lateral quadrant into the retrobulbar space
  • Injection may lead to an ↑ of IOP
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20
Q

Which drugs may be used for retrobulbar injection?

A
  • Small animal: Antibiotics & local anaesthetic
  • Cow: Local anaesthetic for exstirpation (eye removal)
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21
Q

Summarise the intravireal injection

A
  • Penetration of drugs into the vitreous humor is poor
  • This must be performed under general anaesthesia
  • Lateral canthus, 2-3mm from the limbus
  • Remember to aspirate before injecting

Rarely performed

22
Q

Which drugs may be given by intravitreal injection

A

Antibiotics

23
Q

Which systemic drugs may given by IV/IM injection for the eye?

A
  • Antibiotics
  • Anti-inflammatories
24
Q

Which systemic drugs may given by IV infusion for the eye?

A

Hyperosmotics

25
Q

Which systemic drugs may given Per Os for the eye?

A
  • Antibiotics
  • Anti-inflammatories
  • Hyperosmotics
26
Q

Route of administration for lesions in the: Cornea or Conjunctiva

A
  • Topical application
  • Subconjunctival injection
27
Q

Route of administration for lesions in the: Anterior uveal tract

A
  • Subconjunctival injection
  • Systemic application
28
Q

Route of administration for lesions in the: Posterior uvea

A
  • Retrobulbar injection
  • Systemic application
29
Q

Route of administration for lesions in the: Vitreous humor

A
  • Intravitreal injection
  • (Systemic application)
30
Q

Which sympathetic sites may autonomic drugs be used for in the eye?

A
  • m. dilator pupillae
  • glandula lacrimalis
31
Q

Which parasympathetic sites may autonomic drugs be used for in the eye?

A
  • m. sphincter pupillae
  • m. cilicaris
  • glandula lacrimalis
32
Q

List the physiological functions of autonomic drugs in the eye

A
  1. Mydriasis
  2. Miosis
  3. Cycloplegia
  4. Cyclospasm
33
Q

Define: Mydriasis

A

Dilation of the pupil

34
Q

Define: Miosis

A

Constriction of the pupil

35
Q

Define: Cycloplegia

A

Relaxation of the ciliary muscle

36
Q

Define: Cyclospasm

A

Constriction of the ciliary muscle

37
Q

Function of parasympatholytics in the eye

A
  1. Blocking of the m. sphincter pupillae & ​m. ciliaris
  2. Mydriasis with cycloplegia
38
Q

List the parasympatholytics used in the eye

A
  • Atropine
  • Tropicamide
  • Homatropine
  • Cyclopentolate
39
Q

Summarise atropine as an ophthalmic drug

A
  • Strong cycloplegic
  • Strong mydriatic in pre- & post-operative therapy
  • May ↑ IOP & induce salivation

Not to be used as a diagnostic mydriatic

40
Q

Summarise tropicamide as an ophthalmic drug

A
  • Fast-acting, effective mydriatic
  • Poor cycloplegic
  • Ideal for inducing diagnostic mydriasis
  • Ø Side effects
41
Q

Function of parasympathomimetics in the eye

A

Stimulation of m. sphincter pupillae & m. ciliaris

  1. Miosis & cyclospasm →
  2. ↑ Outflow →
  3. ↓ IOP
42
Q

List the parasympathomimetics used in the eye

A
  • Pilocarpine
  • Carbachol
  • Echothiophat
  • Demecarium
  • Isoflurophate
43
Q

Summarise pilocarpine as an ophthalmic drug

A
  • Used for the therapy of ↑ IOP & dry eye syndrome
  • Sometimes may have side effects
  • Formulised as a solution or gel
44
Q

Function of sympatholytics in the eye

A

Blocking of m. dilator pupillae function

  • Miosis
45
Q

List the sympatholytics used in the eye

A
  • Timolol
  • Betaxolol
46
Q

Summarise timolol & betaxolol as ophthalmic drugs

A
  • Used in the treatment of ↑ IOP

Note that this is not as a result of the miosis

47
Q

Function of the sympathomimetics in the eye

A

Stimulation of the m. dilator pupillae & smooth muscles of the vessels

  • Mydriasis
  • Vasoconstriction
48
Q

List the sympathomimetics used in the eye

A
  • Phenylephrine
  • Adrenaline
49
Q

Summarise phenylephrine as an ophthalmic drug

A
  • Used for induction of pre- & post-operative mydriasis
  • Additive effect with parasympatholytics
50
Q

Summarise adrenaline as an ophthalmic drug

A
  • Ineffective mydriasis: Penetrates the eye and is quickly destroyed
  • Solution for injection: Relieves mild haemorrhage