common conditions of the eye

Question 1

where do optic vesicles grow?

Answer 1

outwards from diencephalic part of neural tube towards surface ectoderm.

Question 2

whaat is conjunctivitis?

Answer 2

Self-limiting bacterial or viral infection of the conjunctiva.

Question 3

symptoms of conjunctivitis?

Answer 3

Red, watering eyes, discharge +. No loss of vision as long as infection does not spread to cornea

Question 4

treatment of conjunctivitis?

Answer 4

antibiotic eye drops if likely to be bacterial

Question 5

what is a stye thats external called?

Answer 5

hordeolum externum

Question 6

what is a stye that is internal called?

Answer 6

hordeolum internum

Question 7

what is the treatment of styes?

Answer 7

warm compress, eyelid hygiene, may need surgical incision and curettage

Question 8

wht is the histology of the cornea?

Answer 8

Epithelium – stratified squamous non-keratinised.

Bowman’s membrane (basement membrane of corneal epithelium)

Stroma – regularly arranged collagen, no blood vessels

Descemet’s layer
Endothelium – single layer (normal - 2500 cells/mm2)

Question 9

whats the pathology of the cornea?

Answer 9

Inflammatory – eg: corneal ulcers

Non-inflammatory – eg: dystrophies
Corneal pathologies frequently lead to opacification of the cornea. This might need to be treated by corneal transplant - Keratoplasty

Question 10

psthology of a corneal ulcer

Answer 10

Infectious - Viral/ bacterial/ fungal infection of cornea. Needs aggressive management to prevent spread, scarring.

Non-infectious ulcers due to trauma, corneal degenerations or dystrophy.

Question 11

what are corneal dystrophies?

Answer 11

a group of genetic, often progressive, eye disorders in which abnormal material often accumulates in the clear

Question 12

what are the different types of corneal dystrophies?

Answer 12

Bilateral 
Opacifying
Non – inflammatory
Mostly genetically determined.
Sometimes due to accumulation of substances such as lipids within the cornea

Question 13

what is the significance of the avascularity of the cornea?

Answer 13

benefit to surgeons when performing a graft surgery as it means there is a lesser chance of foreign antigens from a corneal graft being recognised by the recipient, so lesser chance of a graft rejection.

Question 14

is there any lymphatics draining in the eyes/eyelids?

Answer 14

no

Question 15

what are some common disease cinditions of the eye?

Answer 15

cataract
glaucoma
age-related macular degeneration
diabetic retinopathy
corneal opacities
childhood blindness
trachoma

Question 16

why do cataracts develop?

Answer 16

Older (embryological, foetal) fibres are never shed – compacted in the middle

No blood supply to lens, which depends entirely on diffusion for nutrition

Absorbs harmful UV rays preventing them from damaging retina but in the process, get damaged themselves

Damaged lens fibres–> opaque —>CATARACT

Question 17

what is the management of cataracts?

Answer 17

Eye drops do not treat cataract!

Surgery – (day case) small incision lens capsule opened cataractous lens removed by emulsification (phacoemulsification) plastic lens placed in capsular bag

Lens implant after cataract surgery – PCIOL = Posterior Chamber Intra Ocular Lens

Question 18

what is the 2nd most common global cause of blindness?

Answer 18

glaucoma

Question 19

what is the most commonly seen from of primary glaucoma?

Answer 19

primary open angle glaucoma

Question 20

what is the consequence of raised intraocular pressure

Answer 20

Pressure on nerve fibres on surface of retina–> die out —> visual field defects

Question 21

what is the triad signs of glaucoma?

Answer 21

raised IOP
visual field defect
optic disc changes on ophthalmoscopy

Question 22

whats the management of POAG?

Answer 22

Eye drops to decrease IOP
Prostaglandin analogues
Beta-blockers
Carbonic anhydrase inhibitors

Laser trabeculoplasty

Trabeculectomy surgery

Question 23

what is angle closure glaucoma?

Answer 23

Sudden onset, painful, vision lost/ blurred; headaches (often confused with migraine)

Question 24

signs of angle closure glaucoma?

Answer 24

Red eye, cornea often opaque as raised IOP drives fluid into cornea
AC shallow, and angle is closed.
Pupil mid-dilated
IOP severely raised
Right eye: red and inflammed, cornea hazy, pupil mid-dilated

Question 25

what are the mechanisms for the angle closing?

Answer 25

Functional block in a small eye – large lens
Mid-dilated pupil periphery of iris crowds around angle and outflow is obstructed
Iris sticks to pupillary border (synechia) which prevents reaching AC. Leads to iris balooning anteriorly and obstructing angle.

Question 26

whats the management of an acute episode?

Answer 26

Decrease IOP
IV infusion with or without oral therapy – carbonic anhydrase inhibitors (acetazolamide)
Analgesics, antiemetics
Constrictor eye drops – pilocarpine
If no contraindication beta-blocker drops such as timolol
Steroid eye drops (dexamethasone)

Iridotomy (laser) - both eyes - to bypass blockage

Question 27

whats the difference between open angle and angle closure glaucoma?

Answer 27

In open angle glaucoma the drainage through the trabecular meshwork is blocked (in most cases)
This leads to a gradual, painless build up of intraocular pressure (IOP).
This type of Glaucoma is called Primary Open Angle Glaucoma (POAG)

In angle closure glaucoma, some event on a predisposed eye leads to the peripheral iris blocking the angle, therefore aqueous can’t drain.
So the increase in IOP is sudden leading to a red eye, and severe pain.
Patient usually presents as an emergency

Question 28

what is uveitis?

Answer 28

inflammation of uvea

Question 29

what are the different types of uveitis?

Answer 29

Anterior uveitis – iris with or without ciliary body inflammed

Intermediate uveitis – ciliary body inflammed

Posterior uveitis – choroid inflammed

Question 30

causes of uveitis?

Answer 30

Isolated illness
Non-infectious autoimmune causes – eg: presence of HLA-B27 predisposes to anterior uveitis
Infectious causes – chronic diseases such as TB
Associated with systemic diseases – eg: ankylosing spondylosis

Question 31

whats the pathophysiology of anterior uveitis?

Answer 31

An inflammed anterior uvea (iris) leaks plasma and white blood cells into the aqueous humor

These are seen during slit lamp examination as a hazy anterior chamber and cells deposited at the back of the cornea

The eye is red, painful, with visual loss

Cells in the AC may settle inferiorly – “hypopyon”

Question 32

pathology of intermediate uveitis

Answer 32

In intermediate uveitis the ciliary body is inflammed and leaks cells and proteins.
This leads to a hazy vitreous
Patient complains of “floaters” or hazy vision

Question 33

pathology of posterior uveitis

Answer 33

In posterior uveitis the choroid is inflammed.

Since the choroid sits under the retina, the inflammation frequently spreads to the retina causing blurred vision