Vascular Tunic: Iris, Ciliary Body, Choroid Flashcards

Question

What is the pathophysiology for glaucoma?

Answer 1

2 theories 1. Drain blocks at iridocorneal angle * Aqueous humour produced by ciliary body can’t drain out through trabecular mesh work into Schlemm’s canal and hence pressure builds up * Patients' eyesight gradually declines with loss of peripheral visual fields * Pressure is not always raised - some patients may develop normal pressure glaucoma (optic nerve damage without raised intraocular pressure) 2. Poor blood supply to optic nerve

Answer 2

* More likely to be a _chronic_ condition, more common than closed angle. Patients often asymptomatic for a long time as they do not notice the losses to their peripheral vision in early disease * Usually only present once severe, irreversible damage has occurred - up to 90% of the optic nerve fibres may have been damaged * Aqueous fluid does not drain well out of the eye, increasing the pressure in the eye. It is thought that the trabecular meshwork becomes blocked, preventing this drainage

Answer 3

* RAPD on swinging flashlight test due to optic nerve damage * Hardness of the eyeball on palpation due to raised IOP * Slit lamp: may show corneal oedema, change in pupil shape and iris atrophy * IOP \>21mmHg (better to not spend too much time investigating)

Answer 4

Classified based on : * Whether the peripheral iris is covering the trabecular meshwork, which is important in the drainage of aqueous humour from the anterior chamber of the eye. * In open-angle glaucoma, the iris is clear of the meshwork. The trabecular network functionally offers an increased resistance to aqueous outflow, causing increased IOP. It is now recognised that a minority of patients with raised IOP do not have glaucoma and vice versa.

Answer 5

* Hyphema is blood in the anterior chamber of the eye * In context of trauma, referral to opthalmic specialist for assessment and management. * Main risk to sight comes from raised intraocular pressure developing from blockage of angle and trabecular meshwork with eythrocytes. * Strict bed rest required as excessive movement can redisperse blood that had previously settled therefore high risk cases are often admitted * Isolated hyphema will also require dailly opthalmic review and pressure check initially as an outpatient.

Answer 6

* Miosis (small pupil) * Ptosis * Enophthalmos\* (sunken eye) * Anhidrosis (loss of sweating one side)

Answer 7

Central Lesions * Anhidrosis of the face, arm and trunk Pre-ganglionic Lesions * Anhidrosis of the face Post-ganglionic Lesions * No anhidrosis

Answer 8

Damage to the sympathetic trunk * **Central Lesions** * Stroke * Syringomyelia * Multiple sclerosis * Tumour * Encephalitis * **Pre-Ganglionic Lesions** * Pancoast's tumour * Thyroidectomy * Trauma * Cervical rib * **Post-Ganglionic Lesions** * Carotid artery dissection * Carotid aneurysm * Cavernous sinus thrombosis * Cluster headache

Answer 9

**Heterochromia (difference in iris colour)** is seen in congenital Horner's

Answer 10

* Common eye condition where the lens of the eye gradually opacifies i.e. becomes cloudy. This cloudiness makes it more difficult for light to reach the back of the eye (retina), thus causing reduced/blurred vision. * Cataracts are the leading cause of curable blindness worldwide. * Cataracts are more common in women than in men * The incidence of cataracts increases with age. One study found that 30% of individuals aged 65 and over had a visually-impairing cataract in either one or both eyes

Answer 11

* Normal Ageing process is most common * Smoking * Increased alcohol consumption * Trauma * Diabetes mellitus * Long-term corticosteroids * Radiation exposure * Myotonic dystrophy * Metabolic disorders: hypocalcaemia

Answer 12

* Reduced vision * Faded colour vision: making it more difficult to distinguish different colours * Glare: lights appear brighter than usual * Halos around lights

Answer 13

**Defect in the red reflex** * Red reflex is essentially the reddish-orange reflection seen through an ophthalmoscope when a light is shone on the retina. Cataracts will prevent light from getting to the retina, hence you see a defect in the red reflex.

Answer 14

* **Ophthalmoscopy:** done after pupil dilation. * **Findings:** normal fundus and optic nerve * **Slit-lamp examination** * **Findings:** visible cataract

Answer 15

* **Nuclear:** change lens refractive index, common in old age * **Polar:** localized, commonly inherited, lie in the visual axis * **Subcapsular:** due to steroid use, just deep to the lens capsule, in the visual axis * **Dot opacities:** common in normal lenses, also seen in diabetes and myotonic dystrophy

Answer 16

* **Posterior capsule opacification:** thickening of the lens capsule * **Retinal detachment** * **Posterior capsule rupture** * **Endophthalmitis:** inflammation of aqueous and/or vitreous humour

Answer 17

In the early stages, age-related cataracts can be managed conservatively by * prescribing stronger glasses/contact lens, * encouraging the use of brighter lighting. These options help optimise vision but do not actually slow down the progression of cataracts, therefore surgery will eventually be needed.

Answer 18

* Surgery is the only effective treatment for cataracts which involves removing the cloudy lens and replacing this with an artificial one. * After cataract surgery, patients should be advised on the use of eye drops and eyewear, what to do if vision changes and the management of other ocular problems. * Cataract surgery has a high success rate with 85-90% of patients achieving 6/12 corrected vision (on a Snellen chart) postoperatively.

Answer 19

* NICE suggests that referral for surgery should be dependent upon whether a visual impairment is present, impact on quality of life, and patient choice. Also whether both eyes are affected and the possible risks and benefits of surgery should be taken into account. * Prior to cataract surgery, patients should be provided with information on the refractive implications of various types of intraocular lenses

Answer 20

* **Anterior Uveitis** describes inflammation of the anterior portion of the uvea - iris and ciliary body. * **Associated with HLA-B27** and may be seen in association with other **HLA-B27** linked conditions.