Opthalomology Flashcards
(66 cards)
What is amblyopia ?
Neurodevelopmental visual disorder with unilateral (less commonly bilateral) reduction of visual acuity
COMMON IN CHILDREN
What is amblyopia most commonly caused by?
strabismus
What is strabismus?
Eye alignment problems - ocular misalignment in one or BOTH the eyes
What are the 6 types of strabismus?
what are the two overall classes of strabismus ?
Heterotropia - deviation apparent if patient using both eyes (esotropia if crossed eye) and Exotropia if wall eyed) Hypertropia (upwards) Hypotropia (downwards)
Accomadative esotropia (eyes turned inward due to the effort of trying to accomadate to focus far sighted eyes Pseudostrabismus (appearance of esotropia due to prominant epicanthal folds esp. asians
Paralytic and Non paralytic:
Concomitant strabimus = Non Paralytic
deviation same no matter gaze position
Usually congenital or child onset due to sensory depreviation
Incomitant strabismus = Paralytic
Usually Nerve Palsy or Extra Ocular muscular disease (3,4 and 6th nerve palsy
Deviation varies when parient shifts gaze.
Heterophoria (latent deviation)
Deviation apparent when patient is using ONE eye deviation established by cover test (i.e. deviated when using one eye)
What is diagnosis assessment for strabismus (2)
Hirschberg test (corneal light reflex)
Cover test (assessing for deviation)
What is Hirschberg test ?
test for ocular alignment. Also known as corneal light reflex test.
how to perfrom hirschprings test
Use a light source, such as a penlight or finhoff transilluminator.
Instruct the patient to focus their gaze on your light source.
From a distance of 2 feet, shine your light source equally into the patient’s eyes at midline.
Observe the reflection of light off the cornea, which should appear as a pin-point white light near the center of the pupil in each eye.
In Esotropia (inward deviation) light source is displaced outwardly.
In Exotropia (outward deviation) light source displaced inwardly
In Hypertropia (upward deviation) light source is displaced down
In hypotropia(downward deviaiton) (light source is displaced up)
How to perform cover test –>
it is used to determine if a phoria (i.e. latent strabismus) is present.
- examiner occludes one eye for 1-2 seconds, then removes it. The eye that was previously occluded in observed (the one being tested for Heterophoria) for refixation movement (striaght looking) to re-establish sensory fusion with other eye.
What do you do with child who is diagnosed with strabismus?
PROMPT referral to opthalmologist, treatment may include :
glasses (for accomadative esotropia)
Opthalmic surgery
Accomodative Esotropia : What is this ?
Important to determine between long sightedness and whether they have a strabismus.
if a child islong sightedand needs to accommodate to see better, this can cause their eyes to turn in too much towards one another and they may go on to develop a convergentsquint(esotropia). Having glasses to correct theirlong sightednessallows their focusing to relax and give clearer vision
What is a refractive error? What are the 4 most common types?
Shape of lens does not bend light correctly, resulting in a blurred image. Main types of refractive errors are myopia, hyperopia, presbyopia and astigmatism
What is used to test for a refractive error?
Pin Hole Test
What will the pin hole show with refractive errors?
If reduced vision is caused by refractive error, a pinhole will cause improvement in visual acuity.
Vitreous what is it ?
The vitreous is the gel-like fluid that fills your eye. It’s full of tiny fibers that attach to your retina (the light-sensitive layer of tissue at the back of the eye)
Macula: What is it ?
macula is about 5mm across, and is part of the retina. Reponsible for main central vision, most of colour vision and fine details, with high concentration of photoreceptor cells - cells that see light
how often do diabetics get retinal screen ?
Two yearly (can be increased frequency)
What is the 5 main reasons diabetics cannot see?
- Blood sugar leading to osmotic effect changing shape of their lens = causing a refractive error
2nd commonest: Cataracts (over time)
RETINOPATHYS
3rd= Vitreous Hamorrhage (suddenly)
4th Macular Degeneration/blockage of retinal artery/vein
5th Optic nerve disease/Ischaemia of optic nerve
Diabetic Retinopathys: What are the 4 types?
- Background Retinopathy
- Diabetic Maculopathy
- Proliferative and Pre-proliferative
diabetic retinopathy - Advanced diabetic eye disease
Background retinopathy : What is this ?
commonest set of changes that reflect anatomical changes to vessels. Vision is usually normal
What is treatment for background retinopathy?
generally no ocular management
However when will background retinopathy need treatment ?
Unexplained decrease in visual acuity.
If not improved by pinhole (which would indicate a refractive error) refer as may be macula oedema
Rapid progression of background changes refer
Hard exudates close to the macula (refer)
Background Retinopathy 4 things that occur:
What does vision tend to be like?
Micro-anuerysms
haemorrhages
Hard exudates
Retinal oedema
Vision tends to be normal
Which of the 4 background retinopathy tends to cause symptoms and what should you do ?
Fluid leakage causing oedema that causes retinal dysfunction. Patients will only have symptoms if it tends to affect the macula and they will present with poor visual acuity that is not improved by pinhole test. REFER