DIS - Optic Nerve II - Week 10 Flashcards
What is megalopapilla, what is the lamina support like, and compared to normal, what is the risk of glaucoma like?
Congenitally large optic disc that has weak lamina support
Greater risk of glaucoma by 10x
What kind of notch is often seen in megalopapilla?
Horizontal notch in the neuroretinal rim
How should megalopapilla papients be treated as? Explain what this means (3).
Treat them as glaucoma patients
- visual fields
- IOP
- optic nerve head appearance photo
How should individuals with tight scleral sheaths be treated as?
Ischaemia suspects
Are blood vessel trifurcations an anomaly or normal?
Anomaly
List three general kinds of anomalous blood vessel patterns to look out for. Are they common or rare? Are they reliable in isolation? Explain.
Branching trifurcations Unusual insertions Unusual tortuosity Commonly normal, unreadable signs in isolation -flag for close evaluation
What is situs inversus and what two things is it often associated with?
It is a blood vessel distortion where there is a nasal detour of the temporal retinal vessels as they emerge from the disc
Associated with tilted discs and astigmatism
What are congenital arterial loops? How may it affect vision? What can rarely happen (2)?
Blood vessel that leaves and returns to the same place
May give transient vision loss
Rarely gives occlusions and vitreous haemorrhages
Can congenital venous shunts be acquired?
Yes in addition to congenital
What occurs with congenital venous shunts and give an example of a shunt.
Blood takes an alternative path, often choroidal flow
-optociliary shunt, from the retina to the choroid at the optic nerve head
How can acquired optociliary shunts occur? What can it be a possible re-establishment of?
Caused by chronic venous flow compromise (venous stasis) at the optic nerve head
Possibly formed by re-establishment of previously defunt/empty channels
List four common causes of acquired optociliary shunts.
ON drusen
Vein occlusion
Problems with blood vessels around the optic nerve head (papillophlebitis)
Problems with optic nerve head (chronic papillodema, glaucoma, papillitis, optic nerve sheath meningioma)
What happens to VA with optic nerve sheath meningioma?
Progressive vision loss from 6/6 to hand movement
Is RAPD present with optic nerve sheath meningioma?
Yes, if its unilateral
What happens to colour perception with optic nerve sheath meningioma?
Red saturation - dimmer in the impaired eye
List four stages of optic nerve appearance with optic nerve sheath meningioma.
Early optic nerve head swelling
Late optic atrophy
Venous congestion
Optociliary shunts
Does longstanding amblyopia ever get worse?
No, never
What should suspected loops and shunts be differentiated from?
anastamoses
How can congenital be differentiated from acquired optic loop/shunts?
Congenital - expect no VA loss or optic atrophy
What should you suspect if you see an acquired optociliary shunt, vision loss, and optic atrophy?
Optic nerve sheath meningioma
Who should you refer to if you suspect optic nerve sheath meningioma?
Neuroophthalmologist, ocular oncologist
Is the growth of optic nerve sheath meningioma rapid or slow? How does its position affect the difficulty of treatment? Can it diffuse intracranially or is it confined to the orbital space?
Slow growth, but the location is critical as it impacts vision
-is difficult due to proximity to the optic nerve
Can also diffuse intracranially
What three serial exams should be considered for a case of suspected optic nerve sheath meningioma?
Visual fields
Peripapillary RNFL with OCT
MRIs
What are congenital macrovessels? What path do they take (3)?
Abnormal single vein
- either enter or cross foveal avascular zone
- or cross horizontal raphe
What two things are congenital macrovessels rarely associated with?
Exudates and haemorrhages
What visual acuity do you expect with congenital macrovessels?
Normal
What is the cilioretinal artery derived from?
Short posterior ciliary artery
In what percentage of eyes would a cilioretinal artery be found? Describe where it is and what kind of appearance it has.
20%
It is found emerging from the middle of the optic disc and runs horizontally toward the macula (90%), and is thin
-has a hooked appearance
Is it a good thing to have a cilioretinal artery or does it present many problems? Explain.
Good to have
-it supplies the macula, good to have, especially in cases of CRAO
How can a cilioretinal artery be distinguished from any other vessel with a similar appearance emerging from the middle of the optic nerve head?
It has a distinct hooked appearance
What should you do and look out for if you see a cilioretinal artery?
Mostly conservative management
-photodocument for baseline and monitor for changes
What are pigmented peripapillary crescents? How are they different from scleral crescents? What makes deeper layer visible? What causes displaced pigment?
They are a pigmented crescent in the peripapillary region
Scleral crescents are not pigmented
Loss of overlying tissue makes deeper layers visible
Mobilisation of the RPE gives displaced pigment
List 5 possible causes of peripapillary crescents. Describe the look for each.
Congenital - smooth pigment Ageing - degeneration, moth eaten look Myopia - tilted disc, stretching, ectasia Glaucoma - loss of tissue Trauma - pigment clumping
What is optic nerve staphyloma?
Weakness in the scleral development at the optic nerve
What changes can be seen at the optic nerve head with optic nerve staphyloma?
Posterior outpouching, with near normal optic nerve at the bottom of the pouch
Compare the appearance of optic nerve staphyloma to thinning/ectasia.
It looks similar, but the outpouching is not the same as thinning/ectasia
Is there risk of retinal detachment with optic nerve staphyloma as with coloboma? Explain.
Yes, but maybe not to the same extent
What changes can be seen surrounding the optic nerve in optic nerve staphyloma (2)?
Pigmentary and degenerative changes
Is vision affected in optic nerve staphyloma?
Yes, from 6/9.5 to hand movement
What three visual impairments are common with optic nerve staphyloma?
Strabismus
Amblyopia
Myopic astigmatism
What is the prevalence of tilted discs?
3.5%
What can usually be seen with tilted disc syndrome at the ONH (aside from tilting)?
Usually some ON hypoplasia
In what percentage of tilted disc syndrome cases is it bilateral?
80%
What happens to the nerve fibre layer with tilted disc syndrome?
Downstream thinning of the nerve fibre layer
Does tilted disc syndrome typically have normal or anomalous blood vessel insertion patterns?
Anomalous
List three possible reasons for visual field defects due to tilted disc syndrome?
Retinal ectasia
Optic nerve hypoplasia
Possible pituitary involvement