QuestionSBA
QuestionChoice
Retinal detachment occurs when there is separation of the neuro-sensory retina from the retinal pigment epithelium. This also presents with painless visual loss, but patients complain of flashing lights and floaters, and possibly a 'curtain' obscuring their vision (which would be the detached flap of retina.) Fundoscopy can reveal a detached homogenous floating grey membrane. This patient has none of these clinical features.
53166
e
Retinal detachment
QuestionChoice
Central retinal vein occlusion does result in sudden onset painless loss of vision. However, on fundoscopy, you would expect to find a stormy-sunset appearance with widespread haemorrhage, cotton wool spots, swollen optic discs, engorged veins, and chronically proliferative changes. This patient's fundoscopic examination is normal. Risk factors include pro-thrombotic stages as well as cardiac risk factors, which this patient does not have.
53163
b
Central retinal vein occlusion
QuestionChoice
Branch retinal vein occlusion does result in sudden onset painless loss of vision. However, on fundoscopy, you would expect to find haemorrhage, cotton wool spots, swollen optic discs, and engorged veins within the area of occlusion. This patient's fundoscopic examination is normal. Risk factors include pro-thrombotic stages as well as cardiac risk factors, which this patient does not have.
53164
c
Branch retinal vein occlusion
QuestionChoice
This is incorrect because damage to the superior optic radiation within the parietal lobne  would cause an inferior homonymous quadrantanopia.
53165
d
Lesion of the superior optic radiation
QuestionChoice
This patient has a right superior homonymous quadrantanopia visual field defect caused by damage to the left inferior optic radiation. This is likely due to her recent temporal lobe surgery.  the left temporal lobe. Damage to the temporal optic radiation fibres (Meyer's loop) causes superior contralateral quadrantanopias. Damage to the parietal optic radiation fibres result in inferior contralateral quadrantanopias.
53162
a
Lesion of the inferior optic radiation
QuestionComment
Inferior radiation does superior vision 
23899
QuestionComment
and the numbers 12-3 are where on a clock
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# Summary

Visual field loss encompasses a range of distinct patterns, each indicative of underlying pathologies affecting different segments of the visual pathway. Monocular vision loss often results from retinal, optic nerve, or corneal disorders in one eye. Bitemporal hemianopia, characteristic of pituitary tumours and craniopharyngiomas, involves the loss of outer visual fields in both eyes. Contralateral homonymous hemianopia points to stroke or occipital lobe lesions, with loss of half the visual field in both eyes on the same side. Quadrantanopias may stem from stroke or trauma, leading to the loss of a quarter of the visual field. In occipital lobe lesions, macular sparing preserves central vision despite peripheral field loss. Recognizing these patterns and their differentials is crucial for accurate diagnosis and tailored management.


# Pathologies seen at different parts of the optic pathway

Different parts of the optic pathway present as various forms of visual deficits when disrupted.


| **Visual Field Loss Pattern**            | **Optic Pathway**       | **Differential Diagnoses**                          |
|----------------------------------------|-------------------------|----------------------------------------------------|
| Monocular Vision Loss                   | Optic Nerve               | - Retinal disorders, optic nerve disorders, corneal disorders                 |
| Bitemporal Hemianopia                   | Optic Chiasm          | - Pituitary tumours                      |
| Contralateral Homonymous Hemianopia     | Optic Radiation       | - Stroke affecting optic radiation, occipital lobe lesions                     |
| Quadrantanopias                        | Optic Radiation       | - Stroke affecting specific pathways in the optic radiation, trauma, craniopharyngioma                    |
| Macular Sparing in Occipital Lobe Lesions |  Occipital Lobe      | - Occipital infarcts or haemorrhages                  |


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# Further Details 

Considering that the fibres of each optic radiation that correspond to the lower retina (which receives stimulation by the upper half of the visual field) pass through the temporal lobe while the fibres that carry visual stimuli from the upper retina (representing the lower half of the visual fields) pass through the parietal lobe, it is clear that:

- A lesion in the temporal lobe would cause contralateral homonymous superior (upper) quadrantanopia

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- A lesion in the parietal lobe would cause contralateral homonymous inferior (lower) quadrantanopia
	- A mneumonic for remembering this is **PITS** - P - parietal I - inferior; T - temporal S - superior
- Parietal lobe damage also manifests as a defect of attention in the contralateral visual field, astereognosis, constructional apraxia (non-dominant), dressing apraxia (non-dominant) and ideomotor apraxia (dominant). Right hemisphere (i.e. non-dominant) parietal lesions are particularly prone to producing visual neglect. 
- A lesion in the occipital lobe would cause contralateral homonymous hemianopia
	- When an occipital lobe lesion occurs, it may damage a specific area of the visual cortex, resulting in visual field loss. However, the central representation of the macula has a larger cortical area dedicated to it, making it less vulnerable to damage. As a result, the central vision remains intact, creating a spared or preserved area of vision even in the presence of peripheral visual field loss.

# References

1. [Neuro-Ophthalmology Review Manual](https://www.thieme.com/books-main/ophthalmology/product/1040-neuro-ophthalmology-review-manual)
2. [NICE Guidelines: Stroke and Transient Ischaemic Attack](https://www.nice.org.uk/guidance/cg68)
3. [Visual Field Defects Overview on MedlinePlus](https://medlineplus.gov/ency/article/003879.htm)
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How the visual fields are affected in a quadrantanopia.
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How the visual fields are affected in a bitemporal hemianopia
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How the visual fields are affected in a homonymous hemianopia.
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Visual field loss
Topic
16
Ophthalmology
10693
Damage to the left inferior optic radiation can cause right superior homonymous quadrantanopia, often following temporal lobe surgery.
A 54-year-old woman presents to A&E with sudden, painless loss of vision. This has not happened to her before. There was no obvious trigger, since she was sitting at home when this happened. She has a past medical history of severe left temporal lobe epilepsy and recently underwent surgery for this. When asked to point out the numbers on a clock face, she is only able to see from number 4 to 11 in both eyes. Fundoscopic examination is unremarkable.

What is responsible for this patient's visual field defect?
a