[9] Intrinsic causes are due to thickening of the chiasm itself and extrinsic implies compression by another structure(gliomas, multiple sclerosis etc.[10]).

Other less common causes of chiasmal syndrome are metabolic, toxic, traumatic, inflammatory or infectious in nature (eg.

A lesion of this nucleus produces moderately to completely congruent visual field defects.

[20] Isolated lesions of the lateral geniculate nucleus are rare, it may be diagnosed by distinctive patterns of visual field loss.

[22] The optic radiation are axons from the neurons in the lateral geniculate nucleus to the primary visual cortex.

Bilateral lesions can cause complete cortical blindness and can sometimes be accompanied by a condition called Anton-Babinski syndrome.

A confrontational field test requires little or no special equipment and can be performed in any room, which is well illuminated.

Visual field assessment encompasses various perimetry techniques used in ophthalmology to evaluate how well someone can see in different areas of their vision.

These techniques include flicker perimetry, which assesses temporal visual function and spatial resolution targeting the M pathway; Frequency Doubling Technology (FDT), which utilizes an optical illusion to evaluate ganglion cell damage within the M pathway; Short-Wavelength Automated Perimetry (SWAP), isolating the S cone system to detect early glaucoma-related damage; High-pass Resolution Perimetry, focusing on resolution over the central visual field; Saccadic Vector Optokinetic Perimetry (SVOP), using eye tracking for assessing natural eye movements; and various standard and automated perimetry methods like Goldmann, Humphrey field analyzer, and Octopus, each employing different techniques for visual field assessment.

These diverse methods aid in diagnosing and monitoring ocular conditions, offering valuable insights into visual function and pathology.

[5][29][30] Modern computerized perimeters like humphrey field analyser (HFA) give more comprehensive and accurate reports than finger testing methods.

Careful clinical assessment could aid in accurate diagnosis of the cause of the visual field defect and loss of vision.