Visual field defects.pptx

All type of visual field defects are discussed here.

1. Visual field defects PRESENTED BY: MD JARGIS ALAM (20ISMO16) From: 2nd year Optometry SMD, UOH

2. The normal extent of field of vision • The Normal visual field is defined as "Island of vision surrounded by a sea of blindness" 60°nasally. 50°superiorly 70°inferiorly. 90° temporally

3. Terms Visual field defect - a portion of visual field missing. This may be: central (e.g. optic disc or nerve problem) peripheral (along the visual pathways from the optic chiasm back).

4. C ommon causes of VF defect Central field loss occurs with: 1.Optic neuropathy 2.Macular degeneration 3.Macular hole 4.Cone dystrophies A number of rare conditions like Best's disease, Stargardt's disease and achromatopsia.

5. Common causes of VF defect Peripheral field loss occurs with: 1.Retinitis pigmentosa 2.Chorioretinitis 3.Glaucoma 4. Retinal detachment 5.Leber's optic atrophy

6. Visual field defects Scotoma - this is a type of visual field defect. It is a defect surrounded by normal visual field. Relative scotoma - an area where objects of low luminance cannot be seen but larger or brighter ones can. Absolute scotoma - nothing can be seen at all within that area.

7. Hemianopia binocular visual defect in each eye's hemifield. Bitemporal hemianopia - the two halves lost are on the outside of each eye's peripheral vision, effectively creating a central visual tunnel. Homonymous hemianopia - the two halves lost are on the corresponding area of visual field in both eyes, i.e. either the left or the right half of the visual field.

8. Cont. Altitudinal hemianopia - refers to the dividing line between loss and sight being horizontal rather than vertical, with visual loss either above or below the line. Quadrantanopia - is an incomplete hemianopia referring to a quarter of the schematic 'pie' of visual field loss. Sectoral defect - is also an incomplete hemianopia

9. Homonymous hemianopia Bitemporal hemianopia

10. Altitudinal hemianopia Quadrantanopia Sectoral defect

11. Visual Field Examinations Six types of visual field tests 1.Confrontation visual field test. 2. Automated static perimetry test. 3.Kinetic visual field test. 4.Frequency doubling perimetry. 5.Electroretinography. 6.Amsler grid

12. AMSLER GRID CHART Important in testing macular function when v/a decreased or distorted Chart consisting of white lines on black background & central white dot for fixation 10 cm square divided in 5mm square It is use to evaluate 20 degree of v/f surrounding fixation. This test is use for screening & diagnostic purpose

13. Procedure Test is done uniocularly Patients pupil should not be dilated Patient should were their full refractive correction Use good illumination on chart Hold the chart at 30cm from patients eye. Ask the patient to fixate on central white dot & tell patient while looking on central dot give the answers of following questions-

14. Questionaries 1.Can you see the central white dot in the center of grid? 2.While looking at central dot ,can you see all four quadrants of chart simultaneously? 3.Does the grid appears to have any missing or distorted area? 4.Are there any area of grid that have an unusual appearance? 5.Are any square blurring/missing?

15. Replies •If the answer is ‘Yes’, a central scotoma is unlikely unless the clinician is obtaining a false-positive response due to poor patient compliance. •If the answer is ‘ It looks washed out’ or ‘It seems slightly blurry’, one should suspect for a relative central scotoma.