13987690
| Question | Answer |
| Define and describe the visual field | Definition: the area of one's surroundings that is visual at one time with a steadily fixating eye Description: Each eye is able to see ~60 degrees nasally, ~100 degrees temporally, ~60 degrees superiorly and 75 degrees inferiorly * Anything outside the central 30 degrees is considered the periphery. * Can be represented as " island/hill of vision" where visual sensitivity increases from zero peripherally to maximum centrally - shaped dependent on state of adaptation, colour, spatial properties (size) and temporal properties. |
| Amsler grid test | Use: for checking central scotoma/distortions (metamorphopsia) Pros: quick, cheap and portable (easy for self-monitoring) When to use: cases of central visual disturbance (unexplained decrease in VA, macular pathologies), monitoring AMD Results: metamorphopsia - subtle macular disorders (e.g. swelling), scotoma - severe retinal or optic nerve disease |
| Confrontation visual field test | Must be preformed on all patients Use: screening for large, absolute scotoma - 9/10 postchiasmal defects detected - 1/3 prechiasmal defects detected Extinction: present to 2 quadrants - patient gets it wrong but present to either quadrant - patient gets it right Neglect: Present to 2 quadrants - Px keeps neglecting 1 quadrant |
| Explain how static and kinetic perimetry are performed and to relate them to the hill of vision | Perimetry - used to measure visual function outside fovea (for glaucoma detection and management) Static perimetry * Clinical procedure: in fixed position with varying intensity * Results: plotted as heights on hill of vision at specific position Kinetic perimetry * Clinical procedure: Variable position at constant intensity * Results: plotted as isopter (changing width of hill |
| Describe some fundamental properties of standard automated perimetry (SAP) | Standard Automated Perimetry * computerise static perimetry (2 types: Medmont and Humphrey) * measures sensitivity to small white lights presented on dimly illuminated background (increment threshold) * performance is compared to an age-matched normative database * sensitivity is measured in decibel * can be performed using different stimulus patterns * reasonably sensitivity for detecting defects but not diagnosing or detecting early subtle changes * 2 - 8 mins |
| Confrontation - Red Cap Testing | Use: testing function of optic nerve |
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