AIM:To compare the results of visual acuity(VA)measured by Early Treatment Diabetic Retinopathy Study(ETDRS)chart,5 m Standard Logarithm Visual Acuity(5 SL)chart,and 2.5 m Standard Logarithm Visual Acuity(2.5 SL)chart...AIM:To compare the results of visual acuity(VA)measured by Early Treatment Diabetic Retinopathy Study(ETDRS)chart,5 m Standard Logarithm Visual Acuity(5 SL)chart,and 2.5 m Standard Logarithm Visual Acuity(2.5 SL)chart in outpatients of age 12-80 y.METHODS:Each patient(totally 2000 outpatients)had both eyes tested with ETDRS chart at 4 m,5 SL chart at 5 m,and 2.5 SL chart at 2.5 m in random order.The VA values of outpatients were categorized by ages.VA values were expressed by log MAR recording method.RESULTS:The mean VA results of ETDRS charts,5 SL,and 2.5 SL chart were 0.52±0.28,0.50±0.30,and 0.46±0.28 log MAR,respectively.There was a statistically significant difference in the three eye charts in the whole group(P<0.001).For all subjects,the correlation of VA tested with three charts was statistically significant(Spearman correlation coefficient=0.944,0.937,0.946,all P<0.001).Bland–Altman analysis shows the 95%limits of agreement between the 5 SL and 2.5 SL chart were-0.182 to 0.210,-0.139 to 0.251,and-0.151 to 0.235 log MAR,respectively.CONCLUSION:The agreement between the three eye charts is not high.The VA measured by 5 SL chart is slightly better than that by ETDRS chart and 5 SL chart would be a suitable alternative when ETDRS chart are not available in the clinical situation.The VA measured by 2.5 SL chart is about 0.5 line better than VA tested with ETDRS chart,which may overestimate VA.展开更多
Perception is the ability to see,hear,or become aware of external stimuli through the senses.Visual stimuli are electromagnetic waves that interact with the eye and elicit a sensation.Sensations,indeed,imply the detec...Perception is the ability to see,hear,or become aware of external stimuli through the senses.Visual stimuli are electromagnetic waves that interact with the eye and elicit a sensation.Sensations,indeed,imply the detection,resolution,and recognition of objects and images,and their accuracy depends on the integrity of the visual system.In clinical practice,evaluating the integrity of the visual system relies greatly on the assessment of visual acuity,that is to say on the capacity to identify a signal.Visual acuity,indeed,is of utmost importance for diagnosing and monitoring ophthalmological diseases.Visual acuity is a function that detects the presence of a stimulation(a signal)and resolves its detail(s).This is the case of a symbol like“E”:the stimulus is detected,then it is resolved as three horizontal bars and a vertical bar.In fact,within the clinical setting visual acuity is usually measured with alphanumeric symbols and is a three-step process that involves not only detection and resolution,but,due to the semantic content of letters and numbers,their recognition.Along with subjective(psychophysical)procedures,objective methods that do not require the active participation of the observer have been proposed to estimate visual acuity in non-collaborating subjects,malingerers,or toddlers.This paper aims to explain the psychophysical rationale underlying the measurement of visual acuity and revise the most common procedures used for its assessment.展开更多
文摘AIM:To compare the results of visual acuity(VA)measured by Early Treatment Diabetic Retinopathy Study(ETDRS)chart,5 m Standard Logarithm Visual Acuity(5 SL)chart,and 2.5 m Standard Logarithm Visual Acuity(2.5 SL)chart in outpatients of age 12-80 y.METHODS:Each patient(totally 2000 outpatients)had both eyes tested with ETDRS chart at 4 m,5 SL chart at 5 m,and 2.5 SL chart at 2.5 m in random order.The VA values of outpatients were categorized by ages.VA values were expressed by log MAR recording method.RESULTS:The mean VA results of ETDRS charts,5 SL,and 2.5 SL chart were 0.52±0.28,0.50±0.30,and 0.46±0.28 log MAR,respectively.There was a statistically significant difference in the three eye charts in the whole group(P<0.001).For all subjects,the correlation of VA tested with three charts was statistically significant(Spearman correlation coefficient=0.944,0.937,0.946,all P<0.001).Bland–Altman analysis shows the 95%limits of agreement between the 5 SL and 2.5 SL chart were-0.182 to 0.210,-0.139 to 0.251,and-0.151 to 0.235 log MAR,respectively.CONCLUSION:The agreement between the three eye charts is not high.The VA measured by 5 SL chart is slightly better than that by ETDRS chart and 5 SL chart would be a suitable alternative when ETDRS chart are not available in the clinical situation.The VA measured by 2.5 SL chart is about 0.5 line better than VA tested with ETDRS chart,which may overestimate VA.
文摘Perception is the ability to see,hear,or become aware of external stimuli through the senses.Visual stimuli are electromagnetic waves that interact with the eye and elicit a sensation.Sensations,indeed,imply the detection,resolution,and recognition of objects and images,and their accuracy depends on the integrity of the visual system.In clinical practice,evaluating the integrity of the visual system relies greatly on the assessment of visual acuity,that is to say on the capacity to identify a signal.Visual acuity,indeed,is of utmost importance for diagnosing and monitoring ophthalmological diseases.Visual acuity is a function that detects the presence of a stimulation(a signal)and resolves its detail(s).This is the case of a symbol like“E”:the stimulus is detected,then it is resolved as three horizontal bars and a vertical bar.In fact,within the clinical setting visual acuity is usually measured with alphanumeric symbols and is a three-step process that involves not only detection and resolution,but,due to the semantic content of letters and numbers,their recognition.Along with subjective(psychophysical)procedures,objective methods that do not require the active participation of the observer have been proposed to estimate visual acuity in non-collaborating subjects,malingerers,or toddlers.This paper aims to explain the psychophysical rationale underlying the measurement of visual acuity and revise the most common procedures used for its assessment.
