A new specialized visual acuity chart for amblyopic children aged 3-5 years old:development and its clinical applications

AIM:To Introduce a new specialized visual acuity chart for amblyopic children aged 3-5 years old and its clinical applications.METHODS:The new visual acuity chart and notations were designed based on Weber-Fechner law.The optotypes were red against a white background and were specially shaped four basic geometric symbols:circle,square,triangle,and cross.A regular geometric progression of the optotype sizes and distribution was employed to arrange in 14 lines.The progression rate of the optotype size between two lines was 1.2589 and the testing distance was 3m.Visual acuity score could be recorded as logMAR notation or decimal notation.Agestratified diagnostic criteria for amblyopia established by consensus statement on diagnosis of amblyopia(2011)among members of the Strabismus and Pediatric Ophthalmology Group,Ophthalmology Society,Chinese Medical Association(SPOGOSCMA)were illustrated in the new visual acuity chart.RESULTS:When assessing visual acuity in children aged 3-5 years old,this new visual acuity chart that consists of four symmetrical shapes(triangle,square,cross,and circle)overcame an inability to recognize the letters of the alphabet and difficulties in designating the direction of black abstract symbols such as the tumbling’E’or Landolt’C’,which the subjects were prone to lose interest in.The visual acuity score may be recorded indifferent notations:decimal acuity and logMAR.These two notations can be easily converted each other in the new eye chart.The measurements of this new chart not only showed a significant correlation and a good consistency with the international standard logarithmic visual acuity chart(r=0.932,P【0.01),but also indicated a high test-retest reliability(89%of retest scores were within 0.1 logMAR units of the initial test score).CONCLUSION:The results of this study support the validity and reliability of distance visual acuity measurements using the new eye chart in children aged3 to 5 years over a wide range of visual acuities,and the new eye chart is great for early detection of amblyopia.It can be applied in various clinical settings.

A comparison of visual acuity measured by ETDRS chart and Standard Logarithmic Visual Acuity chart among outpatients

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.