this retrospective study included 964 eyes from 500 subjects including 128 healthy normal eyes and 836 eyes with primary open angle glaucoma had various stages of visual field defects ( 572 early , 164 moderate and 100 severe ) . both eyes of each patient were included in the study if they satisfied the entry criteria as follows : each eye had a best corrected visual acuity of 20/25 or better , a spherical equivalent refractive error between -5 and + 5 diopters , clear ocular media with no clinically significant cataract , a normal open angle , and no previous intraocular surgical history . the diagnosis of glaucoma was based on the presence of typical glaucomatous optic disc damage , as judged by stereoscopic examination by a glaucoma specialist ( y. j. hong ) , and the presence of glaucomatous visual field loss as measured by sap . the patients had no significant ocular diseases other than glaucoma and no other diseases affecting visual fields . the normal controls had no visual field changes on sap , intraocular pressure below 21 mmhg , no optic nerve head or retinal nerve fiber layer changes suggestive of glaucoma , no other ocular disease or surgical history , no diabetes , and no family history of glaucoma . all subjects were examined using sap ( carl zeiss meditec inc , dublin , ca ) with a 30 - 2 swedish interactive threshold algorithm ( sita ) standard strategy . the minimal visual field abnormality was determined by sap and was defined as significant when : ( 1 ) the glaucoma heimifield test was " outside normal limits " in 2 consecutive fields ; ( 2 ) 3 or more adjacent points were present in an expected location of the central 24-degree field that depressed below the 5% level on the pattern deviation plot ( pdp ) , one of which must have been below the 1% level in 2 consecutive fields ; or ( 3 ) pattern standard deviation ( psd ) was significant below the 5% level in 2 consecutive tests.10 visual field defects were divided into 3 stages : early , moderate , and severe.11 the early stage of a glaucomatous visual field defect was defined as having : ( 1 ) a mean deviation ( md ) of no worse than -6db , ( 2 ) fewer than 25% of the points depressed below the 5% level and fewer than 15% of points depressed below the 1% level on pdp , and ( 3 ) no point within the central 5-degree field with a sensitivity of less than 15db . a moderate stage of visual field defect was defined as having : ( 1 ) md of worse than -6 db but no worse than -12db , ( 2 ) fewer than 50% of the points depressed below the 5% level and fewer than 25% of points depressed below the 1% level on pdp , ( 3 ) no point within the central 5-degree field with a sensitivity of less than or equal to 0 db , and ( 4 ) only 1 hemifield containing a point with sensitivity less than 15db within 5 degrees of fixation . criteria for severe defects in glaucoma were defined as : ( 1 ) md worse than -12 db , ( 2 ) more than 50% of the points depressed below the 5% level and more than 25% of points depressed below the 1% level on pdp , ( 3 ) any point within the central 5-degree field with a sensitivity of less than or equal to 0 db , and ( 4 ) both hemifields containing a point(s ) with sensitivity less than 15 db within 5 degrees of fixation . the rnfl photographs were recorded with blue reflectance ( " red - free " ) images using the hra1 . two of authors ( s. hong & s. j. ha ) interpreted the rnfl photos using the two scoring systems ( table 1 ) under the masking of the diagnosis . for darkness scores , the contrast and brightness of rnfl photos were adjusted to distinguish sharply the retinal blood vessels from the background using heidelberg eye explorer program ( heidelberg engineering , dossenheim , germany ) . on location scores a reference plane was set across the horizontal raphe dividing the papillomacular bundle into two vertical halves . rnfl in the 15 degrees above and below this reference plane was termed the ' temporal ' sector . rnfl in the 75 degrees from the end of the ' temporal ' sector to the vertical line dividing the optic nerve head into two halves was termed as ' supero- , and infero- temporal ' sectors for the respective vertical positions . the remaining 180 degrees of nasal rnfl was designated as the ' nasal ' sector . in cases with a large or multiple rnfl defect over several sectors , if the two scores did not agree with each other , the other two glaucoma specialists ( y. j. hong & g. j. seong ) were asked to interpret it . table 1 showed the scoring methods to assess the rnfl photo.9 the rnfl defect score i was a summation of each score , and the rnfl defect score ii was the product of each score - rnfl defect , darkness , width , and location . the rnfl defect score i could range from 0 to 11 , and the rnfl defect score ii could range from 0 to 54 . the interval between the sap and rnfl photography was less than 1 month . to assess correlations between rnfl photographs using hra1 and sap , we compared two rnfl defect scores ( rnfl defect score i and ii ) and visual field indices ( md and psd ) of sap . statistical comparisons between groups were conducted using an independent 2-tailed student t - test , and p - values less than 0.05 were considered statistically significant . statistical analysis for linear regression was performed using the medcalc for windows program , version 7.6.0.0 ( medcalc software , mariakerke , belgium ) . statistical analyses other than linear regression were carried out using the program spss for windows , version 11.5 ( spss inc , chicago , il ) . this retrospective study included 964 eyes from 500 subjects including 128 healthy normal eyes and 836 eyes with primary open angle glaucoma had various stages of visual field defects ( 572 early , 164 moderate and 100 severe ) . both eyes of each patient were included in the study if they satisfied the entry criteria as follows : each eye had a best corrected visual acuity of 20/25 or better , a spherical equivalent refractive error between -5 and + 5 diopters , clear ocular media with no clinically significant cataract , a normal open angle , and no previous intraocular surgical history . the diagnosis of glaucoma was based on the presence of typical glaucomatous optic disc damage , as judged by stereoscopic examination by a glaucoma specialist ( y. j. hong ) , and the presence of glaucomatous visual field loss as measured by sap . the patients had no significant ocular diseases other than glaucoma and no other diseases affecting visual fields . the normal controls had no visual field changes on sap , intraocular pressure below 21 mmhg , no optic nerve head or retinal nerve fiber layer changes suggestive of glaucoma , no other ocular disease or surgical history , no diabetes , and no family history of glaucoma . all subjects were examined using sap ( carl zeiss meditec inc , dublin , ca ) with a 30 - 2 swedish interactive threshold algorithm ( sita ) standard strategy . the minimal visual field abnormality was determined by sap and was defined as significant when : ( 1 ) the glaucoma heimifield test was " outside normal limits " in 2 consecutive fields ; ( 2 ) 3 or more adjacent points were present in an expected location of the central 24-degree field that depressed below the 5% level on the pattern deviation plot ( pdp ) , one of which must have been below the 1% level in 2 consecutive fields ; or ( 3 ) pattern standard deviation ( psd ) was significant below the 5% level in 2 consecutive tests.10 visual field defects were divided into 3 stages : early , moderate , and severe.11 the early stage of a glaucomatous visual field defect was defined as having : ( 1 ) a mean deviation ( md ) of no worse than -6db , ( 2 ) fewer than 25% of the points depressed below the 5% level and fewer than 15% of points depressed below the 1% level on pdp , and ( 3 ) no point within the central 5-degree field with a sensitivity of less than 15db . a moderate stage of visual field defect was defined as having : ( 1 ) md of worse than -6 db but no worse than -12db , ( 2 ) fewer than 50% of the points depressed below the 5% level and fewer than 25% of points depressed below the 1% level on pdp , ( 3 ) no point within the central 5-degree field with a sensitivity of less than or equal to 0 db , and ( 4 ) only 1 hemifield containing a point with sensitivity less than 15db within 5 degrees of fixation . criteria for severe defects in glaucoma were defined as : ( 1 ) md worse than -12 db , ( 2 ) more than 50% of the points depressed below the 5% level and more than 25% of points depressed below the 1% level on pdp , ( 3 ) any point within the central 5-degree field with a sensitivity of less than or equal to 0 db , and ( 4 ) both hemifields containing a point(s ) with sensitivity less than 15 db within 5 degrees of fixation . the rnfl photographs were recorded with blue reflectance ( " red - free " ) images using the hra1 . two of authors ( s. hong & s. j. ha ) interpreted the rnfl photos using the two scoring systems ( table 1 ) under the masking of the diagnosis . for darkness scores , the contrast and brightness of rnfl photos were adjusted to distinguish sharply the retinal blood vessels from the background using heidelberg eye explorer program ( heidelberg engineering , dossenheim , germany ) . on location scores a reference plane was set across the horizontal raphe dividing the papillomacular bundle into two vertical halves . rnfl in the 15 degrees above and below this reference plane was termed the ' temporal ' sector . rnfl in the 75 degrees from the end of the ' temporal ' sector to the vertical line dividing the optic nerve head into two halves was termed as ' supero- , and infero- temporal ' sectors for the respective vertical positions . the remaining 180 degrees of nasal rnfl was designated as the ' nasal ' sector . in cases with a large or multiple rnfl defect over several sectors , if the two scores did not agree with each other , the other two glaucoma specialists ( y. j. hong & g. j. seong ) were asked to interpret it . table 1 showed the scoring methods to assess the rnfl photo.9 the rnfl defect score i was a summation of each score , and the rnfl defect score ii was the product of each score - rnfl defect , darkness , width , and location . the rnfl defect score i could range from 0 to 11 , and the rnfl defect score ii could range from 0 to 54 . to assess correlations between rnfl photographs using hra1 and sap , we compared two rnfl defect scores ( rnfl defect score i and ii ) and visual field indices ( md and psd ) of sap . statistical comparisons between groups were conducted using an independent 2-tailed student t - test , and p - values less than 0.05 were considered statistically significant . statistical analysis for linear regression was performed using the medcalc for windows program , version 7.6.0.0 ( medcalc software , mariakerke , belgium ) . statistical analyses other than linear regression were carried out using the program spss for windows , version 11.5 ( spss inc , chicago , il ) . nine hundred sixty - four eyes from 500 subjects including 128 healthy normal eyes and 836 eyes with primary open angle glaucoma were evaluated . in the glaucoma group , 572 eyes showed early visual field defects on sap , 164 showed moderate defects , and 100 showed severe defects . demographic data and visual field indices for sap of subjects are shown in table 2 , and the scoring systems for rnfl photographs using hra1 are shown in table 3 . , 3 show the correlation between rnfl defect scores and visual field indices of sap . correlations between the rnfl defect score ii and md of sap were the strongest ( y = 9.515 - 1.772 x , r = -0.675 , p<0.001 ) ( fig . correlations between the rnfl defect score i and psd of sap were the worst ( y=5.841 + 0.380 x , r=0.481 , p<0.001 ) ( fig . since the rnfl defect score ii and md of sap showed the strongest correlation , correlations between these variables for various stages of visual field defect on sap were evaluated , as shown in table 5 . the r value of early , moderate , severe , and control groups was -0.404 , -0.129 , 0.034 and -0.313 , respectively . the strongest correlation between rnfl defect score ii and md of sap was in the early stage visual field loss group ( y=3.980 - 4.125 x , p<0.001 ) . the second strongest correlation was in the control group ( y=2.849 - 2.386 x , p<0.001 ) . additionally , linear regression analysis for rnfl defect score ii and md of sap in early glaucoma and control groups showed good correlation ( y=4.604 - 6.620 x , r=-0.524 , p<0.001 ) ( fig . though rnfl photography is an important part of the examination of glaucoma patients , it is a subjective and qualitative method . some researchers have tried to develop a grading system for rnfl photography,6 - 8 but interpretation of rnfl photos has remained very difficult . in the present study , we recorded rnfl photographs with blue reflectance ( " red - free " ) images using hra1 . rnfl loss was assessed using a new scoring system ( table 1).9 on location scores , score " 1 " represents inferotemporal or superotemporal area , " 2 " represents nasal area , and " 3 " represents temporal area ( fig . since the inferotemporal and superotemporal sectors are the early affected sectors and nasal sector is the late affected sector in glaucoma,12 - 15 we gave additional points to the nasal area . the rnfl defect score i was a summation of each score , and the rnfl defect score ii was the product of each score - rnfl defect , darkness , width , and location . the rnfl defect score i could range from 0 to 11 , and the rnfl defect score ii could range from 0 to 54 . 5 . the two new rnfl defect scoring systems strongly correlated with visual field indices of sap . among various combinations , the rnfl defect score ii and the md of sap showed the strongest correlation ( r = -0.675 , p<0.001 ) ( fig . additionally , these measurements correlated more strongly in the group with normal and early visual field loss compared to the moderate and severe visual field loss groups ( r=-0.313 , p<0.001 ) ( fig . this suggests that rnfl photography may be more meaningful in early stage glaucoma patients , and rnfl defect score ii can be used to interpret rnfl photography using hra1 for early glaucoma patients . in this study , we included the glaucoma patients who had a typical glaucomatous optic disc damage and a glaucomatous visual field defect . additionally , the normal control participants had no optic nerve head or retinal nerve fiber layer changes and no visual field defect . these inclusion criteria may be biased particularly in the early glaucoma patients . in conclusion , we have presented a method for the semi - quantitative interpretation of rnfl photos through the use of a new scoring system for rnfl photography . this method provides good reliability and may extend the evaluation rnfl photography to non - specialists .