Eye Disease Data: Diabetic Retinopathy

From Agresti's 2010 ordinal book, an eye disease data set involving ordinal measurements of retinopathy in left and right eyes of insulin-taking young diabetics.

Usage

data("eyed")

Format

A data frame with 720 observations on the following 23 variables.

rrl: a numeric vector
lrl: a numeric vector
rl: a numeric vector
rme: Right eye macular oedema (absent = 0, present = 1)
lme: Left eye macular oedema (absent = 0, present = 1)
rre: Right eye refraction index
lre: Left eye refraction index
riop: Right eye intraocular pressure
liop: Left eye intraocular pressure
age: Age at diagnosis (values are less than 30 years)
diab: Duration of diabetes (years)
gh: Glycosylated haemoglobin level
sbp: Systolic blood pressure (mmHg)
dbp: Diastolic blood pressure (mmHg)
bmi: Body mass index, in kg / m2, rounded to an integer
pr: a numeric vector
sex: male = 0, female = 1
prot: Proteinuria (absent = 0, present = 1)
dose: a numeric vector
resid: a numeric vector
rerl: Right eye severity of retinopathy, an ordered factor with levels None, Mild, Moderate, Proliferative
lerl: Same as rerl but for left eye
rl2: a numeric vector

Details

The data is used as the example in Section 9.1.3 of Agresti (2010), entitled Eye Disease Risk Factors. Williamson and Kim (1996) describe a Wisconsin epidemiological study in which insulin-taking young diabetics were examined for diabetic retinopathy (both prevalence and severity) in both eyes. One could fit a proportional odds model to each eye. The retinopathy severity is ordinal: None, Mild, Moderate, Proliferative. Variables lerl and rerl can be considered the primary responses.

Source

https://users.stat.ufl.edu/~aa/ordinal/data.html retrieved in Nov 2025.

References

Agresti, A. (2010). Analysis of Ordered Categorical Data, Second Edition. Wiley: Hoboken, NJ, USA.

Williamson, J. and Kim, K. (1996). A global odds ratio regression model for bivariate ordered categorical data from opthalmologic studies. Statistics in Medicine 15, 1507–1518.

Examples

summary(eyed)
#>       rrl             lrl             rl             rme         
#>  Min.   :1.000   Min.   :1.00   Min.   : 3.00   Min.   :0.00000  
#>  1st Qu.:1.000   1st Qu.:1.00   1st Qu.:27.00   1st Qu.:0.00000  
#>  Median :2.000   Median :2.00   Median :35.00   Median :0.00000  
#>  Mean   :2.399   Mean   :2.41   Mean   :32.63   Mean   :0.04583  
#>  3rd Qu.:3.000   3rd Qu.:3.00   3rd Qu.:40.00   3rd Qu.:0.00000  
#>  Max.   :8.000   Max.   :7.00   Max.   :40.00   Max.   :1.00000  
#>       lme               rre               lre               riop      
#>  Min.   :0.00000   Min.   :-15.125   Min.   :-15.000   Min.   : 5.00  
#>  1st Qu.:0.00000   1st Qu.: -2.000   1st Qu.: -2.000   1st Qu.:14.00  
#>  Median :0.00000   Median : -0.500   Median : -0.500   Median :16.00  
#>  Mean   :0.04167   Mean   : -1.108   Mean   : -1.141   Mean   :16.07  
#>  3rd Qu.:0.00000   3rd Qu.:  0.000   3rd Qu.:  0.000   3rd Qu.:18.00  
#>  Max.   :1.00000   Max.   : 14.375   Max.   : 14.500   Max.   :31.00  
#>       liop            age             diab              gh      
#>  Min.   : 8.00   Min.   : 0.40   Min.   : 1.200   Min.   : 6.0  
#>  1st Qu.:14.00   1st Qu.: 9.00   1st Qu.: 5.875   1st Qu.:10.8  
#>  Median :16.00   Median :13.40   Median :10.200   Median :12.3  
#>  Mean   :16.02   Mean   :14.76   Mean   :12.837   Mean   :12.6  
#>  3rd Qu.:18.00   3rd Qu.:20.40   3rd Qu.:17.300   3rd Qu.:14.2  
#>  Max.   :31.00   Max.   :29.90   Max.   :55.200   Max.   :23.3  
#>       sbp             dbp              bmi              pr       
#>  Min.   : 78.0   Min.   : 43.00   Min.   :14.00   Min.   :25.00  
#>  1st Qu.:110.0   1st Qu.: 71.00   1st Qu.:21.00   1st Qu.:37.00  
#>  Median :119.0   Median : 77.00   Median :23.00   Median :41.00  
#>  Mean   :121.8   Mean   : 77.54   Mean   :23.45   Mean   :41.58  
#>  3rd Qu.:130.0   3rd Qu.: 84.00   3rd Qu.:25.00   3rd Qu.:46.00  
#>  Max.   :218.0   Max.   :117.00   Max.   :51.00   Max.   :66.00  
#>       sex              prot             dose           resid      
#>  Min.   :0.0000   Min.   :0.0000   Min.   :0.000   Min.   :1.000  
#>  1st Qu.:0.0000   1st Qu.:0.0000   1st Qu.:1.000   1st Qu.:1.000  
#>  Median :0.0000   Median :0.0000   Median :1.000   Median :1.000  
#>  Mean   :0.4958   Mean   :0.1389   Mean   :1.422   Mean   :1.465  
#>  3rd Qu.:1.0000   3rd Qu.:0.0000   3rd Qu.:2.000   3rd Qu.:2.000  
#>  Max.   :1.0000   Max.   :1.0000   Max.   :2.000   Max.   :2.000  
#>             rerl                lerl          rl2        
#>  None         :275   None         :268   Min.   : 1.000  
#>  Mild         :270   Mild         :277   1st Qu.: 1.000  
#>  Moderate     :128   Moderate     :127   Median : 3.000  
#>  Proliferative: 47   Proliferative: 48   Mean   : 3.329  
#>                                          3rd Qu.: 5.000  
#>                                          Max.   :10.000