Pointwise topographical and longitudinal modeling of the visual field in glaucoma.
OBJECTIVE
To develop a suitable mathematical model for the description of the pointwise distribution of sensitivity across the visual field in glaucoma.


METHODS
The pointwise distribution of sensitivity at any given stimulus location for any given examination was described by a joint topographical and longitudinal model. The topographical element modeled the pointwise distribution of sensitivity using a second-order polynomial function in terms of the respective stimulus coordinates whereas the longitudinal element modeled the pointwise distribution of sensitivity using multiple linear regression in terms of the sensitivity at the given location determined at one or more previous examinations. The sample comprised Humphrey Field Analyser (Humphrey Instruments, San Leandro, CA) Program 30-2 and 24-2 fields from 49 patients attending a glaucoma clinic for an average of 3 years.


RESULTS
The constant term of the polynomial correlated highly with the mean deviation and moderately with the pattern standard deviation. The goodness-of-fit between the modeled and the measured field increased as an exponential function of the number of previous examinations. The median R2 was 19.6% for the first examination and 83.6% for the sixth examination. The group median optimum percentage of error between the measured and modeled sensitivity at each test location was below 10% (i.e., less than 3 dB), increased with increase in eccentricity, was greater at the extremities of the superior field and varied as a function of the severity of the field loss.


CONCLUSIONS
The model seems to be a promising way to evaluate visual field progression.
Wild
J M
JM
Department of Vision Sciences, Aston University, Birmingham, United Kingdom.
Hussey
M K
MK
Flanagan
J G
JG
Trope
G E
GE
D005901:Glaucoma / Q000503:physiopathology*; D006801:Humans; D008433:Mathematics; D008875:Middle Aged; D008954:Models, Biological; D012044:Regression Analysis; D058609:Visual Field Tests / Q000379:methods; D014794:Visual Fields / Q000502:physiology*