Purpose:
To propose a novel system for grading vitreous haze in clinicalresearch in uveitis using digital photographs and standardizedscoring.
Methods:
The right fundus of a healthy 20-year-old was photographed witha Zeiss FF4 camera. Calibrated Bangerter diffusion filters inducingspatial contrast were placed on placed on the camera mount infront of the film plane. The "zero haze" eye was photographedwith the filters to simulate vitreous haze. Additional hazewas created by combining the 0.1 filter with other filters.A standardized scale was created with 9 steps from 0 to 3+ hazerelative to the Nussenblatt 5-step scale. The resulting scaleconsisted of photographs with acuities corresponding to 1.0,0.8, 0.4, 0.2, 0.1, 0.04, 0.02, 0.01, 0.002, with approximately0.3 log step between each gradation. A 98-slide test set ofclinical photographs of uveitis patients was created and reviewedin an HTML browser to allow real-time comparison with the standardphotos. 25 observers graded the test set under various testingconditions. Standard deviations were calculated for 9 groupsof test objects with average scores of 0 through 8.
Results:
The standard deviation of interobserver variability ranged froma low of 0.14 for a score of 8, to 1.13 for a score of 4. Theaverage standard deviation for all scores was 0.81.
Conclusions:
A nine-step photographic scale can reliably measure two-stepchanges in vitreous haze in photographs of uveitis patients.Validation with a clinical trial photo set and clinical gradesof haze would further support the utility of this method foruse in clinical research in uveitis.
Keywords: clinical research methodology • uveitis-clinical/animal model • vitreous