|10-2 and 24-2 visual field tests can be used in conjunction to strengthen detection of glaucomatous damage. Photo: Bisant Labib, OD. Click image to enlarge.|
A recent study suggested the severity of visual field (VF) loss in glaucoma can be predicted by abnormal test points within the central-most four points on the 24-2 test. However, it did not specify how perimetric parameters at the abnormal central-most four points would influence the paracentral eight points on 24-2 VF. In this study, the same researchers investigated the association between perimetric parameters at the abnormal central 12 points on 24-2 VF and the severity of central defects and related parafoveal scotomas on the 10-2.
A total of 64 eyes of 56 glaucoma patients with central VF defects on 24-2 VF testing and a mean deviation better than -7dB who completed both the 24-2 and 10-2 within six months were examined. Based on 10-2 pattern defects, eyes were categorized into three groups by the extent of field loss: severe (arcuate parafoveal scotoma), moderate (partial arcuate) and minimal. VF parameters at abnormal points within the central-most four and paracentral eight points on 24-2 VF were analyzed to predict the severity of central VF defects.
Eyes with arcuate scotoma showed more functional loss than eyes without on 10-2 VF. A significant association was observed between abnormal 24-2 VF threshold sensitivity lower than 20dB and defect values worse than -15dB with arcuate scotoma on 10-2 VF. This is consistent with previous studies. “There is also a close correspondence with the existing guideline for evaluating functional damage in glaucoma,” the study authors explained in their paper on the research, published in the Journal of Glaucoma.
A superior nasal defect in the central 5° on 24-2 VF was associated with an arcuate defect on 10-2 VF. Additionally, they argued, a comparison between the two types of defects—central-most four and paracentral eight points on 24-2 VF—provides invaluable information on the severity of central VF defects, which enables more accurate staging of the disease.
“In clinical practice, this study may improve early prediction of the severity of central VF defects by assessing threshold sensitivity and sensitivity loss at the abnormal central 12 points (<1%) within the central 10° on 24-2 VF in early glaucoma,” the authors concluded.
“Our results and recommendations are appropriate only for eyes without macula disease,” they added. “This data does not minimize the importance of a 10-2 VF test, especially in patients with a high risk of central VF defects. By using only 24-2 VF testing, one may miss glaucomatous damage of the macula that may occur prior to peripheral damage.”
The authors suggested additional research is needed to optimize clinical testing and healthcare resource utilization for early detection and proper evaluation of central VF defects on 24-2 VF for glaucoma management.
Chakravarti T, Moghimi S, Weinreb RN. Prediction of central visual field severity in glaucoma. J Glaucoma. April 7, 2022. [Epub ahead of print].