Laboratory Study
Eye (2006) 20, 98–106. doi:10.1038/sj.eye.6701781; published online 14 January 2005
Pointwise linear progression criteria and the detection of visual field change in a glaucoma trial
M R Wilkins1,3, F W Fitzke2 and P T Khaw1,3
- 1Wound Healing Research Unit, Institute of Ophthalmology, London, UK
- 2Department of Visual Science, Institute of Ophthalmology, London, UK
- 3Moorfields Eye Hospital, City Road, London, UK
Correspondence: MR Wilkins, Moorfields Eye Hospital, 162 City Road, London, EC1V 2PD. Tel: +44 207 2533411; E-mail: mail@markwilkins.co.uk
Received 13 April 2004; Revised 20 October 2004; Accepted 20 October 2004; Published online 14 January 2005.
Abstract
Background
Current pointwise linear regression (PLR) change criteria for visual field analysis are largely empirical.
Methods
Two independent sets of Humphrey Field Analyzer fields were analysed using PLR. Set i, 56 patients, and set ii, 97 patients, were followed over 16 months. Criteria were tested against set i, and then validated using set ii. Each criterion specified a fixed critical slope of 1 dB/year and with a range of significance from P<0.001 to 0.05. The criteria were varied by altering location number, cluster arrangement, and by requiring points to show change over both 12 and 16 months. True glaucomatous change was differentiated from noise by looking for exclusive progression (EP), the detection of progression without detection of improvement.
Results
Set i required 1 point to have a slope of 1 dB/year and P<0.05 labelled 64% progressing and 58% improving, whereas several stricter criteria were capable of detecting EP. Two points in a perimetric nerve fibre bundle (PNFB) cluster gave optimal EP detection, labelling 8.9% progressing in set i and 7.2% progressing in set ii with a cutoff P-value of 0.026 inset i and 0.013 inset ii.
Conclusion
Lax PLR criteria detect large amounts of change. Validating criteria using two data sets allow selection of better criteria, capable of detecting EP. The criterion involving 2 points changing in a PNFB cluster offers the best option for exclusively detecting progression.
Keywords:
visual field, linear regression, glaucoma
MORE ARTICLES LIKE THIS
These links to content published by NPG are automatically generated
NEWS AND VIEWS
Seeking a function for spontaneous neurotransmission
Nature Neuroscience News and Views (01 Aug 2006)
