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M.H. Kramar, N. Vimolchalao, D. Hoffman, J. Caprioli; Detection of Visual Field Improvement After Trabeculectomy With Pointwise Linear Regression Analysis . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4000.
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© ARVO (1962-2015); The Authors (2016-present)
To detect visual field improvement after trabeculectomy with pointwise linear regression (PLR) analysis.
Series of reliable visual fields from 27 eyes of 27 patients who underwent trabeculectomy were studied retrospectively. At least three reliable visual fields before and three visual fields after surgery were required. PLR regression slopes were calculated to determine the direction of change for each visual field series. Criteria for classifying the change of each visual field series were at least one test location with a regression slope > 1 dB/year or < –1 dB/year and with p<0.05. To classify visual field series as worsening or improving after trabeculectomy, the number and direction of changing test locations were scored.
The average visual field Mean Defect (±SD) decreased after surgery from –8.8 (± 5.11) dB to –10.3 ([[Unsupported Character – Codename ­]]± 5.19) dB (p = 0.008). There was no significant change in the Pattern Standard Deviation (±SD) between the two groups: 6.7 (± 2.73) before trabeculectomy compared to 7.0 (± 2.39) after trabeculectomy (p=0.23). Considering only the test locations which fit the criteria for change, 16 eyes (59%) showed a significant change either before or after trabeculectomy. Of these 16 eyes, 8 eyes (29%) had improving visual field series after trabeculectomy.
Pointwise Linear Regression analysis can be used to identify visual field improvement after surgery, which is not a rare occurrence. The methods employed in this study could be applied to determine the success of trabeculectomy to help identify successful outcomes for glaucoma treatment.
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