Background:To evaluate the ability of scanning laser polarimetry with variable corneal compensation(GDx-VCC)in separating healthy fromglaucomatous patients with early visual field(VF)loss.Methods:Sixty-two healthy and...Background:To evaluate the ability of scanning laser polarimetry with variable corneal compensation(GDx-VCC)in separating healthy fromglaucomatous patients with early visual field(VF)loss.Methods:Sixty-two healthy and 48 glaucomatous age-matched patients with early glaucoma mean deviation(MD):-1.74dB ± 1.69 underwent complete ophthalmological evaluation,automated achromatic perimetry(AAP)and retinal nerve fiber layer(RNFL)measurement with GDx-VCC.One randomly selected eye from each subject was considered.Glaucomatous VF defects had either Glaucoma Hemifield Test(GHT)outside normal limits or pattern standard deviation(PSD)outside 95% confidence limits.Mean(± SD)MD,PSD and GDx-VCC parameters in the two groups were compared by t-test.For each GDx-VCC parameter,area under receiver operating characteristics(AUROC)curve and sensitivity at predetermined specificity ≥ 80% and ≥ 95% were calculated.Moreover,the parameter with largest AUROC was evaluated by likelihood ratios(LRs).Results:Mean values for MD,PSD and ten of 14 GDx-VCC parameters were significantly different between the two groups(P < 0.001).The three parameters with largest AUROCs were the nerve fiber indicator(NFI)(0.870),superior average(0.817)and normalized superior area(0.816)(P=0.08 for differences between AUROCs).NFI displayed sensitivity values of 80.2% and 60.4% for specificity ≥ 80% and ≥ 95%,respectively.At NFI cutoff value of 30,positive LR was 34.9(95% CI:4.9-247.6)and negative LR was 0.45(95% CI:0.32-0.61).Interval LRs showed large effect on post-test probability for NFI values ≤ 18 or ≥ 31.Conclusions:In our sample of eyes with early VF loss,GDx-VCC showed moderate-to-good discriminating ability.Among the best performing parameters,NFI had the largest AUROC,but several glaucomatous eyes(21,43.8%)had NFI< 30.This suggests that algorithm for NFI calculation requires some refinement when eyes with early VF loss are evaluated.展开更多
文摘Background:To evaluate the ability of scanning laser polarimetry with variable corneal compensation(GDx-VCC)in separating healthy fromglaucomatous patients with early visual field(VF)loss.Methods:Sixty-two healthy and 48 glaucomatous age-matched patients with early glaucoma mean deviation(MD):-1.74dB ± 1.69 underwent complete ophthalmological evaluation,automated achromatic perimetry(AAP)and retinal nerve fiber layer(RNFL)measurement with GDx-VCC.One randomly selected eye from each subject was considered.Glaucomatous VF defects had either Glaucoma Hemifield Test(GHT)outside normal limits or pattern standard deviation(PSD)outside 95% confidence limits.Mean(± SD)MD,PSD and GDx-VCC parameters in the two groups were compared by t-test.For each GDx-VCC parameter,area under receiver operating characteristics(AUROC)curve and sensitivity at predetermined specificity ≥ 80% and ≥ 95% were calculated.Moreover,the parameter with largest AUROC was evaluated by likelihood ratios(LRs).Results:Mean values for MD,PSD and ten of 14 GDx-VCC parameters were significantly different between the two groups(P < 0.001).The three parameters with largest AUROCs were the nerve fiber indicator(NFI)(0.870),superior average(0.817)and normalized superior area(0.816)(P=0.08 for differences between AUROCs).NFI displayed sensitivity values of 80.2% and 60.4% for specificity ≥ 80% and ≥ 95%,respectively.At NFI cutoff value of 30,positive LR was 34.9(95% CI:4.9-247.6)and negative LR was 0.45(95% CI:0.32-0.61).Interval LRs showed large effect on post-test probability for NFI values ≤ 18 or ≥ 31.Conclusions:In our sample of eyes with early VF loss,GDx-VCC showed moderate-to-good discriminating ability.Among the best performing parameters,NFI had the largest AUROC,but several glaucomatous eyes(21,43.8%)had NFI< 30.This suggests that algorithm for NFI calculation requires some refinement when eyes with early VF loss are evaluated.
