G. Hollo

Comparison between fixed-angle and customised corneal-polarisation compensation methods in scanning laser polarimetric measurement of the retinal nerve fibre layer in glaucoma

AbstractPurposeTo investigate the differences between the results of scanning laser polarimetric (SLP) measurements of the retinal nerve fibre layer thickness (RNFLT) made using two different corneal-polarisation techniques; customised (SLP-C), and fixed-angle (SLP-F) compensations.MethodsBoth SLP-C and SLP-F were performed on 37 consecutive phakic patients with chronic open-angle glaucoma, and on 14 healthy control subjects. One randomly selected eye per subject was evaluated.ResultsBoth SLP-C and SLP-F parameters were able to discriminate between the glaucoma group and the control group, except in the case of the ellipse modulation, which differed significantly between the two groups with SLP-C (P=0.017), but not with SLP-F (P=0.056). When SLP-C and SLP-F values were compared, inferior maximum thickness and ellipse standard deviation were significantly lower with SLP-C in both groups (P<0.05 for each parameter). Superior maximum thickness was significantly lower in glaucoma with SLP-C than with SLP-F (P=0.006) and tended to be lower with SLP-C than with SLP-F in the control group (P=0.053). In the glaucoma group, it was only with SLP-C that a significant (positive) correlation between the superior maximum thickness and the inferior hemifield mean sensitivity (MS) (r=0.653, P<0.001), and between the inferior maximum thickness and the superior hemifield MS (r=0.420, P=0.023) was found. The other global and sectoral SLP parameters showed significant correlation with the corresponding visual field parameters with both techniques.ConclusionOur findings suggest that SLP measurements with customised compensation provide more realistic results for RNFLT than those made with the conventional fixed-angle compensation.

Influence of subfoveal choroidal neovascularisation on macular imaging with scanning laser polarimetry of the retinal nerve fibre layer.

AbstractPurposeTo investigate the influence of subfoveal choroidal neovascularisation (CNV) on macular imaging performed using scanning laser polarimetry (SLP) of the retinal nerve fibre layer.MethodsSLP was performed on 22 consecutive patients with angiographically verified CNV, and on 23 healthy control subjects. One eye per subject was evaluated using the GDx Nerve Fibre Analyser. Regularity of the corneal retardation on the macular SLP images was assessed according to three criteria: (1) magnitude of the ‘macular ratio’, defined as the ratio of mean retardation values along two axes (the axis with the maximum retardation and the perpendicular one, corresponding in healthy eyes to minimum retardation); (2) the values of GDx parameters which are independent of quadrant position (ellipse modulation and ellipse average); and (3) the frequency of the regular ‘bow–tie’ polarisation pattern.Results‘Macular ratio’ was significantly higher in the CNV group than in the control group (P≪0.001). Ellipse modulation did not differ between the groups, but ellipse average was higher in the CNV group (P=0.016). The variance for each of these two parameters was significantly higher for the CNV group (P≪0.001 for both comparisons). A ‘bow–tie’ pattern polarisation was seen in 23 of the 23 control eyes, but only in 7 of the 22 CNV eyes (P≪0.001).ConclusionThe results show that CNV influences the macular image obtained with SLP. This suggests that measurements with SLP may be disturbed for eyes with CNV when the customised corneal compensation method, which makes use of the macular retardation image, is employed.

Health anxiety in a non-population-based, pre-publicised glaucoma screening exercise

ObjectiveTo investigate whether anxiety plays a role in self-recruitment for non-population-based glaucoma screening.MethodsIn a non-population-based pre-publicised trial, self-recruited Caucasian participants were screened for glaucoma, and also completed the Trait Anxiety Inventory and Shortened Health Anxiety Inventory questionnaires. In pre-publicity for the trial, information on risk factors for glaucoma was given. Participants classified as possible glaucoma cases later underwent a detailed glaucoma investigation.ResultsOf the 120 total participants (72 females, 48 males), 12 were considered glaucoma suspects at the screening, although only three (2.5%) were ultimately diagnosed with glaucoma. Health anxiety showed significant correlation with trait anxiety (r=0.525, P<0.001). Trait anxiety was similar for both the genders; this score was significantly below the normal Hungarian population value in women (P<0.001) and at the normal population level in men (P=0.560). In contrast, health anxiety was significantly higher than for both the ‘normal’ and ‘anxious’ reference groups (P<0.001), although smaller than that for hypochondriacs (P<0.001). Participants with pre-existing ocular symptoms, and those who attended because of fear of blindness, had significantly higher trait- and health-anxiety scores (P<0.05 for all comparisons).ConclusionIn this screening trial, the health anxiety of the self-recruited participants was significantly above normal, whereas the prevalence of glaucoma was within the usual range for a Caucasian population. This suggests that providing pre-publicity information on risk factors for glaucoma does not necessarily increase the prevalence of glaucoma among self-recruited participants in non-population-based screening, as some individuals may participate on account of elevated health anxiety, rather than because of higher potential risk for glaucoma.