Diagnostic accuracy of nerve fibre layer, macular thickness and optic disc measurements made with the RTVue-100 optical coherence tomograph to detect glaucoma.

PURPOSE: To evaluate the diagnostic accuracy of retinal nerve fibre layer thickness (RNFLT), ganglion cell complex (GCC), and optic disc measurements made with the RTVue-100 Fourier-domain optical coherence tomography (OCT) to detect glaucoma in a Caucasian referral population. METHODS: One randomly selected eye of 286 Caucasian patients (93 healthy, 36 ocular hypertensive, 46 preperimetric glaucoma, and 111 perimetric glaucoma eyes) was evaluated. RESULTS: Using the software-provided classification, for the total population sensitivity did not exceed 73.6% for the optic nerve head parameters, and 62.7% for the other parameters. Specificity was high (94.6-100%) for most RNFLT and GCC parameters, but low (72.0-76.3%) for the optic disc parameters. Positive predictive value varied between 98.1 and 100% for the main RNFLT parameters, 92.6 and 100% for the 16 RNFLT sectors, 92.4 and 99.0% for the GCC parameters, but did not exceed 86.3% for any of the optic disc parameters. Positive likelihood ratio (PLR) was higher than 10 for average, inferior and superior RNFLT (25.5 to infinite), 12 of the 16 RNFLT sectors (12.6 to infinite), and three of the four GCC parameters (40.0 to 48.6). No optic disc parameter had a PLR higher than 3.0. CONCLUSIONS: RNFLT and GCC parameters of the RTVue-100 Fourier-domain OCT showed moderate sensitive but high specificity, positive predictive value and PLR for detection of glaucoma. The optic disc parameters had lower diagnostic accuracy than the RNFLT and GCC parameters.

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

OBJECTIVE: To investigate whether anxiety plays a role in self-recruitment for non-population-based glaucoma screening. METHODS: In 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. RESULTS: Of 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). CONCLUSION: In 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.

Mean intraocular pressure and progression based on corneal thickness in patients with ocular hypertension.

PURPOSE: To determine the incidence of glaucomatous progression at mean intraocular pressure (IOP) levels in patients with ocular hypertension (OHT). METHODS: A retrospective, multicentre, cohort analysis of 230 OHT patients with 5 years of follow-up evaluated for risk factors associated with progressive optic disc and visual field loss to determine the incidence of glaucomatous progression. RESULTS: Forty percent of patients with IOPs > or = 24 mmHg, 18% of patients with IOPs of 21-23 mmHg, 11% of patients with IOPs with 18-20 mmHg, and 3% of patients with IOPs of < or = 17 mmHg progressed to glaucoma. The mean IOP was 19.8+/-2.4 mmHg in the stable group and 21.7+/-2.6 mmHg in the progressed group (P=0.0004). The highest average peak IOP was 23.4+/-4.0 mmHg in the stable group and 25.2+/-3.1 mmHg in the progressed group (P=0.006). Based on the pachymetry values for central corneal thickness, patients with thinner corneas more often progressed to glaucoma (P<0.0001). A multivariant regression analysis to determine risk factors for progression was positive primarily for higher peak IOPs, older age, male gender, argon laser trabeculoplasty, visual acuity > or = 20/50, and no topical medical therapy or beta-blocker therapy prior to the study. CONCLUSIONS: IOP reduction within the normal range over 5 years of follow-up reduces the chance of progression to primary open-angle glaucoma in OHT patients.

Long-term progression at individual mean intraocular pressure levels in primary open-angle and exfoliative glaucoma.

PURPOSE: To describe progression and non-progression rates at individual mean intraocular pressure (IOP) levels for patients with primary open-angle and exfoliative glaucoma. METHODS: A meta-analysis of five previously published retrospective studies describing progression and non-progression rates at individual intraocular pressure levels over 5 or more years of follow-up. All patients had primary open-angle (four studies) or exfoliative glaucoma (one study). RESULTS: This meta-analysis included 822 patients of whom 655 (80%) had primary openangle glaucoma and 167 (20%) had exfoliative glaucoma. In total, 220 patients progressed (27%), while 602 (73%) remained stable over 5 years. The mean IOP was 20.0 for progressed and 17.1 mmHg for stable patients (p=0.0004). The peak IOP was 29.1 for progressed and 23.6 mmHg for stable patients (p=0.0014). At an IOP level >18 mmHg, 49% of patients remained stable; at 18 mmHg, 78%; between 13 and 17 mmHg, 82%; and <13 mmHg, 96%. Additional factors associated with progression were older age (p=0.0004) and exfoliative glaucoma (p=0.0001). However, multivariant regression analysis identified only mean IOP as a risk factor for progression (p=0.039). CONCLUSIONS: This study suggests that maintaining an IOP well within the normal range over 5 years in patients with primary open-angle or exfoliative glaucoma helps to prevent glaucomatousprogression.

A combined artificial chromosome-stem cell therapy method in a model experiment aimed at the treatment of Krabbe's disease in the Twitcher mouse.

Mammalian artificial chromosomes (MACs) are safe, stable, non-integrating genetic vectors with almost unlimited therapeutic transgene-carrying capacity. The combination of MAC and stem cell technologies offers a new strategy for stem cell-based therapy, the efficacy of which was confirmed and validated by using a mouse model of a devastating monogenic disease, galactocerebrosidase deficiency (Krabbe's disease). Therapeutic MACs were generated by sequence-specific loading of galactocerebrosidase transgenes into a platform MAC, and stable, pluripotent mouse embryonic stem cell lines were established with these chromosomes. The transgenic stem cells were thoroughly characterized and used to produce chimeric mice on the mutant genetic background. The lifespan of these chimeras was increased twofold, verifying the feasibility of the development of MAC-stem cell systems for the delivery of therapeutic genes in stem cells to treat genetic diseases and cancers, and to produce cell types for cell replacement therapies.

Diurnal IOP control with bimatoprost versus latanoprost in exfoliative glaucoma: a crossover, observer-masked, three-centre study.

AIM: To evaluate the diurnal intraocular pressure (IOP) control and safety of bimatoprost versus latanoprost in exfoliative glaucoma (XFG). METHODS: One eye of 129 consecutive patients with XFG (mean (SD) age 66.5 (8.3) years) was included in this prospective, observer-masked, three-centre, crossover comparison. After a 4-6 week medicine-free period patients were randomised to bimatoprost or latanoprost monotherapy for 3 months. Patients were then switched to the opposite treatment for another 3 months. At the end of the washout and the treatment periods diurnal IOP was measured at 0800, 1300, and 1800. RESULTS: At baseline the IOP (mean (SD)) was 28.0 (4.0), 26.9 (3.6), and 25.9 (3.6) mm Hg, at the three time points, respectively. Both treatments significantly reduced mean diurnal IOP at month 3. Mean diurnal IOP was 26.9 (3.5) mm Hg at baseline, 17.6 (3.3) mm Hg with bimatoprost, and 18.6 (3.6) mm Hg with latanoprost (p<0.0001). Furthermore, lower IOP values were obtained with bimatoprost at all time points (17.9 (3.4), 17.3 (3.3), and 17.6 (3.5) mm Hg, respectively) compared with latanoprost (18.7 (3.6), 18.5 (3.6), and 18.6 (4.1) mm Hg, respectively). The corresponding mean differences (0.8, 1.1, and 1.0 mm Hg, respectively) were all significant (p<0.001 for each comparison). Significantly more patients with XFG obtained a target diurnal IOP <17 mm Hg with bimatoprost than with latanoprost, 55/123 (45%) v 34/123 (28%); (p = 0.001), and significantly fewer patients were non-responders with bimatoprost than with latanoprost (5 v 13, p = 0.021). More patients reported at least one adverse event with bimatoprost than with latanoprost (58 v 41 at 3 months; p = 0.0003). CONCLUSION: This crossover study suggests that better diurnal IOP control is obtained with bimatoprost than with latanoprost in patients with XFG.

The efficacy and safety of timolol maleate versus brinzolamide each given twice daily added to travoprost in patients with ocular hypertension or primary open-angle glaucoma.

PURPOSE: To compare the efficacy and safety of timolol maleate 0.5% versus brinzolamide 1% when added to travoprost 0.004% in patients with ocular hypertension or primary open-angle glaucoma. DESIGN: A prospective, double-masked, randomized, active-controlled, parallel comparison. METHODS: Qualified patients at Visit 1 were placed on travoprost dosed every evening for 4 weeks and then were randomized at baseline (Visit 2) to the addition of timolol maleate or brinzolamide each given twice daily. Patients returned to clinic at Week 4 (Visit 3) for a safety visit and Week 12 (Visit 4) for an efficacy visit. At Visits 2 and 4 the intraocular pressure (IOP) was measured at 08:00, 12:00, and 16:00 hours. RESULTS: Ninety-seven patients on brinzolamide had a baseline diurnal IOP of 21.5+/-2.2 mmHg and 95 on timolol maleate had 21.3+/-2.5 mmHg, each added to travoprost. The diurnal mean IOP at Week 12 was 18.1+/-2.7 mmHg for brinzolamide and 18.1+/-3.0 mmHg for timolol maleate (p=0.96). There was no statistical difference found between treatment groups in the absolute level of pressure, or in the reduction in IOP from baseline, at each time point or for the diurnal curve (p>0.05). There was no significant difference for any adverse event between groups (p>0.05), with the most common side effect being conjunctival hyperemia in 15/97 (16%) brinzolamide and 6/95 (6%) timolol treated patients (p=0.06). CONCLUSIONS: This study showed that brinzolamide provides similar safety and efficacy compared to timolol maleate when added to travoprost.

Increase of carotid artery stiffness and decrease of baroreflex sensitivity in exfoliation syndrome and glaucoma.

AIM: To investigate the distensibility of the common carotid artery (CCA), baroreflex sensitivity (BRS) and its relation to plasma homocysteine concentration in exfoliation syndrome or exfoliation glaucoma (XFS/XFG). METHODS: Homocysteine concentrations were measured in 30 XFS/XFG patients and 18 age matched controls. In 21 patients and 17 controls the end diastolic diameter of the CCA and pulsatile distension were measured and BRS was calculated. RESULTS: There was no significant difference between the groups in sex distribution, age, heart rate, blood pressure, systemic diseases, or medication. In XFS/XFG patients homocysteine concentration was significantly elevated (unpaired t test, p = 0.023), and CCA stiffness was higher (p<0.05), while strain, cross sectional compliance coefficient, distensibility, and BRS were significantly reduced compared to the controls (Mann-Whitney U test, p< or =0.013 for each parameter). In XFS/XFG patients a positive correlation was found between age and plasma homocysteine level (Pearson's correlation, r = 0.490, p = 0.007), and a negative correlation between age and BRS (Kendall's correlation r = -0.374, p = 0.021), as well as between homocysteine concentration and BRS (Kendall's correlation r = -0.377, p = 0.024). No correlation was seen between these variables in the control group. CONCLUSIONS: These results suggest a pathological large artery function as well as altered parasympathetic vascular control in XFS/XFG which increases with age and with higher homocysteine concentration.

Presentation and long-term follow-up of exfoliation glaucoma in Greece, Spain, Russia, and Hungary.

PURPOSE: To evaluate clinical presentation and long-term follow-up of exfoliation glaucoma in separate European population groups. METHODS: A four-center, retrospective, case series analysis in which 200 charts of patients with exfoliation glaucoma or patients with elevated intraocular pressure (IOP) associated with exfoliation syndrome in at least one eye with at least 5 years of follow-up were consecutively reviewed. RESULTS: This study found an average follow-up time of 6.0+/-2.1 years. Patients in Hungary and Spain statistically presented at an older age (79 years) than Greek patients (67 years). Patients with exfoliation glaucoma in Greece and Hungary had more glaucomatous damage, had more severe glaucoma, had a higher untreated IOP (31.8 to 32.1 mmHg), and were more difficult to control, showing a greater number of changes in medicines during the follow-up period, a greater number of medicines at the end of the follow-up period, and more progression. On long-term follow-up, Greek, Russian, and Hungarian patients also had the highest mean IOP (18.8 to 20.8 mmHg) and the greatest incidence of progression (approximately 50%). Spanish patients demonstrated the lowest mean IOP (17.6+/-3.6 mmHg) and the lowest rate of progression (28%) during the follow-up period and the fewest number of medications per patient (0.7) to control the IOP at the end of the follow-up period. CONCLUSIONS: The severity of exfoliation glaucoma presentation and its course may differ within distinct geographic populations in Europe.

Correlation between polarimetric retinal nerve fiber layer thickness and retinal sensitivity determined with frequency-doubling technology.

BACKGROUND AND OBJECTIVE: Correlation between polarimetric retinal nerve fiber layer thickness measured with variable corneal compensation and retinal sensitivity measured with frequency-doubling technology (FDT) and standard automated perimetry (SAP) was investigated. PATIENTS AND METHODS: Twenty-four consecutive patients with chronic open-angle glaucoma and 17 healthy control subjects (1 randomly selected eye for each subject) were evaluated. RESULTS: For all subjects, quadrant scanning laser polarimetry parameters correlated positively with both FDT and SAP mean sensitivity of the opposite hemifield (P< .001). Global scanning laser polarimetry parameters correlated positively with FDT-mean sensitivity, SAP-mean sensitivity, and FDT-mean deviation, and negatively with SAP-mean deviation (in SAP, mean deviation is positive in case of sensitivity loss) (P < or = .02). The nerve fiber indicator also correlated with FDT-pattern standard deviation and SAP-corrected loss variance (P < or = .01). Using un-logged sensitivity values, no further correlations were found. CONCLUSION: Our results show that a similar structure-function relationship exists between polarimetric retinal nerve fiber layer thickness determined with variable corneal compensation and retinal sensitivity measured with SAP and FDT.

Enhanced corneal compensation for scanning laser polarimetry on eyes with atypical polarisation pattern.

AIM: To investigate the potential advantage of an enhanced corneal compensation algorithm (ECC) compared with variable corneal compensation (VCC) in the analysis of scanning laser polarimetric (SLP) images with atypical retardation pattern (ARP). METHODS: SLP-VCC images with ARP (typical scan score (TSS) <80) of one eye of each of 27 glaucoma patients and 19 healthy subjects were compared with the corresponding SLP-ECC images obtained at the same session. RESULTS: ARP was present in 10.4% of the normals and 15.5% of the glaucoma patients imaged with SLP-VCC over 9 months. In both groups TSS was higher for ECC than for VCC (p<0.001). In glaucoma TSNIT, superior and inferior average thickness values were significantly lower, and TSNIT (measuring ellipse around the optic nerve head in the four (temporal, superior, nasal, inferior) quadrants) standard deviation was significantly higher with ECC than with VCC (p<0.001). In the normal group nerve fibre indicator (NFI) was lower with ECC than with VCC (p=0.007). TSNIT average was smaller and TSNIT standard deviation was higher with ECC (p<0.001). Superior and inferior average thickness did not differ between VCC and ECC in the normal group. CONCLUSIONS: The new ECC software substantially improves polarimetric image analysis on eyes showing atypical polarisation pattern.

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

PURPOSE: To investigate the influence of subfoveal choroidal neovascularisation (CNV) on macular imaging performed using scanning laser polarimetry (SLP) of the retinal nerve fibre layer. METHODS: SLP 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). CONCLUSION: The 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.

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

PURPOSE: To 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. METHODS: Both 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. RESULTS: Both 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. CONCLUSION: Our findings suggest that SLP measurements with customised compensation provide more realistic results for RNFLT than those made with the conventional fixed-angle compensation.

Scanning laser polarimetry of retinal nerve fibre layer thickness after laser assisted in situ keratomileusis (LASIK): stability of the values after the third post-LASIK month.

BACKGROUND: Monitoring the retinal nerve fibre layer thickness (RNFLT) is essential in the diagnosis and treatment of glaucoma. In a previous study we found that a decrease of the polarimetric RNFLT observed in the early period after laser-assisted in situ keratomileusis (LASIK) disappears or tends to disappear by the third post-LASIK month. PURPOSE: To study the stability of the "recovered" polarimetric retardation values between the third and twelfth month after LASIK. METHODS: Scanning laser polarimetry (SLP) with the classic GDx Nerve Fiber Analyzer was performed on 13 consecutive healthy subjects with no eye disease who underwent LASIK for ametropia correction. Measurements were performed preoperatively, then at 3 and 12 months postoperatively. RESULTS: Inferior, temporal and nasal average thickness as well as ellipse average thickness and average thickness showed no difference among the three time points (ANOVA, p > 0.05). Superior average thickness was significantly smaller both at three months (Sheffe test, p =0.008) and 12 months (p =0.006) than before LASIK. However, no difference was seen between the values measured at three months and at 12 months after LASIK (p =0.997). A statistically significant interaction between treatment type (myopic or hyperopic correction) and the change of retardation was found for the superior average thickness (two-way ANOVA, p =0.016). In this quadrant the RNFLT values of the myopic eyes decreased between the baseline and the month 3 measurements but became stable after that; the retardation of the hyperopic eyes remained unchanged throughout. CONCLUSION: RNFLT measured with the classic GDx device after LASIK shows transient changes probably due to the LASIK-induced alteration of the polarization and the healing process. The polarimetric RNFLT values, however, become stable by the third post-LASIK month, and show no further change until the end of the first year after LASIK. Baseline SLP measurements for long-term glaucoma follow-up can be obtained from the third post-LASIK month onwards.

Endothelin-1 concentration is increased in the aqueous humour of patients with exfoliation syndrome.

BACKGROUND: /aim: Endothelin 1 (ET-1) is considered the most potent vasoconstrictor in the body and the eye. This molecule may play a significant role in the pathobiology of exfoliation syndrome (XFS), a disorder characterised by a progressive iris vasculopathy. The purpose of this study was to investigate the concentration of ET-1 in the aqueous humour of cataract patients with and without XFS. METHODS: Aqueous humour samples were obtained from 25 consecutive eyes of 25 cataract patients with XFS and an equal number of age matched controls during phacoemulsification cataract surgery. None of the subjects had elevated intraocular pressure or glaucoma. ET-1 concentration in the aqueous was measured using a specific immunoassay with 100% immunoreactivity for ET-1. Total aqueous humour protein concentration was measured with a microplate Coomassie blue based method and was correlated with ET-1 concentration. RESULTS: Mean ET-1 concentration in the XFS aqueous samples (4.6 (SD 2.3) pg/ml) was significantly higher than that measured in the age matched control samples (2.8 (SD 1.71) pg/ml); (p = 0.006). Although total protein concentration was significantly elevated in the XFS samples (0.380 (SD 0.159) v 0.279 (SD 0.144) mg/ml in the controls); (p = 0.023), no correlation was found between aqueous ET-1 and total protein concentration (p = 0.730). CONCLUSION: The increased concentration of ET-1 in the aqueous humour of XFS patients suggests that ET-1 may play a role in the pathobiology of XFS.

Influence of LASIK on scanning laser polarimetric measurement of the retinal nerve fibre layer with fixed angle and customised corneal polarisation compensation.

BACKGROUND/AIM: Retinal nerve fibre layer thickness (RNFLT), as measured with scanning laser polarimetry using the fixed angle corneal polarisation compensator (SLP-F), has been found to be reduced after uncomplicated laser assisted in situ keratomileusis (LASIK) compared to the pre-LASIK measurement. Since this virtual RNFLT thinning is attributed to the corneal changes induced by the LASIK, the authors investigated whether customised corneal polarisation compensation (SLP-C), which compensates for the actual corneal polarisation during each measurement, can avoid the LASIK induced, virtual changes of the polarimetric RNFLT values. METHODS: Scanning laser polarimetry using both the SLP-F and SLP-C methods (GDx-Access, software version 5.0) was performed on 15 consecutive healthy subjects with no eye disease who underwent LASIK for ametropia correction. The SLP measurements were performed before the surgery, then on day 1 and day 6 after LASIK. Thickness data from images of one randomly selected eye per subject were analysed using the ANOVA and Scheffe multiple comparison tests. RESULTS: Superior maximum, inferior maximum, normalised superior area, and normalised inferior area (SLP parameters representing the RNFLT at the superior and inferior poles of the optic nerve head) remained unchanged with SLP-C (ANOVA, p>0.05) but decreased (superior maximum, normalised superior area, Scheffe test, p<0.05) or tended to decrease (inferior maximum) after LASIK, when measured using SLP-F. In contrast, certain other parameters-namely, superior ratio and inferior ratio (representing the ratios between the superior or the inferior sector and the temporal sector), maximal modulation, and ellipse modulation decreased with SLP-C (Scheffe test, p<0.05), but remained stable with SLP-F (ANOVA, p>0.05) after LASIK. Superior to nasal ratio, symmetry of the superior and inferior RNFLT as well as the parameter showing the probability of having glaucoma (called "the number") remained unchanged with both types of corneal compensation (ANOVA, p>0.05). With SLP-C the parameter ellipse average thickness increased after LASIK (Scheffe test, p = 0.021). No parameter value altered between day 1 and day 6 after LASIK, for either method. CONCLUSION: The results suggest that the LASIK induced decrease of the polarimetric RNFLT, which is consistently detected with polarimeters when using the fixed angle corneal polarisation compensator, is due to alterations of the corneal polarisation. The use of customised corneal polarisation compensation avoids this virtual decrease of the polarimetric RNFLTHowever, our results suggest an increase of the measured retardation in the temporal quadrant of the SLP-C image after LASIK. Since ratios of parameters using the temporal RNFLT in the denominator are important in the polarimetric glaucoma diagnosis algorithm, their decrease as a consequence of using SLP-C needs further investigation.

8-Isoprostaglandin F2a and ascorbic acid concentration in the aqueous humour of patients with exfoliation syndrome.

BACKGROUND/AIMS: The authors investigated the concentrations of 8-isoprostaglandin F(2a), a marker of oxidative stress in vivo, and ascorbic acid, a protectant against oxidative damage, in the aqueous humour of patients with exfoliation syndrome (XFS) and cataract and compared the results with those in age matched patients with cataract, but without XFS, to determine whether XFS is associated with increased oxidative stress. METHODS: Aqueous humour was aspirated at the beginning of phacoemulsification cataract surgery from 27 eyes of 27 cataract patients with XFS and 27 eyes of 27 age matched cataract patients without XFS. 8-Isoprostaglandin F(2a)concentration in the aqueous was determined with a commercial immunoassay; ascorbic acid concentration was measured with a microplate assay method. RESULTS: The mean concentration of 8-isoprostaglandin F(2a)in the aqueous from patients with XFS (2429 (SD 2940) pg/ml; range 400-10500 pg/ml) was significantly higher than that measured in the aqueous of age matched control patients (529.1 (226.8) pg/ml; range 325-1000 pg/ml); (p = 0.0028). Furthermore, mean ascorbic acid concentration in XFS patients (0.75 (0.39) mM; range 0.28-1.70 mM) was significantly lower than that found in control patients (1.19 (0.47) mM; range 0.53-2.4 mM); (p = 0.0005). There was a reverse correlation between 8-isoprostaglandin F(2a)and ascorbic acid concentration. CONCLUSION: 8-Isoprostaglandin F(2a)was significantly increased in the aqueous of patients with XFS, and ascorbic acid was decreased, providing evidence of a role for free radical induced oxidative damage in the pathobiology of XFS.

Influence of post-LASIK corneal healing on scanning laser polarimetric measurement of the retinal nerve fibre layer thickness.

AIM: To investigate the influence of laser assisted in situ keratomileusis (LASIK) on the values for retinal nerve fibre layer thickness (RNFLT) as measured with scanning laser polarimetry (SLP) during the healing process of the cornea after LASIK. METHODS: SLP with the GDx instrument was performed on 20 consecutive healthy subjects without any eye disease undergoing LASIK for ametropia correction. The SLP measurements were performed before the surgery, and at 1 and 3 days, as well as at 3 months, after LASIK. Thickness data from images of one randomly selected eye per subject were analysed using the ANOVA and Duncan multiple comparison tests. Correlation coefficients between RNFLT data and the treatment parameters were also calculated. RESULTS: Somewhat similar results were found for the different retinal areas. The measured values for superior average RNFLT decreased significantly at all time points compared to the preoperative baseline (p<0.003, Duncan test), but increased significantly between postoperative day 1 and the final visit at 3 months (p=0.025, Duncan test). Inferior average RNFLT in the early postoperative days was significantly smaller than at 3 months after LASIK (p<0.05, Duncan test), and tended to be smaller than at baseline. The thickness values before surgery and at the final visit, however, showed no significant difference (p=0.698, Duncan test) in this region. Ellipse average RNFLT was significantly smaller in the early postoperative days than the baseline value before LASIK. However, the measured value had significantly increased again by the time of the final visit (p<0.02, Duncan test). This value at the final visit showed no difference from the baseline value (p=0.46, Duncan test). The changes in the nasal average and temporal average RNFLT were not statistically significant. No correlation was found between the change in the SLP measured thickness values and central corneal thickness at baseline and its change after surgery, nor with the change in cylindrical correction due to LASIK, or the length of the suction time during surgery (p>0.05 for all correlations). CONCLUSION: The SLP technique is sensitive to the corneal optical properties, and RNFLT as measured with SLP shows changes after LASIK. Most of these changes, however, diminish with time after surgery, and the values tend to return to the preoperative results during the first 3 months of corneal healing following uncomplicated LASIK. It appears that in uncomplicated cases the transient RNFLT changes are artefacts and do not imply pathological thickness alterations due to LASIK.