Comparison of immunoblotting (IgA and IgG) and the Goldmann-Witmer coefficient for diagnosis of ocular toxoplasmosis in immunocompetent patients.

BACKGROUND: Ocular toxoplasmosis (OT) is a common cause of posterior uveitis worldwide. The diagnosis of OT is based on clinical findings, but in most cases, laboratory tests are required to confirm the aetiology, especially when other diseases are suspected. The aim of this study was to evaluate which methods, between the Goldmann-Witmer coefficient (GWC) and immunoblotting (IB) with both IgG and IgA, in aqueous humour (AH) samples, can be the most sensitive to diagnose OT, in current practice, especially in the first three weeks. METHODS: Retrospectively reviewed records of 87 consecutive patients who had underwent AH and serum sample, 42 patients with suspected OT and 45 patients with suspected other ocular inflammatory diseases. All samples were analysed by both GWC and IB. RESULTS: The GWC was significant in 47.6% of patients presenting with suspected OT. The intraocular production of specific antibody anti-Toxoplasma gondii IgG and IgA was revealed by IB in 71.4% of samples. The combination of these two methods increased the sensitivity to 76.2%. Based on the interval between symptom onset and paracentesis, IB had a greater sensitivity than GWC when sample of AH was taken in the first three weeks (64.7% vs 23.5%, P=0.039), while the difference between the sensitivity of IB and GWC was less important in cases with an interval >3 weeks (76% vs 64% P=0.625). CONCLUSION: IB seems to be more useful than the GWC if only one of these methods can be performed, especially during the first three weeks after symptom onset.

Biometric evaluation of anterior chamber changes after physiologic pupil dilation using Pentacam and anterior segment optical coherence tomography.

PURPOSE: We evaluated changes in anterior chamber (AC) morphology and iris volume induced by physiological mydriasis in fellow eyes of acute angle-closure patients, and age-, sex-, and central AC depth-matched primary angle-closure suspects (PACS). METHODS: In our study, 21 fellow eyes of patients with acute angle closure; 40 age-, sex-, and central AC depth-matched PACS eyes; and 40 age- and sex-matched normal open-angle eyes were imaged using a Pentacam and anterior segment optical coherence tomography (AS-OCT) under light conditions, and after 5 minutes of darkness using AS-OCT. Iris volume was estimated using AS-OCT and a customized image-processing software. RESULTS: Central AC depth, corneal curvature, axial length, and lens thickness did not differ significantly between the PACS and fellow eyes. When going from light to dark, angle opening distance at 500 µm decreased significantly more in fellow eyes than in PACS (-68% vs. -52%, P < 0.001). When going from light to dark, the mean iris volume increased significantly in the fellow eyes (from 45.34 ± 2.1 to 47.68 ± 3.2 mm(3), P < 0.01), whereas it decreased significantly in most PACS eyes (from 45.01 ± 2.2 to 42.11 ± 2.3 mm(3), P < 0.01), and in all open-angle eyes (from 44.68 ± 1.16 to 41.67 ± 1.20 mm(3), P < 0.01). Based on multivariate analysis, significant predictors of angle narrowing under darkness (relative change in angle-opening distance 500) were fellow eyes compared to PACS (ß = -2.98, SE = 0.249, P = 0.005) and higher iris volume increase with pupil dilation (ß = -3.146, SE = 0.432, P = 0.015). CONCLUSIONS: Under dark conditions, angles of fellow eyes closed dramatically more than did those of PACS. Iris volume increase per millimeter of pupil dilation is an independent predictor of angle narrowing in darkness.

Biometric analysis of pigment dispersion syndrome using anterior segment optical coherence tomography.

PURPOSE: To compare anterior chamber volume (ACV), iris volume, and iridolenticular contact (ILC) area before and after laser peripheral iridotomy (LPI) in eyes with pigment dispersion syndrome (PDS) using anterior segment optical coherence tomography (AS OCT) and image processing software. DESIGN: Cross-sectional study. PARTICIPANTS: Eighteen eyes of 18 patients with PDS; 30 eyes of 30 controls matched for age, gender, and refraction. METHODS: Anterior segment OCT imaging was performed in all eyes before LPI and 1, 4, and 12 weeks after LPI. At each visit, 12 cross-sectional images of the AS were taken: 4 in bright conditions with accommodation (accommodation), 4 in bright conditions without accommodation (physiological miosis), and 4 under dark conditions (physiologic mydriasis). Biometric parameters were estimated using AS OCT radial sections and customized image-processing software. MAIN OUTCOME MEASURES: Anterior chamber volume, iris volume-to-length ratio, ILC area, AS OCT anterior chamber depth, and A-scan ultrasonography axial length. RESULTS: Before LPI, PDS eyes had a significantly greater ACV and ILC area than control eyes (P<0.01) and a significantly smaller iris volume-to-length ratio than the controls (P<0.05). After LPI, ACV and ILC area decreased significantly in PDS eyes, but iris volume-to-length ratio increased significantly (P<0.02) and was not significantly different from that of controls. These biometric changes were stable over time. Iris volume-to-length ratio decreased significantly from accommodation to mydriasis and from miosis to mydriasis, both in PDS and control eyes (P<0.01). In PDS eyes, ILC area decreased significantly from accommodation to mydriasis, both before and after LPI (P<0.01). On multivariate analysis, greater anterior chamber (AC) volume (P<0.02) and larger AC depth (P<0.05) before LPI were significant predictors of a larger ILC area. CONCLUSIONS: Pigment dispersion syndrome eyes do not have an iris that is abnormally large, relative to the AS size, but have a weakly resistant iris that is stretched and pushed against the lens when there is a pressure difference across the iris. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Structure-function relationships using spectral-domain optical coherence tomography: comparison with scanning laser polarimetry.

PURPOSE: To evaluate and compare the regional relationships between visual field sensitivity and retinal nerve fiber layer (RNFL) thickness as measured by spectral-domain optical coherence tomography (OCT) and scanning laser polarimetry. DESIGN: Prospective cross-sectional study. METHODS: One hundred and twenty eyes of 120 patients (40 with healthy eyes, 40 with suspected glaucoma, and 40 with glaucoma) were tested on Cirrus-OCT, GDx VCC, and standard automated perimetry. Raw data on RNFL thickness were extracted for 256 peripapillary sectors of 1.40625 degrees each for the OCT measurement ellipse and 64 peripapillary sectors of 5.625 degrees each for the GDx VCC measurement ellipse. Correlations between peripapillary RNFL thickness in 6 sectors and visual field sensitivity in the 6 corresponding areas were evaluated using linear and logarithmic regression analysis. Receiver operating curve areas were calculated for each instrument. RESULTS: With spectral-domain OCT, the correlations (r(2)) between RNFL thickness and visual field sensitivity ranged from 0.082 (nasal RNFL and corresponding visual field area, linear regression) to 0.726 (supratemporal RNFL and corresponding visual field area, logarithmic regression). By comparison, with GDx-VCC, the correlations ranged from 0.062 (temporal RNFL and corresponding visual field area, linear regression) to 0.362 (supratemporal RNFL and corresponding visual field area, logarithmic regression). In pairwise comparisons, these structure-function correlations were generally stronger with spectral-domain OCT than with GDx VCC and with logarithmic regression than with linear regression. The largest areas under the receiver operating curve were seen for OCT superior thickness (0.963 ± 0.022; P < .001) in eyes with glaucoma and for OCT average thickness (0.888 ± 0.072; P < .001) in eyes with suspected glaucoma. CONCLUSIONS: The structure-function relationship was significantly stronger with spectral-domain OCT than with scanning laser polarimetry, and was better expressed logarithmically than linearly. Measurements with these 2 instruments should not be considered to be interchangeable.