Long-term visual pathway alterations after elemental mercury poisoning: report of a series of 29 cases.

BACKGROUND: There are few clinical data on retinal involvement after acute exposure to high concentrations mercury and the available reports are based on a small number of patients suffering chronic exposure. The purpose of this paper is to report findings in workers acutely exposed to very high concentrations of mercury vapor with the aim of providing data on a possible direct retinal involvement. METHODS: Twenty-nine patients and 16 controls were evaluated in a comparative case series. Mercury levels in blood and urine samples, visual acuity (VA), contrast sensitivity (CS), visual field (VF), color discrimination and optical coherence tomography (OCT) were recorded. The pattern reversal visual-evoked potentials (PRVEP), full-field and multifocal electroretinography (ffERG/mfERG), pattern electroretinography (PERG), systemic symptoms, presence of erethism, and electromyography (EMG) were also gathered. A descriptive analysis was performed. The correlations between variables also were studied. In addition, electrophysiological data from those patients with deeper VF defects (group 1) were compared with a normal control group. RESULTS: Twenty-six workers exhibited symptoms of erethism. The EMG showed sensorimotor polyneuropathy and multiple mononeuropathy. The VA was slightly affected in 48.27% (n = 14) of subjects. Loss of CS in at least one of four spatial frequencies and color vision alterations occurred in 96.5% (n = 28) and 44.8% (n = 13), respectively. VF alterations were identified in 72.4% (n = 21) patients. No morphologic changes were seen in the OCT scans. Latencies over 100 milliseconds and reduced amplitudes of P100 were found in the PRVEP (p < 0.05). The reduced amplitude of the b wave at the ffERG, of the P50 at the PERG and of the P1 wave at the mfERG results (p < 0.05) suggested that the outer retina was involved. Significant negative correlations among blood mercury levels, VA, and ffERG were observed. CONCLUSIONS: In this case series, showed that acute exposure to mercury vapor had a hazardous effect on the visual system. Although neurologic and visual pathway involvement was clearly demonstrated, the differences found compared to control support the existence of a direct functional retinal damage and participation in impaired vision in mercury poisoning.

Ocular Surface Pathology in Patients Suffering from Mercury Intoxication.

PURPOSE: To report the ocular surface pathology of patients suffering from acute/subacute mercury vapor intoxication. DESIGN: Cross-sectional study. PARTICIPANTS: Male workers intoxicated with inorganic mercury referred for ophthalmic involvement and healthy control subjects. METHODS: The following tests were performed: dry eye (DE)-related symptoms indicated by the ocular surface disease (OSDI) index questionnaire; tear osmolarity; analysis of 23 tear cytokine concentrations and principal component and hierarchical agglomerative cluster analyses; tear break-up time (T-BUT); corneal fluorescein and conjunctival lissamine green staining; tear production by Schirmer and tear lysozyme tests; mechanical and thermal corneal sensitivity (non-contact esthesiometry); and corneal nerve analysis and dendritic cell density by in vivo confocal microscopy (IVCM). RESULTS: Twenty-two out of 29 evaluated patients entered the study. Most had DE-related symptoms (OSDI values > 12), that were severe in 63.6% of them. Tear osmolarity was elevated (>308 mOsms/L) in 83.4% of patients (mean 336.23 (28.71) mOsm/L). Corneal and conjunctival staining were unremarkable. T-BUT was low (<7 s) in 22.7% of patients. Schirmer test and tear lysozyme concentration were low in 13.6% and 27.3% of cases, respectively. Corneal esthesiometry showed patient mechanical (mean 147.81 (53.36) mL/min) and thermal thresholds to heat (+2.35 (+1.10) °C) and cold (-2.57 (-1.24) °C) to be significantly higher than controls. Corneal IVCM revealed lower values for nerve density (6.4 (2.94) n/mm2), nerve branching density (2 (2.50) n/mm2), and dendritic cell density (9.1 (8.84) n/mm2) in patients. Tear levels of IL-12p70, IL-6, RANTES, and VEGF were increased, whereas EGF and IP-10/CXCL10 were decreased compared to controls. Based on cytokine levels, two clusters of patients were identified. Compared to Cluster 1, Cluster 2 patients had significantly increased tear levels of 18 cytokines, decreased tear lysozyme, lower nerve branching density, fewer dendritic cells, and higher urine mercury levels. CONCLUSIONS: Patients suffering from systemic mercury intoxication showed symptoms and signs of ocular surface pathology, mainly by targeting the trigeminal nerve, as shown by alterations in corneal sensitivity and sub-basal nerve morphology.

Clinical Features and Prognostic Factors in Presumed Ocular Tuberculosis.

PURPOSE: To characterize the clinical features in patients with presumed ocular tuberculosis (TB) and determine prognostic factors of visual outcomes and complications in this disease. MATERIAL AND METHODS: Retrospective case series of 35 patients (29 females, 6 males) with presumed ocular TB from referral centers in Chile and Spain between 2002 and 2012. Medical records were reviewed, and data regarding clinical features, complications, best-corrected visual acuity (BCVA), duration of disease, extraocular manifestations, and therapy were retrieved. Prognostic factors for low vision (BCVA 20/50 or less), legal blindness (BCVA 20/200 or less), and complications (cataract, glaucoma, and macular lesion) were evaluated. To calculate correlations, we used Spearman's rank correlation test. To determine clinical predictors, we used the binary logistic regression test. RESULTS: Anterior and non-granulomatous uveitis was the most common types of inflammation. Only 2 (5.7%) patients had respiratory symptoms, and 6 (17.1%) patients had an abnormal chest X-ray at diagnosis. All patients received combined antitubercular therapy with a mean duration of 6.9 ± 2.3 months. A longer duration of symptoms at diagnosis was associated with both low vision and legal blindness. Older patients had a higher risk of legal blindness. A longer duration of symptoms as well as anterior inflammation demonstrated an increased risk for cataract formation. The duration of the symptoms and baseline BCVA had a positive correlation with the final BCVA. Prognostic factors of macular lesions were not found. CONCLUSIONS: The diagnosis of ocular TB can be difficult due to the lack of extraocular manifestations and the broad spectrum of ocular features. A longer duration of symptoms at diagnosis was associated with poorer visual outcomes and cataracts. Therefore, efforts should be made to avoid a delay in the diagnosis of ocular TB and to identify prognostic factors for visual outcomes and complications.