Suppression of Covid-19 outbreak among healthcare workers at the Treviso Regional Hospital, Italy and lessons for ophthalmologists.

PURPOSE: To describe a strategy to reduce Covid-19 spread among healthcare workers and provide ophthalmologists with recommendations useful for a possible second wave of Covid-19 in Autumn. METHODS: Epidemiological surveillance at the Cà Foncello Hospital (Veneto, Italy) since 24 February 2020 to 24 April 2020 when the municipality of Treviso was hit by the Covid-19 outbreak. The number of naso-pharigeal (NP) swabs performed was 7010. RESULTS: The number of infected among healthcare workers was 209/ 3924 (5.32%): medical doctors: 28 cases / 498 (5.6%). None among ophthalmologists; specialized nurses: 86/1294 (6.4%) None in the ophthalmic unit; intermediate care technicians: 68/463 (14.7%). The 46% of the positive tested were asymptomatic. We share key suggested actions for the reorganization in ophthalmological services: be part of a global epidemiological local strategy of containment (Testing, Tracing, Treating); protect your department: Keep on screening patients by telephone interview before entering the hospital; promote continuous and appropriate use of PPE both for doctors and for patients; make any effort to obtain a continuous flow of patients in every line of the ophthalmic service; treat appropriately any single patient with vision threatening condition; avoid unnecessary or futile testings and examinations. CONCLUSION: The Treviso model shows that it is possible and safe to keep on performing high risk hospital activities like ophthalmology, even in the epicenter of covid outbreak, if adequate actions are performed. We discuss about the value of NP swabs and serological tests as a strategy in case of a second wave of infections.

'Gamma' band oscillatory response to chromatic stimuli in volunteers and patients with idiopathic Parkinson's disease.

The signal structure of the responses to equiluminant chromatic and achromatic (contrast) stimuli was studied in normal volunteers and patients with mild to moderate idiopathic Parkinson's disease. Visual stimuli were full-field (14 x 16 deg) achromatic or equiluminant (red-green or blue-yellow) sinusoidal gratings at 2c/deg and 90% contrast presented in onset-offset mode. The signal was processed offline by DFT and factor analysis was performed in the frequency domain. The conventional VEPs to chromatic onset stimuli showed a monophasic negative wave, while the response to offset stimuli was comparable in shape to the on-/offset achromatic responses; latencies were longer and amplitudes higher than those of responses to contrast stimulation. In patients, latencies were longer than in controls after achromatic and (to a lesser extent) red-green stimulations, but not after blue-yellow stimulation; amplitudes were comparable in all stimulus conditions. In healthy subjects, two non-overlapping factors accounted for the approximately 2-30.0 Hz and approximately 25.0-50.0 Hz signal components (representative of the low-frequency VEP and gamma oscillatory responses, respectively); the frequency of the approximately 25.0-50.0 Hz factor was lower after color than after contrast stimulation. The same factor structure was identified in patients, but the peak frequency of the factor on gamma activity was higher than in controls and did not vary with color-opponent stimulation. These observations indicate that stimulus-related gamma activity originates in cortex irrespective of the activated (magno-, parvo-, or konio-cellular) visual pathway, consistent with the suggested role in the phase coding of neuronal activities. Some dopaminergic modulation of gamma activity is conceivable.

Abnormal waveform of the human pattern VEP: contribution from gamma oscillatory components.

PURPOSE: Stimulus-related oscillatory activity above approximately 20 Hz (gamma band) is observed in the firing rate and membrane or field potentials of neurons in the visual cortex of cat and monkey. Cortical mass responses in the same frequency range are evoked in humans by contrast stimulation and proved (partly) independent of conventional VEPs. Visual evoked responses (pattern VEPs) with abnormal waveform (quasi-sinusoidal or with bifid wave P100) are reportedly common in diseases affecting the visual pathways (e.g., multiple sclerosis). Contributions of gamma activity to the distorted VEP waveform are possible if the mechanisms of generation are differentially affected by brain disorders. This hypothesis was investigated in patients with documented impairment of the visual system. METHODS: VEPs and oscillatory responses to contrast stimulation (central 9 degrees of visual field; 1.3 to 5.0 cyc/deg; 80% contrast; reversal at 2.13 Hz) were recorded in 765 patients referred for standard visual testing and frequency analyzed. Controls were 40 healthy volunteers. The stimulus conditions and recording procedures replicated previous normative studies on the human oscillatory response. RESULTS: Conventional VEPs were replaced by oscillatory responses comparable to those of controls in the unfiltered recordings of 9.8% of examined patients (with postchiasmatic disorders in 59.9% of cases). Signal amplitude in the frequency interval of the VEPs (below approximately 19 Hz) was significantly lower in the frequency spectra of patients than of controls but did not differ in the frequency range above 20 Hz, reflecting the oscillatory response. CONCLUSIONS: The human gamma oscillatory response mediating in cortical visual information processing further proved independent of the VEPs. It can contribute to VEP waveform distortion, and its observation in substitution of VEPs should be regarded as an indication of impaired visual pathway function.

Effect of topical 0.1% indomethacin solution versus 0.1% fluorometholon acetate on ocular surface and pain control following laser subepithelial keratomileusis (LASEK).

PURPOSE: To compare the effect of topical 0.1% indomethacin solution versus 0.1% fluorometholon acetate in the early postoperative period after LASEK treatment. METHODS: One hundred thirty-five patients undergoing LASEK, having been randomized in a double-masked manner into 2 groups (1 receiving indomethacin and 1 fluorometholon), were evaluated 2-4 days before and 4 days after treatment. We examined corneal fluorescein staining and corneal esthesiometry; the level of pain experienced was reported by the patient on a visual pain scale. In addition, haze was evaluated at 14 +/- 1 weeks after surgery. RESULTS: The pain level and corneal fluorescein staining were significantly less in the indomethacin group. Corneal esthesiometry was reduced to the same extent in the 2 groups. There were no statistically significant differences in haze presentation between the 2 groups. CONCLUSION: Our study highlights the efficacy of indomethacin solution compared with fluorometholon as a pain reducer after LASEK treatment and suggests that indomethacin is associated with a faster epithelial healing process.