Influence of Short-Term Orthokeratology to Corneal Tangent Modulus: A Randomized Study.

PURPOSE: Influence of orthokeratology on corneal biomechanics is equivocal using Ocular Response Analyzer, ORA. Implementing indentation method, corneal tangent modulus was measured and monitored in short-term orthokeratology. MATERIALS AND METHODS: Sixteen young subjects with refractive errors between -4D to -5D sphere and astigmatism within -1.50D were recruited. One randomly selected eye wore orthokeratology lens (treatment), and the fellow eye wore conventional rigid gas permeable lens (control). Lenses were worn for 30 and 60 minutes and one night separately with a week of washout period in between. The first two visits were randomly scheduled and before the overnight visit. Eyes were kept closed during all the lens wearing periods. Corneal radius, thickness, and biomechanics (using both ORA and an indentation device) were compared between eyes prior to each visit, and then before and after lens wear. Associations between baseline corneal biomechanics and central cornea from overnight visit were investigated. RESULTS: Corneal parameters were similar in each visit before lens wear. Significant corneal flattening was observed in treatment eyes, and flattening increased with wearing time. Control eyes showed no significant corneal curvature changes. Corneal resistance factor (CRF) reduced by 0.42mmHg (± 0.68mmHg) after 30 minutes of orthokeratology treatment. Corneal hysteresis (CH) reduced by 0.42mmHg (+/- 0.63mmHg) in control eyes from overnight wear. Both eyes showed stable tangent modulus, E, throughout the study. A lower CH (r = 0.51, p = 0.046) and a higher E (r = 0.53, p = 0.037) at baseline was significantly associated with greater corneal flattening along the flattest meridian in treatment eyes. CONCLUSIONS: Short-term orthokeratology had no significant effect on corneal tangent modulus. Changes in CH and CRF could be related to their intrinsic measurement variability. Corneal tangent modulus provided another measure of corneal biomechanics. Long-term study is required to investigate predictive role of corneal biomechanics in orthokeratology.

Outcome of Encephalitis in Pediatric Intensive Care Unit.

OBJECTIVE: To review pathogens, morbidity and mortality in pediatric intensive care unit (PICU) patients with viral and infectious encephalitis. METHODS: Retrospective chart review of all patients with encephalitis admitted to the PICU between 2002 and 2014 was done. RESULTS: Encephalitis (n = 46) accounted for 2.7 % of PICU admissions, but 11.8 % PICU mortality over a 12-y period. A microorganism (primarily virus) was identified in 59 % of encephalitis patients in the PICU. Enteroviruses and herpes viruses were isolated from the cerebrospinal fluid (CSF). Respiratory viruses [such as respiratory syncytial virus (RSV) and influenza viruses] and enteric viruses (such as rotavirus and norovirus) were obtained in the nasopharyngeal aspirate and stool respectively, but undetectable from the CSF. More than one-fourth patients with encephalitis died in the PICU. Boys accounted for 85 % of nonsurvivors and 52 % survivors (p = 0.038). Mechanical ventilation, inotrope, intravenous immunoglobulin (IVIG) and corticosteroid usage were significantly higher among non-survivors (p 0.001-0.044). Binomial logistic regression showed that patients who received corticosteroid had a lower chance of survival than those who did not after adjusting for gender, IVIG and mechanical ventilation (adjusted odd ratio = 0.071, 95 % CI 0.006-0.881; p 0.039). Eighteen (55 %) of the survivors had moderate-to-severe neurodevelopmental impairments. CONCLUSIONS: Encephalitis is associated with significant mortality despite intensive care. Over 25 % case died and 55 % of survivors had moderate-to-severe neurodevelopmental impairments. There appeared to be no emerging outbreaks of encephalitis during the 15-y study period.