Outcome of complete intrastromal ring implantation using femtosecond laser in pellucid marginal degeneration.

PURPOSE: To evaluate the effect of complete intrastromal corneal ring implantations on patients with pellucid marginal degeneration (PMD). DESIGN: Prospective interventional case series. PATIENTS AND METHODS: Thirty-three eyes with PMD were included into the study. After pocket creation with femtosecond laser (Femtec; 20/10 PerfectVision), MyoRing implantation was performed. Uncorrected and corrected distance visual acuity (UDVA, CDVA), subjective refraction, keratometry, central corneal thickness, corneal biomechanical profile (Ocular Response Analysis), and whole-eye wavefront aberrometry (iTrace) were evaluated preoperatively and also postoperatively, 1 month, 3 months, 6 months, and 1 year after the operation. RESULTS: One month after surgery, significant improvements were observed in UDVA (ANOVA; P=0.02), mean keratometry, sphere (ANOVA; P <0.001), and cylinder (ANOVA; P=0.04) with no significant changes afterwards. No significant change occurred in the corneal biomechanical profile. Primary coma and trefoil reduced after 1 year (ANOVA; P values were 0.02 and 0.06, respectively). Primary spherical aberration significantly increased according to the 1-year follow-up (ANOVA; P<0.001). No significant complication was observed. CONCLUSION: MyoRing is considered as a treatment modality for spherocylindrical correction in patients with PMD, with an acceptable safety and efficacy profile.

A practical review of methods for measuring the dynamic characteristics of industrial pressure transmitters.

Three methods exist for testing the response times of pressure transmitters in situ: the power interrupt test, the noise analysis technique, and the pink noise technique. The noise (or random signal) analysis technique is a passive in situ technique that does not interfere with plant operation, uses already existing plant sensors and instrumentation, accounts for the effects of process conditions on plant equipment performance, and includes any response-time delays caused by transmitter sensing lines. The power interrupt test is a simpler and less-time-consuming test than noise analysis for measuring the response time of force-balance pressure transmitters. The pink noise test is useful for pressure transmitters where process fluctuations do not normally exist or they are inadequate for using the noise analysis technique to test response time.

Pressure transmitter accuracy.

This paper discusses the key causes of calibration drift in pressure transmitters and procedures for calibrating pressure transmitters to ensure their accuracy. Calibrating pressure transmitters involves adjusting the potentiometers in the sensor that controls the zero (lowest pressure at which a transmitter is calibrated) and span (the range of pressure the transmitter is to indicate) of the transmitter. The initial or bench calibration of pressure transmitters involves using a constant pressure source such as a deadweight tester. Once the transmitters are installed, temperature, pressure, humidity, vibration, maintenance activities, and normal aging can degrade their accuracy. Transmitter accuracy can also be degraded by transmitter sensing lines, when the water in a sensing line reference leg boils off, when non-condensable gases in the reference leg dissolve, and when voids, blockages, freezing, or leakage occur in sensing lines. On-line calibration techniques enable plants to avoid these accuracy problems by monitoring the output of an individual transmitter.

Febrile seizures: clinical course and diagnostic evaluation.

A study was done on 111 children admitted in a university hospital in Tehran with fever and seizures to document the pattern of illness and to define indications for performing a lumbar puncture in children with fever and convulsions. Bacterial meningitis was diagnosed in 4 patients, aseptic meningitis in 2 and 105 children had febrile seizures. The cause of fever was gastro-enteritis in 39 patients and upper respiratory tract infection with or without Otitis media in 40. Although most patients were drowsy on admission (n = 93), none had any signs of meningeal irritation, except one child with slight nuchal rigidity. Out of the 4 children with bacterial meningitis, 3 had meningeal signs, but in one 10 month old baby with no signs, the diagnosis was made on the cerebro-spinal fluid findings after a lumbar puncture. These results support the view that a lumbar puncture should be performed on all infants under 12 months who present with fever and convulsions and strongly considered between 12 and 18 months. After 18 months a lumbar puncture is mandatory in the presence of signs of meningeal irritation.

Carcinoma of the thyroid gland in Iran.

Of the 1698 cases of thyroid disease seen during the 17 years 1956-72 in the Taj Cancer Institute, Tehran, 398 were cases of carcinoma, an incidence of 23.4 per cent. The factors involved in this high incidence of malignancy are discussed and the treatment of these patients is described.

Ewing's tumor. Review of 73 cases.

Observations on 73 cases of Ewing's tumor confirmed that this neoplasm occurs in twice as many males as females, mostly between the ages of 11 and 20. In contrast with other reported series, 61.6% of lesions in our patients were in the flat bones. Definite diagnosis cannot be based solely on clinical and radiological changes, and no patient suspected of suffering from Ewing's tumor should receive x-ray treatment or any other kind of therapy unless the diagnosis has been proved histologically, by means of open biopsy. Supervoltage radiation therapy combined with chemotherapy produces better results than other kinds of treatment.