New stand magnifiers do not meet rated levels of performance

A new range of stand magnifiers has been released by the COIL company in the United Kingdom. Examination of these magnifiers reveals that they fail to deliver the rated magnifications labelled prominently on the appliances, as a result of the manufacturer's conformance with the requirements of the German DIN standard and the use of back vertex power (F'_v) rather than equivalent dioptric power (F_m) of the magnifier. In this study we provide information on the optometric parameters of these new stand magnifiers that will assist the more accurate specification of improvements in vision expected from their use.     

Prevalence of the Neonatal Autopsy: A Report of the Study Group for Complications of Perinatal Care

Neonatal autopsy findings are valuable additions to the information base for current cases and future perinatal care, so the reported decline in the autopsy rate is disturbing. In order to estimate the prevalence of the neonatal autopsy among a large population of deaths, we surveyed participating institutions of the Study Group for Complications of Perinatal Care. Investigators from 37 neonatal intensive care units, located in 9 children's hospitals, 4 hospitals for women and infants, and 24 full-service pediatric and adult care hospitals, reported their neonatal death and autopsy rates for 1989. The overall neonatal autopsy rate was 51% among 1645 neonatal deaths. The rate was variable, ranging from 22 to 100%. We found the neonatal autopsy rate to be lower than previously reported and not apparently influenced by the type of center or by the type of medical staff at the centers. In order to assess and potentially reverse the current low rate, the influence of neonatal demographic and clinical factors, as well as physician-related factors, must be studied.     

Bilateral Hematogenous Pseudomonas aeruginosa Endophthalmitis After Lung Transplantation

Pseudomonas aeruginosa commonly colonizes the airways of patients with cystic fibrosis (CF). However, the occurrence of bacteremia with metastatic infection to the eye causing endogenous endophthalmitis is very rare. In the setting of lung transplantation, the significance of P. aeruginosa bacteremia in patients with CF whose airways are colonized before transplantation is unknown. We report a case of bilateral P. aeruginosa endogenous endophthalmitis in a patient with CF after lung transplant without documented bacteremia. The patient presented with acute eye symptoms in the presence of a left atrial thrombus and the disease followed a rapidly progressive course requiring aggressive medical-surgical treatment. Typically P. aeruginosa endophthalmitis has been associated with a poor visual prognosis. However, with combined medical-surgical management this patient retained useful vision in one eye without having retinal detachment or requiring enucleation. Endogenous endophthalmitis should be considered in the differential diagnosis of ocular complaints in patients with CF after lung transplant.     

Phenylephrine-induced anterior chamber hypoxia

The effect of topical phenylephrine 10% solution on anterior chamber oxygen tension (PO2) was studied in cats using an oxygen-sensitive electrode inserted into the midanterior chamber. A decrease in anterior chamber PO2 was usually observed within eight to 25 minutes and declined steadily thereafter. Within two hours, the drug caused a dramatic 60% reduction in anterior chamber oxygen tension (P less than or equal to .0005). We suggest that the mechanism for this phenylephrine-induced anterior chamber hypoxia is reduced blood flow, mediated by the direct vasoconstrictive effect of the drug and compression of the iris vasculature (induced by dilatation). The resulting decrease in the caliber of the iris arteries produced a parallel decrease in blood volume and flow which resulted in diminished PO2. Phenylephrine 10% may contribute to hypoxia and exacerbate the underlying pathology in those disorders where hypoxia plays an important causal role.     

Comparison of photocoagulation with the argon, krypton, and diode laser indirect ophthalmoscopes in rabbit eyes.

PURPOSE: The purpose of this study is to compare photocoagulation with the argon green, krypton red, and diode infrared laser indirect ophthalmoscopes in an experimental setting. METHODS: Photocoagulation was performed with each of the laser indirect ophthalmoscopes in a grid pattern within one sector of the same eye of 14 Dutch-belted rabbits. Treatment was performed either with or without scleral depression. Measurements of the retinal burn diameters were performed after hemisecting the globes, and the burns were examined with light microscopy. RESULTS: Variation in burn intensity and diameter (10% to 28%) was common with all 3 laser indirect ophthalmoscopes. Five times more output energy was required to make equivalent burns with the diode laser indirect ophthalmoscope than with the argon or krypton laser indirect ophthalmoscopes. Choriovitreal hemorrhages only occurred during scleral depression. Histopathologically, the argon green laser indirect ophthalmoscope burns spared the choroid and inner sclera, while the intense krypton and diode burns had full-thickness choroidal involvement and even thermal injury to the inner sclera. Scleral depression reduced the mean energy required to create equivalent burns with all three laser indirect ophthalmoscopes. There was a 10% to 40% reduction in the mean retinal burn diameter with scleral depression (argon green, P < 0.0005; krypton red, P < 0.0005; and diode, P < 0.025). CONCLUSION: Photocoagulation with the argon green, krypton red, or diode infrared laser indirect ophthalmoscopes is a safe and effective method of retinal ablation. Decreasing the posterior nodal distance of the eye with scleral depression will produce a smaller spot on the retina with the laser indirect ophthalmoscope.     

Pheochromocytoma and paraganglioma: comparison of MR imaging with CT and I-131 MIBG scintigraphy

To ascertain the magnetic resonance (MR) imaging characteristics of pheochromocytomas and paragangliomas and to compare MR with computed tomography (CT) and iodine-131 metaiodobenzylguanidine (I-131 MIBG), 19 patients (18 with pheochromocytomas, one with a paraganglioma) were studied. The 18 patients with pheochromocytomas had had positive findings with I-131 MIBG scintigraphy. Abdominal pheochromocytomas were generally hypointense compared with normal liver on T1-weighted MR images and extremely hyperintense on T2-weighted MR images. MR imaging was preferable to CT in the evaluation of primary pheochromocytomas due to superior tissue characterization, particularly in the patient with hypertension and borderline catecholamine levels. For patients with recurrent or metastatic disease, the data suggest that I-131 MIBG scintigraphy is the examination of choice.