Biomedical subjects
Publications and source records attributed to K H Wassill.
A video technique is described to record ocular motions and positions of both eyes simultaneously in all degrees of freedom. This non-invasive method allows a 3-D positional analysis with free gaze directions and head tilts for measuring all ocular degrees of freedom, including torsion.
BACKGROUND: It has long been a goal to develop a means to measure squint angles in three dimensions simultaneously. A three-dimensional binocular method is naturally needed especially with surgical procedures that affect three dimensions of ocular motility. METHODS: Special modifications of a videographic method provide simultaneous online data on the three-dimensional position of the eyes. The interocular difference is equal to the amount of squint, depending on the direction of gaze, head-tilt/direction of gravity, and convergence. RESULTS: The method introduced provides three-dimensional and binocular documentation of ocular movements. This could lead to improved pre- and postsurgical examination, especially of rotational disturbances, and it could also offer an objective means for comparing the results of various surgical procedures.
BACKGROUND: In this investigation the clinical usefulness of an automatic handkeratometer was compared to well-known methods of corneal power measurement. Moreover, we examined the influence of the patient's position on the results. PATIENTS AND METHODS: One investigator measured 31 eyes of children in the age of 4-11 years (mean 6.3 y.) and 60 eyes of adults in the age of 22-71 years (mean: 48.3 y.) without corneal disorders consecutively by handkeratometer standing and lying, by autokeratometer and computerized videokeratography. Steepest (r1) and flattest (r2) radius, cylinder power and corresponding axis were subjected to statistical analysis. RESULTS: The mean values of the corneal radii (r1/r2) of the children were 7.63/7.82 mm for handkeratometer standing, 7.63/7.84 mm for handkeratometer lying, 7.62/7.84 mm for autokeratometer and 7.70/7.87 mm for videokeratoscope. The cylinder power was 1.11 dpt for handkeratometer standing, 1.09 dpt for handkeratometer lying, 1.23 dpt for autokeratometer and 0.95 dpt for videokeratoscope. Analysis of intraindividual variability produced by the instruments concerning astigmatism (dpt) showed in substraction for comparison of handkeratometer standing with handkeratometer lying 0.02 +/- 0.29 SD, of handkeratometer standing with autokeratometer -0.12 +/- 0.37 and of handkeratometer standing with videokeratoscope 0.16 +/- 0.35. A further comparison concerning cylinder (dpt) of handkeratometer lying with autokeratometer was -0.13 +/- 0.42 and handkeratometer lying with videokeratoscope 0.14 +/- 0.43. Difference comparison of astigmatism measurements in the 95% confidence interval (aspired difference of zero) demonstrated a high statistically significant relationship of handkeratometer standing (p < or = 0.0001) and handkeratometer lying (p < or = 0.0002) with the videokeratoscope. Mean values of the adult eyes (r1/r2) valued 7.56/7.76 mm in handkeratometer standing, 7.56/7.76 mm in handkeratometer lying, 7.57/7.78 mm in autokeratometer and 7.6/7.76 mm in videokeratoscope. The mean cylinder power with the corresponding axis was 1.15 dpt/80.5 degrees in handkeratometer standing, 1.15 dpt/77.8 degrees in handkeratometer lying, 1.15 dpt/78.3 degrees in autokeratometer and 0.95 dpt/75.2 degrees in videokeratoscope. CONCLUSIONS: The results and standard deviations of corneal power measurements of the handkeratometer were independent on patient's position and very similar to those of a common autokeratometer and videokeratoscope. Because of its quick and simple operation the handkeratometer was well accepted for corneal examination of children and can therefore be a useful alternative.
INTRODUCTION: MELAS is most often due to an mentally transmitted A-G transition mutation of mitochondrial DNA (mtDNA) at position 3243. In this study we report on the clinical spectrum associated with the mutation in the largest family reported so far. PATIENTS AND METHODS: In a family with three MELAS cases we identified 47 persons at risk for the mutation; sufficient data was available on 29. Mitochondrial disease was diagnosed in two of 9 deceased numbers (posthumous molecular analysis in one); 27 surviving family members underwent examination and 25 a molecular analysis of mt DNA from lymphoblasts. Then had a muscle biopsy and two were later autopsied. RESULTS: All 26 cases investigated by molecular analysis showed the mutation at position 3243. The 18 symptomatic patients without stroke-like episodes had sensorineural hearing loss in 15 cases, diabetes in 6, nephropathy in 7, mild myopathy in 4, cardiomyopathy in 2, cerebellar disease in 4 and mental retardation in 2 cases. Eight carriers were asymptomatic. Autopsy showed > 80% mutant mt DNA in all tissues except blood (20%) examined in a MELAS patients, but < 20 mutant mt DNA in all tissues except lever (40%) and kidney (70%) in a patient with hepatopathy, renal failure and diabetes. Histologic and biochemical studies of muscle biopsy were often non-informative. CONCLUSIONS: The mutation of mt DNA at position 3243 causes a multisystem disorder with a variable phenotype due to heteroplasmy. Most carriers are oligosymptomatic with hearing loss and a variety of neurological and internal medical symptoms. Diabetes, cardiomyopathy and renal disease, which is newly reported here for this mutation, are frequent. The blood test is a reliable screening tool in affected families, but is of prognostic value only combined with examination of other tissues.
UNLABELLED: The objective photographic documentation and follow-up examination of changes in the eye's anterior segment is gaining importance as part of the daily practice. Until now, however, it has been linked with specially designed and expensive photographic equipment. A large number of ophthalmic units around the world do not have access to any form of photography. The advances in videographics do not offer an adequate alternative concerning both fineness of the grain and price per picture. MATERIAL AND METHODS: After installation of a new slit-lamp camera adapter, it was possible to produce color prints and slides. A 35-mm SLR camera with a spot-metering system, a clear view-finder focusing screen, highly sensitive slide film (ISO 640/29 degrees) and a standard 50 mm lens was used. No additional light sources or flashes were necessary in this camera-slit-lamp combination. CONCLUSION: This system is suitable to take color photographs of good quality and makes ophthalmic photography readily available, particularly in circumstances where more sophisticated photographic equipment is not available. Because of the fast and easy installation and the additional use for gonioscopic or fundus photography this combination is profitable even for inexperienced photographers.