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A 17-year-old black male first complained of a relatively acute visual loss in both eyes just weeks before his 15th birthday. Extensive evaluations provided no definite organic cause for the acuity drop from 20/25 in June 1983 to 20/200 in November 1983. A psychogenic etiology was suspected but never confirmed. To date, optical devices provide the only means in attaining maximum visual efficiency.
The assessment of visual fatigue developing in the process of performing precision works with the usage of monocular optic devices has shown that visual fatigue develops due to impairment of the functional state of binocular functions to which changes of the accommodation system join. The obtained psychophysiologic portraits can be helpful for a quantitative assessment of developing visual fatigue.
It is shown that refolding of horse cytochrome c at pH 2.0 induced by an increase of ionic strength occurs in three kinetic phases with the rate constants similar to those observed for the refolding of this protein into the native state. The rate constants and amplitudes of these phases do not depend on the final ionic strength and phase amplitudes are not temperature-dependent. Reasons for the complex kinetics of the cytochrome c refolding at acid pH are discussed. A description of a "stopped-flow" attachment compatible with different commercial optical devices is provided.
The measurement of capillary permeability in chronic venous insufficiency (CVI) requires techniques able to modify local microcirculatory hemodynamics and therefore the results. As for instance, venous occlusion in the Landis test or occlusive plethysmography. We are presenting a selective method which visualizes and quantifies capillary permeability without modifying the hemodynamics. A skin area on the lower extremity is observed on a microscope with blue filters. This optical device is linked with a camera transmitting information to a TV monitor and a video cassette recording system. When focusing is done, the patient's brachial vein is injected with an IV bolus of 1 ml if sodium fluorescein (Na flu). This dye diffuses rapidly from the intra toward the extra-capillary compartment. A densitometer connected to a graph measures the capillary permeability selected dynamics. The capillary permeability to Na flu is evaluated qualitatively on the TV screen (pericapillary halo), and quantitatively by the densitometric curve. In practice, this technique is advocated in the physiopathological study of any edema, especially in early CVI.
Vergence-induced accommodation (V-A) and accommodation-induced vergence (A-V) were measured in human subjects before and after they had worn various optical devices for 30 min. Laterally displacing periscopic spectacles, which increase the required change in vergence per unit change in accommodation, caused decreases and increases in the gain of V-A and A-V responses, respectively. These observations are consistent with the view that the gain of the neural cross-linkages between vergence and accommodation are subject to adaptive regulation. However, there were strong asymmetries: Medially displacing periscopes (cyclopean spectacles), which reduce the required change in vergence per unit change in accommodation to zero, were almost totally without effect. Base-out prisms, which increase the required convergence by an amount that is constant for all viewing distances, caused downward and upward shifts in the V-A and A-V response curves, respectively. Base-in prisms, which reduce the required convergence by a constant amount for all viewing distances, caused downward shifts of A-V curves but had no significant effect on V-A curves. These effects of prisms are in essential agreement with the work of others and confirm the existence of adaptive elements that regulate the bias in the vergence and/or accommodation control systems. Secondary effects of wearing periscopes and prisms indicated a certain lack of specificity in the sensing of gain and bias errors: vertical shifts of V-A and A-V curves (resembling those seen with base-out prisms) often occurred with the laterally displacing periscopes, and gain changes (generally resembling those seen with laterally displacing periscopes) often occurred with the base-out prisms.
Heparinized survey samples from the College of American Pathologists from 1981 through 1984 were reviewed to assess effects of the various reagents and instrumentation on the performance of the activated partial thromboplastin time (aPTT) in response to heparin. Responsiveness of the aPTT to the concentration of heparin as well as its sensitivity to the detection of heparin in the therapeutic range was most affected by choice of reagents. Precision was most affected by choice of instruments with photo-optical devices being roughly comparable. A previously described effect of calcium vs sodium salts of heparin was not supported by these data. Survey results were compared with results from fresh plasma samples from patients who had received heparin therapeutically and with response curves obtained from specimens heparinized ex vivo. The pattern of reagent dose responsiveness to the heparinized patient samples differed from that seen with survey samples and with the ex vivo heparinized fresh plasma samples. In addition, intrinsic characteristics of the individual specimens exerted substantial effects on the test results for all specimen types. Therefore, one cannot automatically assume that phenomena that hold for one form of plasma preparation are applicable to another. The nature and source of the heparinized plasma specimen must be taken into account when interpreting aPTT results.
Various gonioscopic lenses were tested in the operating room for viewing the size and foot placement of the Choyce Mark VIII intraocular lens. The Tennant and the Worst fiber optic devices were fairly adequate. The Thorpe surgical gonioscope was the easiest to handle, and provided a good view with the operating microscope.
Foetoscopy consists of the introduction into the ovular cavity, at the beginning of the second trimester of pregnancy, of an optical device in order to be able to observe the foetus and the foetal surface of the placenta. It may be used to detect certain foetal malformations which are not seen by echography and to collect foetal red cells by direct puncture of a placental vein. Its major indication is the prenatal diagnosis of homozygous forms of haemoglobinopathies: sickle cell disease and beta-thalassaemia. It is a dangerous investigation which requires great experience and perfect organisation.
Eighteen eyes were preoperatively evaluated and operated on by the method of Fyodorov. Although Fyodorov stated that his formula improves the predictability of radial keratotomy, we know of no previously published studies that included it. They all omitted the Maklakov measurement of scleral rigidity, although Fyodorov stated that it may influence the surgical result profoundly. Maklakov measurement of scleral rigidity does not correlate with Schiotz measurement of scleral rigidity. The overall predictability of the formula at six to 14 months postoperatively was good except in the eyes of a diabetic patient. The formula enables the surgeon to show the patient preoperatively what his likely result will be. Sixteen of 17 eyes (94%) in the refraction range of -2.00 to -7.50 had a visual acuity of 20/50 or better. The patient satisfaction rate was excellent. There were no important complications. Subjective glare and glare independently measured with the Miller-Nadler glare tester was absent in all tested eyes except one eye when it was dilated. Radial keratotomy as described here is safe, effective, and reasonably predictable and may be offered to selected patients who have personal requirements that are not fulfilled by standard optical devices.
The attempts for closing tympanic perforations has been a matter of concern between the otologists since past times. BANZER, in 1640, tried to seal them with pork bladder; YEARSLEY, in 1850, was the first to use a fragment of cotton wool to patch them up; BERTHOLD, in 1878, used skin grafts; and BLAKE, in 1887, did the same with papier patches. From 1950 onwards, owing to the spreading of optical devices, the utilization of several materials become generalized. Although independently of the followed technique high rates of closures were recorded, it seems advisable to stablish a procedure joining good results and the easiness of placement of the piece and, specially, to avoid the general anesthesia. In our Department the butterfly-like method of myringoplasties is practised in certain cases. The procedure is based in that of STROUD. The results are not better as those gained through classics but it is worth because of the advantages of application and the accuracy of placement.
Tubal factors cause infertility in about a third of cases. With current diagnostic techniques, such as laparoscopy and hysterosalpingography, only a fraction of the causes of tubal infertility can be diagnosed and in many cases misdiagnosis results. Newer methods, such as ampullosalpingoscopy enable examination of the fimbria and ampullar segment of the fallopian tube, but the examination of the proximal tube, in which 10-20% of occlusions occur, is still impossible. We describe a new diagnostic technique, falloposcopy. It involves the transuterine insertion of a fiber optic device into the fallopian tube through a hysteroscope. This technique enables direct visualization of all segments of the fallopian tube, as well as removal of intratubal debris or adhesions. Using falloposcopy, a new grading method for tubal disease has been developed. We describe the results of 129 falloposcopic procedures in 82 women. Following falloposcopy, women with mild to moderate disease, according to the new classification, have conceived without further therapy during a follow-up period of up to 3 years. Falloposcopy may aid in differentiating between patients suitable for tubal surgery and those who should be referred for in vitro fertilization.
PURPOSE: To study the flow velocity of erythrocytes and leukocytes in the same retinal capillaries in cat eyes. METHODS: Blood cells from cats were stained with fluorescent label and reinjected into the animals. An electro-optical device combined with a highly sensitive CCD camera detected the fluorescent signal from the labeled blood cells. The signal was stored on a videotape (VHS-PAL, 25 frames per second) and later analyzed digitally. Twenty leukocytes were identified, each flowing through a separate retinal capillary pathway. The capillary pathways were categorized as simple and complex according to their morphologic complexity. Observations were made on 10 simple and 10 complex capillary pathways. The passages of one leukocyte and 20 erythrocytes in each capillary path were recorded and analyzed. The blood cell velocity ratio was calculated from the number of frames needed for each cell to complete a passage through the capillary pathway (higher velocity = fewer frames). RESULTS: The erythrocytes traveled faster than the leukocytes in both the short and long capillary pathways. The frames ratio (mean percent +/- standard deviation) of erythrocyte-leukocyte passage in the same capillary pathway was 84.55% +/- 2.0% in the short ones and 66.21% +/- 7.1% in the complex ones. The main deceleration in leukocytes flow was noted in the looping parts of the complex capillary pathways. CONCLUSIONS: The velocity of leukocytes is slower than that of erythrocytes in a given retinal capillary pathway. The structural complexity of a capillary pathway has a greater effect on leukocytic velocity than on erythrocytic velocity.
In recent years, there has been increasing interest in refractive surgery among patients and physicians. Refractive surgery lessens or eliminates the need for contact lenses or glasses. The goal of refractive surgery is to allow an individual more independence from optical devices. Technologic innovations have improved the predictability and safety of surgical correction of refractive errors and actually revolutionized treatment.
BACKGROUND: A 5-year-old Hispanic male with an ocular history of retinopathy of prematurity was seen for an evaluation of his functional abilities and a determination of the possible treatment options for rehabilitation. The greatest concern was to provide the boy with the tools necessary to ensure success in the educational system. METHODS: A low-vision evaluation was performed and baseline information was obtained, including distance visual acuities, near visual acuities, visual fields and refractive error. This data was then used to determine if, in a classroom setting, the child would encounter any difficulties that could benefit from assistive optical devices or modifications of environment. RESULTS: The child demonstrated a large angle of head turn in order to eccentrically view to obtain his best visual acuity. His refractive error had no effect on this visual acuity at distance. Visual acuities taken at near demonstrated a working distance of 4 cm with preference to using the right eye. A gross confrontation field suggested a relatively full field in the right eye, but a temporal field loss in the left eye. CONCLUSIONS: A monocular bifocal system was prescribed for use in the classroom and at home when studying. The bifocal segment was a round +24 diopter aspheric lens, 22 mm in diameter, which was reshaped into a flat-top and adhered to a carrier lens. The carrier lens was ordered with 10 prism diopters base left in each eye. This system addressed both the large eccentric viewing position and the magnification necessary to alleviate the accommodative system.
BACKGROUND: Reports in the literature concerning the evaluation and low vision management of visually impaired children are limited, resulting in a lack of information about the characteristics and needs of this population. METHODS: A review was performed of 762 children evaluated over a 14-year period in a low vision clinic program coordinated by the Iowa Braille and Sight Saving School. RESULTS: The age, sex, ocular condition, best corrected visual acuity, habitual near point working distance, and optical devices recommended for use by these children were analyzed. CONCLUSIONS: Ongoing, comprehensive multidisciplinary low vision services are necessary to help children with visual impairments meet their educational, vocational and avocational needs. With ongoing low vision care unnecessary costs-such as those for large print material-can be avoided, therefore creating a significant savings to local or state educational services.
There are many children who have subnormal vision in spite of successful cataract surgery and aphakic spectacle lenses. There are children who have lens opacities for whom the state of aphakia would not be an improvement. Careful evaluation of functional vision, careful refraction, and the prescription of high adds or other optical devices are part of complete ophthalmological care for every one of these children. The dioptric strength of the reading add is determined by the functional reading vision and the calculation of the reciprocal of the visual acuity. It is also important to realize that many children who have lens opacities do not require special aids; functional vision is adequate until their accommodative reserve wanes with age. Continuous-wear contact lenses may eventually replace spectacle corrections for the aphakic child.
PURPOSE: In order to associate the major benefits of the coronary artery bypass graft (CABG) with a less aggressive procedure minimally invasive coronary artery bypass graft (MICABG) has been utilized. The aim of the work is to report our initial experience with this technical approach, using video assisted thoracic surgery (VATS) to facilitate the operation. METHODS: Twenty-six patients, 19 males with ages from 44 to 83 years old, and having isolated lesion of the anterior descending artery were operated upon. Left anterior minithoracotomy of 8-10 cm was performed at the fourth intercostal space. Through this incision the optical device for VATS as well as the surgical instruments were placed in order to provide the complete left internal mammary artery (LIMA) dissection. Bypass circulation was not used and cardiac rate was decreased with the use of intravenous betablockers. For LIMA--anterior descending artery anastomosis, proximal and distal tourniquets were used and 1.5 mg/kg of heparin was intravenously administered. RESULTS: All patients presented satisfactory postoperative evolution, being discharged from the hospital at 72 h after surgery in the majority of the cases. There were delay in two patients healing of incisions and 25 patients have remained asymptomatic, with a mean in postoperative follow-up of four months. One patient died in the second postoperative month due to stroke. CONCLUSION: MICABG makes the surgery possible with better esthetic effect, lower cost and enables faster recovery than the conventional one. The use of VATS through the thoracotomy itself, allows the LIMA dissection without other incisions. It also permitted more ample dissection of the LIMA when compared to minithoracotomy without VATS.
After having monitored haemodynamics during haemodialysis, we examined autonomic nervous function in rest prior to a next dialysis session in 28 patients on chronic intermittent haemodialysis. The aim was to compare intradialytically hypotensive with stable patients to assess whether blood pressure regulating mechanisms were related to basal autonomic function, assessed as heart rate variability (HRV) tested by means of the deep breathing test, the lying-to-standing test, and the Valsalva maneuver. Impedance cardiography was used to determine stroke volume and cardiac output during dialysis. In addition, blood pressure was registered automatically and systemic vascular resistance calculated. Blood volume variation was monitored by an on-line optical device. Intradialytic hypotension was observed in 10 patients (36%). Systemic vascular resistance in hypotensive patients decreased considerably (-14.0+/-5.9%), while it increased in stable patients (+9.9+/-4.6%, p = 0.004). Heart rate rose significantly in hypotensive patients (11.5+/-3.8%) in comparison to stable patients (-0.2+/-2.8%, p = 0.02). However, no significant differences in autonomic function were observed between hypotensive and stable patients. Although both groups showed impaired autonomic function, no significant correlation between changes in haemodynamics during dialysis and autonomic function at rest could be ascertained. In conclusions, hypotension during haemodialysis is not related to a patient's autonomic function at rest. This suggests that structural neuronal differences are not responsible for the severe decrease in systemic vascular resistance in intradialytic hypotension.