Monitoring of irrigating fluid absorption during transurethral prostatectomy. A study in anaesthetised patients using a 1% ethanol tag solution.

A simple, reliable method to detect absorption of irrigating fluid during transurethral prostatectomy is to tag irrigating fluids with 1% ethanol and monitor expired breath ethanol concentrations. This method correlated well (n = 0.79) with other existing methods of absorption monitoring in 20 anaesthetised patients. Ethanol (1%) tagging does not alter the optical quality of the irrigating fluid and is harmless to the patient. The technique is non-invasive, repeatable, cheap and gives instant results. It can be used in anaesthetised or awake patients and can detect absorption of as little as 100-150 ml in any 10-minute period.

Nuclear cataract--a microradiographic study.

Nuclear cataract is a common type of senile cataract characterized by an increased turbidity and often a yellow to brown pigmentation of the nucleus. Twenty-one human lenses with different degrees of nuclear turbidity were, after intracapsular cataract extraction, examined by a quantitative microradiographic technique. The dry mass concentration was determined along the lens axis, and revealed an overall distribution similar to the normal lens. The concentration increased from the poles towards the center of the lens, to reach a mean level of 0.47 g.cm-3 (range 0.38-0.55). Though the appearance of the nucleus as well as the dry mass were relatively uniform. In addition, different types of formations with reduced or increased dry mass were found in the nucleus. The location of these formations are described and their nature discussed.

Dynamic light scattering in the intact rabbit lens. Its relation to protein concentration.

The physical-chemical properties of highly concentrated protein systems as seen in the lens are poorly understood. Using the technique of dynamic laser light scattering spectroscopy, the authors have determined changes in the dynamics of lens proteins from the intact rabbit lens as a function of position and age. The authors have identified two heterogeneous populations of mobile scatterers with relaxation times of less than 0.5 msec and greater than 1 msec. A decrease in scattered light intensity at 90 degrees, an increase in protein concentration, and aging are associated with lengthening of the relaxation times of the less mobile population of scatterers. This data provides evidence for the existence of a gel-like structure of the lens proteins.

Nuclear vacuoles in nuclear cataract.

The human lens nucleus has always been described as a homogeneous part of the lens, and if any distinct opacities are found, these are considered to be congenital. However, in lenses with nuclear cataract, both of senile type and those induced by hyperbaric oxygen, we have found relatively transparent vacuoles in the nucleus of similar appearance as cortical vacuoles. In cataracts induced by hyperbaric oxygen the vacuoles were reversible to some extent. The vacuoles have been investigated with slit-lamp photography and quantitative microradiography. Nuclear vacuoles were found in 11 out of 25 patients treated with hyperbaric oxygen compared to 19 out of 100 pre-operatively examined senile nuclear cataracts. In the microradiographs the vacuoles appeared as dark rounded areas with a lower dry mass content (approximately 0.30 g X cm-3) than the surroundings (approximately 0.50 g X cm-3).

Selenium-induced cataract--a correlation of dry mass content and light scattering.

Selenium-induced cataracts in young rats were used to compare light scattering and dry mass concentration along the lens axis. Selenium-treated rats and control rats were examined 1, 2, 4 and 6 days after subcutaneous injection of selenium or 0.9% NaCl. The development of nuclear cataract was followed with a Scheimpflug slit-lamp camera. Light-scattering was determined by densitometry of the negatives taken by the Scheimpflug camera. Dry mass concentration was determined by quantitative microradiography of the extracted lenses. Increasing light scatter was seen from day 2 to day 6. The dry mass concentration, however, was not changed until day 6. Two distinct zones were found surrounding the center of the nucleus, one with increased and one with decreased dry mass. The rapid changes in dry mass concentration were probably caused by shifts in water distribution within the lens. Similar zones of hydration have also been found in human senile nuclear cataract. Selenium-induced cataract in the rat is discussed in relation to human nuclear cataract.

Nuclear cataract and myopia during hyperbaric oxygen therapy.

The effect on the human lens of prolonged hyperbaric oxygen therapy is reported. Eye examinations were given to 25 patients before, during, and after a series of 150 or more exposures to hyperbaric oxygen. All patients changed refraction in the direction of myopia during treatment. Fifteen of the patients had clear lens nuclei before treatment. Seven of these developed a nuclear cataract with reduced visual acuity during treatment. Reversible lens myopia has previously been noticed as a side effect of exposure to hyperbaric oxygen, but the cataractogenic effect in man has not been reported by other workers. This report strongly supports the theory of an oxidative damage to the lens proteins as a cause of nuclear cataract.

Atopic cataract: changes in the lens epithelium and subcapsular cortex.

Two lenses with atopic cataract, one from a 33-year-old man and one from a 50-year-old man, were examined by light and electron microscopy. The younger man had an anterior polar cataract and the older a subcapsular opacification of the entire subcapsular cortex. In the younger lens the epithelial cells in front of the anterior opacity were extremely large and contained an increased number of mitochondria. In the older lens epithelial cells were missing centrally. These morphological changes probably reflect a malfunction of the lens epithelium.