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Biomedical subjects

J L Jay

Publications and source records attributed to J L Jay.

63 records · Page 4Linked to original sources
PubMed1980

Characteristics of reduction of intraocular pressure after trabeculectomy.

The change in intraocular pressure achieved after 98 trabeculectomy operations performed on 70 patients with primary open-angle glaucoma was analysed. The reduction was proportional to the untreated preoperative pressure, and the results indicated that a first trabeculectomy reduced the intraocular pressure to between 16 and 20 mmHg irrespective of its initial level. Cases which required medical therapy for final pressure control after surgery showed a distribution of initial intraocular pressure similar to those not requiring such therapy. In addition, these cases were reduced to a level of pressure only slightly above the arbitrary figure of 20 mmHg before medical therapy was added, and were therefore considered almost to have reached the normal physiological range. Cases submitted to a second trabeculectomy are discussed, including 2 cases with unexplained acute open-angle glaucoma some months after the first operation.

Female↗
PubMed1979

Trabeculectomy. Its role in the management of glaucoma.

This report describes the changes in intraocular pressure, visual fields, and visual acuity after 108 trabeculectomy operations for various types of glaucoma. Postoperative follow up ranged from 1 1/2 to 3 years and the consequences of any complications were assessed. Trabeculectomy was found to be a relatively safe and effective procedure and may be recommended at an early stage in glaucoma management rather than as a last resort.

Glaucoma↗
PubMed1978

Effects of intraocular miotics on cultured bovine corneal endothelium.

Two cases of severe corneal oedema occurred after the use of intraocular pilocarpine. Experimental investigations were conducted with cultured bovine corneal endothelial cells exposed for 5 minutes to 1% pilocarpine solutions of varying composition. Cells were destroyed in solutions not isotonic with aqueous humour, and calcium-free ionic solutions caused loss of cell adhesion without loss of viability. Low pH or the presence of 1% pilocarpine had no detectable effects; 1% acetylcholine chloride in 5% mannitol (Miochol) also caused cell destruction, and this preparation was found to be considerably hypertonic. The minimum requirements for the formulation of intraocular miotics are discussed.

Acetylcholine↗
PubMed1976

Dacryolith formation around an eyelash retained in the lacrimal sac.

A dacryolith was discovered in the lacrimal sac during a dacryocystorhinostomy for chronic dacryocystitis in which there was mucocele formation. Morphological examination confirmed the presence of an eyelash at the centre of the stone and electron microscopy demonstrated the presence of fungi (Candida sp.) in a matrix which was of markedly vairable morphology. The mechanism by which a hair enters the punctum and passes along the canaliculus may be attributed to the step-like pattern of ridges on the surface of a hair. The directional nature of these ridges dictates preferential movement towards the root end of the hair and prevents movements in the opposite direction.

Calculi↗
PubMed1975

Effect of benzalkonium chloride on the stability of the precorneal tear film in rabbit and man.

Benzalkonium chloride, a surface-active preservative commonly used in eyedrop preparations, has been shown to hasten the drying of the precorneal tear film. In the rabbit, 0.01 per cent benzalkonium (the concentration usually employed as a preservative) shortened the time required for the appearance of dry spots on the corneal surface by a factor of about four. In man, an approximately twofold hastening was demonstrated. This effect is thought to preclude the use of this substance as a preservative in eyedrop preparations for use as local anaesthetics.

Adult↗
PubMedDate not supplied

Comparison of repeatability of the multifocal electroretinogram and Humphrey perimeter.

Functional mapping of the retina by multifocal electroretinographic recordings is now possible. We compared the normal range, repeatability and response topography of this new technique with conventional static Humphrey perimetry to assess its suitability in clinical practice. The multifocal technique was performed on 60 age-matched controls. Measures of repeatability and reproducibility were obtained. Results were then compared with those obtained from a customized perimetry test. In both tests the coefficients of repeatability were found to decrease with eccentricity. The inherent measurement variation between techniques was comparable. Overall system variation indicates that the technique could be a useful tool at the clinical level.

Computer Graphics↗
PubMedDate not supplied

The effect of filter bandwidth on the multifocal electroretinogram.

The effect of filter bandwith on the multifocal electroretinogram was assessed by means of theoretical calculation, electronic simulation and real multifocal electroretinogram recordings. Waveform distortion by high-pass filtering on simulated square waves, normal electroretinogram waveforms and negative electroretinogram waveforms was demonstrated. The theory of the effect of differentiation on electroretinogram waveform shape by electronic filtering indicates that little effect would be observed by changing the input filter cut-off for normal electroretinographic waveform shapes. However, negative electroretinogram waveforms are differentiated when the high-pass filter setting is increased. The differentiation effect artificially recreates a positive component that could be mistaken as a b-wave component. To eliminate this effect when recording multifocal electroretinograms, a high-pass filter setting of less than 1 Hz should be used to preserve the true electroretinographic waveform shape.

Computer Simulation↗
PubMedDate not supplied

Placement of aortic valve bioprostheses in sheep via a left thoracotomy. Implantation of stentless porcine heterografts.

Juvenile sheep provide a good model for assessing the efficacy of antimineralization techniques because of their rapid calcification of bioprosthetic valves. Stentless bioprosthetic valves are under evaluation for possible improved durability as aortic valve replacements. A left thoracotomy approach for aortic valve implantation, which facilitates intraoperative and postoperative hemodynamic data collection, has been developed and refined in 13 sheep. A critical feature of this technique is a partial rib resection that creates a soft tissue acoustic window to improve postoperative transthoracic echocardiographic examination. This allows both quantification of valvular gradients and qualitative assessment of valve leaflet motion and calcification. Excellent correlation was observed between the intraoperative invasive valvular gradients and the postoperative echocardiographic gradients available in four animals (mean gradient r = 0.96, p = 0.003; peak gradient r = 0.98, p = 0.0004). This is an excellent technique for serial postoperative noninvasive evaluation of valve prostheses implanted in the aortic position.

Animals↗