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Biomedical subjects

R J Simmons

Publications and source records attributed to R J Simmons.

At least 55 records · Page 3Linked to original sources
PubMed1985

Laser trabeculoplasty re-treatment.

Because of inadequate control of intraocular pressure, 26 eyes of 24 patients with primary and secondary open-angle glaucoma who had previously undergone argon laser trabeculoplasty were re-treated. Re-treatment was successful in ten eyes (38%); their average decrease in intraocular pressure was 10.2 mm Hg. After laser re-treatment, three eyes (12%) had marked increases in intraocular pressure, ranging from 10 to 37 mm Hg above baseline, necessitating urgent surgical intervention.

Adult↗
PubMed1985

Extracapsular cataract extraction and posterior chamber intraocular lens implantation in glaucomatous eyes.

Two hundred ninety-six eyes of 250 patients undergoing extracapsular cataract extraction (ECCE) with or without the implantation of a posterior chamber intraocular lens (PC-IOL) were studied. Pre-existing glaucoma of varying severity was present in 139 eyes and no known ocular pathology other than cataract in 157 eyes. During the first eight weeks following surgery, intraocular pressure elevations greater than or equal to 15 mmHg above baseline were seen in 23% of glaucomatous eyes controlled before surgery with glaucoma medications, in 39% of glaucomatous eyes controlled before surgery with argon laser trabeculoplasty, and in only 3% of nonglaucomatous eyes. The implantation of a PC-IOL did not influence the incidence of postoperative intraocular pressure (IOP) elevations. Among glaucomatous eyes with severe preoperative visual field loss (split fixation or central island less than or equal to 10 degrees), 9.7% had worsening of visual field after surgery. Open angle glaucoma of unclear etiology developed in 1.4% of normal eyes following uncomplicated ECCE with PC-IOL implantation. Surgical techniques the authors have found useful in glaucomatous eyes undergoing ECCE with PC-IOL implantation are discussed.

Aged↗
PubMed1985

Shock-wave effect on anterior segment structures following experimental neodymium:YAG laser iridectomy.

The short-pulse laser may prove superior to the argon laser in producing noninvasive iridectomies. Little is known of the effects of the laser shock-wave on anterior segment structures adjacent to the iris. To investigate this question, iridectomies were produced in two owl monkeys using a neodymium (Nd):YAG laser and tissues were evaluated by light microscopy and scanning and transmission electron microscopy. For purposes of comparison, one eye received an iridectomy produced by an argon laser. Results indicate that while clean iris colobomas can be produced with a well-focused Nd:YAG laser, its shock-wave affects tissues in both the trabecular meshwork and corneal endothelium if the iridectomy is located within 0.8 mm of the limbus. No damage to the trabecular meshwork or corneal endothelium was evident after the argon laser iridectomy.

Animals↗
PubMed1985

Effect of pilocarpine in treatment of intraocular pressure elevation following neodymium: YAG laser posterior capsulotomy.

A prospective study was conducted in 30 eyes of 30 patients to determine if pilocarpine would prevent increased intraocular pressure following Q-switched neodymium (Nd):YAG laser posterior capsulotomy. Fifteen eyes were given pilocarpine 4%, immediately following laser therapy and every hour until bedtime. Fifteen eyes served as untreated controls. Our results show that without prophylactic therapy, 10 of 15 eyes (67%) had a post-laser intraocular pressure (IOP) elevation of greater than 10 mmHg, while only one of 15 (6.6%) of the pilocarpine-treated eyes had a rise of that magnitude. The facility of outflow was reduced by 42% in the untreated eyes in contrast to an increase of 3% in those eyes treated with pilocarpine. Thus, pilocarpine 4% is effective in reducing the incidence and magnitude of elevated IOP following Nd:YAG posterior capsulotomy.

Cataract Extraction↗
PubMed1985

Coaxial radio frequency (RF) diathermy in anterior segment surgery.

Modern ophthalmic microsurgery, particularly cataract extraction, trabeculectomy, and other forms of glaucoma filtration surgery, has been characterized by ever increasing precision. The use of radio frequency (RF) currents for cautery of blood vessels in anterior segment microsurgery has several advantages over other methods widely employed, including the bipolar cautery. A coaxial monopolar underwater diathermy probe, which operates with RF current has been specifically developed for anterior segment microsurgery and has proved vastly superior in cataract surgery, trabeculectomy, and full thickness glaucoma filtration procedures.

Anterior Eye Segment↗
PubMed1985

Anterior chamber washout for traumatic hyphema.

A surgical approach that involves paracentesis and gentle anterior chamber washout and minimal surgical trauma is presented for dealing with traumatic hyphema. This technique taught by Dr. Paul Chandler produces excellent results and is safe, simple, and without need for elaborate instrumentation.

Adolescent↗
PubMed1984

Argon laser trabeculoplasty as initial therapy for glaucoma.

Argon laser trabeculoplasty (ALT) was used as the initial treatment in 30 eyes of 20 patients with uncontrolled open-angle glaucoma in Egypt. None of the patients had received previous medical or surgical therapy. The average reduction of intraocular pressure with ALT alone was 10.1 mm Hg. Medical and surgical glaucoma therapy was avoided in 83% (25 eyes) of the treated eyes during an average follow-up period of 7 1/2 months. The data indicate that ALT can be used as a safe and effective initial treatment for glaucoma in developing countries where socioeconomic factors make the medical treatment of glaucoma impractical.

Developing Countries↗
PubMed1984

Pupillary and iridovitreal block in pseudophakic eyes.

Twenty-six cases of pupillary and iridovitreal block in pseudophakic eyes are reported. Although ten patients presented with acute angle closure glaucoma, the majority were asymptomatic and had normal intraocular pressures. While cure was finally achieved in all cases, recurrence of block occurred in six eyes as late as two months after initial successful treatment. A variety of therapeutic modalities including argon laser iridectomy, argon laser gonioplasty (iridoplasty), surgical iridectomy, surgical vitrectomy, Q-switched Nd:YAG laser iridectomy and Nd:YAG laser photodisruption of the anterior vitreous face were needed. Despite successful relief of pupillary and iridovitreal block in these eyes with no evidence of glaucoma prior to cataract and lens implant surgery, four eyes developed eight or more clock hours of peripheral anterior synechiae, and nine eyes continue to require chronic medical therapy for glaucoma.

Aged↗
PubMed1984

Potentiation of anchorage-independent colony formation by sodium polyanethol sulphonate.

Sodium polyanethol sulphonate (SPS) when incorporated into rat erythrocyte lysate (REL) containing semi-solid agar medium at 1 mg ml-1. markedly enhanced colony formation by a number of anchorage-independent cell lines. REL usually needed to be included for the expression of SPS induced potentiation as in its absence SPS was generally cytotoxic. Studies suggested that SPS reduced the lag prior to colony initiation resulting in the earlier appearance of colonies and in a higher cloning efficiency. The effectiveness of SPS in potentiating colony formation by responsive cell lines was markedly influenced by the species of serum and to a lesser extent by differences between individual batches. Enhancement by SPS was greater with poorer foetal calf serum (FCS) batches than with better. This effect may have been partly due to SPS interfering with the action of a growth inhibiting serum component, possibly a lipoprotein. Studies in which delipidated FCS was substituted for normal FCS suggested that SPS was also able to compensate for the lack of a growth-promoting lipid component. Binding studies showed that initially 125I-SPS bound equally well at 4 degrees C and 37 degrees C with continued labelling occurring only at 37 degrees C. Autoradiography of cells labelled at 37 degrees C for 24 h revealed the presence of intracytoplasmic 125I-SPS.

Agar↗
PubMed1984

Effects of hypoxia on the kinetic and morphological characteristics of human melanoma cells grown as colonies in semi-solid agar medium.

An investigation was made of the cell populations that occur in the sequential strata of human melanoma ( MM96 ) colonies. Colonies were either grown for the full duration of culture in a 'physiological' atmosphere of 5% O2 (unperturbed colonies), or grown in this atmosphere followed by a final incubation in a hypoxic atmosphere of less than 0.1% O2. Both autoradiographic and ultrastructural studies indicated that cell changes similar to those which occur successively in monolayer cultures experiencing nutritional deficiency, exist concurrently in the sequential strata of the larger unperturbed colonies. At the margin with the necrotic core, approximately half of the cells showed morphological changes associated with death by apoptosis. The other half were undergoing necrosis. Observations on colonies incubated for the final 24 or 48 h in a hypoxic (less than 0.1% O2) atmosphere showed that many of these cells, although otherwise well preserved, developed oedema complicated by cytoskeletal rupture and extrusion of areas of damaged cytoplasm within membrane-bound vesicles. Although sudden-onset hypoxia did not appear to precipitate cell death in small colonies previously lacking a necrotic core, large colonies suffered a marked reduction in the width of their viable rims. Cell death under this circumstances was by necrosis, the same mode of death as occurs with infarction. The study indicated that apoptosis was associated with sub-acute cell death as occurs with progressive nutrient depletion and catabolite accumulation, whereas necrosis was associated with acute cell death as seen in previously compromised cells subject in addition to sudden-onset hypoxia.

Agar↗
PubMed1983

Relationship of patient age and tolerance to carbonic anhydrase inhibitors.

A retrospective review of the records of 222 patients indicated a significantly higher incidence of long-term tolerance to carbonic anhydrase inhibitors among patients 40 years of age or less than in older patients. This finding indicated that since argon laser trabeculoplasty and conventional glaucoma surgery have low rates of success in young individuals, it seems prudent to consider carbonic anhydrase inhibitors as part of long-term maximum medical therapy particularly in younger individuals unless specific contraindications exist.

Adolescent↗
PubMed1983

Pancreatin-EDTA treatment affects buoyancy of cells in Cohn fraction V protein density gradients without residual effect on cell size.

The buoyancy of suspension-grown Mastocytoma P815 X-2 cells in albumin-rich Cohn fraction V protein (CFVP) density gradients was found to be affected by prior incubation of the cells in pancreatin-EDTA salt solution. Whereas in pH 5.2 CFVP, pancreatin-EDTA treated cells behaved as if of reduced density when compared with the control 'undigested' group, in pH 7.3 CFVP they behaved as if of increased density. By contrast, pancreatin-EDTA treatment had no effect on the buoyancy of mastocytoma cells in polyvinylpyrrolidone-coated colloidal silica (PVP-CS, Percoll T.M.) density gradients of either pH 5.2 or pH 7.3. As cell size determinations failed to reveal alterations in cell size either as a direct result of pancreatin-EDTA treatment or as a combined consequence of such treatment and exposure to CFVP either with or without centrifugation, a mechanism involving a change in cell density other than during the centrifugation process itself seems unlikely. Binding studies employing 125I-CFVP, although indicating that CFVP bound to cells at 4 degrees, failed to reveal a pancreatin-EDTA treatment-related difference in the avidity of this binding. Although the mechanism of the pancreatin-EDTA-induced buoyancy shift in CFVP remains obscure, the absence of such an effect in PVP-CS suggests that the latter cell separation solution may more accurately be used to determine cell density.

Animals↗