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Biomedical subjects

D R Sanders

Publications and source records attributed to D R Sanders.

At least 73 records · Page 4Linked to original sources
PubMed1983

Visual, refractive, and keratometric results of radial keratotomy.

Prospective evaluation of radial keratotomy was conducted on 156 consecutive eyes of 101 patients. Before surgery, mean spherical equivalent (SE) was -5.0 diopters and uncorrected distance acuity was 20/200 or worse in 96% of eyes. All eyes were examined six months after surgery. Overall six-month postoperative distance acuity was 20/20 in 43% and 20/40 or better in 73% of eyes; 51% of eyes were within 1.0 D of emmetropia; mean change in SE was +4.8 D. When preoperative myopia was less than 6.0 D, six-month uncorrected acuity was 20/20 in 53% and 20/40 or better in 84% of eyes; 63% were within 1.0 D of emmetropia. Visual, refractive, and keratometric findings appeared stable at six months. Predictability appeared best when preoperative myopia was less than 6 D. Complications were few, none resulted in reduced best-corrected acuity, and most were transient and/or well tolerated. In this series, radial keratotomy appeared safe short-term. Ongoing evaluation is being conducted to determine long-term safety and efficacy.

Adult↗
PubMed1983

Comparison of empirically derived and theoretical aphakic refraction formulas.

A formula for predicting aphakic refraction from axial length and keratometry measurements was derived from 120 cases, using linear regression analysis, as follows: Psp = 80.4 - 1.65L -0.7K, where P indicates aphakic spectacle power in diopters; L, axial length in millimeters; and K, result of keratometry in diopters. The prediction accuracy of this simple formula was compared with that of a complex theoretic formula based on geometric optics in 205 additional cases. The prediction accuracy of the theoretic and linear regression-derived formulas was virtually identical despite their differences in complexity and derivation. The differences and similarities between theoretic-derived and regression-derived aphakic and pseudophakic prediction formulas are discussed.

Aphakia↗
PubMed1983

Aqueous penetration of oral and topical indomethacin in humans.

Aqueous humor and serum indomethacin levels were determined following administration of the drug orally, as a topical 1% aqueous suspension and as a topical 1% oil suspension. Patients receiving indomethacin orally had a mean aqueous humor level below the lower limit of sensitivity of the assay, which is also below the level known to inhibit prostaglandin synthesis in vitro and a mean serum level of 642 ng/mL. Patients receiving the topical 1% aqueous suspension had a mean aqueous level of 198 ng/mL and no detectable serum level. Patients receiving the topical 1% oil suspension had a mean aqueous level of 429 ng/mL, which was significantly higher than that of the aqueous suspension. Both topical suspensions yield levels that are able to inhibit prostaglandin synthesis. Higher aqueous levels with no detectable blood levels (and thus negligible potential for systemic toxic effects) make the topical route of administration preferable to the oral route.

Administration, Oral↗
PubMed1983

A comparison of carbon black with soot.

Carbon black is frequently confused with soot. In order to clarify the distinction between these materials, we have examined 6 carbon blacks and 18 samples of soot. Carbon black is composed of turbostratic colloidal aggregates which we call aciniform carbon (AC). Chimney soots from domestic wood or coal fires contain very little AC, while in diesel soots the solid particulates are essentially all AC. All soots examined contain much more extractable organic material and/or ash than does carbon black. Ames Salmonella assays were carried out on solvent extracts. The results were calculated as net revertants per mg of the original soot or carbon black. On this basis, the majority of the soot extracts assayed were at a much higher level of mutagenicity than any of the carbon black extracts. For several reasons, even greater differences in mutagen availability would be expected if the unextracted materials were compared in vivo.

Air Pollutants↗
PubMed1983

The results of posterior chamber lens implantation.

We studied 1,216 consecutive cases where the surgeon's intent was to implant a posterior chamber lens. In 37 cases, the surgeon elected to put in an anterior chamber lens because of events occurring at the time of surgery. In no instance was the intraocular lens procedure aborted and a lens not implanted. In the 37 cases implanted with anterior chamber lenses, 76% had a final visual acuity of 20/40 or better. In the 1,179 cases that had posterior chamber lenses implanted, 90% had visual acuity of 20/40 or better, and only 1% had worse than 20/400 vision. Senile macular degeneration accounted for over one-half of the 104 patients with a visual acuity of 20/40 or worse. Visual results appeared to be age related; 96% of patients who were less than 75-years-old achieved an acuity of 20/40 or better, whereas only 80% of those over 75 years achieved this level. Our results suggest that extracapsular extraction with posterior chamber lens implantation is safe and provides good visual results.

Aged↗
PubMed1983

Serial corneal endothelial cell loss with lathe-cut and injection-molded posterior chamber intraocular lenses.

We compared endothelial cell loss of patients implanted with lathe-cut posterior chamber lenses and those implanted with injection-molded lenses over a three-year postoperative period. Results were based on more than 2,500 measurements of corneal endothelial density. Although the technique of cataract extraction (anterior chamber phacoemulsification, posterior chamber phacoemulsification, or planned extracapsular extraction) significantly affected cell loss (P less than .01), the type of implant (lathe-cut or injection-molded) did not. Significant continuing endothelial cell loss did not occur during the first three postoperative years with injection-molded lenses. There was, however, a statistically significant 7% to 15% additional cell loss after surgery over the first two to three postoperative years with lathe-cut implants. There have been no cases of corneal endothelial decompensation developing after implantation of injection-molded or lathe-cut lenses. Because a standard field clinical specular microscope was used in this study, cell counting errors cannot be ruled out as a cause of these findings.

Cataract Extraction↗
PubMed1983

Secondary intraocular lens implantation.

The visual, refractive, and surgical results with 190 consecutive secondary implantations of an anterior chamber intraocular lens were studied. Best-corrected postoperative visual acuity was either better than or within 1 Snellen line of best-corrected preoperative vision in 87% of the cases. Vision worsened by more than two Snellen lines in ten cases (5%), which included three cases of retinal detachment and one case of ischemic optic neuropathy; however, in only one case (0.5%) did we feel that the visual decrease was directly attributable to the secondary implantation procedure. We believe that secondary intraocular lens implantation can improve functional visual acuity in aphakic patients, especially those unable to tolerate aphakic correction with contact lenses or spectacles.

Adult↗
PubMed1983

Studies on the blood-aqueous barrier after argon laser photocoagulation of the iris.

Breakdown and re-establishment of the blood-aqueous barrier (BAB) was studied following laser irradiation to the rabbit iris by quantitating leakage of protein, fluorescein, and fluorescein-labeled dextran (FLD-70, MW 70,000) into the aqueous humor. Breakdown of the BAB was more prolonged in pigmented than albino animals, possibly due to the increased laser energy absorbed by the pigmented iris. Fluorophotometry appeared to be a more sensitive method for evaluating BAB breakdown than aqueous protein measurements, and small molecule leakage (fluorescein) appeared to be more sensitive than macromolecule leakage (FLD-70). The noninvasive method of evaluating the BAB proved equally as effective as measuring aqueous protein content in assessing the sensitivity of laser-induced trauma to the ameliorating effect of the nonsteroidal anti-inflammatory agent indomethacin.

Animals↗
PubMed1982

Breakdown and reestablishment of blood-aqueous barrier with implant surgery.

Preoperative and serial postoperative anterior chamber fluorophotometry was performed after oral administration of fluorescein sodium in patients undergoing extracapsular cataract extraction combined with intraocular lens implantation. In placebo-treated eyes, the blood-aqueous barrier was reestablished at three months after surgery. The administration of topical indomethacin before and after surgery markedly decreased aqueous fluorescein concentration, and the blood-aqueous barrier was reestablished within five weeks. Because all patients were given sub-Tenon's injection of steroids immediately after surgery and intensive topical steroid therapy postoperatively, the effect of topical indomethacin was additive to or synergistic with steroids. The addition of topical indomethacin caused a small but statistically significant increase in the postoperative intraocular pressure; this effect lasted nine weeks.

Administration, Topical↗
PubMed1982

Planned extracapsular extraction versus phacoemulsification with IOL implantation: a comparison of concurrent series.

We compared a concurrent series of patients undergoing Shearing posterior chamber lens implantation combined with planned extracapsular extraction (PEC) or with phacoemulsification (KPE). The visual results were significantly better with KPE than with PEC, even after adjustment for differences in patient age, sex, and followup. The KPE procedure averaged 0.27D less cylinder per case than the PEC procedure. The KPE procedure, however, was significantly more traumatic to the corneal endothelium, as estimated clinically at the time of surgery and corroborated by prospective specular microscopy. The surgeon observed no significant differences between postoperative corneal reaction or Descemet's folding in the two groups, although he clinically estimated the anterior chamber reaction to be greater in the PEC patients.

Adult↗
PubMed1982

A comparison of the Digital Biometric Ruler-300 and Echo-oculometer-3000: a report of two hundred cases.

Axial length measurements in 200 patients were performed with the Digital Biometric Ruler (DBR) and the Echo-oculometer with (Echo-osc) and without an oscilloscope (Echo). Measurements taken with the DBR and Echo-osc correlated better with each other than either did with the Echo measurements. In 32% of cases, the DBR and Echo-osc measurements differed by 0.4 mm or more, corresponding to a difference in predicted implant power of 1 diopter (D) or more. In 8% of cases, the measurements differed by 0.8 mm or more, corresponding to a difference in predicted implant power of 2D or more. In spite of these differences in axial length measurement in individual patients, intraocular lens implant power using the SRKTM formula, could be accurately predicted to within 1D of spectacle correction in 75% to 82% of cases, and to within 2D of spectacle correction in 94% to 98% of cases using either the DBR or Echo-osc measurements. Based on the poor correlation of the Echo axial length measurements to the other two, and the poorer implant power prediction accuracy, we do not recommend the use of the Echo-oculometer without an oscilloscope.

Biometry↗
PubMed1982

Prophylaxis of pseudophakic cystoid macular edema with topical indomethacin.

A prospective double-masked study of 500 patients was performed to assess the effect of topical indomethacin on the angiographic incidence of cystoid macular edema (CME) in patients undergoing intraocular lens implant surgery. All patients received either topical indomethacin or placebo before surgery and for nine months after surgery. All patients underwent planned extracapsular extraction (PEC) or posterior chamber phacoemulsification (PC-KPE). Implantation of a posterior chamber lens and a primary capsulotomy were performed in all cases. All cases received postoperative topical corticosteroids. Of the 500 cases, 390 (78%) underwent fluorescein angiography; most were performed between 2 1/2 and 5 months after surgery. The incidence of angiographically confirmed CME was significantly higher in the placebo-treated patients as compared to those treated with indomethacin (18.5% vs 9.6%; P = 0.04). Patients 60 years of age or older had a significantly higher incidence of CME than younger individuals (15% vs. 3.4%; P = 0.03). When corrected for the effects of drug regimen and age, by means of multiple logistic regression, there was no significant correlation between procedure (PEC vs. PC-KPE) and CME rate (P = 0.62). There was no significant difference in postoperative visual acuity between the indomethacin- and placebo-treated patients (P = 0.65).

Adrenal Cortex Hormones↗
PubMed1982

Monitoring for continuing endothelial cell loss with cataract extraction and intraocular lens implantation.

For a period of three years, more than 2,700 endothelial cell density measurements were performed in over 1,000 patients undergoing cataract extraction with and without intraocular lens implantation. We concluded the following from the data: (1) Significant cell loss occurred with all surgical procedures, averaging between 11.6% and 25.6%, depending on type of procedure and implant used; anterior chamber phacoemulsification without intraocular lens implantation caused the most cell loss. (2) Patients with Medallion suture implants produced by one of two manufacturers studied demonstrated statistically significant cell loss during the first (15.6% additional cells lost) and second (22.9% additional cells lost) postoperative years following the initial cell loss due to surgery. This evidence for continuing cell loss with the Medallion suture lens correlated with the clinical observation of an increasing incidence of late bullous keratopathy in these patients. (3) No other surgical procedure or implant type, including Choyce and Shearing implants and Medallion style lenses from another manufacturer, demonstrated any evidence of continuing endothelial cell loss following the initial loss due to surgery.

Cataract Extraction↗
PubMed1982

Dynamic changes in the organophosphate profile of the experimental galactose-induced cataract.

Dynamic changes in lens organophosphate metabolites during 24 hr incubation in 30 mM galactose media were measured with phosphorus-31 nuclear magnetic resonance spectroscopy. The following phosphates were quantitated from the intact crystalline lens: adenosine triphosphate (ATP), adenosine diphosphate (ADP), inorganic orthophosphate, alpha-glycerophosphate, phosphorylated hexoses and trioses, nicotinamide adenine dinucleotide, uridine diphosphoglucose and uridine diphosphogalactose, glycerol-3-phosphorylethanolamine and 3-phosphorylcholine, and an unidentified phosphorus-containing molecule. The temporal sequences of metabolic events that define the dynamic rates of accumulation or depletion of lens organophosphates reveal that the first event in the decline of the tissue upon galactose incubation is a net consumption of ATP, which occurs as a sigmoidal function with time and which is typified by a characteristic half-life of 18 hr. Alpha-glycerophosphate accumulated at an increasing rate with time, whereas ADP, inorganic orthophosphate, and the other organophosphates were essentially unchanged. Cataract formation in the subcapsular and superficial cortical regions was visible after 16 hr incubation in the experimental buffer. These findings support the hypothesis that alterations in the organophosphate levels of the lens are contributing factors to the initial formation of the experimental galactose cataract.

Adenosine Diphosphate↗
PubMed1981

Organophosphates of the crystalline lens: a nuclear magnetic resonance spectroscopic study.

We quantitated the concentrations of the principal organophosphate metabolites present in the intact crystalline rabbit lens, measured the intralens pH, and evaluated dynamic changes during 24 hr incubations, using phosphorus-31 nuclear magnetic resonance (P-31 NMR) spectroscopy. Tissue perchloric acid extracts prepared from these same lenses were analyzed by this technique to verify metabolite identifications and to quantitate the concentrations of the minor lens metabolites. Values for lens organophosphate concentrations, including three groups of previously unidentified phosphorus-containing substances, were established for freshly excised lenses, 24 hr incubated lenses, and lenses incubated in glucose-deficient media. Lens metabolite levels were not adversely affected by incubation in a medium previously shown to maintain lens clarity and ion transport capabilities. Conversely, lens incubation in glucose-deficient media induced significant metabolic changes characterized by a time-dependent decline in ATP, corresponding increases in ADP, inorganic phosphate, and phosphorylated hexoses. Cataract formation was noted after incubation in this medium. These findings support the hypothesis that alterations in the organophosphate levels of the lens actually preceded changes in the Na+ and K+ concentrations and therefore may be the "initiating factor" in formation of lens cataracts.

Animals↗
PubMed1980

Nitropyrenes: isolation, identificaton, and reduction of mutagenic impurities in carbon black and toners.

Extracts of selected xerographic toners and copies were found to be mutagenic in the Salmonella assay. The activity was independent of the xerographic hardware and process and was traced to nitropyrenes present as impurities in the carbon black, the toner colorant. Manufacturing process changes resulted in a substantial reduction of the nitropyrene content of the carbon black and thus in the mutagenicity of the corresponding toners. Nitropyrenes are potent frameshift mutagens, and possible mechanisms for their biological action are discussed.

Biotransformation↗