Search PubMed⌕ Search

Biomedical subjects

A C Neumann

Publications and source records attributed to A C Neumann.

At least 19 recordsLinked to original sources
PubMed1991

Improvement in visual acuity in chronic aphakic and pseudophakic cystoid macular edema after treatment with topical 0.5% ketorolac tromethamine.

Ketorolac tromethamine 0.5% ophthalmic solution treatment was compared to placebo treatment in 120 patients with chronic aphakic or pseudophakic cystoid macular edema (six-month or more duration of distance visual acuity of 20/40 or less and angiographic evidence of cystoid changes) during a four- to five-month double-masked, multicenter study in which patients were randomly assigned. A statistically significant improvement in distance visual acuity (two lines or more) was observed in the ketorolac-treated group as compared to the placebo-treated group after 30 days (P = .038), 60 days (P = .017), and 90 days (P = .008) of treatment. This improvement in visual acuity remained statistically significant one month after cessation of treatment (P = .001). Nine ketorolac-treated patients and two placebo-treated patients demonstrated a decrease in visual acuity one month after treatment was discontinued. Seven of the nine ketorolac-treated patients experienced an improvement in visual acuity after retreatment as compared to none of the placebo-treated patients. This study offers evidence for a more optimistic outlook in the medical treatment of chronic aphakic and pseudophakic cystoid macular edema.

Administration, Topical↗
PubMed1991

Hyperopic thermokeratoplasty: clinical evaluation.

A new procedure, hyperopic thermokeratoplasty (HTK), developed in the Soviet Union for the correction of hyperopia, uses controlled thermal burns of the corneal stroma with a retractable probe tip preset to penetrate the cornea at 95% depth. The coagulations are applied in a radial pattern for spherical hyperopia. Only the peripheral cornea is treated and the effect is titrated by varying the optical zone and number of rays. The thermal effect flattens the peripheral cornea and steepens the central cornea. In this report, we prospectively evaluated the refractive results of a group of 61 HTK patients. Mean preoperative spherical equivalent was 3.9 diopters (D). Mean follow-up to date is 5.2 months, with 44% of cases evaluated at six months and 31% at one year. The initial effect of surgery (at one day) was a mean decrease in hyperopia of 6.0 D (standard error of the mean [S.E.] = 0.3 D), resulting in a mean spherical equivalent of -2.1 D (S.E. = 0.2 D). There was a steep regression of effect between one day and two months at which point average refraction was close to emmetropia. After two months, there was a gradual but continuing regression of effect, leveling off after six months. At five to six months, 63% of cases were undercorrected by at least a diopter; at 9 to 12 months, 83% of cases were undercorrected. The overall change in spherical equivalent at each time increased as optical zone size decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Endophthalmitis investigative protocol: a plan for source identification and patient protection.

A survey of randomly selected ophthalmic outpatient surgical facilities revealed a lack of established investigative protocols to follow when postoperative endophthalmitis occurs. The survey also provided information about the incidence of endophthalmitis, the microorganisms encountered, and the precautions used to prevent postoperative infections. We present an endophthalmitis investigative protocol which provides a task list, investigation forms, incidence log, and quality assurance measures to identify patients at risk and to minimize the risk of recurrence of this rare but serious complication of ophthalmic surgery. This standardized protocol will also assist in source identification when aseptic iritis occurs postoperatively. The purpose of this paper is to stimulate a dialogue which may result in an international standard for an endophthalmitis investigative protocol.

Ambulatory Surgical Procedures↗
PubMed1990

Effect of thermokeratoplasty on corneal curvature.

A cadaver eye model was used to evaluate and quantify the use of thermokeratoplasty for steepening the central cornea to correct hyperopia. Four groups of eye-bank eyes were treated with four separate surgical plans. Each plan involved the placement of controlled thermal burns (in the depths of the corneal stroma, using a cautery probe) applied in a radial pattern up to a premarked optical zone. The plans differed in the sequence of surgical steps. All plans progressively added radials and applications (to decrease optical zone) in various sequences. Corneal curvature was measured at baseline and at each surgical step. As more surgery was done within each plan, the corneas became progressively steeper. Total mean changes in corneal curvature ranged from 16.26 diopters to 19.76 diopters, depending on the plan. At each optical zone, as the number of radials increased, the effect increased. With progressively smaller optical zone size, the effect also increased.

Cornea↗
PubMed1989

Enhanced accuracy is necessary for refractive surgery instrumentation.

New optical zone markers, diamond knives, and gauge blocks were ordered from a random selection of manufacturers and inspected by an independent metallurgical engineer. This study revealed workmanship flaws and poor instrument accuracy. None of the 26 optical zone markers examined came with instructions as to whether the incisions were to be carried to or from the inside diameter or the outside diameter of the corneal impression made by the marker. Two markers had a 100 microns or greater error in their centering devices and one had a centering device off center by 210 microns. Two of the seven diamond micrometer knives had broken blade tips and uneven footplates; two knives had misaligned blades and uneven footplates, one knife had extremely roughly finished footplates, and one knife had a 100 microns error in its micrometer. All the knives had a wobble in the blade shaft upon advancement and had rounded footplates, making blade extension verification difficult. Five of seven blade gauges were accurate to within 10 microns; two had errors of more than 60 microns which could lead to incisions too deep or too shallow and micro- or macroperforations of the cornea during refractive surgery. It is recommended that all refractive surgery instruments be carefully inspected under a high power micron-level microscope at the time of purchase and routinely thereafter.

Keratotomy, Radial↗
PubMed1989

Advantages and limitations of current soft intraocular lenses.

We report our clinical experience with six soft intraocular lenses: (1) STAAR silicone, (2) CooperVision/Schlegel silicone, (3) IOLAB silicone, (4) Allergan Medical Optics (AMO) silicone, (5) Fyodorov silicone, and (6) Alcon hydrogel (IOGEL). We found that these soft intraocular lenses have several common design problems. The single-size design of five of the six soft lenses can lead to a windshield-wiper decentration effect in lenses too small for larger eyes. We observed several instances in which the one-piece lenses became decentered, subluxed, and vaulted anteriorly against the iris or posteriorly away from the iris as postoperative capsulozonular changes occurred. We found that the insertion methods for these soft lenses need refining to reduce the risk of intraocular damage and wound stretching if the lenses are to be folded and inserted through a small 3.0 mm to 3.5 mm incision. The surface and physical characteristics of these lenses may also require further study. We observed folding grooves, sebacium deposits, and rust from the insertion instrument on some lenses inside the postoperative eye and pigment dispersion associated with hydrogel lenses. We conclude that small diameter polymethylmethacrylate implants are the best choice for small incision cataract surgery at this time.

Cataract Extraction↗
PubMed1989

Refractive evaluation of astigmatic keratotomy procedures.

We evaluated the efficacy of three transverse incision astigmatic keratotomy procedures using a vector analysis that enabled us to determine the magnitude of the effect and the axis in which it occurred. These procedures were used for low levels of astigmatism (0.5 diopter [D] to 3.75 D): (1) staggered, radial-touching transverse (T) incisions, (2) non-radial-touching T incisions, and (3) T incisions with interrupted radial. Most procedures were performed in conjunction with radial keratotomy for spherical correction of myopia. The non-radial-touching T procedure was the least effective method of reducing astigmatism. The staggered, radial-touching T and T with interrupted radial procedures were equally effective in reducing over 93% (on the average) of the preoperative astigmatism. Of these two procedures, the T with interrupted radial procedure was the most accurate, with the effect of the surgery deviating less than ten degrees from the desired axis in over 70% of the eyes.

Adult↗
PubMed1989

Small incisions to control astigmatism during cataract surgery.

Astigmatic changes in three series of cataract surgical procedures were compared. Two series comprised eyes having phacoemulsification and implantation of a foldable silicone lens through a 3.0 mm to 4.0 mm incision or a 5.8 mm diameter polymethylmethacrylate (PMMA) lens through a 6.0 mm incision. The third series comprised eyes having a planned extracapsular cataract extraction (ECCE) procedure through a 10.0 mm incision and implantation of a PMMA posterior chamber lens. Surgically induced cylinder changes were compared by examining preoperative and postoperative dioptric cylinder power changes without regard to axis changes and by using vector analysis to compute induced cylinder for cases with axis changes. Both phacoemulsification series had similar mean induced cylinder levels, which were significantly less than mean induced cylinder in the ECCE group at both three and six months after surgery. Over 70% of the eyes in the two small incision phacoemulsification groups achieved an uncorrected visual acuity of 20/40 or better at three months, whereas only 28% of the ECCE group achieved that acuity. We concluded that the phacoemulsification procedure induced significantly less astigmatism and provided faster visual rehabilitation than the ECCE procedure. Furthermore, the use of small diameter PMMA IOLs inserted through small incisions minimized surgically induced cylinder in a way comparable to the use of foldable silicone implants, while maintaining good visual results with fewer postoperative complications.

Adult↗
PubMed1988

The relationship between indoor and outdoor Snellen visual acuity in cataract patients.

One hundred six cataractous eyes of 78 patients were evaluated to examine the relationship between indoor and outdoor Snellen visual acuity. While 81 of all cataractous eyes (76.4%) had Snellen visual acuities of 20/40 or better when tested indoors, only 33 eyes (31.2%) had 20/40 or better Snellen visual acuities when tested outdoors facing the sun. When tested indoors, only three eyes (2.8%) had Snellen visual acuities worse than 20/80, while 31 eyes (29.2%) had outdoor Snellen visual acuities worse than 20/80. Ten eyes (9.4%) had outdoor Snellen visual acuities worse than 20/200. Seventy-four eyes (69.8%) had outdoor visual acuities that were at least two Snellen lines worse than those measured indoors and 23 eyes (21.7%) had outdoor visual acuities that were at least five Snellen lines worse. The median difference between indoor and outdoor visual acuity was three Snellen lines. The need for increased precision in the ability to assess outdoor "real world" vision while in the ophthalmologist's examination room is discussed. Clearly, indoor Snellen visual acuity alone is insufficient to evaluate functional visual impairment in cataract patients.

Cataract↗
PubMed1988

The relationship between cataract type and glare disability as measured by the Miller-Nadler glare tester.

Cataract patients were tested for glare disability using the Miller-Nadler glare tester. Predicted outdoor visual acuity was then compared with the actual outdoor visual acuity. The Miller-Nadler glare test scores predicted actual outdoor visual impairment to within one Snellen line in 46.7% of the eyes, underestimated actual outdoor visual impairment by more than one Snellen line in 31.5% of the eyes, and overestimated outdoor visual impairment by more than one Snellen line in 21.7% of the eyes. Overall, 64.1% of the eyes had outdoor vision which was more closely predicted by their glare scores than by their indoor Snellen acuity. When the cataractous eyes were divided into three categories, eyes with pure nuclear sclerosis, eyes with nuclear sclerosis and posterior subcapsular opacities, and eyes with all other cataractous combinations, predictability differences were observed. Although we found that actual outdoor visual acuities were not precisely predicted by disability glare scores in a substantial proportion of our subjects, the glare scores were considerably more predictive than indoor Snellen acuity. Further development and field testing of glare testing devices as predictors of outdoor visual impairment is necessary.

Cataract↗
PubMed1988

Glare disability devices for cataractous eyes: a consumer's guide.

We evaluated five commercially available glare testers to determine how accurately each device predicted outdoor Snellen acuity in cataract patients. Predicted outdoor Snellen acuity was compared to actual Snellen outdoor acuity for the Miller-Nadler glare tester, the brightness acuity tester (BAT), the InnoMed true vision analyzer (TVA), the VisTech VCT 8000, and the EyeCon 5. All five devices were evaluated in a single series of eyes. We ranked the five glare testers as follows based upon their ability to predict outdoor Snellen acuity within one Snellen line: (1) BAT (73%), (2) TVA (69%), (3) VisTech VCT 8000 (56%), (4) Miller-Nadler (47%), and (5) EyeCon 5 (15%). All five devices were also evaluated for their capacity to provide false negative or false positive results and for testing time per eye, test difficulty level for the patient, versatility, upgrading capacity, examining room adaptability, and price. We concluded that glare testing of cataract patients is necessary to measure visual disability and that glare testing devices vary in their ability to predict outdoor vision.

Cataract↗
PubMed1988

Hexagonal keratotomy for correction of low hyperopia: preliminary results of a prospective study.

Fifteen sighted eyes of 11 patients had hexagonal keratotomy for the correction of low hyperopia. Mean preoperative hyperopia of +3.21 diopters (range +1.75 to +5.50) was reduced a mean of 2.16 diopters (range 0 to -3.25) and keratometry was increased a mean of +2.22 diopters (range +0.75 to +3.71). Follow-up averaged 9.5 months (range 2.0 to 17.5). Ten of the 15 eyes (67%) had at least six months follow-up. No eye had better than 20/80 uncorrected visual acuity preoperatively. Fourteen eyes (93%) had 20/80 or better uncorrected acuity at the most recent postoperative visit. Nine of the 15 eyes (60%) had uncorrected acuity of 20/40 or better. Refractive spherical equivalent appeared to stabilize by three months for most patients. Astigmatism was increased a mean of only +0.02 diopter and no serious complications occurred. Further follow-up is required to assess the safety and efficacy of hexagonal keratotomy for reducing low levels of hyperopia.

Astigmatism↗
PubMed1987

Phacoemulsification devices: a consumer's report.

This report deals with our evaluation of six phacoemulsification devices tested at the Neumann Eye Institute (two additional devices have been evaluated since this paper was presented at the ASCRS meeting). The devices were compared for operating cost of the first 1,000 cases, dependability, ease of usage, and level of safety for the patient.

Cataract Extraction↗
PubMed1987

Complications associated with STAAR silicone implants.

We compared the incidence of various complications in consecutive series of cases in which 76 eyes received STAAR silicone intraocular implants and 76 eyes received small incision IOLAB G708G polymethylmethacrylate (PMMA) intraocular implants. All surgeries were performed by the same surgeon employing the same phacoemulsification technique. A higher incidence of lens subluxation, lens repositioning, corneal edema, and elevated intraocular pressure was observed in the eyes receiving STAAR silicone implants than in the eyes receiving IOLAB PMMA implants. In addition, a YAG laser posterior capsulotomy could not be performed through several STAAR silicone RMX 1 model implants. An invasive pars plana posterior capsulotomy was necessary in these eyes. We also found that the STAAR silicone RMX 3 model implants were often pitted by the YAG laser during successful posterior capsulotomies. Despite these problems, the STAAR silicone intraocular lens group achieved corrected vision similar to the PMMA lens group.

Humans↗
PubMed1987

Phacoemulsification devices: a consumer's update.

This report extends a previous paper on the various characteristics of the most popular phacoemulsification devices. An evaluation of 11 devices by ten different manufacturers was attempted. Only five manufacturers of six devices agreed to critical evaluation or reevaluation. As in the previous report, the devices were compared for level of patient safety, dependability, efficiency, ease of usage, and operating cost for the first 1,000 cases. At the completion of this study, we ranked the nine devices evaluated over the past 17 months as follows: (1) United Surgical (Optikon) Systems Plus, (2) Optical Micro Systems (OMS), (3) United Surgical (Optikon) Phacotron, (4) CooperVision 10,000, (5) Site XTR, (6) CooperVision KCP, (7) CooperVision 9001, (8) Phakosystems CES 4000 and (9) United Sonics. To enhance the usefulness of this consumer's guide, we asked 40 experienced cataract surgeons what they wanted in the "ideal" phacoemulsification device. The opinions of 27 who responded are included.

Cataract Extraction↗
PubMed1986

Particulate and microbial contamination of intraocular irrigation solutions.

The risk of anterior chamber microbial or particulate contamination or both during extracapsular cataract extraction has increased because of the need for large volumes of irrigating solution during the procedure. I performed a clinical trial using an in-line microfiltration apparatus fitted with a 0.8 micron filter. After passing 500 ml volume bottles of each of six manufacturers' irrigating solutions through individual filters, a variety of particulate matter was observed to be trapped by the filter. In addition, I had samples of 500 ml bottles from each of seven manufacturers' irrigating solutions analyzed independently. This independent analysis involved the determination of particulate counts by Coulter counter analysis and photographic documentation of the particulate matter found in the samples. All the solutions were found to contain some particulate matter. The quantity found ranged from as few as 20 particles per ml to as many as 2,400 particles per ml. The results of this study support the use of an in-line microfiltration apparatus during planned extracapsular and phacoemulsification cataract surgery.

Bacteria↗
PubMed1984

Radial keratotomy: a comprehensive evaluation.

A prospective clinical investigation of radial keratotomy employing the Fyodorov method and instrumentation was initiated in March, 1980. The results of the first 147 eyes undergoing this surgical procedure for the reduction or elimination of myopia were analyzed one year following surgery. The mean preoperative, uncorrected visual acuity was finger counting vision and the mean preoperative myopic spherical equivalent was 5.33 diopters. The preoperative myopic refractive error ranged from 1.75 to 11.75 diopters. Radial keratotomy resulted in a mean uncorrected visual acuity of 20/35 with a mean reduction on myopia of 4.66 diopters. Eighty percent of the 147 eyes experienced 20/40 or better uncorrected vision. Sixty-eight percent of high myopia eyes (6.00 to 11.75 D) attained this level of uncorrected vision with a mean reduction of myopia of 6.23 diopters. Glare and variation of vision were the most frequently reported complications. A non-progressive endothelial cell loss of 5.2 percent was observed. The degree of preexisting myopia, patient age, fellow eye experience and surgeon learning curve significantly influenced the surgical result and facilitated the predictability of the procedure. Incision depth was directly related to surgical result. The low myopia group achieved stabilization of effect by six months while stabilization occurred later in patients with high degrees of initial myopia. Patient satisfaction was high and 78 per cent of the patients elected to undergo radial keratotomy in their fellow eye.

Adolescent↗