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Biomedical subjects

D Epstein

Publications and source records attributed to D Epstein.

At least 37 records · Page 2Linked to original sources
PubMed1995

Indications, results, and complications of refractive corneal surgery with lasers.

The use of lasers to correct refractive errors has become an established clinical procedure in many countries. Excimer laser photorefractive keratectomy (PRK) has been performed on an estimated 400,000 to 500,000 eyes worldwide. For myopia up to about 6.0 D, PRK appears to be generally safe, exhibiting acceptable accuracy, predictability, and stability. Complications of PRK can occur intraoperatively, and early or late postoperatively. For higher degrees of myopia, laser in situ keratomileusis may prove to be a more appropriate procedure, but long-term follow-up is needed. Hyperopic PRK and holmium:yttrium-aluminum-garnet thermokeratoplasty are still considered investigational methods, and for newer technologies, such as solid-state lasers, human trials are being launched.

Cornea↗
PubMed1995

[Photorefractive keratectomy (PRK). The limits of our knowledge].

The confines of our knowledge with respect to excimer laser photorefractive keratectomy are particularly manifest in two areas: the effects of the excimer on the corneal tissue, especially in the course of the wound healing process; and the optical aberrations caused by the laser treatment through structural alterations in a previously clear cornea. The criteria currently used to evaluate the outcome of excimer refractive surgery are not adequate. More stringent and nuanced assessments are needed to expand the frontiers of our knowledge.

Cornea↗
PubMed1994

Excimer retreatment of regression after photorefractive keratectomy.

Regression of effect is a well-established complication of excimer laser photorefractive keratectomy for the correction of myopia. In 17 eyes retreated with excimer photorefractive keratectomy, minimum follow-up time was six months. Mean (+/- SD) refraction at six months postoperatively was -0.97 +/- 2.10 diopters, significantly different (P < .01) from the pre-retreatment mean of -2.91 +/- 0.86 diopters. The 11 best eyes (six-month refraction < -1.00 diopter) had a mean refraction of +0.32 +/- 0.67 diopter. At six months after retreatment, 64.7% had an uncorrected visual acuity greater than or equal to 20/40, and 58.8% were within 1.00 diopter of emmetropia. Two eyes showed a loss of one to two Snellen lines at six months. There was no significant increase in mean haze after retreatment. While the percentage of eyes with uncorrected visual acuity greater than or equal to 20/40 and the percentage of eyes within 1.00 diopter of emmetropia were lower than in eyes which did not require retreatment, the results of this study indicate that the majority of photorefractive keratectomy regressions can be successfully retreated.

Adult↗
PubMed1994

Twenty-four-month follow-up of excimer laser photorefractive keratectomy for myopia. Refractive and visual acuity results.

PURPOSE: To evaluate the 24-month refractive outcome of excimer laser photorefractive keratectomy (PRK) performed on normal, sighted myopic eyes; and to assess the evolution of postoperative refraction, the accuracy of predicted correction, and the results in terms of uncorrected visual acuity. METHODS: Photorefractive keratectomy was performed on 495 eyes, with a preoperative refraction ranging from -1.25 to -7.50 diopters (D). Ablation zone diameters of 4.3 and 4.5 mm were used. All patients were treated with a standard topical steroid regimen postoperatively. Minimum follow-up time was 24 months. RESULTS: Mean refraction (spherical equivalent +/- standard deviation) at 24 months was -0.27 +/- 0.74 D, which was significantly (P < 0.01) different from the mean at 12 months (0.01 +/- 0.78 D). There was also a significant (P = 0.01) difference between the 12- and 18-month (-0.15 +/- 0.82 D) mean refractions. But there was no significant difference between the means at 18 and 24 months postoperatively. Subgroup analysis at 24 months showed that patients with low to moderate myopia (up to -3.90 D) had significantly better refractive outcomes than those with higher myopia. Also at 24 months, 91% of the eyes had an uncorrected visual acuity of at least 20/40, and 81.5% had an uncorrected visual acuity of at least 20/30. Correspondingly, 87.5% of the eyes were within 1.00 D of emmetropia, and 71.7% were within 0.50 D. Only 0.4% lost one line of best-corrected visual acuity, no eye lost two lines or more. CONCLUSIONS: Refraction after PRK is slow to stabilize, but appears to reach stability by 18 to 24 months after surgery. The refractive results are reasonably predictable and compare well with those achieved with radial keratotomy.

Adult↗
PubMed1994

Effect of postoperative steroids on the refractive outcome of photorefractive keratectomy for myopia with the Summit excimer laser.

To assess the role of topical steroids following excimer laser photorefractive keratectomy (PRK) for myopia, we compared the refractive outcome in 100 eyes that did not receive steroids in the immediate postoperative period (untreated eyes) with 100 eyes that were treated with topical dexamethasone for three months postoperatively. Photorefractive keratectomy was performed with the Summit laser, using 4.3 mm and 4.5 mm ablation zones. At three months after surgery, the untreated eyes had a mean refraction of -0.97 +/- 1.15 diopters (D), significantly different (P < .01) from the mean refraction (+0.46 +/- 0.74 D) of the steroid-treated eyes. By six months postoperatively, 86% of the untreated eyes had regressed to a myopia of at least 0.50 D, whereas only 23% of the steroid-treated eyes had regressed. In a second study, we compared the results in 25 patients whose first PRK eye was treated with steroids after surgery but whose second eye was not. At three months postoperatively, mean refraction in the steroid-treated eyes was +1.23 +/- 0.71 D, significantly different (P < .01) from the mean of -0.45 +/- 1.29 D in the untreated eyes. The refractive results in PRK eyes treated with the Summit unit and with relatively small ablation zone diameters showed that eyes that received dexamethasone postoperatively were less likely to regress to myopia.

Administration, Topical↗
PubMed1994

Photorefractive keratectomy for low myopia at 5 mm treatment diameter. A comparison of two excimer lasers.

The aim of the study was to evaluate the algorithm and surgical performance of two excimer lasers, the Summit Excimed 200 LA and the VISX 20/20, by assessing visual outcome parameters such as visual acuity and contrast sensitivity, and subjectively estimating dark vision performance. Furthermore, refractive results and centration of the surgically ablated area were assessed. Twenty patients were included in each group. The indications were myopia between -2 to -5 diopters allowing up to -0.75 diopters astigmatism. The treatment diameter was 5 mm. The postoperative treatment was topical dexamethasone for 3 months. The follow-up time was 12 months. The results showed a median refraction +/- 0.0 D in the Summit group and -0.5 D in the VISX group 12 months postoperatively. The uncorrected visual acuity was 0.5 (20/40) or better for 100% of the Summit treated eyes, whereas 85% of the VISX treated eyes achieved 0.5 (20/40) or better. The other visual qualities as contrast sensitivity, dark vision and centration of the ablation zone were the same in both groups. The slightly more myopic outcome of the VISX laser explains the poorer average uncorrected visual acuity in this group. We have, as a result of the refractive results, changed our algorithm in the VISX machine to achieve emmetropia. It is our experience that one should try to reach emmetropia in this young population.

Adult↗
PubMed1993

Excimer laser photorefractive keratectomy for myopia. Clinical results in sighted eyes.

PURPOSE: To evaluate the refractive results of excimer laser photorefractive keratectomy (PRK) performed on normal, sighted myopic eyes; to assess the role of postoperative topical steroid treatment in patients with PRK; and to study the regression of effect. METHODS: An argon fluoride 193-nm excimer laser was used. Photorefractive keratectomy was performed on 420 eyes with preoperative refraction ranging from -1.25 to -7.50 diopters (D). Minimum follow-up time was 12 months, and 194 of the eyes were followed for 15 months. Postoperative treatment generally consisted of topical dexamethasone for 3 months, but in a sub-study, some eyes were treated for only 5 weeks. RESULTS: Mean refraction (spherical equivalent +/- standard deviation) at 12 months was -0.04 +/- 0.84 D and at 15 months -0.22 +/- 0.78 D. At 12 months postoperatively, 86% of the eyes were within 1.00 D of emmetropia, at 15 months 87%. At 12 months, 91% of the eyes had an uncorrected visual acuity of at least 20/40, at 15 months 87%. Eyes treated with dexamethasone for 3 months regressed significantly less than those treated for only 5 weeks (P < 0.01). Dexamethasone also was effective in reversing regression later in the postoperative course. Eyes with preoperative myopia up to 4.90 D had significantly better refractive results at 12 months than eyes with myopia ranging from 5.00 to 7.50 D (P < 0.01). CONCLUSION: These data show that excimer laser PRK can correct myopia with good predictability. Results at 12 and 15 months tend to suggest stability of postoperative refraction. Regression of effect was more common in higher myopes. Topical steroids postoperatively seem to play a crucial role for the refractive result.

Adult↗
PubMed1993

[Stability of refraction 18 months after photorefractive keratectomy with excimer laser].

One-hundred-fourty-eight normal, sighted eyes, treated for myopia with argon fluoride 193-mm excimer laser, were analyzed 18 months postoperatively with respect to stability of refraction. Mean refraction 18 months after surgery was -0.32 D (+/- SD 0.89), a figure which was not significantly different from mean refractions at 12 and 15 months postoperatively. Also at 18 months, 86% of the eyes had an uncorrected visual acuity > or = 20/40, and 82% of the eyes were within 1.00 D of intended refraction (i.e. emmetropia). These percentages, which are directly related to postoperative refraction, are similar to those noted at 12 months after surgery. Although it may be too early to conclude that the 18-month refractions represent a definitive predictor of future refraction, the numerous similarities between the 12- and 18-months data presented in this study tend to suggest stability of refraction 18 months after excimer laser photorefractive keratectomy for myopia.

Adult↗
PubMed1992

Decreased serum bicarbonate as a manifestation of undernutrition secondary to nonorganic failure-to-thrive.

Eight of 101 children (8%) seen serially in consultation in an outpatient failure-to-thrive (FTT) clinic had isolated serum bicarbonate (TCO2) levels between 16 and 20 MEQ/dL (normal 22 to 30 MEQ/dL). None of these eight patients had signs or symptoms of renal disease, and all had nonorganic etiologic factors associated with their malnutrition. At the time of this review, follow-up TCO2 measurements were available for seven of the eight children who had attained normal weight (wt/age greater than fifth percentile on National Center for Health Statistics (NCHS) growth chart). All these children had normal TCO2 levels and no evidence of renal disease on follow-up more than 12 months later. Clinicians treating undernourished children who have low TCO2 measurements and have no signs or symptoms of renal disease and identified nonorganic factors, should consider a trial of therapies directed at nonorganic factors. Clinicians should be aware that a high percentage of undernourished children without other medical disease may have abnormal TCO2 measurements that correct after the institution of adequate caloric intake.

Acidosis, Renal Tubular↗
PubMed1991

The effect of a multidisciplinary team approach on weight gain in nonorganic failure-to-thrive children.

Failure-to-thrive (FTT) is a chronic symptom accounting for 1% of all patients admitted to pediatric hospitals. FTT, which is traditionally attributed to organic (OFTT) and/or nonorganic (NFTT) causes, results in undernutrition. Undernutrition has potentially serious effects on child development, behavior, and cognitive skills. We undertook a study of children with FTT to determine whether multidisciplinary team treatment resulted in improved weight gain compared with children treated in a primary care setting. Fifty-three children with NFTT referred to our outpatient FTT consultative clinic and 107 children with NFTT identified as comparison subjects from our primary care clinic (PCC) were enrolled in the study. Growth outcomes over a 6-month follow-up were analyzed using growth quotient (GQ) analysis. Children followed in the multidisciplinary team clinic grew better (GQ = 1.75 +/- 0.39 SD) than did children in the PCC (GQ = 1.18 +/- 0.42 SD, p less than .001). The use of a multidisciplinary team offers special advantages in the rapid correction of undernutrition in children with NFTT.

Child, Preschool↗
PubMed1990

Pregnancy outcomes in women potentially exposed to solvent-contaminated drinking water in San Jose, California.

During 1980-1981, solvents leaked from an underground storage tank of a semiconductor firm in southern Santa Clara County, California, contaminating local drinking water. The contaminated well was closed in December 1981. An epidemiologic study conducted in 1983 confirmed statistically significant excesses of adverse pregnancy outcomes in an exposed community compared with an unexposed community, but could not establish a causal connection between the leak and the adverse outcomes. This study expanded the first study; adverse pregnancy outcomes occurring in 1980-1985 were studied in two communities exposed to the contaminated drinking water and in two demographically comparable but unexposed communities. The period 1980-1981 was the time period in which the well was considered to have been contaminated and 1982-1985 was considered the postcontamination time period. Both exposed and unexposed communities were considered unexposed during the latter period (1982-1985). Out of 10,055 households surveyed, interviews were conducted with 1,105 women who reported one or more eligible pregnancies. Miscarriages and birth defects were validated by medical record review or physician reports. Although the authors again observed statistically significant excesses of spontaneous abortions and birth defects in the originally studied exposed area in 1980-1981, they observed deficits of these outcomes in the second exposed study area. Adjustment for potential confounders did not alter these findings. Analyses of pregnancy outcomes during 1981 in relation to exposure estimates based on hydrogeologic modeling of water and contaminant distribution within the exposed areas also indicated that the leak was not likely to have caused the observed excesses of adverse pregnancy outcomes in the originally studied area.

Abnormalities, Drug-Induced↗
PubMed1990

[Contact lenses for correction of refractive errors. A status determination].

The contact lens is still the most frequently used visual aid applied directly to the eye to correct refractive errors. The most important refractive indications and the advantages and drawbacks of the major lens types are discussed. Toric, bifocal and disposable lenses are also presented. The development of new, highly gas-permeable rigid materials are considered.

Contact Lenses↗