Biomedical subjects

D R Sanders

Publications and source records attributed to D R Sanders.

At least 19 recordsLinked to original sources

PubMed1998

Implantable contact lens for moderate to high myopia: phase 1 FDA clinical study with 6 month follow-up.

PURPOSE: To assess the short-term safety and efficacy of the implantable contact lens (ICL) to treat moderate to high myopia. SETTING: Phase 1 U.S. Food and Drug Administration clinical study of the ICL conducted at four sites in the United States. METHODS: Ten patients with myopia of 7.00 diopters (D) or greater had implantation of a Staar Surgical ICL and were examined preoperatively (baseline) and 1 day, 1 week, and 1, 3, and 6 months postoperatively. Mean preoperative myopia was 7.75 D (range 7.25 to 9.37 D). RESULTS: Six months postoperatively, 5 of 10 eyes (50%) had an uncorrected visual acuity (UCVA) of 20/20 or better, and all eyes had a UCVA of 20/30 or better. All eyes had a best spectacle-corrected visual acuity (BSCVA) of 20/20 or better and 6 eyes (60%), of 20/15 or better. Six eyes (60%) had an improvement of one or more lines of BSCVA. Mean postoperative spherical equivalent was -0.025 D +/- 0.47 (SD). Eight eyes (80%) were within +/- 0.250 D of emmetropia, and all were within +/- 1.125 D. No intraoperative or postoperative complications or adverse reactions were observed. CONCLUSIONS: The results support the short-term safety, efficacy, and predictability of ICL implantation to treat moderate to high myopia.

Adult↗

PubMed1995

Clinical evaluation of hexagonal keratotomy for the treatment of primary hyperopia.

We evaluated the effectiveness of spiral hexagonal keratotomy in correcting primary hyperopia in 199 eyes. One hundred eighty-four eyes (92.5%) had a minimum follow-up of three months. Mean follow-up was 11.9 months and maximum, 36.2 months. Secondary astigmatic keratotomy was performed on 54 eyes six to eight months after initial hexagonal surgery to correct induced astigmatism. The mean reduction in spherical equivalent was -1.6 +/- 0.9 diopters (D) (range -5.6 to +0.9 D). The mean increase in refractive cylinder was +0.5 +/- 0.9 D (range -2.3 to +3.0 D). Uncorrected acuity improved by +3.2 lines, while best corrected acuity decreased slightly by -0.26 lines. Loss of two or more lines of best corrected acuity that was attributable to surgery was between 0.5% and 4.0%.

Adult↗

PubMed1994

Long-term (5- to 12-year) follow-up of metal-blade radial keratotomy procedures.

OBJECTIVE: To evaluate the long-term stability of the refractive outcome after metal-blade radial keratotomy procedures. DESIGN: A cohort of 146 patients who underwent 225 consecutive metal-blade radial keratotomy procedures that were performed under a uniform protocol between November 1979 and August 1981 was monitored prospectively, with 64% of the patients followed up for at least 5 years. MAIN OUTCOME MEASURES: Changes in spherical equivalent and changes in average keratometry were evaluated within the following periods: 3 months to 1 year; 1 to 2 years; 2 to between 3 and 4 years (mean, 3.7 years); between 3 and 4 (mean, 3.7 years) to between 5 and 12 years (mean, 8.5 years); and 1 to between 5 and 12 years (mean, 8.5 years). RESULTS: Total mean change in refraction between 1 year and the average of 8.5 years of follow-up was 1.01 diopters (D) (SD, 1.13 D). At 1 year, 31% of the cases were at least 1 D hyperopic, whereas at an average of 8.5 years, 48% were at least 1 D hyperopic. Fifty-four percent of the cases had shifted in the hyperopic direction by 1 D or more. Stepwise regression analysis failed to identify significant predictive factors for the hyperopic shifts. CONCLUSIONS: The trend toward progressive hyperopic shifts within this cohort has continued with time. Other long-term studies have documented similar, although somewhat smaller, hyperopic shifts among both patients treated with metal-blade and patients treated with diamond-blade procedures. Causative factors for the hyperopic shift have not been identified. It remains to be seen if eyes undergoing current, more cautious surgical approaches to radial keratotomy will also experience this phenomenon.

Follow-Up Studies↗

PubMed1994

Changing practice patterns in refractive surgery: results of a survey of the American Society of Cataract and Refractive Surgery.

A questionnaire on refractive surgical practice was sent to the entire membership of the American Society of Cataract and Refractive Surgery in 1992. One thousand eight hundred and forty-one (1,841) of the 4,950 members returned the survey for a response rate of 37.2%. The questionnaire was designed to be self-administered and elicited information on types of refractive procedures performed in the survey year and the preceding year, as well as the intent to perform refractive procedures in the future. Surgeons who perform radial keratotomy (RK) increased from 22% in 1991 to 30% in 1992; 45% expected to perform RK in 1993-1994. The following categories of information were requested: characteristics of RK patients, techniques used by the surgeon, characteristics of the surgeon's overall practice, type of RK training, surgical outcome, and prevalence of complications. The results of this survey indicate that the use of RK and astigmatic keratotomy (AK), as well as other refractive procedures, is steadily increasing. Radial keratotomy was mainly performed on patients 20 to 49 years of age who had low to moderate myopia. The majority of surgeons used four to eight radials, centrally directed incisions, and single depth settings. Three quarters of the surveyed RK surgeons used the Casebeer nomogram. The survey results indicated that 42% of surgeons performing photorefractive keratectomy (PRK) did not perform RK or other refractive procedures, suggesting that growth in the practice of PRK following FDA approval may come from both current RK surgeons and novice refractive surgeons.

Adult↗

PubMed1994

Small incision surgery with the STAAR Elastimide three-piece posterior chamber intraocular lens.

One hundred twelve patients scheduled for uncomplicated cataract removal were randomly assigned to receive a STAAR Elastimide three-piece foldable intraocular lens inserted through a 4.0 mm incision or a STAAR poly(methyl methacrylate) (PMMA) lens inserted through a 7.0 mm incision. The same surgeon performed all surgeries using identical techniques, except for incision size and number of sutures. Patients receiving Elastimide lenses had significantly better uncorrected visual acuity postoperatively than patients receiving PMMA lenses and also had significantly less keratometric cylinder, surgically induced cylinder (vector method), and refractive cylinder. The Elastimide foldable lens offers the advantages of small incision surgery for patients who require a three-piece lens.

Aged↗

PubMed1993

When keratometric measurements do not accurately reflect corneal topography.

The keratometer has been the standard for measuring corneal curvature for decades and until recently seemed sufficient for most clinical situations. However, it measures only four points from a small region of the cornea and assumes that the cornea is symmetrical. We document with a number of examples a variety of clinical cases in which keratometry provides either incomplete or frankly misleading information. We believe that corneal topography is now an invaluable clinical tool and will replace the keratometer in standard clinical practice.

Astigmatism↗

PubMed1993

Effect of cataract wound incision size on acute changes in corneal topography.

A randomized prospective trial compared keratometric and visual outcomes for 196 patients receiving 3.2 mm, 5.0 mm, or 6.0 mm incisions for cataract removal and intraocular lens implantation. There were no statistically significant differences among the groups preoperatively or at one to two days or three to six months postoperatively in mean keratometric cylinder, no differences postoperatively in surgically induced cylinder, and no differences in best-corrected visual acuity. Significantly more (P < .01) 3.2 mm cases (75%) had uncorrected visual acuity of 20/40 or better at one to two days postoperatively than 5.0 mm (50%) or 6.0 mm cases (47%). Computer-assisted corneal topographic images were available for the last 56 patients enrolled. Patients receiving 3.2 mm incisions had significantly less wound-related flattening than other patients (P < .05) and tended to have fewer surgically induced changes in corneal shape overall. Changes identified by corneal topography were inconsistent with keratometrically assessed cylinder in 14 patients.

Acute Disease↗

PubMed1992

Effect of posterior chamber intraocular lens design and surgical placement on postoperative outcome.

Intraocular lens (IOL) design, optical configuration, and placement have potential effects on postoperative outcome. Laboratory studies have suggested that one-piece, biconvex designs may reduce or delay posterior capsular opacification and that in-the-bag fixation of the posterior chamber IOL may reduce inflammation. To document the clinical significance of IOL design and placement, we conducted a randomized, prospective, clinical trial. Six hundred uncomplicated capsulorhexis and phacoemulsification patients were randomized in a three-factor design to receive an IOL that was one-piece or three-piece, had a biconvex, plano-convex, or laser ridge optic, and was bag-or sulcus-fixated. Treatment differences were related to lens placement. Patients with bag-fixated IOLs had less posterior capsular opacification, fewer YAG laser capsulotomies, a higher percentage of centered lenses, less inflammation, and fewer late posterior capsular striae than those with sulcus-fixated IOLs. In the latter group, patients with three-piece IOLs had fewer posterior capsular striae at three months postoperatively. All six occurrences of haptic loop distortion were in patients with three-piece IOLs. Patients with the one-piece design had less late inflammation than those with the three-piece design. Fewer YAG capsulotomies were necessary at one year in patients with the biconvex design than in those with the plano-convex or laser ridge configurations. Operative complications, endothelial cell loss, and postoperative complications were not IOL-related.

Adult↗

PubMed1992

Effect of small incision intraocular lens surgery on postoperative inflammation and astigmatism. A study of the AMO SI-18NB small incision lens.

A single center, single surgeon, randomized, prospective clinical trial was performed comparing the effectiveness of small (3.5 mm to 4.0 mm) incision intraocular lens surgery and a larger (6.0 mm) incision in improving uncorrected visual acuity and reducing post-operative inflammation and surgically induced astigmatism. One hundred twelve eligible unilateral cases were randomized to receive a 3.5 mm to 4.0 mm incision with implantation of an Allergan Medical Optics three-piece SI-18NB silicone lens (56 cases) or a 6.0 mm incision with implantation of a three-piece biconvex poly(methyl methacrylate) lens (56 cases). At one day after surgery, significantly (P less than .01) more patients with 3.5 mm incisions had 20/40 or better uncorrected visual acuity than patients with 6.0 mm incisions (45% vs 20%). Forty percent of patients with 6.0 mm incisions vs 14% of patients with 3.5 mm incisions had visual acuities of 20/100 or worse. At one day after surgery, the larger incision group had significantly higher (P less than .01) mean keratometric cylinder (2.28 diopters vs 1.28 diopters in the small incision group). The two groups were comparable by three months. Laser flare/cell meter measurements were taken for each group but showed no significant differences in mean flare or cell measurements between the groups.

Aged↗

PubMed1992

Visual, astigmatic, and inflammatory results with the Staar AA-4203 single-piece foldable IOL: a randomized, prospective study.

One hundred twelve unilateral cataract extraction patients were randomly assigned to receive either a one-piece Staar Model AA-4203 silicone intraocular lens (IOL) implanted through a 3.2-millimeter incision, or a one-piece polymethylmethacrylate IOL implanted through a 6.0-millimeter incision. Follow up was 96% at 1 day postoperatively, 90% at 3 months, and 70% at 1 year. Fifty-three percent of the eyes that received a smaller incision could see 20/40 or better uncorrected at 1 day, as compared with 19% of the eyes that received a 6-millimeter incision (P < .01). At 3 months, significantly more smaller-incision eyes could still see 20/40 or better (P = .03). The smaller-incision eyes also had significantly less surgically-induced astigmatism at both 1 day (P < .01) and 3 months (P = .02), and had significantly less flare (P < .01) and cellular reaction (P = .04) at 1 day.

Aged↗

PubMed1991

Visual and refractive results of multifocal intraocular lenses.

One hundred forty-nine selected patients with bilateral multifocal intraocular lenses (IOLs) were evaluated and compared retrospectively with 131 patients with bilateral monofocal IOLs. Seventy-eight percent of multifocal cases and 74.8% of monofocal cases had uncorrected visual acuity of 20/40 or better. Fifty-four percent of multifocal cases had near uncorrected visions of J1 to J3. Eighteen percent had best-corrected near vision of J4 or worse. Sixty-three percent of multifocal cases versus 4% of monofocal cases needed no spectacle correction. Multifocal cases reported significantly more visual side effects (flare, glare, and halos). The 10% of cases with poor satisfaction (rating vision as fair-to-poor) had significantly (P = 0.03) more postoperative astigmatism (1.1 prism diopters [D] versus 0.74 D) compared with satisfied (good-to-excellent) cases. Patients who were dissatisfied reported more need for corrective lenses but not more side effects. A greater decrease in contrast sensitivity at low contrast levels was detected among multifocal cases. Both groups had similar contrast sensitivity at 96% and 50% contrast, but at 11% contrast, multifocal cases averaged a loss of 3.45 Snellen lines (to 20/48.2) compared with 2.65 lines (to 20/36) for monofocal cases.

Consumer Behavior↗

PubMed1991

Effect of incision direction on radial keratotomy outcome.

The goal of maximizing radial keratotomy results by using optical-zone-directed (centrally directed) incisions rather than limbus-directed (peripherally directed) incisions is evaluated in this prospective study. Five patients had bilateral radial keratotomy, with optical-zone-directed incisions in one eye and limbus-directed incisions in the other. The order of surgery and eye was randomly assigned. Patients were evaluated preoperatively, at one week, and at one month. There were no significant differences preoperatively between the two groups of eyes in spherical equivalent or keratometry. At one week postoperatively, however, there were significant group differences in spherical equivalent changes (P less than .010). Eyes with limbus-directed incisions were -2.2 diopters (D) myopic, on average, while eyes with optical-zone-directed incisions were near emmetropic, with a mean spherical equivalent of 0.10 D. Because of these results, we stopped randomizing cases at this point. The difference in surgical effect was still significant at three months (P less than .01); eyes with limbus-directed incisions had an average of 3.5 D less surgical effect than eyes with optical-zone-directed incisions.

Adult↗

PubMed1991

Use of small incisions to control induced astigmatism and inflammation following cataract surgery.

A series of 55 small incision (3 mm) silicone-implanted cataract cases closed with horizontal sutures and a concurrent series of 48 6 mm to 7 mm incision poly(methyl methacrylate)-implanted cases closed with radial incisions were compared retrospectively for surgically induced astigmatism. At two to three weeks after surgery, the mean surgically induced astigmatism in the poly(methyl methacrylate) group was more than twice as high as in the silicone group (2.27 D vs 1.07 D, P less than .01). In addition, a series of 41 small incision cases and a concurrent series of 61 cases with 6 mm to 7 mm incisions were compared for inflammation as measured by an FC-1000 laser flare/cell meter. The larger incision cases had significantly higher average cell counts at one day and one week postoperatively (P = .005 and P = .03, respectively) and had significantly higher average flare measurement at one day (P = .01) than the smaller incision cases.

Aged↗

PubMed1990

Inhibition of blood-aqueous humor barrier breakdown with diclofenac. A fluorophotometric study.

Various doses of a new topical nonsteroidal anti-inflammatory agent, diclofenac sodium, were tested against prednisolone sodium phosphate in a randomized double-masked study to determine comparative efficacy and safety regarding the reduction of postsurgical ocular inflammation. Inflammation was assessed by measuring fluorescein leakage into the anterior chamber using fluorophotometry techniques. Increased leakage in each patient's operated-on eye compared with the unoperated-on control eye was attributed to a breakdown in the blood-aqueous barrier caused by the cataract surgery. Elimination or significant reduction of fluorescein leakage within a treatment group constituted increased efficacy in controlling inflammation. A total of 124 cases were analyzed. There were no preoperative differences among groups in fluorescein leakage. At 1 week after surgery, all three diclofenac groups had significantly less fluorescein leakage compared with the prednisolone group. Mean percent increases were 56% to 118% in diclofenac groups vs 324% in the prednisolone group. No differences among diclofenac concentrations were detected. The differences between prednisolone and diclofenac were also present, although of lesser magnitude, at 3 weeks. This demonstration of increased efficacy of the nonsteroidal anti-inflammatory agent vs prednisolone is promising given the known side effects of ocular steroids.

Aged↗

PubMed1990

Effect of sulcus vs capsular fixation on YAG-induced pressure rises following posterior capsulotomy.

Neodymium-YAG capsulotomy for secondary cataracts can induce acute intraocular pressure rises, possibly by a blocking of the trabecular meshwork by debris. To test a hypothesis that bag-fixated intraocular lenses may act as a barrier to debris, thus reducing pressure rises after YAG capsulotomy, we conducted a study comparing pressures (at 1, 2, 3, 6, and 24 hours after YAG capsulotomy) between bag-fixated and sulcus-fixated cases. There were substantial and statistically significant intraocular pressure rises in the sulcus-fixated group starting at 1 and 2 hours after YAG capsulotomy, and peaking at 3 hours (mean rise, 7.83 mm Hg). There were no such peaks of intraocular pressure rise among bag-fixated cases (mean change, -0.32 mm Hg at 3 hours). There was a weak but significant (r = -.18) correlation between the change 1 hour after YAG capsulotomy in intraocular pressure and percent of enclosure of the intraocular lens optic among bag-fixated cases. Higher proportions (fourfold to fivefold) of cases with sulcus-fixated lenses had significant flare and particulate matter in the anterior chamber, compared with bag-fixated cases.

Adolescent↗

PubMed1990

Astigmatic keratotomy to correct preexisting astigmatism in cataract patients.

We evaluated three general strategies for dealing with astigmatism control following phacoemulsification with posterior chamber intraocular lens surgery: (1) a neutral wound closure to minimize surgically induced cylinder; (2) wound revision techniques to minimize residual postoperative cylinder; (3) astigmatic keratotomy incisions to treat preexisting astigmatism. With the neutral wound closure, mean postoperative keratometric cylinder averaged less than 1 diopter (D). In the presence of moderate preoperative astigmatism (1.0 D to 1.9 D), the wound revision technique tended to undercorrect, while the astigmatic keratotomy tended to overcorrect. However, the keratotomy procedure resulted in less postoperative cylinder. For cases with substantial preoperative astigmatism (greater than or equal to 2 D), the astigmatic keratotomy groups corrected more of the preoperative cylinder, which resulted in a greater proportion of cases with less than 1 D of postoperative cylinder and a smaller proportion with more than 2 D. Results suggest that astigmatic keratotomy is a useful adjunct to correct preexisting astigmatism in cataract patients. However, this procedure as any incisional refractive surgery technique has a certain amount of inherent biological variability.

Adult↗

PubMed1990

Development of the SRK/T intraocular lens implant power calculation formula.

A new implant power calculation formula (SRK/T) was developed using the nonlinear terms of the theoretical formulas as its foundation but empirical regression methodology for optimization. Postoperative anterior chamber depth prediction, retinal thickness axial length correction, and corneal refractive index were systematically and interactively optimized using an iterative process on five data sets consisting of 1,677 posterior chamber lens cases. The new SRK/T formula performed slightly better than the Holladay, SRK II, Binkhorst, and Hoffer formulas, which was the expected result as any formula performs superiorly with the data from which it was derived. Comparative accuracy of this formula upon independent data sets is addressed in a follow-up report. The formula derived provides a primarily theoretical approach under the SRK umbrella of formulas and has the added advantage of being calculable using either SRK A-constants that have been empirically derived over the last nine years or using anterior chamber depth estimates.

Anterior Chamber↗

PubMed1990

Comparison of the SRK/T formula and other theoretical and regression formulas.

We compared the predictive accuracy of the SRK/T formula to the SRK II, Binkhorst II, Hoffer, and Holladay formulas in seven series of cases totaling 1,050 eyes. In the combined group, the SRK/T and Holladay formulas performed only slightly better than the other formulas. In short eyes (less than 22 mm), all formulas performed well, with the SRK/T, SRK II, and Holladay formulas performing marginally better. In moderately long eyes (greater than 24.5 mm, less than or equal to 27 mm), the Hoffer and Binkhorst II formulas had a greater proportion of cases with greater than 2 diopters (D) of error and the SRK/T and Holladay were again marginally better. In the very long eyes (greater than 27 mm and less than or equal to 28.4 mm), there were only 11 cases and all formulas performed well since none had greater than 2 D of prediction error. In an extremely long eye data set (greater than 28.4 mm), the SRK II formula clearly gave the poorest result. Eyes of this length occurred in only 0.1% of cases in our unselected series. Results support the contention that the present second and third generation IOL power formulas give fairly equivalent accuracy. Other factors, such as availability, ease of use, and ability to tailor or individualize, become major considerations.

Eye↗