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Biomedical subjects

D S Durrie

Publications and source records attributed to D S Durrie.

At least 19 recordsLinked to original sources
PubMed2001

Intraocular lens power calculations using corneal topography after photorefractive keratectomy.

PURPOSE: To report two patients (two eyes) with previous photorefractive keratectomy, who subsequently underwent cataract extraction years later. DESIGN: Case reports. METHODS: Corneal topography was used to determine corneal power used in intraocular lens power calculations. RESULTS: In two eyes of two patients, intraocular lens calculations after photorefractive keratectomy were inadequate, which resulted in a hyperopic postoperative refractive error requiring implantation of a piggyback intraocular lens. CONCLUSION: Corneal topography to determine corneal power in patients with previous photorefractive keratectomy may result in unpredictable intraocular lens power calculations. The clinical history method is the standard to determine corneal power and should be considered in intraocular lens calculations before cataract surgery. We recommend supplying refractive patients with preoperative data for use in future formulas for intraocular lens selection.

Cornea↗
PubMed2001

Two-year outcomes of intrastromal corneal ring segments for the correction of myopia.

OBJECTIVE: To evaluate the safety and efficacy of Intrastromal Corneal Ring Segments (ICRS) for the correction of myopia. DESIGN: Nonrandomized, comparative trial. PARTICIPANTS: Patients enrolled in the United States Food and Drug Administration phase II and phase III clinical trials of the ICRS had best spectacle-corrected visual acuity (BSCVA) of 20/20 or better, myopia of -1.00 to -3.50 diopters (D), and a cylindrical correction of 1.00 D or less as measured by manifest refraction. INTERVENTION: Surgical correction of myopia with an ICRS. MAIN OUTCOME MEASURES: Efficacy was assessed by predictability of refractive outcome (deviation from predicted cycloplegic refraction spherical equivalent), stability of refractive effect, and postoperative uncorrected visual acuity. Safety was assessed by adverse events, maintenance or loss of preoperative BSCVA, and induced manifest refraction cylinder. RESULTS: Four hundred fifty-two patients were enrolled at 11 investigational sites in both studies. Of the 454 surgical attempts, 449 received an ICRS in one eye (0.25, 0.30, and 0.35 mm in 148, 151, and 150 eyes, respectively). First surgeries were attempted in 452 patients. An ICRS was successfully implanted in 447 initial eyes, and 5 surgeries were discontinued. Of the five discontinued surgeries, three patients subsequently exited from the study, and two patients went on to have the ICRS implanted in the second eye, bringing the total number of successful implants to 449 patient eyes. Month 24 postoperative follow-up was completed on 358 patients (80%). At month 24, 328 of 354 eyes (93%) were within +/-1.00 D of predicted refractive outcome. Refraction changed by 1 D or less in 97% of eyes (421/435) between 3 and 6 months after implantation and in 99% (343/348) between months 18 and 24. Before surgery, 87% of eyes (390/448) saw worse than 20/40 uncorrected; 24 months after surgery, 55% of eyes (196/358) saw 20/16 or better, 76% (271/358) saw 20/20 or better, and 97% (346/358) saw 20/40 or better. Although two eyes (2/358; 0.5%) lost two or more lines of BSCVA at 24 months; visual acuity in both was 20/20 or better. Intraoperative complications included anterior corneal surface perforation (three eyes) and anterior chamber perforations (two eyes, one during an attempted exchange procedure); all healed spontaneously without suturing and without loss of BSCVA. The ICRS was repositioned in five eyes to increase correction. Postoperative complications in one eye each were infectious keratitis, shallow segment placement, and loss of two lines of BSCVA at two or more consecutive examinations (subsequently regained). CONCLUSIONS: The ICRS safely, predictably, and effectively reduced or eliminated myopia of -1.00 to -3.50 D. The refractive effect was stable over time.

Adult↗
PubMed2000

LASIK enhancements.

As the field of refractive surgery continues to evolve, an increasing number of surgical options are available for LASIK enhancements. Nonetheless, older methods such as AK continue to play an important role in enhancement procedures. Improvements in instruments and techniques allow for previously made LASIK flaps to be safely lifted for additional myopic or hyperopic ablations. Newer methods such as Intacs placement provide an effective option for patients who are not good candidates for further ablative procedures. These advancements allow refractive surgeons to treat a wider range of myopia, hyperopia, and astigmatism effectively in eyes with a history of LASIK surgery.

Cornea↗
PubMed1999

Improvement of visual function with glare testing after photorefractive keratectomy and radial keratotomy.

PURPOSE: To evaluate the effect of a glare source on visual function in patients after photorefractive keratectomy and radial keratotomy. METHODS: Thirteen patients (22 eyes) who underwent photorefractive keratectomy and 20 patients (40 eyes) who underwent radial keratotomy were evaluated in this cross-sectional study. LogMAR visual acuity and contrast sensitivity were measured. Pupils were measured with the Rosenbaum card. A halogen/tungsten glare source approximated the luminance of headlights of an oncoming car at 100 feet. RESULTS: In the photorefractive keratectomy and radial keratotomy groups, pupils were significantly smaller (P<.01) and the pupillary clearance of the ablation zone in photorefractive keratectomy and the clear zone in radial keratotomy were significantly larger under the glare condition (P<.01). In the photorefractive keratectomy group, visual acuity and contrast sensitivity under the glare condition were significantly higher than in the no-glare condition (P = .02). In the radial keratotomy group, contrast sensitivity under the glare condition was significantly higher than under the no-glare condition (P = .001 to .003). CONCLUSIONS: After photorefractive keratectomy or radial keratotomy, the traditional glare source constricted the pupil and partially masked the optical aberrations, which resulted in an improvement in visual function. A "pupil-sparing" aberration test is needed for evaluation of visual function after refractive surgery.

Adult↗
PubMed1999

Phototherapeutic keratectomy for recurrent erosion syndrome in anterior basement membrane dystrophy.

PURPOSE: To determine the outcome of patients who received phototherapeutic keratectomy (PTK) for recurrent erosion syndrome due to anterior basement membrane dystrophy (ABMD). DESIGN: A retrospective, noncomparative case series. PARTICIPANTS: Forty-eight eyes of 43 consecutive patients who underwent PTK for recurrent erosions occurring in ABMD at the Hunkeler Eye Center from 1991 to April 1995. All patients had previously failed at least one method of medical or surgical treatment for recurrent erosions and had slit-lamp findings of ABMD on initial evaluation. INTERVENTION: The eyes each underwent manual superficial keratectomy and PTK with the Summit Omnimed excimer laser. MAIN OUTCOME MEASURES: Data were analyzed by a retrospective chart review for 1, 3, 6, and 12 months for the 36 eyes with at least 12 months of follow-up data available. They were analyzed for preoperative and postoperative visual acuity, change in spherical equivalent, recurrence rate, and patient satisfaction. RESULTS: The preoperative mean visual acuity was not statistically significantly different at 1 month after PTK. Statistically significant improvement in mean visual acuity was present at 3, 6, and 12 months. Recurrence of symptoms of recurrent erosion was present in 5 (13.8%) of 36 eyes during the 12-month follow-up period, which was managed with repeat PTK over the area of the cornea initially treated with PTK; 1 of 5 required a third PTK treatment. All recurrences presented within 6 months of PTK or repeat PTK. The mean dioptric change in spherical equivalent was not statistically significant. Patient satisfaction levels after PTK for recurrent erosions in ABMD were assessed in 21 (58%) of 36 patients on a scale of 0 to 5 (5 = most satisfied); the mean response was 4.14 of 5. CONCLUSIONS: Phototherapeutic keratectomy is an effective treatment for recurrent erosions occurring in the setting of ABMD, is well tolerated, and may improve visual acuity. The rate of recurrence of erosions in ABMD treated with PTK is low during a 12-month follow-up period.

Anterior Chamber↗
PubMed1999

Role of clearance and treatment zones in contrast sensitivity: significance in refractive surgery.

PURPOSE: To evaluate the relationship between contrast sensitivity, surgical treatment zone, and clearance (ablation or clear zone-pupil diameter) in photorefractive keratectomy (PRK) and radial keratotomy (RK). SETTING: Saint Louis University Eye Institute, St. Louis, Missouri, and Hunkeler Eye Center, Kansas City, Missouri, USA. METHODS: Thirteen patients had PRK and 20, RK. Contrast sensitivity was measured with the Stereo Optical F.A.C.T. (F.A.C.T.) and VectorVision CSV-1000 (VV) charts. Pupils were measured with the Rosenbaum card. RESULTS: In the PRK group, VV contrast sensitivity at 6 and 12 cycles per degree (cpd) correlated with the ablation zone (r2 = 0.18 and 0.22, respectively), while visual acuity and F.A.C.T. contrast sensitivity did not correlate. In the RK group, both VV and F.A.C.T. contrast sensitivity at 6 cpd correlated with clearance (r2 = 0.29 and 0.12, respectively). Pupils were larger with the VV test than with the F.A.C.T. chart because ambient chart luminance was less in the former. CONCLUSION: Contrast sensitivity is likely a more sensitive indicator of visual function than acuity in refractive surgery. The VV system unmasks aberrations from the transition zone of ablated and unablated cornea in PRK. Larger samples are needed to determine the critical ablation clearance of the pupil to avoid loss of visual function.

Adult↗
PubMed1999

One-year results from the phase III investigation of the KeraVision Intacs.

BACKGROUND: Limitations of the surgical correction for myopia include inaccuracy, instability, treatment of the central optical zone, and lack of reversibility. KeraVision Intacs offer an alternative that addresses these shortcomings. METHODS: We present 1 year of follow-up information on 95 subjects enrolled in the United States Food and Drug Administration Phase III clinical trials. RESULTS: At 1 year, 99% of patients (89 of 90) had 20/40 uncorrected vision or better. Ninety-two percent of eyes (83 of 90) were within 1.00 D of intended correction and 76% of eyes (68 of 90) were within 0.50 D of intended correction. Stability was achieved at 3 months, with 96% of subjects (86 of 90) having less than 1.00 D of change from their previous examination. In a substudy, 89% eyes (58 of 65) varied within +/- 0.50 D over the course of a day. Corneal curvature changed as predicted, resulting in a prolate aspheric shape within the central optical zone. Most complications or adverse events experienced were managed with additional medication or surgical intervention, resulting in a favorable outcome for subjects. CONCLUSIONS: KeraVision Intacs are effective, predictable, stable, and safe. This additive technique may also offer reversibility.

Adult↗
PubMed1998

Photorefractive keratectomy versus laser in situ keratomileusis for moderate to high myopia. A randomized prospective study.

OBJECTIVE: This report presents the results of a randomized clinical trial of photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK). DESIGN: A randomized, prospective multicenter clinical trial. PARTICIPANTS: A total of 220 eyes of 220 patients entered the study cohort: 105 randomized to PRK and 115 to LASIK. The mean preoperative manifest refraction spherical equivalent was -9.23 diopters (D) in the PRK group and -9.30 D in the LASIK group. INTERVENTION: All patients received a one-pass, multizone excimer laser ablation as part of either a PRK or LASIK procedure using the Summit Apex excimer laser. Attempted corrections ranged from 6.00 to 15.00 D. MAIN OUTCOME MEASURES: Data on uncorrected and spectacle-corrected visual acuity, predictability,and stability of refraction, corneal haze, and flap complications were analyzed. Patients were observed for up to 6 months. RESULTS: One day after surgery, 0 (0.0%) and 3 (4.5%) eyes in the PRK group saw 20/20 and 20/40 or better uncorrected, respectively, while 7 (10%) and 48 (68.6%) eyes in the LASIK group saw 20/20 and 20/40 or better, respectively. At 6 months after PRK, 13 (19.1%) and 45 (66.2%) eyes saw 20/20 and 20/40 or better, respectively, while after LASIK, 16 (26.2%) and 34 (55.7%) eyes saw 20/20 and 20/40 or better, respectively (odds ratio = 0.56 for likelihood of uncorrected visual acuity < 20/40 for PRK vs. LASIK, 95% confidence interval [CI] = 0.31-1.19). After PRK, 39 eyes (57.4%) were within 1.0 D of attempted correction compared with 24 eyes (40.7%) in the LASIK group (odds ratio = 0.50 for likelihood fo undercorrection 1.0 D for PRK vs. LASIK, 95% CI = 0.24-1.04); however, the standard deviation of the predictability was similar between groups: 1.01 D for PRK and 1.22 D for LASIK. From months 1 to 6, there was an average regression of 0.89 D in the PRK group and 0.55 D in the LASIK group. After PRK, eight eyes (11.8%) had a decrease in spectacle-corrected visual acuity of two Snellen lines or more; after LASIK, two eyes (3.2%) had a decrease of two lines or more (odds ratio = 3.89 for risk of loss of spectacle-corrected visual acuity for PRK vs. LASIK, 95% CI = 0.71-21.30). Only two eyes had postoperative spectacle-corrected visual acuity less than 20/32, however. CONCLUSIONS: Although improvement in uncorrected visual acuity is more rapid in LASIK than in PRK, efficacy outcomes in the longer term generally are similar between the two procedures. There is a greater tendency toward undercorrection in LASIK eyes using the specific laser and nomogram in this study, but the scatter in achieved versus attempted correction is similar, suggesting little difference in the accuracy of the two procedures. A suggestion of decreased propensity for loss of spectacle-corrected visual acuity in LASIK eyes requires further investigation.

Adult↗
PubMed1997

The intrastromal corneal ring segments. Phase II results for the correction of myopia.

OBJECTIVE: The purpose of the study was to evaluate the safety and efficacy of the intrastromal corneal ring segments (ICRS) for the correction of myopia. DESIGN: A 2-year phase II clinical trial of ICRS was initiated in May 1995. The investigational plan specifies that 150 patients with sighted eyes, requiring myopic corrections from -1.00 to -6.00 diopters (D), will each receive ICRS in 1 eye. The patient population will be divided into approximately five patients per ICRS thickness (0.25, 0.30, 0.35, 0.40, and 0.45 mm) per site. Six investigational sites are participating in the trial. PARTICIPANTS: Fifty-nine men and 43 women requiring myopic corrections were enrolled at four U.S. investigational sites. These 102 patients each received the ICRS product in 1 eye. INTERVENTION: Correction of myopia. MAIN OUTCOME MEASURES: Efficacy of ICRS was assessed with respect to the trial endpoints of predictability of refractive effect, uncorrected visual acuity (UCVA), stability of UCVA, maintenance of best spectacle-corrected visual acuity and stability of refractive effect. RESULTS: As shown by the available month-3 data (99 patients; all device thicknesses), 95 (96%) of 99 patients had a UCVA of 20/40 or better. Ninety-eight (99%) of 99 patients were within 2 lines of their preoperative best spectacle-corrected visual acuity. The average change (with standard error) in cycloplegic refraction (spherical equivalent) achieved by ICRS thickness was -1.27 +/- 0.09 D (0.25 mm), -2.13 +/- 0.16 D (0.30 mm), -2.56 +/- 0.15 D (0.35 mm), -3.77 +/- 0.37 D (0.40 mm) and -4.16 +/- 0.24 D (0.45 mm). Seventy-seven percent (76/99) of the patients were within +/-1.00 D of their intended correction. When the ICRS was removed in two cases, both patients returned to within 0.75 D of their preoperative manifest refraction. CONCLUSIONS: The ICRS appears to be a viable and effective alternative for the treatment of myopia. Additionally, as indicated by the explant data, the ICRS's refractive effect may be reversible upon removal of the device.

Adult↗
PubMed1996

Hydrogel intracorneal lenses in aphakic eyes.

BACKGROUND: The theoretical benefits of synthetic keratophakia over conventional corneal lamellar procedures are the elimination of donor concerns and superior refractive predictability. Additionally, synthetic material can be inspected for optical quality and power, and it can be sterilized. Furthermore, visual recovery should be more rapid since epithelium is not removed from the central part of the cornea and the need for keratocyte repopulation is eliminated. OBJECTIVE: To present results on patients who received an intracorneal implant (Kerato-Gel, Allergan Medical Optics, Irvine, Calif) that was made from lidofilcon A, a glucose-permeable hydrogel with an equilibrium water content of 68%. METHODS: The intracorneal implants were implanted in 35 adult patients for correction of aphakia. Inclusion criteria excluded patients with aphakia who were candidates for intraocular lenses. RESULTS: A total of 19 patients were followed up through 2 years postoperatively. For 16 patients with 2-year postoperative refractive data, the average spherical equivalent was -0.63 +/- 2.07 diopters (D). At 2 years, 88% of patients were within +/- 3.00 D of plano and 50% were within +/- 1.00 D. the mean change in Snellen's line for corrected visual acuity was -3.25 lines at 2 years for all patients and -2.0 lines for a subgroup of five patients who were free of vision-limiting preoperative disease. CONCLUSIONS: Results suggest that this intracorneal implant is well tolerated by the cornea and can provide predictable refractive results in patients with high-risk aphakia. Limitations of the procedure are uneven microkeratome resections, loss of best-corrected visual acuity, and irregular astigmatism in some patients. Although these data show good evidence of biocompatibility of the implant material, technical surgical progress is needed to advance this procedure into clinical therapeutic practice.

Adult↗
PubMed1996

Late onset of corneal scar after excimer laser photorefractive keratectomy.

PURPOSE: We studied the occurrence of late scarring after photorefractive keratectomy and its response to topical corticosteroids and debridement during the course of follow-up of 950 eyes that had photorefractive keratectomy with excimer laser. METHODS: Five eyes of four patients developed localized corneal scars, decreased visual acuity, and increased myopia after five to 33 months of good visual acuity, with trace haze. In two eyes, scars were removed by debridement alone. In these two eyes, recurrent scars were treated by debridement, followed by aggressive treatment with topical corticosteroids. Two other eyes were treated with topical corticosteroids alone. The fifth eye, which developed a scar after debridement to correct a subjective visual distortion after photorefractive keratectomy, was treated with debridement followed by aggressive topical corticosteroids. RESULTS: Treatment with topical corticosteroids alone in two eyes improved uncorrected visual acuity slightly and decreased myopia, although the scars remained unchanged. Debridement without aggressive topical corticosteroid use resulted in rapid return of the scars and a decrease in visual acuity. Subsequent debridement after aggressive topical corticosteroid treatment resulted in resolution of scars and no recurrence after discontinuation of corticosteroids in one case. In another case, the scar recurred eight months after discontinuation of topical corticosteroids. In Case 4, the scar has not recurred as the topical corticosteroid dosage has been reduced. CONCLUSIONS: Patients who undergo photorefractive keratectomy should be counseled concerning the risk of late scarring, reexamined frequently after photorefractive keratectomy, and treated with topical corticosteroids after corneal trauma. Long-term treatment with topical corticosteroids may be required to prevent the recurrence of scars after debridement.

Adult↗
PubMed1995

Relation of visual symptoms to topographic ablation zone decentration after excimer laser photorefractive keratectomy.

BACKGROUND: The authors used computer-assisted videokeratoscopy to analyze the relation of photorefractive keratectomy ablation zone decentration to subjective patient assessments of disturbing visual symptoms. METHODS: Ablation zone decentration was measured 1 month postoperatively. The study population was divided into two groups: group 1, patients whose ablation zone decentrations were less than 0.50 mm; group 2, patients whose ablation zone decentrations were greater than 0.50 mm. Visual symptoms including glare, rings or halos around lights and problems with night driving were scored preoperatively and 6 months postoperatively. The Hotelling T-square and chi-square tests were used. RESULTS: The mean decentration from the center of the ablation zone to the pupillary center was 0.30 mm and 190 degrees for group 1 compared with 0.66 mm and 198 degrees for group 2. The Hotelling T-square test showed a significant statistical preoperative/postoperative difference in group 1 (P < 0.03) for the halo symptom category. No other symptom category showed a significant statistical difference in either group for the mean scores. The Hotelling T-square test did not show a statistically significant difference between the two groups preoperatively to postoperatively regarding the mean scores of the individual patient differences for the three symptoms. The only significant statistical difference for the individual patient ratings preoperatively to postoperatively was for the halo symptom category (chi-square = 7.756; P < 0.03). CONCLUSIONS: Multivariate analysis did not show a significant statistical difference preoperatively between the two groups or postoperatively except for group 1 with regard to the halo symptom category. It appears from this study that ablation zone decentrations less than 0.89 mm from the pupillary center do not necessarily produce unwanted visual symptoms 6 months postoperatively.

Cornea↗
PubMed1994

Phacoemulsification with intraocular lens implantation after excimer photorefractive keratectomy: a case report.

We report the first case, to our knowledge, of phacoemulsification with lens implantation in a patient with previous photorefractive keratectomy for myopia. Intraocular lens calculations were performed using manual and automated keratometry. The surgical and postoperative course were uneventful with a good visual outcome. Standard intraocular lens calculation and surgical technique appear to be successful for cataract extraction after photorefractive keratectomy.

Cataract Extraction↗
PubMed1994

Electron microscopic findings in a cornea with recurrence of herpes simplex keratitis after excimer laser phototherapeutic keratectomy.

Excimer laser phototherapeutic keratectomy is emerging as an alternative therapy to corneal transplantation for the treatment of multiple corneal diseases. We report three cases of recurrence of herpes simplex keratitis after treatment of herpetic corneal scars with the excimer laser. In two cases, the patients underwent subsequent corneal transplantation. One corneal button examined with transmission electron microscopy (TEM) demonstrated a well-differentiated epithelium over the area of ablation, a linear, continuous basal lamina, and no viral particles. Anterior stromal scarring may have resulted from the laser treatment itself or may represent incomplete ablation of previous scars. Whether reactivation of the virus was stimulated by the laser or occurred as part of the natural history of the disease is uncertain. We recommend that patients who undergo excimer laser treatment for herpes simplex scarring receive careful follow-up including antiviral coverage.

Adult↗
PubMed1993

Topographical analysis of the centration of excimer laser photorefractive keratectomy.

A major advantage of myopic photorefractive keratectomy (PRK) is the precision with which the excimer laser ablates corneal tissue. But like other refractive surgery procedures, PRK must solve the problem of accurately centering the treatment zone. We present our technique for PRK centration with postoperative corneal topographic data on 110 patients from Phase IIB and III of the clinical trials. The distance between the center of the post-PRK flat zone and the corneal vertex was determined by topography in millimeters and meridian degrees. On average, treatment zones were decentered down and right 0.52 mm at 196.74 degrees; 92.73% were centered within 1.00 mm, while 57.27% were within 0.50 mm. The centration data were correlated to postoperative visual acuity as well as treatment zone diameter. Mean uncorrected visual acuity was 20/20 for decentrations up to 1.00 mm but fell to 20/30 for deviations greater than 1.00 mm. Best corrected acuity was also preserved below 1.00 mm but compromised above this level. No difference in decentration was found between 4.5 mm and 5.0 mm ablation zones. Our findings indicate that PRK centration is accurate within 1.0 mm in over 92% of cases and that visual acuity is relatively preserved despite deviations from perfect centration. Further technical improvements will enhance the accuracy of PRK.

Adult↗
PubMed1993

Centration of excimer laser photorefractive keratectomy relative to the pupil.

The centration of excimer laser photorefractive keratectomy (PRK) is critical to the procedure's success. We evaluated PRK centration in 49 patients using the EyeSys topography system. Ablation zone centration was measured from the corneal vertex and from the pupillary center using the pupil-finding software. Centration was measured more accurately from the pupillary center (0.40 mm) than from the corneal vertex (0.44 mm). Right eyes were decentered less than left eyes. There was an unpredictable correlation between amount of decentration and postoperative visual acuities. The ability to measure centration of keratorefractive procedures precisely from the pupil is an important advance in topography technology.

Cornea↗