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G O Waring

Publications and source records attributed to G O Waring.

At least 19 recordsLinked to original sources
PubMed2001

Effects of laser in situ keratomileusis (LASIK) on the corneal endothelium 3 years postoperatively.

PURPOSE: To investigate the effects of laser in situ keratomileusis (LASIK) on the corneal endothelium 3 years postoperatively. METHODS: Patients who were subjects of a previous prospective study (Am J Ophthalmol 125:465-471, (April) 1998) were contacted for a follow-up analysis of the central corneal endothelium. Noncontact specular microscopy was performed 35 to 37 months after LASIK on 52 eyes of 27 patients of the original cohort of 98 eyes of 65 patients and six eyes of three patients who were previously lost to follow-up after their initial post-LASIK evaluation. Patient age ranged from 29 to 66 years at the time of the original LASIK procedure. Attempted corrections ranged from 2.25 to 14.5 diopters of myopia, giving theoretical ablation depths of 182 to 332 microm below the corneal surface. Forty-eight eyes (83%) had a history of preoperative contact lens use (3 to 33 years). Central endothelial cell density, coefficient of variation of cell size, and percent of hexagonal cells were analyzed using 72 to 152 cells from each image. Multivariate analysis was used to search for factors that might predict changes in cell density, coefficient of variation, and percent of hexagonal cells. RESULTS: The mean +/- SD preoperative cell density was 2,498 +/- 354 cells per mm(2), the mean coefficient of variation was 0.36 +/- 0.07, and the percent of hexagonal cells was 58 +/- 6. Three years after surgery there was no statistically significant change in the mean endothelial cell density (2,489 +/- 335 cells per mm(2); P = 0.88, paired t test) or the percent of hexagonal cells (60 +/- 7; P = 0.14, paired t test). The mean coefficient of variation was significantly lower postoperatively (0.32 +/- 0.04; P = 0.0006, paired t test); a repeated measures analysis showed that this significant improvement could not be explained by cessation of contact lens wear after LASIK (P = 0.34). Multivariate analysis did not identify any factors that were predictive of change in cell density, coefficient of variation, and percent of hexagonal cells. CONCLUSIONS: Laser in situ keratomileusis for the correction of 2.25 to 14.5 diopters of myopia had no significant effect on central corneal endothelial cell density or the percent of hexagonal cells 3 years after surgery. The coefficient of variation of cell size improved significantly 3 years after surgery.

Adult↗
PubMed2001

Laser in situ keratomileusis for myopia up to -11 diopters with up to -5 diopters of astigmatism with the summit autonomous LADARVision excimer laser system.

OBJECTIVE: To assess the safety and effectiveness of the Summit Autonomous LADARVision active tracking narrow beam excimer laser system for laser in situ keratomileusis (LASIK) correction of myopia and astigmatism. DESIGN: A multicenter, prospective noncomparative case series. PARTICIPANTS: This cohort consisted of 177 eyes corrected for spherical myopia up to -11 diopters (D) and 170 eyes corrected for myopia up to -11 D spherical equivalent with astigmatism up to -5 D. INTERVENTION: Treatments were performed at four sites in the United States using a 6-mm optic zone for spherical myopes and a 5.5-mm optic zone with a 1-mm blend for astigmats. MAIN OUTCOME MEASURES: Visual acuity, subjective refraction, vector analysis, subject satisfaction, intraocular pressure, complications, and adverse reactions. RESULTS: Six-month follow-up was available on 157 spherical eyes and 113 astigmatic eyes. For spherical myopes, uncorrected visual acuity (UCVA) was 20/20 or better in 60.5%, 20/25 or better in 80.3%, and 20/40 or better in 93.9%. The mean spherical equivalent was -0.29 +/- 0.45 D with 75.2% +/- 0.50 D and 94.9% +/- 1.00 D of intended. A loss of two lines of best spectacle-corrected visual acuity (BSCVA) occurred in 0.6%, and no eyes lost greater than two lines of BSCVA. For astigmatic myopes, UCVA was 20/20 or better in 52.0%, 20/25 or better in 74.5%, and 20/40 or better in 94.1%. The mean spherical equivalent was -0.23 +/- 0.49 D with 75.2% +/- 0.50 D and 95.6% +/- 1.00 D of intended. A loss of two lines of BSCVA occurred in 0.9%, and no eyes lost greater than two lines of BSCVA. Vector analysis showed that 99% of the intended cylinder was corrected on average with a mean angle of error of 4.2 degrees. Refractive stability was achieved between 1 and 3 months in 97.5% of spherical eyes and 99.4% of astigmatic eyes and confirmed between 3 and 6 months in 100% of both spherical and astigmatic eyes. CONCLUSIONS: Eyes treated for myopia up to -11 D of spherical equivalent with or without astigmatism up to -5 D show early refractive stability, good UCVA outcomes, no significant loss of BSCVA, accurate correction of astigmatism, and slight undercorrection without a change from the photorefractive keratectomy algorithm and with a single treatment.

Adult↗
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↗
PubMed2001

Laser in situ keratomileusis: surgical technique.

Laser in-situ keratomileusis is an increasingly popular technique for the correction of refractive errors that was initially described by Pallikaris in 1990. It involves the excimer laser ablation of corneal stroma beneath a hinged corneal flap that is created with a microkeratome. The purpose of this chapter is to report the LASIK surgical technique that has evolved at the Emory Vision Correction Center since 1995 when an investigation study of this technique for the correction of myopia began.

Corneal Stroma↗
PubMed2000

Videokeratography after excimer laser in situ keratomileusis for myopia.

OBJECTIVE: The purpose of this study was to define qualitative patterns of videokeratography after excimer laser in situ keratomileusis (LASIK) for myopia and to identify associations of videokeratography patterns with clinical variables. DESIGN: Single-center, retrospective, cohort study. PARTICIPANTS: One hundred twenty-six eyes of 68 patients with myopia who desired surgical correction of myopia ranging from -1.50 to -8.80 diopters. INTERVENTION: Myopia was corrected with LASIK using a Summit OmniMed/Apex excimer laser. Computer-assisted videokeratography data were acquired at 3 months after primary LASIK, and associations of videokeratography pattern with clinical variable were assessed. MAIN OUTCOME MEASURES: Seven subgroup ablation zone patterns were characterized using tangential curvature maps; these subgroups were combined into pooled symmetric and asymmetric groups. Associations with age, attempted correction, single-zone or multizone ablation, postoperative uncorrected and spectacle-corrected visual acuity, predictability, astigmatism, corneal uniformity, glare disability, and contrast sensitivity were analyzed. RESULTS: Thirty-two eyes (25.4%) showed a uniform pattern, 14 eyes (11.1%) showed a bow-tie pattern, 22 eyes (17.5%) showed a peninsula pattern, 22 eyes (17.5%) showed a semicircular pattern, 22 eyes (17.5%) showed an off-center blue spot pattern, 10 eyes (7.9%) showed an irregular pattern, and 4 eyes (3.2%) showed a central island pattern. Spectacle-corrected visual acuity, astigmatism, corneal uniformity, glare disability, and contrast sensitivity were significantly related to videokeratography pattern, although the difference among videokeratography groups was clinically small. Age, attempted correction, single- or multizone ablation, and postoperative uncorrected visual acuity and predictability were not predictive of videokeratography pattern. CONCLUSIONS: Most eyes in this study had an asymmetric videokeratography pattern 3 months after LASIK. Small but statistically significant differences were identified among the videokeratography patterns that potentially may affect postoperative quality of vision.

Adolescent↗
PubMed2000

Diurnal stability of refraction after implantation with intracorneal ring segments.

PURPOSE: To investigate diurnal changes in visual acuity and refraction in myopic eyes implanted with intracorneal ring segments (ICRS). SETTING: University of California San Diego Shiley Eye Center, La Jolla, California, and Emory University Vision Correction Center, Atlanta, Georgia, USA. METHODS: This prospective study involved 2 groups of patients who had ICRS (Intacs) implantation and a follow-up of at least 6 months. The first group included 102 eyes of 51 bilaterally treated patients; the second group, 32 eyes of 16 unilaterally treated patients. Examinations including visual acuity, manifest refraction, and videokeratography were done in the morning and evening at least 9 hours apart on a single day. Refractive changes were analyzed by power vectors; multivariate statistics were used to determine the significance of change in any component of the spectacle prescription. RESULTS: In the bilateral treatment group, 97 eyes (95%) were within 1 line of spectacle-corrected visual acuity from morning to evening. The mean change in manifest refraction was -0.14 +0.08 x 4 and in spherical equivalent, -0.10 diopters (D) (sigma = 0.3; range -0.750 to +0.875 D). Ninety-six eyes (94%) had a change in refraction within 0.50 D of spherical equivalent. There was no significant change in corneal power (P =.20). In the unilateral treatment group, there was no significant difference between treated and untreated eyes in changes in spectacle-corrected visual acuity, manifest refraction, or corneal power and toricity (P.05). CONCLUSION: No clinically significant diurnal variation in visual acuity or manifest refraction was observed after ICRS implantation or in untreated paired eyes. Moreover, the data suggest less diurnal change in visual acuity and refraction after ICRS implantation.

Circadian Rhythm↗
PubMed1999

Conjunctival deposits as an initial manifestation of sarcoidosis.

PURPOSE: To report conjunctival deposits as an initial manifestation of sarcoidosis. METHODS: Case reports. RESULTS: Two patients with bilateral bulbar conjunctival white deposits underwent conjunctival biopsy. The biopsy specimens showed noncaseating granulomas with prominent Schaumann bodies. Serum angiotensin-converting enzyme levels were increased in both patients. The first patient had abnormal results of pulmonary function tests. Sarcoidosis was diagnosed in both patients. CONCLUSIONS: Conjunctival deposits may represent the initial clinical manifestation of sarcoidosis.

Adult↗
PubMed1999

Complications of laser in situ keratomileusis for the correction of myopia.

OBJECTIVE: To determine the incidence and severity of complications from laser in situ keratomileusis (LASIK) for the correction of myopia by experienced and inexperienced surgeons. DESIGN: Prospective, observational clinical study. PARTICIPANTS: Fourteen surgeons and 1062 eyes of 574 myopic patients who desired surgical correction of myopia ranging from -2.00 to -22.50 diopters (D; mean, -7.57 D) and astigmatism no greater than 4.00 D participated in this study. INTERVENTION: Myopia was corrected with LASIK. Astigmatism was corrected with arcuate keratotomy at the same time as the initial procedure or subsequently. MAIN OUTCOME MEASURES: Primary outcome measures were change in best spectacle-corrected visual acuity (BSCVA) and the incidence of complications. RESULTS: Eyes were followed for a mean of 9.5 months after their last surgical procedure (range, 2 weeks-21 months). Three hundred eighty-one eyes (36%) underwent 468 enhancement procedures 3 months or more after the initial treatment. There were 27 (2.1%) intraoperative and 40 (3.1%) postoperative complications. Laser ablation was not performed during the initial treatment of 17 (1.6%) eyes because of intraoperative complications. Seventy-four eyes gained 2 or more lines of BSCVA, while 50 eyes lost 2 or more lines of BSCVA. Only three eyes lost two or more lines of BSCVA to a level worse than 20/40. One eye with a flap buttonhole (BSCVA 20/50) also had an epiretinal membrane. The second eye (BSCVA 20/60) had a flap buttonhole that may have been related to a previous corneal transplant. The third eye (-22.50 D before surgery) had a rhegmatogenous retinal detachment develop, reducing BSCVA from 20/60 to 20/200. The incidence of intraoperative complications decreased from 3.1% during the first 3 months to 0.7% during the last 9 months of the study (P = 0.02). CONCLUSIONS: LASIK is acceptably safe for the correction of myopia. Although complications occur in approximately 5% of cases, these rarely lead to visual loss of more than two Snellen lines and postoperative acuity below 20/40. Flap buttonholes were more likely to cause loss of BSCVA than free or incomplete flaps (P = 0.02); flap buttonholes may be more likely in eyes that have undergone previous surgery. Complication rates can be reduced as the surgical team gains experience.

Astigmatism↗
PubMed1999

Randomized bilateral comparison of excimer laser in situ keratomileusis and photorefractive keratectomy for 2.50 to 8.00 diopters of myopia.

OBJECTIVE: To compare effectiveness, safety, and stability of excimer laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for low-to-moderate myopia. DESIGN: Prospective, randomized, bilateral study. PARTICIPANTS: Thirty-three patients with a manifest refraction of -2.50 to -8.00 diopters (D) participated. INTERVENTION: For each patient, one eye received LASIK and the other received PRK. The first eye treated, and surgical method in the first eye, were randomized. Both eyes were treated by the same surgeon during the same operative session with a Summit Omnimed I laser (6-mm-diameter ablation) and a Chiron Automated Corneal Shaper. Follow-up was 90% at 1 and 2 years. RESULTS: At baseline, mean (+/-standard deviation) spherical equivalent manifest refraction was -4.80 +/- 1.60 D in LASIK-treated eyes and -4.70 +/- 1.50 D in PRK-treated eyes. At 1 day after surgery, 81% of patients (21 eyes) reported no pain in the LASIK-treated eye, whereas no patient (0%) reported being pain-free in the PRK-treated eye. At 3 to 4 days after surgery, 18 (80%) LASIK-treated eyes either improved or remained within 1 line of baseline spectacle-corrected visual acuity; only 10 (45%) PRK-treated eyes achieved this result. At 2 years after surgery, 18 (61%) LASIK- and 10 (36%) PRK-treated eyes achieved an uncorrected visual acuity of 20/20 or better, with no statistically significant difference in refractive outcome between the two techniques. Quantitative videokeratography showed more regularity after LASIK. Complications were similar in the two groups. Patients preferred LASIK by a margin of 2 to 1 at 1 year but showed no preference at 2 years. CONCLUSIONS: Using a 6-mm-diameter single-pass, large area ablation and an automated microkeratome to treat myopia of -2.50 to -8.00 D with 1.00 D or less astigmatism in 1994, the authors used LASIK to produce a higher percentage of eyes with an uncorrected visual acuity of 20/20 or better, more regular postoperative corneal topography, less postoperative pain, and more rapid recovery of baseline spectacle-corrected visual acuity than PRK. Both LASIK and PRK achieved successful correction of low-to-moderate myopia at 1 and 2 years after surgery.

Adolescent↗
PubMed1999

Prospective randomized comparison of simultaneous and sequential bilateral laser in situ keratomileusis for the correction of myopia.

OBJECTIVE: To study the safety and efficacy of simultaneous bilateral laser in situ keratomileusis (LASIK). DESIGN: Prospective randomized clinical trial. PARTICIPANTS: Fourteen surgeons and 714 consecutive eyes of 357 patients who desired surgical correction of myopia ranging from -2.00 to -22.50 diopters. INTERVENTION: Patients were randomized to simultaneous or sequential bilateral LASIK. MAIN OUTCOME MEASURES: Primary outcome measures were safety and efficacy. Procedure safety was assessed, for simultaneous and sequential groups, by comparison of intraoperative and postoperative complication rates and the percentage of eyes losing two or more lines of spectacle-corrected visual acuity. Procedure efficacy was assessed by comparison of the percentage of eyes with uncorrected visual acuity better than or equal to 20/20 and 20/40 and the percentage of eyes within +/-0.50 and +/-1.00 diopters of intended outcome. RESULTS: Three hundred seventy-eight eyes were enrolled in the simultaneous group, and 331 eyes were enrolled in the sequential group. Mean follow-up was 10 months (+/-4.2 months standard deviation; range, 2 weeks-22 months). There was no significant difference in intraoperative complication rate (P = 0.55), loss of two or more lines of spectacle-corrected visual acuity (P = 0.87), or percentage of eyes within +/-0.50 diopters of intended correction (P = 0.17) between simultaneous and sequential groups. Postoperative complications were not significantly different in the two groups except for the unexplained more frequent epithelial ingrowth in the simultaneous group (2.9%) than in the sequential group (0.6%). The adjusted odds ratio for epithelial ingrowth in the simultaneous group was 1.02 (95% confidence interval, 1.01-1.08). There was no increased likelihood of epithelial ingrowth in the second of two simultaneously treated eyes (P = 0.95). CONCLUSION: The outcomes and complications of performing bilateral simultaneous LASIK were not significantly different from those of sequential treatments, with the unexplained exception of more frequent epithelial ingrowth in the simultaneous group.

Adolescent↗
PubMed1999

Diurnal fluctuations in corneal topography 10 years after radial keratotomy in the Prospective Evaluation of Radial Keratotomy Study.

PURPOSE: To correlate clinically observed fluctuations in manifest refraction, visual acuity, keratometry, and intraocular pressure (IOP) with changes in the anterior corneal surface as measured by videokeratography in patients 10 years after radial keratotomy (RK). SETTING: Four clinical centers in the United States that participated in the Prospective Evaluation of Radial Keratotomy (PERK) study. METHODS: Thirty-two eyes of 20 PERK patients who noted diurnal fluctuations in vision had clinical examination and videokeratography (TMS-1, Computed Anatomy Inc.) in the morning and evening of the same day a mean of 10.3 years (range 7.8 to 11.7 years) after RK. The videokeratographs were analyzed in terms of various indexes generated by custom-designed software. Morning-to-evening changes in the means of the various clinical and videokeratographic values were assessed using pairwise methods. RESULTS: The mean increase in myopia was 0.36 diopters (D) +/- 0.58 (SD) from morning to evening (P < .01). Analysis of the videokeratographs showed a corresponding increase in average corneal power (ACP), reflecting a steepening of 0.52 +/- 0.45 D (P < .001). The change in ACP was correlated with a change in the manifest spherical equivalent refraction (R = 0.39, P = .03) and a change in best spectacle-corrected visual acuity (R = 0.38, P = .03) over the same period. Similarly, simulated keratometry (SimK) readings correlated with the change in the manifest spherical equivalent refraction (R = 0.38, P = .03 for SimK1; R = 0.37, P = .35 for SimK2; R = 0.4, P = .02 for average SimK), although the standard clinical keratometric data did not (P = .26 for K1, P = .11 for K2, and P = .09 for the mean K). The elevation depression magnitude, a measure of the low-frequency irregularities of the cornea, showed a decrease of 0.32 +/- 1.59, which also correlated with the change in the manifest spherical equivalent refraction (R = 0.37, P = .04). Intraocular pressure tended to decrease from morning to evening (mean change of -0.97 +/- 3.29 mm Hg), but the difference was not significant. Variations in IOP in individual patients, however, were correlated with changes in the manifest spherical equivalent refraction (R = 0.37, P = .04). CONCLUSIONS: Diurnal fluctuations in corneal topographic indexes can be used to evaluate the diurnal fluctuations in refraction and visual acuity after RK. The study findings provide statistical support for the idea that IOP contributes to the diurnal fluctuation in visual acuity after RK.

Adult↗
PubMed1998

Effects of laser in situ keratomileusis (LASIK) on the corneal endothelium.

PURPOSE: To assess the effects of laser in situ keratomileusis (LASIK) on the corneal endothelium. METHODS: In a prospective study, the corneal endothelium of 98 eyes of 65 consecutive patients (mean age, 41 years; range, 22 to 66 years) was photographed before, 2 weeks after, and 12 weeks after LASIK for the correction of 2.75 to 14.5 diopters of myopia. Theoretical ablation depths were 200 to 330 microm below the corneal surface. Cell density, coefficient of variation, and percent of hexagonal cells were determined using 150 to 200 cells from each image. Eighty-eight eyes (91%) of 59 patients had a history of contact lens wear. RESULTS: The mean+/-SD preoperative endothelial cell density was 2,549+/-365 cells per mm2, and the mean coefficient of variation was 0.35+/-0.06. There was no statistically significant change in the mean endothelial cell density or mean coefficient of variation of cell size at the 2-week (2,561+/-360 cells per mm2 and 0.35+/-0.06) or 12-week (2,541+/-364 cells per mm2 and 0.35+/-0.05) postoperative examinations. The percent of hexagonal cells was not significantly changed 2 weeks postoperatively; however, 12 weeks postoperatively (P=.0413, two-tailed t test), the percent of hexagonal cells was decreased by 1%. CONCLUSIONS: Corneal endothelial cell density and morphology were unchanged 2 and 12 weeks after LASIK for the correction of up to 14.5 diopters of myopia. In this LASIK study, the correction of up to 14.5 diopters of myopia appears to cause no clinically significant effect on corneal endothelial cell density or morphology.

Adult↗
PubMed1998

Prospective comparison of single-zone and multizone laser in situ keratomileusis for the correction of low myopia.

OBJECTIVE: This study aimed to determine whether there is a true difference in predictability between single-zone and multizone laser in situ keratomileusis (LASIK) for the correction of low myopia or whether any difference in predictability is because of a need for separate clinical nomograms for the two treatments. DESIGN: A prospective, randomized, clinical trial. PARTICIPANTS: Fourteen surgeons and 190 eyes of 95 patients with myopia who desired surgical correction of myopia ranging from -2.00 to -7.00 diopters (D) participated. INTERVENTION: Fellow eyes of patients with myopia undergoing bilateral simultaneous LASIK were randomized to single-zone and multizone ablation. Astigmatism was not corrected at the time of LASIK. MAIN OUTCOME MEASURES: Predictability, postoperative videokeratography, and contrast sensitivity were assessed at 3 months after surgery. RESULTS: At 3 months, r2 values relating laser setting to change in spherical equivalent refraction were 0.78 for single-zone and 0.76 for multizone ablation; mean outcome with respect to intended was -0.84 D (0.65 standard deviation [SD]) for single-zone and -0.62 D (0.78 SD) for multizone eyes (P = 0.035). There was no relationship between single-zone and multizone ablation and the likelihood of asymmetric postoperative videokeratography (P = 0.83). The only difference in contrast sensitivity was a significantly greater decrease in log contrast for multizone eyes at 12 cyc/deg under undilated conditions. CONCLUSIONS: There is no true difference in predictability between single-zone and multizone LASIK for the correction of low myopia. Separate clinical nomograms for single-zone and multizone LASIK should eliminate the difference in predictability that was observed in this clinical trial.

Adolescent↗
PubMed1998

Revising a myth.

Explore the source record for details and available documents.

Cornea↗
PubMed1998

Keratocyte repopulation in epikeratoplasty specimens.

PURPOSE: To study the histology and pattern of keratocyte repopulation of surgically removed human epikeratoplasty lenticules. METHODS: Removed epikeratoplasty lenticules and penetrating keratoplasty buttons that contained epikeratoplasty lenticules were evaluated for duration of epikeratoplasty, histologic and ultrastructural features, and average number of keratocytes per high-power microscopic field. The keratocyte density was compared with age-matched controls. RESULTS: Fifteen epikeratoplasty specimens from eight penetrating keratoplasties and seven removed lenticules were reviewed. The indications for keratoplasty were myopia, keratoconus, and aphakia. The lenticules were in place for 7-120 months, and the keratocyte count ranged from 14 to 40 per high-power field. Keratocyte density increased to 30-40 per high-power field, similar to age-matched controls, at approximately 48 months postoperatively, similar to the density of the controls. Keratocytes appeared to have migrated from the periphery to the center of the lenticules. CONCLUSIONS: Normal keratocyte density in epikeratoplasty lenticules is reached by approximately 48 months after surgery.

Adult↗
PubMed1997

Results of phase III excimer laser photorefractive keratectomy for myopia. The Summit PRK Study Group.

OBJECTIVE: The purpose of the study is to determine safety and efficacy outcomes of excimer laser photorefractive keratectomy (PRK) for the treatment of mild-to-moderate myopia. DESIGN: A prospective, multicenter, phase III clinical trial. PARTICIPANTS: A total of 701 eyes of 701 patients were entered in the study; 612 eyes were examined at 2 years after surgery. INTERVENTION: Intervention was photorefractive keratectomy using the Summit ExciMed UV200LA excimer laser (Summit Technology, Inc., Waltham, MA). The treatment zone diameter used was 4.5 mm in 251 eyes (35.8%) and 5 mm in 450 eyes (64.2%). Attempted corrections ranged from 1.50 to 6.00 diopters (D). MAIN OUTCOME MEASURES: Predictability and stability of refraction, uncorrected and spectacle-corrected visual acuity, refractive and keratometric astigmatism, corneal haze, contrast sensitivity, subjective reported problems of glare and halo, and patient satisfaction were the parameters measured. RESULTS: At 2 years, 407 (66.5%) eyes achieved 20/20 or better uncorrected visual acuity and 564 (92.5%) eyes achieved 20/40 or better visual acuity. Three hundred thirty-six (54.9%) eyes were within 0.5 D and 476 (77.8%) eyes were within 1.0 D of attempted correction. Stability of refraction improved with time; 86.8% of eyes were stable within 1.0 D from 6 to 12 months, 94% were stable from 12 to 18 months, and 96.3% were stable from 18 to 24 months. There was no evidence of progressive or late myopic or hyperopic refractive shifts. One hundred fourteen (18.6%) eyes gained 2 or more lines of spectacle-corrected visual acuity, whereas 42 (6.9%) eyes lost 2 or more lines; however, of the latter, 32 (76.2%) had spectacle-corrected visual acuity of 20/25 or better and 39 (92.9%) eyes had 20/40 or better. Four hundred forty-two (72.2%) corneas were clear, 138 (22.5%) showed trace haze, 20 (3.3%) mild haze, 9 (1.5%) moderate haze, and 3 (0.5%) marked haze. On patient questionnaires, 87 (29.7%) patients reported worsening of glare from preoperative baseline; 133 (50.1%) reported worsening of halo symptoms from baseline. CONCLUSIONS: Photorefractive keratectomy appears effective for myopic corrections of -1.50 to -6.00 D. Uncorrected visual acuity is maximized in most eyes by 3 months, although some patients require between 6 months and 1 year to attain their best postoperative uncorrected visual acuity and some may require from 1 to 2 years for stabilization of refraction. Refraction stabilizes progressively without evidence of late myopic or hyperopic refractive shifts. Optical sequelae of glare and halo occur in some patients treated with a 4.5- or 5-mm treatment zone.

Adult↗