Biomedical subjects
W A Lyle
Publications and source records attributed to W A Lyle.
Laser in situ keratomileusis with the VISX Star laser for myopia over -10.0 diopters.
PURPOSE: To evaluate the efficacy, predictability, stability, and safety of laser in situ keratomileusis (LASIK) for myopia over -10.00 diopters (D). SETTING: The Eye Institute of Utah, Salt Lake City, Utah, USA. METHODS: The prospective study included 332 eyes of 183 patients having LASIK with the VISX Star laser to correct myopia of -10.00 to -18.00 D. The eyes were divided into 3 groups according to the preoperative refraction: Group A (n = 208), -10.00 to -11.90 D; Group B (n = 94), -12.00 to -14.00 D; Group C (n = 30), -14.10 to -18.00 D. The mean follow-up was 12.0 months +/- 5.6 (SD) (range 6 to 37 months). RESULTS: Overall, the mean spherical equivalent decreased 96%, from -11.69 +/- 1.46 D preoperatively to -0.37 +/- 0.80 D postoperatively. The mean astigmatism decreased 72%, from 1.66 +/- 1.22 D to 0.46 +/- 0.53 D. At the last visit, 84.0% of eyes were within +/-1.00 D of emmetropia and 96.4% were within +/-2.00 D. An overcorrection of more than +1.00 D was experienced by 1.8% of patients. The uncorrected visual acuity (UCVA) was 20/20 or better in 45.8% of eyes and 20/40 or better in 89.5%. Six eyes (1.8%) lost 2 or more lines of best corrected visual acuity; this included 1 eye in which iatrogenic keratectasia developed 18 months after LASIK retreatment. Retreatment was done in 37.0% of eyes at a mean of 6.3 +/- 5.3 months (3 to 32 months) after the initial treatment. At the last examination, 86.0% of eyes in Groups A and B and 70.0% in Group C were within +/-1.00 D of emmetropia. A significant difference was found between Groups A and C (P =.032). The UCVA was 20/20 in 52.0% of Group A eyes, 38.0% of Group B eyes, and 23.0% of Group C eyes. The difference between Groups A and C was significant (P =.001), but the difference between Groups A and B was not (P =.055). CONCLUSIONS: In this study, LASIK was effective in correcting myopia up to -14.00 D. The efficacy, predictability, and safety were significantly less in eyes with myopia greater than -14.00 D.
Retreatment after initial laser in situ keratomileusis.
PURPOSE: To report the results of laser in situ keratomileusis (LASIK) retreatment in patients with primary undercorrection and with postoperative regression and to assess the efficacy and safety of LASIK retreatment. SETTING: The Eye Institute of Utah, Salt Lake City, Utah, USA. METHODS: The prospective study included 157 eyes of 108 patients. Using the VISX Star laser, retreatments were performed for undercorrection in 43 eyes (27%) and for regression in 114 eyes (73%). The mean follow-up was 15 months (range 6 to 28 months) after the initial surgery and 10 months (range 3 to 25 months) after the repeat LASIK procedure. RESULTS: Overall, the mean spherical equivalent (SE) was -6.11 +/- 2.35 diopters (D) (range -1.87 to -15.00 D) before LASIK and -1.28 +/- 0.57 D (range -0.50 to -3.25 D) prior to retreatment. At the last visit, it was -0.23 +/- 0.41 D (range -2.55 to 1.13 D). One hundred fifty-three eyes (97.5%) were within +/-1.00 D of emmetropia and 128 (81.5%), within +/-0.50 D. The uncorrected visual acuity was 20/20 or better in 68.8% of eyes and 20/40 or better in 98.1%. In all eyes, the best corrected visual acuity (BCVA) improved or remained within 1 line of the pre-revision level. However, 2 eyes (1.3%) lost 2 or more lines of pre-initial LASIK BCVA. Both eyes had a preoperative SE greater than -8.00 D; corneal irregularity was the cause of the decrease in vision. CONCLUSIONS: Several conclusions can be drawn from this study. First, LASIK retreatment is effective and safe for correcting undercorrection and regression after initial LASIK, and a good visual outcome is expected. Second, in most eyes, regression occurs within 6 months after the initial LASIK. However, regression can develop up to 2 years after LASIK. Third, multiple retreatments will be required in some patients. The outcome in these cases is promising.
Results of flap repositioning after laser in situ keratomileusis.
PURPOSE: To determine the incidence and severity of flap folds and displacement after laser in situ keratomileusis (LASIK) and assess the outcome of the flap repositioning procedure. SETTING: Eye Institute of Utah, Salt Lake City, Utah, USA. METHODS: Charts of 91 eyes of 87 patients that had flap repositioning were reviewed retrospectively. Four patients had bilateral procedures. RESULTS: The overall rate of flap repositioning was 0.91%. Fifty-six percent of flap folds occurred on the first postoperative day and 85%, within 1 week of the LASIK procedure. The latest flap repositioning was performed 150 days after LASIK. Blurred vision was the main symptom; this occurred in 72% of patients. Eighteen percent of eyes had loose epithelium at the time of LASIK. Dry eye was found in 42% of cases. Nineteen percent of eyes had multiple flap repositioning procedures. Flap folds induced a hyperopic change in refraction and increased astigmatism as well as irregular astigmatism. With the Automated Corneal Shaper(R) (ACS) microkeratome (Bausch & Lomb Surgical), 45% of folds were located in the superior part of the flap and 6% in the inferior part; 42% of folds were oriented horizontally and 17%, vertically; 23% of eyes had a superior gutter. With the Hansatome(R) (Bausch & Lomb Surgical) microkeratome, 73% of folds were central; 87% were oriented vertically and 6%, horizontally. The incidence of flap folds increased to 2.10% with the use of the Hansatome. With a mean follow-up of 8.3 months after flap repositioning (range 3 to 31 months), the uncorrected visual acuity was 20/20 in 59% of eyes and 20/40 in 88%. Three eyes (3%) lost 2 or more lines of best corrected visual acuity. The final spherical equivalent was -0.07 diopter (D) +/- 0.61 (SD), and 87% of eyes were within +/-1.00 D of emmetropia. CONCLUSION: Flap repositioning significantly restored the vision loss caused by flap folds and displacement. However, irregular astigmatism due to permanent residual folds remains the main factor affecting the visual and refractive outcome.
Interface fluid associated with diffuse lamellar keratitis and epithelial ingrowth after laser in situ keratomileusis.
We report a case in which diffuse interface keratitis began 1 week after bilateral uneventful laser in situ keratomileusis (LASIK). A layer of fluid in the interface with epithelial ingrowth was noted in the left eye 20 days postoperatively. The same complication occurred in the right eye 5 months after LASIK. Dry-eye syndrome and steroid-induced intraocular pressure elevation occurred in this patient with pre-existing ocular hypertension. A long course of interface inflammation was resistant to topical steroids. Surgical removal of the epithelial ingrowth and drainage of the fluid, combined with medical treatment, resulted in resolution of the inflammation. The cytopathologic examination of the fluid showed epithelial cells without signs of inflammation. The clinical features of this case represent a new complication of LASIK.
Hyperopic automated lamellar keratoplasty: complications and visual results.
OBJECTIVE: To examine the long-term safety and efficacy of hyperopic automated lamellar keratoplasty (H-ALK) for correction of primary hyperopia and for consecutive hyperopia following overcorrected myopic refractive surgery. METHODS: A prospective study was done on 67 eyes of 50 consecutive patients who underwent H-ALK between March 17, 1993, and August 18, 1995. Hyperopic automated lamellar keratoplasty was performed for primary hyperopia in 25 eyes (group 1) and for consecutive hyperopia after myopic refractive surgery in 42 eyes (group 2, radial keratotomy, 41 eyes, and myopic automated lamellar keratoplasty, 1 eye). The eyes were followed up for a mean+/-SD of 19.2+/-12.8 months (range, 3-49 months), 58 (87%) of them with 6 months' follow-up, and 45 (67%) of them with at least 1 year's follow-up. Twenty-one eyes were followed up for 2 to 4 years. RESULTS: The overall mean+/-SD preoperative spherical equivalent was +2.87+/-1.28 diopters (D). The mean+/-SD postoperative spherical equivalent was -0.03+/-1.42 D at 3 months, -0.42+/-2.25 D at 6 months, -0.55+/-3.00 D at 1 year, -1.58+/-1.53 D at 2 years, and -0.35+/-1.79 D at the last follow-up. A mean myopic shift of 0.50 D was noted between 3 months and 1 year, and of 1.00 D between 1 and 2 years. Hyperopia was meaningfully reduced and visual acuity was improved by H-ALK, especially for patients with primary hyperopia. Long-term refractive instability, however, is a serious problem with this procedure. In this series, 11 (26%) of 42 eyes in which H-ALK was performed for consecutive hyperopia developed iatrogenic keratoconus. CONCLUSION: Based on this study, the long-term instability of H-ALK and the high incidence of iatrogenic keratoconus following the procedure should discourage its use, especially for consecutive hyperopia following radial keratotomy.
Intraocular lens power prediction in patients who undergo cataract surgery following previous radial keratotomy.
BACKGROUND: Previous experience has shown that there is no technical difficulty in performing cataract surgery on patients who have previously undergone radial keratotomy. However, some researchers have reported inaccuracy in intraocular lens (IOL) power selection. OBJECTIVES: To assess the visual and refractive outcomes of our patients and to compare different formulas and variables to improve accuracy in power determination. MAIN OUTCOME MEASURES: Ten eyes subjected to phacoemulsification with in-the-bag posterior chamber lens implantation 79 months (range, 36-118 months) after radial keratotomy were evaluated in this study. The IOL power was retrospectively calculated for each eye using the Binkhorst, SRK II, and Holladay formulas with the current keratometry reading, the refractive-derived keratometric value (K), the current refractive-derived K, and the adjusted K. The final refractive result was used as a criterion to judge the accuracy and predictability for each approach. RESULTS: Three eyes underwent an IOL exchange after initial surgery. Among the 7 eyes that did not undergo an IOL exchange, a hyperopic shift that regressed approximately 3 months after surgery occurred in the early postoperative period. At the final examination, 5 of the 7 eyes had a hyperopic error, with 2 eyes showing more than 1.00 diopter (D). Overall, in an average of 27 months (range, 9-80 months) of follow-up, an uncorrected visual acuity of 20/40 or better was obtained in 6 (60%) of the eyes. All 10 eyes had a 20/25 or better postoperative best-corrected visual acuity. The mean (+/-SD) spherical equivalent refraction was changed from -0.78 +/- 3.49 D preoperatively to 0.45 +/- 1.31 D postoperatively. We found that the Binkhorst and Holladay formulas are more accurate than the SRK II formula. With the use of an adjusted K (ie, the current average K minus 1.0 D) in combination with the Binkhorst and Holladay formulas, most of the eyes would achieve a refraction of -2.00 to +0.50 D. CONCLUSIONS: A corneal flattening effect caused by cataract surgery tends to occur in eyes that have undergone previous radial keratotomy. The use of an average between the Binkhorst and Holladay formulas, aiming for -0.75 D with an adjusted K, seems to be a more accurate and predictable method for IOL power calculation. This approach could reduce the chance of postoperative hyperopia.
Clear lens extraction to correct hyperopia.
PURPOSE: To evaluate the effectiveness and safety of clear lens extraction with intraocular lens (IOL) implantation to correct hyperopia and to determine the most accurate and predictable method of IOL power selection. SETTING: The Eye Institute of Utah, Salt Lake City, Utah, USA. METHODS: The outcome of 20 phacoemulsification and IOL implantation procedures was assessed at a mean follow-up of 23.2 months (range 3 to 60 months). Intraocular lens power and predicted refraction were retrospectively evaluated in each eye with the SRK II and Holladay formulas with different attempted refractions based on the stabilized postoperative refraction. RESULTS: Uncorrected visual acuity (UCVA) improved from 20/200 preoperatively to 20/30 postoperatively. At the final examination, 89% of eyes achieved 20/40 or better UCVA. All eyes had 20/25 or better best corrected visual acuity (BCVA). No eye lost two or more Snellen lines of BCVA. There were no surgical or postoperative complications. The Holladay formula was more accurate than the SRK II formula. With the Holladay formula aiming for -1.00 diopter (D), the predicted mean postoperative spherical equivalent would be -0.21 D +/- 0.89 (SD); with the SRK II aiming for -1.50 D, it would be +0.43 +/- 1.10 D. The Holladay formula reduced the chance of postoperative residual hyperopia. CONCLUSION: Clear lens extraction with IOL implantation was an effective, safe procedure for the correction of hyperopia. However, this method was less accurate and less predictable for hyperopia below +3.00 D. With the Holladay formula aiming for -1.00 D, good visual and refractive results can be expected. Further study with a larger sample of patients and longer follow-up is needed to assess long-term safety and effectiveness.
Prospective evaluation of early visual and refractive effects with small clear corneal incision for cataract surgery.
PURPOSE: To evaluate the early postoperative visual and refractive effects of a 3.25 mm clear corneal self-sealing incision with foldable intraocular lens implantation. SETTING: The Eye Institute of Utah, Salt Lake City. METHODS: Visual acuity and refraction in 50 eyes of 50 consecutive patients having clear corneal phacoemulsification were prospectively evaluated at 30 minutes, 1 day, 1 week, and 1 and 3 months postoperatively. RESULTS: Uncorrected visual acuity of 20/40 or better was obtained in 38% of eyes 30 minutes after surgery, 52% at 1 day, and 89% at 3 months. There was no significant refractive cylinder change (P = .093). Visual rehabilitation and refractive stability were rapid, and induced astigmatism was low. A strong positive correlation was found between refraction at 30 minutes and that at 3 months after surgery (R = .5788, P = .0003). The visual and refractive examination performed 30 minutes after surgery could help early detection of incorrect IOL power selection. CONCLUSION: The low induced astigmatism, excellent early visual acuity, and lack of surgical complications support the concept and justify the use of small temporal corneal incisions for cataract surgery.
Phacoemulsification with intraocular lens implantation in high myopia.
PURPOSE: To assess phacoemulsification and posterior chamber intraocular lens (IOL) implantation in highly myopic eyes and to compare the results of sutureless scleral tunnel incision and sutured scleral incision techniques. SETTING: The Eye Institute of Utah, Salt Lake City. METHODS: A series of 109 highly myopic eyes (axial length over 26.00 mm) were reviewed at a mean postoperative follow-up of 27 months. RESULTS: Postoperative corrected visual acuity was 20/40 or better in 94% of eyes, and uncorrected visual acuity was 20/40 or better in 77% of eyes. Posterior capsule opacification developed in 50% of eyes; 95% of these had neodymium:YAG (Nd:YAG) laser capsulotomy. Cystoid macular edema occurred in two eyes, and one eye developed retinal detachment following Nd:YAG capsulotomy. Eyes that had sutureless scleral tunnel incisions attained earlier postoperative rehabilitation of visual acuity and stabilization of astigmatism than did patients who had sutured scleral incisions. CONCLUSIONS: The results of this study of highly myopic eyes indicate that treating retinal pathology preoperatively and using the sutureless procedure, phacoemulsification, and in-the-bag IOL placement lead to good visual outcome, a lower rate of retinal complications, and a more stable wound.
Clear lens extraction for the correction of high refractive error.
The results of clear lens extraction and posterior chamber intraocular lens implantation in 31 eyes with high myopia and six eyes with high hyperopia were reviewed. In the myopic group, 77% of eyes achieved 20/40 or better uncorrected postoperative visual acuity and 97% achieved 20/40 or better corrected acuity. Sixty-eight percent of eyes were within 1.0 diopter (D) of emmetropia and 90% were within 2.0 D. Astigmatic keratotomy (four eyes) and radial keratotomy (one eye) were performed for postoperative refractive errors. Intraocular lens exchange was necessary to correct power in one case. In the hyperopic group, all six eyes achieved 20/40 or better uncorrected postoperative visual acuity and all were within 1.0 D of emmetropia. During the 20-month mean follow-up, no retinal detachment or cystoid macular edema was observed. Posterior capsule opacification was the major complication and it developed faster than reported in other studies.
Secondary intraocular lens implantation: anterior chamber vs posterior chamber lenses.
We retrospectively studied 348 cases of secondary lens implantation, comparing data obtained from 234 eyes that received anterior chamber intraocular lenses (AC-IOLs) with 114 that received posterior chamber lenses (PC-IOLs), with a mean follow up of 19.5 months (range, 2 to 77 months). Visual acuity was similar in these two groups both before (P = .278) and after surgery (P = .771). Overall, 83% of the eyes had a postoperative acuity of 20/40 or better. In the eyes without preexisting pathology, 93% of those with AC-IOLs and 91% of those with PC-IOLs had this level of postoperative acuity. The incidence of complications in these two groups did not differ significantly. Our study suggests that one-piece flexible open-loop AC-IOLs pose no greater threat than PC-IOLs with respect to visual outcome in secondary implantation. Careful preoperative evaluation of the cornea, retina, and vitreous face will allow selection of the optimum lens style.
An analysis of intraocular lens exchange.
We present an analysis of 101 eyes of 98 consecutive patients who underwent intraocular lens (IOL) exchange. The period of follow up ranged from 6 to 71 months (mean, 23 months). Bullous keratopathy was the leading (86.7%) indication for IOL exchange in 45 eyes that had combined penetrating keratoplasty (PKP) and IOL exchange (PKP group). Lens dislocation (36%) and incorrect power (25%) were the most frequent indications for IOL exchange without PKP (56 eyes) (NPKP group). A final visual acuity of 20/40 or better was achieved in 50.5% of the 101 eyes, with 88% having two lines of improvement or remaining within one line of the pre-exchange acuity. The geometric mean visual acuity was significantly improved, from 20/273 preoperatively to 20/125 postoperatively, in the PKP group (P less than .001), and from 20/61 to 20/43 in the NPKP group (P = .001). The main reason for vision less than 20/200 in the 23 eyes in the PKP group was glaucoma (nine eyes) and bullous keratopathy (eight eyes). In the NPKP group, seven eyes (four due to cystoid macular edema, CME) had a visual acuity less than 20/200. Posterior chamber (PC) IOL implantation was associated with significantly better visual acuity than anterior chamber (AC) IOL implantation when performed at IOL exchange (P = .004). The most common complications encountered with IOL exchange were CME (17.8%), hyphema (15.8%), glaucoma (10.9%) and PC opacity (8.9%).
Comparison of a 3- and 6-mm incision in combined phacoemulsification and trabeculectomy.
We studied 216 eyes of 160 patients who underwent combined phacoemulsification and posterior chamber intraocular lens implantation with trabeculectomy. The mean follow-up was 18.7 months, with a minimum follow-up of six months. To assess the safety and efficacy of a recently developed 3-mm incision procedure with foldable intraocular lens implantation (phacotrabeculectomy), we compared 104 eyes subjected to this procedure with 112 eyes subjected to a 6-mm procedure at different follow-up periods. Intraocular pressure control (less than 21 mm Hg) was attained in 44 of 46 eyes (96%) in the 3-mm group and 71 of 76 eyes (93%) in the 6-mm group at one year postoperatively. Visual acuity of 20/40 or better was attained in 40 of 46 eyes (87%) in the 3-mm group and 66 of 76 eyes (87%) in the 6-mm group. The incidence of postoperative complication was significantly lower (P less than .001) and visual acuity in the early postoperative period was significantly better (P less than .01) in the 3-mm incision group than in the comparison group.
Meaningful evaluation of refractive surgery.
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Operating room retinoscopy.
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A new phacoemulsification technique for in-the-bag IOL placement.
The standard phacoemulsification procedure includes capsulotomy with an irrigating cystotome and cortical cleanup with an irrigation/aspiration handpiece. While this is an effective technique, it produces ill-defined capsule edges that make in-the-bag placement of the implant difficult. We describe a technique that facilitates identification of capsular flaps by using scissors for the anterior capsulotomy, followed by cortical cleanup with the Gills technique and in-the-bag placement of the implant.
Secondary and exchange posterior chamber lens implantation.
A retrospective chart review of 34 secondary or exchange posterior chamber lens implantations was performed. Overall 94% of the patients achieved a visual acuity of 20/40 or better at six to 12 months postoperative. Associated intraoperative procedures included lens implant removal for exchange (50%), iris suture (41%), posterior capsule polishing (24%) or discussion (24%), and anterior vitrectomy (15%). The postoperative complications included retinal detachment (6%), persistent clinical cystoid macular edema (3%), posterior capsular opacification (3%), failure to fixate requiring iris suture (3%), hyphema (3%), and pupil capture (3%). Secondary and exchange posterior chamber lens implantation can be performed with satisfactory visual acuity results but there is a real rate of complication that needs to be considered by the surgeon and patient who is contemplating the operation.