Arcuate keratotomy to treat corneal astigmatism after cataract surgery: a prospective evaluation of predictability and effectiveness

OBJECTIVE: Although several nomograms are available for the incisional keratotomy to correct naturally occurring astigmatism, astigmatic keratotomy in eyes after cataract surgery has not been well analyzed. The predictability and effectiveness of arcuate keratotomy in pseudophakic eyes were studied. DESIGN: A prospective, multicenter study. PARTICIPANTS: One hundred four eyes of 86 patients with residual corneal astigmatism of 1.5 diopters (D) or more after cataract surgery were examined. INTERVENTION: Arcuate keratotomy was performed in nine centers by nine surgeons. MAIN OUTCOME MEASURES: The amount of astigmatic correction was calculated using the vector analysis of preoperative and 6-month postoperative refractive cylinder results. RESULTS: Multiple regression analysis showed that optical zone size, number of incisions, and incision length had significant correlations with the amount of astigmatic correction. The regression equation was expressed as effects = (-0.643 x optical zone size) + (0.998 x incision number) + (0.057 x incision length) + 2.356. The parameter of predictability (r2: 35%) was lower than that reported for congenital astigmatism (48 to approximately 56%). A new nomogram was derived based on the multiple regression equation. CONCLUSIONS: Astigmatic keratotomy in pseudophakic eyes is less predictable than that in eyes with idiopathic astigmatism, but the procedure is sufficiently effective in reducing the residual astigmatism after cataract surgery. Individual nomograms are necessary for astigmatic keratotomy in eyes with naturally occurring and postsurgical astigmatism.     

Refractive outcome following radial keratotomy and combined radial and astigmatic keratotomy

PURPOSE: To determine whether the visual and refractive outcomes of combined astigmatic and radial keratotomy (AK/RK) procedures was different from that following RK for the correction of naturally occurring compound myopic astigmatism and spherical myopia. SETTING: Private professional practice, San Diego, California, USA. METHODS: The computer database of all incisional procedures performed by one surgeon over 10 years was reviewed to compare the visual acuity outcome of AK/RK and RK procedures. Enhancement procedures were excluded. Only data from the last office visits were analyzed to establish the relationship between visual acuity and type of keratotomy procedure performed. A multiple regression model was constructed, which included covariates of age, postoperative keratometric cylinder, and postoperative refraction. RESULTS: After controlling for covariates, the AK/RK population had significantly lower postoperative uncorrected visual acuity levels than the RK population (P < .03) after one operation (prior to enhancement surgery). CONCLUSIONS: Using the nomograms for myopia correction for unenhanced RK cases, combined AK and RK procedures appeared to reduce the expected visual results. Surgeons may consider modifying surgical nomograms to account for the expected spherical undercorrection that can occur when myopia and astigmatism are corrected simultaneously.     

Two-incision radial keratotomy for low myopia with astigmatism

PURPOSE: To evaluate the effectiveness of two-incision radial keratotomy (RK) in correcting low-magnitude refractive myopic astigmatism. SETTING: Two clinical study sites, one in St. Louis, Missouri, USA, the other in Caracas, Venezuela. METHODS: Fifty-seven eyes of 43 patients with low-magnitude myopic astigmatism had two-incision RK at one of two clinical study sites. In the initial phase of this series, 10 eyes with amblyopia at the 20/30 level had surgery at one center. Refractive keratotomy was performed with the radial incision placed in the plus cylinder axis of refraction. This axis was verified as the meridian of greatest corneal curvature by standard keratometry and computer-assisted corneal topographic analysis. Two eyes received a second operation (enhancement). RESULTS: Mean follow-up was 11.1 months (range 6 to 12 months). Mean preoperative and postoperative myopic spherical equivalent measured -1.42 diopters (D) +/- 0.51 (SD) and -0.14 +/- 0.39 D, respectively; the mean reduction was 1.28 +/- 0.59 D (P = .0001). Mean preoperative and postoperative refractive astigmatism was 1.41 +/- 0.45 D and 0.48 +/- 0.33 D, respectively (P = .0001). Mean preoperative and postoperative keratometric astigmatism was 1.26 +/- 0.54 D and 0.31 +/- 0.35 D, respectively, a mean reduction of 0.95 D (P = .0001). The surgical meridian was flattened by an average of 2.06 D by keratometry and the orthogonal meridian, by an average of 1.10 D. Preoperative uncorrected visual acuity (UCVA) was 20/40 or better in five (9%) eyes (range counting fingers to 20/40). Postoperative UCVA acuity was 20/40 or better in all eyes (mean acuity 20/25). In the nonamblyopic subgroup mean postoperative UCVA was 20/24. CONCLUSIONS: A limited number of radial incisions placed in the topographically confirmed axis of greatest curvature are effective in the treatment of low-magnitude myopic astigmatism.     

Surgical correction of postkeratoplasty astigmatism with the Hanna arcitome

PURPOSE: To report the results of arcuate keratotomy performed with the Hanna arcitome in patients with postkeratoplasty astigmatism. SETTING: Department of Ophthalmology, Saint-Antoine Hospital, Paris VI University, Paris, France. METHODS: This retrospective study comprised 22 eyes (22 patients) with postkeratoplasty astigmatism. Paired symmetrical arcuate keratotomy was performed with the Hanna arcitome. Outcome measures included refraction, videokeratography, and keratometry. RESULTS: At 6.6 months +/- 8.9 (SD) after surgery, the mean increase in best spectacle-corrected visual acuity (BSCVA) was 2.1 +/- 2.4 lines. Thirteen eyes gained 2 lines or more of BSCVA, and 15 gained 3 lines or more of uncorrected visual acuity. Two patients had a decrease in BSCVA: 1 had lens opacification unrelated to arcuate keratotomy and 1, increased corneal irregularity. Mean refractive astigmatism was 6.94 +/- 2.11 diopters (D) preoperatively and 3.85 +/- 1.95 D postoperatively (P < .01). Mean change in keratometric astigmatism was -51 +/- 36%. Astigmatism decreased in 21 eyes as measured by manifest refraction, keratometry, and videokeratography; it increased in 1 cornea with a microperforation. CONCLUSIONS: The results of arcuate keratotomy performed with the Hanna arcitome were comparable to those with freehand relaxing incisions. The instrument made safer and more uniform arcuate incisions than a freehand technique.     

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%.     

Mechanisms of central color vision

PURPOSE: To evaluate the effectiveness of limbal relaxing incisions (LRIs) for correcting corneal astigmatism during cataract surgery. SETTING: Cullen Eye Institute, Houston, Texas, USA. METHODS: In 12 eyes of 11 patients, cataract surgery was combined with LRIs. The LRIs were made according to a modified Gills nomogram and were based on preoperative corneal astigmatism determined with standard keratometry and computerized videokeratography (EyeSys Corneal Analysis System Version 3.2). RESULTS: The mean preoperative keratometric cylinder was 2.46 +/- 0.81 diopters (D). At 1 month postoperatively, mean arithmetic reduction in keratometric cylinder was 1.12 +/- 0.74 D, and the with-the-wound (WTW) change (calculated by Holladay, Cravy, Koch vector analysis formula) was -0.70 +/- 0.44. From 1 day to 1 month postoperatively, there was 0.55 D of WTW regression with minimal change in the mean cylindrical axis. There were no overcorrections. CONCLUSION: Limbal relaxing incisions are a practical, simple, and forgiving approach to the correction of astigmatism during cataract surgery.     

Ellipsoidal fitting of corneal topography data after arcuate keratotomies with compression sutures

BACKGROUND AND OBJECTIVE: After paired arcuate keratotomies and compression sutures (AK) for treatment of high postkeratoplasty astigmatism, corneal topography tends to be irregular. The purpose of this study was to demonstrate a mathematical method for approximation of discrete corneal topography power data with an ellipsoid for better appreciation of the clinical outcome after AK. PATIENTS AND METHODS: Thirty-one eyes of 28 consecutive patient who underwent AK for excessive postkeratoplasty astigmatism were studied. Regular keratometry, corneal topography (TMS-1), subjective refraction, and best-corrected visual acuity (VA) were assessed preoperatively and at 1 week and 1 year postoperatively. A simplex algorithm was applied for fitting an ellipsoidal surface to raw corneal topography power data. A set of parameters (meridional power, axis, and asphericity) were calculated. The cylinder of subjective refraction was correlated with the keratometric readings, the simulated keratometry (SimK) of the topography system, and the respective parameters of the model surface. RESULTS: Keratometric astigmatism and the cylinder of the model surface decreased from 8.1 +/- 3.2 and 7.9 +/- 2.9 D preoperatively to 4.5 +/- 2.1 and 5.3 +/- 2.0 D after 1 year, respectively. The asphericity in both meridional cross sections changed from a prolate ellipse preoperatively to an ablate ellipse at the early postoperative follow-up stage. Regarding the cylinder axis, there was a significant correlation of the model surface with the refractive cylinder at all examinations (P < .05), whereas there was no significant correlation of the SimK axis and the refractive cylinder axis. CONCLUSION: The approximation of corneal topography power data with an ellipsoidal model surface renders reconstruction of clinically relevant corneal topography parameters, including corneal asphericity with a marked data compression. Even in markedly irregular corneal surfaces, such as after AK, the correlation of amount/axis of refractive cylinder with the model surface parameters is more accurate than it is with respective SimK values of corneal topography analysis.     

Human rectal absorption of short- and medium-chain C2-C10 fatty acids

PURPOSE: To study the effects of running suture adjustment for reduction of astigmatism after penetrating keratoplasty. Suture adjustments performed during surgery and during the early postoperative and late postoperative periods were retrospectively compared. METHODS: We studied 53 patients who received running suture adjustment after penetrating keratoplasty, either intraoperatively (ISA group, n = 18), early (< 2 weeks) postoperatively (EPSA group, n = 19), or late (> 1 month) postoperatively (LPSA group, n = 16). Refractive and topographic astigmatism and corneal topography were examined at 1, 3, and 6 months after surgery. RESULTS: Overall mean refractive astigmatism and topographic astigmatism at 6 months were 2.55 +/- 1.61 D and 3.12 +/- 1.89 D, respectively (mean +/- SD). The mean refractive astigmatism and topographic astigmatism were 1.88 +/- 1.04 D and 2.35 +/- 1.35 D in the ISA group, 2.32 +/- 1.17 D and 2.70 +/- 1.21 D in the EPSA group, and 3.01 +/- 1.62 D and 4.62 +/- 2.51 D in the LPSA group, respectively (mean +/- SD). The LPSA group demonstrated significantly increased topographic astigmatism compared to the ISA group (p = 0.0048) and the EPSA group (p = 0.015). Although 31.6 and 25.0% of the EPSA and LPSA groups, respectively, did not require postoperative suture adjustments, more eyes (10/18 eyes, 55.6%) in the ISA group did not require the procedure. CONCLUSIONS: Early postoperative suture adjustment was more effective than late postoperative adjustment. Intraoperative suture adjustment may further reduce final astigmatism and the necessity for postoperative suture manipulation.     

Correlation of pituitary hormones in serum of male patients with fertility problems

The advent of the excimer laser has brought about the potential for improved vision in many individuals with myopia and astigmatism. However, photoastigmatic refractive keratectomy (PARK) remains a matter of controversy. The purpose of our study was to determine the predictability of VISX 20/20 excimer laser photorefractive keratectomy in the treatment of myopic astigmatism. PATIENTS AND METHODS: Our study comprised 31 eyes of 22 patients with myopic astigmatism. All patients underwent treatment with a VISX 20/20 excimer laser and were followed up for 6 months. Complete 12-month follow-up data were available from 18 eyes. Park was performed in eyes with myopia between -1.5 and -10.0 D and with astigmatism between -0.5 and -5.5 D. Thus, the corresponding spherical equivalent ranged from -1.75 to -10.5 D. RESULTS: Six months postoperatively, 21/31 (62%) eyes were within +/- 1.0 D of the target refraction and 13/31 (42%) within +/- 0.5 D of the target refraction. In 13 of 15 eyes (87%) with myopia less than -6.0 D, an uncorrected visual acuity of at least 0.8 was noted. In eyes with myopia greater than -6.0 D, 9/16 (56%) showed an uncorrected visual acuity of at least 0.5. Six months after PARK, an increase of one line on the Snellen Visual Acuity Chart was observed in 8/31 (26%) and an increase of two lines was noted in eyes 3/31 (10%). One of 31 eyes (3%) showed an increase of three lines. A decrease in visual acuity of 1 line on the Snellen Visual Acuity Chart was found in 4/31 (13%), and in 3/31 eyes (10%) a decrease of 2-4 lines was noted. Overall, we observed a statistically significant reduction of astigmatism from 1.93 +/- 1.43 D to 0.93 +/- 0.63 D. Reduction of corneal astigmatism less than -1.25 D was not statistically significant. In eyes with astigmatism ranging from -1.25 to -2.5 D or greater than -2.75 D, a significant reduction of the mean astigmatism was noted. The postoperative regression of astigmatic correction was low. However, an axis shift of more than 15 degrees was found in 42%/35% of eyes by subjective refraction (miosis/cycloplegia) and in 33% in corneal topography. No central islands were noted. CONCLUSION: Photoastigmatic refractive keratectomy (PARK) constitutes a potential means of correcting myopic astigmatism. In eyes with astigmatism greater than -1.0 D a significant reduction of 60% of the mean astigmatism was noted. However, the considerable proportion of eyes with a postoperative axis shift greater than 15 degrees and a decrease in visual acuity of two or more lines indicates that further research is needed on excimer laser surgery to improve the reliability and safety.     

Fruit consumption, fitness, and cardiovascular health in female adolescents: the Penn State Young Women''s Health Study

OBJECTIVE: The objective of this study was to determine the outcome of early and late suture removal after the triple procedure (i.e., penetrating keratoplasty, cataract extraction, lens implant). DESIGN AND PARTICIPANTS: The refractive and keratometric results of 106 eyes undergoing the triple procedure were reviewed. The target postoperative refractive error was -1 diopter (D). RESULTS: Average length of follow-up was 40.3 months. Twenty eyes had sutures removed early (<18 months after surgery), 39 had sutures removed late (> or = 18 months after surgery), and 47 had sutures still intact at last follow-up. A best spectacle-corrected visual acuity of 20/40 or better was achieved in 90% of eyes with sutures removed early, 82.1% with sutures removed late, and 70.2% with sutures in place. For all eyes, the mean spherical equivalent at last follow-up was -2.50 D, with 75% of eyes falling between -4 and +2 D. The mean final refractive error was -3.40 +/- 3.53 D for eyes with sutures removed early and -1.79 +/- 3.99 D for eyes with sutures removed late. Eyes with sutures remaining had a mean final refractive error of -0.33 +/- 2.25 D. There was an overall decrease in refractive and keratometric astigmatism after both early and late suture removal with no significant difference between groups. However, there was a wide range of change with some eyes experiencing a decrease and others an increase in astigmatism. Mean postoperative K readings increased significantly for both groups after suture removal (final mean K, 47.00 D) but remained stable for eyes with sutures in. CONCLUSION: The authors data suggest that the final refractive error and net change in refractive and keratometric astigmatism after the triple procedure are not dependent on the timing of suture removal.     

Hormonal treatment of breast cancer. Implications for quality of life, communication and improved therapy]

OBJECTIVE: The study was designed to improve the safety and predictability of radial keratotomy (RK). METHOD: Penetrating keratoplasty was performed on two eyes following RK for 2 months and 2 years respectively and their corneal buttons were studied histopathologically. RESULTS: The study revealed that at 2 months, there was only bridge-like healing of corneal epithelium, and oblique "V"-shaped, discontinuous or shallow incisions were seen, at 2 years, the healing process of partial incisions had not completed, and epithelial emboli were seen in the deep part of some incisions. CONCLUSION: Postoperatively, the incisions of RK are unstable for quite a long time. The RK incisions may influence other corneal surgeries performed on the same cornea in the future and are directly related to the healing and refractive outcome of RK. It is important to standardize the operative techniques.     

A multicenter trial of photorefractive keratectomy for residual myopia after previous ocular surgery. Summit Therapeutic Refractive Study Group

PURPOSE: The Summit Therapeutic Refractive Clinical Trial is a nine-center prospective, nonrandomized, self-controlled trial to assess the efficacy, stability, and safety of using a standardized technique of excimer laser photorefractive keratectomy (PRK) to correct residual myopia in eyes with previous refractive surgery or cataract surgery. PATIENTS AND METHODS: Eligible eyes with a mean residual myopia of -3.7 +/- 1.8 diopters (D) (range, -0.63 to -11.00 D) underwent PRK with a 193-nm excimer laser for myopic corrections between -1.50 and -7.50 D. Standardized settings were used for the ablation zone, ablation rate, repetition rate, and fluence. One hundred seven of the first 114 treated eyes were examined 1 year after PRK, with 98% of eyes having had refractive keratotomy and 2% having had cataract surgery. RESULTS: One year postoperatively, the mean manifest spherical equivalent refraction was -0.6 +/- 1.4 D (range, -6.50 to 2.50 D); 63% of eyes were within +/-1.00 D of the attempted correction; and uncorrected visual acuity was 20/40 or better in 74% of eyes. Twenty-nine percent of eyes lost two or more Snellen lines of best-corrected visual acuity, and central corneal haze was moderate or severe in 8% of eyes. CONCLUSIONS: Excimer laser PRK is effective in reducing residual myopia after previous refractive and cataract surgery. However, it is less accurate than PRK in eyes that did not undergo surgery and is more likely to cause a loss of best-corrected visual acuity 1 year after treatment.     

A prospective clinical study of correction of myopic astigmatism by combined treatment with PRK and T-incision and photoastigmatic refractive keratectomy. The results after one year

BACKGROUND: In contrast to the correction of simple myopia there is no widely accepted technique for the correction of myopic astigmatism. Currently two techniques are available: the photoastigmatic refractive keratectomy (PARK) and the combination of arcuate keratotomies with standard PRK (PRK-T). METHODS: In two groups, 67 patients underwent a correction of myopic astigmatism in a total of 87 eyes (19 by PRK-T and 68 by PARK), and were followed for 1 year. The spherical equivalent was -6.7 D in both groups and the refractive astigmatism ranged from -1.0 to -6.5 D. The PARK procedure was performed by means of an elliptic ablation (Kertom I, Schwind) with a 5.8 x 8.1 mm zone. The PRK-T technique consisted of two arcuate keratotomies with a free optical zone of 7 mm and a standard myopic PRK at least 6 weeks later. RESULTS: The 1 year follow-up was completed in 57 out of 87 eyes included in the study. At 1 year post-operation, 83% of the PRK-T group and 80% of the PARK group had an uncorrected visual acuity of 20/40 or better. The refractive astigmatism was reduced by 76% in the PRK-T group and by 67% in the PARK group. The spherical equivalent was -0.59 +/- 1.1 D at 1 year after PRK-T and -0.28 +/- 1.04 D after PARK. In three eyes of the PARK group (6.7%) a visual loss of more than one Snellen line occurred. Two of these eyes had a preoperative myopia of more than -6 diopters. CONCLUSION: Both techniques have the potential to reduce myopic astigmatism, however, the success rate is not as high compared to spherical PRK. Also, the complication rate of 2.5% in corrections to -6 D is significantly higher than that with spherical myopic PRK.     

New results using Laue diffraction and time-resolved crystallography

PURPOSE: To determine the antiproliferative effect of minoxidil on human corneal epithelium (hCE) proliferation in vitro and to assess whether topical minoxidil can significantly alter corneal topography after radial keratotomy (RK) by inhibiting myofibroblast activity in the keratotomy wound. SETTING: Corneal Research Laboratory, University of Chicago, Illinois, USA. METHODS: In the in vitro evaluation, proliferating hCE was exposed to minoxidil (0.1 to 2.0 mM) for 96 hours to determine the minimum inhibitory dose. Human corneal epithelium cell proliferation was assessed by the incorporation of bromodeoxyuridine (BRDU) into DNA. In the in vivo analysis, eight New Zealand albino rabbits had an eight-incision bidirectional RK on one eye and were divided into two groups. The control eyes (n = 3) received tobramycin and dexamethasone (TobraDex), ciprofloxacin hydrochloride (Ciloxan), and balanced salt solution (BSS) drops four times a day for 3 weeks, while the treatment eyes (n = 5) received TobraDex, Ciloxan, and minoxidil 1.0 mM drops four times daily for 3 weeks. The net change in corneal curvature at 3 weeks was analyzed with corneal topography. Myofibroblast activity in the keratotomy wound was assessed using alpha smooth muscle actin staining techniques. RESULTS: At concentrations of 1.0 mM and above, minoxidil caused a statistically significant, dose-dependent reduction in hCE cellular proliferation ranging from 29 to 44% (P < .05). Minoxidil (1.0 mM) caused a statistically significant central corneal flattening effect of 4.66 diopters (D) after RK in the treatment eyes compared with 1.11 D in the control eyes (P = .05). Histologically, minoxidil-treated keratotomy wounds lacked cells with contractile elements consistent with myofibroblast differentiation. Corneal epithelial wound healing was similar in both groups. CONCLUSION: At the appropriate dose, topical minoxidil may be a useful adjunctive treatment that can reduce the number of undercorrections after mini-RK without apparent toxicity to the corneal epithelium.     

Photorefractive keratectomy for astigmatism greater than -2.00 diopters in eyes with low, high, or extreme myopia

PURPOSE: To assess the efficacy of excimer laser photorefractive astigmatic keratectomy (PARK) in correcting astigmatism of more than -2.00 diopters (D) in eyes with low, high, and extreme myopia. SETTING: Pusan National University Hospital, Pusan, Korea. METHODS: Eighty-five patients (110 eyes) whose spherical error ranged from -3.00 to -13.00 D and cylinder ranged from -2.00 to -5.50 D had PARK with a VISX Twenty-Twenty excimer laser; follow-up was 6 months. All cases of myopic astigmatism were treated using the elliptical method and multizone ablation technique. Eyes were divided into 3 groups: low myopia, less than 6.00 D (n = 47); high myopia, from 6.25 to 10.00 D (n = 43); extreme myopia, over 10.25 D (n = 20). Alpins vector analysis was used to calculate the astigmatic change. RESULTS: By vector analysis, the success rate of astigmatic correction was more predictable in the low and high myopia groups than in the extreme myopia group (P < .05). There was little improvement in astigmatism in the extreme myopia group. CONCLUSION: Using PARK to correct astigmatism greater than -2.00 D in eyes with myopia less than -10.00 D tended to result in undercorrection; astigmatic correction in eyes with myopia over 10.25 D was minimal.     

The assistant's guide to radial keratotomy

1. The role of the ophthalmic assistant in radial keratotomy (RK) patient care involves three basic areas: patient preparation, suite preparation, and RK day. Complications as well as pros and cons of RK are covered. 2. A truly informed consent to RK must be achieved. 3. The key to managing refractive patients is preparation and organization. Every technician working with RK patients should know every detail of the RK practice. The patients must be prepared as well; there should be no real surprises during the postoperative course.     

Retrephination keratoplasty for high astigmatism after penetrating keratoplasty

PURPOSE: We report preliminary results of a new procedure for correcting high astigmatism after penetrating keratoplasty. METHODS: The procedure entails full-thickness trephination along the original donor-recipient junction with careful suturing in a combined interrupted and running fashion. Four eyes of four patients with severe astigmatism and myopia after penetrating keratoplasty underwent the procedure. RESULTS: High preoperative cylinder ranging from 4.50 to 16.00 D (mean 9.00 D) was reduced to 0.50 to 3.50 D (mean 1.90 D) at the last examination (between 3 to 6 months). Spherical equivalent myopia ranging from -2.00 to -10.25 D (mean -4.90 D) was essentially unchanged at plano to -9.00 D (-4.70 D) at the last examination. Overall, there was a mean refractive cylinder reduction of 7.10 D (79%). CONCLUSION: Retrephination after penetrating keratoplasty appears to be an acceptable alternative for correcting high astigmatism, and had only a small effect on the level of myopia.     

Retrospective comparison of photorefractive keratectomy and radial keratotomy

BACKGROUND: The efficacy and predictability of photorefractive keratectomy and radial keratotomy become increasingly relevant. This retrospective study compares one surgeon's experience with photorefractive keratectomy and radial keratotomy over a 3-year period from 1990 to 1993. METHODS: Photorefractive keratectomy was performed on 103 eyes of 76 patients that met the inclusion criteria for the phase IIb, phase III, and phototherapeutic keratectomy studies as delineated by the United States Food and Drug Administration. Radial keratotomy was performed on 117 eyes of 81 patients with up to 9.00 diopters (D) of myopia. RESULTS: In the photorefractive keratectomy group, 83% of the eyes achieved uncorrected visual acuity of at least 20/40; 37% saw 20/20; 88% had a refraction within 1.00 D of emmetropia, and 63% within 0.50 D of emmetropia. For the radial keratotomy group, 85% of the eyes achieved an uncorrected visual acuity of 20/40 or better; 27% saw 20/20; 88% had a refraction within 1.00 D of emmetropia; and 55% within 0.50 D of emmetropia. There were no serious complications, and only one single eye in each of the photorefractive keratectomy and radial keratotomy groups lost two lines or more of spectacle-corrected visual acuity. CONCLUSION: Photorefractive keratectomy and radial keratotomy are both effective procedures, and result in similar refractive outcomes for myopia of -1.00 to -9.00 D.     

Treatment of myopic astigmatism with the Summit Apex Plus excimer laser

PURPOSE: To assess the results of surface sequential toric photorefractive keratectomy (PRK) with the Summit Apex Plus excimer laser using an erodible mask. METHODS: A prospective study was performed on consecutive eyes having surface sequential toric PRK over a 4 month treatment period. Attempted astigmatism correction varied from 70 to 100%, depending on the power and axis of the cylinder. The myopic correction was adjusted so the combined treatment aim was emmetropia. Refraction, manual keratometry, corneal haze, and visual acuity data from preoperative and follow-up visits over 12 months were divided into various groups based on the preoperative refraction and analyzed. RESULTS: Fifty-nine eyes from 48 patients had sequential toric PRK. Preoperatively, the mean spherical equivalent at glasses plane (SEGP) was -4.88 diopters (D) +/- 3.20 (SD) and the mean refractive cylinder, 2.02 +/- 1.04 D. The mean attempted cylinder correction was 1.87 D. At 12 months the mean SEGP was -0.02 +/- 0.67 D, which was not statistically significant from plano. The mean refractive cylinder was 0.84 +/- 0.84 D, which was statistically significantly different from zero cylinder power. There was a statistically significant correlation between the preoperative and the 12 month postoperative refractive cylinder powers. At 12 months, 34 of 43 eyes (79.1%) had an uncorrected visual acuity of 6/12 or better. While 2 eyes in one patient (4.7%) lost two lines of best corrected visual acuity, with a final acuity of 6/12 in each, no patient lost more than two lines. CONCLUSION: The manifest refraction cylinder power is not fully corrected with the current treatment algorithms; however, surface sequential toric PRK using an erodible mask is capable of treating compound myopic astigmatism with moderate success.