Moderate Astigmatism Research Articles

Correction of Astigmatism During Cataract Surgery: Toric Intraocular Lens Compared to Peripheral Corneal Relaxing Incisions

To compare the efficacy of astigmatic correction achieved at the time of cataract surgery using toric intraocular lens (IOL) implantation versus peripheral corneal relaxing incisions. A retrospective review assessed the outcomes of phacoemulsification cataract surgery performed between January 2006 and January 2008 by a single surgeon. Patients receiving a toric IOL (toric IOL group) or peripheral corneal relaxing incisions (relaxing incisions group) were included in the study. Main outcome variables included postoperative uncorrected distance visual acuity (UDVA) and manifest refractive cylinder. Each treatment modality was stratified by amount of preoperative keratometric astigmatism into three groups (low, moderate, and high astigmatism) for comparative analysis. A total of 192 eyes were included in the study; 77 received a toric IOL and 115 received peripheral corneal relaxing incisions. Preoperative data were not significantly different between the two groups except regarding keratometric astigmatism, which was higher in the toric IOL group (P<.05). Average postoperative astigmatism was 0.42 diopters (D) and 0.46 D in the toric and relaxing incisions groups, respectively. In subgroup analysis, no statistical significance separated the two treatment options in terms of amount of surgically induced astigmatism or residual astigmatism. Eyes with astigmatism ≥2.26 D were more likely to achieve 20/40 UDVA from a toric IOL. Toric IOL implantation and peripheral corneal relaxing incisions yielded similar results regarding surgical correction of astigmatism at the time of phacoemulsification cataract surgery. Both treatment modalities achieved comparable results with mild-to-moderate astigmatism. Higher degrees of astigmatism favor use of a toric IOL.

Interface Haze Formation After Ultra Thin Flap Laser in Situ Keratomileusis.

In this case series, five patients (10 eyes) underwent laser in siter keratomileusis (LASIK) for the correction of moderate myopia and astigmatism with the Schwind Carriazo Pendular microkeratome 90 mum head. Flap (superior hinged) thickness measured intraoperatively was assessed less than 70 mum in all eyes. On first month's postoperative examination, subepithelial mild corneal haze with consequent myopic regression was found in all patients. A significant improvement of haze formation and residual refractive error were observed during the following postoperative months. In conclusion, post-LASIK subepithelial corneal haze after thin flap creation is a temporarily potential complication that could affect patient's refractive error during the first postoperative month.

Microincision cataract surgery with toric intraocular lens implantation for correcting moderate and high astigmatism: Pilot study

To evaluate the results of microincision cataract surgery (MICS) with toric intraocular lens (IOL) implantation to correct moderate to high astigmatism in patients with cataract. Vissum-Instituto Oftalmológico de Alicante, Alicante, Spain. This prospective nonrandomized study comprised patients with visually significant cataract and moderate to high astigmatism (>2.00 diopters [D]). After MICS, an Acri.Comfort 646 TLC toric IOL was implanted in the capsular bag. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, residual refractive sphere, residual refractive and keratometric cylinders, and IOL axis alignment were measured after 3 months. Vector analysis of astigmatism was by the Alpins method. The study included 21 eyes (12 patients). The UDVA was 20/40 or better in 16 eyes (76.1%), and the CDVA was 20/30 or better in 18 eyes (85.7%). The mean refractive cylinder decreased significantly after surgery, from -4.46 D +/- 2.23 (SD) to -0.45 +/- 0.63 D (P<.05). Astigmatism analysis by vectors showed a mean surgically induced astigmatism vector of 0.99 x 1 degrees and a mean difference vector of 0.23 x 8 degrees. The mean index of success was 0.11 +/- 0.15. Ninety-one percent of astigmatism was corrected. The mean IOL axis rotation was -1.75 +/- 2.93 degrees; the rotation was 10 degrees or less in all eyes. No complications occurred. Implantation of a toric IOL after MICS was a safe, precise, and effective procedure to correct moderate to high astigmatism in cataract patients. No author has a financial or proprietary interest in any material or method mentioned.

One-month Outcomes of Wavefront-guided LASIK for Low to Moderate Myopia With the VISX STAR S4 Laser in 32,569 Eyes

To determine the safety and efficacy of wavefront-guided LASIK for the correction of low to moderate myopia, as performed by surgeons employed by Optical Express, a large corporate provider. Data were extracted from the Optical Express central database on 22,900 patients (42,143 eyes) who underwent primary LASIK to treat low to moderate myopia and/or astigmatism. All treatments used a wavefront-guided ablation profile and had a refractive target of emmetropia. Outcomes were evaluated using 1-month follow-up data, which were available for 32,569 eyes of 17,713 patients (77% follow-up). Complications were tabulated using all available data. The mean manifest spherical equivalent (MSE) was reduced from -2.97 +/- 1.33 diopters (D) (range: -0.37 to -6.00 D) to -0.03 +/- 0.29 D (range: -3.50 to +4.50 D) 1 month after surgery. Ninety-four percent of eyes were within 0.50 D of the intended correction, and the correlation coefficient of the attempted versus achieved MSE was 0.96. Uncorrected visual acuity (UCVA) of 20/20 or better was achieved in 92% of eyes; 99% of eyes achieved UCVA of 20/40 or better. Among patients who had bilateral laser vision correction, 98% achieved 20/20 uncorrected binocular vision. Average best spectacle-corrected visual acuity (BSCVA) improved slightly 1 month after surgery (mean change: +0.01 logMAR). There were 210 (0.67%) eyes that lost 2 or more lines of BSCVA; however, all eyes were 20/40 or better. Intraoperative complications occurred in 25 eyes (0.06%; 1:1686), and postoperative complications occurred in 210 eyes (0.64%; 1:155). The most common complications were dry eye (n=58; 0.18%; 1:562) and mild diffuse lamellar keratitis (grade 1 or 2) (n=58; 0.18%; 1:562). Wavefront-guided LASIK can safely and effectively correct low to moderate myopia, as demonstrated by 1-month postoperative visual outcomes from a large number of patients.

Three Cases of Corneal Tattooing for the Treatment of Traumatic Iris Defect

Purpose: To investigate the effects of corneal tattooing on patients with a traumatic iris defect. Case Summary: Corneal tattooing operation was performed on three patients (3 cases) with a traumatic iris defect. In case 1, the cornea was dyed with Davidson marking dyes (Bradley Products Inc., MN, US) and the amniotic membrane with the central incision was permanently transplanted. In case 2, both corneal dyeing and permanent amniotic membrane transplantation were performed on the area of partial iris loss. In case 3, corneal dyeing was performed after the intrastromal cornea was dissected. Corneal reepithelization was found in the first 2 cases 12 and 9 days after amniotic membrane transplantation, respectively. Three months after the transplantation, all three cases showed an improvement in best corrected visual acuity (BCVA), with an increase of one or more lines on the Snellen Chart. Simultaneously, preoperative monocular contrast and glare were also found to beimproved in all three cases. In both cases 1 and 2, 60% of the initially used dyes still remained in the cornea 6 months after the surgery, and in case 3, 90% of the initial dye remained. Except for the moderate astigmatism found earlier after the surgery in case 3, no serious complications developed. Conclusions: Corneal tattooing can improve the visual acuity and reduce glare in eyes with a traumatic iris defect and is cosmetically pleasing. Furthermore, corneal tattooing can be performed more easily and repeatedly than black diaphragm intraocular lens implantation.

Laser-assisted intrastromal keratomileusis in a patient with systemic mastocytosis

Background The U.S. Food and Drug Administration (FDA), and more recently the American Academy of Ophthalmology (AAO), list relative and absolute contraindications to laser-assisted intrastromal keratomileusis (LASIK). The AAO guidelines consider connective tissue or autoimmune diseases and systemic immunosuppresion as relative contraindications and only uncontrolled diseases and uncontrolled ocular allergy as absolute contraindications. Recent reports concluded that LASIK could be performed effectively and safely in selected patients with stable and controlled systemic diseases. Reported here is a case of successful LASIK with 3 years℉ follow-up in the setting of systemic mastocytosis. Case report A 42-year-old woman with moderate myopia and astigmatism underwent bilateral LASIK. Her medical history was significant for systemic mastocytosis. Five days after surgery, a diffuse lamellar keratopathy (DLK) 1+ was observed in the left eye and treated successfully with prednisolone acetate. The patient achieved visual acuity of 20/20 in each eye unaided. These findings were stable at 7, 12, 18, and 36 months after surgery. She continues to use olopatadine. Conclusion Because of the rare nature of systemic mastocytosis and the anaphalactoid mechanism of release of mast cells, it may be difficult to assess the risk of undergoing LASIK. Any known or suspected triggers must be avoided. The use of an antihistamine and mast cell stabilizer, as used in this case, may have a beneficial effect.

Results of Penetrating Keratoplasty Performed with a Femtosecond Laser Zigzag Incision Initial Report

To determine the initial outcomes of utilizing a femtosecond laser to perform penetrating keratoplasty incisions in a zigzag pattern. Retrospective consecutive surgical series. Patients undergoing full-thickness corneal transplant surgery in a referral academic practice. The IntraLase femtosecond laser performed matching donor and host zigzag incisions in a consistent pattern in 13 eyes of 13 patients. Topographically determined astigmatism, imaging of incisions by anterior segment optical coherence tomography, and best spectacle-corrected visual acuity (BSCVA). Postoperative follow-up ranged from 3 to 9 months. Mean astigmatism was < or =3.0 diopters (D) at all intervals beginning at 1 month postoperatively. Maximum astigmatism was 4.25 D from month 3 onward. Nine eyes (69%) had < or =3 D and 6 eyes (46%) had < or =2 D by month 3. In the 8 eyes with full vision potential, 7 (87.5%) had BSCVA> or =20/30 by month 3; the eighth eye had improved to 20/25 by month 6. Optical coherence tomography images showed excellent anterior and posterior wound alignment, including one eye where the running suture loosened and was fully removed before month 3. The femtosecond laser-generated zigzag incision is biomechanically stable, resulting in excellent wound apposition, wound integrity with minimal suture tension, and recovery of good levels of BSCVA with moderate astigmatism within months of surgery.

Conductive keratoplasty

Conductive keratoplasty is a noninvasive, in-office procedure for the correction of hyperopia, hyperopic astigmatism, and management of presbyopia. It serves as an alternative to laser-based refractive surgery with essentially no intraoperative or postoperative complications. In the past decade, photorefractive keratectomy and laser in-situ keratomileusis have been the most popular refractive surgical procedures to correct myopia, hyperopia and astigmatism. Although relatively safe, flap-related complications often result in undesirable visual acuity. Since US Food and Drugs Administration approval in 2002, conductive keratoplasty has become a promising technique to correct low to moderate hyperopia and astigmatism. The procedure was first used by Mendez and colleagues in 1993. It is a nonlaser, no cutting procedure that delivers radio-frequency energy to corneal stroma in a circular fashion to steepen the cornea. Multiple studies have shown that conductive keratoplasty offers equal or superior efficacy, predictability, stability and safety than currently used refractive procedures to correct hyperopia or hyperopic astigmatism. In addition, monovision conductive keratoplasty has been shown to be successful for the management of presbyopia. Conductive keratoplasty, an alternative to the laser-based procedure, is effective, predictable, and safe to correct low to moderate hyperopia, astigmatism, and manage presbyopia.

Safety, efficacy, and stability indices of LASEK correction in moderate myopia and astigmatism

Purpose: To evaluate the visual outcomes and complications in low to moderate levels of myopia and astigmatism treated with laser-assisted subepithelial keratectomy (LASEK) with a focus on postoperative recovery. Setting: Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA. Methods: A retrospective analysis of a case series of eyes treated with LASEK from 1996 to July 2002 with a follow-up of 2 years was performed. The LASEK technique involved creating an epithelial flap with 25 to 45 seconds of exposure to 20% alcohol, ablating the corneal surface using 3 different excimer lasers and nomogram adjustment, and repositioning the flap and applying a bandage contact lens. The main outcome measures were uncorrected visual acuity (UCVA), efficacy index, manifest refraction, best spectacle-corrected visual acuity (BSCVA), safety index, retreatment rate, and complications. Results: One hundred seventy-one eyes (85 right eyes and 86 left eyes) of 105 patients were studied. Preoperatively, the mean spherical equivalent was −2.99 diopters (D) ± 1.43 (SD) (range −0.38 to −7.75 D) and the mean cylinder, −0.78 ± 0.73 D. The UCVA ranged from 20/800 to 20/32, and the BSCVA ranged from 20/63 to 20/16; the median was 20/20. One week postoperatively, 96% of eyes had a UCVA of 20/40 or better but definitive visual recovery took more than 4 weeks in some eyes. Approximately 95% of eyes were within ±1.0 D of emmetropia after 4 to 52 weeks; the remaining 5% did not show major deviations. At 4 to 52 weeks, only 1 eye was overcorrected by more than 1.0 D of manifest refraction. The safety index remained close to 1.0 for the follow-up after 4 weeks. The efficacy index displayed a plateau at 0.9 from 1 month to 1 year. No serious complication (including recurrent erosion syndrome) was encountered. The mean follow-up was 31 weeks, and the retreatment rate was 2.9% up to 2 years of follow-up. Conclusions: The long-term safety and effectiveness of LASEK for the correction of low to moderate myopia and astigmatism were demonstrated. The treatment effect stabilized after 4 weeks.

Advances in phakic intraocular lenses: indications, efficacy, safety, and new designs.

The recent evolution of phakic intraocular lenses (PIOLs) has made this refractive surgical technique safer, very predictable, and effective. Due to these reasons, PIOLs have been expanding the horizon of their indications. The aim of this review is to update the reader in the recent advances reported on the topic during the year 2003. The most recent progress has been made towards decreasing the incision size down to 3 mm or less for all PIOLs models to avoid pupil ovalling in angle-supported designs with new biomaterials or exchangeable haptics, and to decrease the incidence of cataract induction in posterior chamber models with modified designs and better sizing. High-order aberrations and the quality of vision are improved with PIOLs. The main limitation for the further development of PIOLs is the lack of adequate diagnostic imaging techniques to perform a precise preoperative study of the anterior segment anatomy. Emerging diagnostic technologies based on the use of very high frequency (100 MHz) ultrasound and optical coherence tomography seem to have a most important role in the future development of PIOLs defining preoperatively the most adequate anatomic conditions for each design. PIOLs offer today an excellent alternative for the correction of high and moderate myopia, hyperopia, and astigmatism. Emerging indications, still under investigation, include presbyopia and pediatric anisometropic amblyopia. Due to their advantages for quality of vision and the increased knowledge on their safety, as well as the evidence of their predictability, PIOLs are expected to largely increase their clinical use as a refractive surgical technique in the coming years.

Diode laser thermal keratoplasty for hyperopia and hyperopic astigmatism in patients younger than 40 years.

We performed a prospective, nonrandomized investigation of contact continuous wave diode laser thermal keratoplasty (DTK) for correction of hyperopia and hyperopic astigmatism. The goal of surgery was not to achieve emmetropia but to investigate the refractive effect in patients younger than 40 years. Twenty eyes with spherical hyperopia (Group A) and 15 eyes with hyperopic astigmatism (Group B) were treated with two rings; treatment zone diameter of the inner ring was 6 or 7 mm. Each ring consisted of eight spots for hyperopia correction; for astigmatism correction four additional pairs of spots were applied around the flat corneal meridian. Mean change in manifest spherical equivalent refraction 18 months postoperatively in Group A was 2.00 +/- 0.90 D (Group B, 15 mo, 1.80 +/- 0.60 D). Mean increase in keratometric power was 1.20 +/- 0.60 D (1.30 +/- 0.60 D). Mean refractive astigmatism reduction was 0.10 D (1.70 D). Mean paired differences per month for regression between spherical equivalent manifest refraction/keratometric power was 0.12/0.04 D (0.06/0.05 D) from 9 to 12 months, 0.01/0.04 D (0.06/0.06 D) from 12 to 15 mo, and -0.03/ +/- 0 D from 15 to 18 months. Mean uncorrected visual acuity improved from 20/100 to 20/32 (20/63 to 20/32). No eye lost more than 1 line of BSCVA. The amount of correction showed an age dependency. DTK is a minimally invasive, low-risk procedure, and was effective for correction of low hyperopia and low to moderate hyperopic astigmatism in patients less than 40 years.

Subjective and objective assessments of the effect of orthokeratology – A cross-sectional study

Purpose. To determine which clinical tests are useful in orthokeratology aftercare examination, and to examine the objective and subjective characteristics of a group of orthokeratology lens wearers. Methods. Thirty orthokeratology subjects (8–19 years) who had been wearing orthokeratology lenses for over 12 months were recruited. Autorefraction, corneal topography, retinoscopy, subjective refraction and biomicroscopy were performed. Only left eyes results were analysed. Subjective ratings of symptoms and problems experienced by subjects were obtained using a questionnaire. Results. Autorefraction yielded higher residual sphere and residual cylinder by –0.54 D and –0.39 D respectively while retinoscopy yielded higher residual sphere and residual cylinder by –0.20D and –0.03 D respectively. Corneal toricity measured by autokeratometry and corneal topography overpredicted the residual cylinder by –2.02D and –2.08D respectively. The mean ± SD residual spherical equivalent refractive error was –0.11 ± 0.57 D and the mean ± SD unaided postorthokeratology visual acuity was 0.08 ± 0.14 logMAR. The unaided visual acuity was significantly related to the residual cylinder. Pigmented arc was present in 16 corneas (53%). The most common problems/symptoms experienced by the subjects were lens binding (73%), ocular discharge in the morning (69%) and blur distance vision (47%). Over 80% of the subjects found lens handling troublesome in varying degree. All, except two subjects (who disliked the lens handling), wanted to continue the treatment. Conclusions. History taking, subjective refraction, biomicroscopy and corneal topography are important in a routine orthokeratology aftercare examination. Corneal pigmented arc, ocular discharge in the morning and lens binding were the most common sign, symptom and problem respectively observed/ reported. Most orthokeratology lens wearers with low to moderate myopia and low astigmatism enjoyed reasonably good unaided post-orthokeratology vision in the daytime.

Pupil size and quality of vision after LASIK

Purpose To evaluate factors related to the quality of vision after LASIK. Design Survey study. Participants One hundred consecutive patients. Intervention LASIK with a 6.0-mm elliptical ablation pattern without transition zone to treat mild to moderate myopia or astigmatism (preoperative manifest spherical equivalent [MSE], −4.79 ± 1.33 diopters [D]; range, −2.88 to −9.25 D). The second eye was treated 1 month after the first. Main outcome measures Completed questionnaires assessing night vision problems (glare, haze, and halo symptoms) before surgery and at 1, 3, and 6 months after surgery in 97, 75, 81, and 66 subjects, respectively. Mesopic pupil size and preoperative and postoperative variables were analyzed with questionnaire data using an analysis of variance (ANOVA) and multivariate regression analysis. Results Patients with large mesopic pupils had significantly more reports of glare, haze, and halo than did those with smaller pupils in the treated eye at 1 month after surgery ( P=0.02, P=0.03, and P=0.02, respectively ANOVA) and of glare at 3 months ( P=0.05). Significant predictors of symptoms at 6 months, identified through multivariate regression analysis, included preoperative MSE (for glare and haze), preoperative contrast acuity (glare), postoperative uncorrected visual acuity (UCVA; haze), and residual cylinder (haze). Together, these factors accounted for only 19% of the overall variability in glare and 37% of the variability in haze responses. No relationship between pupils and symptoms was noted at 6 months after surgery in either the ANOVA or regression analysis group. Conclusions Patients with large pupils had more quality of vision symptoms in the early postoperative period, but no correlation was observed 6 months after surgery. Factors related to long-term symptoms include the level of treatment (preoperative myopia), preoperative contrast acuity, postoperative UCVA, and residual cylinder. Most of the variability in visual quality could not be explained by preoperative or clinical outcome measures, including pupil size.

Loss of vision after laser in situ keratomileusis.

To research the incidence of visual loss after laser in situ keratomileusis (LASIK). We reviewed an extensive review of the literature published by The Ophthalmic Technology Assessment Committee of the American Academy of Ophthalmology regarding the safety and efficacy of LASIK. We also reviewed other recent literature. For low to moderate myopia and astigmatism, LASIK is efficient, safe, and predictable with few eyes losing two or more lines of best-corrected visual acuity (BCVA). For moderate to high myopia, the results are more variable and more eyes lost two or more lines BCVA. In both cases, this BCVA occurred in studies published on or before 1999. Serious adverse complications leading to significant visual loss are probably rare. Continued development of microkeratomes and laser technology are continuing to reduce the rare complications that do occur and improve functional outcomes and patient satisfaction.

Treating astigmatism at the time of cataract surgery.

Correcting astigmatism at the time of cataract surgery can be accomplished either by incisional techniques, such as use of a cataract incision for flattening or astigmatic keratotomy, or by implanting a toric intraocular lens. Both methods can reduce mild to moderate astigmatism. For correcting larger amounts of astigmatism, a combination of techniques can produce greater correction. New methods of analyzing the change induced by surgery provide a more complete understanding of the astigmatic change.

200 Hz flying-spot technology of the LaserSight LSX excimer laser in the treatment of myopic astigmatism: six and 12 month outcomes of laser in situ keratomileusis and photorefractive keratectomy

Purpose: To evaluate safety, efficacy, predictability, and stability in the treatment of myopic astigmatism with laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) using the 200 Hz flying-spot technology of the LaserSight LSX excimer laser. Setting: SynsLaser Clinic, Tromsø, Norway. Methods: This retrospective study included 110 eyes treated with LASIK and 87 eyes treated with PRK that were available for evaluation at 6 and 12 months, respectively. The mean preoperative spherical equivalent (SE) was −5.35 diopters (D) ± 2.50 (SD) (range −1.13 to −11.88 D) in the LASIK eyes and −4.72 ± 2.82 D (range −1.00 to −15.50 D) in the PRK eyes. The treated cylinder was 4.00 D in both groups. Eleven (8.5%) LASIK eyes and 8 (7.4%) PRK eyes had secondary surgical procedures before 6 and 12 months, respectively, and were excluded when the 6 and 12 month outcomes were analyzed. Results: None of the eyes lost 2 or more lines of best spectacle-corrected visual acuity. Seventy-seven percent of the LASIK eyes and 78% of the PRK eyes achieved an uncorrected visual acuity of 20/20 or better; 98% in both groups achieved 20/40 or better. The SE was within ±0.5 D of the desired refraction in 83% of the LASIK eyes and 77% of the PRK eyes; it was within ±1.0 D in 97% and 98%, respectively. The cylinder correction had a mean magnitude of error of 0.04 ± 0.31 D (range −0.96 to +0.85 D) in the LASIK eyes and 0.02 ± 0.37 D (range −1.44 to +0.72 D) in the PRK eyes. Refractive stability was achieved at 1 month and beyond in the LASIK eyes and at 3 months and beyond in the PRK eyes. Conclusion: The outcomes of this study are comparable to those achieved with lasers that use small-beam technology with a lower frequency, as well as with other types of delivery systems. They suggest that the 200 Hz technology used in the LaserSight LSX excimer laser is safe, effective, and predictable and that with LASIK and PRK the results are stable when treating low to moderate myopia and astigmatism up to 4.0 D.

Postoperative complications in laser in situ keratomileusis.

Laser in situ keratomileusis (LASIK) has become the most common procedure to correct refractive errors in North America. Increasing numbers of patients and surgeons are choosing LASIK in the management of low and moderate myopia, astigmatism, and hyperopia. LASIK presents a unique group of postoperative challenges and complications. It is important to be able to identify these complications in the early and late postoperative periods and to provide effective management. In this article, we review the most commonly encountered early and late postoperative complications after LASIK and the most current methods in prevention and treatment.

Photoastigmatic Refractive Keratectomy or Laser in situ Keratomileusis for Moderate and High Myopic Astigmatism

To compare the efficacy and safety of laser in situ keratomileusis (LASIK) and photoastigmatic refractive keratectomy (PARK) to treat moderate and higher myopic astigmatism. A retrospective nonrandomized study of 78 eyes with myopic astigmatism (range, 2.00 to 6.00 D) was undertaken. Thirty-eight eyes were treated with LASDK and 40 eyes were treated with PARK. Groups were similar in terms of baseline sphere and refraction. Photoablation for both LASDX and PARK was performed by single pass for correction of -6.00 D or less spherical equivalent refraction or multi-pass, multi-zone at 4, 5, and 6 mm for corrections greater than -6.00 D. Astigmatism was corrected using a single-pass ablation at 6.0 mm diameter. Visual acuity, manifest refraction, corneal topography, and patient satisfaction were measured preoperatively and postoperatively. Six months postoperatively, uncorrected visual acuity was 20/40 or better in 100% of LASEK eyes and 90.0% of PARK eyes; 20/25 in 86.84% LASEK eyes and 47.5% of PARK eyes; 20/20 in 65.75% of LASEK eyes and 15% of PARK eyes. Postoperative residual cylinder was -0.54 ± 0.32 D in LASEK eyes and -1.28 ± 0.80 D in PARK eyes. Postoperative residual cylinder axis remained stable (within 15° at 1 month postoperatively) in 61.1% of LASEK eyes and 40% of PARK eyes. In 5.3% of the LASEK eyes, corneal haze developed; 95.5% of PARK eyes developed corneal haze. One LASIK eye lost best spectacle-corrected visual acuity and 3 eyes (7.89%) had a cap complication. Three eyes (7.5%) lost 2 lines of spectacle-corrected visual acuity due to severe corneal haze. Among LASEK patients, 92.1% were highly satisfied and 62.5% of PARK patients were highly satisfied. For myopic astigmatism between 2.00 and 6.00 D, LASEK provided better accuracy, fewer complications, and higher patient satisfaction than PARK. PARK may achieve an incomplete cylindrical correction and may have a higher associated rist of loss of best spectacle-corrected visual acuity. [J Refract Surg 2000;16(suppl):S268-S271).

Combined astigmatic keratotomy with corneal valvular incision in the treatment of high surgical astigmatism

Astigmatic keratotomy is used conventionally to correct moderate surgical astigmatism. However, cases with very high surgical astigmatism due to wound compression can show a dramatic response to relaxing keratotomies made in the steeper meridian. The effect obtained cannot be predicted pre-operatively by using standard nomograms. Coupled arcuate keratotomies combined with corneal valvular incisions were performed in a case of high astigmatism post-cataract surgery. Coupled arcuate keratotomies were combined with a corneal valvular incision enabled a surgical correction of nearly 9 D of astigmatism.

Excimer laser photoastigmatic refractive keratectomy: Eighteen-month follow-up

Objective To study the efficacy of photoastigmatic refractive keratectomy (PARK) by the MEL 60 (AesculapMeditec, Jana, Germany) scanning excimer laser for the treatment of myopic astigmatism, with follow-up of 18 months. Patients and methods One hundred and twenty-eight eyes of 102 patients with different degrees of myopic astigmatism were treated by PARK and followed prospectively in an open study. Ablations were performed with an MEL 60 excimer laser using an astigmatic module. Results Mean preoperative refractive cylinder improved from a preoperative value of −1.8 ± 0.8 diopters (D; range, −1.0 to −6.0 D) to −0.3 ± 0.5 D (range, +1.0 to −2.5 D) at 18 months. The mean reduction in cylindrical correction alone was 84 ± 37% in the low astigmatism group (−1.0 to −1.5 D); 91 ±21% in the moderate astigmatism group (−1.75 to −2.5 D); and 75 ± 25% in the high astigmatism group (−2.75 to −6.0 D). One hundred and three eyes (80%) at 12 months and 100 eyes (85%) at 18 months were within ±0.5 D of the intended astigmatic correction, with more eyes in the low astigmatic group. One hundred and nineteen eyes (93%) and 114 eyes (97%) at 12 and 18 months, respectively, were within ±1.0 D of the intended correction. Ninety-two percent to 95.7% of the eyes in the different groups had a postoperative axis less than 10 degrees of the preoperative and intended axis at 12 and 18 months after PARK. Uncorrected visual acuity (UCVA) of 20/40 or better was achieved in nearly 84% of the eyes 12 and 18 months after PARK. A UCVA of 20/20 was achieved in 49% of eyes 18 months after PARK. Ten eyes (8%) underwent reoperation at the end of 12 months. Conclusions The data indicate that PARK is an effective surgical tool for correcting astigmatism, especially astigmatism of 1.0 to −2.5 D, with a success rate of approximately 70%