Changes In Refractive Astigmatism Research Articles

Significant increase in astigmatism in children after study at home during the COVID-19 lockdown

ABSTRACTClinical relevanceEvaluating changes in refractive astigmatism after ‘study at home’ during the COVID pandemic may shed light on the aetiology of refractive errors.BackgroundTo investigate whether there has been a change in the proportion of astigmatism among primary school children after the school closure period during the COVID-19 pandemic.MethodsThis observational study compared cross-sectional (2018: n = 112; 2020: n = 173) and longitudinal data (n = 38) collected from two vision screenings, one in 2018 and the other after the school closure period in 2020, in the same primary school for children aged 8–10 years. Non-cycloplegic refraction and axial length were measured using an open‐field auto‐refractometer and IOL Master, respectively. A questionnaire focusing on demographic information, near-work time, and outdoor activities was administered to parents of all participants.ResultsWhile there were no significant differences in age, gender, or monthly family income between the two cohorts, astigmatism proportion (Cyl ≥ 0.75 D) in 2020 was 1.5-fold higher than that in 2018 (49.1% vs. 33.9%). The median cylindrical power was significantly higher in 2020 in older children (9 or 10 years old). More importantly, the children participating in both vision screenings had cylindrical power and J0 astigmatism significantly increased by 0.35 ± 0.40 D and 0.21 ± 0.25 D, respectively.ConclusionA significant increase in astigmatism (both proportion and magnitude) was found after the school closure period. Further studies are needed to investigate the origin of this increased astigmatism.

Changes in post-keratoplasty astigmatism after suture removal: refraction vs tomography vs aberrometry.

To analyse the changes in magnitude and orientation of astigmatism after suture removal (SR) in keratoplasty eyes as measured by refraction, tomography, and aberrometry. Twenty-six eyes of 25 patients after optical keratoplasty requiring SR to reduce the astigmatism during the follow-up period were prospectively included. Eyes with poor quality topography scans or if there were no sutures in the steepest semi meridian were excluded. Corrected distance visual acuity (CDVA), manifest refraction, corneal tomography and aberrometry were performed on all patients before and after SR. The mean age of the patients was 40.8±14.4y. Penetrating keratoplasty was performed in 23 eyes (89%) and deep anterior lamellar keratoplasty was done in 3 eyes (11%). There was a statistically significant reduction in the magnitude of refractive, tomographic and aberrometry astigmatism after SR (P<0.001) at 2h after suture removal. The mean net reduction of the astigmatism was greater as measured by corneal tomography compared to refractive astigmatism (P<0.05). There was no statistically significant change in refractive astigmatism between 2h and 2mo after SR (P=0.55). Vector calculations demonstrated a greater amount of undercorrection in the tomography group and the rotational error was more towards counterclockwise direction. Mean monocular logMAR CDVA improved from 0.57 D to 0.49 D after SR (P=0.002). The net reduction in the magnitude of astigmatism after SR is greater in the tomography and aberrometry groups. With one episode of SR, there is no difference in the aberration profile.

Best Indicators for Detecting Keratoconus Progression in Children: A Report From the Shahroud Schoolchildren Eye Cohort Study.

The purpose of this study was to investigate 3-year changes in keratoconus (KC) indices to determine the indicators of KC progression compared with age-related changes in children aged 6 to 12 years. In this report of the Shahroud Schoolchildren Eye Cohort Study, KC was diagnosed based on vision, refraction, tomography, and slitlamp examination findings. KC progression was defined as changes in refractive astigmatism or zonal maximum keratometry (Zonal Kmax-3 mm). Then, 3-year changes (Δ) in vision, refraction, and tomographic indices were compared between progressive KC and normal eyes. The best set of ∆parameters for distinguishing KC progression from age-related changes were determined using the area under curve (AUC). Eighteen KC eyes and 10,422 normal eyes were analyzed. All KC cases showed progression after 3 years. Δindices were statistically different between the 2 groups except corrected distance visual acuity, anterior radius of curvature, irregularity index, and KC percentage index. The best Δindices, in descending order of AUC value, were index of height decentration, Zonal Kmax-3 mm, refractive astigmatism, single point Kmax, and index of vertical asymmetry (all AUC > 0.9), followed by inferior-superior asymmetry, index of surface variance, minimum corneal thickness, index of height asymmetry, KC index, posterior radius of curvature, and Belin/Ambrósio total Deviation (AUC = 0.8-0.9). According to our findings, changes in index of height decentration, Zonal Kmax-3 mm, refractive astigmatism, single point Kmax, and index of vertical asymmetry are the best indices for detecting KC progression in children younger than 12 years.

The relationship between angle kappa and astigmatism after phacoemulsification with implanting of spherical and aspheric intraocular lens.

Purpose:To determine the significance of any association between either change in angle kappa (K°) or the rectilinear displacement (L, mm) of the first Purkinje image relative to the pupil center and unexpected changes in astigmatism after phacoemulsification.Methods:Orbscan II (Bausch and Lomb) measurements were taken at 1, 2, and 3 months after unremarkable phacoemulsification in patients implanted with spherical (group 1, SA60AT, Alcon) or aspheric (group 2, SN60WF, Alcon) nontoric IOLs. The outputs were used to calculate L. Astigmatism, measured by autorefractometry and subjective refraction, was subjected to vector analysis (polar and cartesian formats) to determine the actual change induced over the periods 1–2 and 2–3 months postop.Results:Chief findings were that the mean (n, ±SD, 95%CI) values for L over each period were as follows: Group 1, 0.407 (38, ±0.340, 0.299–0.521), 0.315 (23, ±0.184, 0.335–0.485); Group 2, 0.442 (45, ±0.423, 0.308–0.577), 0.372 (26, ±0.244, 0.335–0.485). Differences between groups were not significant. There was a significant linear relationship between (A) the change in K (ΔK = value at 1 month-value at 2 months) and K at 1 month (x), where ΔK =0.668-3.794X (r = 0.812, n = 38, P = <0.001) in group 1 and ΔK = 0.263x -1.462 (r = 0.494, n = 45, P = 0.002) in group 2, (B) L and the J45 vector describing the actual change in astigmatism between 1 and 2 months in group 2, where J45 (by autorefractometry) =0.287L-0.160 (r = 0.487, n = 38, P = 0.001) and J45 (by subjective refraction) =0.281L-0.102 (r = 0.490, n = 38, P = 0.002), and (C) J45 and ΔK between 2 and 3 months in group 2, where J45 (by subjective refraction) =0.086ΔK-0.063 (r = 0.378, n = 26, P = 0.020).Conclusion:Changes in the location of the first Purkinje image relative to the pupil center after phacoemulsification contributes to changes in refractive astigmatism. However, the relationship between the induced change in astigmatism resulting from a change in L is not straightforward.

Comparison of Small Incision Lenticule Extraction Surgery With and Without Cyclotorsion Error Correction for Patients With Astigmatism.

Purpose:To evaluate the add-on effect of manual cyclotorsion error correction by the cornea-marking method over standard small incision lenticule extraction (SMILE) surgery in astigmatic eyes.Methods:Consecutive patients (84) who had preoperative myopic astigmatism of −0.75 diopters (D) or more and were seeking surgical refractive correction by SMILE surgery during July 2017 to August 2017 were included in this study and randomized to treatment with standard SMILE surgery (S group: 30 eyes) or cyclotorsion compensated SMILE surgery (CC group: 54 eyes). The visual acuity and refractive outcomes were analyzed preoperatively and postoperatively. Refractive astigmatic changes were analyzed by the Alpins method.Results:The S and CC groups were comparable preoperatively regarding age, manifest spherical equivalent, and manifest refractive cylinder. The mean position-related cyclotorsion degree in the enrolled astigmatic eyes for the S and CC groups was 1.7 ± 2.2 degrees (ranging from 0 to 10 degrees) and 2.19 ± 1.74 degrees (ranging from 0 to 10 degrees), respectively. The mean cylinder was −1.67 ± 0.54 D versus −1.72 ± 0.71 D preoperatively. Six months after treatment, the surgical outcomes in the CC group were significantly better than those of the S group, with a postoperative corrected distance visual acuity of −0.07 ± 0.07 versus 0.016 ± 0.13. A vector analysis of astigmatism also yielded better outcomes in the CC group. However, these 2 groups were statistically similar in spherical equivalent.Conclusions:SMILE surgery combined with cyclotorsion error compensation yielded a significant improvement in surgical outcomes regarding safety, efficiency, and predictability for patients with astigmatism.

Correction of myopic astigmatism by small incision lenticule extraction: does laterality matter?

To evaluate the outcome after astigmatic correction of small incision lenticule extraction (SMILE) and to compare the refractive results of right eyes with left eyes. Patients who underwent SMILE surgery in our clinic between 2014 and 2016 (Visumax, Carl Zeiss Meditec, Germany) were retrospectively reviewed. Preoperative and postoperative manifest refractions and corrected and uncorrected visual acuities were evaluated and changes in refractive astigmatism were evaluated by vector analysis. One hundred twenty-one eyes from 82 patients with myopic astigmatism were included. The mean preoperative spherical equivalent was - 6 ± 1.7 (range from - 9.50 to - 1.25)D and the mean cylinderical power was - 1.5 ± 0.6 (range from - 3.75 to - 1.00)D. Postoperatively 71.8% of eyes had < 0.50D cylinder magnitude. Vector analysis results based on laterality revealed that correction index was 0.87 ± 0.3 for left eyes and 0.72 ± 0.3 for right eyes (p 0.02). This study revealed that SMILE has favorable astigmatic correction affect but left eyes have better outcomes than right eyes.

Pseudophakic astigmatism reduction with femtosecond laser-assisted corneal arcuate incisions: a pilot study.

PurposeThe aim of this study was to assess the effectiveness of the Verion-LenSx guided arcuate incision technique to reduce refractive astigmatism in a pseudophakic population.Patients and methodsA prospective single-arm study was conducted in which one or both eyes of subjects required reduction of 1.0–2.0 D of refractive astigmatism after previous cataract surgery or refractive lens exchange. The surgeon used the refractive cylinder in the eye and the Woodcock astigmatism nomogram for preoperative planning, while the LenSx femtosecond laser with the Verion Image Guided System was used to create all arcuate incisions. The primary outcome measure was the uncorrected monocular distance visual acuity (UCVA). Secondary outcome measures included the change in corneal astigmatism, the change in refractive astigmatism, the best-corrected visual acuity and spectacle independence at distance from preoperative stage to 1 month and 2 months postoperatively.ResultsTwenty-eight eyes of 18 subjects were treated. The best-corrected visual acuity at the 2-month postoperative (PO) stage was not statistically significantly different from the preoperative visual acuity (0.02 logarithm of the minimum angle of resolution [logMAR] in both cases, P>0.05). Uncorrected visual acuity was statistically significantly better at the 2-month PO stage relative to the preoperative value (0.14 versus 0.34 logMAR, P<0.01). The mean change in refractive cylinder from the preoperative stage to the 2-month PO stage was 1.0 D. At the 2-month PO stage, two-thirds of the subjects (12/18) reported that they did not use glasses for distance vision and that their spectacle use for distance vision at 2 months was “lower” or “much lower” than the preoperative stage; in 71% of eyes (20/28), the residual refractive cylinder was ≤0.50 D. Vector changes in keratometric astigmatism were weakly associated with changes in refractive cylinder.ConclusionArcuate incisions made with a femtosecond laser to treat moderate levels of residual refractive astigmatism after previous cataract surgery may reduce dependence on spectacles for distance vision.

Comparison of pre-operative and post-operative astigmatism and visual acuity after pterygium excision followed by sutureless and gluefree conjunctival autograft

Objective: To compare change in refractive astigmatism and visual acuity following pterygium excision followed by sutureless and gluefree conjunctival autograft.Method: A prospective , non randomized , comparative and interventional case series .This study was carried out on 52 eyes of 50 patients with primary pterygium in one or both eyes .our surgical technique comprised of pterygium excision followed by sutureless and gluefree conjunctival autograft which had additional benefit of having lowest recurrence rate at present. Visual acuity and refractive astigmatism were assessed pre-operatively and post – operatively on 2nd month follow up.Result: The mean age of the patient was 40.9 ±12.09 years .17 patients (32.69%) had grade III pterygium,12 patients each (23.07%) were of grade I and grade II and 21.15% were of grade IV. There was significant reduction in refractive astigmatism (mean±s.d) and improvement in visual acuity (mean±s.d) in all grades of pterygium post – operatively along with recurrence of merely in 1 patient i.e. 1.92 %.Conclusion: The present study concludes that pterygium excision reduces refractive astigmatism, improves visual acuity with additional benefit of lowest recurrence rate credited to sutureless and gluefree conjunctival autograft.

Vector analysis of astigmatic correction after small-incision lenticule extraction and femtosecond-assisted LASIK for low to moderate myopic astigmatism

AimTo compare astigmatic correction between femtosecond-assisted laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE).MethodsA total of 111 patients were included in this prospective study. Fifty-seven eyes were treated...

Clinical outcomes of wavefront-guided laser in situ keratomileusis to treat moderate-to-high astigmatism.

PurposeThe purpose of this study was to evaluate the refractive and visual outcomes of wavefront-guided laser in situ keratomileusis (LASIK) in eyes with myopic astigmatism and cylindrical component ≥2.0 diopter (D).MethodsIn this retrospective study, 611 eyes that underwent LASIK for simple or compound myopic astigmatism were analyzed. Preoperative refractive cylinder ranged from −2.00 D to −6.00 D (mean −2.76±0.81 D), and the sphere was between 0.00 D and −9.75 D (mean −2.79±2.32 D). Predictability, visual outcomes, and vector analysis of changes in refractive astigmatism were evaluated.ResultsAt 3 months after LASIK, 83.8% of eyes had uncorrected distance visual acuity of 20/20 or better, 90.3% had manifest spherical equivalent within ±0.50 D, and 79.1% had residual refractive cylinder within ±0.50 D of intended correction. The mean correction ratio for refractive cylinder was 0.92±0.14, the mean error of angle was −0.45°±2.99°, and the mean error vector was 0.37±0.38 D. A statistically significant correlation was found between the error of magnitude (arithmetic difference in the magnitudes between surgically induced refractive correction and intended refractive correction) and the intended refractive correction (r=0.26, P<0.01).ConclusionWavefront-guided LASIK for the correction of myopic astigmatism is safe, effective, and predictable.

Astigmatism among myopics and its changes from childhood to adult age: a 23-year follow-up study.

To study the prevalence of and changes in astigmatism from the onset of myopia at school age. Two hundred and forty myopic schoolchildren (mean age 10.9 years), with no previous spectacles, were recruited during 1983-1984 to a randomized 3-year clinical trial of bifocal treatment of myopia. Three annual examinations with subjective cycloplegic refraction were performed for 237-238 subjects. Subsequent examinations were performed at the mean ages of 23.2 and 33.9 years for 178 and 163 subjects, and the last examination, including data from prescriptions of different ophthalmologists, for 32 subjects. Corneal topography was studied at baseline, at the 3-year follow-up and at the two adulthood follow-ups. Prevalence and changes in refractive astigmatism (RA), in its polar values J0 and J45, and corneal astigmatism (CA) were studied. Mean RA of the right eye increased during follow-up from 0.26 D (SD) ± 0.30 to 0.79 D ± 0.74. Mean CA was 1.07 D ± 0.74 at study end. The prevalence of RA ≥0.25 or ≥1.00 D increased from 54.9 and 3.8% to 83.4 and 34.4%, respectively. The main direction of the axis of RA and its polar value J0 and CA changed mainly through sphericity, from against the rule (ATR) to with the rule during the follow-up. There was a negative correlation between RA and spherical refraction in the ATR group at end of follow-up. Changes in RA were associated with increase in myopia and with changes in CA. The prevalence and mean amount of RA associated with CA increased, and the axis of astigmatism changed among myopics during the 23-year follow-up.

Laser-Assisted In Situ Keratomileusis in High Mixed Astigmatism With Optimized, Fast-Repetition and Cyclotorsion Control Excimer Laser

To evaluate the visual refractive and aberrometric outcomes of laser-assisted in situ keratomileusis (LASIK) surgery for the correction of high mixed astigmatism using a new-generation excimer laser and optimized aspherical profiles. Retrospective interventional case series. Fifty-two eyes of 36 patients (21-53 years) with primary mixed astigmatism over 3.0 diopters (D) were included. All cases underwent LASIK surgery using the sixth-generation excimer laser Amaris with cyclotorsion control and a femtosecond platform for flap creation. Visual, refractive, corneal topographic, and aberrometric outcomes were evaluated during a 3-month follow-up. Refractive astigmatic changes were analyzed by Alpins method. A significant reduction of refractive sphere and cylinder was observed 3 months postoperatively (P = .001), with an associated improvement of uncorrected distance visual acuity (P = .001). Best-corrected distance visual acuity (CDVA) remained unchanged in 31 eyes (59.6%), while 3 eyes (5.76%) lost 2 lines of CDVA. Fourteen eyes (26.9%) had spherical equivalent (SE) within ±0.5 D of emmetropia and 34 (65.3%) had SE within ±1.0 D of emmetropia. No significant difference was observed when comparing surgically induced and target astigmatism. A significant induction of higher-order aberration attributable to increase of spherical aberration was found (P = .003). Seven eyes (13.4%) required retreatment. LASIK for primary high mixed astigmatism using optimized aspherical profiles and a fast-repetition-rate excimer laser with cyclotorsion control is a safe, effective, and predictable procedure. Induction of higher-order aberrations is still present in the correction of the refraction error of the magnitude included in this study.

Long-term visual performance of AT LISA 909M multifocal toric intraocular lenses

Purpose The aim of the study was to analyze the subjective and objective visual and astigmatic effect of AT LISA 909M multifocal toric intraocular lenses (IOLs) for far and near vision after 1 year of implantation. Design This is a prospective nonrandomized interventional case series. Methods After cataract surgery with implantation of AT LISA 909M multifocal toric IOLs, the visual, refractive, and corneal topographic outcomes, lens rotation, contrast sensitivity, and patient satisfaction were evaluated over 12 months and analyzed. Refractive astigmatic changes (target-induced astigmatism, surgically induced astigmatism, difference vector, magnitude of error, and flattening effect) were analyzed using the Alpins vectorial method. Results The study enrolled 22 eyes (11 patients). Postoperatively, a significant reduction was observed in the refractive cylinder (P Conclusion The AT LISA 909M multifocal toric IOL resulted in long-term visual improvement in distance and near vision with good predictability in eyes with moderate-to-high corneal astigmatism undergoing cataract surgery.

Vector analysis of astigmatic changes after cataract surgery with implantation of a new toric multifocal intraocular lens

To analyze the astigmatic changes after cataract surgery with the implantation of a new toric multifocal intraocular lens (IOL) using the Alpins vector method. Vissum-Instituto de Oftalmológico de Alicante, Alicante, Spain. Prospective case series. After cataract surgery with implantation of an AT Lisa 909M toric multifocal IOL, the visual, refractive, corneal topographic, internal astigmatism, defocus curves, and contrast sensitivity outcomes were evaluated over 6 months. Refractive astigmatic changes (target astigmatism [TIA]; surgically induced astigmatism [SIA]; difference vector; magnitude of error; flattening effect; torque) were analyzed using the Alpins vectorial method. The study enrolled 23 eyes (12 patients). Postoperatively, there was a significant reduction in refractive cylinder (P < .01) with an associated visual improvement for near (P = .03) and distance (P=.01). The magnitude of SIA vector was significantly larger than the TIA 3 months postoperatively (P = .03). The mean magnitude of the difference vector was 0.67 diopter (D) ± 0.51 (SD) at 6 months. The mean magnitude of error remained positive and close to zero over the entire follow-up (P ≥ .19). The mean magnitude of torque vector was 0.49 ± 0.54 D at 6 months. Significant positive correlation was found between the magnitude of torque and the difference vector (r ≥ 0.70, P<.01). The new toric IOL restored distance and near visual function with excellent predictability in eyes with moderate to high corneal astigmatism having cataract surgery.

Comparative Analysis of Clinical Outcomes Obtained With a New Diffractive Multifocal Toric Intraocular Lens Implanted Through Two Types of Corneal Incision

To analyze and compare the clinical outcomes obtained after cataract surgery with the implantation of a new multifocal toric intraocular lens (IOL) using two different types of corneal incision. Retrospective study including 64 eyes of 35 patients who underwent surgery with implantation of the AT LISA 909M multifocal toric IOL (Carl Zeiss Meditec) in 2 different ophthalmologic centers using different criteria for corneal incision size: sub-1.8 mm (micro-incision surgery [MICS] group) and 2.2 mm (mini-incision group). Visual, refractive, and corneal topographic outcomes were evaluated during 6-month follow-up. Additionally, refractive astigmatic changes were analyzed using the Alpins vectorial method. Significant reductions of refractive sphere and cylinder were observed postoperatively (P<.03), with associated visual improvements for near and distance (P<.01) in both groups. Mean postoperative magnitudes of difference vector, torque, and magnitude of error in the overall sample were 0.52±0.36 diopters (D), 0.36 ± 0.36 D, and 0.08 ± 0.38 D, respectively. A mean overcorrection of 4% in refractive astigmatism was found. Mean angle of error was 0.37± 5.50° and -4.51±13.16° for the MICS and mini-incision groups, respectively (P=.09). Significant positive correlations were found between the magnitudes of torque and difference vector (r=0.78, P<.01) as well as between the magnitude of torque and absolute angle of error (r=0.76, P<.01). Implantation of the AT LISA toric IOL using corneal incisions <2.2 mm provides excellent predictability for astigmatic correction.

Astigmatic Changes in Orthokeratology

To investigate and compare changes in refractive astigmatism and corneal toricity in orthokeratology (ortho-k) using the Thibos vector analysis. Consecutive records of 74 patients (aged 7 to 16 years) who were fitted with spherical ortho-k lenses at the Optometry Clinic of The Hong Kong Polytechnic University between April 2000 and November 2003 and who had been on the treatment for at least 6 months were reviewed. Manifest refractive error and topographic data were retrieved from the right eye for data analysis. Changes in refractive astigmatism and corneal toricity were evaluated using the Thibos vectors (refractive vectors, RJ 0 and RJ 45; corneal vectors, CJ 0 and CJ 45) among the astigmats (refractive astigmatism 0.75 diopters cylinder (DC) or above) and the non-astigmats (refractive astigmatism 0.50 DC or less). The mean changes in refractive astigmatism, RJ 0 and RJ 45 were 0.51 +/- 0.51 diopter (D), -0.31 +/- 0.35 D, and 0.09 +/- 0.16 D, respectively, among the astigmats; and 0.01 +/- 0.36 D, 0.00 +/- 0.17 D, and 0.03 +/- 0.13 D, respectively, among the non-astigmats. RJ 0 was significantly reduced, and RJ 45 was significantly increased only in the astigmats (one sample t tests, astigmats: p < 0.01; non-astigmats: p > 0.10). Although there were significant correlations between the initial RJ 0 and RJ 45 with their changes in all subjects and in the astigmats, only 21 to 55% of the variability could be explained by the regression equations (Pearson r: all subjects -0.63 < r < -0.62; astigmats -0.74 < r < -0.46, p < 0.001). No significant changes in corneal toricity and no correlations between the changes in refractive astigmatism and changes in corneal toricity were found (p > 0.13). Spherical ortho-k leads to significant changes in RJ0 and RJ45, but only 38% of the variance of the changes in all subjects could be explained by relationship between changes and the initial RJ0 or RJ45. No correlation between changes in refractive astigmatism and changes in corneal toricity was found, and ortho-k treatment did not induce astigmatism in our non-astigmatic subjects.

Endothelial Keratoplasty Using Donor Tissue Not Suitable for Full-Thickness Penetrating Keratoplasty

To evaluate the use of corneal donor tissue deemed unsuitable for full-thickness penetrating keratoplasty (PK) for use in deep lamellar endothelial keratoplasty (DLEK) and to compare postoperative results to those of DLEK surgery using donor tissue that is suitable for PK. Small-incision DLEK surgery was performed using 39 donor corneas unsuitable for PK. Thirty-five donors had anterior scars or opacities, 3 donors had pterygia within the 8-mm zone, and 1 had prior LASIK. All donor preparation was completed by manual stromal dissection. The DLEK surgical and postoperative courses were reviewed. Preoperative and 6-month postoperative results of this study group were compared with a control group consisting of the first 55 consecutive small-incision DLEK patients receiving donor corneas that had no criteria excluding them from use in PK. Four eyes in the study group and 1 eye in the control group had the confounding variables of the presence of an anterior-chamber lens or surgical vitrectomy with macular disease in the recipient eye. There was no significant difference in preoperative measurements of best spectacle-corrected visual acuity (BSCVA; P = 0.372), donor endothelial cell density (ECD; P = 0.749), or corneal topography [surface regularity index (SRI), P = 0.485; or surface asymmetry index (SAI), P = 0.154] between the 2 groups. For the patients receiving corneas deemed unacceptable for PK, at 6 months after surgery, the vision (P = 0.002) and corneal topography measurements improved significantly from before surgery (SRI, P < 0.001; SAI, P < 0.001), and there was no significant change in refractive astigmatism (P = 0.240). There was a significant difference in the vision at 6 months postoperatively between the overall study group and the control group, with the mean vision of the study group at 20/56 and the control group at 20/43 (P = 0.015). If eyes with known cystoid macular edema (CME) and vitrectomy are removed from each group, there is no significant difference in vision at 6 months between the study group and the control group (P = 0.110), with the average BSCVA of those receiving donor corneas unsuitable for PK equal to 20/48 (range, 20/25-20/200) and the average vision for those receiving PK-acceptable donor tissue equal to 20/43 (range, 20/20-20/80). The 6-month average refractive astigmatism of the study group was 1.12 +/- 0.99 D (range, 0.00-4.00 D), and the average endothelial cell count was 2064 +/- 396 cells/mm(2) (range, 1208-2957 cells/mm(2)). There was no significant difference in 6-month postoperative endothelial cell count (P = 0.443), refractive astigmatism (P = 0.567), or corneal topography (SRI, P = 0.332; SAI, P = 0.110) in study patients who received corneas unsuitable for PK compared with control patients who received corneas suitable for PK. Endothelial keratoplasty such as DLEK surgery with manual donor preparation broadens the donor pool by enabling corneas that cannot be used for PK to be used for selective endothelial transplantation without deleterious postoperative results.

Early Results of Small-Incision Descemet’s Stripping and Automated Endothelial Keratoplasty

To describe our technique and early results of Descemet's stripping and automated endothelial keratoplasty (DSAEK), identify perioperative complications, and discuss their management. Prospective, noncomparative, surgical case series. Twenty-six eyes of 26 patients who had corneal edema from Fuchs' endothelial dystrophy, pseudophakic bullous keratopathy, or aphakic bullous keratopathy. The donor corneal lenticule was prepared using a microkeratome and an artificial anterior chamber maintainer. Stripping of the diseased host endothelium was performed under viscoelastic using a 2.75-mm clear corneal temporal incision. The incision was enlarged to approximately 4.2 mm to allow placement of a folded 8.5-mm-diameter donor corneal lenticule. The donor graft was positioned using a temporary air bubble that was partially evacuated after 7 minutes. The corneal wound was closed with a single 10-0 nylon suture. Preoperative and postoperative best spectacle-corrected visual acuity (BSCVA), manifest refraction, keratometry, topographic astigmatism, corneal pachymetry, and perioperative complications. Three months postoperatively, all donor grafts remained clear. The average 3-month postoperative BSCVA was 20/45 (range, 20/20-20/150). The average change in refractive astigmatism was 0.12+/-1.15 diopters (D) (range, -1.50 to 3.25). In patients who underwent simple DSAEK (i.e., no intraocular lens implantation), the average postoperative shift in spherical equivalent refractive error was 1.15+/-1.35 D (range, -0.25 to +4.25). Nine of 26 initial grafts dislocated postoperatively and had to be repositioned. Three of the repositioned grafts dislocated again and were replaced with new donor corneal lenticules, all of which remained clear. Descemet's stripping and automated endothelial keratoplasty uses a mechanical microkeratome to harvest the donor corneal lenticule and mechanical stripping of the diseased host endothelium and Descemet's membrane. Despite a smooth graft-host interface, only 2 patients in the series achieved > or =20/25 vision. The average visual results were comparable to vision after deep lamellar endothelial keratoplasty. Although patients experienced excellent postoperative acuity with minimally induced surgical astigmatism, nearly one third of the donor lenticules needed to be either repositioned or replaced. Nevertheless, DSAEK offers significant advantages over standard penetrating keratoplasty for patients with Fuchs' dystrophy in pseudophakic bullous keratopathy.

Limbal relaxing incisions for primary mixed astigmatism and mixed astigmatism after cataract surgery

Purpose To evaluate the effect of limbal relaxing incisions (LRIs) in the treatment of primary mixed astigmatism and mixed astigmatism after cataract surgery. Setting Department of Ophthalmology, Inönü University, Malatya, Turkey. Methods Limbal relaxing incisions were performed to correct astigmatism in 37 eyes of 26 patients with mixed astigmatism. Twenty-four eyes had primary astigmatism, and 13 eyes had astigmatism after cataract surgery. The length, number, and depth of the incisions were determined using the Gills and Gayton nomogram. The manifest refractive astigmatism was measured preoperatively and 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. Surgically induced astigmatism using the vector method, preoperative and postoperative uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BSCVA) were evaluated. Follow-up was at least 6 months in all cases. Results The mean preoperative and postoperative refractive astigmatism was 3.31 diopters (D) ± 1.50 (SD) and 1.59 ± 1.28 D, respectively ( P < .001). The mean absolute change in refractive astigmatism was 1.72 ± 0.81 D. No patient lost lines of UCVA or BSCVA. The safety index was 1.21 and the efficacy index, 0.88. The mean preoperative and postoperative UCVA was 0.29 ± 0.22 and 0.54 ± 0.31, respectively ( P = .0001) and the mean BSCVA, 0.61 ± 0.30 and 0.74 ± 0.30, respectively ( P = .0001). The mean vectorial magnitude was 2.32 ± 1.36 D at the last follow-up. There were no serious postoperative complications. Conclusion Limbal relaxing incisions are a simple, safe, and effective method to correct primary mixed astigmatism and mixed astigmatism after cataract surgery.

Surgically induced astigmatism after hyperopic and myopic photorefractive keratectomy

Purpose To compare the axis and magnitude of surgically induced refractive astigmatism (SIA) after hyperopic and myopic photorefractive keratectomy (PRK). Setting Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. Methods In this single-center retrospective study, the VISX Star S2 excimer laser was used to create a peripheral annular ablation profile to correct spherical hyperopia in 23 eyes of 16 consecutive patients. Attempted corrections ranged from +0.50 diopter (D) to +4.25 D with 0 to 1.00 D of astigmatism. The same laser was used to create a central ablation profile to correct spherical myopia in 25 eyes of 17 consecutive patients. Attempted corrections ranged from –2.25 to –6.50 D with 0 to 1.00 D of astigmatism. The absolute change in refractive astigmatism was calculated by taking the difference in magnitudes of astigmatism before and after laser treatment without regard to axis. Axis and magnitude of SIA were analyzed by vector differences. Magnitudes were compared using the Student t test, and axial shifts were compared using the chi-square test. All patients were followed for a minimum of 6 months. Results The mean changes in absolute astigmatism were 0.29 ± 0.28 D at 3 months and 0.34 ± 0.29 D at 6 months after hyperopic PRK and 0.40 ± 0.35 D at 3 months and 0.39 ± 0.36 D at 6 months after myopic PRK. The mean vectoral magnitudes were 0.49 ± 0.29 at 3 months and 0.52 ± 0.25 at 6 months after hyperopic PRK and 0.48 ± 0.39 at 3 months and 0.44 ± 0.38 at 6 months after myopic PRK. The mean values for SIA (the centroid) were 0.10 ± 0.57 D × 113 degrees at 3 months and 0.15 ± 0.57 D × 131 degrees at 6 months after hyperopic PRK and 0.04 ± 0.63 D × 160 degrees at 3 months and 0.08 ± 0.58 D × 171 degrees at 6 months after myopic PRK. There was no statistically significant difference between the 2 groups in vectoral axis or magnitude of SIA. Conclusion Surgically induced astigmatism after hyperopic PRK was comparable to astigmatism induced by myopic PRK. A peripheral annular ablation for hyperopic correction, similar to a central ablation in myopic PRK, did not appear to result in uneven corneal healing causing astigmatism.