Postoperative Keratometric Astigmatism Research Articles

Postoperative Keratometric Astigmatism Axis Shift in Cataract Operated Adult Patients in National Eye Centre, Kaduna.

Postoperative Keratometric Astigmatism Axis Shift in Cataract Operated Adult Patients in National Eye Centre, Kaduna.

An analysis of factors associated with graft topographic outcomes after deep anterior lamellar keratoplasty.

To investigate the correlations between preoperative, operative, and postoperative factors and corneal graft topographic parameters after deep anterior lamellar keratoplasty (DALK) performed in keratoconus-affected eyes. This prospective, interventional study enrolled 44 eyes. Graft topographic parameters, including keratometric astigmatism and the surface regularity index (SRI), were assessed after complete suture removal. Univariate analyses were used to evaluate the effects of preoperative factors (donor quality, donor and recipient age, keratoconus severity), operative factors (graft size, donor button roundness, roundness and centration of the donor-recipient junction), and postoperative factors (time point of suture removal) on postoperative topographic parameters. The roundness of the donor-recipient junction after complete suture removal had a significant association with the roundness of the donor button after trephination (P = 0.04) and the amount of graft decentration relative to the limbus (P = 0.03). A significant correlation was found between the value of graft decentration relative to the limbus and postoperative keratometric astigmatism (P = 0.001) and between the roundness of the donor-recipient junction and the postoperative SRI (P = 0.02). The flat axis of the keratometric astigmatism and the longer axis of the graft lay in the direction of graft displacement. Other investigated factors had no significant association with postoperative topographic indices. Graft displacement relative to the limbus and roundness of the donor-recipient junction were the main predictors of graft astigmatism and regularity, respectively, after DALK. Noncircularity of the donor button after trephination could increase the graft surface irregularity indirectly by influencing the roundness of the surgical wound.

A study on evaluation of acrysof toric intraocular lens implantation to correct pre-existing corneal astigmatism in patients undergoing cataract surgery- At a tertiary care hospital

The current study evaluates the results of acrysof toric intraocular lens implantation to correct pre-existing corneal astigmatism in patients undergoing cataract surgery. This study was done on Prospective interventional at Osmania Medical College, Sarojini Devi Eye Hospital, Hyderabad. The sample of the study is included 40 eyes of 38 consecutive patients with 1.5 D or more of pre-existing astigmatism consists of cataract surgery with toric open-loop IOL implantation (Alcon, Fort Worth, TX, USA). The pre-operative markings for the position of incisions and IOL placement were being done under the slit lamp. The visual acuity, residual keratometric and refractive cylinders, and toric IOL axis were being measured. 54.71 years was the mean age of the patients. All the 40 eyes at the final check-up had post-operative unaided visual acuity of 6/12 or better. 10 patients (25 %) had an unaided visual acuity of 6/6.37 eyes (92.5%) had best corrected post-operative visual acuity of 6/9 or better. The mean pre-operative refractive astigmatism in 40 eyes was 2.34D. 22 eyes had the Refractive astigmatism of >2D. No eyes had refractive astigmatism of <1.5D. The mean axial length was 24.22mmOut of 40 eyes in which Toric IOL was implanted, the post-operative residual refractive sphere was seen in 4 eyes. Out of 40 eyes in whom Toric IOL was implanted, a post-operative residual refractive cylinder was seen in 30 eyes. 10 patients had No post-operative refractive cylinder. The mean post-operative residual refractive cylinder was 0.58D. The mean Post-operative Keratometric cylinder was 2.24D. The mean post-operative Keratometric cylinder was 2.34D. In comparison, both pre-operative and post-operative keratometric astigmatism, it was found that there was no statistically significant difference between them.The misalignment of Toric IOL was 10 degrees or less in 36 patients (94.73%) and less than 5 degrees in 22 patients (57.89%). Misalignment of >10 degrees (11 degrees and 13 degrees) was seen in 2 patients. The mean IOL rotation among 38 patients was 4.55 degrees (Range 0-13 degrees, SD 3.43). None of the eyes required repositioning. The results of this study show that implantation of AcrysofTor ic IOL is a good surgical method to evaluate pre-existing corneal astigmatism in cataract surgery. Acrysoftoric IOL has shown good rotational stability.

Vector analysis investigation of toric intraocular lens with no deviation from the intended axis.

AimThe aim of this research was to evaluate vector analysis after implantation of toric intraocular lenses (IOLs) without deviation from the intended axis.MethodsThe study included 18 eyes of 16 patients who underwent cataract surgery with the insertion of a toric implant (AcrySof IQ Toric). The postoperative IOL meridian placement completely corresponded to that planned. Using vector analysis, surgically induced astigmatism (SIA) was derived from the refractive outcome versus the predicted postoperative keratometric astigmatism and was compared with targeted induced astigmatism (TIA). The difference vector (DV) was derived by calculating the vector expression of the remaining astigmatic change.ResultsThe mean postoperative remaining refractive astigmatism of 0.73±0.55 diopters (D) was achieved versus the mean target of 0.44±0.28 D. There was a difference of 0.29 D between the target and achieved values. The mean SIA value was 1.90±0.99 D compared with the mean TIA value of 2.00±0.85 D. The mean DV value was 0.87±0.56 D. The astigmatism correction index (SIA/TIA) was 0.95, which was near the ideal value of 1. The index of success (DV/TIA) was 0.44, which was far from the ideal value of 0.ConclusionThe implantation of toric IOLs is an effective, predictable method for astigmatic correction. However, some remaining astigmatism is present even if toric IOLs are placed accurately.

Descemet Stripping Automated Endothelial Keratoplasty in Fuchs' Endothelial Dystrophy versus Pseudophakic Bullous Keratopathy.

Purpose:To compare clinical and confocal scan outcomes after Descemet stripping automated endothelial keratoplasty (DSAEK) performed for Fuchs’ endothelial dystrophy (FED) versus pseudophakic bullous keratopathy (PBK).Methods:This retrospective comparative study included 47 consecutive eyes of 39 patients with the diagnosis of FED (n = 29, group 1) or PBK (n = 18, group 2) that underwent DSAEK. Clinical outcomes were compared between the study groups. At the final follow-up examination, confocal microscopy was used to measure and compare central corneal and graft thickness as well as endothelial cell density and morphology between the two groups.Results:Mean age at the time of surgery was 65.2 ± 11.8 and 69.4 ± 12.5 years in groups 1 and 2, respectively (P = 0.27). Follow-up period was 23.6 ± 14.0 months in group 1 and 25.6 ± 15.7 months in group 2 (P = 0.79). Postoperative best spectacle-corrected visual acuity was significantly better in group 1 than in group 2 until postoperative month 6. Afterwards, the two study groups were comparable in this regard. At the final follow-up examination, spherical equivalent refractive error was + 0.39 ± 1.46 diopters (D) in group 1 and + 0.80 ± 1.47 D in group 2 (P = 0.45). Postoperative keratometric astigmatism was 1.02 ± 0.83 D and 2.36 ± 0.67 D, respectively (P < 0.001). Mean central graft thickness was 98.0 ± 33.3 μm in group 1 and 107.6 ± 28.0 μm in group 2 (P = 0.45). No statistically significant difference was observed between the two groups in terms of the postoperative endothelial cell density.Conclusion:The outcomes of DSAEK surgery were comparable between FED and PBK. All grafts were clear despite the lower than normal endothelial cell counts.

Femto Circular Keratotomy to Halt the Progression of Keratoconus I and II

ABSTRACTAimTo simplify and enhance safety in the generation of a stabilizing intracorneal scar by circular keratotomy (CKT). A femtosecond laser was used to perform individually sized intraparenchymal cuts.Materials and methodsAs equipped, the Ziemer Z6 femto-second laser cuts a 400-µm-deep incision with a diameter of 7.0 mm around the optical axis. The epithelium, Bowmann's membrane, the internal borders of Descemet's membrane, and the endothelium are not affected.The 3-, 6-, and 12-month postoperative values were compared with the 1-month postoperative keratometric readings and astigmatism. The preoperative best corrected visual acuity (BCVA) with glasses was compared with the values found at the same time points as noted above.ResultsStatistical evaluation indicated that keratometry within ±1.5D remained in 96.6, 93.1, and 96.6% of cases at the 3-, 6-, and 12-month time points respectively.Astigmatism was stable at the same time points in 100, 95.8, and 92.3%.The BCVA improved in 12 cases throughout the first post-operative year (48%, n = 25); however, 11 cases did not change (44%) and 2 cases lost at least one line (8.0%).ConclusionFemto CKT halts the progression of keratoconus for at least 1 year in 96.6% of cases. This treatment provides keratometric and refractive stability for over 1 year. This result, in conjunction with the significant improvement in BCVA, demonstrates the potential of this method for patients with stage I and II keratoconus.How to cite this articleKrumeich JH, Hirnschall N, Breyer D, Laufer F. Femto Circular Keratotomy to Halt the Progression of Keratoconus I and II. Int J Kerat Ect Cor Dis 2016;5(3):109-113.

Factors Predicting Refractive Outcomes After Deep Anterior Lamellar Keratoplasty in Keratoconus

To determine the factors that predict refraction, mean keratometry, and keratometric astigmatism after deep anterior lamellar keratoplasty (DALK) in keratoconus. Consecutive interventional case series. This study enrolled 194 consecutive eyes of 181 patients with keratoconus who underwent DALK using the big-bubble technique. Indications for surgery included contact lens intolerance or poor corrected visual acuity. Univariate analyses and analysis of covariance were used to investigate recipient-, surgical-, and postoperative-related variables capable of predicting refractive outcomes, including mean keratometry, keratometric astigmatism, and spherical equivalent refraction. The mean patient age was 27.9 ± 8.2 years, and the patients were followed for 35.9 ± 18.2 months postoperatively. Preoperative mean keratometry (P = .007), time interval from surgery to running suture removal (P = .01), and suture-tract vascularization (P = .04) significantly influenced postoperative mean keratometry. Vitreous length predicted postoperative spherical equivalent (P = .03). Postoperative keratometric astigmatism failed to demonstrate any significant correlation with the preoperative, surgical, and postoperative variables. Postoperative refractive outcomes did not change relative to patient age and sex, central and peripheral corneal thickness, recipient trephination size, surgical technique (big-bubble vs manual dissection DALK), duration of steroid administration, and elevated intraocular pressure. Keratoconus patients with an elongated posterior segment and/or steep corneas should be informed of the need for postoperative optical correction after DALK. Running suture removal should be postponed for as long as possible if there is no suture-related complication.

English

BACKGROUND: To study the effect of paired opposite clear corneal incisions on the steep axis on preexisting corneal astigmatism in phacoemulsification. MATERIALS AND METHODS: This study was performed on 30 eyes of 30 patients who had keratometric astigmatism of more than 1 diopter. All patients underwent clear corneal phacoemulsification with a 3.2mm clear corneal incision on the steep axis. An additional similar incision was placed on the steep axis opposite to the first incision at the end of surgery. Preoperative keratometric astigmatism was compared with postoperative keratometric astigmatism at 6 weeks postoperatively. RESULTS: The difference between the median score of preoperative keratometric astigmatism and postoperative astigmatism was 1 diopter. Results were analyzed with wilcoxon signed rank test and were significant p value. (<1) CONCLUSION: Paired opposite clear corneal incisions is a simple method to correct mild to

Comparison of Descemet-On Versus Descemet-Off Deep Anterior Lamellar Keratoplasty

To determine the effect of retained donor Descemet membrane (DMs) on visual outcomes, contrast sensitivity (CS), higher-order aberrations (HOAs), and central graft thickness after deep anterior lamellar keratoplasty (DALK) using the big-bubble technique. In this retrospective comparative study, keratoconic eyes undergoing a DALK using the big-bubble technique were enrolled. A bared DM was achieved in all cases. A donor cornea without (group 1; 48 eyes) or with (group 2; 22 eyes) DM was sutured to the recipient bed. The 2 groups were compared in terms of best spectacle-corrected visual acuity, keratometric astigmatism, refractive error, CS, HOAs, and central graft thickness at least 3 months after complete suture removal. Additionally, the rate of postoperative pseudoanterior chamber formation was compared between the study groups. The mean follow-up duration was 23.2 ± 6.9 months in group 1 and 26.5 ± 6.5 months in group 2 (P = 0.61). The postoperative best spectacle-corrected visual acuity was 0.18 ± 0.08 logMAR and 0.24 ± 0.30 logMAR, respectively (P = 0.36). The 2 groups had comparable postoperative keratometric astigmatism, spherical equivalent refraction, and HOAs. In terms of CS, however, group 1 demonstrated better results at a low spatial frequency. The mean postoperative central graft thickness was greater in group 2 (589.8 ± 34.5 μm) than in group 1 (523.6 ± 63.0 μm; P < 0.001). A pseudoanterior chamber developed in 3 eyes of group 1 and in 2 eyes of group 2 (P = 0.23). All cases were successfully managed by giving an intracameral air injection. DALK performed using the big-bubble technique for keratoconus may give better results in terms of CS if a donor cornea without DM is transplanted.

Comparison of the keratometric corneal astigmatism and refractive astigmatism after phacoemulsification and foldable intraocular lens implantation

Here we aimed to define keratometric and refractive astigmatism in a series of patients who underwent phacoemulsification, using small corneal incision and implantation of foldable intraocular lenses. Furthermore, we compared keratometric astigmatism and refractive astigmatism of the patients both before and after surgery. We performed a follow-up study of patients with newly diagnosed cataract before and after phacoemulsification surgery. Eighty eyes from 78 patients with a mean age of 62.9±12.03 (32-86) years were studied. Thirty-nine (48.8%) were male and 41(51.2%) were female. All subjects underwent 3.5mm corneal incision with the temporal (75 patients; 94%) or superior (5 patients; 6%) approach. The patients were followed for a mean of 74.21±71.25 (30-400) days. Patients had higher values of keratometric measurements after surgery compared to those before surgery [45.81±0.11 (45.06-45.94) vs. 45.2±0.20 (44.6-45.41)] (p<0.001). There was no significant difference in the keratometric astigmatism, refractive astigmatism and keratometry axis pre- and postoperatively. The mean keratometric astigmatism was 0.9±0.54 (0.00-4.00) diopters (D) preoperatively and 0.93±0.45 (0.00-4.00) D postoperatively (p=0.444). The keratometric axis was 97.7±9.4 preoperatively and 115±15.8 postoperatively (p=0.185). Refractive astigmatism was 1.15±0.77 (5-180) with the refractive axis of 89.7±5.89 (5-180) degrees in the follow-up (p=0.752). Ninety percent of the patients had <1.00 D difference in the keratometric and refractive astigmatism, postoperatively. In conclusion while there is no significant difference in postoperative keratometric and refractive astigmatism in most of the eyes, about 10% show >1 D difference in these measurements.

Can opposite clear corneal incisions have a role with post-laser in situ keratomileusis astigmatism?

Purpose:To evaluate the astigmatic correcting effect of paired opposite clear corneal incisions (OCCIs) on the steep axis in patients with residual astigmatism after laser in situ keratomileusis (LASIK)Materials and Methods:Thirty-one eyes of 24 patients with a mean age of 28.4 years ±2.46 (range, 19-36 years) were recruited for the study. Inclusion criteria included residual astigmatism of ≥1.5 diopter (D) after LASIK with inadequate residual stromal bed thickness that precluded ablation. The cohort was divided into two groups; group I (with astigmatism ranging from -1.5 D to -2.5 D) and group II (with astigmatism > -2.5 D). The steep axis was marked prior to surgery. Paired three-step self-sealing opposite clear corneal incisions were performed 1-mm anterior to the limbus on the steep axis with 3.2-mm keratome for group I and 4.1 mm for group II. Patients were examined 1 day, 1 week, 1 month, 3 months and 6 months, postoperatively. Visual acuity, refraction, keratometry, and corneal topography were evaluated preoperatively and postoperatively. Analysis of the difference between groups was performed with the Student t-test. P<0.05 was considered statistically significant.Results:The mean uncorrected visual acuity (UCVA) improved from 0.35±0.13 (range, 0.1-0.6) to 0.78±0.19 (range, 0.5-1) in group I and from 0.26±0.19 (range, 0.1-0.5) to 0.7±0.18 (range, 0.4-1) in group II. The increase in UCVA was statistically significant in both groups (P=0.001, both cases). The mean preoperative and postoperative keratometric astigmatism in group I was 2.0±0.48 D (range, 1.5-2.5 D) and 0.8±0.37 D (range, 0.1-1.4 D), respectively. The decrease in keratometric astigmatism was highly statistically significant in group II (P=0.001.). Mean surgically induced astigmatic reduction by vector analysis was 1.47±0.85 D and 2.21±0.97 D in groups I and II respectively. There were no incision-related complications.Conclusions:Paired OCCIs were predictable and effective in correcting post-LASIK astigmatism and required no extra surgical skill or expensive instruments. OCCIs are especially useful in eyes with insufficient corneal thickness for LASIK retreatment.

Toric Intraocular Lens Outcome Using the Manufacturer's Prediction of Corneal Plane Equivalent Intraocular Lens Cylinder Power

To describe the refractive outcome of toric intraocular lens (IOL) implantation by comparing the postoperative refractive astigmatism with the preoperative keratometric astigmatism target. In a university department of a publicly funded hospital, 38 eyes of 29 patients underwent routine cataract surgery with insertion of a toric implant (SN60TT AcrySof Toric). Surgically induced astigmatism was derived using vector analysis of refractive outcome vs predicted postoperative keratometric astigmatism and compared with the targeted induced astigmatism. Postoperative remaining refractive astigmatism of 0.97 diopters (D) was achieved vs a target of 0.61 D. A mean (SD) surgically induced astigmatism value of 1.78 (0.89) D was derived compared with a mean (SD) targeted induced astigmatism value of 1.58 (0.47) D (calculated by the manufacturer's online calculator, which predicts IOL corneal plane equivalent cylinder power and postoperative keratometric cylinder). Toric IOLs are a safe, predictable method of astigmatic correction. However, some remaining astigmatism is commonly present owing to the necessary nonzero astigmatic targets imposed by the steps between IOL cylinder powers, variability of axis, and power effects of surgical incisions as well as by underestimation of the corneal plane cylinder power of the IOLs by the manufacturer.

Correlation between keratometric and refractive astigmatism in pseudophakic eyes

To determine the correlation between refractive and keratometric astigmatism in pseudophakic eyes. Vissum Madrid, Madrid, Spain. Case series. Consecutive eyes that had phacoemulsification with intraocular lens implantation during the first quarter of 2003 were evaluated. The refractive and keratometric astigmatism were compared 2 months postoperatively. The mean postoperative keratometric astigmatism (0.91 diopter [D] ± 0.67 [SD]) in the 121 eyes was statistically significantly higher than the mean postoperative refractive astigmatism (0.64 ± 0.72 D) (P<.0001). Regression analysis found a significant correlation between the refractive and keratometric errors of the J0 component (P<.001, r(2) = 0.29) and between the refractive and keratometric errors of the J45 component (P<.001, r(2) = 0.36) Keratometric astigmatism was responsible for about 30% of the refractive astigmatism in pseudophakic eyes. Other undetermined factors induce astigmatism in these cases.

Visian Toric Implantable Collamer Lens for Correction of Compound Myopic Astigmatism

To assess the safety, efficacy, predictability, and stability of a toric posterior chamber phakic intraocular lens for the correction of myopia with astigmatism. A non-randomized, retrospective analysis of 63 eyes of 36 patients with a minimum follow-up of 6 months was performed. The STAAR Toric Implantable Collamer Lens (TICL) was implanted under topical anesthesia through a 3-mm temporal clear corneal incision. Mean preoperative spherical equivalent refraction was -10.71+/-3.55 diopters (D). Median preoperative best spectacle-corrected visual acuity (BSCVA) was 20/25, with a mean sphere of -8.78 D (range: -2.50 to -16.50 D) and mean cylinder of 3.60 D (range: 1.25 to 7.00 D). Postoperative parameters were analyzed at different time points, and vector analysis was performed to calculate surgically induced astigmatism. Fifty-nine (93.6%) eyes had a spherical equivalent refraction within +/-1.00 D and 52 (82.5%) eyes were within +/-0.50 D of emmetropia. Median postoperative uncorrected visual acuity was 20/25 and BSCVA was 20/20. Preoperative keratometric astigmatism was 1.99@178.2 vs 1.82@178.6 postoperative keratometric astigmatism, most likely due to the surgical incision. Preoperative refractive astigmatism was 2.17@93 whereas postoperatively it reduced to 0.38@99.6. No eye lost 2 or more lines of Snellen BSCVA. Twenty-two (34.9%) eyes gained 2 or more Snellen lines of vision. Preoperatively, 45 (71.4%) eyes had a BSCVA of 20/30 or better, whereas 60 (95.2%) eyes were within this range of BSCVA after surgery. The TICL demonstrated good rotational stability in this study. Implantation of the STAAR TICL was an effective, predictable, and safe method for correction of high myopia and myopic astigmatism as shown in this retrospective observational series.

Induced Astigmatism With 2.2- and 3.0-mm Coaxial Phacoemulsification Incisions

To evaluate the difference between 2.2-mm incision micro-coaxial phacoemulsification and traditional 3.0-mm coaxial phacoemulsification with respect to surgically induced astigmatism after temporally oriented clear corneal incision cataract surgery. This prospective, randomized, intra-patient controlled study comprised 22 patients who underwent clear corneal cataract surgery in both eyes. One eye received 2.2-mm incision micro-coaxial phacoemulsification with intraocular lens (IOL) implantation and the fellow eye received traditional 3.0-mm coaxial incision phacoemulsification with IOL implantation. The 2.2-mm incisions were created with a diamond keratome after a 200-microm groove was constructed in clear cornea at the temporal limbus. The 3.0-mm incisions were created without a pre-cut groove, using a metal keratome. All cases were uncomplicated. Pre- and postoperative keratometric astigmatism at 6 weeks was measured using a hand held Nikon Retinomax K-plus 2 Autorefractor. Three methods were used to analyze the surgically induced astigmatism (SIA) data: 1) algebraic analysis of the magnitude of keratometric astigmatism induced by the surgery, 2) magnitude of SIA by vector analysis, and 3) aggregate analysis of astigmatism using vector analysis. The mean change in the magnitude of keratometric astigmatism was 0.10+/-0.08 diopters (D) with the 2.2-mm micro-coaxial incisions and 0.32+/-0.20 D with the 3.0-mm traditional incisions (P=.0002). Usingvector analysis, the mean magnitude of SIA was 0.35+/-0.21 D with the 2.2-mm incisions and 0.67+/-0.48 D (P=.006) with the 3.0-mm incisions. Surgically induced astigmatism with 2.2-mm micro-coaxial incisions and traditional 3.0-mm clear corneal incisions with intra-patient control resulted in statistically and clinically significant reduction in surgically induced astigmatism with the smaller incision size.

Phacoemulsification with nondominant hand

Evaluation of on axis phacoemulsification surgery through temporal incision using nondominant hand with surgeon sitting at the head end, inpatients with against-the-rule astigmatism. Eighty eyes of 80 patients who underwent phacoemulsification through a temporal clear corneal tunnel for age-related cataract and against-the-rule astigmatism were enrolled and divided into four equal groups. In Group 1A, the surgeon was sitting at the head end for the left eye performing surgery with the left hand (nondominant hand). In group 1B, the surgeon was seated at the temporal side and surgery was performed in the left eye with dominant right hand. In group 2A, the surgeon was sitting at the head end for the right eye and performed surgery holding the phacoemulsification hand piece in his right hand. In group 2B, the surgeon sat on the temporal side of the right eye and performed phacoemulsification with his right hand. The patients were followed up on day 7, 1 month, and 3 months. Parameters evaluated included average phaco power, effective phaco time, uncorrected and best-corrected visual acuity, keratometry, intraocular pressure, surgically induced astigmatism, pachymetry, and endothelial cell counts. The phaco time and phaco power among the four groups were comparable (phaco time: P=0.368; phaco power: P=0.294). The four groups were also comparable on parameters like surgically induced astigmatism (P=0.674), change in postoperative keratometric astigmatism (P=0.584), endothelial cell loss (0.921), change in ultrasonic pachymetry (P=0.476), and intraocular pressure (P=0.942). No intraoperative or postoperative complications were observed in any of the groups. The mean uncorrected visual acuity at 3 months in group 1 was 0.723+/-0.21; in group 2 it was 0.756+/-0.21; in group 3 it was 0.748+/-0.22, and in group 4 it was 0.732+/-0.23. The best-corrected visual acuity was 0.96+/-0.10, 0.97+/-0.11, 0.95+/-0.13, and 0.96+/-0.10 in the four groups at 3 months. Phacoemulsification surgery can be successfully performed with nondominant hand with a good surgical outcome. The technique gives an alternative approach where surgeon does not have to shift the position to perform on-axis phacoemulsification.

Corneal relaxing incision combined with phacoemulsification and IOL implantation.

To analyze the effectiveness and safety of corneal relaxing incisions (CRI) in correcting keratometric astigmatism during cataract surgery. A prospective study of two groups: control group and treatment group. A treatment group included 25 eyes of 25 patients who had combined clear corneal phacoemulsification, IOL implantation and CRI. A control group included 25 eyes of 25 patients who had clear corneal phacoemulsification and IOL implantation. Postoperative keratometric astigmatism was measured at 1 week, 1 month, 3 months and 6 months. CRI significantly decreased keratometric astigmatism in patients with preexisting astigmatism compared with astigmatic changes in the control group. In eyes with CRI, the mean keratometric astigmatism was 0.29+/-0.17 D (range 0 to 0.5 D) at 1 week, 0.41+/-0.21 D (range 0 to 0.82 D) at 1 month, respectively reduced by 2.42 D and 2.30 D at 1 week and 1 month postoperatively (P=0.000, P=0.000), and postoperative astigmatism was stable until 6 months follow-up. The keratometric astigmatism of all patients decreased to less than 1.00 D postoperatively. CRI is a practical, simple, safe and effective method to reduce preexisting astigmatism during cataract surgery. A modified nomogram is proposed. The long-term effect of CRI should be investigated.

Peripheral corneal relaxing incisions combined with cataract surgery

Purpose To analyze the effectiveness of peripheral corneal relaxing incisions (PCRIs) in correcting corneal astigmatism during cataract surgery. Setting Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Methods In 115 eyes of 94 patients (mean age 69 years ± 12 [SD]), cataract surgery was combined with PCRIs. The PCRIs were created according to a nomogram based on age and preoperative keratometric astigmatism. Postoperative keratometric astigmatism was measured at 1 day and 1 and 4 months. Vector analyses using the Holladay-Cravy-Koch formula and Alpins method were performed. Results The PCRIs significantly decreased keratometric astigmatism in patients with preexisting with-the rule (WTR) or against-the-rule (ATR) astigmatism and increased the percentage of the eyes with lower keratometric astigmatism in each group. Four months postoperatively in patients with WTR astigmatism, single and paired 6.0 mm PCRIs induced mean with-the-wound minus against-the-wound changes (WTW–ATW) of −0.55 diopter (D) and −1.18 D, respectively. In eyes with ATR astigmatism, the mean WTW–ATW changes induced by single 4.5 mm, single 6.0 mm, and paired 6.0 mm PCRIs were −2.18 D, −2.02 D, and −2.72 D, respectively. These mean WTW–ATW changes did not significantly regress from 1 day to 4 months postoperatively. Conclusions Peripheral corneal relaxing incisions were effective in reducing preexisting astigmatism during cataract surgery. A modified nomogram is proposed. The long-term effect of PCRIs should be evaluated.

Long-term results of corneal wedge excision for pellucid marginal degeneration.

A retrospective study reporting long-term visual and astigmatic results of patients with pellucid marginal degeneration (PMD) treated by corneal wedge excision. The notes of 9 patients (10 eyes) treated by corneal wedge excision were reviewed. All patients had typical PMD and were treated by excision of an inferior crescent of diseased corneal tissue. The excised area measured approximately 2 mm in width and extended from the 4 o'clock to the 8 o'clock meridian. All thinned corneal tissue was removed. Normal-thickness corneal stroma was then reapposed with 10/0 nylon or 10/0 polypropylene sutures. Post-operative selective suture removal was performed until a satisfactory visual and astigmatic result was achieved. This was guided by refraction, keratometry and photo-keratoscopy results. Pre-operative best corrected visual acuity ranged from 6/12 to 6/60 with an associated mean keratometric astigmatism of +13.8 dioptres (range 8-25 dioptres, axis range 30 degrees-175 degrees). Mean follow-up was 59 months (range 14-138 months). Post-operatively a stable corrected visual acuity of 6/9 or better was achieved in all cases in a mean time of 5.4 months (range 3-12 months). Mean post-operative keratometric astigmatism was 1.4 dioptres (range 0.5-4 dioptres). Over the course of follow-up long-term astigmatic drift (LTAD) was noted, mean 2.1 dioptres (range 0.5-5.5 dioptres). Three patients developed mild inferior pannus related to peripherally sited sutures. One case developed apparent corneal hydrops within the corneal wound after 9 years of follow-up. We believe that corneal wedge excision offers an excellent surgical result for patients with PMD, although modification of the technique may be required to improve long-term astigmatic drift.

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.