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Scientific Reports Oct 2022Bullous keratopathy (BK) is known to present with corneal edema and Descemet's folds, which can cause corneal astigmatism. However, no report quantitatively evaluated BK...
Bullous keratopathy (BK) is known to present with corneal edema and Descemet's folds, which can cause corneal astigmatism. However, no report quantitatively evaluated BK astigmatism by separating it into regular and irregular astigmatism. This study investigated the regular and irregular astigmatism of the anterior and posterior corneal surface with Fourier harmonic analysis and anterior segment optical coherence tomography. Preoperative data from 43 eyes of 41 BK patients who received corneal endothelial transplantation were compared with the data from 43 eyes of 43 subjects without corneal disease. Anterior and posterior cylinder power, central corneal thickness (CCT) and thinnest corneal thickness were significantly greater in BK. With Fourier harmonic analysis, BK eyes were found to have significantly larger anterior and posterior regular astigmatism, asymmetry component and higher-order irregularity. Asymmetry component and higher-order irregularity that accounted for the posterior irregular astigmatism increased as CCT increased in BK. Higher-order irregularity in the posterior cornea also positively correlated with worsening best corrected visual acuity. Subgroup analysis found significant correlations between CCT and posterior higher-order irregularity for intraocular surgery and laser iridotomy, but not Fuchs endothelial corneal dystrophy. This study has significance in that it revealed the characteristics of the corneal posterior irregular astigmatism of BK.
Topics: Humans; Astigmatism; Corneal Topography; Tomography, Optical Coherence; Corneal Edema; Cornea; Corneal Diseases; Fourier Analysis
PubMed: 36284222
DOI: 10.1038/s41598-022-22144-w -
Scientific Reports Jun 2021The aim of the study is to explore the distribution patterns and internal correlations of the morphological parameters of the cornea in patients with age-related... (Clinical Trial)
Clinical Trial
The aim of the study is to explore the distribution patterns and internal correlations of the morphological parameters of the cornea in patients with age-related cataract. The Pentacam HR was used to measure anterior corneal astigmatism (ACA), posterior corneal astigmatism (PCA), total corneal astigmatism (TCA) and keratometric corneal astigmatism (KCA). With age, the proportion of with-the-rule (WTR) ACA decreased from 65.31% to 23.63%, while the against-the-rule (ATR) ACA increased from 26.53% to 56.20%. PCA exceeded 0.50 D in 9.14% of eyes, while 76.35% of them were ATR. The magnitude of ACA was positively correlated with PCA in the whole sample, with a more significant correlation in WTR eyes (s = 0.349, P < 0.001). The vector summation effect of PCA to ACA changed from compensation to augmentation with aging. In 57.53% of WTR eyes, KCA was overestimated by an average of 0.21 ± 0.17 D, while it was underestimated by 0.38 ± 0.27 D in 87.62% of ATR eyes. In conclusion, among age-related cataract patients, ACA and TCA gradually shifted from WTR to ATR with aging, while most PCA remained as ATR. Ignoring the age-related changes and real PCA might cause overestimation of WTR astigmatism and underestimation of ATR astigmatism.
Topics: Adult; Aged; Aged, 80 and over; Aging; Astigmatism; Cataract; Corneal Topography; Female; Humans; Male; Middle Aged
PubMed: 34075156
DOI: 10.1038/s41598-021-91028-2 -
Ceska a Slovenska Oftalmologie :... 2023To analyze changes in surgically induced corneal astigmatism and articial intraocular lens (IOL) stability over time following cataract surgery. To compare the... (Observational Study)
Observational Study
AIMS
To analyze changes in surgically induced corneal astigmatism and articial intraocular lens (IOL) stability over time following cataract surgery. To compare the interchangeability of measurements between an automatic keratorefractometer (AKRM) and a biometer.
MATERIAL AND METHODS
In this prospective observational study, the above-mentioned parameters were collected from 25 eyes (25 subjects) on the first day, first week, first and third month after uncomplicated cataract surgery. We used IOL-induced astigmatism (difference between refractometry and keratometry) as an indirect indicator of IOL stability change. We used the Blant-Altman method to analyze consistency between devices.
RESULTS
At the above time points, surgically induced astigmatism (SIA) decreased as follows: 0.65 D; 0.62 D; 0.60 D and 0.41 D (in the first day, week, month and third month respectively). Astigmatism induced by changes of the position of the IOL varied as follows: 0.88 D; 0.59 D; 0.44 D and 0.49 D. Changes in both parameters were statistically significant (p0.05).
CONCLUSION
Both surgically induced astigmatism and astigmatism induced by IOL decreased over time, in which both changes were statistically significant. The decrease in SIA was most pronounced between the first and third month after surgery. For IOL-induced astigmatism, the greatest decrease was within the first month after surgery. The differences in measurement between the biometer and AKRM were statistically insignificant, but the clinical interchangeability between the given methods is questionable, especially with regard to measurement of the astigmatism angle.
Topics: Humans; Lens Implantation, Intraocular; Astigmatism; Phacoemulsification; Lenses, Intraocular; Corneal Diseases; Cataract; Refraction, Ocular
PubMed: 37072256
DOI: 10.31348/2023/14 -
Indian Journal of Ophthalmology Jan 2018Small incision lenticule extraction (SMILE), a variant of refractive lenticule extraction technology is becoming increasingly popular, as a flapless and minimally... (Review)
Review
Small incision lenticule extraction (SMILE), a variant of refractive lenticule extraction technology is becoming increasingly popular, as a flapless and minimally invasive form of laser vision correction (LVC) for the treatment of myopia and myopic astigmatism. This review aims at summarizing the principles, surgical technique, and clinical outcomes in terms of visual and refractive results, safety, efficacy, postoperative dry eye, aberrations, and biomechanics of SMILE and its comparison with other conventional techniques of LVC, such as laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Recent advancements in the laser frequency and energy delivery patterns, instrumentation, and surgical techniques have shown significant improvement in the visual recovery and outcomes after SMILE, compared to the initial results published by Sekundo and Shah et al. Most of the recently published literature on long-term outcomes of SMILE shows excellent stability of the procedure, especially for higher myopia. In terms of the postoperative dry eye, SMILE shows a clear advantage over LASIK as numerous studies have shown significant differences about the Schirmer's, Tear film break up time, corneal sensitivity, and corneal nerve regeneration to be better following SMILE compared to LASIK. There is some evidence that since the Bowman's membrane (BM) and the anterior lamellae remain intact after SMILE, this may be a potential advantage for corneal biomechanics over LASIK and PRK where the BM is either severed or ablated, respectively, however, the data on biomechanics are inconclusive at present. Overall, this procedure has proved to be promising, delivering equivalent, or better visual and refractive results to LASIK and providing clear advantage in terms of being a flapless, minimally invasive procedure with minimal pain and postoperative discomfort thus offering high patient satisfaction.
Topics: Astigmatism; Corneal Stroma; Humans; Microsurgery; Myopia; Refractive Surgical Procedures; Visual Acuity
PubMed: 29283117
DOI: 10.4103/ijo.IJO_761_17 -
Indian Journal of Ophthalmology Dec 2021To determine the significance of any association between either change in angle kappa (Κ°) or the rectilinear displacement (L, mm) of the first Purkinje image relative...
PURPOSE
To determine the significance of any association between either change in angle kappa (Κ°) 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 Κ (ΔΚ = value at 1 month-value at 2 months) and Κ at 1 month (x), where ΔΚ =0.668-3.794X (r = 0.812, n = 38, P = <0.001) in group 1 and ΔΚ = 0.263x -1.462 (r = 0.494, n = 45, P = 0.002) in group 2, (B) L and the J vector describing the actual change in astigmatism between 1 and 2 months in group 2, where J (by autorefractometry) =0.287L-0.160 (r = 0.487, n = 38, P = 0.001) and J (by subjective refraction) =0.281L-0.102 (r = 0.490, n = 38, P = 0.002), and (C) J and ΔΚ between 2 and 3 months in group 2, where J (by subjective refraction) =0.086ΔΚ-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.
Topics: Astigmatism; Humans; Lens Implantation, Intraocular; Lenses, Intraocular; Phacoemulsification; Refraction, Ocular; Visual Acuity
PubMed: 34826984
DOI: 10.4103/ijo.IJO_572_21 -
Indian Journal of Ophthalmology Feb 2022To primarily compare surgically induced astigmatism (SIA), total and posterior corneal curvature, pachymetry, and their stabilization after 2.2 and 2.8 mm clear corneal... (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
To primarily compare surgically induced astigmatism (SIA), total and posterior corneal curvature, pachymetry, and their stabilization after 2.2 and 2.8 mm clear corneal incision in phacoemulsification.
METHODS
A randomized, prospective interventional study of 130 patients (130 eyes) of either sex having senile cataract (>40 years) divided randomly into two groups. The patients underwent uncomplicated phacoemulsification surgery with foldable intraocular lens implantation using 2.2 mm (group 1) and 2.8 mm incisions (group 2). The patients were evaluated preoperatively and followed-up at first, third, and sixth weeks.
RESULTS
Mean SIA was less in group 1 at all the follow-up visits which was not statistically significant (P value - 0.507 (at week 1), 0.626 (at week 3), and 0.312 (at week 6). Mean SIA decreased from week 1 to week 6 in both the groups. Both the groups showed an increase in SIA with the increase in the hardness of cataract. Posterior keratometry (k1 and k2) showed statistically significant steepening in the first postoperative week, followed by gradual flattening which continued till the sixth week postoperatively. Posterior astigmatism increased in both the groups at week 1 (not statistically significant). Thereafter, it decreases and does not change significantly after 3 weeks. Pachymetry increased significantly (P value < 0.001 in both the groups) in the first week in both the groups and thereafter stabilizing at 3 weeks.
CONCLUSION
Reducing the incision size does not result in any significant reduction in SIA. We observed that the posterior corneal curvature majorly stabilized by 3 weeks, but some stabilization continued till 6 weeks.
Topics: Astigmatism; Cornea; Corneal Topography; Humans; Lens Implantation, Intraocular; Phacoemulsification; Prospective Studies
PubMed: 35086206
DOI: 10.4103/ijo.IJO_882_21 -
PloS One 2021In this study, we aimed to evaluate the characteristics of astigmatism preoperatively and 1 month postoperatively in patients with age-related ptosis (AP) and contact...
In this study, we aimed to evaluate the characteristics of astigmatism preoperatively and 1 month postoperatively in patients with age-related ptosis (AP) and contact lens-related ptosis (CLP), and investigate surgery-induced astigmatism (SIA) using the Jaffe vector analysis and the Cravy method. Consecutive patients who underwent blepharoptosis surgery between January 2019 and December 2019 were included. The patients were divided into AP and CLP groups. Computerized corneal topography was used to assess the magnitude and axis of corneal astigmatism. Astigmatism was classified as with-the-rule (WTR), against-the-rule (ATR), or oblique astigmatism (OA) pre- and postoperatively. SIA was calculated by vector analysis using the Cravy and Jaffe methods. The correlation between SIA and margin reflex distance (MRD) was calculated. One hundred and eight eyes from 58 patients (AP group: 85 eyes from 45 patients, CLP group: 23 eyes from 13 patients) were included. The AP group (73.8±7.6 years) was significantly older than the CLP group (47.7±6.6 years). The MRD increased significantly after treatment in both groups. The proportions of WTR, ATR, and OA were 52%, 22%, and 25%, and 86%, 9%, and 4% in the AP and CLP groups, respectively. A shift in astigmatism type was observed in 41% and 13% of patients in the AP and CLP groups, respectively. The average SIA measured using the Cravy method was 0.11±1.22 D in the AP group and -0.28±1.07 D in the CLP group (WTR astigmatism). The SIA calculated using the Jaffe method was 0.78±0.70 D in the AP group and 0.82±0.88 D in the CLP group. There was no significant correlation between SIA calculated using the Cravy and Jaffe methods and MRD. ATR was most common in age-related ptosis and WTR was most common in contact lens-related ptosis. Upper eyelid re-positioning may affect visual functions due to astigmatic changes in the short term postoperatively.
Topics: Aged; Astigmatism; Blepharoptosis; Contact Lenses; Female; Humans; Male; Middle Aged; Postoperative Complications; Visual Acuity
PubMed: 34710107
DOI: 10.1371/journal.pone.0258688 -
Indian Journal of Ophthalmology Feb 2022To compare the accuracy in astigmatism reduction by using IOLM 700 steep total keratometry (TK) axis, Berdahl and Hardten astigmatism fix, and Barrett Rx formula...
PURPOSE
To compare the accuracy in astigmatism reduction by using IOLM 700 steep total keratometry (TK) axis, Berdahl and Hardten astigmatism fix, and Barrett Rx formula following misaligned toric intraocular lens (IOL).
METHODS
Ten patients with residual refractive astigmatism due to misalignment following toric IOL implantation were included in this retrospective study. They were analyzed at days 4, 7/8, and 10/11 following primary cataract surgery on the platform of Berdahl and Hardten astigmatism fix, Barrett Rx formula, and IOLM 700 to determine the optimum axis of repositioning, and underwent IOL realignment on the steep TK axis of IOLM 700 assisted by the Callisto eye. The final outcome parameters were subjective refraction and orientation of toric IOL assessed 22 ± 1 days following repositioning surgery. These parameters were fed in the Barrett Rx formula and its vector analysis graph was utilized to determine the predicted ideal axis with the least residual astigmatism and the estimated residual astigmatism if the toric IOL was realigned according to the axis suggested by Berdahl and Hardten astigmatism fix and Barrett Rx formula.
RESULTS
Realigning the toric IOL on IOLM 700 steep TK axis along with the Callisto eye reduces the residual refractive astigmatism significantly (P = 0.003) from 2.00 ± 0.78 D to 0.18 ± 0.12 D (90.5 ± 7.6%) in comparison to the estimated 0.57 ± 0.31 D (68.4 ± 21.9%) by Berdahl and Hardten astigmatism fix and 0.61 ± 0.33 D (66.4 ± 23.5%) by Barrett Rx formula.
CONCLUSION
Realigning the misaligned toric IOL on the IOLM 700 steep TK axis gives a better reduction in the residual refractive astigmatism in comparison to Berdahl and Hardten astigmatism fix and Barrett Rx formula.
Topics: Astigmatism; Humans; Lens Implantation, Intraocular; Lenses, Intraocular; Phacoemulsification; Refraction, Ocular; Retrospective Studies; Visual Acuity
PubMed: 35086207
DOI: 10.4103/ijo.IJO_1760_21 -
Investigative Ophthalmology & Visual... Aug 2021To quantify astigmatism-related meridional anisotropy in visual resolution at central, nasal, and inferior visual fields.
PURPOSE
To quantify astigmatism-related meridional anisotropy in visual resolution at central, nasal, and inferior visual fields.
METHODS
Three groups of young adults (range, 18-30 years) with corrected-to-normal visual acuity (logMAR 0) were recruited: (1) myopic astigmats (MA): spherical-equivalent error (SE) < -0.75D, with-the-rule astigmatism ≥ 2.00D, n = 19; (2) simple myopes (SM): SE < -0.75D, astigmatism ≤ 0.50D, n = 20; and (3) emmetropes (EM): SE ± 0.50D, astigmatism ≤ 0.50D, n = 14. Resolution acuity was measured for the horizontal and vertical gratings at central and peripheral visual fields (eccentricity: 15°) using a 3-down 1-up staircase paradigm. On- and off-axis refractive errors were corrected by ophthalmic lenses.
RESULTS
The MA group exhibited meridional anisotropy preferring vertical gratings. At the central field, the MA group had better resolution acuity for vertical than horizontal gratings, and their resolution acuity for horizontal gratings was significantly worse than the SM and EM groups. At peripheral visual fields, both the SM and EM groups showed better resolution acuity for the radial (i.e., nasal field: horizontal gratings; inferior field: vertical gratings) than tangential orientation. However, the MA group tended to have better resolution acuity for the tangential orientation (i.e., vertical gratings), and their resolution acuity for horizontal gratings was significantly lower than the SM and EM groups at the nasal field. No significant differences were found in the inferior field among the three groups.
CONCLUSIONS
This study provided evidence of astigmatism-related meridional anisotropy at the fovea and nasal visual fields, underscoring the significant impact of astigmatism on orientation-dependent visual functions.
Topics: Adolescent; Adult; Anisotropy; Astigmatism; Emmetropia; Female; Fovea Centralis; Humans; Male; Myopia; Refraction, Ocular; Visual Acuity; Visual Fields; Young Adult
PubMed: 34379095
DOI: 10.1167/iovs.62.10.11 -
Eye & Contact Lens Feb 2021Fitting philosophies for toric orthokeratology are based on elevation or corneal astigmatism, but it is unclear which is more effective. The purpose of this analysis was...
OBJECTIVES
Fitting philosophies for toric orthokeratology are based on elevation or corneal astigmatism, but it is unclear which is more effective. The purpose of this analysis was to further understand corneal shape and the relationship between peripheral elevation and central astigmatism in moderate-to-high astigmats.
METHODS
Corneal tomography was measured three times on the right eyes of 25 moderate-to-high refractive myopic astigmatic adults. Corneal astigmatism and elevation were calculated at 4-, 6-, and 8-mm chords. Subjects were fitted with toric orthokeratology lenses following the manufacturer's guidelines based on elevation. Twenty subjects completed 10 days of wear. A masked examiner assessed movement and centration via slitlamp videos and quantified treatment zone and decentration from tangential power difference tomography maps. Correlations between variables were assessed.
RESULTS
Average corneal astigmatism was 2.20±0.70 DC and peripheral elevation was 50.88±18.92 μm and they were strongly correlated (4 mm R2=0.96, 6 mm R2=0.92, 8 mm R2=0.86, all P<0.001). Each diopter of astigmatism equated to 25 μm of elevation at an 8-mm chord. Via slitlamp, average treatment zone area was 12.73±4.62 mm2 and 13 lenses decentered. From tomography, average treatment zone area was 7.16±2.56 mm2 and 17 were decentered. Tomography treatment zone area was negatively correlated with central corneal astigmatism (R2=0.60) and elevation at an 8-mm chord (R2=0.64, both P<0.001).
CONCLUSIONS
For tomography images, central corneal astigmatism was highly correlated with peripheral elevation and may be a more expedient measure for clinical use. Treatment area decreased as corneal astigmatism and elevation increased.
Topics: Adult; Astigmatism; Cornea; Corneal Topography; Humans; Lenses, Intraocular; Myopia; Refraction, Ocular
PubMed: 32568927
DOI: 10.1097/ICL.0000000000000721