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Journal of Cataract and Refractive... Aug 2015To reevaluate the analysis of the correction of astigmatism.
PURPOSE
To reevaluate the analysis of the correction of astigmatism.
SETTING
Academia, industry, and private practice.
DESIGN
Evaluation of diagnostic test or technology.
METHODS
Astigmatic refractive surgery outcomes are based on vector methods, including the correction index (also known as the correction ratio), which is the ratio of the surgically induced astigmatism to the target induced astigmatism (TIA). Mean correction indices substantially greater than 1 have been reported for astigmatic corrections less than 1.00 diopter (D) and as representing systematic overcorrection. We hypothesize that this reflects a limitation of the correction index rather than systematic flaws in treatments. The theoretical mathematic behavior of the correction index was analyzed, accounting for variability in astigmatism measurement. Then, the impact of cylinder measurement variability on the mean correction index was modeled. A Monte Carlo simulation was performed and calculated 10 000 values of correction index for various values of TIA. Finally, correction indices from published and unpublished studies of refractive lasers were compared with the simulations.
RESULTS
The mean correction index is always greater than 1 for the case of a perfect refractive correction; however, for astigmatic corrections less than 1.00 D, the mean correction index increases sharply because the measurement variability is similar in magnitude to TIA. Almost all previous studies show the predicted increase in the correction index for low astigmatic corrections.
CONCLUSION
The correction index is a useful vector-based metric for the evaluation of refractive procedures, but mean values greater than 1 should be anticipated for lower astigmatic treatments and do not necessarily represent systematic overcorrection.
FINANCIAL DISCLOSURE
Dr. Bullimore is a consultant to Alcon Surgical, Inc., Carl Zeiss Meditec AG, Digital Vision Systems, Essilor, Innovega, Inc., and Paragon Vision Sciences, Inc. Dr. Spooner is a consultant to Alcon Surgical, Inc., Carl Zeiss Meditec AG, Digital Vision Systems, Thru-Focus Optics LLC, and i2eyediagnostics, Ltd. Dr. Dishler is a consultant to Carl Zeiss Meditec AG and Revision Optics, Inc. Dr. Sluyterman is an employee of Carl Zeiss Meditec AG.
Topics: Astigmatism; Biometry; Computer Simulation; Cornea; Humans; Lens Implantation, Intraocular; Monte Carlo Method; Phacoemulsification; Pseudophakia; Refraction, Ocular; Visual Acuity
PubMed: 26432121
DOI: 10.1016/j.jcrs.2014.12.060 -
Journal of Cataract and Refractive... May 2019To compare the outcomes of the combination of an image-guided system and intraoperative aberrometer with the surgeon's standard of care in correcting astigmatism using... (Randomized Controlled Trial)
Randomized Controlled Trial
Correcting astigmatism at the time of cataract surgery: Toric IOLs and corneal relaxing incisions planned with an image-guidance system and intraoperative aberrometer versus manual planning and surgery.
PURPOSE
To compare the outcomes of the combination of an image-guided system and intraoperative aberrometer with the surgeon's standard of care in correcting astigmatism using toric intraocular lenses (IOLs) or corneal incisions.
SETTING
Single site in United States.
DESIGN
Prospective case series.
METHODS
Contralateral eyes of patients having uncomplicated bilateral cataract surgery and astigmatism correction were randomly assigned to Group A or Group B. Group A received the surgeon's preferred standard of care. Group B had preoperative planning using an image-guidance system (VERION), intraoperative aberrometry (ORA System with VerifEye+), and femtosecond laser-assisted cataract surgery. The primary endpoint was the residual refractive astigmatism at 3 months.
RESULTS
Thirty-eight eyes were treated with toric IOLs and 40 eyes with corneal astigmatic incisions. On average, toric IOLs resulted in almost 0.25 diopter (D) less cylinder than corneal astigmatic incisions (P < .01), with no difference between groups (P = .41). There was no statistically significant difference in the mean spherical equivalent refraction by group (P = .51). At 3 months, the IOL in 4 eyes (11%) (2 in Group A and Group B each) was more than 10 degrees of absolute orientation from the intended orientation. The mean keratometry was 0.16 D higher with the image-guided system compared with optical biometry (Lenstar). The vector difference between the 2 measurements was 0.5 D or lower in all eyes.
CONCLUSIONS
The combined use of an image-guided system and intraoperative aberrometer did not significantly improve outcomes compared with the surgeon's standard of care. Based on keratometry, there was good agreement in corneal astigmatism measurements between the image-guided system and the optical biometer.
Topics: Astigmatism; Cataract; Cornea; Corneal Pachymetry; Equipment Design; Follow-Up Studies; Humans; Lenses, Intraocular; Phacoemulsification; Prospective Studies; Prosthesis Design; Refraction, Ocular; Surgery, Computer-Assisted; Visual Acuity
PubMed: 30902431
DOI: 10.1016/j.jcrs.2018.12.002 -
BMC Ophthalmology Sep 2018Standardization for reporting medical outcomes facilitates clinical study comparisons and has a fundamental role on research reproducibility. In this context, we present...
BACKGROUND
Standardization for reporting medical outcomes facilitates clinical study comparisons and has a fundamental role on research reproducibility. In this context, we present AstigMATIC, a free standalone application for automated standardized astigmatism vector analyses in corneal and intraocular refractive surgeries. AstigMATIC uses a simple graphical user interface (GUI) and allows the simultaneous display and analysis of astigmatism magnitude and axis.
RESULTS
The software produces the four following standard graphs according to the standards of the Alpins Method; 1-Target-Induced Astigmatism Vector, 2- Surgically-Induced Astigmatism Vector, 3-Difference Vector and 4-Correction Index. Vector means with X and Y standard deviations are automatically calculated and displayed on the corresponding single-angle vector plots (0 to 180°). Data points are entered into a simplified GUI with no need for command line input. The standard graphs can be easily exported as high-resolution TIFF images for figures to use in production and presentations.
CONCLUSIONS
AstigMATIC enables the user to easily and efficiently analyze vectorial astigmatism outcomes using the standardized Alpins Method for post-surgical astigmatism.
Topics: Astigmatism; Diagnosis, Computer-Assisted; Diagnostic Techniques, Ophthalmological; Humans; Reproducibility of Results; Software
PubMed: 30241474
DOI: 10.1186/s12886-018-0920-1 -
Cornea Sep 2023The purpose of this study was to assess long-term stability and outcomes of femtosecond astigmatic keratotomy (FSAK) after treatment of high postkeratoplasty astigmatism.
PURPOSE
The purpose of this study was to assess long-term stability and outcomes of femtosecond astigmatic keratotomy (FSAK) after treatment of high postkeratoplasty astigmatism.
METHODS
This retrospective study included patients who underwent FSAK for high astigmatism (≥4 D) after penetrating keratoplasty or deep anterior lamellar keratoplasty. Main outcome measures were corneal astigmatism, uncorrected visual acuity, and best-corrected visual acuity (BCVA) at 1 month and 1, 5, and 10 years.
RESULTS
Overall, 61 eyes of 61 patients (mean age 56 ± 19 years, 54.1% male) were included in this study. Preoperative corneal astigmatism ranged from 4 to 25 D. One month after FSAK, mean corneal astigmatism was significantly reduced from 9.02 ± 3.97 D to 4.86 ± 3.10 D ( P < 0.001). Thereafter, corneal astigmatism remained stable at all visits up to 10 years ( P < 0.05 for all compared with baseline). After FSAK, there was a significant improvement in logMAR uncorrected visual acuity from 1.21 ± 0.48 to 0.87 ±0.54 ( P < 0.001) and logMAR BCVA from 1.03 ± 0.55 to 0.49 ± 0.45 ( P < 0.001) which remained stable up to 10 years. A mild reduction in BCVA improvement was seen between 1 month and 1 year.
CONCLUSIONS
Femtosecond astigmatic keratotomy was effective and stable at reducing very high magnitudes of postkeratoplasty astigmatism over the long term. The procedure also had a stable effect on visual acuity, albeit some reduction in the degree of BCVA improvement was seen over the early postoperative period.
Topics: Humans; Male; Adult; Middle Aged; Aged; Female; Keratoplasty, Penetrating; Refraction, Ocular; Astigmatism; Retrospective Studies; Corneal Topography; Cornea; Corneal Diseases; Postoperative Complications
PubMed: 35965401
DOI: 10.1097/ICO.0000000000003109 -
Journal of Cataract and Refractive... Sep 2018To compare corneal astigmatism and shape between male and female eyes in relationship to age. (Comparative Study)
Comparative Study
PURPOSE
To compare corneal astigmatism and shape between male and female eyes in relationship to age.
SETTING
Hayashi Eye Hospital, Fukuoka, Japan.
DESIGN
Prospective case series.
METHODS
Eyes of men and women in 5 age groups (40 to 49 years, 50 to 59 years, 60 to 69 years, 70 to 79 years, and ≥80 years) had videokeratographic evaluations using a Placido-Scheimpflug system. Corneal astigmatism decomposed to vertical-horizontal (J0) and oblique (J45) astigmatism components was compared between male and female eyes, and corneal shape changes were compared using videokeratography maps.
RESULTS
The study comprised 1000 eyes (100 eyes of male patients and 100 eyes of female patients in each of the 5 age groups). The mean J0 of the total and anterior cornea were significantly smaller in male eyes than in female eyes in all age groups (P ≤ .0269) with no significant difference in the J45 between sexes, indicating greater against-the-rule (ATR) astigmatism in male eyes. The mean J0 of the posterior cornea did not differ significantly between sexes except in the 50 to 59 years group (P = .0105). The ATR astigmatic change per decade did not differ significantly between men and women. Videokeratography maps revealed that the total and anterior corneal shape changed to ATR astigmatism with age in both sexes, and that this ATR change began at a younger age in male eyes than in female eyes. The posterior corneal shape did not differ between sexes at any age.
CONCLUSION
Against-the-rule corneal astigmatism was greater and the ATR astigmatic change with age began earlier in the male eyes than in the female eyes, suggesting that target astigmatism should be determined separately for men and women when performing astigmatism correction.
Topics: Adult; Aged; Aged, 80 and over; Aging; Astigmatism; Cornea; Corneal Topography; Female; Humans; Male; Middle Aged; Prospective Studies; Refraction, Ocular; Sex Factors; Visual Acuity
PubMed: 30077353
DOI: 10.1016/j.jcrs.2018.06.020 -
The British Journal of Ophthalmology Jul 2023To examine whether long-term corneal astigmatic changes after stabilisation of surgically induced astigmatism (SIA) following cataract surgery differ among eyes having...
AIMS
To examine whether long-term corneal astigmatic changes after stabilisation of surgically induced astigmatism (SIA) following cataract surgery differ among eyes having against-the-rule (ATR), with-the-rule (WTR), and oblique astigmatism.
METHODS
Anterior corneal astigmatism of 390 eyes in 390 patients (130 eyes each having ATR, WTR and oblique astigmatism) who underwent phacoemulsification with a horizontal clear corneal or scleral incision and 390 eyes in 390 control patients without surgery were examined using an auto-keratometer on the day that SIA stabilised (baseline) and at ≥8 years post baseline. Changes in corneal astigmatism during the ≥8 years post baseline were decomposed to vertical/horizontal (Rx) and oblique astigmatism components (Ry), and compared among baseline types of astigmatism and between eyes with and without surgery.
RESULTS
The mean corneal astigmatic changes (Rx and Ry) showed an ATR shift of 0.2-0.3 D during the ≥8 years post baseline, which did not differ significantly among the ATR, WTR and oblique astigmatism groups in eyes with and without surgery. In the ATR, WTR and oblique groups, the mean Rx and Ry did not differ significantly between eyes with and without surgery. Double angle plots revealed an equivalent degree of ATR change in the ATR, WTR and oblique groups between eyes with and without surgery.
CONCLUSION
Long-term corneal astigmatic changes towards ATR astigmatism occurred to a similar extent in eyes having ATR, WTR, oblique astigmatism and were comparable between eyes with and without surgery, suggesting that astigmatism type need not be considered when planning astigmatism correction.
Topics: Humans; Astigmatism; Retrospective Studies; Cataract Extraction; Phacoemulsification; Cornea; Corneal Diseases; Cataract; Corneal Topography
PubMed: 35301217
DOI: 10.1136/bjophthalmol-2021-321026 -
Journal of Optometry 2017To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians)... (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes.
METHODS
The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength).
RESULTS
LogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope of the line dependent on the accommodative demand in each type of astigmatism. However, in each case, we found no statistically significant differences between the three axes investigated (0°, 45°, 90°). Non-statistically significant differences were found either for the VA achieved with spherical myopic defocus (MD) and mixed astigmatism (MA). VA with simple hyperopic astigmatism (SHA) was higher than with simple myopic astigmatism (SMA), however, in this case non conclusive results were obtained in terms of statistical significance. The VA achieved with imposed compound hyperopic astigmatism (CHA) was highly influenced by the eye's accommodative response.
CONCLUSIONS
VA is correlated with the blur strength in a different way for each type of astigmatism, depending on the accommodative demand. VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation.
Topics: Accommodation, Ocular; Adult; Astigmatism; Eyeglasses; Female; Humans; Male; Reading; Visual Acuity
PubMed: 27639497
DOI: 10.1016/j.optom.2016.07.003 -
Optometry and Vision Science : Official... Apr 2015Driving is a vision-based activity of daily living that impacts safety. Because visual disruption can compromise driving safety, contact lens wearers with astigmatism... (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
Driving is a vision-based activity of daily living that impacts safety. Because visual disruption can compromise driving safety, contact lens wearers with astigmatism may pose a driving safety risk if they experience residual blur from spherical lenses that do not correct their astigmatism or if they experience blur from toric lenses that rotate excessively. Given that toric lens stabilization systems are continually improving, this preliminary study tested the hypothesis that astigmats wearing toric contact lenses, compared with spherical lenses, would exhibit better overall driving performance and driving-specific visual abilities.
METHODS
A within-subject, single-blind, crossover, randomized design was used to evaluate driving performance in 11 young adults with astigmatism (-0.75 to -1.75 diopters cylinder). Each participant drove a highly immersive, virtual reality driving simulator (210 degrees field of view) with (1) no correction, (2) spherical contact lens correction (ACUVUE MOIST), and (3) toric contact lens correction (ACUVUE MOIST for Astigmatism). Tactical driving skills such as steering, speed management, and braking, as well as operational driving abilities such as visual acuity, contrast sensitivity, and foot and arm reaction time, were quantified.
RESULTS
There was a main effect for type of correction on driving performance (p = 0.05). Correction with toric lenses resulted in significantly safer tactical driving performance than no correction (p < 0.05), whereas correction with spherical lenses did not differ in driving safety from no correction (p = 0.118). Operational tests differentiated corrected from uncorrected performance for both spherical (p = 0.008) and toric (p = 0.011) lenses, but they were not sensitive enough to differentiate toric from spherical lens conditions.
CONCLUSIONS
Given previous research showing that deficits in these tactical skills are predictive of future real-world collisions, these preliminary data suggest that correcting low to moderate astigmatism with toric lenses may be important to driving safety. Their merits relative to spherical lens correction require further investigation.
Topics: Adult; Astigmatism; Automobile Driving; Computer Simulation; Contact Lenses, Hydrophilic; Contrast Sensitivity; Cross-Over Studies; Female; Humans; Male; Myopia; Psychomotor Performance; Single-Blind Method; Visual Acuity; Young Adult
PubMed: 25946099
DOI: 10.1097/OPX.0000000000000554 -
European Journal of Ophthalmology May 2017To evaluate the effect of astigmatism axis on uncorrected distance visual acuity (UDVA) in emmetropic eyes that underwent laser refractive surgery.
PURPOSE
To evaluate the effect of astigmatism axis on uncorrected distance visual acuity (UDVA) in emmetropic eyes that underwent laser refractive surgery.
METHODS
This retrospective study included patients who underwent laser in situ keratomileusis or photorefractive keratectomy between January 2000 and December 2015 at the Care-Vision Laser Centers, Tel Aviv, Israel. Eyes with a 3-month postoperative spherical equivalent between -0.5 D and 0.5 D were included in this study. Eyes with ocular comorbidities and planned ametropia were excluded. Study eyes were divided into 3 groups according to the steep astigmatic axis: with the rule (WTR) (60-120), oblique (31-59 or 121-149), and against the rule (ATR) (0-30 or 150-180). The UDVA of these 3 groups was compared. The oblique group was divided into oblique ATR and oblique WTR, which were compared with each other.
RESULTS
A total of 17,416 consecutive eyes of 8,708 patients were studied. The WTR eyes (n = 10,651) had significantly better UDVA (logMAR 0.01 ± 0.08) than the oblique (n = 3,141, logMAR 0.02 ± 0.09) and ATR eyes (n = 3,624, logMAR 0.02 ± 0.10) (p<0.001). The oblique WTR group had significantly better UDVA than the oblique ATR group (p<0.001). The UDVA of the oblique and ATR groups was similar. Stepwise multiple regression analysis showed that the group accounted for 15% of the UDVA variance (p = 0.04).
CONCLUSIONS
The astigmatic axis has a small but significant effect on UDVA in emmetropic eyes; WTR was better than oblique and ATR astigmatism. Therefore, when correcting astigmatism, it may be preferable to err towards WTR astigmatism.
Topics: Adolescent; Adult; Aged; Astigmatism; Female; Humans; Male; Middle Aged; Refraction, Ocular; Refractive Surgical Procedures; Retrospective Studies; Visual Acuity; Young Adult
PubMed: 27739560
DOI: 10.5301/ejo.5000890 -
Lasers in Medical Science Mar 2019To evaluate the outcome after astigmatic correction of small incision lenticule extraction (SMILE) and to compare the refractive results of right eyes with left eyes....
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 < 0.50 D 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.
Topics: Adult; Astigmatism; Female; Germany; Humans; Male; Myopia; Postoperative Period; Refraction, Ocular; Retrospective Studies; Surgical Wound; Visual Acuity; Young Adult
PubMed: 30105485
DOI: 10.1007/s10103-018-2591-9