Changes In Corneal Astigmatism Research Articles

Clinical observations of EVO-ICL implantation and changes in corneal astigmatism using a modified technique

BackgroundImplantable collamer lens (ICL) surgery techniques are constantly progressing. The purpose of this study was to investigate the application effect of the modified technique and its impact on the change in corneal astigmatism in EVO-ICL surgery.MethodsThe analysis of retrospective cohort data included 153 eyes of 81 patients with myopia from July 2018 to May 2020. An EVO-ICL was inserted by modified surgical skills, including a single 3.0 mm corneal incision and no ophthalmic viscosurgical device (OVD) before the insertion of the ICL (modified technique group: 41 cases, 80 eyes) and standard procedure (standard technique group: 40 cases, 73 eyes). Early postoperative intraocular pressure (IOP) was monitored at 2 and 24 h. IOP, corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), vault, and anterior chamber depth (ACD) were measured 1, 6, and 12 months following the initial examination. The corneal endothelial cell density (ECD) was monitored at 6 and 12 months after the operation. Surgically induced astigmatism (SIA) in the total, anterior, and posterior corneal surfaces was analysed 1 month after the operation.ResultsNo serious complications were detected. The two groups had no difference in visual outcomes, ICL vaults, or ACD at any time point (P > 0.05). Two hours postoperatively, IOP was significantly lower in the modified technique group (16.22 ± 2.22 vs. 18.37 ± 1.92 mmHg, P < 0.05) than in the standard technique group. IOP decreased gradually after 24 h to preoperative levels. The postoperative IOP remained stable over a 12-month period. The ECD at 6 and 12 months was not significantly different between the groups (P > 0.05). SIA in the total, anterior, and posterior corneal surfaces were assumed to have no clinically meaningful differences between groups at one month after operation (P > 0.05).ConclusionsThe modified technique is efficient and safe, producing comparable visual and structural outcomes without adversely affecting ECD, and reduces fluctuations in IOP at the early postoperative stages. The auxiliary incision in the standard technique does not increase corneal SIA, which is also a factor to consider for inexperienced surgeons.

Changes in Corneal Astigmatism after Closing Clear Corneal Incision by Simple Hydration Undergoing Phacoemulsification at the Department of Ophthalmology JPMC

Purpose: To determine the mean changes of corneal astigmatism after closing clear corneal incision by simple hydration undergoing phacoemulsification in the eye department of a tertiary care hospital. Methodology: This was a Quasi experimental study conducted at the department of Ophthalmology, Jinnah Postgraduate Medical Center, Karachi, from 30th October 2020 to 29th April 2021. Total 100 patients who underwent phacoemulsification surgery for cataract were included. Changes of astigmatism were measured with Auto-refractometer. Fundus examination was done using +90D lens with a slit lamp. Mean changes in corneal astigmatism were calculated. Pre and post operatively change in astigmatism was compared using paired t-test. Stratification was done. P value ≤0.05 was considered as statistically significant. Results: Mean age was 43.47±11.13 years. There were 54% male and 46% female patients. Mean change of corneal astigmatism was 0.23±0.44 diopter. Mean corneal astigmatism, preoperatively, after 1 week and after 1 month were 1.05±0.05 diopter, 0.69±0.34 diopter and 1.28±0.44 diopter respectively. Highly significant mean difference of corneal astigmatism was observed between preoperatively and after 1 week, preoperatively and after 1 month and also observed between 1 week and 1 month. Conclusion: Closing clear corneal incision by simple hydration undergoing phacoemulsification was found an effective technique for treatment of corneal astigmatism. Keywords: Mean Changes, Corneal Astigmatism, Closing Clear Corneal Incision, Simple Hydration, Phacoemulsification

Predictors of Femtosecond Laser–Assisted Arcuate Keratotomy Efficacy for Astigmatism Correction in Cataract Surgery

To evaluate the predictors related to the efficacy of epithelium- and Bowman membrane-penetrating femtosecond laser-assisted arcuate keratotomy (FSAK) in the treatment of preoperative astigmatism in patients with cataracts and to clarify the predictive role of the incision-to-limbus distance. This retrospective study included patients who underwent femtosecond laser-assisted cataract surgery combined with FSAK using the LenSX platform (Alcon Laboratories, Inc) at Beijing Aier-Intech Eye Hospital from March 2017 to December 2021. The Lenstar LS900 (Haag-Streit, Inc) was used to measure the horizontal corneal diameter, and ImageJ software (National Institutes of Health) was used to measure the vertical corneal diameter and incision-to-limbus distance. Finally, the measured values were converted. Changes in corneal astigmatism before and 3 months after surgery were analyzed using Alpins vector analysis. Correlation analysis and regression analysis were used to evaluate the factors associated with surgically induced astigmatism (SIA) in preoperative ocular biometric parameters. The study included 94 eyes of 94 patients. The mean target induced astigmatism was 1.36 ± 0.44 diopters (D), SIA was 0.82 ± 0.43 D, and mean difference vector was 0.70 ± 0.40 D. Pearson correlation analysis and univariate regression analysis showed that preoperative corneal astigmatism, arcuate keratotomy arc length, incision-to-limbus distance, and astigmatism type were significant predictors of SIA. Multiple variable regression analysis included parameters such as age, arcuate keratotomy arc length, and incision-to-limbus distance and established a multiple regression model of SIA (all P < .01). The incision-to-limbus distance was a significant independent predictor of SIA, and inclusion of this parameter may further improve the accuracy of the nomogram. [J Refract Surg. 2022;38(8):480-486.].

Comparison study between Pilocarpine and Tropicamide drops on corneal topography and their effect on IL-6 and TNF-α levels in tear

Corneal stability is essential for contact lenses and refractive surgery. It seems that paralyzing eye drops or expansion of the ciliary muscle affect the radius of curvature and the strength of the cornea, and this effect is to increase the strength of the cornea during muscle spasm and decrease it in the relaxed state of the muscle. On the other hand, different factors (such as contact lens wear, ocular surface disorders, trauma, dry eye, and immunosuppression) could alter the immune defense mechanisms of the outer eye and permit microorganisms to invade the cornea. Therefore, the present study compared Pilocarpine and tropicamide drop on corneal topography and their effect on IL-6 and TNF-α levels in tear. This prospective study was performed on sixty normal and healthy eyes of sixty volunteers with a mean age of 38.19 years and without any ocular pathology. Volunteers were divided into two groups of thirty. In the first group, corneal topography of both eyes was measured before and 30 minutes after instillation of topical tropicamide 1% in only one eye. The other eye was the control eye, and no drop was given. The same routine was performed in the second group, except that subject received one drop of Pilocarpine 2% in one eye. Statistical comparison between groups for the central corneal power, corneal radius, and corneal astigmatism was performed using paired t-test. IL-6 and TNF-α levels in tear were analyzed using two Luminex commercial assays with Bio-Plex 200TM System (Bio-Rad, Hercules, California, USA). In group 1, no significant changes were found in corneal radius, power, and astigmatism. However, in group 2 subjects who received pilocarpine eye drops, the mean corneal radius value decreased significantly by 0.05 mm. The mean corneal power increased by +0.32 D. There was no significant difference change in corneal astigmatism in both groups. Evaluation of IL-6 levels in tears showed a significant difference between the control and treatment groups (P = 0.041). But no significant difference was observed between the Pilocarpine and the Tropicamide groups (P = 0.761). Evaluation of TNF-α level in tears also showed no significant difference between these groups (P = 0.088). Pilocarpine induced ciliary muscle contraction, which may cause pressure on the corneal limbus and scleral spur, resulting in changes in corneal curvature. But tropicamide eye drop did not affect corneal radius and other corneal parameters, and corneal topography can be carried out after the installation of tropicamide eye drop.

Comparison of Long-Term Corneal Astigmatic Changes After Cataract Surgery in Eyes With Superior or Horizontal Clear Corneal Incisions

To compare long-term corneal astigmatic changes after stabilization of surgically induced astigmatism (SIA) subsequent to phacoemulsification between eyes that underwent superior clear corneal incision (CCI) or horizontal CCI. Retrospective, comparative case series. We examined the anterior corneal astigmatism of eyes that underwent a 2.4-mm superior CCI (superior CCI group, n=43) or horizontal CCI (horizontal CCI group, n=43) preoperatively, on the postoperative day that SIA stabilized (baseline), and at ≥7 years post-baseline using an autokeratometer. Corneal astigmatic changes from baseline to ≥7 years post-baseline (mean duration 8.74 years in the superior CCI group and 9.05 years in the horizontal CCI group) were decomposed to vertical/horizontal (Rx) and oblique astigmatic change components (Ry) and were compared between the 2 groups. The mean corneal astigmatism components changed significantly toward against-the-rule (ATR) astigmatism in the superior CCI group and with-the-rule astigmatism in the horizontal CCI group within 6 months postoperatively. After stabilization of the SIA, both groups showed a significant increase in the mean Rx and no significant change in the mean Ry over approximately 9 years, indicating a long-term ATR shift. The mean changes in the Rx and Ry did not differ significantly between the superior and horizontal CCI groups. Double-angle plots revealed a similar degree of ATR shift between the 2 groups over the 9 years. After stabilization of the SIA, a similar degree of ATR change occurred subsequent to superior and horizontal CCIs over approximately 9 years, suggesting that CCI direction does not affect long-term astigmatic changes.

Factors associated with corneal astigmatism change after ptosis surgery.

To evaluate the predictive factors of postoperative corneal astigmatism change in ptosis patients who underwent ptosis surgical repair. Patients who underwent levator resection at Oculoplastic service of the Department of Ophthalmology, Naresuan University Hospital, Thailand between September 2017 and August 2019 were retrospectively evaluated. Changes in degree and axis of corneal astigmatism after ptosis surgery were compared based on patient factors consisting of age at operation, sex, preoperative margin-reflex distance (MRD) 1, and preoperative degree and axis of corneal astigmatism. Forty-two eyes of 28 patients were included in the study. Wilcoxon signed ranks test showed a significant postoperative corneal astigmatism change only in a subgroup of eyes with preoperative astigmatism of ≥1.5 diopters (D; P=0.006). Furthermore, 72.2% (13/18) of the eyes with preoperative astigmatism of ≥1.5 D showed a reduction of astigmatism after eyelid surgery, with the mean astigmatic change of 0.65 D. Majority of preoperative eyes demonstrated with-the-rule astigmatism pattern (45.2%), of which 57.9% showed a reduced degree of astigmatism. In patients undergoing ptosis surgery, the data demonstrate for the first time the association between postoperative corneal astigmatism change and a preoperative corneal astigmatism of ≥1.5 D. Thus, we encourage considering severity of corneal astigmatism prior to cataract or refractive surgery planning in ptosis patients, especially with toric-intraocular lens, to avoid the possibility of calculation error.

Efficacy of scleral imbrication on all quadrants in enucleated pig eyes.

To evaluate the changes in axial length (AL) and corneal astigmatism induced by scleral imbrication on all quadrants in pig eyes. Experimental study METHODS: We produced scleral imbrications either on all quadrants or on 2 consecutive quadrants of 5 enucleated pig eyes. Scleral imbrications 8mm wide were made at 8mm from the limbus on each quadrant. We determined the AL using an electronic caliper and the corneal astigmatism using a keratometer before and after the 2 types of scleral imbrications and compared the changes in ocular AL and corneal astigmatism induced by the 2 surgical procedures. The AL reduction after the scleral imbrication on all quadrants (3.96 ± 0.56mm) was larger than that on 2 quadrants (2.39 ± 0.41mm) (P = .001). The change in corneal astigmatism induced by imbrication on all quadrants (2.98 ± 1.96 D) was less than that on 2 quadrants (5.95 ± 2.04 D) (P < .029). Scleral imbrication on all quadrants induced a shorter AL and less corneal astigmatism than did a standard scleral imbrication on 2 quadrants. Therefore, the former could be a more effective operation for retinal disorders associated with high myopia, including macular hole retinal detachment and myopic foveoschisis.

Surgically induced astigmatism after cataract surgery – a vector analysis

Background: Surgically induced astigmatism (SIA) has been widely discussed in the literature as the change in corneal astigmatism resulting from corneal incision. The purpose of this study was to investigate the change in corneal refractive power preoperative to postoperative using a vector analysis of keratometry, total keratometry, and corneal back surface data from a modern optical biometer Methods: The analysis was based on a dataset of 122 eyes of 122 patients with preoperative and 1 month postoperative measurements performed with the IOLMaster 700 biometer from 1 clinical centre and a standardised surgical technique involving a corneal 2.5 mm 45°-incision made from the superior direction. Keratometry, total keratometry and corneal back surface data were processed in 3 vector components (spherical equivalent power SEQ and astigmatism considered in 0°/90° (C0°) and in 45°/135° (C45°) meridian), and the changes in corneal power vectors were analysed, comparing preoperative to postoperative values. Results: The mean corneal power of total keratometry reduced slightly after cataract surgery (-0.05 dpt), resulting mostly from a decrease in back surface power (-0.04 dpt). The astigmatism vector component C0° of total keratometry reduced by -0.28 dpt, mostly due to a decrease at the corneal front surface (-0.26 dpt). With the corneal incision at 12 o’clock position this flattening in the 90° meridian refers to a SIA of around ¼ dpt. The change in C0° and the C45° astigmatic vector components for both keratometry and total keratometry show a large variation ranging between 0.24 and 0.33 dpt (standard deviations), indicating a poor predictability of the change in astigmatism due to cataract surgery. Conclusion: Cataract surgery locally flattens the cornea in the incision meridian. This flattening shows a large individual variation and therefore a poor predictability. Our study indicates that SIA in modern cataract surgery with standardised corneal incision is in a range of 1/4 dpt.

Comparison of long-term astigmatic changes following cataract surgery among types of corneal astigmatism

AimsTo 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.MethodsAnterior corneal astigmatism...

Comparing Changes in Corneal Astigmatism Using Scheimpflug Camera after Epiblepharon Correction Surgery

Purpose: To evaluate the changes in corneal astigmatism before and after epiblepharon correction surgery with a Scheimpflug camera.Methods: From April, 2019, to June, 2020, 48 eyes of 24 patients underwent epiblepharon correction surgery. The patients were divided into two subgroups by age and their best corrected visual acuity (BCVA) and corneal anterior and posterior astigmatism were compared before and after correction surgery.Results: There was no difference in BCVA after the correction surgery. To assess the changes in the keratometric value and astigmatism after epiblepharon surgery, a Scheimpflug camera was used. The anterior flat and mean keratometry changed from 42.10 ± 1.46 to 42.43 ± 1.10 D (p = 0.035) and from 42.97 ± 1.26 to 43.21 ± 1.15 D (p = 0.012), respectively, while the posterior corneal astigmatism changed from 0.44 ± 0.31 to 0.35 ± 0.17 D (p = 0.047). There were no significant changes in steep keratometry (p = 0.191) or anterior corneal astigmatism (p = 0.126).Conclusions: There were significant changes after epiblepharon correction surgery in anterior keratometry reading and posterior corneal astigmatism.

Should Artificial Tears Be Used During the Preoperative Assessment of Toric IOLs Before Age-Related Cataract Surgery? The TORIDE Study.

To assess the impact of the use of artificial tears during the preoperative work-up performed before age-related cataract surgery, when a toric intraocular lens (IOL) was indicated. This was a monocentric prospective study assessing 73 eyes of 51 patients, included consecutively after a preoperative work-up performed without artificial tears (no artificial tears group), when a toric IOL was indicated. Each included patient underwent a second series of examinations: biometry using the IOLMaster 700 (Carl Zeiss Meditec AG) and topography using the OPD-Scan II (Nidek), 1 minute after artificial tears instillation (artificial tears group; hyaluronate de sodium 0.15%, threalose 3% [Théalose; Théa]). Changes in anterior corneal astigmatism and subsequent changes in toric IOL calculation were analyzed. The error in predicted residual astigmatism was calculated. Anterior corneal astigmatism and total corneal astigmatism measured with the IOLMaster 700 were significantly modified when artificial tears were instilled before the examinations (1.51 ± 0.57 diopters [D], range: 0.75 to -3.55 vs 1.42 ± 0.63 D, range: 0.42 to 3.35 D; P = .043 and 1.59 ± 0.54 D, range: 0.87 to 3.48 vs 1.51 ± 0.59 D, range: 0.56 to 3.27 D, P = .038, respectively). This modification led to a change in IOL cylinder calculation in 43.8% of cases and to a change in implantation axis greater than 10° in 17.7% of cases. These changes were significantly greater in patients with a breakup time (BUT) less than 5 seconds (57.5% and 27.8%, with P = .009 and .029, respectively). In the subgroup of patients with a BUT of less than 5 seconds, the mean absolute error in predicted astigmatism was significantly lower after artificial tears instillation (0.48 ± 0.50 D, range: 0.00 to 2.79 vs 0.37 ± 0.25 D, range: 0.00 to 1.10 D, P = .048). Dry eye significantly impacted toric IOL calculations and should be taken into account during the preoperative assessments. Using artificial tears reduced the number of refractive errors. [J Refract Surg. 2021;37(11):759-766.].

Changes to Corneal Topography and Biometrics After PRESERFLO Microshunt Surgery for Glaucoma.

Glaucoma surgery with PRESERFLO Microshunt shows mild and transient changes in the corneal astigmatism, corneal elevation and biometrics in the early postoperative period. Posterior corneal elevation (PCE) tends to be higher in primary open angle glaucoma (POAG). The aim was to determine the changes in the corneal keratometry, astigmatism and elevation, refraction, axial length (AL) and anterior chamber depth and volume after the implantation of the PRESERFLO Microshunt in patients with POAG in the early postoperative period. Patients diagnosed with POAG who underwent an ab externo (polystyrene-block-isobutylene-block-styrene) microshunt implantation were recruited. The central corneal thickness, the intraocular pressure (IOP), best-corrected visual acuity, refraction, biometrics, and corneal topography with a Scheimpflug topographer were analyzed preoperatively and 24 hours, 1 week, 1 month, and 3 months after surgery. A total of 30 eyes of 29 patients were included. In 24 eyes the device was implanted as a stand-alone procedure and in 6 eyes it was combined with cataract surgery. The results were analyzed separately. The IOP decreased from 21.8±5.2 and 16.5±1.5 mm Hg at baseline to 10.9±1.8 and 10.1±1.1 mm Hg at 3 months in the noncombined and combined groups (P<0.01). The anterior surface astigmatism, posterior surface astigmatism, and total corneal astigmatism increased in each group 0.4±0.3/0.2±1.0 D, 0.08±0.1/0.03±0.1 D and 0.4±0.3/0.2±0.9 D, respectively, at 3 months. The anterior corneal elevation and PCE (ACE max, ACE min, PCE max) increased in the first week (P=0.01) with no significant changes at 3 months in the noncombined group. The changes observed in the combined group were not significant. The AL decreased to 0.13±0.23 and 0.2±0.07 mm in each group (P=0.01). There was a significant correlation between the IOP and the maximum elevation of the posterior surface of the cornea at the preoperative examination (r=0.93, P=0.02). The PRESERFLO Microshunt implant for glaucoma surgery induces mild and transient changes in corneal astigmatism, AL and anterior chamber depth in the early postoperative period.

Five-year results of a prospective, randomised, contralateral eye trial of corneal crosslinking for keratoconus.

Few studies have evaluated corneal crosslinking (CXL) in a prospective, randomised fashion. This study aimed to determine the efficacy and safety of CXL to reduce the progression of keratoconus. Prospective, unmasked, randomised, contralateral eye controlled trial at a tertiary eye centre. Individuals with bilateral progressive keratoconus. One eye from each subject was randomised to CXL and the contralateral, untreated eye acted as the control. change in maximum keratometry. uncorrected distance visual acuity, spectacle corrected distance visual acuity, spherical equivalent refraction, simulated keratometry, corneal astigmatism, minimum pachymetry and complications. Thirty-eight individuals (mean age 21.1 ± 6.7 years) were enrolled with one eye treated with CXL. At 5 years, there was a mean decrease in maximum keratometry of treated eyes (-1.45 ± 2.25 D) compared to an increase among the controls (1.71 ± 2.46 D; p < 0.001). There were significant differences between the treated and control groups in the mean change of Steep SimK (-1.07 ± 1.22 vs. 0.96 ± 1.97 D; p < 0.001), Flat SimK (-0.61 ± 1.34 vs. 0.43 ± 1.12 D; p < 0.001), corneal astigmatism (-0.45 ± 1.31 vs. 0.63 ± 1.52 D; p < 0.01) and minimum pachymetry (-32.49 ± 26.32 vs. -13.57 ± 24.11 μm; p < 0.01). Complications included sterile infiltrates (n=2), microbial keratitis (n=1), persistent corneal haze/scarring at 5 years (n=4) and loss of ≥2 lines of corrected distance visual acuity (n=3). CXL is an effective and relatively safe intervention to halt or reduce the progression of keratoconus in the majority of eyes for at least 5 years.

Refractive outcome and tomographic changes after Descemet membrane endothelial keratoplasty in pseudophakic eyes with Fuchs\u2019 endothelial dystrophy

PurposeTo analyze refractive and topographic changes secondary to Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic eyes with Fuchs’ endothelial dystrophy (FED).MethodsEighty-seven pseudophakic eyes of 74 patients who underwent subsequent DMEK surgery for corneal endothelial decompensation and associated visual impairment were included. Median post-operative follow-up time was 12 months (range: 3–26 months). Main outcome measures were pre- and post-operative manifest refraction, anterior and posterior corneal astigmatism, simulated keratometry (CASimK) and Q value obtained by Scheimpflug imaging. Secondary outcome measures included corrected distance visual acuity (CDVA), central corneal densitometry, central corneal thickness, corneal volume (CV), anterior chamber volume (ACV) and anterior chamber depth (ACD).ResultsAfter DMEK surgery, mean pre-operative spherical equivalent (± SD) changed from + 0.04 ± 1.73 D to + 0.37 ± 1.30 D post-operatively (p = 0.06). CDVA, proportion of emmetropic eyes, ACV and ACD increased significantly during follow-up. There was also a significant decrease in posterior corneal astigmatism, central corneal densitometry, central corneal thickness and corneal volume over time (p = 0.001). Only anterior corneal astigmatism and simulated keratometry (CASimK) remained fairly stable after DMEK.ConclusionDespite tendencies toward a hyperopic shift, changes in SE were not significant and refraction remained overall stable in pseudophakic patients undergoing DMEK for FED. Analysis of corneal parameters by Scheimpflug imaging mainly revealed changes in posterior corneal astigmatism pointing out the relevance of posterior corneal profile changes during edema resolution after DMEK.

FIL-SSF Carlevale intraocular lens for sutureless scleral fixation: 7 recommendations from a serie of 72 cases. MICA study (Multicentric Study of the Carlevale IOL)

Lacking a standard technique, the surgical management of aphakia without capsular support remains to be optimized. The goal of this study is to analyze results for the Carlevale FIL-SSF intraocular lens and propose surgical recommendations. The P1.5 Collective performed a retrospective analysis, with a minimum follow-up of 6 months, of the records of 72 implantations of the Carlevale FIL-SSF intraocular lens, specifically designed for sutureless scleral fixation in the ciliary sulcus. The most common indication was exchange of a posterior chamber intraocular lens (70.8%). The surgery lasted a mean of 53.4minutes due to the creation of scleral flaps. The implant was damaged in 12.5% of cases. Visual acuity was improved in 83.3% of cases. The postoperative spherical equivalent was -0.3 diopters, with no change in corneal astigmatism. The implant was centered and stable in all cases. Two cases (2.8%) of cystoid macular edema were observed and resolved over six months. A number of advantages of the Carlevale FIL-SSF intraocular lens make it a safe and effective solution for correction of aphakia in the absence of capsular support. It requires a longer than usual surgical procedure, and the implant must be handled with care. From their experience, the authors propose 7 recommendations to accelerate the learning curve. In light of the results of this study, we propose the Carlevale FIL-SSF intraocular lens as the new standard for the correction of aphakia without capsular support, but other studies are necessary to determine its exact place within the heirarchy of other available techniques.

Clinical Outcomes After Femtosecond Laser-Assisted Arcuate Corneal Incisions versus Manual Incisions.

PurposeTo compare the relative effectiveness of Verion-LenSx guided femtosecond arcuate incisions and manual incisions in reducing postoperative refractive astigmatism.Patients and MethodsThis was a contralateral eye, prospective study that included subjects with 0.50 D to 1.75 D of corneal astigmatism who wanted less refractive astigmatism post cataract surgery. The surgeon used anterior keratometry and the Woodcock astigmatism nomogram for preoperative planning, while the LenSx femtosecond laser with the Verion Image Guided System was used to create all laser arcuate incisions. Manual incisions were planned using the Donnenfeld nomogram and made with a fixed-depth diamond knife. The primary outcome measure was the residual refractive astigmatism at 3 months postoperative. Secondary outcome measures included the manifest refraction, uncorrected distance visual acuity and the change in corneal astigmatism from 1 to 3 months postoperative.ResultsForty-one subjects were successfully enrolled in the study, with data from 38 subjects available at 3 months. There were no statistically significant differences in refractive astigmatism, corneal astigmatism, uncorrected distance visual acuity or manifest refraction between the Manual and Femto groups at either 1 month or 3 months. Significant changes in refractive and corneal astigmatism were noted between 1 months and 3 months. Ninety percent of eyes in both groups had ≤0.50 D of refractive astigmatism at 3 months. Two minor non-serious adverse events (full-thickness incisions of the cornea) occurred in two eyes of two different subjects in the Manual group; they were resolved without incident.ConclusionLaser arcuate incisions appear to be an effective means of reducing postoperative refractive astigmatism at the time of cataract surgery. No significant clinical differences were observed between incisions made manually and those made with an image-guided femto-second laser system. The lower number of minor adverse events experienced with the femtosecond laser system is an apparent advantage.

Predicted and Measured Changes in Posterior Corneal Astigmatism after Uncomplicated Femtosecond Assisted LASIK (FsLASIK) and Microkeratome LASIK Correction for Myopia and Low Astigmatism

ABSTRACT Purpose: To compare predicted and measured changes in astigmatism at the posterior corneal surface (PCS) after FsLASIK or LASIK. Methods: Astigmatism was measured at both corneal surfaces (PentacamTM) before and 3 months after unremarkable FFsLASIK (roup 1,n = 100) or LLASIK (roup 2,n = 100) for myopia (−7.25DS to −0.75DS) and low astigmatism (≤1.00DC). Photoablation was achieved using Schwind Amaris750STM laser (Aberration Free profile, centered on corneal vertex). Pre-and postop astigmatic data, according to subjective refraction and estimates for the corneal surfaces (over the central 3.2 mm zone), were subjected to vector analysis to calculate surgically induced astigmatism (SIA) by refraction (SIAR), at the anterior (SIAFact) and posterior corneal surfaces (SIABact). The difference vector between SIAR and SIAFact was regarded as the predicted SIA at the PCS (SIABest). Results: Reporting key findings. Mean(±sd,95%CI) SIABest and SIABact powers in group 1 were −0.52DC(±0.35,-0.56 to −0.45) and −0.11DC(±0.08,-0.13 to −0.10) in group 1, −0.35DC(0.20,-0.39 to −0.32) and −0.08DC(0.07,-0.09 to −0.06) in group 2. Differences between SIABest and SIABact were significant for powers but not axes. Significant correlations(p < .01) were revealed between (I) SIAR and SIAFact powers [Group 1, SIAR = 0.370.SIAFact-0.292,r = 0.299. Group 2, SIAR = 0.484.SIAFact-0.394,r = 0.519] but not the axes and (II) ΔC (difference between pre-[x1] and postop measured PCS astigmatic powers) and x1 [Group 1, ΔC = 0.384x1 + 0.119,r = 0.423. Group 2, ΔC = 0.135x1 + 0.047,r = 0.229,p = .022]. There was no correlation between SIABest and SIABact powers or axes. Conclusion: The changes in posterior corneal astigmatic powers according to Pentacam measurements are small and do not account for the deficit between SIAR and SIAFact after FsLASIK or LASIK.

Changes in corneal astigmatism and near heterophoria after smartphone use while walking and sitting.

Smartphone use has become an indispensable part of our daily life. The handy design and powerful processor allow smartphone users to perform diversified tasks even when walking. This study aimed to investigate and compare the optical aftereffect and vergence adaptation of using a smartphone while walking and sitting. Twenty-nine young healthy adults (aged 19 to 24 years old) with normal binocular and accommodative functions were recruited. Participants were asked to watch a movie for 30 minutes using a smartphone while either walking on a treadmill or sitting on a chair. Corneal aberrations and near heterophoria were measured before and after smartphone use by a corneal topographer and modified Thorington heterophoria test, respectively. Using the smartphone while walking induced a change in corneal H/V astigmatism, becoming 0.11±0.03 μm less negative (two-way ANOVA repeated measures, Bonferroni post-hoc test, p = 0.001). This optical aftereffect was significantly higher than after smartphone use while sitting by 0.10±0.03 μm (paired t-test, p = 0.003). Although smartphone use did not result in a significant change in near heterophoria (Bonferroni post-hoc test, p > 0.15), the vergence adaptation showed relatively more eso- or less exo-deviation by 0.79±0.36Δ in the walking than the sitting condition (paired t-test, p = 0.037). Eyecare practitioners should be cautious of the potential optical after effect and vergence adaptation after prolonged smartphone usage.

Comparative analysis of two different types of intracorneal implants in keratoconus: A corneal tomographic study.

To evaluate changes in visual acuity and corneal tomographic outcomes at 6 months after femtosecond-laser assisted implantation of two different types of intracorneal implants in keratoconus. A total of 39 keratoconus eyes implanted with two segments KeraRing (n = 22 eyes) or MyoRing (n = 17 eyes) were enrolled. Tomographic data (Pentacam system, Oculus) were analyzed and correlated with enhancement in uncorrected (UDVA) and corrected distance visual acuity (CDVA). The tomographic indices were front maximum keratometry (Kmax), corneal asphericity (Q-value) on both surfaces, average pachymetric progression indices (PPI), maximum Ambrosio relational thickness (ARTmax), Belin-Ambrósio enhanced ectasia total deviation index (BAD-D), index of surface variance (ISV), vertical asymmetry (IVA), height asymmetry (IHA) and height decentration (IHD). LogMAR UDVA and CDVA improved 2.1 (p = 0.003) and 0.7 (p = 0.074) lines with KeraRing, and 8 and 2.5 lines with MyoRing (p = 0.001). The highest and lowest mean differences in the tomographic indices between both groups were related to ISV and IHD, respectively. Changes in all indices differed significantly between two groups except for changes in front corneal astigmatism, ARTmax, ISV, IVA, IHD and IHA (p > 0.05). Correlation of changes in CDVA with changes in other parameters was statistically significant only for IHD in the KeraRing group, while changes in in UDVA were significantly correlated with changes in spherical equivalent, back Q-value, ISV, IVA, and IHA only in the MyoRing group. Both implants promote corneal shape regularization and an enhancement in UDVA in keratoconus. A considerable flattening effect and reduction in prolateness in the front corneal surface were observed with MyoRing.

Prevalence and Age-Related Changes of Corneal Astigmatism in Patients Undergoing Cataract Surgery in Northern China.

Purpose To examine the magnitude, orientation, and age-related changes of corneal astigmatism of the eyes before cataract surgery. Setting. Hebei Eye Hospital, Hebei, China. Design A clinical-based retrospective study. Results The study consisted of 5662 eyes of 5662 consecutive cataract surgery patients with a mean age of 68.26 ± 10.39 (mean ± standard deviation (SD)) years (range 40 to 97 years), and 59.86% of the patients were women. Mean corneal astigmatism was 0.98 ± 0.76 diopter (D) (range 0.00–9.61 D). Corneal astigmatism of 0.50–0.99 D was the most common range of values (30.08%), followed by 1.00–1.49 D (22.15%), ≤0.50 D (21.21%), and 1.50–1.99 D (10.28%). There was a strong U-shaped relation between corneal astigmatism and age (p for nonlinearity <.01). With the increase of age, the astigmatism axis gradually changes from with-the-rule (WTR) to against-the-rule (ATR). Moreover, in young patients with age below 65 years, WTR astigmatism was negatively correlated with age, while ATR was positively correlated with age (r = −0.11, p=.001; r = 0.10, p=.010, respectively). However, in the old patients with age above and equal to 65 years, all types of astigmatism were positively correlated with age. Conclusion This study may provide valuable and practical information to surgeons when selecting the appropriate surgical method and toric intraocular lens (IOLs).