Refractive Astigmatism Research Articles

Femtosecond laser-assisted peripheral additive stromal keratoplasty for treatment of primary corneal ectasia: Preliminary outcomes.

Purpose:To report the preliminary results of a new surgical modality for the treatment of primary corneal ectasia, which consists of implanting allogeneic corneal tissue into the peripheral corneal stroma using a femtosecond laser system or femtosecond laser-assisted peripheral allogeneic stromal additive keratoplasty or FA-PASAK.Methods:This prospective, noncomparative case series includes patients with primary corneal ectasia including keratoconus and pellucid marginal degeneration. In the operating room, one or two ring or crescent-shaped allogeneic corneal segments were prepared using a handmade double-bladed punch, which were then implanted by a specially designed device, into stromal channels in the peripheral recipient cornea fashioned with a femtosecond-laser system.Results:A total of 15 eyes of 13 patients with mean age of 31.73 years were operated. There were significant improvements in uncorrected (0.68 to 0.3 logMAR) and corrected (0.44 to 0.16 logMAR) visual acuity, mean sphere, mean spherical equivalent refractive error, and mean keratometry (steep, flat, and average). Topographic and refractive astigmatism did not change significantly. Complications included a single case of bacterial keratitis secondary to epithelial defect, which was controlled with topical antibiotics eventually leading to an uncorrected vision of 20/25 one year after surgery.Conclusion:The use of allogeneic corneal ring or crescent shape segments may be a safe and cost-effective treatment for primary corneal ectasia, whereas a nomogram is necessary to be devised for general use of the technique.

Long-term outcome of refractive errors in patients with congenital blepharoptosis who have undergone ptosis surgery

ABSTRACT Clinical Relevance Ptosis surgery induces some changes in pre-existing refractive errors and astigmatism. Monitoring refractive outcomes, planning of vision rehabilitation, and amblyopia treatment may be required following ptosis surgery. Background The few studies published on the outcomes of refractive error after ptosis surgery have been controversial. The aim of this study was to evaluate long-term outcomes of refractive error in patients with congenital blepharoptosis who had undergone ptosis surgery. Methods Patients with congenital blepharoptosis who had undergone ptosis surgery were enrolled in the study. Data on pre- and post-operative refractive errors, marginal reflex distance 1 (MRD1), and levator function were obtained. The data from fellow eyes were used as the control. Results The mean patient age of patients undergoing ptosis surgery was 19.8 ± 8 years. The mean follow-up time (time between the operation and post-up measurements) was 4.7 ± 2.1 years with a range of 2–10 years. There were no significant differences in mean refractive changes, being 0.53 ± 0.40D vs. 0.36 ± 0.45D in sphere (p = 0.19) and 0.48 ± 0.56 vs. 0.30 ± 0.23 in cylinder (p = 0.17) in operated and control eyes, respectively. Astigmatism change was, however, significantly higher in the operated eyes with an MRD1 change of ≥2.5 mm (0.84 ± 0.66 vs. 0.27 ± 0.39, p = 0.024). The changes in astigmatism in the operated eyes had a significantly positive correlation with the changes of MRD1 (r = 0.497, p = 0.019). Vectorial analysis showed no significant difference between the changes in astigmatism of the operated and control eyes (0.58 *48º vs. 0.45*53º, respectively). Conclusion Spherical power of the eyes of patients with congenital ptosis who undergo ptosis surgery does not change. A significant change in astigmatism can be anticipated in eyes with more than 2.5 mm change in MRD1. There is an association between change in astigmatism and MRD1 following ptosis surgery.

Delicate balance: the relationship between internal astigmatism and lens astigmatism

Background: Due to lack of equipment for directly measuring crystal morphology, there has been little research on lenticular astigmatism. The purpose of this study was to accurately explore the correlation between internal astigmatism and lens astigmatism in patients with ametropia. Methods: This is a cross-sectional study conducted in the Affiliated Hospital of North Sichuan Medical College, China, in September 2020. Diopter values (refractive astigmatism, RA) of patients with ametropia was recorded, and the corneal and lens biological parameters were measured by CASIA2 (corneal/anterior segment optical correlation tomography analyzer). Biometric parameters, including the total corneal astigmatism (total corneal astigmatism, TCA), anterior and posterior curvature radius of the lens (anterior curvature radius of the lens, ACL; posterior curvature radius of the lens, PCL), internal astigmatism (internal astigmatism, IA), anterior and posterior astigmatism of the lens (anterior astigmatism of the lens, AAL; posterior astigmatism of the lens, PAL) were measured. Grouping and comparisons were made according to gender and age. Results: In total, 151 participants (293 eyes) were included in the analysis. There were significant ( P<0.05) differences in the IA ( Z=-2.194, P=0.028) according to gender, but not in the other parameters. By age group, there were statistically significant differences in the TCA ( H=10.609, P=0.005), IA ( F=3.722, P=0.025), and PAL ( H=8.254, P=0.016), but not in the others. The IA was positively correlated with the age ( r=0.155, P=0.008), RA ( r=0. 534, P<0.001), AAL ( r=0.308, P<0.001), and was negatively correlated with the TCA ( r=-0.244, P<0.001). The regression equation between the IA and AAL was: Y (IA) =-0.626 +0.447 X (AAL). Conclusions: Internal astigmatism is mainly related to the anterior astigmatism of the lens, and the higher the anterior astigmatism of the lens, the higher the internal astigmatism; At the same time, internal astigmatism increases with age.

Subjective and objective clinical outcomes of a new trifocal toric intraocular lens and effect of femtosecond laser cataract surgery.

To evaluate the clinical outcomes and quality of life following implantation of PanOptix toric intraocular lens (IOL) and to compare the outcomes following femtosecond laser assisted cataract surgery (FLACS) and standard cataract surgery (SCS). This comparative retrospective study included 79 eyes of 55 patients underwent cataract or refractive lens exchange surgery between April 2017 and January 2020 in Bayindir Hospital and Kaskaloglu Eye Hospital. Corneal (CA) and refractive astigmatism (RA), uncorrected visual acuities for distant, intermediate, and near (UDVA, UIVA, and UNVA), low contrast distance visual acuity, rotational stability, defocus curves, photopic and mesopic contrast sensitivity (CS), visual function-14 (VF-14) test, presence of dysphotopsia, and need for spectacles were evaluated at postoperative third month. Outcomes were compared between FLACS and SCS group. The mean UDVA, UIVA, and UNVA were 0.05 ± 0.07, 0.08 ± 0.08, and 0.06 ± 0.07 logMAR, respectively. All patients achieved ⩾0.3 logMAR uncorrected visual acuity for all distances. UDVA was found significantly better in FLACS group (p = 0.03). All eyes had ⩽1 D of subjective postoperative RA. Defocus curve had two peaks at 0 and -1.50 D. Spectacle independence was achieved in 88.7% of patients. Photopic and mesopic CS was within normal range in all patients. The mean VF-14 score was 98 ± 2. The mean IOL axis rotation was 2.1° ± 2.3°. Only one patient reported seeing disturbing halos. This trifocal toric IOL effectively reduced refractive astigmatism and provided excellent visual outcomes with high spectacle independence, patients' satisfaction, and good rotational stability. FLACS might have an impact on optimal postoperative results.

Long-term changes in the refractive effect of a toric intraocular lens on astigmatism correction

PurposeTo examine the long-term changes in the astigmatism-correcting effect of a toric intraocular lens (IOL) after stabilization of surgically induced astigmatic changes due to cataract surgery.MethodsUnilateral eyes of 120 patients that received a toric IOL for against-the-rule (ATR) or with-the-rule (WTR) astigmatism were enrolled. Manifest refractive and anterior corneal astigmatism, and ocular residual astigmatism which is mainly derived from internal optics were examined preoperatively, at approximately 2 months postoperatively (baseline) and at 5 ~ 10 years postbaseline. The astigmatism was decomposed to vertical/horizontal (Rx) and oblique components (Ry), which was compared between baseline and 5 ~ 10 years postbaseline.ResultsIn the eyes having ATR astigmatism, the mean Rx and Ry of the manifest refractive and corneal astigmatism significantly changed toward ATR astigmatism between the baseline and 5 ~ 10 years postbaseline (p ≤ 0.0304), but those of ocular residual astigmatism did not change significantly between the 2 time points. In the eyes having WTR astigmatism, the Rx and Ry of refractive, corneal, and ocular residual astigmatism did not change significantly between the 2 time points. Double-angle plots revealed an ATR shift in refractive and corneal astigmatism and no marked change in the ocular residual astigmatism in the eyes with ATR astigmatism, and there is no change in this astigmatism in the eyes with WTR astigmatism.ConclusionThe long-term changes with age in the effect of a toric IOL significantly deteriorated due to an ATR shift of corneal astigmatism in the eyes having ATR astigmatism, while it was maintained in eyes having WTR astigmatism, suggesting that ATR astigmatism should be overcorrected.

Magnitude of astigmatism – A comparison between eyes

PurposeAstigmatism is a highly prevalent refractive error and while studies typically focus to describe the axis symmetry between eyes, little is known about the refractive symmetry. Therefore, this study determined the astigmatic power symmetry between eyes in a large clinic population. MethodsA clinical chart review was conducted at three optometric practices in the United States, the United Kingdom and Canada and subjective refraction data from 88,891 patients 14–70 years of age who presented with at least −0.25DC refractive astigmatism in at least one eye were included in the analysis. Data were obtained at these practices between January 2014 and March 2017. The overall distribution (%) and magnitude (DC) of astigmatism was determined and refractive differences between eyes were identified. ResultsThe mean age of the patients was 42.1 ± 15.9 years and included 51,685 (58%) female and 37,206 (42%) male patients. In this data pool of 177,782 eyes, 10.9% required zero astigmatic correction, while 56.2% had astigmatism of −0.25 to −0.75DC. In total 23.9% of patients presented with astigmatism of at least −0.75DC in only one eye, while the other eye had 0 to −0.50DC. Overall, the difference in astigmatism between eyes was less than −0.75DC for 82.1% of astigmatic patients. For patients who presented with astigmatism of −1.00DC in the right eye, 80.8% of them had an astigmatic prescription of −1.00 ± 0.50DC in the left eye. For an astigmatic prescription of −4.00DC in the right eye, only 40.6% of patients exhibited astigmatism of −4.00DC ± 0.50DC in the left eye. ConclusionsThe majority of patients exhibited a difference in astigmatism between eyes of less than −0.75DC, however the refractive cylinder power symmetry was significantly lower in patients with higher refractive astigmatism.

Correlation Between Keratometric and Refractive Astigmatism in Pseudophakes.

PurposeTo investigate the relationship between measured anterior, posterior, and total keratometric astigmatism and post-operative refractive astigmatism (RA) after cataract surgery.Patients and MethodsThis was a retrospective analysis of eyes that consecutively underwent pre-operative measurements of keratometric astigmatism with a swept-source optical coherence tomography (SS-OCT)-based optical biometer and dual-Scheimpflug/Placido disc corneal topographer, cataract surgery with implantation of a monofocal intraocular lens, and post-operative manifest refraction. The difference between post-operative refractive astigmatism and keratometric astigmatism measured using four different ways [Keratometry (K), Simulated Keratometry (SimK), Total Keratometry (TK), and Total Corneal Power (TCP)] was calculated.ResultsFor all 118 eyes, a smaller mean vector difference between post-operative refractive astigmatism and measured keratometric astigmatism was realized with TK (0.08 @ 151) vs TCP2 (0.30 @ 174; p < 0.0006), as well as with K (0.26 @ 173) vs SimK (0.52 @ 177; p = 0.036). The mean vector difference between post-operative refractive astigmatism and TK astigmatism was 0.31 @ 097, 0.21 @ 163, and 0.69 @ 179 in eyes with against-the rule (ATR), oblique, and with-the-rule (WTR) anterior corneal astigmatism, respectively (p < 0.0006). On the other hand, posterior corneal astigmatism did not significantly change with the orientation of anterior corneal astigmatism [0.10 @ 180 for ATR, 0.22 @ 180 for oblique, and 0.28 @ 180 for WTR (p = 0.58)].ConclusionCompared with the other measures of corneal astigmatism, total keratometric astigmatism from the SS-OCT device most closely correlated with post-operative RA. The difference between anterior corneal astigmatism and refractive astigmatism is not completely explained by the contribution from the posterior cornea. Other contributors, such as lens tilt or neuro-adaptation, may be at play.

Impact of Different Suturing Techniques on Visual Outcomes in Penetrating Keratoplasty

Purpose: This current study was conducted to investigate the influence of the variable techniques available for corneal suturing on visual outcomes in PKP. Methods: In this prospective study 40 cases underwent penetrating keratoplasty which were divided according to the technique of suturing into 2 groups each of 20 patients; first group that underwent continuous suturing and the second group underwent interrupted suturing and they were followed up along 1 year postoperative for BCVA, IOP, and both topographic & refractive astigmatism. Result: The results of the study showed comparable improvement between the two techniques regarding the BCVA, refractive astigmatism and topographic astigmatism along the 12 months of follow-up. The need for readjustment was higher in the cases underwent interrupted suturing. Conclusion: there were no significant visual or refractive differences between patients operated with continuous & interrupted suturing techniques though the patients of the interrupted technique needs more suture manipulation for favorable outcomes than that needed in continuous technique patients

Topography-Guided Trans-Epithelial No-Touch Photorefractive Keratectomy for High Irregular Astigmatism After Penetrating Keratoplasty: A Prospective 12-Months Follow-Up.

PurposeTo describe the efficacy and safety of topography-guided trans-epithelial no-touch photorefractive keratectomy (PRK) for the correction of highly irregular astigmatism after penetrating keratoplasty (PK).Patients and MethodsA prospective study was conducted on 12 eyes of 12 patients affected by highly irregular astigmatism after PK for keratoconus. Each patient underwent a single-step topography-guided trans-epithelial ablation (CIPTA®2 software, iVis Technologies). Corneal topography data as well as uncorrected (UDVA) and corrected distance visual acuity (CDVA) and spherical equivalent (SEQ) were collected preoperatively (T0) and at 1 (T1), 3 (T2) and 12 (T3) months after surgery.ResultsMean UDVA and CDVA significantly improved, respectively, from 1.22±0.17 and 0.18±0.03LogMAR at T0 to 0.63±0.17 (CI 95%, P<0.001) and 0.04±0.03LogMAR at T3 (CI 95%, P<0.001). Mean SEQ significantly decreased from −3.75±1.32 to –1.60±1.32D (CI 95%, P<0.02). Mean subjective refractive astigmatism (SRAST) and mean keratometry astigmatism (SimK) significantly decreased, respectively, from 7.83±0.98 and 8.10±1.48D to 2.83±0.98 and 5.29±1.48D (CI 95%, P<0.001). Corneal Morphological Irregularity index (CMI) significantly decreased from 62.76±7.26 µm to 23.24±7.26 µm (CI 95%, P<0.001). Apart from a single episode of graft rejection 5 days after ablation, successfully reverted with topical steroids, no other complications were noted. A mild corneal haze was observed in two eyes (16.7%) at 3 months post-PRK, and no regression was observed at 12 months.ConclusionOur study demonstrates the safety and long-term effectiveness of a trans-epithelial topography-guided ablation in the treatment of post-PK highly irregular astigmatism.

Astigmatic correction of simultaneous femtosecond laser-assisted cataract surgery (FLACS) with intrastromal arcuate keratotomy (ISAK) versus Toric intraocular Lens Impantation with conventional phacoemulsification

BackgroundTo compare the efficacies in astigmatic correction of simultaneous femtosecond laser-assisted cataract surgery (FLACS) with intrastromal arcuate keratotomy (ISAK) versus toric intraocular lens (IOL) implantation with conventional phacoemulsification in moderate astigmatism.MethodsA retrospective chart review was conducted for patients who had undergone cataract surgery by one surgeon. We identified patients with preoperative corneal astigmatism from + 0.75 to + 2.00 diopters (D) who had undergone astigmatic correction with FLACS with ISAK or toric IOL implantation with conventional phacoemulsification. We measured the visual acuity, intraocular pressure, automated keratometer, manifest refraction, and topography preoperatively and 1-day, 1-month, 3-month, and 6-month postoperatively. The vector analysis of refractive astigmatism was performed.ResultsOf a total of 48 eyes of 48 patients, 27 eyes of 27 patients had FLACS with ISAK (AK group), and 21 eyes of 21 patients had conventional cataract surgery with toric IOL implantation (toric IOL group). Refractive astigmatism was significantly decreased in both groups. The mean preoperative and 6-month postoperative refractive astigmatism were 1.85 ± 1.07 and 0.99 ± 0.51 D, respectively, in the AK group (P = 0.028), and 1.84 ± 0.81 and 0.68 ± 0.21 D, respectively, in the toric IOL group (P < 0.001). There was no significant difference in refractive astigmatism between the two groups at 6-month postoperatively (0.99 ± 0.51 vs 0.68 ± 0.21 D, P = 0.057). At 6-month postoperatively, parameters for vector analysis of refractive astigmatism showed no statistical difference between the two groups. Corneal astigmatism was significantly decreased in the AK group. Corneal astigmatism from topography and the automated keratometer were significantly lower in the AK group 6-month postoperatively compared to toric IOL group (0.94 ± 0.40 vs. 1.53 ± 0.46 D, P = 0.018 for topography; and 0.98 ± 0.69 vs. 1.37 ± 0.41 D, P = 0.032 for the automated keratometer).ConclusionsFLACS with ISAK could be an effective procedure for reducing astigmatism as well as toric IOL implantation in cataract surgery.

Clinical Outcomes of Monofocal Toric IOLs Using Digital Tracking and Intraoperative Aberrometry.

PurposeTo evaluate clinical outcomes of a toric IOL using digital tracking (DT) and intraoperative aberrometry (IA).MethodsThis was a retrospective, single surgeon study examining 151 eyes of 106 patients. Inclusion criteria were subjects who presented with visually significant cataracts (or as a candidate for clear lens extraction) and were implanted with a toric intraocular lens. Spherical equivalent prediction errors for IA and preoperative planning were calculated and compared. Preoperative and postoperative refractive data and monocular uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were also collected at 3 months postoperatively.ResultsPostoperative actual residual refractive astigmatism with IA was 0.50 D or less in 140 eyes (92.8%) and was 0.50 D or less in 88 eyes (58.3%) with back-calculations based on preoperative planning. The absolute spherical equivalent prediction error was 0.50 D or less in 135 eyes (89.4%) for IA compared to 123 eyes (85.4%) for preoperative planning. Postoperative monocular UDVA was 0.10 logMAR or better in 124 eyes (82.1%) and 0.00 logMAR or better in 90 eyes (59.6%). Postoperative CDVA was 0.10 logMAR or better in 147 eyes (97.4%) and 134 eyes (88.7%) were 0.00 logMAR or better.ConclusionThe results demonstrate that toric implantation with DT and IA can provide excellent refractive and visual outcomes.

Outcomes of toric IOL implantation guided by iris-registered femtosecond laser capsulotomy markings

To assess the accuracy and stability of iris-registered femtosecond laser-assisted anterior capsule axis markings (compensating cyclotorsion) along with refractive and visual outcomes after toric IOL implantation. This prospective case series included eyes with visually significant cataracts and regular corneal astigmatism ranging from 1.25D to 4.0D, which received FLACS and toric IOL implantation, at The Eye Institute of West Florida, Largo, Florida, USA. Preoperative iris registration was used in conjunction with a femtosecond laser platform to create cyclotorsion corrected axis marks at the capsulotomy edge to facilitate toric IOL axial alignment. Patients were examined one, seven and thirty days after surgery to assess capsulotomy marks axis, toric IOL axis along with visual and refractive outcomes. Eighteen eyes of 13 patients aged 74.35 ± 8.65years were included. Mean pre-op CDVA was 0.24 ± 0.16 LogMAR, while mean post-op UDVA was 0.09 ± 0.09 LogMAR. Mean pre-op corneal astigmatism was 1.85 ± 0.41 D, decreasing to 0.24 ± 0.41 D of refractive astigmatism postoperatively (p < 0.001). The capsular toric axis markings were visible in 100% of eyes throughout the follow-up; the mean difference between intended capsulotomy mark axis and measured capsulotomy mark axis was 1.6°, 1.7° and 1.3 o at the 1, 7 and 30 day intervals (p > 0.05), respectively. No capsule-related or any other type of complications was noted. Iris-registered femtosecond laser-assisted anterior capsule axis markings are safe and may be considered as an alternative option to the known axis marking techniques for toric IOL axial alignment at the time of cataract surgery.

Особенности диагностики и лечения ПВХРД у детей

Purpose. To identify the clinical course of the «risk-forms» of peripheral vitreochorioretinal dystrophy (PVCRD) depending on sex, age, type and degree of refraction in children, as well as to establish the characteristics of the diagnosis and treatment of PVCRD in childhood. Methods. A retrospective analysis of medical records of pediatric patients who underwent peripheral prophylactic laser retinal coagulation (PPLRC) regarding the «risk-forms» of PVHRD at the ophthalmology department of MAUZ Children’s Clinical Hospital No. 1 from 2017 to 2019 was performed. 241 childr (293 eyes) aged 7 to 17 years (mean age 14.1 ± 2.4 years) were operated. Results. PVCRD in children is asymptomatic and it is detected at the age of 7 to 17 years, regardless of gender, the peak of occurrence is 10–14 years. The most common type of PVCRD is «lattice» dystrophy. PVCRD is predominant in low degree myopia. Quite a lot of cases of PVCRD detected in emmetropic refraction, as well as in hyperopic refraction and combined astigmatism. Conclusions. A thorough examination of the periphery of the fundus is necessary in all children, regardless of age and refraction. The parameters of laser coagulation in children differ from those in adults. Given the characteristics of childhood, the success of the operation depends on the correct preoperative preparation, including psychological preparation, contact of the surgeon with the child during the operation. Key words: peripheral dystrophy; ophthalmoscopy; mydriasis; laser coagulation; children. vitreochorioretinal

Clinical Outcomes of a New Type of Continuous Intrastromal Corneal Ring for Treatment of Keratoconus.

The purpose of this study was to evaluate the efficacy and safety of implantation of a new continuous corneal ring in keratoconic corneas of an Iranian population. This study was conducted on 95 contact lens-intolerant keratoconic eyes with clear central corneas. A continuous corneal ring, annular intrastromal corneal inlay (AICI), was inserted using femtosecond laser in all cases. Patients were followed up for 1, 3, and 12 months postsurgery. Visual and subjective refractive outcomes were evaluated in each examination. Besides, keratometry and aberrometric values were recorded before and 12 months after surgery. Finally, vector analysis of refractive astigmatism was performed using the Alpins method. The uncorrected and corrected distance visual acuities improved significantly 12 months after surgery from 0.91 ± 0.39 to 0.38 ± 0.22 (P < 0 0.001) and 0.33 ± 0.21 to 0.13 ± 0.11 logMAR (P < 0.001), respectively. Moreover, spherical and cylindrical refractive components reduced from -2.52 ± 2.62 to -0.76 ± 1.78 D (P < 0.001) and -4.14 ± 1.64 to -1.91 ± 1.18 D (P < 0.001), respectively. The mean anterior keratometry had a significant reduction 12 months after AICI insertion (P< 0.001). Primary coma and spherical aberration values showed a significant increase (both, P < 0.05). Our results showed 100% safety (safety index: 1.8) and 45% efficacy (efficacy index: 1). AICI implantation seemed to be a safe and effective procedure for improving visual acuity and refractive outcomes in subjects with keratoconus.

Control of myopia using orthokeratology lenses in Scandinavian children aged 6 to 12 years. Eighteen-month data from the Danish Randomized Study: Clinical study Of Near-sightedness; TReatment with Orthokeratology Lenses (CONTROL study).

PurposeTo investigate the efficacy of myopia control defined by axial elongation and safety of orthokeratology lenses (OKL) in a Scandinavian (Danish) population.MethodsSixty Danish children aged 6–12 years with myopia ranging from 0.5 to 4.75 dioptres (D) spherical component and refractive astigmatism ≤2.5 D in both eyes were randomly assigned to either OKL or single‐vision spectacles (SVS). Study duration was 18 months. Outcome measures were axial length (AL) measured with Lenstar LS900 (Haag‐Streit, Koeniz, Switzerland) and adverse events graded with Efron Grading Scale for Contact Lens Complications.ResultsNineteen participants completed the 18‐month follow‐up in the OKL group and 28 in the SVS group. The average AL elongation in the OKL group was 0.24 mm smaller as compared to the SVS group (95% confidence interval 0.12–0.36, mixed model adjusted for baseline sex, age and AL). There were no fast progressors (>0.75 D/year) in the OKL group during the follow‐up period in contrast to 22% in the SVS group. No treatment‐requiring or vision‐threatening adverse events were observed.ConclusionOrthokeratology lenses reduced AL elongation in myopic Scandinavian children by 59%, with no treatment‐requiring or vision‐threatening adverse events. The results align with outcomes of previous clinical trials.

Comparison of Refractive and Visual Outcomes after Transepithelial Photorefractive Keratectomy (TransPRK) in Low versus Moderate Myopia

Is it possible to obtain good results in myopia of 2 or fewer diopters (D) with transepithelial photorefractive keratectomy (TransPRK) changing the optical zone and epithelium thickness? We retrospectively analyzed two groups of 296 eyes with a minimum follow-up of 4 months. Group A had 2 or less D, treated with an optical zone (OZ) 0.2 mm bigger than recommended, and a central epithelium thickness of 60 microns, and group B had 2 D to 5 D, with the recommended optical zone, and a 55-micron epithelium ablation at the center. The outcomes were not different between the two myopic ranges; the postop uncorrected distance visual acuity was 20/20 ± 4 in both groups (p = 0.2), which was −0.3 ± 0.8 lines worse than the preoperative corrected distance visual acuity in both groups (p = 0.5). The safety of the treatments resulted in a change of 0.0 ± 0.7 lines in the low myopia group, versus a gain of +0.1 ± 0.8 lines in the moderate myopia group (p = 0.1). The deviation from the intended target was −0.04 ± 0.33 D in the low myopia group and +0.07 ± 0.32 D in the moderate myopia group (p &lt; 0.0001); the postoperative spherical equivalent was 0.00 ± 0.33 D in the low myopia group and +0.10 ± 0.31 D in the moderate myopia group (p &lt; 0.0001). The postop refractive astigmatism was 0.32 ± 0.16 D in both groups (p = 0.5). In conclusion, the refractive and visual outcomes after TransPRK are comparable in low myopia changing the optical zone and epithelium thickness versus moderate myopia with standard optical zone and epithelium thickness.

Comparison of decentration, tilt and lenticular astigmatism of ıntraocular lens between sutured and sutureless scleral fixation techniques

To evaluate at six months the intraocular lens (IOL) decentration, tilt and lenticular astigmatism between foldable sutured and sutureless scleral fixation IOLs compared to conventional phacoemulsification surgery. We retrospectively reviewed records for 22 eyes with sutureless scleral fixation, 16 eyes with sutured scleral fixation and 23 eyes with conventional phacoemulsification. IOL decentration and angle of IOL tilt were compared on Scheimpflug images 6 months after surgery. Lenticular astigmatism is described as the difference between refractive and net corneal astigmatism. The angle of tilt in both meridians was significantly lower in the sutureless group than in the sutured group (P=0.008 horizontally and P=0.002 vertically). IOL decentration did not show a significant difference between the three groups in either horizontal or vertical meridians (P˃0.05). Lenticular astigmatism was significantly lower in the sutureless and control groups than in the sutured group (P=0.003 and P<0.001). In addition to being relatively quick and easy to perform, the sutureless scleral fixation technique showed superior results in terms of IOL tilt and lenticular astigmatism at the six-month follow-up compared to the sutured technique.

Delicate balance: the relationship between internal astigmatism and lens astigmatism

Background: Due to lack of equipment for directly measuring crystal morphology, there has been little research on crystal astigmatism. The purpose of this study was to accurately explore the correlation between internal astigmatism and lens astigmatism in patients with ametropia. Methods: This is a cross-sectional study conducted in the Affiliated Hospital of North Sichuan Medical College, China, in September 2020. Diopter values (refractive astigmatism, RA) of patients with ametropia was recorded, and the corneal and lens biological parameters were measured by CASIA2 (corneal/anterior segment optical correlation tomography analyzer). Biometric parameters, including the total corneal astigmatism (TCA), anterior and posterior curvature radius of the lens (ACL, PCL), internal astigmatism (IA), anterior and posterior astigmatism of the lens (AAL, PAL) were measured. Grouping and comparisons were made according to gender and age. Results: In total, 151 participants (293 eyes) were included in the analysis. There were significant (P&lt;0.05) differences in the IA (Z=-2.194, P=0.028) according to gender, but not in the other parameters. By age group, there were statistically significant differences in the TCA (H=10.609, P=0.005), IA (F=3.722, P=0.025), and PAL (H=8.254, P=0.016), but not in the others. The IA was positively correlated with the age (r=0.155, P=0.008), RA (r=0. 534, P&lt;0.001), AAL (r=0.308, P&lt;0.001), and was negatively correlated with the TCA (r=-0.244, P&lt;0.001). The regression equation between the IA and AAL was: Y (IA) =-0.626 +0.447X (AAL). Conclusions: There is a delicate balance between internal astigmatism and intraocular astigmatism. There were no significant differences in the other parameters except IA for different gender groups. For different ages, there are symbol differences in the TCA, IA and PAL, but not in the other parameters. In the analysis of IA with lens astigmatism, it was found that internal astigmatism was mainly related to AAL, but not to PAL.

Corneal collagen cross-linking (CXL) versus combined CXL and femtosecond laser-assisted intracorneal ring segment implantation for the treatment of keratoconus

Background The corneal cross-linking procedure has been proven to be an effective method to treat and stabilize keratoconus progression, but early vision rehabilitation is still needed in patients. Aim The aim was to compare the results of the combined CXL and intrastromal corneal ring segment implantation procedure to that of the cross-linking-alone procedure in terms of visual acuity, refraction, and some corneal topographic parameters in keratoconic patients. Design This was a prospective, comparative, and interventional study. Patients and methods This study was carried out on 44 keratoconic patients (60 eyes) of both sexes who ranged from 18 to 36 years. Thirty eyes were subjected to the CXL-alone procedure and 30 eyes were subjected to the combined procedure. Measurements were performed in all patients preoperatively and at 3, 6 months, and 1 year postoperatively including unaided visual acuity, best-corrected visual acuity, refractive, and topographic outcomes. Results Through the entire study period, both procedures were safe and effective in treating and stabilizing keratoconus progression. Furthermore, the combined group showed additional improvements over the CXL group for the following: UDVA at 3 months (P=0.0028), best-corrected visual acuity at 1 year (P=0.011), refractive and keratometric astigmatism at all follow-up visits and corneal asphericity at 3 months (P=0.013) and 6 months (P=0.0221) of follow-up. No severe intraoperative or postoperative complications were observed during the entire study period in either group. Conclusions The combined procedure is safe and effective for earlier improvement of visual and refractive outcomes in addition to the corneal stabilizing effect.

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.