Spherical Error Research Articles

P-19 Transepithelial PTK/limited non topoigraphic PRK combined with corneal crosslinking for keratoconus.

Data were analysed from a retrospective cohort of eyes undergoing PTK epithelial removal or limited PRK combined with corneal crosslinking. Patients undergoing PRK were either contact lens intolerant or were considering alternate surgical therapy including corneal transplantation. Data included uncorrected and best corrected vision, refraction and OCT topographic findings. Treatments were performed using a TECHNOLAS® TENEO™ 2 (Bausch & Lomb) and CXL with Avedro KXL (Glaukos) according to a modified protocol. 24 eyes were treated using combined Excimer laser PTK or limited non-topographic transepithelial PRK depending on intervention protocol with >3 month follow-up. Postoperative best corrected visual acuity improved by a mean of 0.42 LOGMAR units (SD 0.37, range 0.1 to 1.4) (p<0.005). All eyes had improvement of BCVA. Mean absolute spherical refractive error decreased by 0.56 D (SD 1.26, range -2.5 to 2) (p<0.05). Postoperative spherical error increased in a few cases (3/24, 12%) Mean absolute refractive cylinder decreased by 1.46D (SD 2.3 range -4.75 to 7) (p<0.05). Limited increase of astigmatism occurred in 2 (8,3%) cases. There were no postoperative complications noted. PTK/limited non topographic PRK combined with CXL may offer improvement to corrected visual acuity compared to CXL alone.

The Use of Intraoperative Aberrometry in Normal Eyes: An Analysis of Intraocular Lens Selection in Scenarios of Disagreement.

To compare prediction error outcomes between the Optiwave Refractive Analysis System (ORA) (Alcon Laboratories, Inc) and two modern intraocular lens (IOL) formulas (Hill-RBF2.0 [HRBF] and Barrett Universal II [BUII]), and further analyze IOL selection in scenarios of disagreement between methods. Patients with no previous history of corneal refractive surgery who underwent cataract extraction and had intraoperative aberrometry measurements between October 2016 and December 2019 were analyzed. The prediction error for the ORA, HRBF, and BUII were calculated based on the postoperative manifest refraction. Further analysis was performed evaluating prediction error for scenarios of disagreement between the three methods. After exclusions, 281 eyes were included. The mean absolute prediction errors were 0.28 diopters (D) (ORA), 0.31 D (HRBF), and 0.33 D (BUII) (P < .05). In instances when the IOL recommended by the ORA was in disagreement with what was selected preoperatively, there was no benefit when the lens recommended by the ORA was selected based on anecdotal experience. When further analyzing these instances of disagreement, selecting the ORA-recommended lens when it is higher in power results in improved refractive outcomes: the ORA resulted in more eyes within ±0.25 diopters (D) of predicted spherical error (65% ORA, 37% HRBF, 32% BUII; P = .004) and fewer hyperopic surprises (5% ORA, 15% HRBF, 24% BUII; P = .009). In normal eyes without previous corneal refractive surgery, intraoperative aberrometry is not different from to two modern preoperative IOL formulas. Placing the ORA-recommended lens when it is higher in power than that selected preoperatively results in better refractive outcomes. [J Refract Surg. 2022;38(5):304-309.].

Clinical outcomes of transepithelial photorefractive keratectomy with epithelial ablation targeting actual epithelial thickness vs default laser platform values.

To investigate the clinical outcomes of transepithelial photorefractive keratectomy (tPRK) with actual epithelial thickness vs default software values. Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran. Prospective controlled study. Patients with refractive spherical error of -1.50 to -7.00 diopters (D) and refractive astigmatism up to 4.00 D were consecutively enrolled and divided into 2 groups: group 1 undergone tPRK with actual central and peripheral epithelial thickness input in right eyes, group 2 undergone tPRK with actual central and 10 mm higher peripheral epithelial thickness in right eyes. Left eyes in both groups underwent tPRK with default protocol. Outcome measures were induced refractive error, achieved optical zone (OZ), and wasted stromal tissue. 83 patients were included in this study. Mean ± SD of induced spherical equivalent was +0.15 ± 0.39 D and +0.01 ± 0.35 D in right and left eyes of group 1 (P = .01) and +0.04 ± 0.22 D and +0.03 ± 0.23 D in right and left eyes of group 2 (P = .75), respectively. There was no statistically significant difference between wasted tissue between right and left eyes in group 1 and group 2 (P = .77 and P = .49, respectively). OZ contraction was significantly higher in right compared with left eyes in group 1 (P = .05), but not in group 2 (P = .95). In tPRK, refractive outcomes, wasted tissue, and OZ contraction depend little on preexisting corneal epithelial thickness in corneas with normal range epithelial thickness. However, OZ contraction may be a concern in lower amount of ablations.

Objective Spherical Refractive Error Estimation Using Ocular Biometrics

Objective: To investigate the potential of clinical application spherical refractive error (SpRx) estimation using Ocular Biometrics (OB). Methods: 28 children aged from 6 to 14 years old with inter-ocular SpRx difference between 1 to 2 Dioptres (D) were recruited. Both eyes were measured with non-cycloplegia subjective refraction. OB was performed by the IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany). For OB SpRx estimation, right eye Intraocular Lens Power (IOL), (A constant 118) was taken with right eye SpRx, the flattest central corneal curvature (FK) and Axial Length (AL) using SRK/T formula. Left eye OB SpRx was taken using identical calculation with right eye IOL, left eye FK and AL respectively. Results: No statistically inter-ocular differences were observed of the average FK (p=0.84) and average lens thickness (p=0.88), but not average AL (p&lt;0.01). Average left eye SpRx by OB estimation and subjective refraction were determined as -2.86±1.02D and -2.82 ±1.16D (mean±SD) respectively. No significantly difference (p=0.84) and highly correlation (r=0.94. p&lt;0.01) were found. Conclusion: Objective SpRx appears to be reliably estimated using OB. It likely provides a crucial SpRx reference for comparison with subjective refraction. OB SpRx may also play a vital role for monitoring the children myopic progression.

Alteration in pattern reversal visual evoked potential in pediatric population with amblyopia and spherical refractive errors.

Purpose:To study the effect of refractive errors on pattern visual evoked potential (VEP) recordings in the pediatric population.Methods:This cross-sectional observational study assessed 240 eyes of 120 participants attending the outpatient department of a tertiary care center in North India. Participants were between 8 and 18 years of age; 30 participants each were recruited into four groups, namely emmetropia, myopia, hypermetropia, and amblyopia. They were then subjected to pattern reversal VEP, with P-100 amplitude and latency recorded for each participant.Results:The emmetropic group in this study provided normal values of P-100 parameters, namely P-100 latency and P-100 amplitude with readings of 115.78 ± 10.19 ms and 11.11 ± 4.08 mV, respectively. P-100 amplitude was significant compared to P-100 latency in detecting the presence or absence of a specific type of refractive error. It was found that there was a significant association between severity of myopia and P-100 latency (both unaided and aided) with P < 0.05. The severity of hypermetropia showed a significant association with P-100 amplitude (unaided) (P < 0.05). Receiver operating characteristics analysis revealed P-100 amplitude to be a good predictor of refractive error and the cut-offs were calculated.Conclusion:The P-100 parameters of the pediatric Indian population were comparatively higher than conventional values. P-100 latency seemed to better correlate with myopia, while hypermetropia correlated with P-100 amplitude. P-100 amplitude appears to be the most significant predictor of the presence of refractive error in an individual.

The underground explosion point high precision measurement method based on multidimensional information fusion of vibration sensors

PurposeThe purpose of this paper is to solve the problem that the location of the initiation point cannot be measured accurately in the shallow underground space, this paper proposes a method, which is based on fusion of multidimensional vibration sensor information, to locate single shallow underground sources.Design/methodology/approachFirst, in this paper, using the characteristics of low multipath interference and good P-wave polarization in the near field, the adaptive covariance matrix algorithm is used to extract the polarization angle information of the P-wave and the short term averaging/long term averaging algorithm is used to extract the first break travel time information. Second, a hybrid positioning model based on travel time and polarization angle is constructed. Third, the positioning model is taken as the particle update fitness function of quantum-behaved particle swarm optimization and calculation is performed in the hybrid positioning model. Finally, the experiment verification is carried out in the field.FindingsThe experimental results show that, with root mean square error, spherical error probable and fitness value as evaluation indicators, the positioning performance of this method is better than that without speed prediction. And the positioning accuracy of this method has been improved by nearly 30%, giving all of the three tests a positioning error within 0.5 m and a fitness less than 1.Originality/valueThis method provides a new idea for high-precision positioning of shallow underground single source. It has a certain engineering application value in the fields of directional demolition of engineering blasting, water inrush and burst mud prediction, fuze position measurement, underground initiation point positioning of ammunition, mine blasting monitoring and so on.

Next-Generation Sequencing Screening of 43 Families with Non-Syndromic Early-Onset High Myopia: A Clinical and Genetic Study.

Early-onset high myopia (EoHM) is a disease that causes a spherical refraction error of ≥−6 diopters before 10 years of age, with potential multiple ocular complications. In this article, we report a clinical and genetic study of 43 families with EoHM recruited in our center. A complete ophthalmological evaluation was performed, and a sample of peripheral blood was obtained from proband and family members. DNA was analyzed using a customized next-generation sequencing panel that included 419 genes related to ophthalmological disorders with a suspected genetic cause, and genes related to EoHM pathogenesis. We detected pathogenic and likely pathogenic variants in 23.9% of the families and detected variants of unknown significance in 76.1%. Of these, 5.7% were found in genes related to non-syndromic EoHM, 48.6% in genes associated with inherited retinal dystrophies that can include a syndromic phenotype, and 45.7% in genes that are not directly related to EoHM or retinal dystrophy. We found no candidate genes in 23% of the patients, which suggests that further studies are needed. We propose a systematic genetic analysis for patients with EoHM because it helps with follow-up, prognosis and genetic counseling.

Осевая длина глаза у пожилого населения Южного Урала (по данным исследования «Ural Very Old Study)

Intrоduction. Various biometric indicators of the eyeball in certain categories of the population continue to be the subject of research and discussion among specialists. At the same time, the information provided by different authors regarding the normal values of the length of the axial length of the eye is quite contradictory, while the norm indicators in certain population groups and subgroups are of great value. This fact was the reason for the present study. Material and methods. Between 2017 and 2020 The Ufa Eye Research Institute conducted a descriptive and analytical population study Ural Very Old Study (UVOS), in which 1526 participants took part. Results. The axial length of the eyeball in the population of the Republic of Bashkortostan (RB) aged 85 years and older is, on average, 23.11±1.08 mm. The conducted multivariate linear regression analysis showed the most statistically significant association of axial length (cumulative coefficient of determination R² =0.70) with factors such as height (p&lt;0.001), level of education (p=0.002), refractive power of the cornea (p&lt;0.001), spherical refractive error (p&lt;0.001). Conclusion. The morphometric and correlation features of the length of the anterior-posterior axis of the eyeball revealed in the UVOS study determine the presence of regional specificity of the anatomical and nosological characteristics of the organ of vision in the population of the Republic of Bashkortostan aged 85 and older. Key words: axial length, population study, year 85 and older

Corneal Cross-Linking in Pellucid Marginal Degeneration: Evaluation after Five Years.

Purpose:To evaluate the long-term outcome of corneal cross-linking (CXL) for pellucid marginal degeneration (PMD).Methods:In a retrospective study, forty eyes of forty patients were enrolled. All subjects had undergone CXL for PMD at least 5 years before the assessments. Visual acuity, refraction, and topography data were compared to their respective values before CXL.Results:The comparison between mean preoperative logMAR uncorrected visual acuity and 5-year postoperative evaluation revealed no significant change (1.20 ± 0.65 and 1.17 ± 0.64, P > 0.05). No statistically significant difference was noted comparing preoperative mean logMAR best-corrected visual acuity (BCVA) and postoperative mean logMAR BCVA (0.24 ± 0.19 and 0.22 ± 0.20, P > 0.05). We did not find any significant difference between pre- and postoperative spherical equivalent and spherical refractive errors (P = 0.419 and P = 0.396, respectively). Regarding the BCVA Snellen lines, 23 eyes had no significant change in pre- and postoperative examinations, 11 eyes had improvement, and 6 subjects showed worsening defined as significant when two or more lines change. The spherical equivalent refractive error improved in 4 subjects, was stable in 25, and worsened in 11 subjects, while a 0.5 diopter or more myopic change was considered significant. Furthermore, regarding steep keratometry values, 25 subjects were stable, 7 had improvements, and 8 worsened.Conclusion:CXL appears to be a safe and effective procedure to halt the progression of PMD.

Structural, Microvascular, and Functional Findings Associated with Fovea Plana.

To analyse structural (OCT), microvascular (OCTA), and functional changes (BCVA, mfERG) associated with fovea plana and to compare it to healthy controls. A retrospective observational study was performed on 13 patients (26 eyes; aged 34.46 y ± 20.26) with a clinical picture of fovea plana and 15 controls (30 eyes; aged: 41.47 y ± 14.03). In fovea plana, BCVA ranged from 0.25 to 1.0, with a spherical error of - 5.5 to + 18.0 dpt. Posterior segment changes included elevated papillomacular retinal fold, uveal effusion syndrome, crowded optic discs, and hypopigmented fundus. OCTA imaging of the superficial (FAZ-S), intermediate (FAZ-I), and deep foveal avascular zone (FAZ-D) confirmed absence of foveal avascular zone (FAZ-S in 13 eyes, FAZ-I in 21eyes, and FAZ-D in 10 eyes). Fovea plana patients had a significantly smaller FAZ-S, FAZ-I, and FAZ-D than controls (p < 0.001). Within the fovea plana group, a smaller FAZ-S correlated with reduced BCVA (p = 0.004) and with reduced mfERGs in zones 1 and 2 (p = 0.001 and p = 0.017). Also, a smaller FAZ-D showed positive correlations with the mfERG, with statistically significant values in zones 1 and 2 (p = 0.003 and p = 0.017). In conclusion, our results confirm an altered structural, microvascular, and functional pattern in patients with a clinical picture of fovea plana. As documented by the functional microvascular interactions in our study, the developmental arrest in foveation reflects the functional maturation by means of visual acuity and central retinal function.

Studying the changes of corneal endothelium cells in patients with spherical refractive errors

Objective: To study of the relationship between spherical refractive errors and the changes in corneal endothelial cells. Methods: This sectional study, 1098 eyes of 663 persons attending the ophthalmological clinic at Tishreen University Hospital were studied between the years 2020-2021, they were divided into three groups according to the spherical equivalent value (193 nearsighted, 254 partially sighted, 216 long sighted), and also each was divided into three groups according to the value of the spherical equivalent. From the farsightedness and myopia groups to groups according to the severity of the refraction present (mild, moderate, severe), all participants underwent a complete ophthalmological examination including corneal endothelial cell counts by Endothelium Mic. Non contact, Specular Microscope, where the average of three successive measurements of endothelial cell density (MCD), coefficient of variation (CV) for cell volume, and hexogram (EX%) were taken. Results: The values of endothelial cell density (MCD) (P ˂ 0.05) and hexameric cell percentage (EX%) (P ˂ 0.05) decreased statistically significantly, while the value of the covariance (CV) increased (P ˂ 0.05) with increasing myopia, This change was at the expense of moderate myopia and severe myopia, while mild myopia did not have a statistically significant effect, as well as for hyperopia, where we did not find significant statistical differences in the three variables (MCD) (EX%) (CV) (P ˃ 0.05). Conclusion: Hyperopia does not affect the endothelial cells of the cornea, while moderate to severe myopia causes a significant change in the endothelial cells of the cornea.

Hemidivisional vector planning to reduce and regularize irregular astigmatism by laser treatment

PurposeTo demonstrate how hemidivisional vector planning of refractive laser treatments of astigmatism can be used to directly address idiopathic corneal irregular astigmatism that has an asymmetrical, non-orthogonal bow tie topography appearance.DesignCase study.MethodsThe cornea is conceptually divided into two hemidivisions along the flat meridian of the corneal topographic astigmatism (CorT), which means that each hemidivision will approximately correspond to one lobe of the asymmetric, non-orthogonal topographic bow tie. An astigmatism reduction treatment can then be planned separately for each hemidivision using the vector planning technique, based on both its two hemidivisional CorT measures and common manifest refractive cylinder. The remaining irregularity is then regularized, and the junctional zone smoothed across the flat meridian. The final intended treatment thus combines hemidivisional astigmatism reduction and regularization of the corneal astigmatism and spherical refractive error in one treatment application. This could be applied to LASIK, PRK, SMILE, and Transepithelial PRK procedures using Designer Cornea® software.ResultsA theoretical treatment profile is derived from an actual example of a cornea with idiopathic asymmetric non-orthogonal astigmatism. The three steps of the derivation are as follows: (i) astigmatism reduction through the use of the vector planning technique; (ii) regularization, and (iii) smoothing across the hemidivisional midline.ConclusionsHemidivisional vector planning treatments could potentially both reduce and regularize asymmetric non-orthogonal astigmatism. These treatments can be systematically customized to account for qualitative and quantitative differences between the two corneal hemidivisions at the same time as correction of coexistent myopia or hyperopia.

Uncorrected refractive error in a university community.

To determine the prevalence and pattern of uncorrected refractive error among staff of a Nigerian university. A cross-sectional study of consecutive staff of the University of Nigeria, Nsukka, Nigeria who presented for a 10-day free eye screening program. Demographic data and data on eye care awareness and knowledge were obtained with a combination of self-administered and interviewer-administered questionnaires in the English language. Clinical examinations included visual acuity taken at 6 m with Snellen's chart; noncontact tonometry; pen-torch eye examination; and direct ophthalmoscopy; autorefraction and subjective refraction. One thousand and eighty-three subjects aged 18-82 years (mean = 44.1 ± 12.15 years) comprising 568 females (52.4%) and 515 males (47.6%) were screened. Eighty-nine subjects (8.3%) were visually impaired and five subjects (0.5%) were blind. Three hundred and fifty-six subjects were diagnosed with refractive error (356/1083; 32.9%), out of which 149 subjects (41.9%) were uncorrected. The prevalence of uncorrected refractive error in this study population was 13.8%. Astigmatism was the commonest refractive error, whereas hypermetropia and hypermetropic astigmatism were the commonest spherical and astigmatic errors, respectively. A significant proportion of the staff of this Nigerian university still lives with uncorrected refractive error with its attendant consequences. Regular eye checks should be done by the staff of our universities and effort should be intensified in eye care awareness creation among the populace, including the apparently enlightened communities.

Preliminary Evaluation of a Smartphone App for Refractive Error Measurement.

PurposeThe purpose of this study was to evaluate the potential feasibility of using a smartphone app in myopia screening.MethodsThe app estimates myopic refractive error by measuring the far point distance for reading three 20/20 Tumbling E letters. In total, 113 myopic subjects with astigmatism no greater than −1.75 diopters (D) were enrolled from 5 sites. The mean age was 22 ± 8.5 years. The app measurement was compared with noncycloplegic subjective refraction measurement or autorefractor if subjective refraction was not available. In addition, 22 subjects were tested with the app for repeatability.ResultsFor 201 eyes included, the range of spherical equivalent refraction error was 0 to −10.2 D. The app measurement and clinical measurement was highly correlated (Pearson R = 0.91, P < 0.001). There was a small bias (0.17 D) in the app measurement overall, and it was significantly different across the 5 sites due to different age of subjects enrolled at those sites (P = 0.001) – young adults in their 20s were underestimated the most by 0.49 D, whereas children were overestimated by 0.29 D. The mean absolute deviation of the app measurement was 0.65 D. The repeatability of multiple testing in terms of 95% limit of agreement was ±0.61 D.ConclusionsOverall, the app measurement is consistent with clinical measurement performed by vision care professionals. The repeatability is comparable with that of some autorefractors. Age-associated human factors may influence the app measurement.Translational RelevanceThe app could be potentially used as a mass screening tool for myopia.

Accuracy of Toric Intraocular Lens Axis Alignment Using Manual Slit Lamp Method and CALLISTO Eye Image-Guided System

Aims: Image-guided systems are the gold standard for determining toric intraocular lens (IOL) axis alignment. However, their high cost prevents widespread use of these systems. As an alternative, a simpler and affordable method could be performed manually using a slit-lamp biomicroscope. This study aims to compare the accuracy of manual toric IOL axis marking using a slit-lamp compared to the CALLISTO eye image-guided system.&#x0D; Study Design: Prospective comparative&#x0D; Methods: In this prospective study, toric IOL axis alignment of 42 eyes with cataract and coexisting corneal astigmatism were evaluated using manual slitlamp method and CALLISTO eye image-guided method. Preoperative and postoperative uncorrected visual acuity, best corrected visual acuity, amount of spherical and astigmatic refractive errors, and postoperative IOL axis alignment were evaluated. Intraclass correlation of the manual method was calculated and the difference of IOL axis alignment to the image-guided method was compared.&#x0D; Results: Toric IOL implantation reduced the amount of astigmatic refractive error from -1.63 ± 0.65 D to -0.50 ± 0.19 D in the image-guided group and from -1.93 ± -0.90 D to -0.87 ± 0.26 D in the manual slitlamp group. As many as 90.5% of eyes in the image-guided group and 81.0% of eyes in the manual slitlamp group reached the target induced astigmatism (p=0.38). Manual axis marking showed intraclass correlation of 99.3%. However, when the manual method was compared to the image-guided method a mean difference in axis alignment of 10.98o (95% confidence interval: 9.32o - 12.63o) was observed.&#x0D; Conclusions: Alignment of toric IOL axis using the manual method demonstrated a consistent result; yet producing a considerable difference to the result of the image-guided method.

An onboard-eye-to-hand visual servo and task coordination control for aerial manipulator based on a spherical model

Compared with the unmanned aerial vehicle (UAV), the aerial manipulator extends the ability to interact with the environment by using the onboard manipulator. The complex dynamic characteristics of the combined system increase the challenges of accurately control the aerial manipulator to approximate the target object. In this paper, an onboard-eye-to-hand visual servo and task coordination control strategy is proposed for the aerial manipulator to enhance the accurate manipulation and flight stability. By establishing a new spherical coordinate error equation, the flying platform (quadrotor) and onboard manipulator can be controlled simultaneously. Meanwhile, the multi-task coordinated control scheme is adopted to achieve precise positioning and grasping of the target object, including estimating the object pose, dynamically compensating the change of the center of gravity of the aerial manipulator, and avoiding the onboard manipulator joint limitations. The stability of the closed-loop system is analyzed by the Lyapunov method. Finally, the feasibility of the proposed visual servo method is verified in simulations and real-world outdoor experiments, respectively. The strengths of the proposed method are demonstrated by comparing it with the conventional visual servo method.

Characteristics and variability of iridocorneal angle: an anterior segment optical coherence tomography study

AbstractPurposeWe aimed to assess the iridocorneal angle by Anterior Segment Optical Coherence Tomography (AS‐OCT) and to identify relations between angle measurements and subject factors in a healthy Caucasian Tunisian population.MethodsA prospective cross‐sectional study was performed in 201 right eyes of 201 healthy subjects.All patients underwent a complete ophthalmic examination, automated refraction, ultrasound biometry and AS‐OCT examination at the same day. The iridocorneal angle measurements including trabecular iris angle (TIA), angle opening distance 500 (AOD500) and trabecular iris space area 500 (TISA500) were manually measured using AS‐OCT. Correlations and associations were examined between angle measurements and demographic, clinical and ocular factors.ResultsThe means recorded were TIA = 34.6 ± 11.4 degrees, AOD500 = 515 ± 260.7 µm and TISA = 500 0.178 ± 0.091 mm². We found that 90.3% of the iridocorneal angles were open.Correlations were detected between angle means and age (R = −0.414; p &lt; 0.01), intraocular pressure (R = −0.145; p &lt; 0.01), spherical error (R = −0.410; p &lt; 0.01), anterior chamber depth (R = 0.734; p &lt; 0.01), axial length (R = 0.489; p &lt; 0.01) and lens thickness (R = −0.519; p &lt; 0.01).No relation was observed with sex (p = 0.084).ConclusionsAS‐OCT is a non‐invasive tool to identify subjects at risk of angle closure. In this Caucasian population, 90.3 % of the iridocorneal angles were open. AOD 500 and TISA 500 were as reliable as TIA in iridocorneal angle assessment. The angle width was correlated with demographic and ocular factors. Among the main limitations, was the fact that we did not measure the lens vault despite the known contribution of this factor to angle width variation.

Post-operative outcomes of small-incision lenticule extraction in patients with moderate to high astigmatism.

Purpose:To evaluate the visual outcomes of patients who underwent small-incision lenticule extraction (SMILE) for the treatment of myopic astigmatism with high cylinders (>2.5 diopters, D).Methods:Forty-two eyes of myopic astigmatism with a spherical error of magnitude between − 0.5 and − 6.0 Ds, cylindrical error of − 2.5 to − 4.5 Dcyl were included in the retrospective study. All patients were tested preoperatively and on days 1, 10, and 30 for uncorrected distance visual acuity, manifest refraction, and corrected distance visual acuity. Additional preoperative assessments were done including measurement of corneal thickness, corneal topography, and examination for ocular surface disease. All procedures were performed by a single experienced surgeon. VisuMax laser system (Carl Zeiss Meditec AG, Jena, Germany) was utilized for all the corrective refractive procedures.Results:Forty-two eyes were included. The logarithm of the minimum angle of resolution Uncorrected distance visual acuity (UDVA) was 1 ± 0.25 preoperatively and 0.00 ± 0.00 on postoperative day 30. There was no loss of corrected distance visual acuity (CDVA) lines.Conclusion:SMILE is a successful procedure in the treatment of both myopic spherical and cylindrical refractive errors including high cylindrical errors >-3 to − 4.5 Dcyl.

Perfecting Laser Treatment for Regular and Irregular Astigmatism

Perfecting the treatment of regular and irregular astigmatism using laser-assisted in situ keratomileusis, photorefractive keratectomy, and small in situ lenticule extraction is possible by reducing and regularizing the asymmetric, non-orthogonal corneal shape while correcting spherical refractive error. Such perfecting treatment may be achieved by conceptually dividing the cornea into two hemidivisions and applying vector planning to optimally customize each half of the cornea to the minimum regular astigmatism possible. This innovative treatment could improve best-corrected visual acuity and minimize aberrations.

18-month results of double-fanged 5-0 polypropylene suture transscleral bag fixation in subluxated cataracts.

To evaluate the stability and efficacy of the double-flanged 5-0 polypropylene suture to fixate subluxated cataracts at 18 months and the possible complications of this new technique. This technique uses a 5-0 polypropylene monofilament to create two flanges with a thermocautery, for fixation of a capsular tension segment to the sclera to fix the subluxated capsular bag. This technique was implemented in 17 eyes requiring intraocular lens implantation in a setting of zonular dialysis due to trauma, Marfan syndrome, microspherophakia, idiopathic disease, and post-phacoemulsification status. Follow-up of the patients occurred at 18 months. Best-corrected visual acuity improved significantly from 0.85 to 0.39 (logMAR), whereas the spherical and cylindrical refractive errors and intraocular pressure remained stable from preoperation. No suture photodegradation or pseudophacodonesis were detected. The double-flanged 5-0 polypropylene suture transscleral bag fixation technique has shown favorable long-term outcomes in terms of bag intraocular lens/complex fixation and stability. In eyes with zonular weakness or dialysis, this technique appears to be a safe and knotless option for cataract surgery.