Steeper Corneal Curvature Research Articles

Topographic and Surgical Risk Factors for Early Myopic Regression between Small Incision Lenticule Extraction and Laser In Situ Keratomileusis.

Our objective was to evaluate the topographic and surgical factors of early myopic regression between laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE). A retrospective case-control study was conducted, and 368 and 92 eyes were enrolled in the LASIK and SMILE groups via propensity score matching (PSM). Visual acuity, refractive status, axial length, and topographic/surgical parameters were collected. Multiple linear regression was applied to the yield coefficient and the 95% confidence interval (CI) of the parameters. The cumulative incidence of early myopic regression was higher in the LASIK group (p < 0.001). In the SMILE group, a lower central corneal thickness (CCT) thinnest value and a higher corneal cylinder associated with early myopic regression were observed; meanwhile, in the LASIK group, a lower CCT thinnest value, a higher steep corneal curvature, a larger optic zone, and a lower flap thickness related to early myopic regression were observed (all p < 0.05). In the SMILE group, a higher CCT difference correlated with early myopic regression was observed compared to the LASIK group (p = 0.030), and higher steep corneal curvature and lower cap/flap thickness (both p < 0.05) correlated with early myopic regression were observed in the LASIK group compared to the SMILE group. In conclusion, CCT differences significantly influence early myopic regression in the SMILE group; meanwhile, corneal curvature and flap thickness affect early myopic regression principally in the LASIK group.

Topographic and surgical risk factors for high postoperative residual astigmatism after small incision lenticule extraction in patients with different degrees of myopia: a retrospective cohort study

BackgroundTo evaluate the possible topographic and surgical risk factors for high postoperative residual astigmatism in patients who undergo small-incision lenticule extraction (SMILE) surgery and have different myopia degrees.MethodsA retrospective cohort study was conducted, and patients who underwent SMILE surgery were enrolled. A total of 80 and 150 eyes from 40 to 75 individuals, respectively, were selected as the low myopia and high myopia groups. The demographic data, visual acuity, refraction, topographic parameters and surgical settings were recorded. Multiple linear regression with interaction tests were performed to survey the risk factors for high postoperative residual astigmatism in each group.ResultsFive (6.25%) and 9 (6.00%) eyes presented with high postoperative residual astigmatism in the low myopia and high myopia groups, respectively, but these differences were not significant (P = 0.569). A steep corneal curvature was correlated with a greater risk of high postoperative residual astigmatism in the low myopia group (P = 0.015), while a higher degree of cycloplegic cylinder power, steeper corneal curvature, greater topographic cylinder power, smaller optic zone and longer incision length were associated with a high rate of postoperative residual astigmatism in the high myopia group (all P < 0.05). In addition, the interaction effects of cycloplegic and topographic cylinder power and longer incision length on the incidence of high postoperative residual astigmatism development were more evident in the high myopia group than in the low myopia group (all P < 0.05).ConclusionsA steep corneal curvature correlates with a high risk of high postoperative residual astigmatism after SMILE surgery, and a higher degree of cycloplegic and topographic cylinder and longer incision are associated with high postoperative residual astigmatism in individuals with high myopia.

Possible risk factors of opaque bubble layer and its effect on high-order aberrations after small incision Lenticule extraction.

To evaluate the possible risk factors of opaque bubble layer (OBL) formation in small incision lenticule extraction (SMILE) surgery and its effects on visual quality. Fifty-six eyes from 28 patients were included in this study. The preoperative parameters and intraoperative designs were recorded. Corneal high-order aberrations (HOAs), point spread function (PSF), and modulation transfer function (MTF) were measured using iTrace at pre-operation, 1 week, 1 month, and 3 months after SMILE. Generalized Estimating Equation and Linear Mixed Effects Model were employed for statistical analysis. The mean OBL area in SMILE surgery was 2.75% ± 1.25%. The patients were divided into groups based on whether the OBL was greater than the mean group or less than the mean group. Compared to the group with a smaller OBL area, the group with the larger OBL area had steeper corneal curvature and thinner cap thickness, the OBL area was positively correlated with the preoperative keratometry (r = 0.21, p = 0.04) and preoperative spherical value (r = 0.47, p = 0.01). The group with the larger OBL area induced more corneal SA and trefoil at 1 week postoperatively, but the difference was not significant at 1 month and 3 months postoperatively. A steep corneal curvature, thin cap thickness, and high preoperative spherical value are possible risk factors for OBL formation in SMILE surgery. The OBL increased the ocular and corneal HOAs postoperatively for a short period (1 week), while it did not affect the long-term outcomes.

Evaluation of Ciliary Body Morphology and Position of Implantable Collamer Lens in Low-Vault Eyes Using Ultrasound Biomicroscopy.

To investigate the ciliary body anatomy and position of the implantable collamer lens (ICL) in low-vault eyes and analyze factors related to insufficient vault. Zhongshan Ophthalmic Center, Guangzhou, China. Retrospective case-control observational study. In this study, 73 eyes of 73 patients with insufficient vault (＜250 µm) were matched with 73 eyes with an ideal vault (250 to 750 µm). Ultrasound biomicroscopy (UBM) was used to determine the ciliary body morphology and ICL position. The biometric parameters acquired by Scheimpflug tomography were compared. The correlation between the vault and these factors was analyzed, and the Least Absolute Shrinkage and Selection Operator (LASSO) method was used to screen the risk factors for low-vault. The low-vault group had a steeper corneal curvature, thicker lens thickness (LT), higher crystalline lens rise, and shorter axial length (AL) (All P <.005). The ciliary process length (CPL) and maximum ciliary body thickness (CBTmax) were significantly smaller, and the trabecular-ciliary angle (TCA), iris-ciliary angle (ICA), and ciliary sulus width (CSW) were significantly greater in the low-vault eyes. (All P <.005). The low-vault group had more ICL haptics below the ciliary process, and TCA, ICA, CPL, CBTmax, CSW, and haptic position were related to the postoperative vault (All P <.05). CPL, AL, and LT were identified as predictors of a low-vault. Malposition of ICL haptics behind the ciliary process is a risk factor for low-vault. A shorter CPL, thicker LT, and shorter AL are significant risk factors for postoperative low-vault.

Deep learning prediction of steep and flat corneal curvature using fundus photography in post-COVID telemedicine era.

Recently, fundus photography (FP) is being increasingly used. Corneal curvature is an essential factor in refractive errors and is associated with several pathological corneal conditions. As FP-based examination systems have already been widely distributed, it would be helpful for telemedicine to extract information such as corneal curvature using FP. This study aims to develop a deep learning model based on FP for corneal curvature prediction by categorizing corneas into steep, regular, and flat groups. The EfficientNetB0 architecture with transfer learning was used to learn FP patterns to predict flat, regular, and steep corneas. In validation, the model achieved a multiclass accuracy of 0.727, a Matthews correlation coefficient of 0.519, and an unweighted Cohen's κ of 0.590. The areas under the receiver operating characteristic curves for binary prediction of flat and steep corneas were 0.863 and 0.848, respectively. The optic nerve and its peripheral areas were the main focus of the model. The developed algorithm shows that FP can potentially be used as an imaging modality to estimate corneal curvature in the post-COVID-19 era, whereby patients may benefit from the detection of abnormal corneal curvatures using FP in the telemedicine setting.

Influence of Anterior Segment Swept-source Optical Coherence Tomographic Profiles in the Temporal Decentration of Orthokeratology Treatment Zone

Purpose: This study aims to elucidate the factors contributing to the temporal decentration of the orthokeratology lens (OK lens) treatment zone, employing profiles obtained from anterior segment swept-source optical coherence tomography (AS SS-OCT).Methods: The measurements prior to treatment were taken using AS SS-OCT (Anterion; Heidelberg, Germany) in subjects who had worn OK lenses for at least 2 weeks. The collected data encompassed anterior corneal refractive profiles, corneal thickness profiles, anterior corneal elevation profiles, and anterior corneal aberrations. A comparison was drawn between two groups: the temporal decentration (TD) group and the control (no decentration [ND]) group, based on the presence of temporal decentration of the treatment zone.Results: The analysis included a total of 63 eyes (48 eyes in the ND group and 15 eyes in the TD group) from 33 patients (10.6 ± 2.2 y). No significant differences were observed in axial length, spherical equivalent, and horizontal corneal diameter between groups. However, the TD group exhibited higher values in terms of anterior SimK&lt;sub&gt;mean&lt;/sub&gt; (D), central K (D), and anterior K at temporal and nasal 3.0, 2.0, and 1.0 mm points. Moreover, the TD group displayed a higher horizontal meridian to vertical meridian ratio (H/V K ratio at 4.0 mm diameter) of anterior corneal K at 4.0 mm diameter ring. The ND group showed a higher vertical distance to the maximum corneal power (K&lt;sub&gt;max&lt;/sub&gt; y) compared to the TD group. Although high order root mean square aberrations were relatively higher in the ND group, statistical significance was marginally attained (&lt;i&gt;p&lt;/i&gt; = 0.047).Conclusions: The temporal decentration of the OK lens treatment zone was determined to be linked with steeper corneal curvature at the central and horizontal meridians, an augmented relative steepness of the horizontal meridian at the 4.0 mm diameter, and a vertical displacement in K&lt;sub&gt;max&lt;/sub&gt; on AS SS-OCT.

Investigation of ocular biometry in 4– to 9-year-old Chinese children

PurposeTo investigate the distribution and changes in ocular biometry in 4-to to 9-year-old Chinese children and to compare the differences between age and genders in these parameters.MethodsThis was a school-based cross-sectional study. A total of 1,528 Chinese children, aged 4–9 years, from one primary school and 12 kindergartens, were included in the study. Axial length, corneal curvature, anterior chamber depth, and corneal diameter were measured for each child.ResultsAL and anterior chamber depth gradually increased with age in both genders. No significant changes in corneal curvature or corneal diameter were detected at different ages in either genders group. The mean ALs of males and females were 22.94 ± 0.80 mm and 22.38 ± 0.79 mm, respectively. The mean corneal curvatures of males and females were 43.05 ± 1.37 D and 43.75 ± 1.48 D, respectively. The mean anterior chamber depth of males and females were 3.47 ± 0.24 mm and 3.38 ± 0.25 mm, respectively. The mean corneal diameter of males and females were 12.08 ± 0.43 mm and 11.94 ± 0.44 mm, respectively. Females had consistently shorter ALs, shorter anterior chamber depth, smaller corneal diameter, and steeper corneal curvatures than males at any age.ConclusionsBoys had larger dimensions than girls for all ocular parameters except corneal curvature (flatter). Boys and girls showed similar trends for all parameters. Axial length and anterior chamber depth increased from 4 to 9 years of age, whereas corneal diameter and curvature did not change with age in either genders.

Ocular geometry in adults born small, appropriate or large for gestational age at term.

Intrauterine growth restriction leading to a birth weight (BW) which is too low for gestational age (GA) is a known risk factor for various altered organ morphologies and dysfunction in later life. This study aimed to determine for the first time the effects of being small (SGA) or large for gestational age (LGA) on the ocular geometry of adults born at term. All participants were examined with optical biometry (LenStar 900, Haag Streit) to compare the corneal curvature, white-to-white distance, anterior chamber depth, lens thickness and axial length between former moderate (BW percentile 3rd to <10th) and severe (BW <3rd percentile) SGA, controls (BW 10th-90th percentile) and former moderate (BW >90th to 97th percentile) and severe (BW >97th percentile) LGA. Multivariable linear regression was used to analyse associations with GA, BW percentile categories, placental insufficiency, preeclampsia and breastfeeding after adjustment for age and sex. In total, 589 eyes of 296 individuals born at term (aged 30.0 ± 9.4 years, 156 females) were examined, including 40 severe SGA, 38 moderate SGA, 140 with normal BW, 38 moderate LGA and 40 severe LGA. There was an association between a steeper corneal curvature with moderate (B = -0.201; p < 0.001) and severe SGA (B = -0.199; p < 0.001), with extreme SGA associated with smaller white-to-white (B = -0.263; p = 0.001) and a shorter axial length (B = -0.524; p = 0.031). Severe and moderate prenatal growth restriction in adults born at term leads to an altered ocular geometry, namely a steepening of the cornea and a smaller corneal diameter.

Comparable postoperative myopic shift in eyes with retinal vascular diseases and vitreomacular interface diseases after phacovitrectomy.

To compare the predictive refractive error (PRE) of intraocular lens (IOL) power between retinal vascular and vitreomacular interface diseases after phacovitrectomy. We retrospectively reviewed patients who underwent phacovitrectomy for various retinal diseases. Patients with retinal vascular diseases and vitreomacular interface diseases were included in group A and group B, respectively. Age- and gender-matched senile cataract patients with phacoemulsification were set as controls. The mean PRE and absolute value of refractive error (ARE) among different groups were compared. The associated risk factors with ARE were also analyzed in the univariate and multivariate analyses. In total, 106 patients (Group A), 108 patients (Group B), and 110 patients as controls were included. The PRE in Group A (- 0.35 ± 0.83D) and Group B (- 0.53 ± 0.74D) were more myopic compared to the control group (- 0.11 ± 0.58D) (p < 0.05). The ARE in Group A (0.70 ± 0.57D) and Group B (0.75 ± 0.51D) were significantly higher compared to the control group (0.47 ± 0.35D) (p < 0.05). There were no significant differences in the PRE and ARE values between the two study groups (p = 0.267 and 0.861, respectively). There were no significant differences of the PRE and ARE in the eyes with silicone oil tamponade (- 0.63 ± 0.75D, 0.81 ± 0.54D) and gas tamponade (- 0.42 ± 0.83D, 0.74 ± 0.56D) (p = 0.693 and 0.988, respectively). In the multivariate model, preoperative LogMAR visual acuity (β = 0.162, 95%CI = 0.113-0.211, p < 0.001), mean corneal curvature (β = 0.105, 95% CI = 0.074-0.135, p < 0.001), and age (β = 0.012, 95% CI = 0.005-0.019, p = 0.001) were all positively correlated with the ARE. Postoperative myopic shift after phacovitrectomy may be comparable in retinal vascular diseases and vitreomacular interface diseases, no matter the gas or silicone oil tamponade. Older age, steeper corneal curvature, and worse preoperative visual acuity could produce more prediction errors.

Association of Corneal Biomechanics Properties with Myopia in a Child and a Parent Cohort: Hong Kong Children Eye Study

Associations between corneal biomechanics, axial elongation and myopia are important but previous results are conflicting. Our population-based study aimed to investigate factors associated with corneal biomechanics, and their relationships with myopia in children and adults. Data from 3643 children and 1994 parents showed that children had smaller deformation amplitudes (DA) than parents (p < 0.001). A larger DA was significantly associated with elongated axial length (AL; children: ß = 0.011; adults: ß = 0.0013), higher corneal curvature (children: ß = 0.0086; adults: ß = 0.0096), older age (children: ß = 0.010; adults: ß = 0.0013), and lower intraocular pressure (IOP; children: ß = −0.029; adults: ß = −0.031) in both cohorts. The coefficient of age for DA in children was larger than in adults (p < 0.001), indicating that the DA change with age in children is faster than in adults. DA was significantly associated with spherical equivalent (p < 0.001) resulting from its correlation with AL and corneal curvature. In conclusion, the cornea is more deformable in adults than in children, whereas corneal deformation amplitude increases faster with age in children than that in adults, along with AL elongation. Longer AL, steeper corneal curvature, older age and smaller IOP correspond to a more deformable cornea. The association between corneal deformation amplitude and refraction was mediated via AL and corneal curvature.

Influence of corneal shape parameters on corneal deformation responses measured with a Scheimpflug camera.

To investigate the effect of corneal shape parameters on corneal deformation responses measured with a Scheimpflug camera. A total of 241 eyes of 241 participants were enrolled in this study. The anterior and posterior corneal curvature radii (CCR), anterior and posterior corneal Q-values, and corneal diameters of the participants were measured using the Pentacam HR. A total of 17 corneal deformation parameters including time, velocity, deflection amplitude, length, and area during ingoing applanation, highest concavity, and outgoing applanation were recorded by corneal visualization using Scheimpflug technology (Corvis ST). The effect of corneal shape parameters on corneal deformation responses was evaluated using multivariate regression models. Multivariate regression analyses showed that six, five, four, and three corneal deformation parameters were significantly correlated with anterior CCR, posterior CCR, anterior Q-value, and posterior Q-value, respectively. Steeper anterior corneal curvature was associated with faster velocity during ingoing applanation and greater deformation during outgoing applanation. Steeper posterior corneal curvature was correlated with faster velocity during outgoing applanation and greater deformation during ingoing applanation. Eyes that had steeper corneal curvatures were associated with less stiff corneas. More negative anterior Q-value corresponded with faster velocity and greater deformation during ingoing applanation. Eyes that had more prolate posterior corneal surfaces showed more resistance to corneal deformation at the highest concavity. However, corneal diameter was not selected in any corneal deformation parameters models. Corneal deformation response is significantly influenced by anterior and posterior corneal curvature and corneal asphericity, but not corneal diameter.

Influence of upper blepharoplasty on intraocular lens calculation.

To determine the effect of upper blepharoplasty on corneal topography and intraocular lens power calculation using Galilei and IOLMaster. Thirty patients submitted to upper blepharoplasty from May 2014 to March 2017 at the Hospital Oftalmológico de Sorocaba (São Paulo, Brazil) were included in this observational case series. All patients underwent imaging sessions with Galilei and IOLMaster preoperatively (baseline) and at 1 and 6 months postoperatively. Primary outcome measures using both devices included flattest, average, and steepest corneal curvature, corneal astigmatism, and blepharoplasty-induced corneal astigmatism. Determination of axial length and lens power calculation were performed using only IOLMaster (Holladay formula). Paired t-test and vectorial analysis were used for statistical analysis. Sixty eyes from 30 patients were prospectively included. Vectorial analysis showed that 6 months after surgery, blepharoplasty induced on average 0.39 D and 0.31 D of corneal astigmatism, as measured with Galilei and IOLMaster, respectively. IOLMaster measurements showed that average corneal curvature (44.56 vs 44.64 D, p=0.01), steepest corneal curvature (45.17 vs 45.31, p=0.01) and corneal astigmatism (1.22 vs 1.34, p=0.03) were higher 6 months after surgery. IOLMaster measurements also showed that intraocular lens power was significantly smaller 6 months after surgery (22.07 vs 21.93, p=0.004). All other parameters showed no change for comparisons between baseline and 6 months (p>0.05 for all comparisons). Upper eyelid blepharoplasty influenced intraocular lens calculation using the IOLMaster. However, the influence was not clinically significant. No topographic changes were found using Galilei.

Optimization of intraocular lens power calculation in pseudoexfoliation syndrome

To assess the impact of pseudoexfoliation syndrome (PEX) on the accuracy of intraocular lens (IOL) power calculation. The study included 243 patients who underwent phacoemulsification (PE); they were divided into the control (no PEX signs, n=131) and study (signs of PEX, n=112) groups. Barrett Universal II formula was used for IOL calculation by optical biometry (IOL-Master 500). Obtained refraction (autorefractometer Topcon-8800) was compared with target refraction to assess IOL calculation accuracy 1 month after PE. Patients with PEX had significantly shallower anterior chamber compared to the control group (2.86±0.43 versus 3.0±0.43 mm, p=0.003) and steeper corneal curvature (44.31±1.5 versus 43.7±2.59 D, p=0.052). There was significant difference in absolute error of IOL calculation between the groups (-0.02±0.45 versus 0.17±0.55 D for control and study groups, respectively, p=0.004). There was no difference in IOL calculation error depending on the implanted IOL models (AcrySof SA60AT and Akreos Adapt AO) in the control group. However, implantation of SA60AT in the study group showed significant difference in IOL calculation error compared with Akreos (0.3±0.57 versus 0.04±0.51 D, p=0.01). Using linear regression, optimized A-constants were suggested for these types of IOLs for patients with PEX (118.83 for SA60AT and 118.44 for Akreos).

Prognostic Factors for Axial Length Elongation and Posterior Staphyloma in Adults With High Myopia: A Japanese Observational Study

To identify prognostic factors for axial length (AL) elongation and incidence of posterior staphyloma (PS) in adult Japanese patients with high myopia. Retrospective, observational cohort study. Six-year follow-up data for 345 patients (620 eyes with AL ≥ 26.5mm and spherical equivalent [SE] ≤- 8.00 diopters) admitted to the Tokyo Medical and Dental University Hospital from 2007 to 2017 were analyzed retrospectively. Main outcome measures were change in AL from baseline, factors associated with AL, categorization of eyes with high myopia, factors associated with incidence of PS, and impact of PS on myopic maculopathy and visual function. The mean annual increase in AL was 0.03mm. Presence of optic nerve disc conus (P= .025), steeper corneal curvature, lower SE, and decreased choroidal thickness (CT) (all P < .001) were associated with increased AL in univariate and multivariate analyses. Younger age (P= .003) and no use of intraocular pressure-lowering medications (P= .046) were associated with increased AL. Eyes with high myopia were categorized using factor analysis as associated with glaucoma, severe pathologic myopia, and mild-to-moderate pathologic myopia. Older age, increased AL, glaucoma, and choroidal thinning (all P ≤ .001) were identified as significant risk factors for the incidence of PS in univariate and/or multivariate analyses. Incidence of PS was a precursor for myopic maculopathy and visual field defects. Optic nerve disc conus, steeper corneal curvature, lower SE, decreased CT, and no use of intraocular pressure-lowering medications were prognostic factors for increased AL. Older age, increased AL, glaucoma, and decreased CT were prognostic factors for PS.

Accuracy of intraocular lens calculation formulas in cataract patients with steep corneal curvature.

ObjectiveTo compare the accuracy of five kinds of intraocular lens calculation formulas (SRK/T, Haigis, Hoffer Q, Holladay and Barrett Universal Ⅱ) in cataract patients with steep curvature cornea ≥ 46.0 diopters.MethodsThis is a retrospective study of cataract phacoemulsification combined with intraocular lens implantation in patients with steep curvature cornea (corneal curvature ≥ 46D). The refractive prediction errors of IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) using User Group for Laser Interference Biometry (ULIB) constants were evaluated and compared. Objective refraction results were assessed at one month postoperatively. According to axial length (AL), all patients were divided into three groups: short AL group (<22mm), normal AL group (>22 to ≤24.5mm) and long AL group (>24.5mm). Calculate the refractive error and absolute refractive error (AE) between the actual postoperative refractive power and the predicted postoperative refractive power. The covariance analysis was used for the comparison of five formulas in each group. The correlation between the absolute refractive error and AL from every formula were analyzed by Pearson correlation test, respectively.ResultTotal 112 eyes of 83 cataract patients with steep curvature cornea were collected. The anterior chamber depth (ACD) was a covariate in the short AL group in the covariance analysis of absolute refractive error (P<0.001). The SRK/T and Holladay formula had the lowest mean absolute error (MAE) (0.47D), there were statistically significant differences in MAE between the five formulas for short AL group (P = 0.024). The anterior chamber depth had no significant correlation in the five calculation formulas in the normal AL group and long AL group (P = 0.521, P = 0.609 respectively). In the normal AL group, there was no significant difference in MAE between the five calculation formulas (P = 0.609). In the long AL group, Barrett Universal II formula had the lowest MAE (0.35), and there were statistically significant differences in MAE between the five formulas (P = 0.012). Over the entire AL range, the Barrett Universal II formula had the lowest MAE and the highest percentage of eyes within ± 0.50 D, ± 1.00 D, and ± 1.50 D (69.6%, 93.8%, and 98.2% respectively).ConclusionCompared to SRK/T, Haigis, Hoffer Q, and Holladay, Barrett Universal Ⅱ formula is more accurate in predicting the IOL power in the cataract patients with steep curvature cornea ≥ 46.0 diopters.

Predictors of Intraocular Pressure Lowering after Phacoemulsification and iStent Implantation

To explore the demographic and clinical variables associated with intraocular pressure (IOP) lowering after cataract extraction (CE) alone or CE in combination with the iStent (Glaukos Corporation) placement (CE+IS). Retrospective data extraction and survival analysis of consecutive patients identified over a 2-year period. Patients with mild to moderate glaucoma who underwent CE (48 eyes of 32 patients) or CE+IS (61 eyes of 37 patients) were analyzed. Inability to reduce the number of medications or the IOP by at least 20% compared with baseline on 2 consecutive visits was considered surgical failure. Using Cox proportional hazards models, survival analysis was performed, and demographic and clinical variables were evaluated as risk factors. Time to failure after surgical procedure. CE+IS had lower odds of failure than CE alone (hazard ratio [HR], 2.01; P= 0.047). In White patients, CE+IS showed greater odds of success compared with CE alone (HR, 2.86; P= 0.007). For non-White patients, no difference was found in the outcomes for the 2 procedures (HR, 0.59; P= 0.48). In the multivariate analysis, non-White race (HR, 8.75; P= 0.0002) and longer axial length (HR, 1.61; P= 0.03) were associated with greater hazard of failure after CE+IS. In the CE group, greater odds of failure were associated with steeper corneal curvature (HR, 1.74; P= 0.008), shallower anterior chamber (HR, 0.22; P=0.008), and longer axial length (HR, 1.58; P= 0.01). Addition of the iStent to CE improved the duration of IOP lowering in White patients, but not in non-White patients. Associations between IOP lowering after CE and biometric parameters may allow for leveraging these clinical parameters for better case selection for these procedures.

Development of a new intraocular lens power calculation method based on lens position estimated with optical coherence tomography

A new method is developed and validated for intraocular lens (IOL) power calculation based on paraxial ray tracing of the postoperative IOL positions, which are obtained with the use of anterior segment optical coherence tomography. Of the 474 eyes studied, 137 and 337 were grouped into training and validation sets, respectively. The positions of the implanted IOLs of the training datasets were characterized with multiple linear regression analyses one month after the operations. A new regression formula was developed to predict the postoperative anterior chamber depth with the use of the stepwise analysis results. In the validation dataset, postoperative refractive values were calculated according to the paraxial ray tracing of the cornea and lens based on the assumption of finite structural thicknesses with separate surface curvatures. The predicted refraction error was calculated as the difference of the expected postoperative refraction from the spherical-equivalent objective refraction values. The percentage error (within ±0.50 diopters) of the new formula was 84.3%. This was not significantly correlated to the axial length or keratometry. The developed formula yielded excellent postoperative refraction predictions and could be applicable to eyes with abnormal proportions, such as steep or flat corneal curvatures and short and long axial lengths.

Anterior Chamber Angle, Intraocular Pressure, and Globe Biometric Parameters in the Children with β-Thalassemia Major.

ABSTRACTBackgroundTo evaluate the intraocular pressure (IOP), anterior chamber angle (ACA), and globe biometric parameters in β-thalassemia major children and the correlations of these changes.Materials and methodsEighty-four eyes were included (42 eyes of thalassemia patients and 42 eyes of control). All participates underwent head circumference and height measurements, full ophthalmic examination, anterior segment optical coherence tomography (AS-OCT), and A-scan biometry.ResultsThe temporal angle of anterior chamber (T-ACA) was significantly narrower in thalassemia patients with p value = 0.008. While the nasal angle showed a nonsignificant narrowing with p value = 0.153. This narrowing was positively correlated with the height, and negatively correlated with the head circumference. Intraocular pressure was statistically higher in thalassemia patients with p value = 0.000. The increased IOP was positively correlated with the head circumference and the lens thickness (LT) and negatively correlated with T-ACA, axial length (AL), vitreous chamber depth (VCD), and anterior chamber depth (ACD). Axial length, ACD, and VCD significantly decreased with p value = 0.000 for all with a positive correlation with the height and a negative correlation with the head circumference. The LT increased in thalassemia group with p value = 0.000. This increase was positively correlated with the head circumference and negatively with the height. Also, there was steeper corneal curvature in thalassemia group with p value = 0.023 and 0.015 (for K1 and K2, respectively). No significant change was observed in corneal thickness in both groups with p value = 0.810.ConclusionNarrower T-ACA, increased IOP, shorter (AL, VCD, and ACD), steeper corneal curvature, and thicker lens were found in thalassemia patients.How to cite this articleEl-Haddad NSM. Anterior Chamber Angle, Intraocular Pressure, and Globe Biometric Parameters in the Children with β-Thalassemia Major. J Curr Glaucoma Pract 2020;14(1):30–36.

Predictors of Myopic Regression for Laser-assisted Subepithelial Keratomileusis and Laser-assisted in Situ Keratomileusis Flap Creation with Mechanical Microkeratome and Femtosecond Laser in Low and Moderate Myopia

ABSTRACTPurpose: To determine the predictive factors of postoperative myopic regression in subjects who have undergone laser-assisted subepithelial keratomileusis (LASEK), laser-assisted in situ keratomileusis (LASIK) with flaps created using a mechanical microkeratome (MM) or LASIK with flaps created using a femtosecond (FS) laser for −0.50 D to −6.0 D myopia.Materials and Methods: This study was designed as a retrospective comparison. We included 236 eyes in the LASEK group, 1,178 eyes in the MM-LASIK group and 1,333 eyes in the FS-LASIK group. Refractive outcomes were recorded at one day; one week; and one, three, six and 12 months postoperatively. Predictors affecting myopic regression and other covariates were estimated using a Cox proportional hazards model for the three methods of surgery.Results: At 12 months, the survival rates (no myopic regression) were 63.36%, 74% and 77% in the MM-LASIK, LASEK, and FS-LASIK groups, respectively. Risk factors for myopic regression were indicated for patients with greater preoperative central corneal thicknesses (CCT) (P = .02), female patients (P < .01), patients with aspherical ablations (P = .01) and those with larger transitional zones (TZ) (P < .01). Among the three surgeries, MM-LASIK had a significantly higher probability of postoperative myopic regression (P < .01). Longer durations of myopia (P = .03), steeper corneal curvatures (Kmax) (P < .01) and larger optical zones (OZ) (P < .01) were protective factors.Conclusion: MM-LASIK had the highest risk for myopic regression. OZ, TZ, aspherical ablations, preoperative corneal curvatures and being a female patient had significant influence on myopic regression in −0.50 D to −6.0 D myopia.

Predictors affecting myopic regression in \u2212\u20096.0D to \u2212\u200910.0D myopia after laser-assisted subepithelial keratomileusis and laser in situ keratomileusis flap creation with femtosecond laser-assisted or mechanical microkeratome-assisted

PurposeTo investigate the predictive factors of postoperative myopic regression among subjects who have undergone laser-assisted subepithelial keratomileusis (LASEK), laser-assisted in situ keratomileusis (LASIK) flap created with a mechanical microkeratome (MM), and LASIK flap created with a femtosecond laser (FS). All recruited patients had a manifest spherical equivalence (SE) from − 6.0D to − 10.0D myopia.MethodsThis retrospective, observational case series study analyzed outcomes of refraction at 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. Predictors affecting myopic regression and other covariates were estimated with the Cox proportional hazards model for the three types of surgeries.ResultsThe study enrolled 496 eyes in the LASEK group, 1054 eyes in the FS-LASIK group, and 910 eyes in the MM-LASIK group. At 12 months, from − 6.0D to − 10.0D myopia showed that the survival rates (no myopic regression) were 52.19%, 59.12%, and 58.79% in the MM-LASIK, FS-LASIK, and LASEK groups, respectively. Risk factors for myopic regression included thicker postoperative central corneal thickness (P ≦ 0.01), older age (P ≦ 0.01), aspherical ablation (P = 0.02), and larger transitional zone (TZ) (P = 0.03). Steeper corneal curvature (Kmax) (P = 0.01), thicker preoperative central corneal thickness (P < 0.01), smaller preoperative myopia (P < 0.01), longer duration of myopia (P = 0.02), with contact lens (P < 0.01), and larger optical zone (OZ) (P = 0.02) were protective factors. Among the three groups, the MM-LASIK had the highest risk of postoperative myopic regression (P < 0.01).ConclusionsThe MM-LASIK group experienced the highest myopic regression, followed by the FS-LASIK and LASEK groups. Older age, aspheric ablation used, thicker postoperative central corneal thickness, and enlarging TZ contribute to myopic regression; steeper preoperative corneal curvature (Kmax), longer duration of myopia, with contact lens, thicker preoperative central corneal thickness, lower manifest refraction SE, and enlarging OZ prevent postoperative myopic regression in myopia from − 6.0D to − 10.0D.