Myopic Eyes Research Articles

Correlation between spherical equivalent and biometry parameters in adult Cynomolgus macaque

To characterize the distribution of refractive and ocular biometry parameters and analyze the effect factors of the refractive status in cynomolgus monkey colonies. A Population-based cross-sectional study was conducted in adult cynomolgus macaque colonies. Animals were anesthetized with Zoletil 50. Intraocular pressure was measured using the Icare tonometer. Cycloplegic refraction (three drops of 1% tropicamide) and corneal radius of curvature (CRC) were measured using an autorefractor. The spherical equivalent (SE) was calculated. Biometric measurements, including the anterior chamber depth (ACD), lens thickness (LT), and axial length (AL), were obtained by A-scan ultrasonography. The AL-to-CR ratio (AL/CRC) was calculated. Central corneal thickness (CCT) and choroidal thickness (ChT) were measured using the Heidelberg Spectralis HRA OCT. Multiple regression analysis was performed to explore the association between refraction and ocular biometry. Among 263 cynomolgus monkeys (aged 5-26 years), which consisted of 520 eyes, 29.42% had hyperopia, 27.12% had emmetropia, 33.27% had mild-to-moderate myopia and 10.19% had high myopia. The mean SE was -1.27±3.44 Diopters (D). The mean CRC, CCT, AL, and ChT was 5.70±0.22mm, 454.30±32.40μm, 18.76±0.89mm and 188.96±38.19μm, respectively. The LT was the thickest in the hyperopic eyes. CRC was the lowest, and CCT was the thickest in high myopic eyes. AL increased, while ChT decreased as SE decreased. For the SE variance, AL alone explained 40.5%; age, AL, and CRC together explained 57.5%. The refractive characteristics and biometry parameters of cynomolgus monkeys are highly comparable to those of humans. AL, CRC, and ChT showed the similar variation tendency in cynomolguses when compared to humans. Cynomolgus monkeys with naturally-occurring refractive errors may be a good animal model for refractive studies.

Rare case of accommodative loss after barrage laser in myopic eyes and the novel method of rehabilitation using topical pilocarpine

Accommodation is mediated by the short posterior ciliary nerves (SPCN) through muscarinic innervation to ciliary muscles. We report a case of an 18-year female who presented with glare and loss of near vision in both eyes after barrage laser to the peripheral retina for multiple lattices with atrophic holes. Before laser, both eyes (OU) best corrected visual acuity (BCVA) with myopic correction was 20/20. After 1 week post-laser, near vision decreased to OU N18, and pupils were dilated and sluggishly reacting. A working diagnosis of bilateral accommodative and pupillary paralysis secondary to laser-induced damage to SPCN was made. We rehabilitated her with topical 1% pilocarpine drops for a month and she recovered. This is one of the few case reports of internal ophthalmoplegia following a barrage laser in a myopic patient. Another uniqueness is the use of 1% pilocarpine drops as a temporary rehabilitation for near vision correction.

Vertical rotation of phakic intraocular lens to achieve optimal vaulting in a myopic eye

Optimal implantable collamer lens (ICL) sizing and normal postoperative ICL vault are important to avoid adverse events. Spherical phakic intraocular lens (PIOL) implantation was done for a case of both eye myopia. Both eyes had similar ocular biometry, hence the same size PIOL was ordered. The right eye had postoperatively, a high posterior vault of 2000 μ on POD1, which reduced to 1000 μ on POD2. Re-evaluation confirmed similar ocular and PIOL parameters in both eyes. The PIOL was rotated 90° to a vertical rotation after which a reduction in the vault from 1000 to 700 μ was achieved. Satisfactory refractive outcome and optimal vault were maintained during subsequent visits. The left eye course was uneventful.

Secondary add-on IOL implantation for pseudophakic residual ametropia in high myopes – A case series

High Myopic cataract patients receiving low-powered or negative powered intraocular lenses (IOLs) after phacoemulsification, often have residual hyperopic refractive errors and remain dissatisfied. Implantation of add-on IOL is one of the easy options to address this issue. We present three such cases of refractive surprise following cataract surgery in highly myopic eyes, who, after implantation of monofocal hydrophilic acrylic sulcus fixated add-on IOL in the presence of the primary IOL in the bag, had 6/9 unaided vision without any perioperative complications. Secondary sulcus fixated add-on IOL implantation is a safe and effective procedure to correct refractive surprise following phacoemulsification cataract surgery in high myopes.

Anatomical and optical parameters and aberrations of the optical system of the eye in anisometropic myopia

Purpose: to compare anatomical and optical parameters and aberrations of both eyes in patients with acquired and congenital anisometropic myopia.Material and methods. 22 patients (44 eyes) aged 18–35 (averagely, 25.2) with acquired and congenital anisometropic myopia were examined using the Galilei G6 optical eye system analyzer (Ziemer, Switzerland). The analysis of total, corneal and internal aberrations of the eye was carried out on an OPD-Scan III (Nidek) aberrometer.Results. In both groups with acquired and congenital anisometropic myopia, the axial length of the higher myopic eye was greater than that of the fellow eye. A greater asphericity and higher astigmatism of the cornea were revealed in higher myopic eyes of patients with congenital myopia as compared to acquired myopia. The total RMS HOA in congenital myopia was significantly greater in the higher myopic eye compared to the fellow eye (1.07 D and 0.68 D, respectively) and greater than in cases of acquired myopia. All HOA were greater in higher myopic eyes as compared to the fellow ones in cases of congenital myopia. In case of acquired myopia only the total coma appeared to be greater in the higher myopic eye. Corneal aberrations in acquired anisometropic myopia did not differ in the paired eyes. In case of congenital myopia, the total tilt was significantly greater in the higher myopic eye, and total coma and spherical aberration have lower values, even with a transition to negative ones (p < 0.05).Conclusion. The revealed differences of the wavefront of the eyes with anisometropic congenital and acquired myopia are rather a consequence of anatomical and optical differences (the axial length of the eyes and the topography of the cornea), than the cause of anisometropia.

Comparisons of the protein expressions between high myopia and moderate myopia on the anterior corneal stroma in human.

To investigate the differentially expressed proteins (DEP) between high myopia and moderate myopia on the anterior corneal stroma. Tandem mass tag (TMT) quantitative proteomics was utilized to reveal proteins. DEPs were screened by the multiple change of more than 1.2 times or less than 0.83 and the P value < 0.05. The DEPs were functional annotated by Gene Ontology (GO) terms. Proteins and protein interaction (PPI) networks were conducted with String online tool. Parallel reaction monitoring (PRM) data processing was used to verify the TMT proteomics results. There are 36 DEPs between high myopia and moderate myopia on the anterior corneal stroma, of which 11 proteins are upregulated, 25 proteins are downregulated. The GO analysis demonstrated keratinocyte migration and structural constituent of cytoskeleton that are significantly changed with most of the proteins decreased in high myopic corneas. Keratin 16 (KRT16) and erythrocyte membrane protein band 4.1-like protein 4B are the only two proteins involved in both functions. The PPI analysis showed keratin type II cytoskeletal 6A (KRT6A) and KRT16 that have strong connections. Immunoglobulin lambda variable 8-61(IGLV8-61) and nicotinamide phosphoribosyl transferase (NAMPT) have consistent results with the TMT. The high myopic corneas have 36 DEPs compared to the moderate myopic corneas on the anterior corneal stroma. Keratinocyte migrations and structural constituent of cytoskeleton are weakened in high myopic corneas, which may partly account for the lower corneal biomechanics in high myopic eyes. The lower expressed KRT16 plays important roles in high myopic corneas.

Classification of Myopia Levels using Deep Learning Methods on Fundus Image

Disorders of the eye or also known as eye disease is a condition that can affect vision for some people in their lifetime. There are 40 types of eye disorders or eye diseases, one of which is Myopia. Myopia is a visual disturbance that causes objects that are far away to appear blurry, but there is no problem seeing objects that are near. Myopia or nearsightedness is also known as minus eye. From this description, it is very important to conduct research in detecting eye diseases before the increase in eye minus and blindness. This study aims to classify myopic eye disease using the Deep Learning method with several different architectures, namely the VGG16, VGG19 and InceptionV3V3 models. Where the first is to distinguish normal and abnormal while the other is to classify with Augmented myopia image dataset and non augmented myopia image dataset obtained from the Retinal Fundus Multi-Disease Image Dataset (RFMID). In the implementation of the Deep Learning method using 20 Epochs. The results of the accuracy of the classification of eye diseases using the non augmented myopia image dataset are 66.0% for the VGG16 architectural model, then 95.99% for the VGG19 architectural model and 93.99% for the InceptionV3 architectural model and the accuracy results using the Augmented myopia image dataset are 97.53% for the VGG16 architectural model, 97.53% for the VGG19 architectural model and 99.50% for the InceptionV3 architecture model.

Intraocular complement activation is related to retinal vascular and neuronal degeneration in myopic retinopathy.

To investigate the relationship between the intraocular levels of complement proteins and myopia-related retinal neuronal and vascular degeneration. Aqueous humour from 147 myopic patients, including 60 low-myopia and 87 high-myopia were collected during Implantable Collamer Lens implantation surgery. All participants received comprehensive ophthalmic examinations, including logMAR best corrected visual acuity, axial length measurement, fundus photography and ocular B-scan ultrasonography. The myopic eyes were further classified into simple myopia (SM, n = 78), myopic posterior staphyloma (PS, n = 39) and PS with myopic chorioretinal atrophy (PS + CA, n = 30). Retinal thickness and vascular density in the macula (6 mm × 6 mm) and optic nerve head (4.5 mm × 4.5 mm) were measured using Optical Coherence Tomography (OCT) and OCT angiography (OCTA). The levels of complement proteins including C1q, C3, C3b/iC3b, C4, CFB, CFH, C2, C4b, C5, C5a, CFD, MBL and CFI in the aqueous humour were measured using the Luminex Multiplexing system. The real-time RT-PCR was conducted to examine the expression of complement genes (C1q, C2, C3, C4, CFI and CFD) in the guinea pig model of long-term form deprivation-induced myopic retinal degeneration. OCTA showed that retinal neuronal thickness and vascular density in superficial and deep layers of the macular zone as well as vascular density in the optic nerve head were progressively decreased from SM to PS and PS + CA (p < 0.05). The aqueous humour levels of C1q, C3, C3b/iC3b, C4, CFB, CFH, C2, C4b, C5 and CFI were significantly higher in high-myopic eyes compared to those in low-myopic eyes. Further subgroup analysis revealed the highest levels of complement components/fragments in the PS + CA group. The intraocular levels of complement factors particularly C3b/iC3b and C4 were negatively correlated with macular zone deep layer retinal thickness and vascular density and optic nerve head vascular density. The expression of C2, C3 and C4 genes was significantly higher in guinea pig eyes with myopic retinal degeneration compared to control eyes. The intraocular classical pathway and alternative pathway of the complement system are partially activated in pathological myopia. Their activation is related to the degeneration of retinal neurons and the vasculature in the macula and the vasculature in the optic nerve head.

Association between choriocapillaris perfusion and axial elongation in children using defocus incorporated multiple segments (DIMS) spectacle lenses.

To investigate choroidal and ocular biological variables that influence axial length (AL) elongation in children wearing defocused incorporated multiple segments (DIMS) spectacle lenses. This cohort study included 106 myopic children aged 7-14 years with a 1-year follow-up. Participants were divided into two groups according to the increase in AL in one year: rapid (>0.2 mm) and slow (≤0.2 mm) axial elongation groups. Cycloplegic autorefraction and AL were measured at baseline and after 6 and 12 months. The area of choriocapillaris flow voids (FVs) and choroidal thickness (ChT) at baseline were measured. Univariate linear regression analysis showed that AL elongation were significantly associated with the FVs area (standardised β = 0.198, P < 0.05) and age (standardised β = -0.201, P < 0.05). Multiple linear regression showed that the FVs area, age, and average K reading were associated with AL elongation. Multiple logistic regression analyses showed that greater degrees of myopia and larger FVs areas were risk factors for rapid axial elongation, while older age, large pupil diameter and steeper cornea were protective factors. In estimating axial elongation, the FVs area alone demonstrated an area under the curve (AUC) of 0.672 (95% CI, 0.569-0.775, P < 0.01), and that of FVs area and other ocular variables was 0.788 (95% CI, 0.697-0.878, P < 0.001). Larger choriocapillaris FVs area at baseline may help to predict axial elongation in myopic eyes. The association between FVs area and axial elongation should be taken into consideration in further myopic cohort studies.

Posterior scleral birefringence measured by triple-input polarization-sensitive imaging as a biomarker of myopia progression.

In myopic eyes, pathological remodelling of collagen in the posterior sclera has mostly been observed ex vivo. Here we report the development of triple-input polarization-sensitive optical coherence tomography (OCT) for measuring posterior scleral birefringence. In guinea pigs and humans, the technique offers superior imaging sensitivities and accuracies than dual-input polarization-sensitive OCT. In 8-week-long studies with young guinea pigs, scleral birefringence was positively correlated with spherical equivalent refractive errors and predicted the onset of myopia. In a cross-sectional study involving adult individuals, scleral birefringence was associated with myopia status and negatively correlated with refractive errors. Triple-input polarization-sensitive OCT may help establish posterior scleral birefringence as a non-invasive biomarker for assessing the progression of myopia.

Effects of orthokeratology lenses on tear film and tarsal glands and control of unilateral myopia in children.

Introduction: To investigate the effects of an orthokeratology lens on the tear film and tarsal glands and myopia control in children with unilateral myopia using an intelligent analysis model. Methods: We retrospectively reviewed the medical records from November 2020 to November 2022 of 68 pediatric patients with unilateral myopia in Fujian Provincial Hospital who had been wearing an orthokeratology lens for more than 1year. The 68 myopic eyes were included in the treatment group, while the 68 healthy, untreated contralateral eyes were included in the control group. Tear film break-up times (TBUTs) were compared between the two groups at various intervals, and an intelligent analysis model was used to compare the deformation coefficients of 10 meibomian glands in the central area and the different positions of the glands in the two groups after 12months of treatment. Changes in axial length and equivalent spherical power were also compared between the groups before and after 12months of treatment. Results: In the treatment group, TBUTs differed significantly between 1 and 12months after treatment, although no significant differences from baseline were observed at 3 or 6months. No significant differences in TBUTs were observed at any time point in the control group. After 12months of treatment, significant between-group differences were observed for glands 2, 3, 4, 5, 6, 7, 8, and 10 (numbered from the temporal to nasal regions). The treatment group also exhibited significant differences in deformation coefficients at different detection positions in the central region, with glands 5 and 6 exhibiting the highest deformation coefficients. Increases in axial length and equivalent spherical power were significantly greater in the control group than in the treatment group after 12months of treatment. Discussion: Wearing orthokeratology lenses at night can effectively control myopia progression in children with unilateral myopia. However, long-term use of these lenses may lead to meibomian gland deformation and impact tear film function, and the extent of deformation may vary at different positions in the central region.

Expansile gas kinetics for pneumatic retinopexy.

To study the behaviour of expansile intravitreal gases and air used in treating rhegmatogenous retinal detachment. A validated mathematical model of gas expansion and absorption in human eyes was used to simulate the effect of varying volumes of pure air, SF6, C2F6 and C3F8 injected into the vitreous cavity. Variation in axial length was accounted for by using three different vitreous cavity volumes to represent hypermetropic, emmetropic and myopic eyes. The time course of varying volumes of pure air and fluorinated gases injected into the vitreous cavity were tabulated, with calculated parameters including volume of gas, percentage gas fills and corresponding retinal contact angles at different time points. We produced a comprehensive compilation of expansive gas kinetics aiming to facilitate surgeon selection of the most suitable choice of gas and volume to use, tailored to an individual patient's clinical need.

Optical quality with ocular aberrations in young myopic eyes with machine learning

Objective: The objective of this retrospective study was to employ machine learning techniques to examine age-related traits of ocular aberrations in a substantial population with myopia and myopic astigmatism. Methods: This was a cross-sectional study. Data from a population of myopic and myopic astigmatism patients who underwent wavefront aberration examinations at the Refractive Surgery Center of Tianjin Eye Hospital in Tianjin, China, were collected continuously from January 2013 to July 2017. The data from the right eye of each individual were collected for analysis. Each eye had 32 outcome data points, including age, best-corrected visual acuity (BCVA), lower-order aberrations (spherical diopter, cylindrical diopter, and astigmatic axis), and higher-order aberrations [Zernike coefficients and root mean square (RMS) of the third to sixth order aberrations] were analyzed. Higher-order aberrations were measured by Hartmann-Shack aberrometer. Results: The study included 1 507 subjects (1 507 eyes), comprising of 694 males and 813 females, with a mean age of (23.28±5.45) years. The findings demonstrated a decrease followed by an increase in most of the higher-order aberrations with age between 15-40 years. The minimum value points were observed in the age group of 25-30 years for RMS of total higher-order aberrations, 3rd RMS (with a confidence of 47.74% for range 1), 4th RMS (with a confidence of 86.01% for range 1), and trefoil aberrations (with a confidence of 56.38% for C33 and 73.25% for C3-3). The minimum value points were also observed in the age group of 30-35 years for primary spherical aberration (with a confidence of 56.10% for C40) and vertical coma-like aberration (with a confidence of 56.91% for C3-1). In contrast, astigmatism with the rule tended to decrease with age, while astigmatism against the rule and oblique astigmatism tended to increase (with a confidence of 88.66%, 84.71%, 81.07%, 79.67%, and 66.35% for astigmatism with the rule in different age groups). Conclusions: As age increases, the population with with-the-rule astigmatism decreases while the population with against-the-rule astigmatism increases. The high-order aberrations are the lowest in the 25-35 age group.

Microvasculature and microstructure alteration in dry-type high myopia.

To investigate the alterations in the retinal vasculature and microstructure in dry-type high myopia. One hundred and eighty-nine dry-type high myopia eyes were classified into three groups. Group 1 consisted of 86 eyes with no myopic retinal degenerative lesion (C0). Group 2 consisted of 71 eyes with tessellated fundus (C1). Group 3 consisted of 32 eyes with diffuse chorioretinal atrophy (C2). Retinal vascular density and retinal thickness were measured with optical coherence tomography angiography. The scanning area was a 3 × 3 mm2 ring with the fovea of the macular. All data were analyzed with the SPSS 23.0 by one-way ANOVA test among comparison groups. Pearson's correlation analysis was used to determine the relations among measurements. Univariate linear regression showed a correlation between the vascular densities and retinal thicknesses. The microvessel density significantly decreased and significant thinning of the superior and temporal macular thickness in the C2 group. The vascular densities of macular decreased significantly with the increase of axial length (AL) and refractive diopter in the C2 group. The retinal thicknesses of the macular fovea increased significantly with the increase of vascular densities in the C0 group and C1 group. The impairment of retinal microstructure is more likely related to reduced oxygen and nutrients due to microvessel density decreases.

Short-Term Axial Length Changes in Myopic Eyes Induced by Defocus Spectacles for Myopia Control

Background. This study tested short-term axial length changes with Lenstar using a simple peripheral plus-add spectacle design. Methods. The subjects for this study were current users of monofocal glasses or contact lenses, aged 18–25 years, with myopic spherical refractions ranging from −1.00 to −5.00 diopters in both eyes. This study tested subjects while using a pair of special defocus spectacles that possess a central zone with the distance myopic correction and a peripheral zone with +3.50 added diopters. The procedure consisted of reading an online book with black letters on white background on a desktop computer, in two periods—one with the usual spectacles and the second with special defocus spectacles. Before and after these periods, 10 axial length measurements of the right eye were made with Lenstar and averaged up to three decimal points. Results. Seventeen subjects (thirteen female and four male; mean age 22.3 ± 5.5 years) participated in this study. The mean spherical equivalent of their right eye was −2.31 ± 1.06 diopters. There was a significant difference of +8.1 microns which increased the axial length from baseline when reading the usual prescription levels during the first 40 min period. When subjects read in the same situation with the defocus spectacles, the axial length significantly returned to baseline measurements, which were shortened by −10.6 microns. Conclusions. The decrease in axial length with these spectacles might indicate an effect on axial elongation signals from the choroid. These spectacles could be tested for myopia control purposes.

Long-term variations and influential factors of the treatment zone of wearing orthokeratology lenses

PurposeTo investigate the variation trend of the treatment zone (TZ) during 12 months of Orthokeratology (Ortho-K) from the perspective of the treatment zone size (TZS), decentration (TZD) and the weighted Zernike defocus coefficient of the treatment zone (Cweighteddefocus). Methods94 patients were included in this retrospective study, who were fitted with a 5-curve vision shaping treatment (VST) lens (n = 44) or a 3-zone corneal refractive therapy (CRT) lens (n = 50). The TZS, TZD and Cweighteddefocus up to 12 months were analyzed. ResultsTZS (F(4,372) = 10.167, P＜0.001), TZD (F(4,372) = 8.083, P＜0.001) and Cweighteddefocus (F(4,372) = 7.100, P＜0.001) were significantly increased with time during overnight Ortho-K treatment. The TZS increased sharply from 1 week to 1 month of overnight Ortho-K (F = 25.479, P <.001) and stayed smooth then. It showed growing tendency from 6 to 12 months (F = 8.407, P =.005). The TZD (F = 16.637, P <.001) and Cweighteddefocus (F = 13.401, P <.001) increased significantly until 1 month and kept stable until 12 months (all P＞0.05). The univariant linear regression analysis showed that TZS of the last visit was correlated with baseline myopia (β = 0.219, P =.034). Also, the greater final Cweighteddefocus was correlated with higher baseline myopia (β = -0.589, P＜0.001) and higher corneal astigmatism (β = -0.228, P =.007) at the onset of lens wear with the multiple linear regression. ConclusionThe TZS, TZD and Cweighteddefocus kept stable after 1 month of Ortho-K while the TZS had an increasing trend after 6 months. Children with higher myopic eyes or higher corneal astigmatism at baseline tended to have smaller TZS and greater Cweighteddefocus at 12 months.

The Mechanosensitive Piezo1 Channel Mediates Mechanochemical Transmission in Myopic Eyes.

To identify the expression of the mechanosensitive ion channel Piezo1 in the retina of guinea pigs with form deprivation myopia (FDM) and to investigate mechanisms by which Piezo1 channels might regulate myopia. Sixty 3-week-old guinea pigs were divided into four groups randomly: normal control, FDM, FDM + vehicle control (DMSO), and FDM + Piezo1 inhibitor (GsMTx4). Measurements of spherical equivalent (SE) and axial length (AL) of the guinea pig were taken using retinoscopy and A-scan ultrasound examination, respectively. Location of Piezo1 protein was determined using immunohistochemistry. The histological structure and thickness changes of the guinea pig retina were observed by hematoxylin and eosin. Expression of Piezo1 in the retina was detected using quantitative RT-PCR and Western blot. Reactive oxygen species (ROS) levels in the retina were measured using flow cytometry. After 4 weeks of form deprivation, the FDM group exhibited a significantly increased myopic degree and axial length compared with the normal control group (all P < 0.001), and had higher expression levels of Piezo1 and ROS than the normal control group (P < 0.001 and P = 0.002, respectively). Piezo1 protein expression was down-regulated in guinea pigs given GsMTx4 compared with the DMSO group (P = 0.037). Additionally, the GsMTx4 group showed lower myopic degree (P < 0.001) and lower ROS levels (P = 0.019) compared with the DMSO group. The Piezo1 channel may be activated in the retinas of FDM guinea pigs and be involved in the development of myopia by regulating intraocular ROS levels.

Repeatability and Agreement between Scansys and Pentacam in Ocular Biological Parameters.

To assess the repeatability and agreement between Scheimpflug-based corneal topography, Scansys and Pentacam, in measuring ocular parameters in myopic eyes. A Grade-A tertiary hospital in Beijing, China. Cross-sectional study. The following measurements were performed in 204 patients undergoing pre-operative examinations for refractive surgery from the corneal curvature, astigmatism, corneal thickness, corneal volume, corneal asphericity, anterior chamber depth and volume, and pupil diameters. Repeatability was determined using intraclass correlation coefficient (ICC) with 95% confidence interval (95% CI), Cronbach's Alpha, coefficient of variation (CV), within-subject standard deviation (Sw), test-retest repeatability (TRT), and one-way analysis of variance (one-way ANOVA). The inter-device agreement was determined using paired t-test and Bland-Altman plots. Scansys showed good repeatability in the anterior and posterior corneal flattest meridian (Kf), steepest meridian (Ks), and mean (Km), axis of anterior corneal Ks, anterior corneal astigmatism, pupil central corneal thickness, central corneal thickness, corneal apex thickness, thinnest corneal thickness, corneal volume, photopic pupil diameter, anterior chamber depth and volume. In the agreement study, Bland-Altman plots showed that 95% LoA of corneal curvature, pupil central corneal thickness, corneal apex thickness, thinnest corneal thickness, and corneal volume generated by Scansys and Pentacam were narrow. There were no statistically significant differences in the anterior corneal Kf and Km. Scansys showed good repeatability in measuring corneal curvature of anterior and posterior surfaces, anterior corneal astigmatism, corneal thickness, corneal volume, photopic pupil diameter, anterior chamber volume and depth. Scansys and Pentacam can only be used interchangeably in measuring anterior corneal curvature.

The Zhu-Lu formula: a machine learning-based intraocular lens power calculation formula for highly myopic eyes

BackgroundTo develop a novel machine learning-based intraocular lens (IOL) power calculation formula for highly myopic eyes.MethodsA total of 1828 eyes (from 1828 highly myopic patients) undergoing cataract surgery in our hospital were used as the internal dataset, and 151 eyes from 151 highly myopic patients from two other hospitals were used as external test dataset. The Zhu-Lu formula was developed based on the eXtreme Gradient Boosting and the support vector regression algorithms. Its accuracy was compared in the internal and external test datasets with the Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO) 2.0, Kane, Pearl-DGS and Radial Basis Function (RBF) 3.0 formulas.ResultsIn the internal test dataset, the Zhu-Lu, RBF 3.0 and BUII ranked top three from low to high taking into account standard deviations (SDs) of prediction errors (PEs). The Zhu-Lu and RBF 3.0 showed significantly lower median absolute errors (MedAEs) than the other formulas (all P < 0.05). In the external test dataset, the Zhu-Lu, Kane and EVO 2.0 ranked top three from low to high considering SDs of PEs. The Zhu-Lu formula showed a comparable MedAE with BUII and EVO 2.0 but significantly lower than Kane, Pearl-DGS and RBF 3.0 (all P < 0.05). The Zhu-Lu formula ranked first regarding the percentages of eyes within ± 0.50 D of the PE in both test datasets (internal: 80.61%; external: 72.85%). In the axial length subgroup analysis, the PE of the Zhu-Lu stayed stably close to zero in all subgroups.ConclusionsThe novel IOL power calculation formula for highly myopic eyes demonstrated improved and stable predictive accuracy compared with other artificial intelligence-based formulas.

Accuracy of Haigis Formula Using Total Keratometry for IOL Power Calculation in Eyes with Previous Myopic and Hyperopic LASIK and PRK

Background: this retrospective study aimed to analyze the results of the combination of the Haigis formula and total keratometry (TK) in calculating the IOL power in eyes with previous corneal refractive surgery. Methods: the TK value provided by the IOL Master 700 (Carl Zeiss Meditec) was introduced into the Haigis formula; the mean prediction error (PE), mean absolute error (MAE), median absolute error (MedAE) and percentage of eyes with a PE within ±0.25 D, ±0.5 D, ±0.75 D and ±1.00 D were calculated. Results: ninety-three eyes of 93 patients with previous laser refractive surgery were evaluated. Two groups were defined: the Myopic Group included 51 previously myopic eyes and the Hyperopic Group included 42 previously hyperopic eyes. The mean PE in the Myopic Group was +0.09 ± 0.44 D and 76.47% of eyes had a PE within ±0.50 D. In the Hyperopic Group, the mean PE was −0.15 ± 0.46 D and 66.67% of eyes had a PE within ±0.50 D. Discussion: when compared to the results previously published with other formulas or methods, the Haigis formula combined with TK provided very accurate refractive outcomes for IOL power calculation in eyes with prior myopic and hyperopic corneal refractive surgery. In such eyes the results are similar to or better than those reported in previous studies.