Lenstar LS Research Articles

Analysis of biometric parameters of 2340 eyes measured with optical biometer Lenstar LS900 in a Caucasian population.

To describe the pattern and mutual relationships between basic biometric characteristics of the eye in a Central European Caucasian population. A single-centre retrospective study of 2340 patients (965 males, 1375 females) scheduled for cataract surgery between 2014 and 2016. Measurements using laser interferometry included AL (axial length), K (average corneal curvature), ACD (anterior chamber depth), LT (lens thickness), CCT (central corneal thickness), AST (astigmatism) and WTW (white to white). Subjects were stratified by gender and controlled for age. Descriptive, correlation and regression analyses were performed on the data. The mean AL was 23.33 ± 1.01 mm - higher in males (23.59 ± 0.99 mm), in comparison to females (23.15 ± 0.99 mm). The elderly had lower ACD and higher LT, while males had higher AL independent of age. Furthermore, LT and K decreased with AL, while ACD decreased with LT and increased with AL independent of age and gender. The estimates of the biometrics are obtained on a large sample of subjects and can serve as normative values for Lenstar LS900 in the Central European Caucasian population.

Intra-ocular Lens Master V4 versus LenStar LS900 in Intra-ocular Lens Power Calculation and Postoperative Refraction Prediction

Background: The non-contact optical methods are preferable in Intra-ocular Lens (IOL) power calculation as they have higher resolution, better patient tolerance and greater acceptability. Aim: to compare between LENSTAR LS900 and IOL Master V4 in IOL power calculation. Material and Methods: This prospective comparative study included 60 eyes of 40 cataract patients. Patients with immature cataract of any age and both genders were included while those with dense cataract, media opacities, previous ocular diseases or surgeries or intraoperative complications were excluded. Patients were assessed by a complete comprehensive ophthalmic evaluation. Each patient was evaluated twice, one by the IOL Master and the other by the LENSTAR LS900. Outcome measures were axial length (AL), vertical keratometric dioptric power (K1), horizontal keratometric dioptric power (K2), and IOL power measurements. Results: The mean age of the patients was 67.08 ± 5.34 years. Thirty-five patients were males and 25 were females. The IOL master and LENSTAR were similar (p>0.05) in terms of the AL (24.82 ± 2.21and 24.80 ± 2.20), K1 (43.13 ± 1.66 and 43.14 ± 1.68), K2 (44.14 ± 1.56 and 44.27 ± 1.52) and IOL power (16.86 ± 5.24 and 16.84 ± 5.26). The target refraction on IOL master was -0.01 ± 0.06 compared with 0.04 ± 0.10 on LenStar. The actual refraction was 0.00 ± 0.33. There were non-significant differences between target and actual refractions on both devices (p>0.05). Conclusion: Both the optical biometers, IOL Master and LENSTAR provide similarly precise biometry and IOL power calculation in cataract patients.

Agreement of Ocular Biometry Measured by LenStar LS 900 and CASIA2 Optical Coherence Tomography

Introduction:The present study aimed to compare the anterior segment measurements between optical low-coherence reflectometry (LenStar LS900) and anterior segment optical coherence tomography (CASIA2 OCT). Methods:A total of 198 right eyes of 198 healthy participants were used for the current study, according to the inclusion and exclusion criteria. Ocular biometry parameters, such as central corneal thickness (CCT), anterior chamber depth (ACD), keratometry, and anterior chamber width (ACW), were measured usingLenStar LS 900 and CASIA2 OCT. The differences and correlations were assessed between these two instruments. The agreement was calculated as the 95% limits of agreement (LoA). Results: Among 198 subjects with a mean age of 29.39±7.88 years who enrolled in the study, 106 individuals (53.5%) were women. The mean CCT values were 531.7±35.25 and 527.3±37.82 µm for LenStar and OCT, respectively (P˂0.0001). The ACD measurements showed 2.92±0.40 and 2.95±0.43 mm for LenStar and OCT, respectively (P=0.0549). The ACW mean values were 12.04±0.52 and 11.79±0.49 mm by LenStar and OCT (P˂0.0001). The 95% LoA between the two instruments were within the ranges of -20.79 to 29.43 µm, -0.50 to -0.43 mm, -0.32 to 0.82 mm, and -0.70 to 0.87 D for CCT, ACD, ACW, and astigmatism, respectively. Conclusion: LenStar and OCT showed to have interchangeable ACD measurements; however, the results of CCT, ACW, and corneal astigmatism measured by these two instruments demonstrated clinically significant differences

Effect of axial length and anterior chamber depth on the peripheral refraction profile.

To evaluate the effect of axial length (AL) and anterior chamber depth (ACD) on peripheral refractive profile in myopic patients compared to emmetropic participants. This cross-sectional study was conducted in right eyes of 58 participants of whom 38 were emmetropic and 20 were myopic. Central and peripheral refraction were measured at 10°, 20°, and 30° eccentricities in nasal and temporal fields using an open-field autorefractor. The Lenstar LS900 was used to measure ACD and AL. The participants were divided into three groups of short (<22.5 mm), normal (22.5-24.5 mm), and long eye (>24.5 mm) according to AL and three groups of low ACD (<3.00 mm), normal ACD (3.00-3.60 mm), and high ACD (>3.60 mm) according to ACD. The mean age of the participants was 22.26±3.09y (range 18-30y). The peripheral mean spherical refractive error showed a hypermetropic shift in myopic and emmetropic groups although this shift was more pronounced in the myopic group. The results showed significant changes in the spherical equivalent, J0, and J45 astigmatism in all gazes with an increase in eccentricity (P<0.001). The pattern of refractive error changes was more noticeable in long and short eyes versus normal AL eyes. Moreover, the pattern of peripheral refractive changes was much more prominent in the high ACD group versus the normal ACD group and in the normal ACD group versus the low ACD group. Peripheral refraction changes are greater in participants with AL values outside the normal range and deeper ACD values compared to participants with normal AL and ACD.

Effect of body stature on refraction and ocular biometry in Chinese young adults: The Anyang University Students Eye Study

ABSTRACT Clinical relevance Large‐scale data on the association between body stature with biometry parameters and refraction in young adults facilitates an understanding of myopia development. Taller persons have eyes with more negative refractions, longer axial lengths, deeper anterior chambers, flatter corneas, and higher axial length‐corneal radius ratio. Background To determine the relationship between body stature with ocular biometry and refraction in young adults. Methods This was a cross‐sectional university‐based study of 16‐ to 26‐year‐old students in China. Cycloplegic refraction and corneal curvature were measured using an autorefractor. Ocular parameters, including axial length, anterior chamber depth and lens thickness, were measured using a Lenstar LS900. Data on height and weight were acquired from an annual standardised physical examination and body mass index was calculated. Results Of 7,971 participants examined in the school clinics, 5,657 (71.0 per cent) were available in the analysis. After adjusting for age, gender, parental myopia, time outdoors, near work and weight, each centimetre of height increase was associated with more negative refraction of −0.023-D, a 0.032-mm increase in axial length, a 0.003-mm increase in anterior chamber depth, a 0.008-mm increase in corneal curvature, and a 0.001 increase in axial length‐corneal radius ratio. With regard to weight, a 1-kg heavier person was more likely to have less negative refraction of 0.011-D, a 0.001-mm increase in anterior chamber depth and a 0.002-mm increase in corneal curvature. A similar pattern of significant associations was also found in body mass index. Conclusion Taller, young adults tended to have longer eyes, deeper anterior chambers, flatter corneas, higher axial length‐corneal radius ratio, and more negative refraction, adjusted for potential confounders. In contrast, heavier and higher body mass index persons are more hyperopic. The differences in stature may partially explain the variation in refraction and ocular biometric parameters.

Agreement of keratometric readings measured using rotating Scheimpflug imaging, auto-refractokeratometer, and biograph in eyes with keratoconus.

To determine agreement in keratometric readings obtained using rotating Scheimpflug imaging with Pentacam, biograph with Lenstar LS900, and Topcon KR-8100P auto-keratorefractometer in eyes with different stages of keratoconus. A total of 89 eyes of 58 patients with keratoconus were examined in this study, retrospectively. The eyes were divided into two groups: mild group (group 1: 42 eyes) (Amsler-Krumeich stage 1) and moderate-to-severe group (group 2: 47 eyes) (Amsler-Krumeich stage 2, 3, 4). The keratometric readings measured using the Pentacam Scheimpflug system, Lenstar LS900, and Topcon KR-8100P auto-keratorefractometer were compared between the groups. The effects of the measurements of anterior chamber depth, Q value, axial length, central corneal thickness (CCT), and maximum value of keratometry (Kmax) on the differences of devices for keratometric readings were investigated. The mean values of the keratometric readings obtained using the Lenstar were steeper than with the Pentacam and Topcon, especially in group 2. In group 1, the mean K2 values measured using the Lenstar were significantly steeper than with the Topcon (p < 0.05); however, the devices were accordant for the other keratometric readings. In group 2, there was an agreement between the Pentacam and Topcon for the mean K1 and Km values; however, there were significant differences between the devices for the other values. The Q value and CCT had a negative correlation, and Kmax had a positive correlation with the differences of Lenstar-Pentacam and Lenstar-Topcon (p < 0.01). According to our results, Pentacam-Topcon and Pentacam-Lenstar can be used interchangeably for keratometry in mild stages of keratoconus. The keratometric readings of Lenstar were found steeper than the other devices with increasing grades of keratoconus. None of these devices can be used interchangeably in moderate-to-severe stages of keratoconus.

Lenstar LS 900 versus Pentacam-AXL: analysis of refractive outcomes and predicted refraction

Analysis of refractive outcomes, using biometry data collected with a new biometer (Pentacam-AXL, OCULUS, Germany) and a reference biometer (Lenstar LS 900, HAAG-STREIT AG, Switzerland), in order to assess differences in the predicted and actual refraction using different formulas. Prospective, institutional study, in which intraocular lens (IOL) calculation was performed using the Haigis, SRK/T and Hoffer Q formulas with the two systems in patients undergoing cataract surgery between November 2016 and August 2017. Four to 6 weeks after surgery, the spherical equivalent (SE) was derived from objective refraction. Mean prediction error (PE), mean absolute error (MAE) and the median absolute error (MedAE) were calculated. The percentage of eyes within ± 0.25, ± 0.50, ± 1.00, and ± 2.00 D of MAE was determined. 104 eyes from 76 patients, 35 males (46.1%), underwent uneventful phacoemulsification with IOL implantation. Mean SE after surgery was − 0.29 ± 0.46 D. Mean prediction error (PE) using the SRK/T, Haigis and Hoffer Q formulas with the Lenstar was significantly different (p > 0.0001) from PE calculated with the Pentacam in all three formulas. Percentage of eyes within ± 0.25 D MAE were larger with the Lenstar device, using all three formulas. The difference between the actual refractive error and the predicted refractive error is consistently lower when using Lenstar. The Pentacam-AXL user should be alert to the critical necessity of constant optimization in order to obtain optimal refractive results.

Inter-device measurement variability of vital data parameters for keratorefractive and cataract refractive surgery.

Introduction:The measurements of corneal white-to-white (WTW) diameter and pupil size are critical for decision making in refractive surgery. Currently, automatic measurement of keratometry, corneal WTW, and pupil size are implemented in several ocular devices. The purpose of this study was to examine the agreement between two commonly used devices, an autorefractor and an optical biometer, for these parameters.Methods:Measurements were performed with both a Lenstar LS-900 and Nidek ARK-1 by an experienced examiner in random order. The devices were placed in close proximity within the same dimly lit room.Results:The measurements of 65 right eyes were analyzed. The results of the flat, steep, and mean keratometric reading were not significantly different (p = 0.96, p = 0.90, p = 0.93, respectively). Corneal WTW distances showed only moderate agreement between devices and were found to be significantly different (r = 0.8071; p < 0.01). Pupil diameters showed poor agreement between devices and were significantly different (r = 0.4890; p < 0.01). Agreement between implantable contact lens sizing, based on the measurements obtained by the two devices, was achieved for 19 of the 51 eyes (37.3%).Conclusion:We found a significant difference in WTW and pupil size measurements between ARK-1 and Lenstar. Results for both of the devices cannot be considered interchangeable for these data parameters.

Slit-lamp measurement of anterior chamber depth and its agreement with anterior segment optical coherence tomography and Lenstar LS 900 in pseudoexfoliation and normal eyes.

Purpose:There is a considerable lack of awareness of slit-lamp measurement of anterior chamber depth (ACD) by the Redmond Smith method (SACD) in present day-to-day clinical practice, which may provide rapid assessment in pseudoexfoliation (PXF) when assessing for angle closure and planning for cataract surgery. This assumes importance not only in outreach clinics but also in the ongoing pandemic caused by the highly contagious novel coronavirus, where social distancing is advocated to contain the spread. We aimed to compare the axial ACD in PXF and normal patients by SACD, and its agreement with the anterior segment optical coherence tomography (ASOCT) and LenstarLS-900.Methods:A prospective comparative observational study was done at a tertiary eye care hospital. A PXF group and a normal group of controls were recruited. All eyes were phakic with normal cornea. Any eye with previous intraocular/refractive surgery and cause of other secondary or uncontrolled glaucoma was excluded. SACD was measured clinically via slit-lamp method and also via ASOCT and Lenstar; agreement between the methodologies was plotted.Results:Fifty patients were recruited in each group. Mean age was 66.82 ± 4.88 years in PXF patients and 65 ± 5.46 years in controls (P = 0.2). ACD was found to be greater in controls compared with the PXF patients; this difference was statistically significant (P < 0.001) across all methodologies. A good agreement with narrow 95% limits of agreement was found between these methodologies.Conclusion:Redmond Smith slit-lamp methodology of estimating the axial ACD is recommended as a rapid, quantifiable, noncontact screening technique during routine examination, especially in primary outreach centers, and is also advantageous during the ongoing pandemic by reducing expendable investigations.

Intraocular lens power calculation formula accuracy: Comparison of 12 formulas for a trifocal hydrophilic intraocular lens.

To evaluate the accuracy of 12 intraocular lens (IOL) power formulas; Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hill-Radial Basis Function (RBF), Hoffer Q, Holladay I, Kane, Ladas Super Formula, Olsen Lenstar, Panacea, Pearl-DGS, Sanders-Retzlaff-Kraff/theoretical (SRK/T). In addition, an analysis of the efficacy as a function of the axial length was performed. About 171 from 93 patients: 68 male eyes and 103 female eyes. Twelve IOL power formula calculations were studied with one IOL platform (trifocal hydrophilic IOL, FineVision Micro F), one biometer (Lenstar LS 900), one topographer (CSO Sirius Topographer), one surgeon, and one optometrist. Optimization were determined to be zeroed mean refractive prediction error. Mean error (ME), mean absolute error (MAE), median absolute error (MedAE) and refractive accuracy within ±1.00 D was calculated. Axial length was split in short and medium eyes. One hundred and seventy eyes were included. Formulas were ranked by percentage within ±0.50 diopters and MAE (D). Among all eyes, Olsen 86.55% (0.273 D) and Barrett Universal II 86.55% (0.285D). For short eyes (<22.5 mm), Olsen 90.70% (0.273 D) and Kane 90.70% (0.225 D). For medium eyes, Barrett 89.34% (0.237 D) and Pearl 86.89% (0.263 D). Olsen and Barrett formula obtained excellent accuracy for overall eyes. Kane and Olsen formula obtained the best results in short eyes. For medium axial length Barrett formula achieved the best accuracy results.

Comparison of an upgraded optical biometer with 2 validated optical biometers.

The Revo NX is a new optical biometer, based on spectral-domain optical coherence tomography and able to obtain high-definition scans of both the anterior and posterior segment of the eye. A previous study found that its measurements of axial length (AL) were not interchangeable with those provided by a validated optical biometer; so, the manufacturer updated the instrument to improve agreement of AL values. This study aimed to prospectively compare the measurements by the updated Revo NX (version 9.5.0, biometry module) with those by 2 validated devices, the IOLMaster 700 and Lenstar LS-900. Optopol Technologies, Zawiercie, Poland. Prospective evaluation of diagnostic test. Comparison between the devices was performed using repeated measures analysis of variance (ANOVA) with Bonferroni posttest, correlation coefficients, and the Bland-Altman method. The investigation evaluated the results of 63 patients. For AL, anterior chamber depth (ACD), and lens thickness (LT), the differences were not clinically significant because they were less than 0.01 mm. Repeated measures ANOVA, however, detected a statistically significant difference for AL (P < .0001) and central corneal thickness (P < .0001) but not for ACD (P = .0630) or LT (P = .2667). The results obtained with all 3 biometers manifested a high level of agreement in the Bland-Altman analysis and very strong correlation. The measurements by the updated Revo NX had high agreement with the other optical biometers; a clear improvement was detected than the previous analysis between the original Revo NX (version 8.0.3) and the Lenstar LS-900.

Influence of measurement differences of anterior chamber depth and axial length on lens thickness evaluation in cataract patients: a comparison of two tests

BackgroundThe purpose of this study was to investigate the agreement of lens thickness (LT) measurements made by contact A-scan ultrasonography and Lenstar LS900 as well as the influence of anterior chamber depth (ACD) and axial length (AL) measurement differences on LT measurement in cataract patients in the two techniques.Methods1247 cataract patients (1247 eyes) participated in this retrospective cross-sectional study. Ocular biometric measurements were performed with Lenstar LS900 and A-scan ultrasonography respectively, and the measured results of AL, ACD and LT were compared using Pearson correlation coefficients (r) and Bland-Altman analyses.ResultsBland-Altman analyses showed poor agreement between the A-scan ultrasonography and Lenstar LS900 in measuring AL and ACD. The average difference of LT was 0.01 mm; the consistency limit was − 0.86 mm, 0.88 mm; and 95.27% of datapoints were within the 95% consistency limit. The consistency of LT measurements between the two techniques was poor for those subjects whose ACD or AL values were beyond the 95% consistency limit. Among the subjects whose AL or ACD values measured by A-scan ultrasonography were greater than those measured by Lenstar LS900, 93.33% of them were within the 95% consistency limit, suggesting that the consistency of LT measurement between the two techniques was poor. Of patients whose ACD or AL measured by A-scan ultrasonography were smaller than that of Lenstar LS900, 96.01% of them were within the 95% consistency limit.ConclusionsThere was good agreement of the LT measurements between A-scan ultrasonography and Lenstar LS900, except for the axis deviating from the apparent axis during A-scan ultrasonography. If this error can be avoided, A-scan ultrasonography can replace Lenstar LS900 in LT measurement in cataract patients.

Comparative Analysis of Swept-Source Optical Coherence Tomography and Partial Coherence Interferometry Biometers in the Prediction of Cataract Surgery Refractive Outcomes.

PurposeTo compare the accuracy of pre-operative corneal measurements obtained with four devices, and the refractive outcomes of two optical biometers.SettingPrivate practice.DesignRetrospective.MethodsData taken from biometric measurements on 299 consecutive eyes prior to cataract surgery were retrospectively analyzed using the Argos SS-Optical Biometer and the Lenstar LS900 PCI optical biometer. As part of the standard cataract surgery pre-operative exam, patients also underwent placido disk topography and Scheimpflug tomography. Keratometry, anterior chamber depth, corneal diameter, pupil diameter, central corneal thickness and axial length were all measured. The comparable measurements were compared. Finally, for those eyes where cataract surgery was performed, the post-operative refractive results were compared to the predictive results of the two biometers.ResultsThe SS-OCT Argos was able to measure all eyes, while five eyes could not be measured with the Lenstar LS900 PCI. Axial length measurements were performed only with the Argos and Lenstar devices. The eyes that could not be measured by the Lenstar LS900 PCI included dense grade IV nuclear sclerosis and large posterior subcapsular cataracts. In the primary endpoints, there was strong correlation between the Argos and the Lenstar devices in eyes with an axial length between 20 and 30 mm.ConclusionThe predictive accuracies of the Argos Optical Biometer and Lenstar LS900 PCI are similar, except in medium and long eyes, in which the predictive accuracy of Argos SS-OCT biometry was higher. The Argos system was found easier to use by technicians when compared to the other biometry devices.

Repeatability of biometry measured by three devices and its impact on predicted intraocular lens power.

To compare the repeatability of ocular biometry measured with the LENSTAR LS 900, IOLMaster 700, and Anterion and its impact on predicted intraocular lens (IOL) power. Tertiary eye-care facility in South India. Prospective, observational, cross-sectional study. Eyes diagnosed with cataract had 3 consecutive scans on each biometers. The repeatability was assessed using the within-subject standard deviation (Sw), test-retest repeatability, and coefficient of variation (CoV). The agreement was evaluated with the intraclass correlation (ICC). The IOL power was calculated with the Barrett Universal II formula. The study comprised 127 eyes of 76 patients. The repeatability of all parameters for a given device were excellent (ICC >0.9, low CoV and Sw). The agreement of the parameters between the biometers was very good (range from 0.93 to 0.99). The predicted IOL power differed statistically between the devices (P < .05), but the difference was clinically insignificant between the 3 biometers (ICC >0.99 for repeat calculation of IOL power). All the biometers included in the study had good to excellent repeatability of biometry parameters. The agreement of the predicted IOL power was excellent between the 3 optical biometers.

Age distribution and associated factors of cornea biomechanical parameter stress-strain index in Chinese healthy population

BackgroundTo investigate the new cornea biomechanical parameter stress-strain index (SSI) in Chinese healthy people and the factors associated with SSI.MethodsA total of 175 eyes from 175 participants were included in this study. Axial length was measured with the Lenstar LS-900. Pentacam measured curvature of the cornea and anterior chamber volume (ACV). Cornea biomechanical properties assessments were performed by corneal visualization Scheimpflug technology (Corvis ST). Student’s t-test, one-way ANOVA, partial least square linear regression (PLSLR) and linear mixed effects (LME) model were used in the statistical analysis.ResultsThe mean (±SD) SSI was 1.14 ± 0.22 (range, 0.66–1.78) in all subjects and affected by age significantly after age of 35 (P < 0.05). In LME models, SSI was significantly associated with age (β = 0.526, P < 0.001), axial length (AL) (β = − 0.541, P < 0.001), intraocular pressure (IOP) (β = 0.326, P < 0.001) and steepest radius of anterior corneal curvature (RsF) (β = 0.229, P < 0.001) but not with ACV, biomechanical corrected intraocular pressure (bIOP), flattest radius of anterior corneal curvature (RfF) or central corneal thickness (CCT) (P > 0.05 for each).ConclusionsSSI increased with age after the age of 35. In addition to age, SSI was positively correlated with RsF and IOP, while negatively correlated with AL.

Signals for defocus arise from longitudinal chromatic aberration in chick

Chicks respond to two signals from longitudinal chromatic aberration (LCA): a wavelength defocus signal and a chromatic signal. Wavelength defocus predicts reduced axial eye growth in monochromatic short-wavelength light, compared to monochromatic long-wavelength light. Wavelength defocus may also influence growth in broadband light. In contrast, a chromatic signal predicts increased growth when short-wavelength contrast > long-wavelength contrast, but only when light is broadband. We aimed to investigate the influence of blue light, temporal frequency and contrast on these signals under broadband conditions. Starting at 12 to 13 days-old, 587 chicks were exposed to the experimental illumination conditions for three days for 8h/day and spent the remainder of their day in the dark. The stimuli were flickering lights, with a temporal frequency of 0.2 or 10 Hz, low (30%) or high contrast (80%), and a variety of ratios of cone contrast simulating the effects of defocus with LCA. There were two color conditions, with blue contrast (bPlus) and without (bMinus). Stimuli in the “bPlus” condition varied the amounts of long- (L), middle- (M_) and double (D-) cone contrast, relative to short- (S-) and (UV-) cone contrast, to simulate defocus. Stimuli in the “bMinus” condition only varied the relative modulations of the L + D vs. M cones. In all cases, the average of the stimuli was white, with an illuminance of 777 lux, with cone contrast created through temporal modulation. A Lenstar LS 900 and a Hartinger refractometer were used to measure ocular components and refraction. Wavelength defocus signals with relatively high S-cone contrast resulted in reduced axial growth, and more hyperopic refractions, under low-frequency conditions (p = 0.002), in response to the myopic defocus of blue light. Chromatic signals with relatively high S-cone contrast resulted in increased axial growth and more myopic refractions, under high frequency, low contrast, conditions (p < 0.001). We conclude that the chromatic signals from LCA are dependent on the temporal frequency, phase, and relative contrast of S-cone temporal modulation, and recommend broadband spectral and temporal environments, such as the outdoor environment, to optimize the signals-for-defocus in chick.

Corneal biomechanical properties in myopic eyes evaluated via Scheimpflug imaging

BackgroundTo investigate the biomechanical properties of the cornea in myopic eyes using corneal visualization Scheimpflug technology (Corvis ST). The relationships between the biomechanical properties of the cornea and the degree of myopia were also investigated.Methods265 eyes of 265 subjects were included. Based on spherical equivalent (SE) in diopters (D), participants were divided into four groups: low myopia/control (SE: − 0.50 to − 3.00D), moderate myopia (SE: − 3.00 to − 6.00D), high myopia (SE: − 6.00 to − 10.00D) and severe myopia (SE greater than − 10.00D). Axial length (AL), anterior segment parameters, and corneal biomechanical properties were obtained with the Lenstar LS900, Pentacam HR and Corvis ST, respectively.ResultsMean (±SD) SE was − 7.29 ± 4.31D (range: − 0.63 to − 25.75D). Mean AL was 26.31 ± 1.82 mm (range: 21.87 to 31.94 mm). Significant differences were detected within the four groups in terms of six corneal biomechanical parameters: deformation amplitude (DA), time from start until second applanation (A2-time), length of flattened cornea at the second applanation (A2-length), corneal velocity during the first and second applanation (A2-velocity), time from start to highest concavity (HC-time), and central curvature at highest concavity (HC radius). AL was positively associated with DA whereas negatively associated with A1-velocity and A2-length. SE was positively associated with A2-time, HC-time and A2-velocity, whereas negatively associated with DA. IOP was positively associated with four corneal biomechanical parameters and negatively associated with three parameters.ConclusionsEyes with severe myopia showed greater DA, lesser A2 time, HC time, and faster A2-velocity compared to low to high myopia. This suggests the cornea becomes weaker and more deformable with elongation of axial length with corresponding increases in myopia. DA, A2-time and A2-velocity could be useful corneal biomechanical indicators in patients with myopia.

Short-term effects of atropine combined with orthokeratology (ACO) on choroidal thickness

PurposeTo analyse the one-month change in subfoveal choroidal thickness (SFChT) of myopic children treated with 0.01 % atropine, orthokeratology (OK), or their combination. MethodsThis is a prospective, randomized controlled trial. One hundred fifty-four children aged between 8 and 12 years with a spherical equivalent (SE) of -1.00 to -6.00 diopters were enrolled. Subjects were randomly assigned to receive 0.01 % atropine and orthokeratology (ACO, n = 39), 0.01 % atropine and single vision glasses (atropine, n = 42), orthokeratology and placebo (OK, n = 36), or placebo and single vision glasses (control, n = 37). SFChT was assessed using optical coherence tomography (OCT). Ocular parameters, including axial length (AL), were measured using a Lenstar LS 900. ResultsSFChT significantly increased in the ACO (14.12 ± 12.88 μm, p < 0.001), OK (9.43 ± 9.14 μm, p < 0.001) and atropine (5.49 ± 9.38 μm, p < 0.001) groups, while it significantly decreased in the control group (-4.81 ± 9.93 μm, p = 0.006). The one-month change in SFChT was significantly different between the control and treatment groups (p < 0.001). The results of pairwise comparisons among the treatment groups showed that the magnitude of the SFChT change was larger in the ACO group than in the atropine group (p = 0.002). The changes in the ACO and OK groups were not significantly different (p = 0.326). ConclusionThe combination of OK and atropine induced a greater increase in SFChT than monotherapy with atropine, which might indicate a better treatment effect for childhood myopia control.

Biometric and refractive errors evaluation in patients with neurofibromatosis type 1.

To analyze biometric changes and prevalence of refractive in patients with neurofibromatosis type 1 (NF1). Retrospective, case-controlled study involving patients affected by NF1 and healthy control subjects. Data on biometric measurements such as axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), keratometry (K1 and K2) values, and white-to-white (WTW), obtained by use of optical low-coherence reflectometry on a Lenstar LS 900® (Haag-Streit AG, Switzerland) were collected and analyzed. Cycloplegic refractions were then performed. Overall, 166 eyes of 83 patients diagnosed with NF1 (mean age 21.6 ± 9.8) were enrolled and compared with 178 eyes of age-matched healthy subjects (mean age 22.6 ± 6.6). One hundred sixty-six (22.8%) and 33 of 178 (18.5%) eyes were myopic in NF1 patients and healthy subjects, respectively. The prevalence of hyperopia in the NF1 group was 12 of 166 (7.2%) whereas in the healthy control group was 14 of 178 (8.9%). Twenty-nine of 166 (17.4%) and 34 of 178 (19.1%) eyes presented astigmatism in NF1 and control group, respectively. These differences were not statistically significant (p-values > 0.05). Refractive errors such as myopia, hyperopia, and astigmatism were similar between the two groups. The difference of AL, CCT, ACD, LT, K values, and WTW were no statistically significant between the two groups (p-values > 0.05). Refractive errors and ocular biometric parameter seem not to be an addition findings of NF1.

Peripheral vitreochorioretinal dystrophy in patients with various types of myopia

Background. Over the past decade, there has been an in¬crease in myopia prevalence in the world; in many countries it is considered as epidemic. In case of an unfavorable course, myopia becomes the cause of retinal pathology, which in se¬vere cases leads to an irreversible decrease in corrected visu¬al acuity and to visual impairment that occurs at working age. Purpose. To analyze the relationship between the occurrence of peripheral vitreochorioretinal dystrophy (PVCD) in patients with myopia depending on its type: refractive and axial. Material and methods. A retrospective cohort analysis involved 304 patients (608 eyes) of 13 to 70 years old with acquired myopia: mild (19.40%), moderate (42.93%) and high (37.67%). In all cases, myopia was complicated by PVCD. All patients were divided into 2 groups according to the type of myopia: refractive and axial myopia. Biometric data (LENSTAR LS 900) and keratometry (“Huvitz”, South Korea) were used as criteria for patient selection. Results. The distribution of patients showed that PVCD most often occurs in the group of patients with axial myopia of moderate (44.48%) and high (39.70%) degrees. In the group of patients with mild axial myopia, the incidence was 15.80%. A clear correlation was noted between the development of PVCD and the axial elongation. In contrast, in patients with refractive myopia, the incidence of PVCD was two times higher in case of mild myopia (50.00%) than in cases of moderate (29.69%) and high myopia (20.31%) put together. Conclusion. The study revealed that PVCD is almost 8,5 times more likely to occur in case of axial myopia than in case of refractive myopia. A possible cause of PVCD development in case of axial myopia is an increase in the axial length, while in case of refractive myopia its possible cause is the increase in the eyeball’s transverse size. Regardless of the type of myopia and its degree, the study of the periphery of the retina is an essential element of diagnostics for timely detection of PVCD and monitoring the progression of axial myopia is an important criterion for its prevention.