Refractive outcomes comparison between the Lenstar LS 900® optical biometry and immersion A-scan ultrasound

Parallel comparison of ocular metrics in non-human primates with high myopia by LS900, ultrasonography and MRI-based 3D reconstruction

We investigate the ocular dimensions and shape by using Lenstar900 (LS900), A-scan ultrasonography, and Magnetic Resonance Imaging (MRI) in highly myopic Macaca fascicularis. The ocular dimensions data of LS900, A-scan ultrasonography and MRI was assessed from 8 eyes (4 adult male cynomolgus macaque) with extremely high myopia (≤-1000DS) and compared by means of coefficients of concordance and 95% limits of agreement. Multiple regression analysis was performed to explore the associations between ocular biometry, volume, refraction and inter-instrument discrepancies. Test-retest reliability of three measurements of ocular parameters at two time points was almost equal (intraclass correlation = 0.831 to 1.000). The parallel-forms reliability of three measurements was strong for vitreous chamber depth (VCD) (coefficient of concordance = 0.919 to 0.981), moderate for axial length (AL) (coefficient of concordance = 0.486 to 0.981), and weak for anterior chamber depth (ACD) (coefficient of concordance = 0.267 to 0.621) and lens thickness (LT) (coefficient of concordance = 0.035 to 0.631). The LS900 and MRI systematically underestimated the ACD and LT comparing to A-scan ultrasonography (P < 0.05). Notably, the average AL on LS900 displayed a significant correlation with those on MRI (r = 0.978, P < 0.001) and A-scan ultrasonography (r = 0.990, P < 0.001). Almost 4/5 eyeballs were prolate. The mean eyeball volume positively correlated with AL (r = 0.782, P = 0.022), the width (r = 0.945, P = 0.000), and the length (r = 0.782, P = 0.022) of eyeball, while negatively correlated with SER (r = -0.901, P = 0.000). In conclusion, there was a high inter-instrument concordance for VCD with LS900, A-scan ultrasonography and MRI, while ACD and LT were underestimated with LS900 compared to A-scan ultrasonography, and the LS900 and A-scan ultrasonography could reliably measure the AL. MRI further revealed an equatorial globe shape in extremely myopic non-human primates.

Long-term longitudinal changes in axial length in the Caucasian myopic and hyperopic population with a phakic intraocular lens

Purpose

To determine the long‐term longitudinal axial length changes in myopic and hyperopic adults with an iris‐fixated phakic intraocular lens (pIOL).

Methods

The medical records of patients aged ≥18 years with myopia or hyperopia who were treated with pIOL implantation between 1996 and 2011 for refractive correction with a minimum follow‐up of 5 years after pIOL implantation were analyzed. The main outcome measure was change in ocular axial length over time.

Results

149 eyes of 149 myopic patients and 27 hyperopic eyes of 27 patients were included in this study. Mean patient age was 37.1 ± 10.4 years (35% male) in the myopic group and 39.4 ± 9.4 years (4% male) in the hyperopic group. The eyes of the myopic patients showed a significant mean increase in axial length of 0.45 ± 0.61 mm after a mean follow‐up time of 144 ± 38 months (p < 0.001). In 26 eyes (17%), the axial length had increased by ≥1 mm. The mean annual axial length increase was 0.04 ± 0.06 mm. Axial elongation was associated with a higher degree of myopia (p < 0.001) and younger age (p = 0.02). The eyes of the hyperopic patients showed no change in axial length over time.

Conclusions

Myopic eyes corrected with an iris‐fixated pIOL show continuous increase in axial length at an adult age. Although this study is limited to subjects with a pIOL, this is the first time myopization in Caucasian adults has been reported in a large long‐term longitudinal study.

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.

Estimation of angle kappa and pupil barycentre configuration in myopic tilted disc syndrome

BACKGROUND

To evaluate the angle kappa and pupil barycentre configuration in patients with myopic tilted disc syndrome (TDS).

METHODS

Thirty-five eyes of 35 patients with TDS were included in the study. Thirty-five eyes of 35 age- and sex-matched healthy subjects were enrolled in the control group. All measurements were performed with the Lenstar LS 900. Angle kappa was calculated according to Pythagorean theorem using the x and y co-ordinates of the pupil centre. Pupil dx and pupil dy values (pupil dx: x co-ordinate of pupil centre relative to corneal apex, pupil dy: y co-ordinate of pupil centre relative to corneal apex) were used to evaluate the pupil barycentre configuration. Central corneal thickness, white to white (cornea diameter), pupil diameter, anterior chamber depth, lens thickness, and axial length were also measured.

RESULTS

The calculated mean angle kappa distance was 0.27 ± 0.15 mm in the TDS group and 0.29 ± 0.23 mm in the control group (p = 0.42). The mean pupil dx was -0.01 ± 0.24 mm in the TDS group and -0.17 ± 0.14 mm in the control group (p = 0.006). The mean pupil dy was -0.02 ± 0.13 mm in the TDS group and -0.05 ± 0.22 mm in the control group (p = 0.65).

CONCLUSIONS

The pupil barycentre in TDS cases was statistically significantly closer to the corneal vertex on the horizontal plane compared to the control group. However, there was no statistically significant differences in terms of angle kappa and pupil dy values between the groups. According to our results, refractive surgery can be performed safely with respect to complications related to decentration of ablation zone and decentration of multifocal intraocular lenses in these groups of patients.

Comparison of a new image-guided system versus partial coherence interferometry, Scheimpflug imaging, and optical low-coherence reflectometry devices: Keratometry and repeatability

PURPOSE

To determine the repeatability of keratometry of the Verion image-guided system and to compare the keratometry (K) values with those of established biometric devices.

SETTING

International Vision Correction Research Centre, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany.

DESIGN

Prospective case series.

METHODS

One randomly chosen eye of volunteers was examined with partial coherence interferometry (PCI) (IOLMaster 500), optical low-coherence reflectometry (OLCR) (Lenstar LS 900), a Scheimpflug device (Pentacam HR), and the new image-guided system by the same examiner. None of the eyes had ocular pathology. Three consecutive measurements were performed with the image-guided system and 1 with the other devices. The flat, steep, and average corneal radii; steep axis; and white-to-white (WTW) distance were analyzed and compared.

RESULTS

One hundred twenty-three eyes of 123 volunteers (mean age 37.9 years ± 16.2 [SD]) had valid measurements for all examinations and were available for analysis. The image-guided system measured statistically significant smaller flat, steep, and average corneal radii than the Scheimpflug device, statistically significant larger flat and average corneal radii than the PCI device, and no statistically significant different values than the OLCR device. The measured steep axis did not differ significantly in any comparison. The WTW measurements were significantly higher than those of all other devices. The analysis of repeatability of the image-guided system showed high intraclass correlation coefficients (range 0.919 to 0.997).

CONCLUSIONS

The new image-guided system had high repeatability for K, steep axis, and WTW measurements. The WTW measurements with the image-guided system were significantly higher than those using the other devices.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

Comparision of Optical Low Coherence Reflectometry Versus Ultrasonic Biometry in High Hypermetropia

PURPOSE

To compare anterior chamber depth (ACD), axial length (AL), and lens thickness (LT) measurements obtained by the Lenstar LS 900 (Haag-Streit AG) optical low-coherence reflectometry with those obtained by the A-scan contact ultrasound among patients with moderate and high hypermetropia.

METHODS

Fifty-two eyes of 52 patients with moderate and high hypermetropia (spherical equivalent of +4 D or more) were examined in this study measurements of ACD, AL, and LT obtained by Lenstar were compared with those obtained by applanation A-scan ultrasound. All measurements were obtained by two independent examiners. The interdevice agreements were evaluated with Bland-Altman analyses.

RESULTS

The mean age of the patients was 54.78±12.77 years (range 18-74 years). The mean spherical equivalent refractive power was +5.16±1.12 D (+4.0 to +8.75). The mean values of ACD, AL, and LT with A-scan were 3.05±0.34, 21.55±0.75, and 4.33±0.49 mm, respectively, whereas these values were 2.99±0.45, 21.58±0.78, and 4.20±0.44 mm, respectively, with Lenstar. There was statistically significant difference of LT between the two methods (P=0.02). The mean differences (lower/upper limit of agreement) of the ACD, AL, and LT values for A-scan ultrasound and Lenstar were -0.06 (-0.594/0.474), 0.04 (-0.380/0.459), and -0.12 (-0.739/0.502), respectively.

CONCLUSION

Among patients with moderate and high hypermetropia, the biometric measurements of ACD, AL, and LT by ultrasound and optical biometry were determined to be correlated and there was a high degree of agreement between contact A-scan ultrasonic biometry and Lenstar.