Publications
The work behind the tools. Peer-reviewed papers and conference presentations from members of the group, across myopia, posterior chamber phakic lenses and anterior-segment image analysis.
2026
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Myopia Peer-reviewed
Influence of Cycloplegia on Axial Length Prediction Models in a Paediatric Sample
Ophthalmic and Physiological Optics 46(3) · May 2026 · doi:10.1007/s44402-026-00095-3 (opens in a new tab)
Abstract
Accurate axial length (AL) estimation is vital for monitoring myopia progression in children, especially in primary care where optical biometers are often unavailable. Prediction models with cycloplegic measurements may offer a reliable alternative. To assess the effect of cycloplegia on the accuracy and repeatability of several AL prediction models in a paediatric sample and to identify which models maintain minimal bias under both cycloplegic and non-cycloplegic conditions.
Ninety-six children (mean age 12.5 ± 2.4 years) underwent repeated measurements of spherical equivalent refraction (SER), anterior corneal curvature (Kmean) and AL, pre- and post-cycloplegia, using the Myopia Master. Seven published prediction models incorporating SER, Kmean, age and sex were evaluated. Agreement, bias, limits of agreement (LoA), coefficient of repeatability (CoR), intraclass correlation coefficient (ICC) and regression analyses were used to assess performance and repeatability.
Cycloplegia induced a hyperopic shift (mean +0.79 D), most pronounced in emmetropic and hyperopic eyes. Measured AL and all models showed improved repeatability post-cycloplegia (measured AL CoR decreased from ~0.14 mm to ~0.09 mm; ICC > 0.99). Pre-cycloplegia, models overestimated AL (mean differences from −0.87 to −0.24 mm); these biases were reduced post-cycloplegia (mean differences from −0.56 to +0.10 mm). Models by Morgan et al., Queirós et al. and Lingham had the smallest bias (<0.10 mm) and narrowest LoA (<0.84 mm). Variation in SER accounted for ~97–99% of the change in predicted AL, while Kmean contributed ≤1.2%.
Cycloplegic refraction significantly enhanced both accuracy and repeatability of AL prediction models in children. Models by Morgan et al., Queirós et al. and Lingham et al. performed best. Predictive models may be a valuable substitute in settings without access to optical biometers, provided cycloplegic measurements are used when possible.
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Image analysis Conference
Anterior segment optical coherence tomography image spatial features in the retro-iris space
AOP 2026, Lisbon, 7–10 July 2026 · doi:10.34629/ipl.isel.i-ETC.108 (opens in a new tab)
Abstract
Purpose. Anterior segment optical coherence tomography (AS-OCT) cannot reliably image the retro-iris space, where a dominant non-anatomical signal overlaps weaker retro-iris backscatter. This study assessed whether local statistical descriptors could distinguish these contributions and identify a candidate anatomical signal.
Methods. Seventy-four swept-source AS-OCT B-scans were analysed, 50 for signal characterisation and 24 for biometric validation. Local entropy, standard deviation (STD) and range were computed using circular kernels. Kernel radius was selected from the Kullback–Leibler divergence between probability density functions at consecutive radii. Gaussian mixture models identified candidate anatomical components, which were restricted to a one-standard-deviation interval, intersected and spatially filtered.
Results. A 30-pixel radius (75 µm) was selected for all three metrics. The models resolved four, two and three components for entropy, STD and range, respectively. The selected intervals retained 68–71% of each candidate component with less than 5% contamination. The candidate-region centroid distance correlated with scleral-spur distance and lay anterior to the crystalline lens equator.
Conclusions. Local statistical descriptors identified a spatially localised retro-iris signal consistent with the ciliary process region, supporting further evaluation of non-invasive posterior-chamber assessment.
Earlier
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Posterior chamber phakic lenses Peer-reviewed
Influence of anterior chamber depth and vault on anterior chamber angle morphology after phakic posterior chamber intraocular lens implantation
International Ophthalmology 44(1):14 · February 2024 · doi:10.1007/s10792-024-02924-1 (opens in a new tab)
Abstract
Purpose. This study aims to investigate the influence of anterior chamber depth (ACD) and vault on the anterior chamber angle (ACA) morphology in myopic individuals implanted with posterior chamber phakic intraocular lenses.
Methods. This retrospective case series involved 231 eyes receiving a 13.2-mm implantable collamer lens (ICL). Preoperative anterior chamber anatomy was assessed using anterior segment optical coherence tomography (AS-OCT) and optical tomography, while postoperative evaluation employed AS-OCT. ACA morphology was characterized pre- and postoperatively through trabecular iris angle (TIA750), ACA distance opening (AOD750) and trabecular iris space area (TISA750). The influence of ACD and vault was examined by categorizing the sample into ACD (shallow, average and deep) and vault (low, optimal and high) groups.
Results. Preoperative ACA morphology varied based on ACD, with shallower ACDs exhibiting narrower TIA750, smaller AOD750 and TISA750. ICL implantation induced greater ACA narrowing more in the deep ACD group (TIA750 = 20.1 degrees; AOD750 = 0.82 mm and TISA750 = 0.44 mm²) compared to the shallow ACD group (TIA750 = 15.2 degrees; AOD750 = 0.44 mm and TISA750 = 0.21 mm²). Postoperatively, deeper ACDs showed larger ACAs. Increasing vault magnitude led to increased ACA narrowing, with the low vault group exhibiting smaller closure (TIA750 = 14.3 degrees; AOD750 = 0.56 mm and TISA750 = 0.29 mm²) compared to the high vault group (TIA750 = 20.8 degrees; AOD750 = 0.73 mm and TISA750 = 0.36 mm²). The magnitude of ACA narrowing associated with the vault had a consistent effect across different ACD groups.
Conclusions. Posterior chamber intraocular lens implantation results in ACA narrowing, the extent of which is contingent upon preoperative anterior chamber and ACA morphology, with additional influence from vault magnitude.
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Posterior chamber phakic lenses Conference
Agreement between predicted and real vault measured in eyes implanted with implantable collamer lens, using AS-OCT based formulas
ESCRS Winter Meeting 2023 · March 2023 · doi:10.13140/RG.2.2.21869.14564 (opens in a new tab)
Abstract
This study evaluated the predictive performance of two preoperative ICL vault prediction formulas (ST-formula and KS-formula) in 209 eyes implanted with EVO-V4c ICLs. Preoperative AS-OCT biometric parameters were compared with postoperative vault measurements obtained three months after surgery. Both formulas showed a tendency to overestimate vault values, with the ST-formula demonstrating slightly better agreement with measured vaults. Approximately 60% of predictions were within 250 µm of the actual vault, although both formulas showed limited precision in predicting exact vault values and failed to accurately identify extremely low vaults. Nevertheless, the formulas proved useful for the preoperative detection of eyes at risk of high postoperative vaults.
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Posterior chamber phakic lenses Conference
Phakic lens vault measured using the SS-OCT based biometer IOLMASTER-700
ESCRS Winter Meeting 2023, Algarve · March 2023 · doi:10.13140/RG.2.2.18513.70245 (opens in a new tab)
Abstract
This study evaluated the agreement between vault measurements obtained with the AS-OCT Visante and the SS-OCT biometer IOLMaster 700 in eyes implanted with EVO-V4c ICLs. Twenty-four eyes were assessed one month postoperatively. The IOLMaster 700 provided superior visualization of the ICL contours and faster image acquisition compared to the Visante. Mean vault measurements were slightly lower with the IOLMaster 700, although both devices showed excellent correlation (R²=0.98). Despite the high agreement, the instruments should not be considered interchangeable due to systematic differences in measurements. The rapid acquisition of multiple meridians with the IOLMaster 700 may also improve the assessment of ICL tilt and decentration.
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Posterior chamber phakic lenses Peer-reviewed
Prediction model of the horizontal trabecular iris angle after phakic posterior chamber implantable intraocular lens surgery
Journal of Cataract and Refractive Surgery · February 2023 · doi:10.1097/j.jcrs.0000000000001171 (opens in a new tab)
Abstract
Purpose. To determine the predictors of the postoperative horizontal trabecular iris angle (TIA750) after phakic posterior chamber implantable intraocular lens (IOL) surgery. Setting. Ophthalmology Clinic Vista Sánchez Trancón. Design. Retrospective case series.
Methods. This study included 330 eyes implanted with spherical/toric Implantable Collamer Lens (ICL). From 230 eyes implanted with 13.2 mm ICL, these were divided in modelling (n=180) and evaluation group (n=50). Two groups implanted with 12.6 and 13.7 mm (n=50 each) were also used as evaluation. Anterior-segment OCT was used preoperatively to perform anterior chamber biometry (angle-to-angle distance (ATA), crystalline lens rise (CLR), anterior chamber depth (ACD), cornea sagittal depth, pupil diameter, nasal/temporal TIA750); postoperatively for measuring the vault, pupil diameter and nasal/temporal TIA750. Corneal curvature and horizontal visible iris diameter were measured using optical tomography.
Results. Horizontal TIA750 reduced from 42.9±8.0 degrees preoperatively to 24.4±5.6 degrees postoperatively. Postoperative TIA750 was positively correlated with the preoperative TIA750, cornea sagittal depth and ACD, and negatively associated with the vault. The main predictors of the postoperative TIA750 were the preoperative parameters, TIA750, ICLsize − ATA and pupil diameter (adjusted-R²=0.39). The limits of agreement between predicted and real TIA750 were close to ±10 degrees.
Conclusions. Implantation of a phakic posterior chamber implantable IOL leads to a reduction in TIA750 and the main factors contributing for this are the preoperative TIA750 aperture and the vault.
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Posterior chamber phakic lenses Peer-reviewed
Vault differences in eyes implanted with spherical and toric implantable collamer lenses: an inter-eye analysis
BMC Ophthalmology 22(1):435 · November 2022 · doi:10.1186/s12886-022-02653-y (opens in a new tab)
Abstract
Purpose. To determine the influence of implantable collamer lenses (ICL) geometry, i.e. spherical and toric on the vault, and report the refractive and visual outcomes of patients bilaterally implanted with the two ICL geometries.
Methods. This retrospective case series analysed 41 patients implanted with a spherical ICL (sICL) in one eye and an equal sized toric ICL (tICL) in the fellow eye. The anatomical and ICL-related parameters were assessed using anterior-segment optical coherence tomography (AS-OCT Visante, Zeiss Meditec AG) and optical tomography (Pentacam, OCULUS). The influence of the anatomical and ICL-related parameters on the vault was determined using generalised estimating equations (GEE) to incorporate inter-eye correlations.
Results. Postoperative spherical equivalent was within ±0.50 D in 66% and 83% of the eyes, respectively implanted with sICL and tICL. The efficacy index in the sICL group was 1.06 and 1.14 in the tICL group. The mean inter-eye vault difference was −1.46 µm; anatomical and ICL-related parameters showed similar associations with the vault for sICL and tICL. The GEE identified the ICL size minus the anterior chamber width, the ICL spherical power and ICL central thickness as significant factors influencing the vault.
Conclusions. Spherical and toric ICL showed good efficacy for the correction of myopia and astigmatism. Patients implanted bilaterally with sICL and tICL tend to present similar vaults. The vault produced by both types of ICL was mainly regulated by the oversizing of the ICL. This suggests that the ICL geometry (spherical vs toric) is a factor with limited influence on the vault, thus the sizing method of a sICL and tICL should be similar.
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Posterior chamber phakic lenses Peer-reviewed
Posterior Chamber Phakic Intraocular Lenses for the Correction of Myopia: Factors Influencing the Postoperative Refraction
Optics 2(4):292–305 · December 2021 · doi:10.3390/opt2040028 (opens in a new tab)
Abstract
Posterior chamber phakic intraocular lens implantation is a refractive technique for the correction of myopia. This study aimed to identify those factors contributing to variability in postoperative refraction.
Methods. This retrospective study evaluated 73 eyes (one eye per patient) implanted with myopic implantable collamer lenses (ICL). Eyes were divided into two groups, the low myopic group (LMG) (ICL > −9.5 DS) and the high myopic group (HMG) (ICL ≤ −9.5 DS), to compare the predictability, efficacy index, and postoperative refraction between groups. The association of postoperative refraction with anatomical, demographic, and optical features was assessed through correlation analysis and investigated using ray-tracing.
Results. Postoperative refraction at 3 months for the whole group was close to emmetropia at −0.02 ± 0.37 DS; the LMG tended toward myopia and the HMG toward hyperopia. The results showed that 65% and 54% of the eyes had postoperative refraction of within ±0.25 DS, respectively, in the LMG and HMG, and in both groups, 100% were within ±1.00 DS. ICL implantation had a higher efficacy index in the HMG (1.13 ± 0.15) than in the LMG (1.04 ± 0.15). Postoperative refraction was positively associated with the vault (R = 0.408) and negatively correlated with ICL power (R = −0.382).
Conclusion. The predictability and effectiveness of ICL implantation is high in a wide range of myopias. Considering the expected vault and including accurate vertex measurements would contribute to improving the predictability of the results.
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Posterior chamber phakic lenses Peer-reviewed
Biometric and ICL-related risk factors associated to sub-optimal vaults in eyes implanted with implantable collamer lenses
Eye and Vision 8(1) · July 2021 · doi:10.1186/s40662-021-00250-6 (opens in a new tab)
Abstract
Background. To identify biometric and implantable collamer lens (ICL)-related risk factors associated with sub-optimal postoperative vault in eyes implanted with phakic ICL.
Methods. This study reports a retrospective case series of the first operated eye in 360 patients implanted with myopic spherical or toric ICL. Preoperatively, white-to-white (WTW), central keratometry (Kc) and central corneal thickness (CCT) were measured using the Pentacam. Anterior-segment optical coherence tomography (AS-OCT, Visante) was applied preoperatively for measuring the horizontal anterior-chamber angle-to-angle distance (ATA), internal anterior chamber depth (ACD), crystalline lens rise (CLR), anterior-chamber angle (ACA) and postoperatively the vault. Eyes were divided into three vault groups: low (LVG: ≤ 250 µm), optimal (OVG: > 250 and < 1000 µm) and high (HVG: ≥ 1000 µm). Multinomial logistic regression (MLR) was used to find the sub-optimal vault predictors.
Results. MLR showed that CLR, ICL size minus the ATA (ICL size−ATA), age, ICL spherical equivalent (ICLSE) and ICL size as contributing factors for sub-optimal vaults (pseudo-R² = 0.40). Increased CLR (OR: 1.01, CI: 1.00–1.01) and less myopic ICLSE (OR: 1.22, CI: 1.07–1.40) were risk factors for low vaults. Larger ICL size−ATA (OR: 41.29, CI: 10.57–161.22) and the 13.7 mm ICL (OR: 7.08, CI: 3.16–15.89) were risk factors for high vaults, whereas less myopic ICLSE (OR: 0.85, CI: 0.76–0.95) and older age (OR: 0.92, CI: 0.88–0.98) were protective factors.
Conclusion. High CLR and low ICLSE were the major risk factors in eyes presenting low vaults. In the opposite direction, ICL size−ATA was the major contributor for high vaults. This relationship was more critical in higher myopic ICLSE, younger eyes and when 13.7 mm ICL were used. The findings show that factors influencing the vault have differentiated weight of influence depending on the type of vault (low, optimal or high).
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Posterior chamber phakic lenses Peer-reviewed
Inter-Eye Vault Differences of Implantable Collamer Lens Measured Using Anterior Segment Optical Coherence Tomography
Clinical Ophthalmology 14:3563 · October 2020 · doi:10.2147/OPTH.S258817 (opens in a new tab)
Abstract
Purpose. The distance between an implantable collamer lens (ICL) and the crystalline lens, namely vault, is a space regulated by the interaction of the ICL and the anatomical structures of the eye. This study analysed the differences in vault size between fellow eyes with similar anterior segment biometry.
Patients and Methods. A retrospective case series analysed 109 cases of patients bilaterally implanted with EVO-V4c. Patients were analysed pre- and postoperatively using anterior segment optical coherence tomography. The range of vault inter-eye differences was defined as the 95% confidence interval of the differences. Bivariate correlation was applied to seek for associations between vault inter-eye differences with biometric and lens parameters.
Results. Mean vault inter-eye differences were similar between fellow eyes (26.0 ± 122.5 µm). The 95% confidence interval range of the differences was ±240.1 µm; nearly 50% of the cases presented vault inter-eye differences higher than 100 µm. The vault of the first operated eye explained 81% of the variance in the second eye vault. Vault inter-eye differences were positively correlated with the level of horizontal compression and with vault magnitude.
Conclusion. Vaults measured in fellow eyes may present considerable differences, which can reach 25% of the common vault range. This reflects some degree of baseline variability in the vault. Clinically, these differences assume special relevance in cases where low or high vaults are expected.
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Posterior chamber phakic lenses Peer-reviewed
Determining vault size in Implantable Collamer Lenses (ICL): preoperative anatomy and lens parameters
Journal of Cataract and Refractive Surgery 46(5) · January 2020 · doi:10.1097/j.jcrs.0000000000000146 (opens in a new tab)
Abstract
Purpose. This study aims to determine the patients’ preoperative anatomical features and ICL parameters relevant in explaining the vault variability. Setting. Ophthalmology Clinic Vista Sánchez Trancón, Badajoz, Spain. Design. Retrospective case series.
Methods. This study comprises 360 eyes (1 eye–1 patient) implanted with myopic or toric ICL. Pentacam imaging was used for assessing white-to-white (WTW), central keratometry (Kc) and central corneal thickness (CCT). Anterior-segment optical coherence tomography (AS-OCT) Visante was applied for measuring the horizontal anterior chamber angle distance (ATA), internal anterior chamber (ACQ), crystalline lens rise (CLR), anterior chamber angle (ACA) and vault. The sample was divided according to the implanted lens (12.6, 13.2 and 13.7 mm). Vault predictors were identified from the variables above using multivariate regression analysis.
Results. The groups showed significant statistical differences for WTW, ATA, ACQ, ACA and vault (p<0.007 for all). In general, bigger lenses were implanted in eyes with larger transverse sizes (WTW and ATA) and deeper ACQ. Also, larger ICL diameters were associated with higher vaults. Multivariate regression analysis identified the lens size (13.2 mm as reference; 12.6 mm: β = −0.33; 13.7 mm: β = 0.42), ATA (β = −0.42), CLR (β = −0.25), ICL spherical equivalent (β = −0.22) and patients’ age (β = −0.12) as predictors of the vault size (adjusted-R = 0.34, p<0.001).
Conclusions. The multivariate model explained 34% of the vault’s variability. The predictors indicate the presence of different mechanisms regulating the vault. These involve the difference between the transverse size of the eye and the ICL, the crystalline lens protrusion and the ICL properties such as power and size.
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Most of the questions this group cares about need more eyes than any one clinic sees. If you have a dataset, a study in progress, or a result that doesn’t match the literature, that’s the conversation we want.