Comparative study of the glistening between four intraocular lens models assessed by OCT and deep learning.

PURPOSE: To evaluate the glistening in 4 different models of intraocular lenses (IOLs) using optical coherence tomography (OCT) and deep learning (DL). SETTING: Centro Internacional de Oftalmología Avanzada (Madrid, Spain). DESIGN: Cross-sectional study. METHODS: 325 eyes were assessed for the presence and severity of glistening in 4 IOL models: ReSTOR+3 SN6AD1 (n = 41), SN60WF (n = 110), PanOptix TFNT (n = 128) and Vivity DFT015 (n = 46). The presence of glistening was analyzed using OCT, identifying the presence of hyperreflective foci (HRF) in the central area of the IOL. A manual and an original DL-based quantification algorithm designed for this purpose was applied. RESULTS: Glistening was detected in 22 (53.7%) ReSTOR SN6AD1, 44 (40%) SN60WF, 49 (38.3%) PanOptix TFNT, and 4 (8.7%) Vivity DFT015 IOLs, when any grade was considered. In the comparison of the different types of IOLs, global glistening measured as total HRF was 17.3 ± 25.9 for the ReSTOR+3; 9.3 ± 15.7 for the SN60WF; 6.9 ± 10.5 for the PanOptix; and 1.2 ± 2.6 for the Vivity ( P < .05). There was excellent agreement between manual and DL-based quantification (≥0.829). CONCLUSIONS: It is possible to quantify, classify and compare the glistening severity in different IOL models using OCT images in a simple and objective manner with a DL algorithm. In the comparative study, the Vivity presented the lowest severity of glistening.

Comparison in conjunctival-Tenon's capsule thickness, anterior scleral thickness and ciliary muscle dimensions between Caucasians and Hispanic by optical coherence tomography.

PURPOSE: To investigate the differences in the dimensions of the anterior ocular segment, and specifically in conjunctival-Tenon's capsule thickness (CTT), anterior scleral thickness (AST) and ciliary muscle thickness (CMT), between Caucasian and Hispanic subjects using swept-source optical coherence tomography (SS-OCT). METHODS: Cross-sectional study including 53 Hispanic and 60 Caucasian healthy participants, matched by age, sex and refractive error, who underwent a complete ophthalmological examination. CTT, AST and CMT were manually measured in the temporal and nasal quadrants at 0, 1, 2 and 3 mm from the scleral spur using SS-OCT. RESULTS: Mean age and refractive error were 38.7 ± 12.3 years and -1.05 ± 2.6 diopters, and 41.8 ± 11.7 years and -0.50 ± 2.6 diopters for the Hispanic and Caucasians, respectively (p = 0.165 and p = 0.244). The CTT was increased in the temporal quadrant in the Hispanic group in the three studied regions (CTT1, CTT2 and CTT3; being the means 223.0 ± 68.4, 215.3 ± 66.4 and 203.8 ± 67.1 µm versus 190.8 ± 51.0, 189.4 ± 53.2 and 187.4 ± 55.3 µm respectively; p < 0.001). Larger AST values were observed in the temporal quadrant in the Hispanic group (AST2: 559.8 ± 80.8 µm and AST3: 591.6 ± 83.0 µm) compared to the Caucasian group (520.7 ± 50.1 and 558.9 ± 54.7 respectively; p ≤ 0.022). No differences were observed in the nasal quadrant for CTT, AST1 and AST3 (p ≥ 0.076). No differences emerged in the CM dimensions (p ≥ 0.055). CONCLUSION: CTT and AST measurements were thicker in the temporal quadrant of Hispanic patients compared to Caucasians. This could have implications for the pathogenesis of different ocular diseases.

Normative Topographic Anterior and Posterior Corneal Astigmatism: Axis Distribution and Its Relations with Ocular and Biometric Parameters.

Corneal astigmatism correction is a key factor when planning refractive treatment for ametropies with intraocular lenses. We aim to obtain normative anterior and posterior corneal astigmatism (ACA and PCA, respectively) data in a local population and to describe their axis distribution and their association with other parameters. A total of 795 patients with no ocular diseases were evaluated with corneal tomography and optical biometry. Only data of the right eye were included. Mean ACA and PCA were 1.01 ± 0.79 and 0.34 ± 0.17 D, respectively. Vertical steep axis distribution was 73.5% for ACA and 93.3% for PCA. Axis orientation between ACA and PCA matched best for vertical orientation (especially 90° to 120°). Vertical ACA orientation frequency decreased with age, with a more positive sphere and less ACA. Vertical PCA orientation frequency increased with higher PCA. Eyes with vertical ACA orientation were younger and showed a greater white-to-white (WTW) measurement, anterior corneal elevations, ACA and PCA. Eyes with vertical PCA orientation were younger and showed greater anterior corneal elevations and PCA. Normative ACA and PCA data in a Spanish population were presented. Steep axis orientations presented differences with age, WTW, anterior corneal elevations and astigmatism.

Reply to Stanojcic et al. Comment on "Fernández-Vigo et al. Objective Classification of Glistening in Implanted Intraocular Lenses Using Optical Coherence Tomography: Proposal for a New Classification and Grading System. J. Clin. Med. 2023, 12, 2351".

We appreciate the comments made by Stanojcic et al. [...].

Objective Classification of Glistening in Implanted Intraocular Lenses Using Optical Coherence Tomography: Proposal for a New Classification and Grading System.

PURPOSE: To propose a classification of the glistening in intraocular lenses (IOL) using swept-source optical coherence tomography (SS-OCT) by means of a simple, objective and reproducible method that allows the quantification of the presence and severity of glistening. METHODS: A cross-sectional study on a sample of 150 eyes of 150 patients who underwent cataract surgery in at least 600 days before the exam and attended a routine examination. Each subject was examined by SS-OCT after pupil dilation, identifying the presence of glistening or hyperreflective foci (HRF) in the central area of the IOL. The degree of glistening was classified into four categories: 0: ≤5 HRF; 1: 6 to 15 HRF; 2: 16 to 30 HRF; and 3: >30 HRF. The intra and interobserver reproducibility (intraclass correlation coefficient, ICC) in the quantification and classification of the glistening were calculated. The correlation between the horizontal and vertical scan of the IOL was also assessed. RESULTS: Glistening was present in the IOL in 42.7% of the patients. The mean number of HRF or glistening microvacuoles was 10.4 ± 26.2 (range 0 to 239). In total, 63.3% of the IOLs had a grade 0, 20% grade a 1, 6.7% grade a 2 and 10% a grade 3. The intraobserver and interobserver reproducibility were very high, both for the absolute quantification of the glistening (ICC ≥ 0.994) and for the severity scale (ICC ≥ 0.967). There was an excellent correlation in the quantification of the IOL glistening between the horizontal and vertical scans (R ≥ 0.834; p < 0.001). CONCLUSIONS: The use of SS-OCT makes it possible to identify, quantify and classify IOL glistening in a simple, objective and reproducible way. This technique could provide relevant information for the study of the glistening on IOLs.

Association between macular and papillary vessel density by optical coherence tomography angiography in a large healthy population.

PURPOSE: To provide a normative data set of the relationship between macular and papillary vessel density (VD) using swept-source optical coherence tomography angiography (SS-OCTA) in a large healthy population. METHODS: Cross-sectional study conducted on 346 right eyes of healthy subjects. Macular and papillary SS-OCTA VD measurements of the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) in the central area and the four quadrants were obtained. Correlations between macular and papillary VD among different quadrants were assessed. RESULTS: The mean participant age was 37.7 ± 19.8 years (range 5-83); 59% were women. No correlation was detected neither for the global SCP (R = 0.050; P = 0.040), DCP (R = -0.056; P = 0.038) nor CC (R = 0.102; P < 0.001) between macular and papillary VD. In a subanalysis, there was also no correlation in any of the quadrants studied (R ≤ 0.180; P < 0.001). In a subgroup of 45 left eyes, there was no correlation in the different plexus and layers studied between macular and papillary vasculature. No differences in SCP, DCP and CC were found according to gender, age or axial length in the relationship between macular and papillary VD. CONCLUSION: There is no association between macular and papillary VD neither in the SCP, DCP or CC in any of the regions studied. Hence, macular and optic nerve head vascularization should be investigated separately to identify which structure is more relevant in each disease.

Updates on the utility of anterior segment optical coherence tomography in the assessment of filtration blebs after glaucoma surgery.

The formation of filtration blebs is the main drainage mechanism for reducing intraocular pressure after traditional incisional glaucoma surgery such as trabeculectomy and non-penetrating deep sclerotomy. Early and short-lasting blebs may also occur after canaloplasty. Bleb formation also plays an important role after the implantation of glaucoma drainage devices, including Minimally Invasive Glaucoma Surgery devices. Anterior segment optical coherence tomography (AS-OCT) is a rapid and non-invasive high-resolution imaging technique that has evolved in recent years to become a routine examination. Anterior segment optical coherence tomography (AS-OCT) provides key information in the assessment and follow-up of glaucoma surgery, especially in the assessment of filtration blebs. Thus, bleb morphology can be qualitatively classified into diffuse, cystic, encapsulated and flattened, and AS-OCT imaging can also provide several quantitative parameters of the bleb, such as total bleb height, bleb fluid-filled cavity height, bleb wall thickness, number of microcysts and trabeculectomy opening size. These parameters could have an impact on clinical management during follow-up because they may predict the success or failure of the surgery in the early and late postoperative periods. Additionally, they may also guide the procedures used to increase filtration and reduce intraocular pressure, such as bleb needling and laser suture lysis.

Diagnostic imaging of the ciliary body: Technologies, outcomes, and future perspectives.

The ciliary body (CB) is part of the uvea and is a complex, highly specialized structure with multiple functions and significant relationships with nearby structures. Its functions include the aqueous humor (AH) production in the ciliary processes, the regulation of the AH output through the uveoscleral pathway, and accommodation, which depends on the ciliary muscle. Also, the CB is an important determinant of angle width as it forms part of the ciliary sulcus. Until recently, knowledge of the CB was based on histological studies. However, this structure can currently be assessed in vivo using imaging techniques such as ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT). Both techniques have shown good reproducibility of their measurements allowing for quantification of CB dimensions and their localization. In effect, studies have shown a larger CB in myopia and its diminishing size with age. Swept-source OCT devices offer fast, non-invasive high-resolution imaging allowing the identification of multiple structures. UBM requires contact and is uncomfortable for the patient. However, this technique offers deeper imaging and therefore remains the gold standard for assessing the posterior chamber, ciliary processes, or zonula. The clinical utility of CB imaging includes its assessment in different types of glaucoma such as angle-closure, malignant or plateau iris. Diagnostic CB imaging is also invaluable for the assessment of ciliochoroidal detachment when suspected, the position after the implantation of a pre-crystalline or sulcus-sutured lenses, diagnosis or monitoring of cysts or tumors, sclerotomies after retinal surgery, intermediate uveitis, or accommodation.

Dimensions of the limbus-ciliary sulcus region by OCT and correlation study in a large population.

PURPOSE: To assess the dimensions of the limbus-ciliary sulcus region measured by swept-source optical coherence tomography (SS-OCT) and conduct a correlation study in a large healthy population. SETTING: Centro Internacional de Oftalmología Avanzada, Madrid, Spain. DESIGN: Cross-sectional study. METHODS: The dimensions of the limbus-ciliary sulcus region were measured in the temporal and nasal quadrants using a SS-OCT. The limbus-sulcus distance (LSD), the posterior iris line-ocular surface to limbus distance (PIOLD), and the angle-to-sulcus distance (ASD) were measured. These distances were then assessed for correlations with factors such as age, sex, refractive error, anterior chamber angle (ACA), ciliary muscle thickness (CMT), conjunctival-Tenon capsule thickness (CTT), and anterior scleral thickness (AST). RESULTS: The mean age of the participants was 41.0 ± 18.2 years (range 5 to 86) and the mean refractive error -0.75 ± 3.3 diopters (range -10 to 7). The LSD could be measured in 93.2% of the participants (625 eyes out of 670 eyes), with a mean of 1.35 ± 0.12 mm (range 0.96 to 1.75) and 1.33 ± 0.12 mm (range 1.05 to 1.68) in the temporal and nasal quadrants, respectively, and a correlation of R = 0.616 (P < .001) between them. PIOLD measured 2.22 ± 0.31 mm (1.42 to 2.98), and ASD was 0.21 ± 0.05 mm (0.01 to 0.40). No correlation was observed between LSD with age, spherical error, sex, or ACA (P ≥ .247). However, LSD exhibited the highest correlation with AST (R = 0.466), followed by CTT (R = 0.309) and CMT (R = 0.259). CONCLUSIONS: The SS-OCT allowed for an accurate in vivo measurement of the dimensions of the limbus-ciliary sulcus region.

Impact of age, sex and refractive error on conjunctival and Tenon's capsule thickness dimensions by swept-source optical coherence tomography in a large population.

PURPOSE: To evaluate conjunctival and Tenon's capsule thickness (CTT) in a large healthy population using swept-source optical coherence tomography (SS-OCT), investigating the impact of age, sex and refractive error. METHODS: 630 healthy participants underwent a complete ophthalmological examination. CTT was manually measured in the temporal and nasal quadrants at 0, 1, 2 and 3 mm from the scleral spur using SS-OCT (CTT0, CTT1, CTT2 and CTT3, respectively). These dimensions were then assessed for associations in a multivariate regression model with age, sex, refractive error and anterior scleral thickness (AST). The reproducibility of the CTT measurements was determined in 30 individuals. RESULTS: CTT dimensions could be measured in 596 cases (94.6%); mean age was 42.6 ± 17.2 years (range 5-86). Mean CTT0 was 199.2 ± 33.8 and 192.9 ± 33.9 µm, mean CTT1 195.4 ± 38.0 µm and 199.9 ± 50.9 µm, mean CTT2 187.0 ± 38.4 and 194.8 ± 48.9 µm, and CTT3 180.5 ± 35.6 µm and 191.8 ± 43.7 µm, for the temporal and nasal quadrants, respectively. No difference in CTT was observed in the nasal versus temporal quadrant (p ≥ 0.106) except for the CTT0 and CTT3 (p = 0.001). Moderate correlation was observed between nasal and temporal CTT (R = 0.472, p < 0.001). In the multivariate model, no influence was observed by sex, refractive error and AST on CTT measurements (p ≥ 0.065). Negative association was observed between age and CTT (p < 0.005). The reproducibility was excellent (intraclass correlation coefficient ≥ 0.908). CONCLUSIONS: SS-OCT allows for in vivo CTT evaluation. Our data document a wide range of measurements, showing negative association between CTT and age.

Numerical model to predict and compare the hypotensive efficacy and safety of minimally invasive glaucoma surgery devices.

PURPOSE: To predict and compare the hypotensive efficacy of three minimally-invasive glaucoma surgery (MIGS) implants through a numerical model. METHODS: Post-implant hypotensive efficacy was evaluated by using a numerical model and a computational fluid dynamics simulation. Three different devices were compared: the XEN 45 stent (tube diameter, 45 µm), the XEN 63 stent (63 µm) and the PreserFlo microshunt (70 µm). The influence of the filtration bleb pressure (Bp) and tube diameter, length, and position within the anterior chamber (AC) on intraocular pressure (IOP) were evaluated. RESULTS: Using baseline IOPs of 25, 30 and 50 mmHg, respectively, the corresponding computed post-implant IOPs for each device were as follows: XEN 45: 17 mmHg (29% decrease), 19 mmHg (45%) and 20 mmHg (59%) respectively; XEN 63: 13 mmHg (48%), 13 mmHg (62%), and 13 mmHg (73%); PreserFlo: 12 mmHg (59%), 13 mmHg (73%) and 13 mmHg (73%). At a baseline IOP of 35 mmHg with an increase in the outflow resistance within the Bp from 5 to 17 mmHg, the hypotensive efficacy for each device was reduced as follows: XEN45: 54% to 37%; XEN 63: 74% to 46%; and PreserFlo: 75% to 47%. The length and the position of the tube in the AC had only a minimal (non-significant) effect on IOP (<0.1 mmHg). CONCLUSIONS: This hydrodynamic/numerical model showed that implant diameter and bleb pressure are the two most pertinent determinants of hypotensive efficacy. In distinction, tube length and position in the AC do not significantly influence IOP.

Ciliary muscle dimensions measured by swept-source optical coherence tomography in eyes with primary open-angle glaucoma and healthy eyes.

PURPOSE: To compare in vivo swept-source optical coherence tomography (SS-OCT) measurements of the ciliary muscle (CM) in patients with primary open-angle glaucoma (POAG) and healthy subjects, and examine correlations between CM dimensions and several covariates. METHODS: This was a cross-sectional study of the right eyes of 181 subjects: 89 POAG patients and 92 healthy subjects. Using the Triton SS-OCT device (Topcon, Tokyo, Japan), CM length (CML), area (CMA) and thickness measured 1000 µm (CMT1), 2000 µm (CMT2) and 3000 µm (CMT3) from the scleral spur were determined in the temporal and nasal quadrants. POAG patients were subjected to visual field (VF) and peripapillary retinal nerve fiber layer (RNFL) assessment. CM dimensions were then assessed for correlation with VF mean defect (MD), mean RNFL thickness and intraocular pressure (IOP). RESULTS: Mean CMLs were 4325 ± 340 µm and 4195 ± 843 µm for the healthy subjects and POAG patients, respectively (p = 0.17). Mean CM thicknesses were CMT1 = 546 ± 56 µm, CMT2 = 326 ± 44 µm and CMT3 = 174 ± 16 µm in the healthy eyes versus CMT1 = 534 ± 108, CMT2 = 332 ± 99 and CMT3 = 183 ± 74 in the POAG eyes, with no significant differences detected (all p ≥ 0.25). In the temporal quadrant, mean CMA was 1.12 ± 0.29 mm2 and 1.15 ± 0.24 mm2 for the healthy and POAG subjects, respectively (p = 0.45). No correlations were observed between CM measurements and RNFL thickness (p ≥ 0.15), IOP or VF MD (p ≥ 0.14) in POAG subjects irrespective of glaucoma severity (p ≥ 0.19). CONCLUSIONS: While SS-OCT proved useful to measure CM dimensions in vivo, these dimensions did not differ between healthy individuals and POAG subjects. In the patients with POAG, no correlations were detected between CM dimensions and VF, RNFL or IOP.

Normative Database of Peripapillary Vessel Density Measured by Optical Coherence Tomography Angiography and Correlation Study.

Purpose: To provide a normative data set of swept-source optical coherence tomography angiography (SS-OCTA) peripapillary vessel density (VD) measurements and assess correlations with age, gender, disc area and axial length (AL). Material and Methods: This was an observational cross-sectional study conducted on 346 right eyes of healthy subjects. Peripapillary SS-OCTA VD measurements were obtained in the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) in all four quadrants using the Triton device (Topcon, Nagoya, Japan). AL measurements were made by optical biometry. Results: Mean participant age was 37.7 ± 19.8 years (range 5- 83), AL was 23.9 ± 1.3 mm (21-27), and 59% were women. Mean VDs for all quadrants were 57.2 ± 5.7% for SCP (52.4 ± 4.0% - 62.1 ± 4.2%), 46.3 ± 6.5% for DCP (41.9 ± 5.8% - 49.7 ± 4.8%) and 60.8 ± 7.4% for CC (53.4 ± 5.8% - 65.7 ± 5.5%). Negative correlation was detected between SCP VD and age (R = -0.264; P < .001), while correlation between DCP densities and age was positive (R = 0.202; P = .002). No associations were detected between peripapillary VD and gender (P ≥ 0.087) and negative correlation was found with AL and disc area only in the CC (P ≤ 0.004). In a subgroup analysis of 33 individuals, we noted no differences in VD between fellow eyes (P ≥ 0.139). Conclusion: Peripapillary VD showed wide individual variation when measured with the Triton SS-OCTA in the different retinal plexuses and CC. While correlations were observed with age, no relationships emerged with gender and only CC showed negative correlation with AL and disc area.

Reproducibility of macular and optic nerve head vessel density measurements by swept-source optical coherence tomography angiography.

PURPOSE: To assess the reproducibility of swept-source optical coherence tomography angiography (SS-OCTA) for macular and optic nerve head (ONH) vessel density (VD). METHODS: Cross-sectional study using the Triton OCTA (Topcon, Tokyo, Japan), for VD (%) measurements in 40 eyes of 40 healthy subjects on two 6 × 6 mm scans of the macula and ONH across five subfields (central, superior, inferior, temporal, and nasal) at different segmentation levels: superficial capillary plexus (SCP), deep capillary plexus (DCP), outer retina, and choriocapillaris. Reproducibility values were summarized as intraclass correlation coefficients (ICCs) and coefficients of variations (CV). RESULTS: ICCs for the macular VD measurements in the central zone were 0.874, 0.770, 0.575, 0.718 at the levels SCP, DCP, outer retina, and choriocapillaris, respectively, while worse ICCs were obtained for the parafoveal subfields (ICC ⩽ 0.589); CVs were 2.8%-6.7%. The reproducibility of the ONH superficial VD was ICC = 0.941 for the papillary region and was ICC = 0.499-0.853 for the peripapillary zone; CVs ranged from 4.8% to 17%. Peripapillary VD showed an ICC = 0.533-0.770 in the DCP layer, and 0.572-0.828 in the choriocapillaris. Lowest VD were obtained for the macular SCP and DCP (23% and 22%, respectively), in the foveal zone, while greatest VD were recorded in the nasal and temporal peripapillary subfields at the level of the choriocapillaris (both 68%). CONCLUSIONS: The new SS-OCTA software served to quantify macular and ONH VD with a reproducibility that was good in the central zones (foveal and papillary, respectively) and moderate in the peripheral zones (parafoveal and peripapillary).

Ciliary muscle dimensions by swept-source optical coherence tomography and correlation study in a large population.

PURPOSE: To examine ciliary muscle (CM) dimensions in vivo by swept-source optical coherence tomography (SS-OCT) in a large healthy population. To assess the reproducibility of CM measurements and correlations with different parameters. METHODS: In this cross-sectional study, the following CM measurements were made in 495 eyes of 495 subjects in the temporal and nasal quadrants: length (CML), area (CMA) and thickness at distances of 1000 µm (CMT1), 2000 µm (CMT2) and 3000 µm (CMT3) from the scleral spur using the SS-OCT DRI-Triton® (Topcon, Tokyo, Japan). These dimensions were then assessed for correlations with the factors age, gender, refractive error, anterior chamber angle (ACA) and intraocular pressure (IOP). The reproducibility of CM measurements was determined in 85 of the participants. RESULTS: Mean age was 41.4 ± 17.5 years (range 5-83). The following means were recorded as follows: CML = 4.57 ± 0.73 mm (range 2.16-6.97), CMA = 1.35 ± 0.31 mm2 (2.04-5.45), CMT1 = 558 ± 98 µm (299-891), CMT2 = 366 ± 100 µm (89-629) and CMT3 = 210 ± 75 µm (36-655). Negative correlation was detected between CML/CMA and age (R = -0.516/R = -0.404; p < 0.001) and refractive error (R = -0.519/R = -0.538; p < 0.001). No gender differences were observed (p ≥ 0.150). Both CML and CMA were correlated with ACA (R = 0.498 and 0.546; p < 0.001) and slightly with IOP (R = -0.175; p < 0.001). The reproducibility of the CM measurements was excellent (intraclass correlation coefficient ≥0.878). CONCLUSIONS: Swept-source optical coherence tomography is a valid tool for in vivo CM measurements. Our data indicate a larger CM in myopes and its diminishing size with age.

Schlemm's canal measured by optical coherence tomography and correlation study in a healthy Caucasian child population.

PURPOSE: To measure the Schlemm's canal (SC) in vivo by Fourier-domain optical coherence tomography (FD-OCT) in a Caucasian paediatric population. METHODS: Participants of this cross-sectional study were 290 healthy children. In the right eye of each child, SC cross-sectional diameter and area measurements were made with the FD-OCT instrument RTVue® (Optovue Inc, Fremont, CA, USA) in the nasal and temporal quadrants. These SC variables were then assessed for correlation with the factors age, gender, refractive error, anterior chamber angle and trabecular meshwork (TM) metrics. Finally, the reproducibility of the SC measurements was assessed in 30 of the participants. RESULTS: Mean participant age was 10.7 ± 3.4 years (range 3-18). SC diameters could be measured in both quadrants in 70.6% and 70.4% of subjects, respectively. Mean SC diameters were similar (p = 0.125) for the temporal and nasal quadrants: 266.7 ± 84.1 µm (range 131-509) and 273.2 ± 77.3 µm (range 124-486), respectively. Mean SC areas were also similar (p = 0.167) for the two quadrants: 9975 ± 3514 µm2 (range 4000-23 000) versus 9688 ± 3297 µm2 (range 3000-24 000). No differences were detected in SC measurements according to gender, refractive error or angle and TM measurements (R ≤ 0.116; p ≥ 0.125). The exception was age which was directly correlated with SC size (p ≤ 0.041). The reproducibility of the SC measurements was excellent (intraclass correlation coefficients ≥0.936). CONCLUSION: FD-OCT allows the identification of the SC in children. Our data indicate an increase in SC size produced with age.

Computational simulation of aqueous humour dynamics in the presence of a posterior-chamber versus iris-fixed phakic intraocular lens.

PURPOSE: To compare aqueous humour (AH) dynamics in the presence of a precrystalline (Implantable Collamer Lens®; ICL) or iris-fixed (Artiflex®) phakic intraocular lens (PIOL). METHODS: By computational fluid dynamics simulation, AH flow was modelled through a peripheral iridotomy (PI) or central lens hole (both 360 µm) in the presence of an Artiflex or ICL lens, respectively. The impacts of AH flow were then determined in terms of wall shear stress (WSS) produced on the endothelium or crystalline lens. Effects were also modelled for different scenarios of pupil diameter (PD 3.5 or 5.5 mm), ICL vault (100, 350, 800 µm) and number of Artiflex iridotomies (1 or 2) and location (12 or 6 o'clock). RESULTS: For a PD of 3.5 mm, AH volumes flowing from the posterior to the anterior chamber were 37.6% of total flow through the lens hole (ICL) and 84.2% through PI (Artiflex). For an enlarged PD (5.5 mm), corresponding values were 10.3% and 81.9% respectively, so PI constitutes a very efficient way of evacuating AH. Central endothelial WSS in Pa was lower for the large vault ICL and the Artiflex (1-03 and 1.1-03 respectively) compared to the PIOL-free eye (1.6-03). Crystalline lens WSS was highest for the lowest vault ICL (1-04). CONCLUSIONS: AH flow varied according to the presence of a precrystalline or iris-fixed intraocular lens. Endothelial WSS was lower for an implanted ICL with large vault and Artiflex than in the PIOL-free eye, while highest crystalline WSS was recorded for the lowest vault ICL.