Normative Pentacam anterior and posterior corneal elevation measurements: effects of age, sex, axial length and white-to-white.

PURPOSE: To provide normal corneal elevation data for a large Caucasian population and to determine the impacts on these data of age, sex, axial length (AXL) and horizontal white-to-white (WW). SETTING: Centro Internacional de Oftalmología Avanzada, Madrid, Spain. DESIGN: Retrospective, cross-sectional, observational. METHODS: In this retrospective, cross-sectional, observational study, anterior and posterior corneal elevations were measured in 789 right eyes of subjects with no ocular disease at the thinnest corneal location in relation to a fixed 8-mm best-fit sphere using the Pentacam, and AXL and WW were measured with the IOLMaster. A multiple linear regression model was used to assess the effects of age, sex, AXL and WW on the elevation data. RESULTS: Mean subject age was 50.5 ± 15 years (range 17-93 years); 64% were women. Mean anterior and posterior corneal elevations were 1.99 ± 1.75 µm (- 7 to 10 µm) and 7.70 ± 5.7 µm (- 6 to 28 µm). Anterior corneal elevations were higher by 0.165 µm and 0.033 µm for every mm reduction in AXL and every year reduction in age, respectively. Sex and WW were not significant predictors of anterior elevations (R2 = 7.7%). Posterior corneal elevation increased by 0.186 µm/year of age, 0.707 µm/mm reduction in WW and 0.819 µm/mm reduction in AXL. This variable was also 0.866 µm greater in men (R2 = 34.4%). CONCLUSION: Anterior corneal elevations decrease with age and are higher for shorter AXL but are not influenced by sex or WW. Posterior corneal elevations increase with age, decreasing AXL, decreasing WW and are higher in men.

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.

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.

Anterior scleral thickness dimensions by swept-source optical coherence tomography.

Clinical relevance: Given the association of scleral characteristics with many ophthalmological diseases, there is an important need to measure the anterior scleral thickness (AST).Background: This study examined the AST by swept-source optical coherence tomography (SS-OCT) in a large healthy population, assessing also the reproducibility of AST measurements and the correlation with different parameters.Methods: Cross-sectional study in 605 eyes of 605 subjects. AST measurements were made in the temporal and nasal quadrants at 1 (AST1) and 3 mm (AST3) from the scleral spur using SS-OCT. These dimensions were then assessed for associations in a multivariate model with the factors age, sex, refractive error, conjunctival-Tenon capsule thickness (CTT), anterior chamber angle (ACA), intraocular pressure (IOP), iris thickness (IT), limbus-sulcus distance (LSD), and ciliary muscle thickness (CMT). The reproducibility of the AST measurements was determined in 30 of the participants.Results: The mean age was 42.6 ± 17.3 years (range 5 to 86 years). The following means were recorded: AST1 was 522.3 ± 65.7 µm (355 to 761) and 558.4 ± 71.5 µm (357 to 889); AST2 was 513.3 ± 67.3 µm (343 to 732) and 574.4 ± 71.6 µm (389 to 789), and AST3 548.8 ± 71.9 µm (356 to 762) and 590.1 ± 76.6 µm (414 to 873) in the temporal and nasal quadrants respectively, being thicker the nasal quadrant (all p < 0.001). A positive correlation was detected between AST and age, sex, temporal ACA and LSD (all p ≤ 0.043), being negative the correlation with CMT (p ≤ 0.044). No correlation was observed between AST measurements and refractive error, CTT and IT (p ≥ 0.064). The reproducibility of AST measurements was excellent (intraclass correlation coefficient ≥0.951).Conclusions: SS-OCT allows for in vivo AST measurements. Our data contained a wide range of measurements, showing an association between AST and age, sex, ACA, LSD and CMT.

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.

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).

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.

Impacts of Implantable Collamer Lens V4c Placement on Angle Measurements Made by Optical Coherence Tomography: Two-Year Follow-up.

PURPOSE: To determine iridocorneal angle changes produced after 2 years of implantable collamer lens (ICL) V4c (STAAR Surgical AG, Nidau, Switzerland) placement by Fourier-domain optical coherence tomography (FD-OCT). DESIGN: Prospective interventional case series. METHODS: In 54 eyes of 27 myopic subjects FD-OCT iridocorneal angle measurements were made before and 1 month, 3 months, 1 year, and 2 years after ICL implant. Trabecular-iris angle (TIA), angle opening distance 500 µm from the scleral spur (AOD500), and iridotrabecular contact length (TICL) were compared among these time points and the nasal, temporal, and inferior quadrants. RESULTS: Preoperative TIAs were 49.5 ± 8.7, 48.3 ± 9.6, and 49.1 ±8.6 degrees for the nasal, temporal and inferior quadrants (P < .001). Corresponding values were 29.9 ± 10.4, 28.4 ± 10.8, and 28.8 ± 9.7 degrees at 1 month and 27.3 ± 8.8, 26.8 ± 8.1, and 28.9 ± 7 degrees at 2 years of follow-up, indicating angle narrowing of 39%-45% and no further narrowing beyond 1 month in the nasal (P = .133), temporal (P = .376), and inferior (P = 1.000) quadrants. Trabecular-iris contact (TIC) was observed in 8 eyes of 8 subjects, mostly only in the temporal quadrant. Mean TICL failed to vary during follow-up (307 ± 288 µm at 3 months and 225 ± 142 µm at 2 years, P = .159). CONCLUSIONS: In response to ICL V4c implant, considerable angle narrowing was detected at 1 month but this narrowing remained stable at 2 years. In the 8 cases of TIC, no progression of contact was observed beyond 3 months postimplant.

Effects of Implantable Collamer Lens V4c Placement on Iridocorneal Angle Measurements by Fourier-Domain Optical Coherence Tomography.

PURPOSE: To assess by Fourier-domain optical coherence tomography (FDOCT) changes produced in iridocorneal angle measurements in patients undergoing Visian Implantable Collamer Lens (ICL) V4c (STAAR Surgical AG) placement. DESIGN: Prospective interventional case series. METHODS: In 50 eyes of 25 myopic subjects consecutively scheduled for ICL implant, FDOCT (RTVue; Optovue Inc) iridocorneal angle measurements were made before and 1 and 3 months after surgery. Trabecular-iris angle (TIA) and angle opening distance 500 µm anterior to the scleral spur (AOD500) were compared among the quadrants nasal, temporal, and inferior, and correlations with ocular variables including lens vault were examined. RESULTS: Preoperative TIA was 48.7 ± 8.7, 48.2 ± 8.7, and 48.7 ± 9.3 degrees for the nasal, temporal, and inferior quadrants, with no differences (P = 1.000). Following ICL implant, corresponding values fell to 31.2 ± 11.5, 30.0 ± 10.7, and 29.7 ± 8.1 degrees at 1 month postsurgery, indicating angle narrowing of 34%-42%, and to 30.6 ± 12.3, 30.1 ± 11.9, and 29.8 ± 12.3 degrees, respectively, at 3 months postsurgery. Angle measurements failed to vary between 1 month and 3 months postsurgery (P = .481). In 8 eyes, iridotrabecular contact attributable to surgery was observed. One month after surgery, vault measurements correlated with TIA (R = -.309; P = .048). Six variables were identified as predictors of TIA at 1 month postsurgery (R(2) = .907). CONCLUSIONS: Although considerable angle narrowing was detected 1 month after ICL V4c implant, this narrowing remained stable at 3 months postsurgery. Factors predictive of TIA could serve to identify suitable candidates for ICL placement.

Determinants of anterior chamber depth in a large Caucasian population and agreement between intra-ocular lens Master and Pentacam measurements of this variable.

PURPOSE: To establish the main determinants of anterior chamber depth (ACD) in Caucasian subjects and examine agreement between IOL Master(®) (Carl Zeiss, Meditec) and Pentacam(®) (Oculus Inc.) ACD measurements. METHODS: In a cross-sectional study, 1006 right eyes of 1006 healthy subjects were subjected to a general ophthalmologic examination using the Pentacam(®) , IOLMaster(®) and OCT RTVue(®) (Optovue Inc.). The variables recorded were age, sex, intra-ocular pressure, spherical refractive error, axial length (AL), central corneal thickness, corneal diameter, iris thickness, and anterior chamber depth, volume and angle (ACA). The effects of these variables on ACD were analysed by multivariate linear regression. RESULTS: Mean age was 49.1 years (range 18-84); 61% were women. In 98.3% of the eyes, ACD could be measured using the IOL Master and in 98% the Pentacam was used to give mean depths of 3.30 ± 0.42 mm and 3.35 ± 0.43 mm, respectively, for the two instruments. Agreement between these devices was high. In men, ACD was 0.13 mm on average deeper than in women (p < 0.001). ACD was correlated with ACA, AL, corneal diameter, spherical refractive error and age (p < 0.001). Five variables - age, sex, spherical error, corneal diameter and ACA - were able to explain 74.1% of the variation produced in ACD (R(2) = 0.741; p < 0.001), among which age emerged as the main determinant (partial R(2) = 0.279; p < 0.001). CONCLUSIONS: Age, sex, spherical error, corneal diameter and ACA correlate highly with ACD and together serve to explain much of its variation. When used to measure ACD, the IOLMaster and Pentacam show excellent agreement.

Computational Study of Aqueous Humor Dynamics Assessing the Vault and the Pupil Diameter in Two Posterior-Chamber Phakic Lenses.

PURPOSE: To compare the behavior of aqueous humor (AH) and analyze flow differences by comparing the volume and velocity of the flow after two different models of implantable collamer lens (ICL) placement. METHODS: Computational fluid dynamics with numerical simulation using Ansys Fluent software was performed to compare the AH flow through a peripheral iridotomy (PI), which is typically performed after implantation of a V4b lens to the central hole of a V4c lens. The volume and flow rate in 24 scenarios were compared according to the type of lens, pupil diameter (PD) (3.5 or 5.5 mm), the vault (100, 350, and 800 µm) and the PI (single or double, 180 or 360 µm). RESULTS: With a standard vault (350 µm) and a PD of 3.5 mm, the volume of AH that flows from the posterior to the anterior chamber through the PI (V4b lens: 73.4% in 360 µm and 17.3% in 180 µm) and for the central hole (V4c lens: 75.7%) is larger than in the case of a PD of 5.5 mm (13.9%, 0.91%, and 15.3% respectively). When the vault is low (100; PD 3.5 mm), the volume of AH that reaches the central hole of the V4c lens is diminished (52.0%), being 5.1% if the pupil is enlarged. CONCLUSIONS: AH flow varies depending on the type of ICL implanted, whether it is implanted with an iridotomy or a central hole on the lens, the PD, and the vault.