Optimization of implantable collamer lens sizing based on swept-source anterior segment optical coherence tomography.

To derive and validate a novel vault prediction formula to improve the predictability and safety of implantable collamer lens (ICL) implantation. Thirty-five patients (61 eyes) with previous posterior chamber intraocular lens implantation were included. Various parameters, such as horizontal-visible iris diameter (HVID), photopic pupil diameter (PPD), axial length (AL), white-to-white (WTW), anterior chamber width (ACW), angle-to-angle (ATA), crystalline lens rise (CLR), anterior chamber depth (ACD), horizontal sulcus-to-sulcus (HSTS), and ciliary sulcus angle (CSA) were measured. Vault was measured at 3 months after surgery using CASIA2 anterior segment optical coherence tomography. The formula was derived using multiple linear regression analysis and named as WH formula. It was validated in 65 patients (118 eyes) to determine the percentage of the ideal postoperative vault range and to compare the differences between the WH formula and the NK, KS, and STAAR formulas. Final ICL size, ATA, CSA, and CLR were included in the prediction formula model (adjusted R2 = 0.67, p < 0.001). The achieved vault 1 month after the surgery was 556.19 μm ± 166.98 μm in the validation group, and the ideal vault range was 200-800 μm (92%). The difference between the achieved vault and that predicted using the WH formula was not statistically significant (p = 0.165), whereas the difference between the achieved vault and that predicted using the NK and KS formulas was statistically significant (p < 0.001 and p < 0.001, respectively). The 95% agreement limit range of the achieved vault and the vault predicted using the WH formula was narrower than those predicted using the NK and KS formulas (-295.20-258.82 μm). This study combined the results of optical coherence tomography and ultrasound biomicroscopy measurements of the anterior segment of the eye and incorporated ciliary sulcus morphology quantification into the prediction formula. The study derived a prediction formula for vault by combining ICL size, ATA, and CLR. The derived formula was found to be superior to the currently available formulas.

To develop regression formulas for determining optimal Implantable Collamer Lens (ICL) size based on AnterionAS-OCT (anterior segment optical coherence tomography) biometric data. In this retrospective interventional case series, 89 patients were included in the development phase and 57 patients were included in the (internal) validation phase. The study developed the SN (Salouti-Nowroozzadeh) formula, a multiple step-wise linear regression model, incorporating anterior chamber width (ACW), lens thickness, and anterior chamber volume (ACV) as predictors, to determine optimal ICL size (R-square=0.602). Another formula predicted ICL vault using a cubic non-linear model and the difference (Delta) between implanted and predicted ICL size as an explanatory variable (R-square = 0.599). Logistic regression determined the probability of achieving optimal vault or acceptable vault post-surgery. We also present findings from 73 consecutive prospective cases from a separate dataset, where the ICL was determined using the SN formula (external validation). Delta was the sole independent factor predicting postoperative ICL vault. A ∆ value of 0.3 mm corresponded to a 65% probability of achieving optimal vault, while a ∆ value of 0.15 resulted in an 80% probability. The SN formula matched with the STAAR nomogram in 69.9% of cases (79/113). Compared to the STAAR formula, the SN formula recommended a larger size in 10 eyes (8.8%) and a smaller size in 24 (21.2%). The 95% LoA for SN-predicted and actual ICL vault were (-339 to 518) µm. The mean absolute error was 191 µm (SD,139), and 72 eyes (63.7%) had a difference of ≤200 µm. The external validation analysis confirmed the primary findings. The developed regression formula provided acceptable predictions for proper ICL sizing in our patients. However, its performance may vary across different populations or measurement devices. This study also highlights the need for smaller increments of ICL sizes to improve postoperative outcomes with any given formula.

Aims/Purpose: To develop a method for measuring the exact dimensions of the ciliary sulcus in order to improve the predictability of accommodative intraocular lens sizing.Methods: Patients scheduled for cataract surgery have been pre‐operatively examined with the anterior segment optical coherence tomographer (AS‐OCT) CASIA2 (Tomey, Nagoya, Japan). Optimized scan protocols were defined to improve the image quality of the ciliary structures. The horizontal scan from 0° to 180° was taken to represent the space where a sulcus‐fixated accommodative intraocular lens (IOL), whose diameter must agree with that of the ciliary sulcus, may be placed. The images were corrected for the optical distortion induced by the cornea's refraction. The sulcus‐to‐sulcus (STS) size as well as the depth of the sulcus plane (SPD) was measured using the integrated software calliper by two independent raters. Inter‐rater variability and correlation were evaluated. In addition, STS measurements were compared to other ocular diameter measures, such as angle‐to‐angle (ATA) and anterior chamber width (ACW). Data were analysed by means of correlation coefficient R2 and Bland–Altmann analysis.Results: 55 eyes of 28 patients were included in the study. The optimized scan protocols improved overall image quality and subjective visibility of ciliary anatomy compared to the default protocol. STS ranged from 10.66 mm to 12.89 mm, ACW from 10.76 mm to 12.74 mm and ATA from 10.69 to 12.46 mm. SPD ranged from 3.73 mm to 5.0 mm, while ATA depth was between 2.74 mm and 3.95 mm. Readings of both raters were highly correlated (R2 &gt; 0.98). Manual readings of STS correlated poorly with automated ACW and ATA measurements (R2 &lt; 0.66). The mean difference was 0.018 mm for STS and −0.011 mm for SPD. The levels of agreement were within [−0.109; +0.145] mm for STS and [−0.112; +0.091] mm for SPD.Conclusions: Despite the absorption of light by the iris pigment, the infrared light from the AS‐OCT is able to penetrate the posterior chamber to some degree. Therefore, the new AS‐OCT method for sulcus‐to‐sulcus and ciliary dimensions measurements seems to be feasible, reliable and is less bothersome for the patients compared to ultrasound bio‐microscopy. This approach could be useful for sulcus fixated accommodative IOLs and for sizing determination of posterior chamber phakic IOLs.

Anterior segment optical coherence tomography in black‐on‐clear polypseudophakia

As a result of the insufficient ocular anatomical parameters used to customize implantable collamer lens (ICL), many patients still cannot achieve a suitable vault after ICL implantation surgery. This study analyzed the characteristics of a new anatomical parameter crystalline lens rise (CLR) in a population with high myopia and explored the influence of CLR on the vault after ICL implantation. Patients (298 eyes) with high myopia who underwent ICL implantation were enrolled to study CLR characteristics. Postoperatively, patients (159 eyes) were divided into five groups according to the value of CLR (A, CLR ≤ - 150; B, - 150 < CLR ≤ 0; C, 0 < CLR < 150; D, 150 ≤ CLR < 300; E, CLR ≥ 300μm), and to investigate the correlation between CLR and vault. In the 298 eyes, the CLR had a normal distribution (P = 0.35) and the mean CLR was 67.93 ± 150.66μm. Ninety-nine eyes (33.22%) had a CLR ≤ 0μm, of which 20 eyes (6.71%) had a CLR ≤ - 150μm; 199 eyes (66.78%) had a CLR > 0μm, of which 20 eyes (6.71%) had a CLR ≥ 300μm. In 159 eyes, the CLR was negatively correlated with the vault at 1day (R = - 0.497, P < 0.001), 3months (R = - 0.505, P < 0.001), and 6months (R = - 0.505, P < 0.001) postoperatively. At 6months, the vault of groupA was statistically significantly different compared to groups B-E (all P < 0.05), and that of groupE was statistically significantly different compared to groupsA-D (all P < 0.001). The remaining groups did not show statistically significant differences (all P > 0.05). The CLR had a normal distribution in the high myopia population, and 13.42% of the CLR values were extreme (CLR ≤ - 150μm or CLR ≥ 300μm). A larger ICL diameter than that recommended by the manufacturer should be considered when the CLR is ≥ 300μm and a smaller ICL diameter should be considered when the CLR is ≤ - 150μm.

Objective To measure quantitatively and analysis the differences in the anterior segment biological parameters between the normal subject and patients suffering primary angle closure glaucoma (PACG), as well as the distinction among different stages of PACG by using anterior segment optical coherence tomography (OCT). Methods A retrospective case series study was designed.Medical records of 217 cases (217 eyes) from The Second Hospital of Hebei Medical University from December 2013 to December 2014 were recruited, including 5 groups as follows: 35 cases (35 eyes) with pre-clinical stage acute primary angle closure glaucoma (APACG), 32 cases (32 eyes) with remission period of APACG, 35 cases (35 eyes) with early stage of chronic primary angle closure glaucoma (CPACG), 35 cases (35 eyes) with progress period of CPACG and 80 cases (80 eyes) coming for regular eye health examination in general clinic.The anterior segment biological parameters of each group was measured by Heidelberg Spectralis OCT, including the anterior chamber width (ACW), angle opening distance (AOD), trabecular iris area (TISA), iris thickness (IT) and crystalline lens rise (CLR). Results The IT and CLR of APACG and CPACG were significantly greater than normal control group, while other anterior segment parameters were significantly smaller, with significant differences between them (all at P 0.05). Compared with progress period of CPACG, the IT of the early stage of CPACG was thicker, while the CLR was smaller (both at P 0.05). The IT750, IT2 000 and ITmax of the pre-clinical stage of APACG were significantly thicker than those of progress period of CPACG (all at P 0.05). Conclusions Compared with normal people, the PACG patients have a more crowding anterior segment structure, smaller AOD, smaller TISA, thicker IT and more anterior located lens.The APACG patient at remission period has a more crowding anterior segment structure, smaller AOD, smaller TISA, thicker IT and more anterior located lens than APACG patient at per-clinic stage.The CPACG patient at progress period has a higher CLR, but thinner IT than patient at early stage.The APACG patients at per-clinic stage has thicker IT and a more crowding anterior segment structure than the CPACG patient at early stage, and the APACG patient at remission period has thicker IT than CPACG patient at progress period. Key words: Angle-closure glaucoma; Anterior segment; Optical coherence tomography; Anterior segment biological parameters

To quantify the effect of the significant ocular bio-parameters and the nomograms for an optimal Implantable Collamer Lens (ICL) vault. Regional eye hospital. Retrospective. Consecutive 103 patients (200 eyes) with implantation of ICL V4c were analyzed to find the important anterior eye parameters and the nomograms to achieve the optimal vaults (250 to 750 µm). The study found that anterior chamber width (ACW, β = 5.17, p = 0.0003), angle-to-angle (ATA, β = -3.1, p = 0.0084), and crystalline lens rise (β = 0.0044, p = 0.0007) are the significant parameters for predicting optimal vaults. For the ACW, a 10 µm increase from its mean (11.76 mm) would lead to 1.76 times higher odds for an optimized vault while holding all other variables constant. In contrast, a 100 µm increase from the ATA mean (11.63 mm) was associated with a 9.5% reduction in odds to achieve an optimal vault. CASIA2-NK or the Dougherty nomogram had similar higher odds to achieve an optimal vault than that by OCOS (odds ratio = 5.8, p = 0.0069; odds ratio = 3.3, p = 0.024). The magnitude of the difference between ACW and ATA was significantly associated with the odds of optimal vault. The ACW and the ATA are both significant predictors for achieving an optimal vault; their size difference may bear significant value for ICL optimal vaults. CASIA2, along with its integrated formula, may be a stand-alone handy option for ICL size selection for the East Asian population.

Repeatability and reproducibility of anterior ocular biometric measurements with 2-dimensional and 3-dimensional optical coherence tomography

Swept-source anterior segment optical coherence tomography in late-onset capsular block syndrome: High-resolution imaging and morphometric modifications after posterior capsulotomy

The determination of sulcus-to-sulcus measurements has been challenging due to the limitations of current approaches. Ultrasound methods are highly operator-dependent and require extensive training, while traditional optical devices cannot visualize structures posterior to the iris. However, modern optical anterior segment coherence tomography (AS-OCT) devices are changing this paradigm by identifying some anatomical landmarks posterior to the iris. This study evaluates the reproducibility of optical sulcus measurements in the context of sizing a novel accommodative intraocular lens (IOL). Preoperative OCT scans of patients scheduled for cataract surgery were analyzed regarding the dimensions of the ciliary sulcus using a custom scan method with a clinically available anterior segment optical coherence tomographer. Measurements were compared between two different readers, and various derived parameters were compared. The measurements by both readers were highly correlated (R2 > 0.96), and their agreement was excellent (mean difference 0.02 mm with 95% limits of agreement from -0.11 to 0.15 mm). In contrast, the sulcus diameter measurement did not agree well with automatically calculated values, such as the anterior chamber width or white-to-white. This leads to the conclusion that modern swept-source AS-OCT measurements of the ciliary sulcus dimensions are feasible, reproducible, and may be a clinically useful tool.

To quantitatively assess intraocular lens (IOL) calcification using anterior segment optical coherence tomography (AS-OCT) and correlate findings with straylight measurements in patients with homogenous IOL calcification. Department of Ophthalmology, Heidelberg University Hospital, Heidelberg, Germany. Prospective, observational clinical study. Healthy patients with homogenous IOL calcification underwent AS-OCT imaging with the ANTERION, with IOL opacity being automatically quantified using a custom image-analysis script. Straylight was assessed using the C-Quant straylight meter. Correlation between IOL opacity and straylight was analyzed using Spearman ρ coefficient. 35 eyes of 35 patients (mean age 72.9 ± 7.8 years) were included. Mean IOL opacity was 69.15 ± 13.55 pixel intensity units (PIUs), and mean straylight was 2.24 ± 0.38 log(s). A statistically significant correlation was found between IOL opacity and straylight with ρ = 0.494, P = .003. After the linear regression model was established: straylight = 0.0569 × OCT opacity [log(s)] - 1.69 with R2 = 0.244. Of the 35 eyes, 17 underwent IOL exchange surgery, with a mean IOL opacity of 75.69 ± 7.58 PIU and a mean straylight of 2.33 ± 0.30 log(s). AS-OCT can quantitatively assess IOL calcification in vivo, with results correlating significantly with straylight measurements. This technique may serve as a valuable diagnostic tool for evaluating IOL opacification and assist in surgical decision-making, particularly in borderline cases.

To evaluate the application of anterior segment-optical coherence tomography (AS-OCT) in posterior capsule opacification (PCO) severity assessment and analyse the relationship between PCO severity and intraocular lens (IOL) characters. PCO patients were prospectively recruited. Cross-sectional images of the anterior segment at horizontal and vertical meridians were acquired with AS-OCT. The area of the IOL-PC (posterior capsular) space and PCO severity (area, thickness, and density at 3 mm and 5 mm IOL optic regions) were measured. The relationship between PCO severity and visual acuity, comparisons of PCO severity and IOL-PC space using varied IOL designs were analysed. One hundred PCO eyes were enrolled. IOL-PC space, PCO thickness and area were positively correlated with axial length. In addition, PCO area and thickness were positively correlated with visual acuity when it was ≤0.52 logMAR. The cut-off level of visual acuity should be 0.52 logMAR. With varied IOL designs, 3-piece C haptic IOL showed a smaller PCO area and thickness than the 1-piece 3 haptic IOL and 1-piece 4 haptic IOL. PCO area and thickness values for an IOL with a diameter ≤11.0 mm was greater than for an IOL with a diameter of 12.5 mm, and the differences were statistically significant. PCO area and thickness increased when IOL haptic angulation increased (from 0 to 12 degrees). In PCO eyes, cut-off level of visual acuity is 0.52 logMAR. With more severe PCO, visual acuity maybe not enough to describe the visual function impairment. PCO severity and IOL-PC space are significantly correlated with axial length and IOL design and material.

Postoperative opacification of a hydrophilic acrylic intraocular lens (IOL) is an uncommon complication. A 57-year-old diabetic female who had undergone phacoemulsification with IOL implantation in her right eye 16 years back presented with diminution of vision in the same eye for 3 years. Significant IOL opacification was observed clinically and anterior segment optical coherence tomography clearly delineated the intraoptic deposits, sparing the haptics, and edges of the optic. IOL explant and exchange was performed leading to restoration of visual acuity to 6/9. Histochemical evaluation of the IOL confirmed that the hydrophilic acrylic IOL optic had calcium deposits.

Purpose: To provide a mathematical calculation scheme for customized intraocular lens (IOL) design based on high resolution anterior segment optical coherence tomography (AS-OCT) of anterior eye segment and axial length data.Material and Methods: We use the corneal and anterior segment data from the high resolution AS-OCT and the axial length data from the IOLMaster to create a pseudophakic eye model. An inverse calculation algorithm for the IOL back surface optimization is introduced. We employ free form surface representation (bi-cubic spline) for the corneal and IOL surface. The merit of this strategy is demonstrated by comparing with a standard spherical model and quadratic function. Four models are calculated: (1) quadratic cornea + quadratic IOL; (2) spline cornea + quadratic IOL; (3) spline cornea + spline IOL; and (4) spherical cornea + spherical IOL. The IOL optimization process for the pseudophakic eye is performed by numerical ray-tracing method within a 6-mm zone. The spot diagram on the fovea (forward ray-tracing) and wavefront at the spectacle plane (backward ray-tracing) are compared for different models respectively.Results: The models with quadratic (1) or spline (3) surface representation showed superior image performance than the spherical model 4. The residual wavefront errors (peak to valley) of models 1, 2, and 3 are below one micron scale. Model 4 showed max wavefront error of about 15 µm peak to valley. However, the combination of quadratic best fit IOL with the free form cornea (model 2) showed one magnitude smaller wavefront error than the spherical representation of both surfaces (model 3). This results from higher order terms in cornea height profile.Conclusions: A four-surface eye model using a numerical ray-tracing method is proposed for customized IOL calculation. High resolution OCT data can be used as a sufficient base for a customized IOL characterization.

To establish a novel vault prediction formula after implantable collamer lens (ICL) implantation that considers both anterior and posterior chamber characteristics with multi-modal parameters. A total of 103 and 65 eyes were included in the development and validation groups, respectively. Exploratory factor analysis was performed using data from optical coherence tomography and ultrasound biomicroscopy in the development group to synthesise summative factors with different clinical significance. Dominant original metrics with heavy loadings on significant factors (absolute value of the loading coefficient >0.5) were screened for multivariate linear regression models using a stepwise method. The newly derived formula was evaluated and compared to the NK and KS formulas in the validation group. Six factors (anterior chamber angle, horizontal width, lens, iris, iridociliary complex and ciliary body) were generated after dimension reduction via factor analysis. Factors 2 (horizontal width), 3 (lens), and 5 (iridociliary complex) had a significant influence on the vault. When dominant metrics on these factors were screened for further model building, ICL size, anterior chamber width, crystalline lens rise, iris curvature, and iris-ciliary process distance were retained in the final formula, with an adjusted R2 of 0.698, a median absolute error of 81.97 mm, and a root-mean-square error of 103.35 mm. Multiple intraocular components, including the lens, iris, and ciliary body, play important roles in vault determination. The new formula exhibits good accuracy for vault predictions and ICL size recommendations.