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

Ocular biometrics in eyes with different white-to-white corneal diameter in young myopic adults

The interactions between white-to-white corneal diameter (WTW) and other ocular biometrics are important for planning of refractive surgery and understanding of ocular structural changes in myopia, but such interactions are rarely investigated in young myopic adults. This is a retrospective study involving 7893 young myopic adults from five centers. WTW and other ocular biometrics were measured by Pentacam. The ocular biometrics included anterior corneal curvature (AK) and posterior corneal curvature (PK), central corneal thickness (CCT) and corneal volume (CV), anterior and corneal eccentricity and asphericity, anterior corneal astigmatism (ACA) and posterior corneal astigmatism, anterior chamber depth (ACD), and anterior chamber volume (ACV). The ocular biometrics were compared among eyes of different WTW quartiles. Multivariate linear regression was used to assess the linear associations between WTW and other ocular biometrics adjusting for age, gender and spherical equivalent. In eyes of different WTW quartiles, other ocular biometrics were also significantly different (all P < 0.05). After adjusting for age, gender and spherical equivalent, WTW was positively correlated to AK (β = 0.26 to 0.29), ACA (β = 0.13), anterior corneal asphericity (β = 0.05), PK (β = 0.33 to 0.34), posterior corneal asphericity (β = 0.13), ACD (β = 0.29), and ACV (β = 40.69), and was negatively correlated to CCT (β = - 6.83), CV (β = - 0.06 to - 0.78), anterior corneal eccentricity (β = - 0.035), and posterior corneal eccentricity (β = - 0.14) (all P < 0.001). In conclusion, we found that in young myopic adults, larger WTW was associated with thinner corneal thickness, flatter corneal curvature, more anterior corneal toricity, less corneal eccentricity and asphericity, and broader anterior chamber. Our findings may fill in the gap of literature, and help us better understand how the anterior segment structures interact with the WTW in myopia.

Correlation of Ocular Biometry with Axial Length in Elderly Japanese

Purpose

Ocular parameters are not only useful for diagnosing diseases but also for guiding treatment approaches. A lot of previous studies have reported ocular parameters and its relations before cataract surgery. However, despite ethnic differences in ocular biometry, few reports have dealt with Japanese. Hence, this retrospective cross-sectional study aimed to measure parameters of preoperative cataract patients and examines the correlations between each parameter in Japanese elderly people.

Patients and Methods

The 210 subjects had their ocular axial lengths measured with OA-2000. The endpoints were ocular axial length (AL), central corneal thickness (CCT), average anterior corneal radius of curvature (CR), white-to-white (WTW), anterior chamber depth (ACD), and lens thickness (LT). Our analyses utilized the eye with the longer AL in each person. Each parameter was analyzed for correlations in a round-robin manner. Regression analyses were performed on parameters correlated with AL.

Results

The parameters correlated with AL were CR (r = 0.33, P < 0.0001), WTW (r = 0.29, P < 0.0001), ACD (r = 0.59, P < 0.0001), and LT (r = -0.30, P < 0.0001). These parameters related to AL in all simple regression equations (CR (P < 0.0001), WTW (P = 0.0002), ACD (P < 0.0001), LT (P = 0.0001)). In multiple regression analyses, CR, ACD, and LT might relate to AL (CR (P = 0.0002), ACD (P < 0.0001), LT (P = 0.018)). LT tended to be thinner as AL increased, while CR, WTW, and ACD tended to increase.

Conclusion

This information may be useful in developing strategies for ophthalmic surgery, as it provides information on the location of intraocular tissues. Various parameters have been used in intraocular lens (IOL) power calculations in recent years and knowledge of the interrelationship among parameters may be useful in determining IOL power according to ethnicity in the future.

Clinical update in nanophthalmos: Features, diseases and complications associated

Nanophthalmos is a rare congenital condition of the eyeball that is characterised by a smaller size of the anterior and posterior segments without associated ocular malformations. Typical features that have traditionally been described in these eyes are short axial length, thickened sclera, cornea with a smaller diameter, narrow anterior chamber, and an increased lens to globe volume ratio. However, at present, there is still a lack of recognised diagnostic criteria for nanophthalmos and a classification of its severity. Its clinical relevance stems from the increased risk of multiple ocular conditions, such as high hyperopia, amblyopia, angle-closure glaucoma, retinal detachment, and cataracts. Likewise, in relation to surgery in these eyes, there are particularities in cataract and glaucoma surgery and with a greater risk of associated intra- and postoperative complications. In this way, the treatment of nanophthalmos focuses on controlling the associated eye conditions and reducing and controlling surgical complications. This review aims to update what has been published in recent years regarding nanophthalmos.

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.

Evaluation of ocular biometric parameters in keratoconic eyes relative to healthy myopic eyes

OBJECTIVE

To assess the biometric features of keratoconic eyes using the Lenstar LS900 and Pentacam systems relative to healthy myopic eyes.

MATERIALS AND METHODS

Seventy-three eyes of keratoconic subjects and 83 eyes of control subjects were enrolled. To evaluate the reproducibility of the Lenstar and Pentacam devices' measurements, keratometric readings [in flattest meridian (Kf), in steepest meridian (Ks), and mean (Km)], central corneal thickness (CCT), and anterior chamber depth (ACD) were obtained using both systems. Axial length and lens thickness (LT) were measured by the Lenstar. The compatibility between the two devices was investigated using the Bland-Altman statistical method.

RESULTS

Axial length was longer in the myopic group than in eyes with keratoconus (24.94  ±  0.7 and 23.88  ±  0.96 mm, respectively, p < 0.001). LT and vitreous depth were also higher in the myopic group, although ACD values were similar. Compared to the Lenstar, the Pentacam measured the ACD and CCT values higher in the myopia group [with a difference of 0.07  ±  0.12 mm (p <0.001) and 4.47  ±  11.33 µm (p  =  0.001), respectively] and measured the CCT values higher in the keratoconus group. Pentacam found all keratometry values significantly lower than Lenstar in the keratoconus group.

CONCLUSIONS

Axial length was longer in the myopic eyes due to the differences starting from the lens and extending to the posterior segment. Lenstar and Pentacam can be used interchangeably for Km, Kf, and ACD in the myopic group and only for ACD in the keratoconus group.

Intra-session repeatability of anterior chamber depth across the chamber width using Pentacam Scheimpflug imaging in healthy subjects

PURPOSE

Despite the importance of anterior chamber depth (ACD) measurements in disease and ageing, the repeatability and their threshold for change is not known. Our purpose was to determine the intra-session repeatability of Pentacam Scheimpflug photography for measuring the ACD across the chamber width in healthy subjects and thus inform expected limits of normality.

METHODS

Pentacam Scheimpflug photography was used to obtain ACD measurements at 57 points across the central 8mm of the chamber width from one randomly selected eye of 130 healthy (normal vision and no ocular diseases, except age-normal cataracts) subjects (median age 58.0 years, interquartile range 46.3-63.0 years; 48 males, 82 females). Intra-session ACD measurements were compared. Univariate and multivariate linear regression was performed to identify categorical and continuous variables demonstrating a significant relationship with ACD and its repeatability.

RESULTS

Bland-Altman analyses showed no directional or depth-dependent bias in the difference between the first and second tests (mean bias -0.003 mm, 95% limits of agreement -0.115 to +0.109 mm). Multivariate analysis found gender to be a significant factor (p < 0.0001), but not age (p = 0.69) nor ethnicity (p = 0.65), although the model fit was poor (R²  = 0.004). There were no regional differences in repeatability measures found in males, but six locations in the superior aspect in females were found to be significantly different in their repeatability characteristics. Tolerance limits used to calculate the number of step sizes between <20 and >60-year-old age groups found 8.1-11.5 steps for females, and 7.5-9.2 steps for males.

CONCLUSIONS

Scheimpflug imaging using the Pentacam has excellent intra-session repeatability. Only gender appeared to affect repeatability characteristics, manifesting with a greater number of meaningful steps of change between two extremes of age range in females compared to males, which provides guidance for identifying clinically significant and measurable change between tests.

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.

Corneal Biomechanics After Intrastromal Ring Surgery: Optomechanical In Silico Assessment

Purpose

To provide a biomechanical framework to better understand the postsurgical optomechanical behavior of the cornea after ring implantation.

Methods

Calibrated in silico models were used to determine the corneal shape and stresses after ring implantation. After mechanical simulations, geometric ray-tracing was used to determine the change in spherical equivalent. The effect of the surgical procedure, circadian variation of intraocular pressure, or the biomechanical weakening introduced by keratoconus (KC) were evaluated for each intrastromal ring.

Results

Models predicted the postsurgical optomechanical response of the cornea at a population level. The localized mechanical effect of the additional intrastromal volume introduced by the implants (size and diameter) drives the postsurgical corneal response. However, central corneal stresses did not increase more than 50%, and thus implants did not strengthen the cornea globally. Because of the biomechanical weakening introduced by laser pocketing, continuous implants in a pocket resulted in higher refractive corrections and in the relaxation of the anterior stroma, which could slow down KC progression. Implants can move within the stroma, acting as a dynamic pivot point that modifies corneal kinematics and flattens the corneal center. Changes in stromal mechanical properties did not impact on refraction for normal or pathological corneas.

Conclusions

Implants do not stiffen the cornea but create a local bulkening effect that regularizes the corneal shape by modifying corneal kinematics without canceling corneal motion.

Translational Relevance

In silico models can help to understand corneal biomechanics, to plan patient-specific interventions, or to create biomechanically driven nomograms.

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.

Anterior chamber depth measurement before and after photorefractive keratectomy. Comparison between IOLMaster and Pentacam

BACKGROUND

an accurate measurement of anterior chamber depth (ACD) both in eyes that underwent corneal refractive surgery (CRS) and in eyes that did not, can be crucial, as in case of intraocular lens (IOL) calculation in eyes that need to undergo cataract extraction, or during the evaluation of glaucomatous patients. The aim of this nonrandomized retrospective case series was to measure anterior chamber depth (ACD) before and after photorefractive keratectomy (PRK), comparing a rotating Scheimplfug camera (RSC) and a partial coherence interferometer (PCI).

METHODS

125 right eyes of 125 patients were examined. ACD was measured with RSC and a PCI preoperatively and 1, 3 and 6 months postoperatively. The results were analyzed using Friedman and ANOVA test for repeated measures, Wilcoxon test, Pearson and Bland-Altmann correlation.

RESULTS

Both instruments showed an ACD decrease after CRS. The mean preoperative difference in ACD between the two instruments was 0.11 ± 0.11 (range: -0.07 mm to 0.73 mm) (p < 0.05) (r = 0.92). The mean difference in ACD reduction between the two instruments was: 0.08 ± 0.11 (range: -0.35 to 0.39 mm) (p < 0.05, r = 0.93) at 1 month; 0.13 ± 0.11 (range: -0.09 mm to 0.48 mm) (p < 0.05, r = 0.93) at 3 months; 0.14 ± 0.15 (range: -0.16 to 0.82 mm) (p < 0.05) (r = 0.87), at 6 months.

CONCLUSIONS

The ACD decrease shown with both instruments suggests the presence of anterior segment remodeling after PRK. RSC measurements were larger than PCI ones, both before and after PRK.

Evaluation of biometric parameters in phacomorphic glaucoma and mature cataracts

PURPOSE

The aims of this study were to compare the biometric parameters and axial lengths of eyes with phacomorphic glaucoma and mature cataract and to identify differences that might predispose to development of phacomorphic glaucoma.

METHODS

Three hundred forty-two patients were enrolled in this retrospective study. The eyes were divided into four groups-Group (G)1: phacomorphic glaucoma (n = 29), G2: mature cataract (n = 313), G3: contralateral phacomorphic glaucoma (n = 29), and G4: contralateral mature cataract (n = 313). Central corneal thickness and anterior chamber depth were assessed by optical low-coherence reflectometry (Lenstar LS 900®; Haag-Streit AG, Switzerland), while axial length was determined by A-scan ultrasound biometry.

RESULTS

The mean central corneal thickness of G1 was significantly higher than in other groups (p < 0.001) and the mean anterior chamber depth of G1 was the lowest among the groups (p < 0.001). Also, G2 had lower mean anterior chamber depth than G4 (p < 0.001) and G3 had lower mean anterior chamber depth than G4 (p = 0.007). Anterior chamber depth less than 3.27 mm had the higher odds ratio for distinguishing G3 versus G4 (odds ratio = 10.79, p < 0.001). Furthermore, patients aged ⩾68.9 years had the higher odds ratio for distinguishing G1 versus G2 (odds ratio = 2.82, p = 0.019). There was no significant difference in the presence of pseudoexfoliation material between G1 and G2 (p = 0.057). There were no significant differences in axial length values among the four groups (p = 0.097).

CONCLUSION

Advanced age and shallow anterior chamber depth were found to be risk factors for developing phacomorphic glaucoma, but the presence of pseudoexfoliation material was not found to play a role as a risk factor in phacomorphic glaucoma development.

Measurement of the depths at different regions of the anterior chamber in healthy Chinese adults

AIM

To measure the depths of different regions of the anterior chamber (AC) in healthy Chinese adults, and to explore possible correlations with age or gender.

METHODS

The AC was imaged by swept-source optical coherence tomography in healthy Chinese adults. The horizontal scan of the right eye was used to measure the anterior chamber depth (ACD) at 199 points.

RESULTS

A total of 309 images from 309 subjects were analyzed. The ACD values at nearly all locations were negatively correlated with age (all P<0.05), except for ACD1, 2, 198, and 199 (correspond to the iris roots). The mean annual decrease 0.013±0.005 mm/y for all ACDs combined, 0.008±0.004 mm/y for the peripheral region, 0.017±0.003 mm/y for the middle peripheral region, and 0.014±0.001 mm/y for the central region. The mean annual decrease was significantly different among these three regions (P<0.001). The ACD was greater in males than in females (P<0.05). The mean difference in ACD between males and females was 0.081±0.025 mm.

CONCLUSION

This study showed that optical coherence tomography can be used to measure the ACD of different regions of the AC. We found reductions in ACD with age, although the reduction varied among different points, in healthy Chinese adults.

Correlations between ocular biometrics and refractive error: A systematic review and meta-analysis

The understanding of correlations between different biometric parameters is essential for personalized eye care in the field of cataract and refractive surgery. This systematic review offers a clear overview of the previous literature assessing these correlations including a meta-analysis. The review is focused on the following five correlations: (1) axial length and refractive error; (2) anterior chamber depth and refractive error; (3) axial length and anterior chamber depth; (4) corneal power and refractive error; (5) corneal power and axial length. An expected strong correlation between axial length and refractive error was found. Correlations including corneal power were weak and might be clinically insignificant.

Normative database and determinants of macular vessel density measured by optical coherence tomography angiography

IMPORTANCE

To provide a normative vessel density (VD) database for the macula through swept-source optical coherence tomography angiography (OCTA) and to assess the main determinants of this measurement.

BACKGROUND

In contrast with dye angiography, the recently introduced OCTA technique allows for the non-invasive measurement of retinal and choroidal VD metrics.

DESIGN

Cross-sectional study.

PARTICIPANTS

The right eyes of 346 healthy subjects were studied. In 105 subjects both eyes were imaged.

METHODS

Foveal and parafoveal macular VD measurements were obtained in the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), and in the choriocapillaris (CC) layer. Also recorded were age, sex, axial length (AL), foveal and choroidal thickness (CT).

MAIN OUTCOME MEASURES

Normative database and determinants of macular VD measured by OCTA.

RESULTS

Mean participant age was 38.3 ± 20.1 years (mean ± SD) (range 5-83). Foveal VDs in the different plexuses were: SCP 22.1% ± 5.0% (7.3-35.1), DCP 19.9% ± 6.3% (6.9-51.2) and CC: 52.8% ± 4.3% (40.2-62.1). Parafoveal VDs ranged from 45.4% ± 3.7% to 51.8% ± 4.6%. Positive correlation was observed between foveal VD and foveal thickness (R = .327), as well as between parafoveal DCP VD and CT (R = .250;P ≤ .006), while correlation with age was negative in the SCP and CC (R = -.283;P < .001). No associations were detected between macular VD and sex or AL (P ≥ .05).

CONCLUSION AND RELEVANCE

Macular VD showed wide individual variation, was positively correlated with foveal thickness and with CT, negatively correlated with age, and showed no correlation with AL or sex.

Reduced aqueous humour ascorbic-acid concentration in women with smaller anterior chamber depth

Short anterior chamber depth (ACD) is considered a risk factor of endothelial-cell loss after phacoemulsification. However, whether it is an independent risk factor or not remains controversial. We investigated the relationship between ascorbic acid (AA) concentrations in the aqueous humour (AqH) and ACD. We analysed 165 AqH samples of 97 patients (42 men and 55 women) who underwent small incision cataract surgery. AqH and plasma AA concentrations were measured using a high-performance liquid chromatography - electrochemical detection method. Patient characteristics were compared between and within the sexes. As a result, age and ACD were significantly correlated with AqH AA concentrations (r = −0.206, P = 0.045; r = 0.339, P < 0.001) only in women. Moreover, plasma AA concentrations were significantly correlated with AqH AA concentrations (r = 0.420, P < 0.001; r = 0.316, P = 0.002) both in men and women. After adjusting for confounding factors (age and plasma AA concentrations), ACD was significantly and positively correlated with AqH AA concentrations (partial.r = 0.275, P = 0.009) only in women. In conclusion, AqH AA concentrations were reduced in women with smaller ACD. This may suggest that women with short ACD could be more susceptible to oxidative damage.

Observation of anterior chamber volume after cataract surgery with swept-source optical coherence tomography

PURPOSE

To investigate the changes in the anterior chamber volume (ACV) with swept-source optical coherence tomography (SS-OCT) after cataract surgery and the factors that influence these ACV changes.

METHODS

This was a prospective cohort study. Fifty-one patients who underwent cataract surgery were enrolled. Their ACV, anterior chamber depth, and angle widths were measured with SS-OCT before and 1 day, 1 week, and 1 month after surgery. The associations between the changes in ACV and posterior vitreous detachment (PVD) and axial length (AXL) were determined.

RESULTS

Compared with the preoperative volume, ACV increased significantly at all three time points after surgery (all p < 0.001). ACV was greater at 1 week after surgery than at 1 day after surgery (p < 0.001). Both AXL and the presence of PVD were significantly associated with the change in ACV at 1 day after surgery (p = 0.005). However, neither PVD nor AXL affected the change in ACV between 1 day and 1 week after surgery.

CONCLUSIONS

ACV stabilized in the first week after cataract surgery. The absorption of irrigation fluid and balanced salt solution in the vitreous cavity contributed to the change in ACV 1 week after surgery. Eyes with longer AXL and PVD tended to show less change in ACV at 1 day after surgery.

Steeper Iris Conicity Is Related to a Shallower Anterior Chamber: The Gutenberg Health Study

PURPOSE

To report the distribution of iris conicity (steepness of the iris cone), investigate associated factors, and test whether pseudophakia allows the iris to sink back.

METHODS

A population-based cross-sectional study was carried out. Ophthalmological examination including objective refraction, biometry, noncontact tonometry, and Scheimpflug imaging (Pentacam®, Oculus) was performed including automated measurement of iris conicity. 3708 phakic subjects, 144 subjects with bilateral and 39 subjects with unilateral pseudophakia were included. Multivariable analyses were carried out to determine independently associated systemic and ocular factors for iris conicity in phakic eyes.

RESULTS

Mean iris conicity was 8.28° ± 3.29° (right eyes). Statistical analysis revealed associations between steeper iris conicity and shallower anterior chamber depth, thicker human lens and higher corneal power in multivariable analysis, while older age was related to a flatter iris conicity. Refraction, axial length, central corneal thickness, pupil diameter, and intraocular pressure were not associated with iris conicity. Pseudophakia resulted in a 5.82° flatter iris conicity than in the fellow phakic eyes.

CONCLUSIONS

Associations indicate a correlation between iris conicity with risk factors for angle-closure, namely, shallower anterior chamber depth and thicker human lens. In pseudophakic eyes, iris conicity is significantly lower, indicating that cataract surgery flattens the iris.

Evaluation of Anterior Chamber Volume in Cataract Patients with Swept-Source Optical Coherence Tomography

Purpose. To evaluate the anterior chamber volume in cataract patients with Swept-Source Optical Coherence Tomography (SS-OCT) and its influencing factors. Methods. Anterior chamber volume of 92 cataract patients was evaluated with SS-OCT in this cross-sectional study. Univariate analyses and multiple linear regression were used to investigate gender, age, operated eye, posterior vitreous detachment, lens opacity grading, and axial length (AXL) related variables capable of influencing the ACV. Results. The average ACV was 139.80 ± 38.21 mm³ (range 59.41 to 254.09 mm³). The average ACV was significantly larger in male patients than in female patients (P = 0.001). ACV was negatively correlated with age and LOCS III cortical (C) grading of the lens (Pearson's correlation analysis, r = −0.443, P < 0.001, and Spearman's correlation analysis, ρ = −0.450, P < 0.001). ACV was also increased with AXL (Pearson's correlation analysis, r = 0.552, P < 0.001). Multiple linear regression showed that, with all of the covariates entered into the model, gender (P = 0.002), age (P = 0.015), LOCS III C grade (P = 0.043), and AXL (P = 0.001) were still associated with ACV (F = 10.252  P < 0.001  R² = 0.498). Conclusion. With SS-OCT, we found that, in healthy cataract patients, ACV varied significantly among different subjects. Influencing factors that contribute to reduced ACV were female gender, increased age, LOCS III C grade, and shorter AXL.

Agreement Between Swept-Source Optical Biometry and Scheimpflug-based Topography Measurements of Anterior Segment Parameters

PURPOSE

To estimate the agreement of anterior segment parameters between a swept-source optical biometry (IOLMaster 700; Carl Zeiss Meditec AG, Jena, Germany) and a Scheimpflug-based topography with high resolution (Pentacam HR; OCULUS, Wetzlar, Germany).

DESIGN

Interinstrument reliability analysis.

METHODS

A total of 62 eyes from 62 young adults were included in the study. Average keratometry (AveK) and simulated keratometry (SimK) along 2.0-mm-ring measurements provided by Pentacam HR, keratometry readings provided by IOLMaster 700, and central corneal thickness (CCT) and anterior chamber depth (ACD) values obtained from both devices were recorded. J0 and J45 vectoral components of astigmatism were obtained using power vector analysis. Mean keratometry (Km) values of IOLMaster 700 were compared for each type of Km value from Pentacam HR, while other parameters were compared between devices. To assess the agreement between measurements of the devices, Bland-Altman analysis was performed.

RESULTS

The Pentacam HR exhibited significantly lower Km and CCT measurements (P < .001, for all); however, no significant difference emerged in J0, J45, and ACD measurements (P = .057, P = .574, and P = .64, respectively). The mean difference between AveK, SimK 2.0 mm, and the IOLMaster 700 Km was -0.20 diopter (D) and -0.14 D, respectively, while the mean difference between J0, J45, CCT, and ACD measurements was 0.07 D, -0.016 D, -5.05 μm, and 0.004 mm, respectively.

CONCLUSION

In clinical practice, Pentacam HR and IOLMaster 700 can be used interchangeably to measure J0 and J45 vectoral components of astigmatism for SimK 2.0 mm and IOLMaster keratometry values, as well as ACD and CCT measurements. However, SimK 2.0 mm and AveK values can be not interchangeable, as the devices have clinical and statistical differences in measurements.

Spectral domain optical coherence tomography to assess the insertion of extraocular rectus muscles

PURPOSE

To determine the distance of the horizontal rectus muscle insertion to the limbus using spectral domain optical coherence tomography (SD-OCT) and to evaluate whether results are correlated with sex, age, or axial length.

METHODS

The right eyes of healthy, white subjects were imaged with SD-OCT. Subjects' sex and age were recorded, and axial length was measured using an optical biometer. The distance from the horizontal rectus insertion to the limbus was measured. The intraclass correlation coefficient (ICC) was used to assess the reproducibility of the measurements with a subset of images. A multivariate model was adjusted to analyze whether sex, age, and axial length was correlated with insertion distance.

RESULTS

A total of 187 right eyes were included. Mean participant age was 43.7 ± 22.1 years (range, 6-85). Of the 187 patients, 129 were female; 25 were children. Mean axial length was 23.9 ± 1.6 mm (range, 20.4-29.3). Mean rectus insertion distance to the limbus was 6.47 ± 0.52 mm (range, 5.2-7.6 mm) for the lateral rectus muscle and 5.22 ± 0.51 mm (range, 4.1-6.1 mm) for the medial rectus muscle. ICC was >0.87 for intra- and interobserver reproducibility. The insertion-limbus distance was correlated with sex, being greater in males (P = 0.040 for the lateral rectus muscle; P = 0.036 for medial rectus muscle). There was no correlation between this distance and axial length or age (P > 0.156).

CONCLUSIONS

In this study cohort, the insertion distance of the horizontal rectus muscles to the limbus on SD-OCT was greater in males than females; however, age and axial length were not correlated with insertion distance.