Analysis of Lens Thickness Distribution Based on Swept-Source Optical Coherence Tomography (SS-OCT)

Biometric description of 34 589 eyes undergoing cataract surgery: sex differences

PURPOSE

To describe gender differences in the biometric parameters of a large sample of patients with cataract. Cataract surgery has evolved from a vision restoration to a refractive procedure, and population-based studies are vital to optimize normative databases and postsurgical outcomes.

SETTING

Miguel Servet University Hospital, Zaragoza, Spain.

DESIGN

Retrospective single-center observational study.

METHODS

The study included 34 589 eyes (20 004 patients with cataract). Biometric data were obtained from IOL Master 700 and Pentacam HR. Linear mixed models were used to account for intereye correlation. HofferQST formula was used to calculate the hypothetical distribution of intraocular lens (IOL) power (arbitrary lens; A = 119.2).

RESULTS

Most biometric variables showed significant differences between sexes ( P < .0001), such as 0.53 mm shorter eyes found in females, of which 0.16 mm are explained by shorter aqueous depth. Steeper anterior keratometries (∼0.75 diopter [D]) were found in women, to end up in no difference on anterior astigmatism magnitude, but different orientation ( P < .0001). The distribution of IOL power differed between sexes ( P < .001), with the interquartile range shifting 1 D toward more powerful lenses in women and odds ratio (power >26 D) = 2.26, P < .0001 (Fisher).

CONCLUSIONS

Large sample size studies provide smaller margin of error, higher power, and controlled risk of reporting false (negative or positive) findings. Highly significant differences between sexes in ocular biometry were found; this supports the idea that including sex as a parameter in IOL calculation should be explored and may improve results. In addition, the distribution of IOL powers was provided, which may be useful for manufacturers and hospital stock planning.

Senile Cataract Formation Does Not Affect Crystalline Lens Thickness

INTRODUCTION

Characterizing lens thickness (LT) in patients with cataracts is important for better understanding the lens aging process and for designing new intraocular lens power formulas. This study aimed to analyze the influence of common senile cataract formation on the LT, anterior (ACS) and posterior (PCS) cortex space, and nuclear thickness (NT), controlling for sex, age, and axial length.

METHODS

A cross-sectional study was performed. A consecutive sample of 603 volunteers (403 women, 200 men) aged 59.1 ± 18.8 years was recruited. The standardized Lens Opacification Classification System (LOCS)-III was used to classify eyes (randomly selected) into cataractous and non-cataractous groups. Also, they were classified according to the cataract location (presence or absence of cortical, nuclear, or posterior subcapsular cataract). Optical biometry was performed to measure LT, ACS, NT, and PCS. Propensity score was used to match participants one-to-one for sex, age, and axial length. Groups were compared using the Student's t test or Yuen's test.

RESULTS

The four classifications divided unmatched eyes into: 361 cataractous lenses and 242 non-cataractous, 226 cortical and 377 non-cortical cataractous, 313 nuclear and 290 non-nuclear cataractous and 242 subcapsular and 361 non-subcapsular cataractous. Before matching, cataractous eyes showed significantly higher LT (4.52 ± 0.39 vs. 3.94 ± 0.46 mm, p < 0.001), ACS (0.75 ± 0.20 vs. 0.58 ± 0.23 mm, p < 0.001), NT (3.34 ± 0.23 vs. 3.18 ± 0.25 mm, p < 0.001) and PCS (0.42 ± 0.19 vs. 0.37 ± 0.19 mm, p = 0.003). Matched lens, cortical, nuclear, and subcapsular cataract samples comprised 146, 258, 182, and 226 eyes, respectively. After matching, no significant differences were observed in LT (4.34 ± 0.37 vs. 4.33 ± 0.36 mm, p = 0.94), ACS (0.72 ± 0.20 vs. 0.76 ± 0.19 mm, p = 0.08), NT (3.31 ± 0.22 vs. 3.30 ± 0.23 mm, p = 0.24) and PCS (0.42 ± 0.19 vs. 0.43 ± 0.16 mm, p = 0.79).

CONCLUSIONS

The presence of senile cortical, nuclear, and posterior subcapsular cataract have no effect on LT, ACS, NT, and PCS. Confounding factors should be controlled for when measuring LT and its main components.

Central anterior chamber depth correlated with white-to-white distance in normal, long, and short eyes

PURPOSE

To explore the associations between central anterior chamber depth (CACD) and other anterior segment biometric parameters and to determine the possible determinants of CACD in short, normal, and long eyes.

METHODS

The biometric data of pre-operation patients aged 50-80 years with coexisting cataract and primary angle-closure disease or senile cataract were reviewed. Axial length (AL), CACD, lens thickness (LT), central corneal thickness (CCT), and white-to-white distance (WTW) were measured by Lenstar optical biometry (Lenstar 900). The data of 100 normal eyes (AL = 22 to 26 mm), 100 short eyes (AL ≤ 22 mm), and 100 long eyes (AL ≥ 26 mm) were consecutively collected for subsequent analyses.

RESULTS

The mean age of the subjects was 66.60 ± 7.85 years, with 25.7% of the sample being men. Both CACD and WTW were found to be smallest in short eyes and were smaller in normal eyes than in long eyes (F = 126.524, P < 0.001; F = 28.458, P < 0.001). The mean LT was significantly thicker in short eyes than in normal and long eyes (4.66 mm versus 4.49 mm versus 4.40 mm; F = 18.099, P < 0.001). No significant differences were observed in CCT between the three AL groups (F = 2.135, P = 0.120). Stepwise regression analysis highlighted AL, LT, and WTW as three independent factors associated with CACD in the normal AL group. In the short AL group and long AL group, LT and WTW were independent factors associated with CACD.

CONCLUSIONS

CACD increases as AL elongates and reaches a peak when AL exceeds 26 mm. Furthermore, CACD showed inverse correlation with LT and positive correlation with WTW. A relatively small WTW results in an anteriorly positioned lens, and thus, a decrease in CACD.

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.

Refractive Status and Biometric Characteristics of Children With Familial Exudative Vitreoretinopathy

Purpose

To compare biometric characteristics between patients with early-stage familial exudative vitreoretinopathy (FEVR) and healthy controls.

Methods

This case-control study included 50 FEVR eyes in stage 1-2 and 50 control eyes matched by age, gender and spherical equivalent (SE). Biometric parameters including axial length (AL), white-to-white diameter (WTW), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), pupil diameter, vitreous chamber depth, anterior and posterior corneal surface curvature radius (ACR and PCR), anterior lens surface curvature radius (ALR) and posterior lens surface curvature radius were measured using IOLMaster 700 and compared between cases and controls using paired t-test. Correlations between SE and biometric measures were assessed using Pearson correlation coefficient (r) in cases and controls.

Results

Both FEVR cases and matched controls had a mean age of 7.6 years, 48% female and mean SE of -5.3 D (80% myopia). Compared to controls, FEVR eyes had smaller AL (P = 0.009), WTW (P = 0.001), ACD (P < 0.001), and ALR (P = 0.03), but larger CCT (P = 0.02) and LT (P = 0.01). In FEVR eyes, SE was negatively correlated with AL (r = -0.79, P < 0.001), positively correlated with ACR (r = 0.29, P = 0.04) and PCR (r = 0.33, P = 0.02), whereas in controls, SE was negatively correlated with AL (r = -0.82, P < 0.001) and LT (r = -0.34, P = 0.02), positively correlated with ALR (r = 0.29, P = 0.04).

Conclusions

Patients at early stage of FEVR exhibited a unique eye morphology resembling ocular development arrest, which may help to develop screening and early detection tools for FEVR. In FEVR patients, myopia is very prevalent and significantly associated with corneal curvature increase.

Clinical applications of anterior segment swept-source optical coherence tomography: A systematic review

Optical coherence tomography (OCT) is a non-invasive method that provides the opportunity to examine tissues by taking cross-sectional images. OCT is increasingly being used to evaluate anterior segment (AS) pathologies. Swept-source (SS) OCT allows greater penetration and achieves better visualization of the internal configuration of AS tissues due to the longer wavelength employed and high scan speeds. We reviewed the utilization of AS SS-OCT in various conditions including glaucoma, ocular surface pathologies, iris tumors, refractive surgery, cataract surgery, and scleral diseases. A systematic literature search was carried out on PubMed, Scopus, and Web of Science databases between January 1, 2008, and September 1, 2022 using the following keywords: AS SS-OCT; dry eye and SS-OCT; ocular surface and SS-OCT; cornea and SS-OCT; dystrophy and SS-OCT; glaucoma and SS-OCT; ocular surface tumors and SS-OCT; conjunctival tumors and SS-OCT; refractive surgery and SS-OCT; cataract and SS-OCT; biometry and SS-OCT; sclera and SS-OCT; iris and SS-OCT; ciliary body and SS-OCT; artificial intelligence and SS-OCT. A total of 221 studies were included in this review. Review of the existing literature shows that SS-OCT offers several advantages in the diagnosis of AS diseases. Exclusive features of SS-OCT including rapid scanning, deeper tissue penetration, and better image quality help improve our understanding of various AS pathologies.

Comparison of anterior segment parameters in myopia with and without primary open-angle glaucoma

PURPOSE

To compare anterior segment parameters between myopes with and without primary open-angle glaucoma using Pentacam scheimpflug tomography.

METHODS

This was a single-center retrospective cross-sectional study. Records of patients examined with a Pentacam scheimpflug tomographer (Wavelight-Allegro Oculyzer, GmbH, Erlangen, Germany) were reviewed. Variables studied were recorded from the topographic map and included anterior chamber angle, anterior chamber volume, anterior chamber depth, keratometric readings, and corneal thickness. A general linear model for age-and spherical equivalent refraction-adjusted intergroup comparisons of the anterior segment parameters was conducted.

RESULTS

The study included myopes previously diagnosed with primary open-angle glaucoma (POAG) [Mild defect, n = 81; Moderate-severe defect, n = 50] and non-glaucomatous myopes (n = 247). The results revealed a smaller anterior chamber angle, shallower anterior chamber depth, and flatter cornea curvature in the mildly glaucomatous group compared to the non-glaucomatous group (p < 0.05). Smaller anterior chamber angle, shallower anterior chamber depth, and thinner cornea thickness were also observed in the moderate-severely glaucomatous group compared to the non-glaucomatous group (p < 0.05).

CONCLUSION

Glaucomatous damage in myopic patients with POAG was associated with comparatively small anterior chamber angle, shallow anterior chamber depth, flat cornea curvature, and thin cornea.