Impact of tear optics on the repeatability of Pentacam AXL wave and iTrace in measuring anterior segment parameters and aberrations

Development of a dry eye index as a new biomarker of dry eye disease

PURPOSE

To evaluate signs and symptoms in patients diagnosed with dry eye disease (DED), divided into dry eye (DE) groups, in order to find a new biomarker that allows an accurate diagnosis, management and classification of DED.

METHODS

This cross-sectional, observational study included 71 DED subjects. Subjective symptoms, visual quality and DE signs were assessed using the Ocular Surface Disease Index (OSDI), the Quality of Vision (QoV) questionnaire, best corrected distance visual acuity (VA), functional visual acuity (FVA), contrast sensitivity (CS), high- and low-order corneal aberrations (HOA and LOA, respectively), tear break-up time (TBUT), Meibomian Gland Dysfunction (MGD), Schirmer test, corneal staining, lid wiper epitheliopathy (LWE) and meibography. Participants were classified into three groups based on dryness severity using a cluster analysis, i.e., mild (N = 17, 55.8 ± 15.4 years), moderate (N = 41, 63.5 ± 10.6 years) and severe (N = 13, 65.0 ± 12.0). A new Dry Eye Severity Index (DESI) based on ocular surface signs has been developed and its association with symptoms, visual quality and signs was assessed. Comparisons between groups were made using Kruskal-Wallis and Chi-squared tests. Spearman correlation analysis was also performed.

RESULTS

The DESI was based on three tests for DE signs: TBUT, Schirmer test and MGD. The DESI showed significant differences between different pairs of groups: Mild Dryness versus Moderate Dryness (p < 0.001), Mild Dryness versus Severe Dryness (p < 0.001) and Moderate Dryness versus Severe Dryness (p < 0.001). The DESI was significantly correlated with age (rho = -0.30; p = 0.01), OSDI score (rho = -0.32; p = 0.007), QoV score (rho = -0.35; p = 0.003), VA (rho = -0.34; p = 0.003), FVA (rho = -0.38; p = 0.001) and CS (rho = 0.42; p < 0.001) Also, significant differences between the severity groups were found for OSDI and QoV scores, VA, FVA, CS and MGD (p < 0.05).

CONCLUSIONS

The DESI has good performance as a biomarker for the diagnosis, classification and management of DED.

Swept-source optical coherence tomography in ocular surface diseases: anterior segment analysis repeatability and its limits

Purpose

This study aims to evaluate the repeatability of anterior segment optical coherence tomography (AS-OCT) in diverse ocular surface disorder (OSD) cohorts, exploring various anterior segment parameters and their accuracy in different disease groups.

Methods

A total of 239 participants across six distinct OSD groups and healthy controls underwent nonmydriatic AS-OCT imaging using the Tomey CASIA 2 device. Anterior segment parameters including anterior chamber depth, width, angle metrics, corneal thickness, keratometry, lens vault, and others were meticulously assessed. Statistical analyses determined repeatability limits and coefficients of variation for each parameter within the different OSD cohorts.

Results

Repeatability for anterior chamber and corneal parameters remained consistent across all OSD groups, indicating minimal impact of ocular surface disease on accuracy. The coefficient of variation (CoV) for the trabecular iris-space area was about 20% for all cohorts. Ocular surface inflammation emerged as a key factor in dry eye, affecting immune-mediated and non-immune conditions alongside age-related ocular surface changes. While anterior chamber depth measurements showed variations, particularly in immune (CoV = 2.5%) and non-immune (CoV = 3.8%) OSD groups, parameters like anterior chamber width and angle to angle showed similar values among the cohorts. Keratometry measures remained stable despite OSD (CoV lower than 1%).

Conclusion

The Tomey CASIA 2 demonstrated reliable repeatability for measuring anterior segment parameters in diverse OSD cohorts. Despite challenges posed by dry eye conditions, this technology holds promise in assessing OSD, suggesting potential clinical protocols similar to those in healthy controls.

Agreement between IOLMaster 700 and Pentacam AXL for IOL power measurement in patients with high myopia

PURPOSE

The anterior segment in individuals with high myopia has different features compared to those without myopia. IOLMaster 700 and Oculus Pentacam AXL are two accurate optical biometers. Both devices measure the cornea differently and thus yield different results when measuring intraocular lens (IOL) power. The purpose of this study is to assess the agreement of the IOL power calculation between IOLMaster 700 and Oculus Pentacam AXL in patients with high myopia.

METHODS

A prospective, analytical cross-sectional study was conducted to assess the agreement between the IOL power calculation with IOLMaster 700 and Oculus Pentacam AXL. In this study, 44 eyes were examined using Oculus Pentacam AXL and IOLMaster 700, and IOL power was calculated using the Barret Universal II formula and the AMO Sensar AR40E. The Bland-Altman plot was used to evaluate the agreement between the two devices.

RESULTS

Based on the IOLMaster 700 examination, 44 eyes with high myopia had axial lengths ranging from 26.05 to 34.02 mm. The mean IOL power was 8.26 ± 4.755 and 8.58 ± 4.776 based on IOLMaster 700 and Oculus Pentacam AXL, respectively. The Bland-Altman plot revealed good agreement between the two devices, with a mean difference of -0.3182 in the IOL power calculation and a 95% LoA of 0.88099-0.24462 with a 95% confidence interval.

CONCLUSION

Both devices showed good agreement in the IOL power calculation in patients with high myopia.

Evaluation of the Agreement Between a New Pyramid Wavefront Sensor Aberrometer and Scheiner-Smirnov Aberrometers

PURPOSE

To assess agreement between a new aberrometer (Osiris-T; CSO) employing pyramid wavefront sensor technique and Scheiner-Smirnov aberrometer (OPD-Scan III; Nidek) on measuring ocular, corneal, and internal aberrations in healthy participants.

METHODS

The measurements were conducted three times consecutively by an experienced examiner. The total root mean square (RMS) aberrations, higher order aberration RMS, coma Z3±1, trefoil Z3±3, spherical aberration Z40, and astigmatism II Z4±2 up to 7th order were exported in both 4-and 6-mm pupil zones. The parameters between the two devices were statistically compared using the paired t-test, and the differences assessed with Bland-Altman plots and 95% limits of agreement.

RESULTS

This prospective study included 70 right eyes of 70 healthy participants with an average age of 25.94 ± 6.59 years (range: 18 to 47 years). The mean difference in the two devices ranged from 0.01 µm for astigmatism II Z4±2 to 0.63 µm for total RMS in 4 mm and from 0.01 to 1.41 µm in 6-mm pupil size. The Bland-Altman analysis of ocular, corneal, and internal aberrations indicated high agreement between the two devices and the maximum absolute values for 95% limits of agreement ranged from 0.03 to 1.06 µm for 4-mm pupil diameters and 0.12 to 1.13 µm for 6-mm pupil diameters.

CONCLUSIONS

The newly developed pyramid wavefront sensor technique aberrometer demonstrated a high agreement with a Scheiner-Smirnov aberrometer when measuring ocular, corneal, and internal aberrations in healthy participants. Thus, the two aberrometers may be considered interchangeable for clinical applications. [J Refract Surg. 2024;40(4):e218-e228.].

A Comprehensive Wavefront Assessment of Keratoconus Using an Integrated Scheimpflug Corneal Tomographer/Hartmann-Shack Wavefront Aberrometer

OBJECTIVES

To characterize higher-order aberrations (HOAs) in different severities of keratoconus (KC) from the anterior and posterior corneal surfaces and whole eye using an integrated Scheimpflug corneal tomographer/Hartmann-Shack wavefront aberrometer.

METHODS

This study included eyes with clinical KC, topographic KC (no clinical signs), fellow eyes with very asymmetric ectasia with normal topography and no clinical signs (VAE-NT), and control eyes. Corneal and ocular wavefront aberrations were obtained using an integrated Scheimpflug tomographer/Hartmann-Shack wavefront aberrometer. The diagnostic capability of distinguishing VAE-NT from the control was also tested.

RESULTS

This study included 68 eyes with clinical KC, 44 with topographic KC, 26 with VAE-NT, and 45 controls. Clinical KC had significantly greater total HOAs and coma from the anterior and posterior corneal surfaces and whole eye than the other groups ( P <0.05). Although topographic KC had significantly greater values in all wavefront parameters than the control ( P <0.05), ocular and corneal HOAs did not differ between the VAE-NT and control groups. The coma from the anterior cornea in topographic KC was significantly greater than that in VAE-NT ( P <0.05); the coma from the posterior cornea and whole eye did not differ. Total HOAs from the anterior corneal surface exhibited the highest area under the receiver operating characteristic curve value of 0.774 (sensitivity, 73%; specificity, 78%).

CONCLUSION

A comprehensive wavefront assessment can be used to quantitatively evaluate corneal and ocular HOAs across various severity of KC. Total HOAs from the anterior corneal surface exhibited the potential ability in distinguishing VAE-NT from the control eyes.

Comparison of Total Corneal Astigmatism between IOLMaster and Pentacam

Purpose. To compare the total corneal astigmatism (TCA) measured by IOLMaster 700 and Pentacam and to investigate the consistency of corneal keratometry (CK) measured by IOLMaster and Pentacam. Methods. Cataract patients were retrospectively enrolled in March and April, 2021. Retrospective analysis was performed on those patients with binocular and monocular CK measured by IOLMaster and Pentacam. Results. A total of 102 patients (204 eyes) were included, 64 of whom were female (62.75%). The flat (K1) and steep (K2) CK of anterior corneal surface (ACS) and flat (TK1) and steep (TK2) of total cornea measured with IOLMaster 700 were $44.16\pm 1.60\text{D}$ , $45.09\pm 1.68\text{D}$ , $44.12\pm 1.62\text{D}$ , and $45.14\pm 1.69\text{D}$ , respectively. Those measured with Pentacam were $44.31\pm 1.57\text{D}$ , $45.22\pm 1.65\text{D}$ , $44.15\pm 1.67\text{D}$ , and $45.19\pm 1.82\text{D}$ , respectively. The astigmatism of ACS and TCA were $-0.94\pm 0.63\text{D}$ and $-1.02\pm 0.69\text{D}$ ( $p<0.01$ ) in the IOLMaster group and $-0.90\pm 0.59\text{D}$ and $-1.05\pm 0.81\text{D}$ in the Pentacam group, respectively ( $p<0.01$ ). TCA measurement results of IOLMaster and Pentacam were consistent ( $\text{Pearson}=0.710$ , $p<0.01$ ), and there was no significant difference ( $p=0.591$ ). Conclusions. Total corneal astigmatism measured by IOLMaster was consistent with that measured by Pentacam. The difference between the astigmatism of anterior corneal surface and total cornea was detected in the measurement of IOLMaster and Pentacam, respectively.