Corneal power measurement with a rotating Scheimpflug imaging system after Descemet-stripping automated endothelial keratoplasty

Purpose. To compare the higher-order aberrations (HOAs) due to the anterior and posterior corneal surfaces in patients that underwent either Descemet-stripping-automated-endothelial-keratoplasty (DSAEK) or penetrating keratoplasty (PK) for endothelial dysfunction and age-matched controls. Methods. This retrospective, observational, case series included 28 patients after PK, 30 patients after DSAEK, and 30 healthy controls. A Scheimpflug imaging system was used to assess the HOAs due to the anterior and posterior corneal surfaces at 4 mm and 6 mm optical zones. Total, 3rd and 4th order HOAs were considered. Intra- and intergroup differences were assessed using the Friedman and the Kruskal-Wallis tests, respectively; paired comparisons were performed using Duncan's multiple range test. Results. Total, 3rd and 4th order HOAs due to both corneal surfaces at 4 mm and 6 mm optical zones were significantly higher in the PK group, intermediate in the DSAEK group, and lower in controls (). The most important HOAs components in both PK and DSAEK groups were trefoil and coma from the anterior corneal surface () and trefoil from the posterior corneal surface (). Conclusions. The optical quality of both corneal surfaces appeared significantly higher after DSAEK than after PK, which can increase the postoperative patient's quality of vision and satisfaction.

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Comparison of total keratometry with corneal power measured by optical low-coherence reflectometry and placido-dual Scheimpflug system

European Journal of Ophthalmology ◽

10.1177/11206721211020633 ◽

2021 ◽

pp. 112067212110206

Author(s):

Usha Bhanu Kommineni ◽

Ashik Mohamed ◽

Pravin K Vaddavalli ◽

Jagadesh C Reddy

Keyword(s):

Cataract Surgery ◽

Imaging System ◽

Mean Difference ◽

Swept Source ◽

Corneal Power ◽

Low Coherence ◽

Scheimpflug Imaging ◽

The Mean ◽

Power Measurements ◽

Optical Low Coherence Reflectometry

Purpose: To compare the total keratometry (TK) and astigmatism measurements in eyes with cataract using automated keratometry of swept-source optical coherence tomography (ss-OCT), optical low-coherence reflectometry (OLCR), simulated keratometry (SimK), and total corneal power (TCP) of combined placido-dual Scheimpflug imaging system. Setting: The study was conducted at LV Prasad Eye Institute, Hyderabad, India. Design: Retrospective evaluation of electronic medical records of patients who were evaluated for cataract surgery Methods: Twenty-eight eyes of 28 patients were included in the study. All patients evaluated for cataract surgery underwent corneal power measurements using three devices: ssOCT, OLCR, and combined placido-dual Scheimpflug imaging were included in the study. Vector analysis was performed to evaluate corneal astigmatism and Bland-Altman analysis was conducted to evaluate the limits of agreement of similar parameters among devices. Results: The mean TK was statistically significantly different from the keratometry obtained from optical biometers and values measured by the Scheimpflug imaging system. The magnitude of mean difference was greater between TK and TCP (0.75 ± 0.25) compared to other variables. The mean difference in astigmatism between TK, ss-OCT-K (0.09 ± 0.12, p = 0.48), OCLR-K (0.10 ± 0.48, p = 0.91), and TCP (0.09 ± 0.47, p = 0.31) was not statistically significant but was statistically significant between TK and SimK values (0.23D ± 0.49D). The axis of orientation (<20°) of astigmatism was comparable (100%, 28 eyes) between two keratometry variables measured by ss-OCT. Conclusion: There appears to be a greater correlation of automated keratometry, and TK values obtained from ss-OCT compared to other variables studied. The measurements from TK, Simk, and TCP cannot be used interchangeably.

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Refractive outcome and tomographic changes after Descemet membrane endothelial keratoplasty in pseudophakic eyes with Fuchs’ endothelial dystrophy

International Ophthalmology ◽

10.1007/s10792-021-01850-w ◽

2021 ◽

Author(s):

Bishr Agha ◽

Nura Ahmad ◽

Daniel G. Dawson ◽

Thomas Kohnen ◽

Ingo Schmack

Keyword(s):

Central Corneal Thickness ◽

Corneal Thickness ◽

Corneal Astigmatism ◽

Endothelial Keratoplasty ◽

Descemet Membrane Endothelial Keratoplasty ◽

Corneal Densitometry ◽

Scheimpflug Imaging ◽

Fuchs Endothelial Dystrophy ◽

Posterior Corneal Astigmatism

Abstract Purpose To analyze refractive and topographic changes secondary to Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic eyes with Fuchs’ endothelial dystrophy (FED). Methods Eighty-seven pseudophakic eyes of 74 patients who underwent subsequent DMEK surgery for corneal endothelial decompensation and associated visual impairment were included. Median post-operative follow-up time was 12 months (range: 3–26 months). Main outcome measures were pre- and post-operative manifest refraction, anterior and posterior corneal astigmatism, simulated keratometry (CASimK) and Q value obtained by Scheimpflug imaging. Secondary outcome measures included corrected distance visual acuity (CDVA), central corneal densitometry, central corneal thickness, corneal volume (CV), anterior chamber volume (ACV) and anterior chamber depth (ACD). Results After DMEK surgery, mean pre-operative spherical equivalent (± SD) changed from + 0.04 ± 1.73 D to + 0.37 ± 1.30 D post-operatively (p = 0.06). CDVA, proportion of emmetropic eyes, ACV and ACD increased significantly during follow-up. There was also a significant decrease in posterior corneal astigmatism, central corneal densitometry, central corneal thickness and corneal volume over time (p = 0.001). Only anterior corneal astigmatism and simulated keratometry (CASimK) remained fairly stable after DMEK. Conclusion Despite tendencies toward a hyperopic shift, changes in SE were not significant and refraction remained overall stable in pseudophakic patients undergoing DMEK for FED. Analysis of corneal parameters by Scheimpflug imaging mainly revealed changes in posterior corneal astigmatism pointing out the relevance of posterior corneal profile changes during edema resolution after DMEK.

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