Corneal Thickness Profile and Posterior Corneal Astigmatism in Normal Corneas

Ueno, Yuta; Hiraoka, Takahiro; Miyazaki, Maki; Ito, Mutsuko; Oshika, Tetsuro

doi:10.1016/j.ophtha.2015.01.021

Cited by 46 publications

(38 citation statements)

References 29 publications

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“…The changes of corneal thickness by age were still unclear in human and animals. Previous studies reported that there was no significant change in the corneal thickness over time [ 29 , 30 ] and the others showed the decreased trend of corneal thickness by age [ 31 , 32 ]. However, those studies did not adjust the measured thicknesses by study subjects’ body sizes (weights), which is what we performed in our study ( Fig 2 ).…”

Section: Discussionmentioning

confidence: 99%

Scaling and maintenance of corneal thickness during aging

et al. 2017

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Corneal thickness is tightly regulated by its boundary endothelial and epithelial layers. The regulated set-point of corneal thickness likely shows inter-individual variations, changes by age, and response to stress. Using anterior segment-optical coherence tomography, we measure murine central corneal thickness and report on body size scaling of murine central corneal thickness during aging. For aged-matched mice, we find that corneal thickness depends on sex and strain. To shed mechanistic insights into these anatomical changes, we measure epithelial layer integrity and endothelial cell density during the life span of the mice using corneal fluorescein staining and in vivo confocal microscopy, respectively and compare their trends with that of the corneal thickness. Cornea thickness increases initially (1 month: 114.7 ± 3.0 μm, 6 months: 126.3 ± 1.6 μm), reaches a maximum (9 months: 129.3 ± 4.4 μm) and then reduces (12 months: 127 ± 2.9 μm, 13 months: 119.5 ± 7.6 μm, 14 months: 110.6 ± 10.6 μm), while the body size (weight) increases with age. We find that endothelial cell density reduces from 2 months old to 8 months old as the mice age and epithelial layer accumulates damages within this time frame. Finally, we compare murine corneal thickness with those of several other mammals including humans and show that corneal thickness has an allometric scaling with body size. Our results have relevance for organ size regulation, translational pharmacology, and veterinary medicine.

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Section: Discussionmentioning

confidence: 99%

Scaling and maintenance of corneal thickness during aging

et al. 2017

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“…Therefore, in eyes with with-the-rule astigmatism, keratometric astigmatism overestimates total corneal astigmatism, whereas in eyes with against-the-rule astigmatism, keratometric astigmatism underestimates total corneal astigmatism [4, 7, 10]. These discrepancies seem to be explained by the fact that corneal thickness profile is not uniform between horizontal and vertical directions, i.e., the cornea is thicker in the vertical than the horizontal directions [11]. Thus, it is not always true that the anterior and posterior corneal curvatures have a constant and linear relationship [9, 11], and posterior corneal astigmatism should be at least partially responsible for postoperative refractive astigmatism of unknown origin [2, 3].…”

Section: Introductionmentioning

confidence: 99%

“…These discrepancies seem to be explained by the fact that corneal thickness profile is not uniform between horizontal and vertical directions, i.e., the cornea is thicker in the vertical than the horizontal directions [11]. Thus, it is not always true that the anterior and posterior corneal curvatures have a constant and linear relationship [9, 11], and posterior corneal astigmatism should be at least partially responsible for postoperative refractive astigmatism of unknown origin [2, 3]. …”

Section: Introductionmentioning

confidence: 99%

Influence of posterior corneal astigmatism on postoperative refractive astigmatism in pseudophakic eyes after cataract surgery

et al. 2016

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BackgroundTo examine the influence of posterior corneal astigmatism on postoperative refractive astigmatism in pseudophakic eyes after cataract surgery.MethodsThe study enrolled 64 pseudophakic eyes of 50 patients (71.8 ± 9.9 years old, mean ± standard deviation) who had undergone phacoemulsification with non-toric IOL implantation. Refractive astigmatism was measured using an auto ref-keratometer with a 0.01- diopter (D) scale. Two types of corneal astigmatism were calculated using anterior segment optical coherence tomography; keratometric and total corneal astigmatism. Keratometric astigmatism was obtained based on anterior corneal curvature alone and total corneal astigmatism was calculated using both anterior and posterior corneal curvatures. The difference between refractive and corneal astigmatism was computed as the vector difference using 1) refractive and keratometric astigmatism and 2) refractive and total corneal astigmatism.ResultsThe mean refractive, keratometric, and total corneal astigmatism was 0.92 ± 0.48 D, 0.87 ± 0.44 D, and 0.94 ± 0.46 D, respectively. The difference between refractive and keratometric astigmatism (0.70 ± 0.40 D, mean vector of 0.30 D axis 164°) was significantly larger than the difference between refractive and total corneal astigmatism (0.63 ± 0.38 D, mean vector of 0.12 D axis 137°) (P = .019).ConclusionsThe difference between refractive and total corneal astigmatism, calculated using both anterior and posterior corneal curvatures, was significantly smaller than the difference between refractive and keratometric astigmatism using anterior corneal astigmatism alone, implying that the latter overestimates the true postoperative refractive astigmatism and can cause cylindrical inaccuracy after cataract surgery.

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“…The real TCA can be calculated from 3-dimensional anterior segment optical coherence tomography [ 18 ] and Scheimpflug corneal topography [ 7 10 ]. The calculation using these devices would more predictable than that using ACA only [ 10 19 ].…”

Section: Discussionmentioning

confidence: 99%

Improving the Toric Intraocular Lens Calculation by Considering Posterior Corneal Astigmatism and Surgically-induced Corneal Astigmatism

Yoon

Kim

2018

Korean J Ophthalmol

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PurposeTo investigate the effect of surgically induced corneal astigmatism (SICA) and total corneal astigmatism (TCA) estimation on the anterior corneal astigmatism (ACA)-based toric intraocular lens (IOL) calculation.MethodsData from preoperative and postoperative corneal astigmatism, postoperative visual acuities, and refractive outcomes were collected. The incision was superior in with the rule anterior corneal astigmatism (WTRA) eyes and temporal in against the rule anterior corneal astigmatism eyes. The following five methods of calculating the toric IOL were compared: (1) ACA only and estimated SICA; (2) ACA with a fixed posterior corneal astigmatism (PCA) and estimated SICA; (3) ACA with a fixed PCA value and actual SICA; (4) and (5) TCA derived from the regression equations of ACA and actual SICA. The residual astigmatism was simulated. The Alpins method was used to analyze the astigmatism.ResultsSixty eyes from 46 patients were enrolled. Thirty eyes had WTRA and the other thirty had against the rule anterior corneal astigmatism. The vector and arithmetic means of the difference vector decreased when the information regarding the actual SICA and PCA was added to the calculation (from 0.59 diopters [D] @ 87.5° to 0.15 D @ 48.5°, and from 0.95 ± 0.53 to 0.71 ± 0.63 D, respectively; p < 0.001). The mean difference vector across the whole sample was lowest using model 5. The correction index was significantly closest to 1.0 in the WTRA group.ConclusionsResearchers may improve the accuracy of post-implantation predictions by calculating toric IOL using exact SICA and TCA, with consideration of the PCA derived from the regression equation of ACA.

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Corneal Thickness Profile and Posterior Corneal Astigmatism in Normal Corneas

Cited by 46 publications

References 29 publications

Scaling and maintenance of corneal thickness during aging

Scaling and maintenance of corneal thickness during aging

Influence of posterior corneal astigmatism on postoperative refractive astigmatism in pseudophakic eyes after cataract surgery

Improving the Toric Intraocular Lens Calculation by Considering Posterior Corneal Astigmatism and Surgically-induced Corneal Astigmatism

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