Total corneal refractive power and shape in Down syndrome

Asgari, Soheila; Mehravaran, Shiva; Fotouhi, Akbar; Makateb, Ali; Hashemi, Hassan

doi:10.1177/1120672119883594

Cited by 13 publications

(14 citation statements)

References 42 publications

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“…In this study, however, these indices were poor and very poor in detecting KCS in DS patients. In the sample population of our study, central-peripheral keratometric indices indicated steeper corneas in DS-C cases compared to the NC group [29]. This difference significantly reduces the diagnostic power of these indices, especially Kmax, for milder cases.…”

Section: Discussionmentioning

confidence: 54%

Tomography-based definition of keratoconus for Down syndrome patients

et al. 2020

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Background To assess the diagnostic ability of Pentacam HR (Oculus Optikgeräte, GmbH, Wetzlar, Germany) tomographic indices in discriminating keratoconus (KC) and KC suspect (KCS) in 10- to 30-year-old patients with Down syndrome (DS). Methods In this study, DS patients were enrolled through special needs schools, the National Down Syndrome Society, and relevant non-profit organizations. Diagnoses were made independently by two experienced specialists. Forty Pentacam indices related to corneal thickness, volume, density, keratometry, power, shape, aberration, and elevation were extracted. For each index, the accuracy for KC and KCS diagnosis was evaluated using discriminant analysis and the area under receiver operating characteristic curve (AUROC). From each enrolled case, data from only one eye was entered in the analyses. Results Analyses were performed on data from 25 KC, 46 KCS, and 154 non-ectatic DS eyes. The best discriminants for KC were anterior higher order aberrations (HOA) (cutoff > 0.643, AUROC = 0.879), posterior vertical coma (cutoff > 0.0702 μm, AUROC = 0.875), anterior vertical coma (cutoff > 0.4124 μm, AUROC = 0.868), and total HOA (cutoff > 0.608, AUROC = 0.867). The difference between AUROCs were not statistically significant (all P > 0.05). For KCS, the best discriminants were minimum corneal thickness (cutoff ≤ 480.0 μm, AUROC = 0.775), corneal volume (cutoff ≤ 55.3 μm, AUROC = 0.727) and Belin Ambrosio display-total deviation (BAD-D) (cutoff > 2.23, AUROC = 0.718) with no significant difference between AUROCs (all P > 0.05). Conclusions In this sample of DS patients, best KC discriminators were HOA and coma which showed good diagnostic ability. For KCS, best predictors were minimum corneal thickness, corneal volume, and BAD-D with relatively good diagnostic ability. Defining a new set of KC diagnostic criteria for DS patients is suggested.

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Section: Discussionmentioning

confidence: 54%

Tomography-based definition of keratoconus for Down syndrome patients

et al. 2020

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“…Several studies have suggested that patients with DS had steeper, thinner and more irregular corneas than those from non-DS controls, even though these findings did not fulfil the criteria for KC diagnosis [ 5 , 10 , 11 , 12 , 13 , 14 ]. However, Alio and co-workers [ 5 ] were the first to describe the high frequency of abnormal topographical findings in patients with DS.…”

Section: Introductionmentioning

confidence: 99%

Evidence of a Down Syndrome Keratopathy: A Three-Dimensional (3-D) Morphogeometric and Volumetric Analysis

Toprak

Vega

Cavas

et al. 2021

JPM

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The aim of this study was to investigate whether a different and abnormal corneal profile is present in Down syndrome (DS) by personalized three-dimensional (3D) modelling. This single-centre cross-sectional study included 43 patients with DS (43 eyes) and 58 age-sex-matched control subjects (58 eyes) with normal karyotype and topography. Refraction, central corneal thickness (CCT), aberrations (high-order, coma and spherical), asphericity and morphogeometric/volumetric parameters based on a 3D corneal model that was generated from raw topographical data were evaluated. Deviation of anterior/posterior apex (Dapexant/Dapexpost) and thinnest point (Dmctant/Dmctpost) from corneal vertex, anterior/posterior surface area (Aant/Apost), sagittal area passing through the anterior/posterior apex (Aapexant/Aapexpost) and thinnest point (Amctpost), total corneal volume (Vtotal) and volumetric progression for each 0.05 mm step of the radius value centred to the thinnest point (VOLMCT) and anterior/posterior apex (VOLAAP/VOLPAP) comprised the morphogeometric/volumetric parameters. In the DS group, 58.1% of the eyes presented abnormal topography. High-order and coma aberrations, asphericity, Dapexant, Aant, Apost and Aapexant were significantly higher, whereas CCT, Aapexpost, Amctpost, Vtotal, VOLAAP, VOLPAP and VOLMCT were lower in the DS group than in the control group (p < 0.05). Dapexpost did not differ between the groups (p > 0.05). This study demonstrates that corneas of the subjects with DS are different and more aberrated than those of normal age- and sex-matched non-DS controls. Anterior corneal apex appears to be displaced in DS even with normal topography, while posterior apex seems stable although topography is abnormal. These findings may help to modify our approach in the diagnosis of keratopathy in subjects with DS.

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“…The cornea in patients with DS has a different structure than that in persons without DS, and even in the absence of pathologies, it can be thinner and steeper [14]. The reported prevalence of KC is also higher in these patients compared to normal subjects [1].…”

Section: Discussionmentioning

confidence: 90%

Accelerated and Standard Corneal Cross-Linking Protocols in Patients with Down Syndrome: A Non-inferiority Contralateral Randomized Trial

et al. 2020

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Introduction To compare the results of an accelerated corneal cross-linking (CXL) protocol (9 mW/cm 2 , 10 min) with the standard CXL protocol (3 mW/cm 2 , 30 min) in patients with Down syndrome (DS) who have keratoconus (KC). Methods Twenty-seven 10- to 20-year-old patients with DS who had bilateral progressive KC were enrolled in a contralateral randomized trial and completed 2 years of follow-up examinations. Fellow eyes were randomly allocated to the accelerated CXL group or the standard CXL group. The main outcome measure was change in maximum keratometry (K max ) centered on the steepest point (zonal K max − 3 mm) with a non-inferiority margin of 1.0 diopter (D). Vision and refraction tests, ophthalmic examinations, and corneal tomography were performed at baseline and at 6, 12, and 24 months after CXL. Failure was defined as an increase of ≥ 1.0 D in zonal K max − 3 mm within a 12-month period. Results The mean age (± standard deviation) of the patients was 15.71 ± 2.40 years. The within-group change in zonal K max − 3 mm was not significant after 2 years in either group, and within-group zonal K max − 3 mm remained stable. At 2 years after CXL, the mean change in the zonal K max − 3 mm was – 0.02 ± 0.81 D and – 0.31 ± 0.86 D in the accelerated CXL and standard CXL groups, respectively ( P = 0.088). At 1 year of follow-up, three patients in the accelerated CXL group showed treatment failure (mean change in zonal K max − 3 mm + 2.12 ± 0.11 D); no patients in the standard CXL group showed treatment failure. At 2 years of follow-up, these three patients showed a decrease of – 0.43 ± 0.18 D in zonal K max − 3 mm from a baseline value of 55.11 ± 0.32 D. The 2-year trends of the inferior–superior asymmetry and vertical coma were statistically significantly different between the two groups, with the accelerated CXL protocol showing superiority in patients with higher baseline values. Conclusion In young patients with Down syndrome, the accelerated CXL protocol was able to halt disease progression and may be an alternative for the standard CXL protocol. In advanced KC, the efficacy of the accelerated approach was delayed and appeared later in the follow-up. In asymmetric cornea, the accelerated CXL resulted in centralization of the corneal cone. Trial Registration Iranian Registry of Clinical Trials, IRCT20100706004333N3 Electronic supplementary material The online version of this article (10.1007/s40123-020-00303-4) contains supplementary material, which is available to authorized users.

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Total corneal refractive power and shape in Down syndrome

Cited by 13 publications

References 42 publications

Tomography-based definition of keratoconus for Down syndrome patients

Tomography-based definition of keratoconus for Down syndrome patients

Evidence of a Down Syndrome Keratopathy: A Three-Dimensional (3-D) Morphogeometric and Volumetric Analysis

Accelerated and Standard Corneal Cross-Linking Protocols in Patients with Down Syndrome: A Non-inferiority Contralateral Randomized Trial

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