Computational Models for Optimization of the Intrastromal Corneal Ring Choice in Patients With Keratoconus Using Corneal Tomography Data

Importance: This study shows that a newer long-arc length intrastromal corneal ring segment is efficient and safe for keratoconus treatment. Background: To evaluate visual, tomographic results and complications of a 320-degree intrastromal corneal ring segment implantation with the femtosecond laser for keratoconus treatment. Design: A prospective, nonrandomized, and interventional study. Participants: A total of 34 eyes of 31 patients diagnosed with keratoconus were enrolled. Methods: Patients were divided into two groups based on the strategy used for 320-degree intrastromal corneal ring segment thickness selection. In one group, this selection was based on spherical equivalent (SE group) and in the other on the mean asphericity (Q group). The uncorrected and corrected distance visual acuities, spherical equivalent, K1, K2, Km, Kmax, and mean asphericity ( Q) on corneal tomography were evaluated preoperatively and at 3 and 6 months postoperatively. For astigmatism improvement, we analyzed the corneal tomographic vectorial astigmatism change preoperatively and at 6 months postoperatively. The mean follow-up period was 6.63 ± 0.96 months. Results: The mean uncorrected distance visual acuity and corrected distance visual acuity improved with a significant spherical equivalent improvement ( p < 0.05), with no differences between the 320-degree intrastromal corneal ring segment groups. All corneal tomographic parameters improved significantly ( p < 0.05) between the preoperative and postoperative intervals, with a significant better performance when we used spherical equivalent for the 320-degree intrastromal corneal ring segment thickness selection. Finally, the mean vectorial corneal tomographic astigmatism significantly improved after 6 months, again with no differences between groups. Conclusion: This study suggests that implanting a 320-degree intrastromal corneal ring segment is a safe and effective procedure for treating patients with keratoconus. It also suggests that for thickness selection spherical equivalent is the better strategy.

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Differentiation of mild keratoconus from corneal warpage according to topographic inferior steepening based on corneal tomography data

Arquivos Brasileiros de Oftalmologia ◽

10.5935/0004-2749.20160075 ◽

2016 ◽

Vol 79 (4) ◽

pp. 264-267 ◽

Cited By ~ 2

Author(s):

Lia Florim Patrão ◽

Ana Laura Caiado Canedo ◽

João Luiz Peixoto Braga de Azevedo ◽

Rosane Correa ◽

Renato Ambrósio Jr.

Keyword(s):

Tomography Data ◽

Corneal Tomography

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Subclinical Keratoconus Detection in Identical Twins

International Journal of Keratoconus and Ectatic Corneal Diseases ◽

10.5005/jp-journals-10025-1119 ◽

2016 ◽

Vol 5 (1) ◽

pp. 35-39 ◽

Cited By ~ 4

Author(s):

Isaac Ramos ◽

Gustavo Guerra ◽

Vitor Buchmuller de Oliveira ◽

Ivan Ferreira

Keyword(s):

Front Surface ◽

Identical Twins ◽

Subclinical Disease ◽

Corneal Nerves ◽

Classification Pattern ◽

The Right ◽

The Impact ◽

Tomography Data ◽

Corneal Tomography ◽

Fellow Eyes

ABSTRACT Purpose To report clinical keratoconus in only one eye of two identical female twins, along with subclinical disease in the fellow eyes, elaborating on the two-hit hypothesis of ectasia development, which relates to the combination of genetics and the impact of environment. Methods Case report and literature review. Results Two identical 48-year-old female twins were presented for clinical evaluation. Mild keratoconus was detected in the right eye of twin 1, characterized by classic slit-lamp findings (exacerbated corneal nerves and incomplete Fleisher's ring) and front surface curvature abnormalities, including asymmetry of the inferior–superior curvature at 6 mm (I–S value) of 2.78 D and a grade 1 Topographic Keratoconus Classification pattern. Topographic Keratoconus Classification was possible in the fellow eye of twin 1 (I–S value = 1.22 D) and negative in both eyes of twin 2 (I–S value = −0.46 OD and −0.13 OS). Ambrósio's Relational Thickness for the maximal progression meridian was 209 and 354 in twin 1 and 360 and 392 in twin 2 in the right and left eyes respectively. The final deviation value of the Belin–Ambrósio Enhanced Ectasia Display was 4.54 and 1.47 in twin 1 and 1.7 and 1.35 in twin 2. Conclusion Corneal tomography data provide a better representation of corneal genotype in detecting mild, subclinical, or forme fruste keratoconus in the fellow eyes with normal topography of these twins. These cases present high risk or susceptibility for ectasia progression if environmental factors are associated (second hit). How to cite this article Guerra G, de Oliveira VB, Ferreira I, Ramos I, Belin MW, Ambrósio R Jr. Subclinical Keratoconus Detection in Identical Twins. Int J Kerat Ect Cor Dis 2016;5(1):35-39.

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Ferrara Rings for Visual Rehabilitation in Eyes with Keratoconus and Previous Cross-Linking Using the Ferrara Ring Nomogram

Vision ◽

10.3390/vision5040045 ◽

2021 ◽

Vol 5 (4) ◽

pp. 45

Author(s):

Cameron A. McLintock ◽

James McKelvie ◽

Ye Li ◽

Samer Hamada ◽

Damian Lake

Keyword(s):

Visual Acuity ◽

Case Series ◽

Cross Linking ◽

Visual Rehabilitation ◽

Queen Victoria ◽

Intrastromal Corneal Ring ◽

Uncorrected Visual Acuity ◽

History Of ◽

Corneal Collagen ◽

Corneal Tomography

Purpose: To report the visual, refractive and tomographic outcomes following the implantation of intrastromal corneal ring segments (ICRS) (Ferrara rings, AJL Ophthalmics, Miñano, Spain) in eyes with a history of keratoconus and corneal cross-linking using the Ferrara ring nomogram. Methods: Retrospective, interventional case series performed at the Corneoplastics Unit, Queen Victoria Hospital, East Grinstead, United Kingdom. Results: 21 eyes of 19 patients with a history of keratoconus and prior corneal collagen cross-linking had Ferrara Intrastromal Corneal Ring Segments implanted between December 2015 and October 2017. The number, thickness and length of ring segments was chosen based on the Ferrara ring company nomogram. Mean uncorrected visual acuity (UDVA) improved from 0.88 to 0.52 logMAR (p < 0.001). Mean corrected visual acuity (CDVA) improved from 0.47 to 0.36 logMAR (p = 0.046). The percentage of eyes achieving 20/40 UDVA and CDVA increased from 5% to 38% and from 38% to 67%, respectively. Of the eyes, 52.3% gained at least two lines of CDVA. The spherical equivalent improved from −7.51D to −3.76D (p < 0.001) and the refractive astigmatism magnitude improved from 5.14D to 2.76D (p = 0.004). There were significant improvements in the corneal tomography with mean keratometry (KM) improving from 50.40D (3.53) to 48.24D (3.00) (p = 0.01) and keratometric astigmatism magnitude improving from 5.14D (2.91) to 2.76D (1.67) (p = 0.004). Conclusion: Insertion of Ferrara rings in keratoconic eyes with a history of prior cross-linking using the company nomogram results in significant improvements in visual, refractive and tomographic outcomes.

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Computational Models for Turbulent Reacting Flows

10.1017/cbo9780511610103 ◽

2003 ◽

Cited By ~ 368

Author(s):

Rodney O. Fox

Keyword(s):

Computational Models ◽

Reacting Flows ◽

Turbulent Reacting Flows

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Sequential Difficulty Effects During Strategy Execution

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1027/1618-3169/a000157 ◽

2012 ◽

Vol 59 (5) ◽

pp. 295-301 ◽

Cited By ~ 35

Author(s):

Kim Uittenhove ◽

Patrick Lemaire

Keyword(s):

Computational Models ◽

Preceding Trial ◽

Human Cognition ◽

Strategy Execution ◽

Strategy Performance ◽

Empirical Implications

In two experiments, we tested the hypothesis that strategy performance on a given trial is influenced by the difficulty of the strategy executed on the immediately preceding trial, an effect that we call strategy sequential difficulty effect. Participants’ task was to provide approximate sums to two-digit addition problems by using cued rounding strategies. Results showed that performance was poorer after a difficult strategy than after an easy strategy. Our results have important theoretical and empirical implications for computational models of strategy choices and for furthering our understanding of strategic variations in arithmetic as well as in human cognition in general.

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Does Viotin Activate Violin More Than Viocin?

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1027/1618-3169/a000223 ◽

2014 ◽

Vol 61 (1) ◽

pp. 23-29 ◽

Cited By ~ 15

Author(s):

Manuel Perea ◽

Victoria Panadero

Keyword(s):

Word Recognition ◽

Visual Word Recognition ◽

Developmental Dyslexia ◽

Computational Models ◽

Error Rates ◽

Visual Word ◽

Base Word ◽

Similar Response ◽

Skilled Readers ◽

Young Readers

The vast majority of neural and computational models of visual-word recognition assume that lexical access is achieved via the activation of abstract letter identities. Thus, a word’s overall shape should play no role in this process. In the present lexical decision experiment, we compared word-like pseudowords like viotín (same shape as its base word: violín) vs. viocín (different shape) in mature (college-aged skilled readers), immature (normally reading children), and immature/impaired (young readers with developmental dyslexia) word-recognition systems. Results revealed similar response times (and error rates) to consistent-shape and inconsistent-shape pseudowords for both adult skilled readers and normally reading children – this is consistent with current models of visual-word recognition. In contrast, young readers with developmental dyslexia made significantly more errors to viotín-like pseudowords than to viocín-like pseudowords. Thus, unlike normally reading children, young readers with developmental dyslexia are sensitive to a word’s visual cues, presumably because of poor letter representations.

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