Correlation of Anterior Segment Parameters in Keratoconus Patients

Torquetti, Leonardo; Ferrara, Guilherme; Ferrara, Paulo; Barbara, Adel

doi:10.5005/jp-journals-10025-1017

Cited by 3 publications

(4 citation statements)

References 20 publications

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“…Corneal front and back surface elevations are well-correlated with severity of the disease 39 and thinnest corneal thickness was inversely correlated with K readings. 40 In the present study, we found a strong correlation between the deviation of front and back elevations (Belin-Ambrosio Enhanced Ectasia Display) with DCVA  = 0.648 (p < 0.001) and  = 0.633 (p < 0.001) respectively. The front and back elevations at the apex using the 8 mm best-fit sphere was also strong correlated with DCVA  = 0.570 (p < 0.001) and  = 0.591 (p < 0.001) respectively.…”

Section: Discussionsupporting

confidence: 59%

Correlation of Topometric and Tomographic Indices with Visual Acuity in Patients with Keratoconus

Ramos¹,

Lopes²,

Faria-Correia³

et al. 2012

International Journal of Keratoconus and Ectatic Corneal Diseases

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Purpose To evaluate the correlations of Pentacam keratometric, topometric (derived from front surface curvature) and tomographic (derived from 3D corneal shape analysis) indices with best corrected visual acuity in patients with keratoconus. Materials and methods One eye randomly selected of 123 patients with bilateral keratoconus was retrospectively enrolled. All patients underwent a comprehensive ophthalmic examination including subjective refraction, distance best-spectacle corrected visual acuity (DCVA) measurement, and rotating Scheimpflug corneal tomography (Pentacam HR; Oculus, Wetzlar, Germany) at the same office visit. The correlations between the logarithm of the minimum angle of resolution (LogMAR) of DCVA and keratometric indices, topometric indices and tomographic indices were tested with nonparametric Spearman correlation coefficients (?). Results The mean LogMAR DCVA was 0.32 (~20/42) ±0.27 [range: −0.10 (20/15) to 1.30 (20/400)]. There were strong correlations between DCVA and many keratometric, topometric and tomographic indices. A strong positive correlation was found between DCVA and BAD-Df (ρ = 0.648, p < 0.001), BAD-Db (ρ = 0.633, p < 0.001), K2 (ρ = 0.643, p < 0.001), Kmax (ρ = 0.608, p < 0.001), TKC (ρ = 0.558, p < 0.001), BAD-D (ρ = 0.577, p < 0.001), ISV (ρ = 0.573, p < 0.001), CKI (ρ = 0.530, p < 0.001), KI (ρ = 0.531, p < 0.001). A strong negative correlation was seen between DCVA and Asph Q front 30° (ρ = −0.521, p < 0.001). Conclusion There are significant correlations between visual acuity and Pentacam parameters. Such parameters may be considered for improving staging of the disease, as well as for monitoring progression or treatment as outcome measures. There is a potential for combining parameters to enhance the correlations. How to cite this article Lopes BT, Ramos IC, Faria-Correia F, Luz A, de Freitas Valbon B, Belin MW, Ambrósio R Jr. Correlation of Topometric and Tomographic Indices with Visual Acuity in Patients with Keratoconus. Int J Kerat Ect Cor Dis 2012;1(3):167-172.

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Section: Discussionsupporting

confidence: 59%

Correlation of Topometric and Tomographic Indices with Visual Acuity in Patients with Keratoconus

Ramos¹,

Lopes²,

Faria-Correia³

et al. 2012

International Journal of Keratoconus and Ectatic Corneal Diseases

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“…12 However, most published papers found no significant differences in CV among different grades of keratoconus. 13,17 Mannion et al have found that CV was significantly decreased in keratoconus, particularly in the central and paracentral area explained by loss of corneal tissue. The reduction in CV was in moderate and severe cases of keratoconus, but not in the early cases.…”

Section: Discussionmentioning

confidence: 99%

“…The Q-value has been used as an important parameter for ICRS selection. 16,17 A recently published paper has shown how much each thickness of ICRS (single or paired) can change the cornea asphericity. 10 Based on this data we can expect the asphericity change based on the thickness of the segment implanted.…”

Section: Discussionmentioning

confidence: 99%

The Influence of Corneal Volume in Surgical Planning: Insights for a New Parameter for the Ferrara Ring Nomogram

Torquetti¹,

Dias²

2013

International Journal of Keratoconus and Ectatic Corneal Diseases

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Purpose: To evaluate the corneal volume (CV) before and after Ferrara intrastromal corneal ring segments (ICRS) implantation and its influence in clinical outcomes in keratoconus patients. Materials and methods:A total of 77 eyes of 42 keratoconus patients consecutively implanted with the Ferrara ICRS were evaluated with a Pentacam (Oculus Optikgerate GmbH). The following parameters were obtained: Anterior corneal asphericity (Q), CV and thinnest corneal thickness (TCT). The inter-relation between Q and CV was evaluated. Results:In patients with CV inside two standard deviation (SD: 53.51-60.65) of the mean CV, the postoperative asphericity values roughly agreed with expected asphericity values. In patients with CV outside two SD intervals (<53.51 and >60.65) of the mean CV, the postoperative asphericity values did not agreed with expected asphericity values. Corneas with high volumes (>60.65) had less change of asphericity than corneas with low volumes. Conclusion:The CV is a new parameter, to be better studied, as it seems to be important in ICRS selection. Corneas with high volumes may require more tissue to get flattened and properly reshaped.

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“…The cornea has a steeper curvature in its centre than in its periphery, and normal corneas have a mean Q‐value (a coefficient of corneal asphericity) of −0.26 ± 0.18 and a range of −0.88 to +0.50 (Kiely et al 1982 ; Safarzadeh & Nasiri 2016 ). There is an inverse relationship between keratoconus severity and the Q‐value, due to increased prolateness; however, this relationship is lost in advanced keratoconus, as it becomes difficult to obtain a reliable Q‐value (Torquetti et al 2012 ).…”

Section: Introductionmentioning

confidence: 99%

A novel Q‐value‐based nomogram for single intracorneal ring segment implantation versus standard manufacturer's nomogram combined with accelerated cross‐linking for treatment of keratoconus: a randomized controlled trial

Iqbal

Elmassry

Mounir

et al. 2020

Acta Ophthalmologica

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Purpose To compare the efficacy of implanting a single Keraring segment according to a novel Q‐value‐based nomogram (QN) to that of segment implantation according to the manufacturer's standard nomogram (SN), for keratoconus treatment. Methods This was a prospective, randomized controlled trial of 104 patients (104 eyes) with Amsler‐Krumeich grade 1 or 2 keratoconus, and type 1 or 2 cone asymmetry determined according to manufacturer's classification. They were randomly distributed into two groups: group A patients (n = 52) underwent Keraring implantation according to the SN, and group B patients (n = 52) underwent implantation of a single (210° arc‐length) Keraring segment according to the QN. Both treatments were combined with accelerated transepithelial cross‐linking, and follow‐up was 6 months. Main outcome measures were preoperative and postoperative visual acuity, subjective refraction and corneal topography. Results At postoperative month 6, group B exhibited statistically significantly higher values of mean uncorrected distance visual acuity (UDVA), sphere, K2, K‐average, K‐max and Q‐anterior (p = 0.02, 0.01, 0.002, 0.001, 0.0001 and 0.03, respectively) compared to that of group A. However, group A exhibited better refractive cylindrical improvements (p = 0.04). In group A, we documented spontaneous extrusion of one Keraring segment. Conclusion Single 210° arc‐length segment implantation using our objective QN was more efficacious for keratoconus treatment than using the subjective SN. The nomograms were comparable when the Q‐anterior value was >−1.00; however, the QN was superior to the SN when the Q‐anterior value was ≤−1.00. The QN yielded greater postoperative UDVA and smoother corneal remodelling than did the SN for treatment of grade 1 and 2 keratoconic eyes.

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Correlation of Anterior Segment Parameters in Keratoconus Patients

Cited by 3 publications

References 20 publications

Correlation of Topometric and Tomographic Indices with Visual Acuity in Patients with Keratoconus

Correlation of Topometric and Tomographic Indices with Visual Acuity in Patients with Keratoconus

The Influence of Corneal Volume in Surgical Planning: Insights for a New Parameter for the Ferrara Ring Nomogram

A novel Q‐value‐based nomogram for single intracorneal ring segment implantation versus standard manufacturer's nomogram combined with accelerated cross‐linking for treatment of keratoconus: a randomized controlled trial

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