Effects of Preoperative Topometric Indices on Visual Gain After Intracorneal Ring Segment Implantation For Keratoconus

Utine, Canan Aslı; Engin, Ceren Durmaz; Ayhan, Zi̇ya

doi:10.1097/icl.0000000000000490

Cited by 8 publications

(9 citation statements)

References 9 publications

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“…It is less likely to achieve significant visual gain in advanced keratoconus which has lower postoperative predictability [5]. We have also previously reported that the expected visual improvement decreases significantly when preoperative SimK avg is > 55 D [9]. On the other hand, success of ICRS implantation seem to be closely related to the degree of preoperative visual limitation.…”

Section: Discussionmentioning

confidence: 84%

“…We have previously shown that ICRS implantation seems to approximate the anterior corneal asphericity of "advanced prolate" shape to "the optimal prolate" Q value of −0.52 and "spherical aberration-free" human corneal Q value of −0.46 [4]. We also suggested that the preoperative index of surface variance (ISV) value seems to be beneficial in predicting visual gain after ring surgery in addition to SimK avg [9]. In this study, Group 2 had initially higher CKI values, indicating a more severe stage of keratoconus; and this difference persisted postoperatively (Table 1).…”

Section: Discussionmentioning

confidence: 99%

“…KeraRing (Mediphacos, Brazil) segments are ring segments made of polymethyl-methacrylate with a triangular transverse section, optical zone of 5.0 mm, inner and outer diameters of 5.40 mm and 6.60 mm, respectively, base width of 800 μm, thicknesses of 150-300 μm with 50 μm increments and arc lengths of 90°-210°. Selection of ICRS parameters was made as per the KeraRing 2009 nomogram [9] based on visual, refractive and topographic parameters. The number of ring segments were determined according to the distribution of ectatic area on the corneal surface, whereas the thickness and arc lengths of the ring segments were determined according to the spherocylindrical refraction and CDVA.…”

Section: Surgical Techniquementioning

confidence: 99%

“…Location of the cone was defined as described in the nomogram [9]. As CDVA was ≤ 0.3 in all cases, treatment was planned on the keratometric values and steep axis.…”

Section: Surgical Techniquementioning

confidence: 99%

“…A reference line was drawn along the steep meridian on the sagittal topography map. Corneal asymmetry type was determined by studying the steep area on each side of the reference meridian [9]. If the line separated the steep area into two equal parts, cone location was said to be "central".…”

Section: Surgical Techniquementioning

confidence: 99%

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The number of intracorneal ring segments in asymmetric and central cones

et al. 2021

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Background To compare the results of single versus double intracorneal ring segment (ICRS) (KeraRing) implantation in keratoconus with respect to different cone locations. Methods Twenty-two eyes of 18 patients with totally asymmetric cones (20–80% or 0–100% distribution along steep axis) were implanted with single ICRS (Group 1), 38 eyes of 32 patients with central or partially asymmetric cones (50–50% or 40–60% distribution along steep axis) were implanted with double ICRS (Group 2), at a depth of 80% of the site of implantation, in channels created with femtosecond laser device. All patients had uncorrected and corrected distance visual acuities (UDVA and CDVA, respectively) of ≤ 0.3 Snellen lines. Results In both groups, patients had median UDVA and CDVA gain of 3 Snellen lines (P > 0.05). Postoperative improvement in indices of vertical asymmetry and height decentration in Group 1; simulated keratometry, corneal astigmatism and anterior corneal asphericity values in Group 2 were greater (P < 0.05). A total of 10 eyes (45.5%) in Group 1 were recommended double ring implantation by the manufacturer’s nomogram, but underwent single ICRS implantation and achieved visual, refractive, tomographic outcomes comparable to that in Group 2, although corneal cylindrical correction was less and final topographic astigmatism was greater. Conclusion Double ICRS implantation seems to be superior in terms of keratometry, corneal astigmatism and anterior corneal asphericity improvement. Single ICRS implantation in totally asymmetric cones seems to provide satisfactory visual, refractive and tomographic results, similar to double ICRS implantation in central and partially asymmetric cones, by inducing central shift of the cone.

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Surgical Techniquementioning

confidence: 99%

“…Location of the cone was defined as described in the nomogram [9]. As CDVA was ≤ 0.3 in all cases, treatment was planned on the keratometric values and steep axis.…”

Section: Surgical Techniquementioning

confidence: 99%

Section: Surgical Techniquementioning

confidence: 99%

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The number of intracorneal ring segments in asymmetric and central cones

et al. 2021

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The Characteristics of Quick Contrast Sensitivity Function in Keratoconus and Its Correlation with Corneal Topography

Xian

Zhang

et al. 2022

Ophthalmol Ther

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Introduction: To characterize quick contrast sensitivity function (qCSF) in keratoconus and its correlation with corneal topographic parameters. Methods: Patients with keratoconus (n = 120) who visited the Fudan Eye and ENT Hospital between April and June 2021 were enrolled in our study. A total of 215 eyes were subdivided into three groups according to maximum keratometry (K max ): Group 1 (K max B 48 D, 74 eyes), Group 2 (48 D \ K max B 55 D, 64 eyes), and Group 3 (K max [ 55 D, 77 eyes). Manifest refraction, best corrected distance visual acuity (BCVA), corneal topography, and the qCSF test were examined. Intergroup comparisons and correlations among various corneal topographic parameters and qCSF were analyzed. Results: Significant differences in the area under the log CSF (AULCSF) and CSF Acuity among the three groups were found, which decreased with an increase in K max . Contrast sensitivity (CS) between spatial frequencies of 3.0 to 18.0 cpd was significantly different (all P \ 0.05) between Groups 1 and 2. The CS at all spatial frequencies was significantly different (all P \ 0.05) between Group 3 and other two groups. At 3.0-18.0 cpd, CS decreased significantly (all P \ 0.05) in Groups 1-3. Manifest Yiyong Xian and Ling Sun contributed equally and should therefore both be regarded as first authors.

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Efecto de los segmentos anulares intracorneales en la topografía corneal posterior en ojos con queratocono

Berty

Eliwa

Gaafar

et al. 2022

Archivos de la Sociedad Española de Oftalmología

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Effects of Preoperative Topometric Indices on Visual Gain After Intracorneal Ring Segment Implantation For Keratoconus

Abstract: Preoperative ISV value seems to be beneficial in predicting visual gain after ICRS implantation, in addition to SimKavg. Future work on new nomograms for ICRS selection that include ISV, besides refractive, topographic, and cone location data, is warranted.

Cited by 8 publications

References 9 publications

The number of intracorneal ring segments in asymmetric and central cones

The number of intracorneal ring segments in asymmetric and central cones

The Characteristics of Quick Contrast Sensitivity Function in Keratoconus and Its Correlation with Corneal Topography

Efecto de los segmentos anulares intracorneales en la topografía corneal posterior en ojos con queratocono

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