Aberrations and Topography in Normal, Keratoconus-Suspect, and Keratoconic Eyes

Gordon‐Shaag, Ariela; Millodot, Michel; Ifrah, Reut; Shneor, Einat

doi:10.1097/opx.0b013e318249d727

Cited by 78 publications

(67 citation statements)

References 34 publications

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“…Gordon-Shaag et al [39], reported that corneal higher order aberrations were found to be significantly higher for keratoconic than normal eyes, but for suspect keratoconus the results were mixed. Alio et al [24], has established corneal aberrometry as a potential diagnostic tool for diagnosing keratoconus especially coma-like aberrations.…”

Section: Discussionmentioning

confidence: 98%

Anterior Segment Characteristics of Keratoconus Eyes Using Scheimpflug-Placido Topography

Mostafa¹

2016

J Clin Res Ophthalmol

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Purpose: To assess anterior segment parameters of keratoconus (KC) eyes at different stages of the disease using Scheimpflug-placido topography (Sirius, CSO, Italy) in a sample of the southern Egyptian population.Methods: retrospective study of 400eyes of different grades of keratoconus along with 50 normal eyes as a control group were assessed for the following parameters: corneal thickness at apex (CCT), thinnest corneal thickness (TCT), anterior chamber depth (ACD), corneal volume (CV), corneal keratometry, corneal asphericity (Q), corneal elevation (both anterior and posterior) with aspherotoric surface as a reference, total root mean square (RMS), RMS Coma, RMS spherical aberration (SA), RMS Astigmatism, , Baiocchi Calossi Versaci front index (BCV f ) and BCV back index (BCV b ). They underwent Sirius Schemipflug placid topographer evaluation.Results: eyes were subdivided into: normal group (50 eyes), suspect KC (82eyes), grade 1 KC (80eyes), grade 2 KC (142eyes), and grade 3 KC (96eyes). The thinnest corneal thickness corneal thickness at apex and posterior corneal elevation were significantly different in all comparison groups. ACD values showed inconsistent differences between groups. Corneal volume was proved to be significant in comparing normal vs suspect KC group as well as in normal vs mild KC and normal vs moderate KC. Total RMS, RMS coma and BCV f and BCV b were significant for most groups Conclusion: Corneal thickness and high order aberrations proved to be able to diagnose different grades of keratoconus while corneal volume did not prove to have a significant role.

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Section: Discussionmentioning

confidence: 98%

Anterior Segment Characteristics of Keratoconus Eyes Using Scheimpflug-Placido Topography

Mostafa¹

2016

J Clin Res Ophthalmol

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“…We hypothesize that, given the atypically high rate of lower order aberrations, children from this population may have atypically high levels of HOAs if astigmatic corneas are associated with other surface irregularities, as is seen in keratoconus. 6 We were specifically interested in the relation between astigmatism and the two HOAs that typically contribute the most power in studies of populations: unsigned spherical aberration (z12u) and unsigned coma (root-mean-square z07u and z08u).…”

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confidence: 99%

Higher-order aberrations and best-corrected visual acuity in Native American children with a high prevalence of astigmatism

Miller

Harvey

Schwiegerling

2015

Journal of American Association for Pediatric Ophthalmology and

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Purpose To determine whether higher-order aberrations (HOAs) in children from a highly astigmatic population differ from population norms and whether HOAs are associated with astigmatism and reduced best-corrected visual acuity. Methods Subjects were 218 Tohono O’odham Native American children 5–9 years of age. Noncycloplegic HOA measurements were obtained with a handheld Shack-Hartmann sensor (SHS). Signed (z06s to z14s) and unsigned (z06u to z14u) wavefront aberration Zernike coefficients Z(3,−3) to Z(4,4) were rescaled for a 4 mm diameter pupil and compared to adult population norms. Cycloplegic refraction and best-corrected logMAR letter visual acuity (BCVA) were also measured. Regression analyses assessed the contribution of astigmatism (J0) and HOAs to BCVA. Results The mean root-mean-square (RMS) HOA of 0.191 ± 0.072 μm was significantly greater than population norms (0.100 ± 0.044 μm. All unsigned HOA coefficients (z06u to z14u) and all signed coefficients except z09s, z10s, and z11s were significantly larger than population norms. Decreased BCVA was associated with astigmatism (J0) and spherical aberration (z12u) but not RMS coma, with the effect of J0 about 4 times as great as z12u. Conclusions Tohono O’odham children show elevated HOAs compared to population norms. Astigmatism and unsigned spherical aberration are associated with decreased acuity, but the effects of spherical aberration are minimal and not clinically significant.

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“…The total root mean square (RMS) of the higher order aberrations 17 of nine eyes of seven subjects was compared with and without the RGP scleral contact lens correction Finally, we report the general comfort and satisfaction levels of the subjects using these novel lenses.…”

Section: Discussionmentioning

confidence: 99%

“…The corneal distortions included advanced KC, postpenetrating keratoplasty or KC with other surgical complications. Inclusion criteria for manifest KC were presence of paracentral steepening of the cornea or irregular bowtie astigmatism on topography (video keratoscope), and at least one of the following signs: Stromal thinning, Fleischer's ring or Vogt's striae observed by slit-lamp examination (adapted from Gordon-Shaag et al); 17 and a cone apex equal to or larger than 50 DS, and inferior superior dioptric difference equal to or above 3.5 DS (adapted from Millodot et al). 18 The study protocol was approved by the Hadassah Academic College Ethics Committee and subjects signed a statement of informed consent prior to their participation in the study.…”

Section: Subjectsmentioning

confidence: 99%

A Prospective Clinical Evaluation of a New Scleral Contact Lens for Patients with Distorted Corneas

Fine¹,

Gordon‐Shaag²,

Leibowitz³

et al. 2013

International Journal of Keratoconus and Ectatic Corneal Diseases

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Objectives: A prospective clinical evaluation of the physiological fit and visual performance of a novel commercially available rigid gas permeable (RGP) scleral contact lens in subjects suffering from distorted corneas is described. Materials and methods:The physiological fit and visual performance of 23.5 mm and 21 mm RGP scleral contact lenses were assessed in 14 subjects (22 eyes) and nine subjects (12 eyes), respectively. All but one participant with a distorted cornea as a result of an infection, suffered from varying grades of keratoconus. In a subset of seven subjects (8 eyes), the higher order aberrations were measured with and without the scleral lenses. Results:The 23 mm RGP scleral lens improved visual performance in 82% of the participants and eight subjects were satisfied with the lenses. The 21 mm lens improved visual performance in 83% of the participants, and four subjects were satisfied with the lenses. Subjects that were satisfied with the lenses tended to lack other forms of visual correction. In the seven subjects that were included in the substudy, the total lower order, higher order, coma, and tetrafoil root mean square were significantly reduced (p df=7 < 0.05) with the scleral contact lenses, whereas the total trefoil was not. Conclusion:RGP scleral lenses can be comfortably worn for approximately 7 hours, improve visual acuity, and reduce higher order wavefront aberrations. The lenses can be fit easily by the practitioner, though a trial lens set is necessary. The lenses are recommended in cases where other forms of visual correction can no longer be tolerated and as a long-term or temporary alternative to corneal transplant.

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Aberrations and Topography in Normal, Keratoconus-Suspect, and Keratoconic Eyes

Cited by 78 publications

References 34 publications

Anterior Segment Characteristics of Keratoconus Eyes Using Scheimpflug-Placido Topography

Anterior Segment Characteristics of Keratoconus Eyes Using Scheimpflug-Placido Topography

Higher-order aberrations and best-corrected visual acuity in Native American children with a high prevalence of astigmatism

A Prospective Clinical Evaluation of a New Scleral Contact Lens for Patients with Distorted Corneas

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