Higher-Order Aberrations Due to the Posterior Corneal Surface in Patients with Keratoconus

Nakagawa, Tomoya; Maeda, Naoyuki; Kosaki, Ryo; Hori, Yuichi; Inoue, Tomoyuki; Saika, Makoto; Mihashi, Toshifumi; Fujikado, Takashi; Tano, Yasuo

doi:10.1167/iovs.08-2754

Cited by 95 publications

(80 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…17 In addition to anterior corneal aberrations, posterior corneal aberrometric data are useful for keratoconus diagnosis. 69,70 Nakagawa et al 69 found large amounts of primary coma in the anterior and posterior corneal surfaces (primary coma RMS anterior/posterior: 3.57/0.87 mm) in 28 keratoconic eyes, although coma from the posterior surface compensated partly for that from the anterior surface. The Scheimpflug photography-based Pentacam system, (anterior and posterior corneal topography analyzer, corneal aberrometer, pachymeter, and anterior segment biometer) was the first commercially available topographer to provide an estimation of the wavefront aberrations of the posterior corneal surface, although with some limitations and inaccuracies.…”

Section: Corneal Aberrometric Analysis In Keratoconusmentioning

confidence: 99%

Characterization of corneal structure in keratoconus

Piñero¹,

Nieto²,

López-Miguel³

2012

Journal of Cataract and Refractive Surgery

137

113

View full text Add to dashboard Cite

Section: Corneal Aberrometric Analysis In Keratoconusmentioning

confidence: 99%

Characterization of corneal structure in keratoconus

Piñero¹,

Nieto²,

López-Miguel³

2012

Journal of Cataract and Refractive Surgery

137

113

View full text Add to dashboard Cite

“…This is unexpected given the small refractive index difference between aqueous and cornea. Meanwhile, other studies have found much higher aberrations at the anterior surface than at the posterior surface using different instruments, including, the scanning slit Bausch & Lomb (Houston, TX, USA) Orbscan, 10,11 a laboratory Scheimpflug imager, 12,13 the Pentacam, 14 and anterior segment optical coherence tomography (SS-1000; Tomey, Nagoya, Japan). 15 These studies used different analyses including Fourier decomposition of the surfaces, 10 raytracing through surfaces, 12,13,15 and comparing the surface shapes with ideal (aberration-free) shapes.…”

mentioning

confidence: 99%

“…15 These studies used different analyses including Fourier decomposition of the surfaces, 10 raytracing through surfaces, 12,13,15 and comparing the surface shapes with ideal (aberration-free) shapes. 11,14 A potential problem with the latter approaches arises if the object for the posterior cornea is set at infinity rather than that corresponding to refraction by the anterior cornea, as the choice of object position affects aberration estimates.…”

mentioning

confidence: 99%

Anterior Corneal, Posterior Corneal, and Lenticular Contributions to Ocular Aberrations

Atchison

Suheimat

Mathur

et al. 2016

Invest. Ophthalmol. Vis. Sci.

View full text Add to dashboard Cite

PURPOSE. To determine the corneal surfaces and lens contributions to ocular aberrations.METHODS. There were 61 healthy participants with ages ranging from 20 to 55 years and refractions À8.25 diopters (D) to þ3.25 D. Anterior and posterior corneal topographies were obtained with an Oculus Pentacam, and ocular aberrations were obtained with an iTrace aberrometer. Raytracing through models of corneas provided total corneal and surface component aberrations for 5-mm-diameter pupils. Lenticular contributions were given as differences between ocular and corneal aberrations. Theoretical raytracing investigated influence of object distance on aberrations.RESULTS. Apart from defocus, the highest aberration coefficients were horizontal astigmatism, horizontal coma, and spherical aberration. Most correlations between lenticular and ocular parameters were positive and significant, with compensation of total corneal aberrations by lenticular aberrations for 5/12 coefficients. Anterior corneal aberrations were approximately three times higher than posterior corneal aberrations and usually had opposite signs. Corneal topographic centers were displaced from aberrometer pupil centers by 0.32 6 0.19 mm nasally and 0.02 6 0.16 mm inferiorly; disregarding corneal decentration relative to pupil center was significant for oblique astigmatism, horizontal coma, and horizontal trefoil. An object at infinity, rather than at the image in the anterior cornea, gave incorrect aberration estimates of the posterior cornea.CONCLUSIONS. Corneal and lenticular aberration magnitudes are similar, and aberrations of the anterior corneal surface are approximately three times those of the posterior surface. Corneal decentration relative to pupil center has significant effects on oblique astigmatism, horizontal coma, and horizontal trefoil. When estimating component aberrations, it is important to use correct object/image conjugates and heights at surfaces.

show abstract

“…4,11,12 The vertical coma is dominant and the angle of coma is in a similar range for the majority of eyes with keratoconus. Therefore, the purpose of this study was to assess whether six standardized SCLs made using silicone hydrogel and having different vertically asymmetric power distributions could effectively correct irregular astigmatism in patients with keratoconus.…”

Section: Discussionmentioning

confidence: 99%

“…4,11,12 Most of these eyes have vertical coma where the wavefront is fast in the superior portion and slow in the inferior portion due to a superior-inferior asymmetry of the shape of the cornea in eyes with keratoconus. 4 Therefore, like standard clothing sizes (small, medium, large) or current toric SCLs, it might be possible to create semicustomized SCLs for keratoconus with a standardized coma design (consisting of the standardized amount and a particular axis of coma) that could be easily and inexpensively prescribed as standardized sets of lenses.…”

mentioning

confidence: 99%

Visual Performance and Optical Quality of Standardized Asymmetric Soft Contact Lenses in Patients With Keratoconus

Suzaki

Maeda

Fuchihata

et al. 2017

Invest. Ophthalmol. Vis. Sci.

Self Cite

View full text Add to dashboard Cite

Citation: Suzaki A, Maeda N, Fuchihata M, Koh S, Nishida K, Fujikado T. Visual performance and optical quality of standardized asymmetric soft contact lenses in patients with keratoconus. Invest Ophthalmol Vis Sci. 2017;58:289958: -290558: . DOI:10.1167 PURPOSE. To evaluate the visual performance and optical quality of a standardized asymmetric soft contact lens (SCL) used for correction of higher-order aberrations (HOAs) in eyes with keratoconus. METHODS.We included 30 eyes (26 patients) with keratoconus (average K: 45.7 6 2.3 diopters [D]). The patients were subjected to corneal tomography, aberrometry, measurements of manifest refraction and visual acuity (VA), and visual analog scale (VAS) assessments. The study lenses were made using a molding method and consisted of six standardized types, in which an asymmetric power distribution of approximately 2 to 12 D (2-D step) was used to correct HOAs. The lens type suitable for each eye was selected based on the corneal tomography and aberrometry data. The on-eye performance of the lens was evaluated using aberrometry (4-mm pupil), over refraction, VA, and VAS.RESULTS. The standardized asymmetric SCL improved the best spectacle-corrected VA from À0.07 6 0.09 to À0.11 6 0.08 logMAR (P < 0.05) and the mean VAS score from 66.2 6 21.8 to 75.4 6 20.5 (P < 0.05). Vertical coma decreased significantly (À0.50 6 0.36 lm without SCL; À0.36 6 0.34 lm with SCL; P < 0.01). In subgroup analysis, subjects in the high VAS group (score ‡ 75) accounted for 70% of all subjects, and this was the group in which the vertical coma decreased significantly from the level without the lens. CONCLUSIONS.A standardized asymmetric SCL can reduce HOAs and improve vision quality when compared with spectacles in patients with keratoconus who wear rigid gas-permeable lenses.

show abstract

Higher-Order Aberrations Due to the Posterior Corneal Surface in Patients with Keratoconus

Cited by 95 publications

References 39 publications

Characterization of corneal structure in keratoconus

Characterization of corneal structure in keratoconus

Anterior Corneal, Posterior Corneal, and Lenticular Contributions to Ocular Aberrations

Visual Performance and Optical Quality of Standardized Asymmetric Soft Contact Lenses in Patients With Keratoconus

Contact Info

Product

Resources

About