Measurement and Topography Guided Treatment of Irregular Astigmatism

AbstractWe investigated the relation between corneal regular and irregular astigmatism in normal human eyes. In 951 eyes of 951 patients, corneal irregular astigmatism, such as asymmetry and higher-order irregularity components, was calculated using the Fourier harmonic analysis of corneal topography data within the central 3-mm zone of the anterior corneal surface. The eyes were classified by the type of corneal regular astigmatism into four groups; minimum (< 0.75 diopters), with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism. The mean age was significantly different among the four groups (P < 0.001); patients with WTR astigmatism were the youngest, followed by those with minimum, oblique, and ATR astigmatism. Significant inter-group differences were found among the four groups in asymmetry (P = 0.005) and higher-order irregularity components (P < 0.001); the largest was in eyes with oblique astigmatism, followed by ATR, WTR, and minimum astigmatism. The stepwise multiple regression analysis revealed that corneal regular astigmatism pattern significantly influenced the amount of corneal irregular astigmatism after controlling for confounding factors (P < 0.001). Corneal irregular astigmatism, such as asymmetry and higher order irregularity components, was the largest in eyes with oblique astigmatism, followed by those with ATR, WTR, and minimum astigmatism, even after adjustment for age of subjects.

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Possibilities of scleral lenses for visual rehabilitation of patients with corneal scars

Modern technologies in ophtalmology ◽

10.25276/2312-4911-2021-5-157-161 ◽

2021 ◽

pp. 157-161

Author(s):

O.I. Ryabenko ◽

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O.M. Selina ◽

E.M. Tananakina ◽

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...

Keyword(s):

Visual Acuity ◽

Contact Lenses ◽

Efficacy And Safety ◽

Visual Rehabilitation ◽

Optical Correction ◽

Vision Correction ◽

Post Traumatic ◽

Key Words Cornea ◽

Irregular Astigmatism ◽

Spectacle Correction

Purpose. To analyze the efficacy and safety of SCL in patients with corneal cicatricial changes and other concomitant conditions. Material and мethods. The study included 19 patients (20 eyes) with cicatricial deformity of the cornea of various etiology, who were fitted with scleral contact lenses. Results and discussions. The use of SCL is possible in post-traumatic pathology, such as corneoscleral scars with or without aphakia, as well as after keratitis with an outcome in cicatricial deformity, cicatricial changes after a burn. A significant increase in visual acuity compared with spectacle correction has been proven. Depending on the topography of the scar, it is possible to select scleral lenses such as Oblate and Prolate, as well as with different versions of the support zone: both toric and quadratic. Conclusion. Scleral lenses can be successfully used for optical correction in patients with cicatricial changes in the cornea and other concomitant post-traumatic conditions of ineffectiveness of other methods of visual rehabilitation. Key words: cornea, lenses, vision correction, contact lenses, visual rehabilitation, scleral lenses, corneal scars, post-traumatic astigmatism, aphakia, keratitis, toric lenses, quadratic lenses, astigmatism, irregular cornea, regular cornea, regular astigmatism, irregular cornea, irregular astigmatism, prolate, oblate.

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