Irregular Astigmatism: Diagnosis and Treatment


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Irregular Astigmatism: Diagnosis and Treatment provides everything refractive surgeons, ophthalmologists, and optometrists need to know about this important topic.

Astigmatism Diagnosis & Treatment | St. Petersburg Eye Doctor

Ocular Components of Regular and Irregular Astigmatism. Corneal Biomechanics. Clinical Evaluation of Regular and Irregular Astigmatism. Indications for Penetrating Keratoplasty for Irregular Astigmatism. Lamellar Keratoplasty. Conductive Keratoplasty Treatment for Astigmatism. Wang received his doctorate degree in laser spectroscopy and his post-doctorate fellowship from the University of Maryland in College Park, Maryland, and the Massachusetts Institute of Technology in Boston, Massachusetts, respectively. After completing both a residency in ophthalmology and a fellowship in ocular genetics at the Wills Eye Hospital in Philadelphia, Pennsylvania, he completed a clinical fellowship in cornea and external disease and refractive surgery at the Bascom Palmer Eye Institute, University of Miami School of Medicine in Miami, Florida.

In , he became the founding director of the Vanderbilt Laser Sight Center and a full-time faculty member of the Department of Ophthalmology at the Vanderbilt University School of Medicine. He remained at Vanderbilt for 5 years before he went into private practice in Wang''s research career encompasses three distinctively different fields. From to , he published as the first author of a dozen original papers in the leading physics journal, Physical Review A, describing the development of a novel experimental atomic physics technique that he developed with Professor John Weiner, a Doppler velocity-selected associative ionization process between sodium atoms.

In , Dr.

Irregular Astigmatism Diagnosis and Treatment

Wang turned his inquisitive mind to the study of molecular biology at Harvard and MIT, and published as the first author of a major paper in the world-renowned journal, Nature, regarding a novel molecular biology technique that he invented with Professor George Church, a whole-genome approach to in vivo DNA-protein interaction and gene expression regulation. After research careers in experimental atomic physics and molecular biology, Dr. Wang then began yet another research career in , this time in ophthalmology, ocular genetics, novel anterior segment reconstructive surgeries, and corneal topography.

Working with Professor Larry Donoso, he cloned the first ocular melanoma-associated antigen.

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Wang made an original contribution to the field of corneal wound healing by publishing with Professor Scheffer Tseng the first paper in the literature regarding laboratory success in the reduction of corneal scarring and apoptosis with amniotic membrane transplantation. Wang holds a US patent for his invention of the amniotic membrane contact lens, and he successfully made the first prototype. Wang conducted the first large-scale clinical study and was the principal clinical investigator of the first 3-D stereo corneal topographer, AstraMax. He was the first surgeon from the US to study a new, high frequency excimer laser and treatment-planning platform designed to treat post-LASIK complex eyes.


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Wang performed the first femtosecond laser-assisted artificial cornea implantation. He offers the only fellowship in cornea and external disease and refractive surgery in the state of Tennessee. Digitally processed slitlamp photographs of the anterior lenticonus show marked anterior protrusion of the anterior surface of the lens in patients 1 A and 2 B.

A year-old man was diagnosed with Alport syndrome. He had received a kidney transplant from his father to treat renal failure. He sought treatment for ocular complications at our clinic. Slitlamp examination revealed bilateral anterior lenticonus Figure 1 B. Dot-and-fleck retinopathy was detected in both eyes.

For both patients, videokeratography and wavefront aberrometry were performed with a wavefront analyzer KRPW; Topcon Corporation, Tokyo, Japan 3 to determine simultaneously the corneal irregular astigmatism and the irregular astigmatism in refraction Figure 2 and Figure 3. Maps from a patient with keratoconus Figure 4 and maps of an emmetropic eye Figure 5 are shown as examples of a corneal irregular astigmatism and a healthy control, respectively.

A mire image A , color-coded maps of the anterior corneal surface axial power B and corneal higher-order aberrations C , a Hartmann-Shack data image D , and color-coded maps of total ocular wavefront E and ocular higher-order F aberrations in a patient with lenticonus patient 1. The map of higher-order aberrations due to the anterior corneal surface C indicates minimum higher-order aberrations, and the map of ocular higher-order aberrations F indicates spherical-like aberrations.

These findings indicate that the irregular astigmatism in lenticonus arises from the lens. A mire image A , color-coded maps of the anterior corneal surface axial power B and corneal higher-order aberrations C , a Hartmann-Shack data image D , and color-coded maps of total ocular wavefront E and ocular higher-order F aberrations in a patient with lenticonus patient 2.

The maps of corneal C and ocular F higher-order aberrations have the same pattern changes as seen in patient 1. A mire image A , color-coded maps of the anterior corneal surface axial power B and corneal higher-order aberrations C , a Hartmann-Shack data image D , and color-coded maps of total ocular wavefront E and ocular higher-order F aberrations in a patient with keratoconus.

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The maps of corneal C and ocular F higher-order aberrations show similar patterns. These findings indicate that the irregular astigmatism in keratoconus arises from the cornea. A mire image A , color-coded maps of the anterior corneal surface axial power B and corneal higher-order aberrations C , a Hartmann-Shack data image D , and color-coded maps of total ocular wavefront E and ocular higher-order F aberrations in a patient with emmetropia. The maps of corneal C and ocular F higher-order aberrations show no signs of irregular astigmatism. The maps of the eyes with lenticonus showed a relatively uniform pattern, indicating that the corneal higher-order aberrations were within the normal range Figure 2 C and Figure 3 C.

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Pathologic Causes of Irregular Astigmatism

The map of the keratoconic eye showed a faster wavefront superiorly and a slower wavefront inferiorly, indicating corneal irregular astigmatism with a dominance of coma-like aberration Figure 4 C. For all patients except the patient with emmetropia, the maps for total ocular aberrations showed cooler colors in the center, indicating that the refractions of these eyes were myopic Figure 2 E, Figure 3 E, and Figure 4 E. The map of ocular higher-order aberrations for the keratoconic eye Figure 4 F had a pattern similar to the one seen on the corneal higher-order aberrations map Figure 4 C , suggesting that the irregular astigmatism in refraction originated from the abnormal corneal shape.

In the lenticonic eyes, however, the maps of the higher-order ocular aberrations showed a dominance of spherical-like aberrations Figure 2 F and Figure 3 F. Because the corneal irregular astigmatisms were within the normal range in these eyes, we deduce that most of the irregular astigmatism in refraction originated from a lenticular component. The root mean square values of the higher-order aberrations for 4-mm- and 6-mm-diameter pupils are shown in Table 1.

Astigmatism

As shown in the color-coded maps, ocular spherical-like aberrations were dominant in the lenticonic eyes, and corneal and ocular coma-like aberrations were dominant in the keratoconic eye. Wavefront sensing enables us to evaluate irregular astigmatism qualitatively, from the color-coded maps of the higher-order wavefront aberrations, or quantitatively, as a set of Zernike coefficients.

Although corneal topography is usually designated by powers, higher-order wavefront aberrations due to the cornea can be quantified by calculating a set of Zernike coefficients. It is clinically important that we easily recognize the relationship between the characteristics of the higher-order aberrations and the location of the shape abnormality by using color-coded maps of ocular higher-order aberrations.

Irregular astigmatism induced by lenticonus is a relatively symmetrical, spherical-like aberration because the protrusion of the anterior lens surface and under sclerosis are the center. In contrast, irregular astigmatism in typical keratoconus is an asymmetrical, coma-like aberration due to the displacement of the cone. To determine the source of irregular astigmatism, it is important to separate the higher-order aberrations of the cornea from those of the lens.


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  3. Evaluation of Lenticular Irregular Astigmatism Using Wavefront Analysis in Patients With Lenticonus;
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For this purpose, we believe that it is very important to view simultaneously the map of corneal higher-order aberrations produced by corneal topographic analysis and the map of ocular higher-order aberrations produced by wavefront sensing. In our study, a combination of anterior corneal topography and wavefront aberrometry was used. Therefore, higher-order aberrations due to the lens were estimated indirectly.

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Artal et al 6 more accurately showed the relative contribution of the corneal surface and the internal optics of the eye to the ocular aberrations by immersing the eye in isotonic sodium chloride solution during wavefront sensing. Many questions about lenticular irregular astigmatism, such as the aging effect of the lens, residual irregular astigmatism with contact lens wear, and the effects of intraocular lens design, are still unanswered.

Studies of the simultaneous measurements of corneal higher-order aberrations and higher-order aberrations of the eye will make it possible to answer these questions. Arch Ophthalmol.

Irregular Astigmatism: Diagnosis and Treatment Irregular Astigmatism: Diagnosis and Treatment
Irregular Astigmatism: Diagnosis and Treatment Irregular Astigmatism: Diagnosis and Treatment
Irregular Astigmatism: Diagnosis and Treatment Irregular Astigmatism: Diagnosis and Treatment
Irregular Astigmatism: Diagnosis and Treatment Irregular Astigmatism: Diagnosis and Treatment
Irregular Astigmatism: Diagnosis and Treatment Irregular Astigmatism: Diagnosis and Treatment
Irregular Astigmatism: Diagnosis and Treatment Irregular Astigmatism: Diagnosis and Treatment

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