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Related Concept Videos

Glaucoma: Overview01:25

Glaucoma: Overview

Glaucoma is an eye condition characterized by increased intraocular pressure that damages the retina and optic nerve, leading to irreversible blindness if left untreated. The human eye has various components, including the cornea, iris, pupil, lens, and optic nerve. Aqueous humor is secreted by the epithelium of the ciliary body in the posterior chamber and flows through the trabecular meshwork and canal of Schlemm, maintaining normal intraocular pressure. The trabecular meshwork and the canal...
Open Angle Glaucoma: Treatment01:27

Open Angle Glaucoma: Treatment

In open-angle glaucoma, the iridocorneal angle remains open, but the trabecular meshwork becomes stiff, slowing down the outflow of aqueous humor. This causes a buildup of aqueous humor in the anterior chamber, leading to a sudden increase in intraocular pressure. The treatment for open-angle glaucoma focuses on reducing the elevated intraocular pressure by either decreasing the secretion of aqueous humor or increasing its outflow.
Drugs such as carbonic anhydrase inhibitors, α2- and...
Angle Closure Glaucoma: Treatment01:28

Angle Closure Glaucoma: Treatment

Angle-closure glaucoma, or closed-angle glaucoma, is an eye condition where the iris bulges out and blocks the iridocorneal angle, resulting in a buildup of aqueous humor and increased intraocular pressure. Immediate medical attention is necessary due to the sudden onset of symptoms. The treatment for angle-closure glaucoma includes short-term and long-term approaches. Short-term treatment involves using eye drops like pilocarpine to lower intraocular pressure by increasing aqueous humor...
Focusing of Light in the Eye01:16

Focusing of Light in the Eye

Light rays enter the eye through the cornea, a transparent dome-shaped tissue that is the eye's outermost layer. The cornea bends or refracts, light rays traveling to the pupil. The shape of the cornea determines how much of the light is bent and whether the image will be focused correctly on the retina at the back of the eye. Once the light has passed through both refraction layers, it converges into a single focal point onto a small area. This is where photoreceptors start transforming...
Photoreceptors and Visual Pathways01:22

Photoreceptors and Visual Pathways

At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
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Geometry of Hyperbolas

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Related Experiment Video

Updated: Jul 3, 2026

Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients
07:06

Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients

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[Astigmatism].

N Woltsche1, P Werkl2, L Posch-Pertl2

  • 1Univ.-Augenklinik Graz, Medizinische Universität Graz, Auenbruggerplatz 4, 8036, Graz, Österreich. n.woltsche@medunigraz.at.

Der Ophthalmologe : Zeitschrift Der Deutschen Ophthalmologischen Gesellschaft
|February 21, 2019
PubMed
Summary
This summary is machine-generated.

Astigmatism, a common refractive error, involves differentiating internal and external types. Understanding its 3D nature and employing vector analysis aids in planning effective treatments like glasses, toric contacts, or various surgical options.

Keywords:
Ocular residual astigmatismRefraction errorTomographyTopographyToric intraocular lens

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Area of Science:

  • Ophthalmology
  • Optometry
  • Refractive Surgery

Background:

  • Astigmatism is the most prevalent refractive error globally, exceeding hyperopia and myopia.
  • Differentiating internal and external astigmatism is crucial for accurate diagnosis.
  • External astigmatism is classified as 'with the rule', 'against the rule', or 'oblique'.

Purpose of the Study:

  • To elucidate the comprehensive understanding of astigmatism, encompassing its classification and analytical methodologies.
  • To highlight the evolution of astigmatism analysis from 2D to 3D perspectives.
  • To review current treatment modalities for astigmatism.

Main Methods:

  • Distinguishing between internal and external astigmatism components.
  • Utilizing 3D analytical methods like topography and tomography.
  • Applying Alpins' vector analysis for treatment planning.

Main Results:

  • The summation of internal and external astigmatism determines the refractive cylinder.
  • A 3D consideration provides expanded analytical insights beyond traditional 2D views.
  • Vector analysis is instrumental in guiding astigmatism correction strategies.

Conclusions:

  • Accurate astigmatism assessment requires differentiating its internal and external components.
  • Three-dimensional analysis and vector methods enhance treatment planning for astigmatism.
  • A range of conservative and surgical options are available for astigmatism correction.