A prism is defined as a portion of a refracting medium bordered by two plane surfaces which are inclined at a finite angle. It deviates light toward its base and causes objects to appear displaced toward its apex. Prisms are used diagnostically to measure ocular alignment and fusional reserves, and therapeutically to treat conditions like convergence insufficiency by strengthening the convergence reflex through base-out prism exercises.
Scleral lens case report series beyond the corneal bordersHossein Mirzaie
This document is an introduction to a book titled "Scleral Lens Case Report Series: Beyond the Corneal Borders". It discusses how scleral lenses that rest on the sclera rather than the cornea can be beneficial for irregular corneas by avoiding contact with the cornea. While scleral lens fitting was previously only done by a few specialists, improved manufacturing has made scleral lenses more widely available from multiple manufacturers. This has expanded the types of conditions that can be treated with scleral lenses. The book contains case reports from practitioners to share knowledge about scleral lens fitting and management.
telescope
1. Telescopes
2. Telescopes represent an effective way of producing magnification without changing the working distance. Disadvantages They have a restricted field of view Often used to focus on objects closer than infinity Can be modified to correct for the Px’s refractive error.
3. There are two basic kinds of Telescope. Keplerian or Astronomical
4. Galilean Telescopes
1. Gonioscopy is a technique used to evaluate the anterior chamber angle by using specialized contact lenses called goniolenses to eliminate total internal reflection and allow visualization of angle structures.
2. There are two main types of goniolenses - direct goniolenses that provide a direct view, and indirect goniolenses that provide a mirror image view using prisms.
3. Important structures visible on gonioscopy include Schwalbe's line, the trabecular meshwork, scleral spur, ciliary body band, and root of iris. Angle width can be graded using systems like Shaffer or Van Herick.
This document provides an overview of the anatomy and structure of the vitreous. It discusses that the vitreous begins forming early in development as the primary vitreous, which appears as the optic cup forms and fills the vitreous space. The vitreous can be divided into the hyaloid layer, cortical vitreous, and medullary vitreous. The hyaloid layer has attachments anteriorly and posteriorly. The cortical vitreous forms the peripheral zone and contains cells. The central vitreous takes up most of the volume and lacks cells. The document also reviews the biochemical composition and transport processes of the vitreous.
ELEVATION BASED CORNEAL TOPOGRAPHY.pptxBipin Koirala
This document discusses corneal topography and elevation-based topography systems. It provides details on corneal anatomy and optics, how elevation-based topographers like the Pentacam work using Scheimpflug imaging and rotating cameras, and how they can measure the anterior and posterior corneal surfaces to generate elevation maps. Interpretation of topography maps is also covered, explaining parameters like curvature, power, astigmatism, and how factors like asphericity and shape asymmetries are evaluated.
This document discusses transformations of graphs including translations, stretches, and reflections. It defines vertical and horizontal translations as shifting the graph of a function up or down by adding a constant c, or shifting it left or right by changing the input by a constant b. Stretches are defined as vertically stretching by a scale factor a or horizontally by 1/a. Reflections are defined as reflecting the graph across the x or y-axis. Examples and exercises are provided to illustrate each type of transformation.
A prism is defined as a portion of a refracting medium bordered by two plane surfaces which are inclined at a finite angle. It deviates light toward its base and causes objects to appear displaced toward its apex. Prisms are used diagnostically to measure ocular alignment and fusional reserves, and therapeutically to treat conditions like convergence insufficiency by strengthening the convergence reflex through base-out prism exercises.
Scleral lens case report series beyond the corneal bordersHossein Mirzaie
This document is an introduction to a book titled "Scleral Lens Case Report Series: Beyond the Corneal Borders". It discusses how scleral lenses that rest on the sclera rather than the cornea can be beneficial for irregular corneas by avoiding contact with the cornea. While scleral lens fitting was previously only done by a few specialists, improved manufacturing has made scleral lenses more widely available from multiple manufacturers. This has expanded the types of conditions that can be treated with scleral lenses. The book contains case reports from practitioners to share knowledge about scleral lens fitting and management.
telescope
1. Telescopes
2. Telescopes represent an effective way of producing magnification without changing the working distance. Disadvantages They have a restricted field of view Often used to focus on objects closer than infinity Can be modified to correct for the Px’s refractive error.
3. There are two basic kinds of Telescope. Keplerian or Astronomical
4. Galilean Telescopes
1. Gonioscopy is a technique used to evaluate the anterior chamber angle by using specialized contact lenses called goniolenses to eliminate total internal reflection and allow visualization of angle structures.
2. There are two main types of goniolenses - direct goniolenses that provide a direct view, and indirect goniolenses that provide a mirror image view using prisms.
3. Important structures visible on gonioscopy include Schwalbe's line, the trabecular meshwork, scleral spur, ciliary body band, and root of iris. Angle width can be graded using systems like Shaffer or Van Herick.
This document provides an overview of the anatomy and structure of the vitreous. It discusses that the vitreous begins forming early in development as the primary vitreous, which appears as the optic cup forms and fills the vitreous space. The vitreous can be divided into the hyaloid layer, cortical vitreous, and medullary vitreous. The hyaloid layer has attachments anteriorly and posteriorly. The cortical vitreous forms the peripheral zone and contains cells. The central vitreous takes up most of the volume and lacks cells. The document also reviews the biochemical composition and transport processes of the vitreous.
ELEVATION BASED CORNEAL TOPOGRAPHY.pptxBipin Koirala
This document discusses corneal topography and elevation-based topography systems. It provides details on corneal anatomy and optics, how elevation-based topographers like the Pentacam work using Scheimpflug imaging and rotating cameras, and how they can measure the anterior and posterior corneal surfaces to generate elevation maps. Interpretation of topography maps is also covered, explaining parameters like curvature, power, astigmatism, and how factors like asphericity and shape asymmetries are evaluated.
This document discusses transformations of graphs including translations, stretches, and reflections. It defines vertical and horizontal translations as shifting the graph of a function up or down by adding a constant c, or shifting it left or right by changing the input by a constant b. Stretches are defined as vertically stretching by a scale factor a or horizontally by 1/a. Reflections are defined as reflecting the graph across the x or y-axis. Examples and exercises are provided to illustrate each type of transformation.
It is essential to assess vergence during an eye exam. There are many aspects of vergence response including near point of convergence, jump vergence, and fusional vergence. Near point of convergence is normally less than 12cm and indicates the point at which one eye turns out. Fusional vergence keeps phorias latent using the fusion reflex, and it is important to know a patient's fusional reserves. Clinical values for distance phoria and positive fusional reserves are used to evaluate if a patient is using an appropriate amount of vergence. Accommodation and vergence are related, and relative accommodation and the zone of clear vision should also be considered during assessment.
Vital dyes and stains Used in Ophthalmic Practice.pptxGauriSShrestha
Vital dyes are used in ophthalmology for diagnostic purposes without pharmacological effects. Common vital dyes include fluorescein sodium, rose bengal, lissamine green, methylene blue, indocyanine green, and trypan blue. Each dye has unique absorption and fluorescence properties that allow them to selectively stain tissues or structures in the eye. The dyes are used to detect defects on the ocular surface, assess tear film and lacrimal drainage, and aid in a variety of surgical procedures. Potential side effects vary between dyes and include irritation, staining of other tissues, and toxic reactions.
This document outlines the 7 steps for sketching the curve of a function: 1) Determine the domain, 2) Find critical points, 3) Determine graph direction and max/min, 4) Use the second derivative to find concavity and points of inflection, 5) Find asymptotes, 6) Find intercepts and important points, 7) Combine evidence to graph the function. Key tests are outlined for max/min, concavity, and points of inflection using the first and second derivatives.
The document discusses various tests used to evaluate macular function, including both subjective and objective tests. Subjective tests include visual acuity tests, Amsler grid testing, color vision tests, and photostress testing. Objective tests mentioned include visual evoked potentials (VEP), electroretinography (ERG), and optical coherence tomography (OCT). The advantages and limitations of different tests are provided.
This document discusses various methods for determining the near addition required for presbyopia correction, including dynamic retinoscopy, determining the tentative addition, and age-expected additions. It provides details on techniques like determining the near point of accommodation, using cross cylinders and near duochromes to refine the prescription, and calculating the near addition needed based on the reading distance and a patient's amplitude of accommodation while leaving some accommodation in reserve.
This document discusses various tests used to evaluate tear film adequacy and watering of the eyes. Tests of tear film adequacy include Schirmer tests, tear film break up time tests using fluorescein and rose bengal stains, and tests of marginal tear strip, pH, lysozyme and osmolarity levels. Tests of watering eyes include the ROPLAS test, fluorescein dye disappearance test, lacrimal syringing test, Jones tests, dacryocystography, and lacrimal scintillography. These tests help evaluate for dry eye, infections, obstructions, or other issues affecting tear production or drainage.
This document discusses various aspects of temporal vision:
1) Temporal vision refers to time-related changes in vision and the analysis of luminance over time, such as detecting flickering lights.
2) Temporal stimuli are often modulated sinusoidally over time, varying in depth of modulation and temporal frequency. Higher modulation causes flickering while lower frequencies appear steady.
3) The critical flicker fusion frequency (CFF) is the highest rate at which a flickering light appears fused rather than flickering and depends on factors like luminance.
4) Temporal modulation transfer functions (TMTF) describe sensitivity to modulation at different frequencies, showing band-pass characteristics with reduced sensitivity at very low and
The accommodative-convergence ratio (AC/A) indicates the relationship between the amount of convergence produced by accommodation and the amount of accommodation itself. A normal AC/A ratio is 1:1, meaning 1 diopter of accommodation produces 1 meter angle of convergence. The gradient method and heterophoria method are two clinical tests used to measure the AC/A ratio. An abnormally high AC/A ratio can be managed optically, pharmacologically, or surgically through techniques such as plus lenses or bifocals to reduce accommodative convergence.
Anatomy and Physiology of Aqueous Humor Sumit Singh Maharjan
2. Anatomy
3. Angle of anterior chamber
4. Angle of the Anterior chamber
5. Gonioscopic grading of Angle
6. Aqueous Outflow system
7. Trabecular meshwork
8. Functions of Aqueous Humor • Maintenance of Intraocular pressure • Metabolic role cornea lens vitreous and retina • Optical function • Clearing function
9. Physicochemical properties • volume: 0.31ml (0.25ml in Ant. Chamber and 0.06 in post chamber) • Refractive index: 1.336 • Density: slightly greater than water, its viscocity is 1.025-1.040 • Osmotic pressure: slightly hyperosmotic to plasma by 3-5mosm/l • PH: 7.2 • Rate of formation: 2-2.5microliter/min
10. Biochemical composition • Water: 99.9% • Proteins: 5-16mg/100ml • Amino acids: aqueous/plasma concentration varies from 0.08-3.14 • Non colloidal constituents: conc. of ascorbate, pyruvate, lactate in higher am
Contact lenses were first used in 1880 and were made of glass, but modern contact lenses are made of soft hydrogel or rigid gas-permeable materials. Contact lenses have several optical advantages over glasses such as a larger field of vision, smaller changes in image size with different viewing angles, and less induced astigmatism and prism. The tear layer between a contact lens and the cornea acts as an optical lens (tear lens) that partially corrects astigmatism and influences the final refractive power. Characteristics of different types of contact lenses like soft, rigid gas-permeable and scleral lenses are described for correcting various refractive errors and irregular corneas.
what is Duochrome Test, Why do we take Red and Green color only,
What is the Principal of Duochrome Test, Why Hyperopic Pt sees green better than red and vice versa
Hypermetropia, also known as farsightedness, occurs when parallel rays of light focus behind the retina instead of on it. There are several types and causes of hypermetropia. Simple hypermetropia is the most common form and is often hereditary. Symptoms include headache, blurry near vision, and asthenopia. Treatment options include prescribing convex lenses, contact lenses, or spectacles with eye patching.
IO-Efficient Point Location and Map Overlay in Low-Density Subdivisionsshripadthite
This document discusses algorithms for point location and map overlay in low-density subdivisions. It introduces the problems of point location, where given a point in a map you find the containing region, and map overlay, where you compute intersections between edges of two maps. It describes challenges with massive geographic data and the need for external memory algorithms. The document presents algorithms for these problems on low-density triangulations and maps based on building compressed quadtrees indexed by a Z-order curve in external memory, allowing efficient point location, map overlay, and updates.
We have asked the geospatial Industry thoguht leaders, their viewpoints on the business and technology directions for 2015. They have given some amazing and extensive views for Geospatial World January 2015 edition.
We treid to summarize the key points that emerged from all of them in to this presentation Geospatial Insights 2015 for your reference.
- See more at: http://geospatialworld.net/Paper/Business/ArticleView.aspx?aid=31290
The document discusses using plugins in QGIS to catalog and access local image files. The Image Boundary plugin is used to create a grid shapefile from a directory of image files, delineating the extent of each image. The Catalog on the Fly plugin allows accessing the image files by their address field, and provides tools to highlight and zoom to images from within QGIS. An expression is also provided to extract the date from Landsat images to populate a date field for use in cataloging.
It is essential to assess vergence during an eye exam. There are many aspects of vergence response including near point of convergence, jump vergence, and fusional vergence. Near point of convergence is normally less than 12cm and indicates the point at which one eye turns out. Fusional vergence keeps phorias latent using the fusion reflex, and it is important to know a patient's fusional reserves. Clinical values for distance phoria and positive fusional reserves are used to evaluate if a patient is using an appropriate amount of vergence. Accommodation and vergence are related, and relative accommodation and the zone of clear vision should also be considered during assessment.
Vital dyes and stains Used in Ophthalmic Practice.pptxGauriSShrestha
Vital dyes are used in ophthalmology for diagnostic purposes without pharmacological effects. Common vital dyes include fluorescein sodium, rose bengal, lissamine green, methylene blue, indocyanine green, and trypan blue. Each dye has unique absorption and fluorescence properties that allow them to selectively stain tissues or structures in the eye. The dyes are used to detect defects on the ocular surface, assess tear film and lacrimal drainage, and aid in a variety of surgical procedures. Potential side effects vary between dyes and include irritation, staining of other tissues, and toxic reactions.
This document outlines the 7 steps for sketching the curve of a function: 1) Determine the domain, 2) Find critical points, 3) Determine graph direction and max/min, 4) Use the second derivative to find concavity and points of inflection, 5) Find asymptotes, 6) Find intercepts and important points, 7) Combine evidence to graph the function. Key tests are outlined for max/min, concavity, and points of inflection using the first and second derivatives.
The document discusses various tests used to evaluate macular function, including both subjective and objective tests. Subjective tests include visual acuity tests, Amsler grid testing, color vision tests, and photostress testing. Objective tests mentioned include visual evoked potentials (VEP), electroretinography (ERG), and optical coherence tomography (OCT). The advantages and limitations of different tests are provided.
This document discusses various methods for determining the near addition required for presbyopia correction, including dynamic retinoscopy, determining the tentative addition, and age-expected additions. It provides details on techniques like determining the near point of accommodation, using cross cylinders and near duochromes to refine the prescription, and calculating the near addition needed based on the reading distance and a patient's amplitude of accommodation while leaving some accommodation in reserve.
This document discusses various tests used to evaluate tear film adequacy and watering of the eyes. Tests of tear film adequacy include Schirmer tests, tear film break up time tests using fluorescein and rose bengal stains, and tests of marginal tear strip, pH, lysozyme and osmolarity levels. Tests of watering eyes include the ROPLAS test, fluorescein dye disappearance test, lacrimal syringing test, Jones tests, dacryocystography, and lacrimal scintillography. These tests help evaluate for dry eye, infections, obstructions, or other issues affecting tear production or drainage.
This document discusses various aspects of temporal vision:
1) Temporal vision refers to time-related changes in vision and the analysis of luminance over time, such as detecting flickering lights.
2) Temporal stimuli are often modulated sinusoidally over time, varying in depth of modulation and temporal frequency. Higher modulation causes flickering while lower frequencies appear steady.
3) The critical flicker fusion frequency (CFF) is the highest rate at which a flickering light appears fused rather than flickering and depends on factors like luminance.
4) Temporal modulation transfer functions (TMTF) describe sensitivity to modulation at different frequencies, showing band-pass characteristics with reduced sensitivity at very low and
The accommodative-convergence ratio (AC/A) indicates the relationship between the amount of convergence produced by accommodation and the amount of accommodation itself. A normal AC/A ratio is 1:1, meaning 1 diopter of accommodation produces 1 meter angle of convergence. The gradient method and heterophoria method are two clinical tests used to measure the AC/A ratio. An abnormally high AC/A ratio can be managed optically, pharmacologically, or surgically through techniques such as plus lenses or bifocals to reduce accommodative convergence.
Anatomy and Physiology of Aqueous Humor Sumit Singh Maharjan
2. Anatomy
3. Angle of anterior chamber
4. Angle of the Anterior chamber
5. Gonioscopic grading of Angle
6. Aqueous Outflow system
7. Trabecular meshwork
8. Functions of Aqueous Humor • Maintenance of Intraocular pressure • Metabolic role cornea lens vitreous and retina • Optical function • Clearing function
9. Physicochemical properties • volume: 0.31ml (0.25ml in Ant. Chamber and 0.06 in post chamber) • Refractive index: 1.336 • Density: slightly greater than water, its viscocity is 1.025-1.040 • Osmotic pressure: slightly hyperosmotic to plasma by 3-5mosm/l • PH: 7.2 • Rate of formation: 2-2.5microliter/min
10. Biochemical composition • Water: 99.9% • Proteins: 5-16mg/100ml • Amino acids: aqueous/plasma concentration varies from 0.08-3.14 • Non colloidal constituents: conc. of ascorbate, pyruvate, lactate in higher am
Contact lenses were first used in 1880 and were made of glass, but modern contact lenses are made of soft hydrogel or rigid gas-permeable materials. Contact lenses have several optical advantages over glasses such as a larger field of vision, smaller changes in image size with different viewing angles, and less induced astigmatism and prism. The tear layer between a contact lens and the cornea acts as an optical lens (tear lens) that partially corrects astigmatism and influences the final refractive power. Characteristics of different types of contact lenses like soft, rigid gas-permeable and scleral lenses are described for correcting various refractive errors and irregular corneas.
what is Duochrome Test, Why do we take Red and Green color only,
What is the Principal of Duochrome Test, Why Hyperopic Pt sees green better than red and vice versa
Hypermetropia, also known as farsightedness, occurs when parallel rays of light focus behind the retina instead of on it. There are several types and causes of hypermetropia. Simple hypermetropia is the most common form and is often hereditary. Symptoms include headache, blurry near vision, and asthenopia. Treatment options include prescribing convex lenses, contact lenses, or spectacles with eye patching.
IO-Efficient Point Location and Map Overlay in Low-Density Subdivisionsshripadthite
This document discusses algorithms for point location and map overlay in low-density subdivisions. It introduces the problems of point location, where given a point in a map you find the containing region, and map overlay, where you compute intersections between edges of two maps. It describes challenges with massive geographic data and the need for external memory algorithms. The document presents algorithms for these problems on low-density triangulations and maps based on building compressed quadtrees indexed by a Z-order curve in external memory, allowing efficient point location, map overlay, and updates.
We have asked the geospatial Industry thoguht leaders, their viewpoints on the business and technology directions for 2015. They have given some amazing and extensive views for Geospatial World January 2015 edition.
We treid to summarize the key points that emerged from all of them in to this presentation Geospatial Insights 2015 for your reference.
- See more at: http://geospatialworld.net/Paper/Business/ArticleView.aspx?aid=31290
The document discusses using plugins in QGIS to catalog and access local image files. The Image Boundary plugin is used to create a grid shapefile from a directory of image files, delineating the extent of each image. The Catalog on the Fly plugin allows accessing the image files by their address field, and provides tools to highlight and zoom to images from within QGIS. An expression is also provided to extract the date from Landsat images to populate a date field for use in cataloging.
How to Create GIS and BIM InteroperabilitySafe Software
Discover how to solve the most common problems with BIM and GIS integration. See how to easily move data between IFC, Autodesk Revit, SketchUp 2015, Esri ArcGIS, AutoCAD, and more. You'll also learn how to use automated techniques to get simplified BIM geometries into GIS, combine attribute or tabular data with existing models, perform space extraction, QC data, and much more.
(1) This chapter discusses trees, which are subgraphs of graphs that connect all vertices with the minimum number of edges.
(2) Three important trees are analyzed: breath first search (BFS) trees, depth first search (DFS) trees, and minimum spanning trees (MST). BFS starts from a root vertex and explores neighboring vertices level-by-level.
(3) The plugin allows generating and visualizing different trees for a graph, and displays properties of the trees like predecessor vertices and exploration levels. This helps learn graph theory concepts in an interactive way.
A line-simplifying and line-rectifying toolGiuliano Curti
The document describes the author's process in developing a Python script to simplify and rectify SHP linestring layers by removing unnecessary points. The author's initial goal was to clean contour line data obtained from a DEM, but they later learned this could be done in QGIS using fTools. Testing showed the author's script performed similarly to fTools at reducing points while also removing some points fTools retained. The author analyzes differences in the algorithms and shares their experimental script and approach in simplifying and rectifying linestring layers.
1. vectGeoref
Un plugin per la georeferenziazione di layer
vettoriali in QGIS
(A plugin for georeferencing of vector layers in QGIS)
Vers.001
10 febbraio 2014
giuliano curti
2. Obiettivi del plugin
(Objectives of the plugin)
●
Il plugin si prefigge di consentire le operazioni adatte
a trasformare un layer vettoriale da un sistema di
riferimento ad un altro (The plugin is intended to enable the
operations suitable to transform a vector layer from a reference
system to another)
●
Caso tipico è quello di dover inserire in una mappa
georeferenziata un disegno di origine CAD sviluppato
in un sistema di riferimento locale (Typical case is that of
having to enter in a geo-referenced map a source drawing CAD
developed in a local reference system)
4. Una Amministrazione comunale dispone di un
sistema cartografico digitale per la gestione del
proprio territorio, ad es. QGIS
(A local council has a digital mapping system for the
management of its territory, eg. QGIS)
5. Il rilievo dell'area interessata viene estrato
dall'archivio
(The relief of the affected area is extracted from the archive)
6. Il team CAD produce una variante all'incrocio
stradale in un proprio sistema di riferimento (The
CAD team produces a variant intersection road in its own
reference system)
7. Si converte il progetto in formato SHP
(It converts the project in SHP format)
8. Ed adesso il problema diventa quello di collimarlo
con la base cartografica di partenza (And now the
question becomes how to fit the cartographic basis starting)
9. Vengono definite le coppie di punti corrispondenti
(Are defined the pairs of corresponding points)
10. Ed ecco il risultato dell'operazione
(And here is the result of the operation)
24. Architettura del plugin
(Plugin Architecture)
●
Il legame di passaggio fra i due sistemi di riferimento è rappresentato
tipicamente da coppie di punti: ad un punto del sistema di origine
corrisponde un punto nel sistema di destinazione, pertanto nel seguito verrà
spesso usato il termine ”collimazione” di punti (The binding of passage between
the two reference systems is typically represented by pairs of points: a point of origin of the
system corresponds to a point in the target system, therefore in the following will be often
used the term "collimation" of points)
●
Esiste una corrispondenza biunivoca fra numero di punti (per l'esattezza
coppie di punti) e tipo di trasformazione (There is a correspondence between the
number of points (to be exact pairs of points) and type of processing)
25. Architettura del plugin
(Plugin Architecture)
●
Collimazione ad 1 punto (leggasi: 1 coppia di punti)
corrisponde ad una traslazione (Collimation to 1 point (read: a
couple of points) corresponds to a translation)
●
Collimazione a 2 punti corrisponde ad una rototraslazione(*) (Collimation in two points corresponds to a rototranslation)
●
Collimazione a 3 o più punti corrisponde ad una rototraslazione con scalatura anisotropa (Collimation at 3 or more
points corresponds to a roto-translation with scaling anisotropic)
(*) Può immaginarsi anche una rototraslazione con
scalatura isotropa qui non implementata (Can you imagine even
a rototranslation with isotropic scaling is not implemented here)
26. Fine della presentazione (The end),
Grazie (thanks and sorry for my bad english).
Giuliano Curti
(giulianc51 at gmail dot com)
