Phacodynamics refers to the fundamental principles of inflow, outflow, vacuum, and phaco power modulation during cataract surgery. Understanding these principles helps optimize machine settings for different surgical techniques. The foot pedal controls irrigation, aspiration, and ultrasound energy. Position 1 provides irrigation only, position 2 adds aspiration, and position 3 engages ultrasound. Peristaltic and venturi pumps differ in how they create vacuum. Peristaltic pumps require tip occlusion while venturi pumps create vacuum instantly. Factors like compliance, surge, and vent type impact fluidics and safety. Mastering phacodynamics leads to independent surgical skill.
The Scheimpflug principle allows for imaging of the anterior eye segment with maximal depth of focus. Scheimpflug systems like the Pentacam and Orbscan use this principle to provide detailed tomography and topography maps of the cornea and anterior chamber. The Pentacam uses a rotating Scheimpflug camera combined with a static camera to construct a 3D model from 25,000 data points. It analyzes parameters like corneal thickness, curvature, astigmatism, and anterior chamber dimensions. The Orbscan uses slit scanning to create elevation maps of the anterior and posterior corneal surfaces and measure pachymetry. Both devices help evaluate conditions like keratoconus and guide refractive surgery planning.
This document discusses the diagnosis of pre-perimetric glaucoma. It begins by defining pre-perimetric glaucoma as optic nerve abnormalities seen on structural tests with normal visual fields. It then discusses the need for early diagnosis before functional changes occur. Various functional tests are described like standard automated perimetry, short wavelength automated perimetry, frequency doubling technology, and others. Structural tests like confocal scanning laser ophthalmoscopy, optical coherence tomography, and their principles are summarized.
This document provides an overview of modern options for correcting presbyopia. It discusses both static and dynamic correction techniques. Static techniques include glasses, contact lenses, corneal procedures like inlays/onlays, and intraocular lenses using monovision or being multifocal. Dynamic techniques aim to restore accommodation and include accommodating intraocular lenses, lens refilling procedures, and scleral expansion techniques. The document provides details on many of these specific procedures.
This document discusses various techniques and considerations for phacoemulsification cataract surgery. It covers traditional and modern power modes to maximize efficiency while minimizing energy dispersed in the eye. It also discusses fluidic concepts like inflow, outflow and maintaining anterior chamber stability to avoid surge and minimize damage. Different pump types like peristaltic and venturi are compared in terms of vacuum safety and fragment capture ability. Nucleus removal techniques like divide and conquer, stop and chop, and quick chop are outlined. Maintaining a safe central zone and matching instrument size to incision size are also recommended.
This document discusses corneal collagen cross linking (C3R), a treatment for keratoconus. It begins by describing keratoconus and its symptoms. It then discusses the original C3R protocol developed by Seiler and Spoerl, which involves removing the corneal epithelium, soaking the cornea in riboflavin, and exposing it to UV light. Modifications to the protocol aim to reduce complications by using higher irradiance for less time, different riboflavin delivery methods, and leaving the epithelium intact. Studies show C3R increases corneal collagen bonds and rigidity while halting keratoconus progression in most cases. Contraindications and post-op care are also outlined
1) Toric IOLs are used to correct corneal astigmatism during cataract surgery. They have a cylindrical optic to neutralize corneal astigmatism.
2) The material and design of toric IOLs affect their postoperative rotational stability, with acrylic IOLs showing the highest stability. Larger diameter and loop haptic designs also increase stability.
3) Proper patient selection, preoperative measurements, surgical technique, and IOL alignment are important for achieving optimal visual outcomes with toric IOL implantation. Accurate axis alignment is critical to achieve the intended astigmatic correction.
Phacodynamics refers to the fundamental principles of inflow, outflow, vacuum, and phaco power modulation during cataract surgery. Understanding these principles helps optimize machine settings for different surgical techniques. The foot pedal controls irrigation, aspiration, and ultrasound energy. Position 1 provides irrigation only, position 2 adds aspiration, and position 3 engages ultrasound. Peristaltic and venturi pumps differ in how they create vacuum. Peristaltic pumps require tip occlusion while venturi pumps create vacuum instantly. Factors like compliance, surge, and vent type impact fluidics and safety. Mastering phacodynamics leads to independent surgical skill.
The Scheimpflug principle allows for imaging of the anterior eye segment with maximal depth of focus. Scheimpflug systems like the Pentacam and Orbscan use this principle to provide detailed tomography and topography maps of the cornea and anterior chamber. The Pentacam uses a rotating Scheimpflug camera combined with a static camera to construct a 3D model from 25,000 data points. It analyzes parameters like corneal thickness, curvature, astigmatism, and anterior chamber dimensions. The Orbscan uses slit scanning to create elevation maps of the anterior and posterior corneal surfaces and measure pachymetry. Both devices help evaluate conditions like keratoconus and guide refractive surgery planning.
This document discusses the diagnosis of pre-perimetric glaucoma. It begins by defining pre-perimetric glaucoma as optic nerve abnormalities seen on structural tests with normal visual fields. It then discusses the need for early diagnosis before functional changes occur. Various functional tests are described like standard automated perimetry, short wavelength automated perimetry, frequency doubling technology, and others. Structural tests like confocal scanning laser ophthalmoscopy, optical coherence tomography, and their principles are summarized.
This document provides an overview of modern options for correcting presbyopia. It discusses both static and dynamic correction techniques. Static techniques include glasses, contact lenses, corneal procedures like inlays/onlays, and intraocular lenses using monovision or being multifocal. Dynamic techniques aim to restore accommodation and include accommodating intraocular lenses, lens refilling procedures, and scleral expansion techniques. The document provides details on many of these specific procedures.
This document discusses various techniques and considerations for phacoemulsification cataract surgery. It covers traditional and modern power modes to maximize efficiency while minimizing energy dispersed in the eye. It also discusses fluidic concepts like inflow, outflow and maintaining anterior chamber stability to avoid surge and minimize damage. Different pump types like peristaltic and venturi are compared in terms of vacuum safety and fragment capture ability. Nucleus removal techniques like divide and conquer, stop and chop, and quick chop are outlined. Maintaining a safe central zone and matching instrument size to incision size are also recommended.
This document discusses corneal collagen cross linking (C3R), a treatment for keratoconus. It begins by describing keratoconus and its symptoms. It then discusses the original C3R protocol developed by Seiler and Spoerl, which involves removing the corneal epithelium, soaking the cornea in riboflavin, and exposing it to UV light. Modifications to the protocol aim to reduce complications by using higher irradiance for less time, different riboflavin delivery methods, and leaving the epithelium intact. Studies show C3R increases corneal collagen bonds and rigidity while halting keratoconus progression in most cases. Contraindications and post-op care are also outlined
1) Toric IOLs are used to correct corneal astigmatism during cataract surgery. They have a cylindrical optic to neutralize corneal astigmatism.
2) The material and design of toric IOLs affect their postoperative rotational stability, with acrylic IOLs showing the highest stability. Larger diameter and loop haptic designs also increase stability.
3) Proper patient selection, preoperative measurements, surgical technique, and IOL alignment are important for achieving optimal visual outcomes with toric IOL implantation. Accurate axis alignment is critical to achieve the intended astigmatic correction.
This document compares and contrasts AS-OCT (anterior segment optical coherence tomography) and ultrasound biomicroscopy (UBM) imaging techniques for evaluating the anterior eye segment.
It discusses that AS-OCT provides non-contact, high resolution cross-sectional imaging of the anterior segment structures without touching the eye. UBM uses high frequency ultrasound to generate detailed 2D images of the anterior segment, allowing visualization of structures like the iris and angle.
While both techniques allow qualitative and quantitative assessment of the anterior chamber angle and structures, AS-OCT has advantages of being non-contact, faster imaging, and less operator dependency compared to UBM. However, UBM can image deeper into the posterior iris and has greater penetration than
The document discusses various formulas used for calculating intraocular lens (IOL) power, including SRK, SRK2, Holladay, Haigis, and Holladay 2. It explains the factors these formulas account for such as axial length, corneal power, anterior chamber depth, and how they have evolved over generations to improve accuracy. Special considerations for calculating IOL power in cases involving prior refractive surgery, silicone oil filling, posterior staphyloma, and using optical biometry devices are also summarized.
This document provides an overview of the history and evolution of cataract surgery techniques from ancient times to modern techniques. It discusses early techniques like couching and intracapsular cataract extraction. It then covers the development of extracapsular cataract extraction and intraocular lens implantation. More recent advances discussed include small incision cataract surgery, phacoemulsification, microincision cataract surgery, femtosecond laser-assisted cataract surgery, and research into zero-energy cataract surgery. The document traces the progression of cataract surgery from early crude techniques to the highly precise procedures used today and under development for the future.
This document summarizes corneal collagen shrinkage and collagen crosslinking techniques. It discusses how collagen shrinkage was initially used to treat keratoconus through heating methods but had limitations due to necrosis. Collagen crosslinking was developed to strengthen corneal collagen through riboflavin and UV light exposure based on the Dresden Protocol. Variations including accelerated and customized protocols aim to treat thinner corneas and focal disease. While generally safe and effective for keratoconus, complications can include haze, infection, and continued progression requiring proper technique. New applications investigate refractive corrections and other corneal conditions.
This document provides an overview of a course on using femtosecond lasers for cataract and astigmatism surgery. It discusses the LenSx laser, which was the first femtosecond laser cleared by the FDA for use in cataract surgery. The LenSx laser allows for precise cuts to the anterior capsule, lens fragmentation, and corneal incisions through integrated OCT imaging and a curved patient interface. Studies show benefits like improved capsulotomy accuracy and consistency compared to manual techniques.
This document provides information on giant retinal tears, including:
1. Giant retinal tears are defined as circumferential retinal tears greater than 90 degrees. They require urgent management to prevent further retinal detachment from proliferative vitreoretinopathy.
2. Causes include idiopathic, trauma, high myopia, and certain genetic conditions. Surgical procedures like LASIK and phakic IOLs can also cause giant retinal tears.
3. Vitrectomy is the standard treatment, involving removal of the vitreous gel, retinopexy, and an internal tamponade of long-acting gas or silicone oil to reattach the retina. Perfluorocarbon liquids help stabilize the retina
The document discusses various aspects of patient evaluation and treatment options for refractive surgery. It describes evaluating a patient's psychosocial factors, medical and ocular history, and examination findings to determine suitability for different refractive surgery techniques. A variety of surgical options are outlined including corneal procedures like LASIK, PRK, and lens-based procedures. Topics like wavefront analysis and assessing higher-order aberrations are also summarized.
This document discusses various techniques for corneal collagen crosslinking (CXL), a procedure to strengthen the cornea using riboflavin and UV light. It describes the pathogenesis of keratoconus and history of CXL. The standard Dresden protocol involves epithelial removal followed by riboflavin drops and 30 minutes of UV light exposure. Variations discussed include accelerated CXL, hypo-osmolar CXL for thin corneas, transepithelial CXL, and contact lens-assisted CXL. The document provides details on riboflavin solutions, irradiation parameters, and indications and contraindications for CXL.
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.
The Ocular Hypertension Treatment Study (OHTS) was a landmark randomized controlled trial that showed treating patients with ocular hypertension reduced the risk of developing primary open-angle glaucoma by more than 50% compared to observation alone. Increased risk factors for developing glaucoma included older age, larger cup-to-disc ratios, higher baseline intraocular pressure, and thinner central corneal thickness. The Early Manifest Glaucoma Trial found that treating newly diagnosed glaucoma patients lowered their intraocular pressure by 25% on average and reduced the risk of visual field progression by about 20% compared to no treatment. The Collaborative Initial Glaucoma Treatment Study found that both medical and surgical treatment were effective for initially lowering intra
Keratoprosthesis is a surgical procedure that replaces a severely damaged or diseased cornea with an artificial cornea to restore vision. The first attempts at keratoprosthesis in humans date back to the mid-19th century, but most implants failed. Modern keratoprosthesis designs like the Boston KPro and AlphaCor KPro sandwich a donor corneal graft between plastic plates. Complications can include melting/extrusion of the implant, infection, glaucoma, retinal detachment, and formation of membranes behind the implant. Close post-operative monitoring is required to manage complications and maintain vision with keratoprosthesis implants.
The basis of manual small incision cataract surgery is the tunnel construction for entry to the anterior chamber.
The parameters important for the structural integrity of the tunnel are the self-sealing property of the tunnel, the location of the wound on the sclera with respect to the limbus, and the shape of the wound.
Cataract surgery has gone beyond just being a means to get the lens out of the eye.
Postoperative astigmatism plays an important role in the evaluation of final outcome of surgery. Astigmatic consideration, hence, forms an integral part of incisional considerations prior to surgery.
This document discusses the history and evolution of intraocular lens (IOL) power calculation methods. It begins by describing problems with pre-IOL era cataract treatment using thick "Coke bottle bottom" spectacles. The first successful IOL implantation was performed by Sir Harold Ridley in 1949 using a PMMA lens. Early IOL power calculations often had errors over 1 diopter. The document then covers the development of theoretical formulas, regression formulas like SRK I, and modified formulas like Holladay I and Haigis that incorporate additional ocular measurements like axial length, corneal power, and anterior chamber depth to improve accuracy. Modern devices like the IOL Master and Lenstar are also able to precisely measure these parameters to
This document discusses various biometry instruments and equipment used to calculate intraocular lens (IOL) power for cataract surgery. It describes how keratometry, A-scan ultrasound biometry, and non-contact devices like the IOLMaster measure important ocular dimensions needed for IOL power calculations, including corneal power, axial length, and anterior chamber depth. It also discusses IOL power calculation formulas from first to fourth generation and factors that influence formula choice, such as eye length, anterior chamber depth, and IOL placement in the eye. Accurate biometry is emphasized as key to achieving the desired postoperative refractive outcome.
This document discusses tips for calculating intraocular lens (IOL) power in difficult situations. It begins by outlining situations that can make IOL power calculation challenging, such as previous refractive surgery, high astigmatism, previous keratoplasty, pediatric cases, eyes with silicone oil or posterior staphyloma.
It then provides details on methods to calculate IOL power in each situation, including using previous refractive data, topography readings, and specialized formulas. Optical biometry is generally preferred over ultrasound biometry in difficult cases. The document emphasizes using third and fourth generation formulas and online calculators.
Special considerations are discussed for cases like piggyback IOLs, aphakia,
Corneal topography provides detailed maps of the cornea's shape and curvature. It uses Placido disc or computerized videokeratography techniques to measure thousands of data points across the cornea. Topography is useful for diagnosing conditions like keratoconus that cause corneal shape changes. It can also guide surgical planning for refractive procedures and evaluate outcomes of surgeries like LASIK. Topography patterns are analyzed using color-coded maps to identify areas of steep and flat curvature and irregularities. The data helps with contact lens fitting and suture removal after corneal surgery.
This document discusses posterior capsule tears that can occur during cataract surgery. It covers the predisposing factors, mechanisms, identification, and management strategies for posterior capsule tears with or without vitreous loss. Key points include identifying tears early, stabilizing the anterior chamber with viscoelastic, deciding whether to continue phacoemulsification or convert to extracapsular extraction based on the situation, performing anterior vitrectomy when needed with caution to minimize further vitreous disturbance, and properly placing an IOL. The goal is to remove all lens material and prevent further complications while minimizing additional surgery.
Vitreous substitutes are substances used during vitreoretinal surgery to re-establish intraocular volume, assist with separating membranes from the retina, and manipulate and flatten detached retina. They are also used postoperatively as long-term tamponading agents to maintain the retina in apposition. Common vitreous substitutes used include balanced salt solution, air, viscoelastic fluids, silicone liquid, and perfluorocarbon liquids. Gases such as air, SF6, and C3F8 are employed during retinal detachment surgery to provide internal tamponade and are chosen based on their duration, expansion properties, and buoyancy effects. Complications can include increased intraocular pressure, lens opac
LASIK or Lasik (laser-assisted in situ keratomileusis), commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and an actual cure for astigmatism, since it is in the cornea. LASIK surgery is performed by an ophthalmologist who uses a laser or microkeratome to reshape the eye's cornea in order to improve visual acuity. For most people, LASIK provides a long-lasting alternative to eyeglasses or contact lenses.
The planning and analysis of corneal reshaping techniques such as LASIK have been standardized by the American National Standards Institute, an approach based on the Alpins method of astigmatism analysis. The FDA website on LASIK states,
"Before undergoing a refractive procedure, you should carefully weigh the risks and benefits based on your own personal value system, and try to avoid being influenced by friends that have had the procedure or doctors encouraging you to do so."
The procedure involves creating a thin flap on the eye, folding it to enable remodeling of the tissue beneath with a laser and repositioning the flap.
This document discusses microincision vitrectomy surgery (MIVS) using smaller gauge instruments for vitreoretinal surgery. It describes the historical development of vitrectomy from larger 20 gauge systems to newer 23, 25, and 27 gauge systems. Key aspects of MIVS instrumentation and techniques are summarized, including trocar/cannula systems, self-sealing wound construction, challenges with smaller gauges, and advances in vitrectomy machines and illumination systems to improve efficiency and safety with MIVS.
This document compares and contrasts AS-OCT (anterior segment optical coherence tomography) and ultrasound biomicroscopy (UBM) imaging techniques for evaluating the anterior eye segment.
It discusses that AS-OCT provides non-contact, high resolution cross-sectional imaging of the anterior segment structures without touching the eye. UBM uses high frequency ultrasound to generate detailed 2D images of the anterior segment, allowing visualization of structures like the iris and angle.
While both techniques allow qualitative and quantitative assessment of the anterior chamber angle and structures, AS-OCT has advantages of being non-contact, faster imaging, and less operator dependency compared to UBM. However, UBM can image deeper into the posterior iris and has greater penetration than
The document discusses various formulas used for calculating intraocular lens (IOL) power, including SRK, SRK2, Holladay, Haigis, and Holladay 2. It explains the factors these formulas account for such as axial length, corneal power, anterior chamber depth, and how they have evolved over generations to improve accuracy. Special considerations for calculating IOL power in cases involving prior refractive surgery, silicone oil filling, posterior staphyloma, and using optical biometry devices are also summarized.
This document provides an overview of the history and evolution of cataract surgery techniques from ancient times to modern techniques. It discusses early techniques like couching and intracapsular cataract extraction. It then covers the development of extracapsular cataract extraction and intraocular lens implantation. More recent advances discussed include small incision cataract surgery, phacoemulsification, microincision cataract surgery, femtosecond laser-assisted cataract surgery, and research into zero-energy cataract surgery. The document traces the progression of cataract surgery from early crude techniques to the highly precise procedures used today and under development for the future.
This document summarizes corneal collagen shrinkage and collagen crosslinking techniques. It discusses how collagen shrinkage was initially used to treat keratoconus through heating methods but had limitations due to necrosis. Collagen crosslinking was developed to strengthen corneal collagen through riboflavin and UV light exposure based on the Dresden Protocol. Variations including accelerated and customized protocols aim to treat thinner corneas and focal disease. While generally safe and effective for keratoconus, complications can include haze, infection, and continued progression requiring proper technique. New applications investigate refractive corrections and other corneal conditions.
This document provides an overview of a course on using femtosecond lasers for cataract and astigmatism surgery. It discusses the LenSx laser, which was the first femtosecond laser cleared by the FDA for use in cataract surgery. The LenSx laser allows for precise cuts to the anterior capsule, lens fragmentation, and corneal incisions through integrated OCT imaging and a curved patient interface. Studies show benefits like improved capsulotomy accuracy and consistency compared to manual techniques.
This document provides information on giant retinal tears, including:
1. Giant retinal tears are defined as circumferential retinal tears greater than 90 degrees. They require urgent management to prevent further retinal detachment from proliferative vitreoretinopathy.
2. Causes include idiopathic, trauma, high myopia, and certain genetic conditions. Surgical procedures like LASIK and phakic IOLs can also cause giant retinal tears.
3. Vitrectomy is the standard treatment, involving removal of the vitreous gel, retinopexy, and an internal tamponade of long-acting gas or silicone oil to reattach the retina. Perfluorocarbon liquids help stabilize the retina
The document discusses various aspects of patient evaluation and treatment options for refractive surgery. It describes evaluating a patient's psychosocial factors, medical and ocular history, and examination findings to determine suitability for different refractive surgery techniques. A variety of surgical options are outlined including corneal procedures like LASIK, PRK, and lens-based procedures. Topics like wavefront analysis and assessing higher-order aberrations are also summarized.
This document discusses various techniques for corneal collagen crosslinking (CXL), a procedure to strengthen the cornea using riboflavin and UV light. It describes the pathogenesis of keratoconus and history of CXL. The standard Dresden protocol involves epithelial removal followed by riboflavin drops and 30 minutes of UV light exposure. Variations discussed include accelerated CXL, hypo-osmolar CXL for thin corneas, transepithelial CXL, and contact lens-assisted CXL. The document provides details on riboflavin solutions, irradiation parameters, and indications and contraindications for CXL.
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.
The Ocular Hypertension Treatment Study (OHTS) was a landmark randomized controlled trial that showed treating patients with ocular hypertension reduced the risk of developing primary open-angle glaucoma by more than 50% compared to observation alone. Increased risk factors for developing glaucoma included older age, larger cup-to-disc ratios, higher baseline intraocular pressure, and thinner central corneal thickness. The Early Manifest Glaucoma Trial found that treating newly diagnosed glaucoma patients lowered their intraocular pressure by 25% on average and reduced the risk of visual field progression by about 20% compared to no treatment. The Collaborative Initial Glaucoma Treatment Study found that both medical and surgical treatment were effective for initially lowering intra
Keratoprosthesis is a surgical procedure that replaces a severely damaged or diseased cornea with an artificial cornea to restore vision. The first attempts at keratoprosthesis in humans date back to the mid-19th century, but most implants failed. Modern keratoprosthesis designs like the Boston KPro and AlphaCor KPro sandwich a donor corneal graft between plastic plates. Complications can include melting/extrusion of the implant, infection, glaucoma, retinal detachment, and formation of membranes behind the implant. Close post-operative monitoring is required to manage complications and maintain vision with keratoprosthesis implants.
The basis of manual small incision cataract surgery is the tunnel construction for entry to the anterior chamber.
The parameters important for the structural integrity of the tunnel are the self-sealing property of the tunnel, the location of the wound on the sclera with respect to the limbus, and the shape of the wound.
Cataract surgery has gone beyond just being a means to get the lens out of the eye.
Postoperative astigmatism plays an important role in the evaluation of final outcome of surgery. Astigmatic consideration, hence, forms an integral part of incisional considerations prior to surgery.
This document discusses the history and evolution of intraocular lens (IOL) power calculation methods. It begins by describing problems with pre-IOL era cataract treatment using thick "Coke bottle bottom" spectacles. The first successful IOL implantation was performed by Sir Harold Ridley in 1949 using a PMMA lens. Early IOL power calculations often had errors over 1 diopter. The document then covers the development of theoretical formulas, regression formulas like SRK I, and modified formulas like Holladay I and Haigis that incorporate additional ocular measurements like axial length, corneal power, and anterior chamber depth to improve accuracy. Modern devices like the IOL Master and Lenstar are also able to precisely measure these parameters to
This document discusses various biometry instruments and equipment used to calculate intraocular lens (IOL) power for cataract surgery. It describes how keratometry, A-scan ultrasound biometry, and non-contact devices like the IOLMaster measure important ocular dimensions needed for IOL power calculations, including corneal power, axial length, and anterior chamber depth. It also discusses IOL power calculation formulas from first to fourth generation and factors that influence formula choice, such as eye length, anterior chamber depth, and IOL placement in the eye. Accurate biometry is emphasized as key to achieving the desired postoperative refractive outcome.
This document discusses tips for calculating intraocular lens (IOL) power in difficult situations. It begins by outlining situations that can make IOL power calculation challenging, such as previous refractive surgery, high astigmatism, previous keratoplasty, pediatric cases, eyes with silicone oil or posterior staphyloma.
It then provides details on methods to calculate IOL power in each situation, including using previous refractive data, topography readings, and specialized formulas. Optical biometry is generally preferred over ultrasound biometry in difficult cases. The document emphasizes using third and fourth generation formulas and online calculators.
Special considerations are discussed for cases like piggyback IOLs, aphakia,
Corneal topography provides detailed maps of the cornea's shape and curvature. It uses Placido disc or computerized videokeratography techniques to measure thousands of data points across the cornea. Topography is useful for diagnosing conditions like keratoconus that cause corneal shape changes. It can also guide surgical planning for refractive procedures and evaluate outcomes of surgeries like LASIK. Topography patterns are analyzed using color-coded maps to identify areas of steep and flat curvature and irregularities. The data helps with contact lens fitting and suture removal after corneal surgery.
This document discusses posterior capsule tears that can occur during cataract surgery. It covers the predisposing factors, mechanisms, identification, and management strategies for posterior capsule tears with or without vitreous loss. Key points include identifying tears early, stabilizing the anterior chamber with viscoelastic, deciding whether to continue phacoemulsification or convert to extracapsular extraction based on the situation, performing anterior vitrectomy when needed with caution to minimize further vitreous disturbance, and properly placing an IOL. The goal is to remove all lens material and prevent further complications while minimizing additional surgery.
Vitreous substitutes are substances used during vitreoretinal surgery to re-establish intraocular volume, assist with separating membranes from the retina, and manipulate and flatten detached retina. They are also used postoperatively as long-term tamponading agents to maintain the retina in apposition. Common vitreous substitutes used include balanced salt solution, air, viscoelastic fluids, silicone liquid, and perfluorocarbon liquids. Gases such as air, SF6, and C3F8 are employed during retinal detachment surgery to provide internal tamponade and are chosen based on their duration, expansion properties, and buoyancy effects. Complications can include increased intraocular pressure, lens opac
LASIK or Lasik (laser-assisted in situ keratomileusis), commonly referred to as laser eye surgery or laser vision correction, is a type of refractive surgery for the correction of myopia, hyperopia, and an actual cure for astigmatism, since it is in the cornea. LASIK surgery is performed by an ophthalmologist who uses a laser or microkeratome to reshape the eye's cornea in order to improve visual acuity. For most people, LASIK provides a long-lasting alternative to eyeglasses or contact lenses.
The planning and analysis of corneal reshaping techniques such as LASIK have been standardized by the American National Standards Institute, an approach based on the Alpins method of astigmatism analysis. The FDA website on LASIK states,
"Before undergoing a refractive procedure, you should carefully weigh the risks and benefits based on your own personal value system, and try to avoid being influenced by friends that have had the procedure or doctors encouraging you to do so."
The procedure involves creating a thin flap on the eye, folding it to enable remodeling of the tissue beneath with a laser and repositioning the flap.
This document discusses microincision vitrectomy surgery (MIVS) using smaller gauge instruments for vitreoretinal surgery. It describes the historical development of vitrectomy from larger 20 gauge systems to newer 23, 25, and 27 gauge systems. Key aspects of MIVS instrumentation and techniques are summarized, including trocar/cannula systems, self-sealing wound construction, challenges with smaller gauges, and advances in vitrectomy machines and illumination systems to improve efficiency and safety with MIVS.
Refractive surgeries aim to correct refractive errors like myopia, hyperopia and astigmatism by altering the cornea or lens. Techniques include excimer laser ablation under a corneal flap (LASIK), surface ablation procedures like PRK, and newer procedures like ReLEx. Excimer and femtosecond lasers are commonly used to precisely reshape the cornea. Selection criteria consider factors like corneal thickness and pupillary size to minimize risks. Post-operative care and monitoring is important for stabilization and recovery.
Pachymetry is the measurement of corneal thickness. The central corneal thickness in normal eyes ranges from 0.49 to 0.56 mm. Thicker corneas can indicate endothelial decompensation. Several techniques are used to measure corneal thickness including ultrasonic pachymetry, specular microscopy, optical coherence tomography, and confocal microscopy. Measurement of corneal thickness is important for diagnosing and managing conditions like glaucoma, refractive surgery, and contact lens wear.
This document summarizes techniques for cataract surgery, including:
1. Cataract surgery has evolved into a refractive procedure to reduce spectacle dependence. Various techniques can be used to correct astigmatism including limbal relaxing incisions and toric IOLs.
2. Accurate biometry measurements of axial length are critical for determining the correct IOL power. Both ultrasound A-scan and optical coherence tomography can be used, with advantages and disadvantages to each.
3. Surgical techniques like capsulorrhexis, hydrodissection, phacoemulsification, and divide-and-conquer are described to efficiently remove the cataract while minimizing complications. Proper wound construction
This document discusses various refractive surgery procedures used to correct refractive errors of the eye, including incisional keratotomy techniques, lamellar procedures, laser ablation procedures, corneal implants, and lens-based procedures. It provides details on common procedures like radial keratotomy, LASIK, PRK, and LASEK. It covers patient evaluation, surgical techniques, potential complications, and advantages of different approaches. Wavefront-guided customized excimer laser surgery is also introduced to correct higher-order aberrations in addition to spherical and cylindrical errors.
This document discusses various corneal ectasias such as keratoconus. It describes the structure of the cornea and the pathophysiology of keratoconus. Symptoms include decreasing vision, irregular astigmatism. Diagnosis involves corneal tomography and biomechanical testing. Management includes contact lenses, corneal collagen cross-linking, and intrastromal corneal ring segments. The Dresden protocol is described for corneal collagen cross-linking using riboflavin and UV light.
This document discusses keratorefractive surgeries. It begins by describing the anatomy of the cornea, including the epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. It then provides a brief history of keratorefractive surgeries and classifications including location, addition, subtraction, relaxation, and compression techniques. Common keratorefractive surgeries discussed include PRK, LASEK, LASIK, epikeratophakia, keratophakia, and excimer laser procedures. Complications, indications, and the role of techniques like corneal topography and wavefront analysis are also summarized.
MIGS procedures aim to lower IOP through minimally invasive surgery with fewer complications than traditional glaucoma surgeries. Procedures include trabecular micro-bypass stents and excimer laser trabeculotomy to increase outflow through the trabecular meshwork, as well as canaloplasty and the Hydrus microstent to dilate Schlemm's canal. Other options are suprachoroidal shunts and subconjunctival implants to divert aqueous humor through alternate outflow pathways. While showing modest IOP reduction, MIGS procedures offer rapid recovery and minimal risk compared to traditional surgeries.
management of corneal scar, penetrating keratoplastyMonaMohammed40
This document provides information on penetrating keratoplasty (corneal transplant surgery). It discusses the history and development of the procedure. The main indications for penetrating keratoplasty are to improve vision, restore the corneal surface, eliminate corneal disease, and relieve pain. The document outlines factors that influence the prognosis, as well as contraindications. It then describes the preoperative evaluation, donor tissue evaluation, surgical instruments used, and techniques for harvesting the donor cornea and transplanting it into the recipient's eye. Suturing techniques like interrupted, continuous, and combined sutures are also summarized.
Lamellar Keratoplasty in ophthalmologypratik mohod
Lamellar keratoplasty involves replacing only the diseased portion of the cornea, leaving the recipient's posterior stroma, Descemet's membrane, and endothelium intact. It is less invasive than penetrating keratoplasty. Deep lamellar endothelial keratoplasty (DLEK) and Descemet's stripping automated endothelial keratoplasty (DSAEK) specifically replace only the recipient's diseased endothelium with donor tissue. DLEK is performed through a large limbal incision while DSAEK strips off the recipient's Descemet's membrane through a small incision. Both techniques aim to provide faster visual recovery and avoid complications compared to penetrating keratoplasty.
This document discusses contact lens fitting following various refractive surgeries. It begins with an introduction to refractive surgeries like radial keratotomy, PRK, LASIK, LASEK, SMILE, and others. It then discusses considerations and techniques for fitting contact lenses after different surgeries, focusing on fitting rigid gas permeable lenses, mini-scleral lenses, and hybrid lenses following procedures like radial keratotomy that can result in irregular astigmatism. The document provides guidance on lens parameters and fitting criteria to achieve a stable, comfortable fit while maintaining corneal health after refractive surgery.
Perché come chirurgo scegliere tecniche SMILE SMAL LENTICULE CORSO_23Feb24 Po...Nicola Canali
un vantaggio razionale nell'utilizzo di correzione refrattiva con SMALL LENTICULE SMILE con FEMTOLASER. Dr.Canali.
a rational advantage in the use of refractive correction with SMALL LENTICULE SMILE with FEMTOLASER
This document discusses accurate biometry and its role in determining the correct intraocular lens power for cataract surgery. It covers techniques for measuring axial length and keratometry, different formulas used in biometric calculations, tips for obtaining accurate measurements, and common sources of error. The goal is to provide surgeons with information to optimize biometry and achieve the best possible postoperative vision outcomes for patients.
This document summarizes the anatomy and physiology of the lens and cataracts. It discusses the location, shape, and structure of the lens. It then describes different types of cataracts such as senile, traumatic, and metabolic cataracts. The document outlines cataract grading systems and explains methods for examining and diagnosing cataracts. It provides details on different intraocular lens options and surgical techniques for treating cataracts, including extracapsular cataract extraction and phacoemulsification. Potential complications of cataract surgery are also mentioned.
1. Dr. Rohit Agrawal presented on the history and techniques of phacoemulsification.
2. Key developments included Charles Kelman's early work in the 1960s and the introduction of foldable IOLs and topical anesthesia in the 1980s.
3. Phacoemulsification uses ultrasound energy and a fluidics system to emulsify and remove the crystalline lens through a small incision. Common techniques discussed were divide and conquer, stop and chop, and vertical and horizontal chopping approaches.
Доклад на Пятой научно-практической конференции с международным участием «Основные тенденции в современной офтальмологии», организованной клиникой профессора Эскиной Э.Н. «Сфера», совместно с кафедрой офтальмологии ФГБОУ ДПО ИПК ФМБА России —→ http://www.sfe.ru/information/ophthalmology-news/conference2015.html
This document discusses corneal surgery, including corneal refractive surgery and corneal transplant surgery. It describes the different types of corneal refractive surgery, which include flap surgery techniques like LASIK as well as surface procedures like PRK. Corneal transplant surgery, also called keratoplasty, is described as replacing damaged corneal tissue with donor tissue. The different types of keratoplasty like penetrating keratoplasty and lamellar keratoplasty are mentioned. The document provides details on donor corneal preparation and storage, surgical techniques, potential complications, and post-operative care for corneal transplant surgery.
This document discusses corneal surgery, including corneal refractive surgery and corneal transplant surgery. It describes the different types of corneal refractive surgery, which include flap surgery techniques like LASIK and surface procedures like PRK. Corneal transplant surgery, also called keratoplasty, is described as replacing damaged corneal tissue with healthy donor tissue. The common techniques used are penetrating keratoplasty and lamellar keratoplasty. The document outlines the donor corneal preparation and storage methods, as well as the surgical techniques and potential complications of corneal transplant surgery.
Similar to Current overview of Microkeratomes (20)
These lecture slides, by Dr Sidra Arshad, offer a simplified look into the mechanisms involved in the regulation of respiration:
Learning objectives:
1. Describe the organisation of respiratory center
2. Describe the nervous control of inspiration and respiratory rhythm
3. Describe the functions of the dorsal and respiratory groups of neurons
4. Describe the influences of the Pneumotaxic and Apneustic centers
5. Explain the role of Hering-Breur inflation reflex in regulation of inspiration
6. Explain the role of central chemoreceptors in regulation of respiration
7. Explain the role of peripheral chemoreceptors in regulation of respiration
8. Explain the regulation of respiration during exercise
9. Integrate the respiratory regulatory mechanisms
10. Describe the Cheyne-Stokes breathing
Study Resources:
1. Chapter 42, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 36, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 13, Human Physiology by Lauralee Sherwood, 9th edition
STUDIES IN SUPPORT OF SPECIAL POPULATIONS: GERIATRICS E7shruti jagirdar
Unit 4: MRA 103T Regulatory affairs
This guideline is directed principally toward new Molecular Entities that are
likely to have significant use in the elderly, either because the disease intended
to be treated is characteristically a disease of aging ( e.g., Alzheimer's disease) or
because the population to be treated is known to include substantial numbers of
geriatric patients (e.g., hypertension).
The skin is the largest organ and its health plays a vital role among the other sense organs. The skin concerns like acne breakout, psoriasis, or anything similar along the lines, finding a qualified and experienced dermatologist becomes paramount.
How to Control Your Asthma Tips by gokuldas hospital.Gokuldas Hospital
Respiratory issues like asthma are the most sensitive issue that is affecting millions worldwide. It hampers the daily activities leaving the body tired and breathless.
The key to a good grip on asthma is proper knowledge and management strategies. Understanding the patient-specific symptoms and carving out an effective treatment likewise is the best way to keep asthma under control.
Summer is a time for fun in the sun, but the heat and humidity can also wreak havoc on your skin. From itchy rashes to unwanted pigmentation, several skin conditions become more prevalent during these warmer months.
“Psychiatry and the Humanities”: An Innovative Course at the University of Mo...Université de Montréal
“Psychiatry and the Humanities”: An Innovative Course at the University of Montreal Expanding the medical model to embrace the humanities. Link: https://www.psychiatrictimes.com/view/-psychiatry-and-the-humanities-an-innovative-course-at-the-university-of-montreal
- Video recording of this lecture in English language: https://youtu.be/Pt1nA32sdHQ
- Video recording of this lecture in Arabic language: https://youtu.be/uFdc9F0rlP0
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
4. TYPICAL COMPONENTS OF A MODERN
MICROKERATOME SYSTEM
• Console
• Motor
• Microkeratome head
• Applanator lenses
• Vacuum fixation
• Flap stop ring , which limits the microkeratome head through the fixation
ring
• Foot switch
6. MOTOR AND MICROKERATOME
HEAD
• Motor of keratome initiates
1. Forward movement of head
2. Oscillation of blade for the cut
7. MODALITIES OF
MICROKERATOME PASS
• Rotative/Pivoting flap creation:
• +: less space needed,
• +: hinge placement variable
• - : flap is thick – thin – thick
due to the upward movement
of the suction ring during the cut
Hansatome, Carriazo
8. • Linear flap creation:
• +: intraop visibility during flap creation,
• +: planar flap profile
• - : fixed hinge position
• Amadeus, SBK
MODALITIES OF
MICROKERATOME PASS
10. SUCTION RING
• Suction ring will induce rise in IOP
• First step choosing right size of suction ring
• Suction ring diameter determines
• How much of the cornea will protrude into the
microkeratome
• primary determinant of flap diameter.
• Steep Cornea more tissue will protrude
• Flat Cornea less tissue will protrude
12. VACUUM SETTING
• Achieving and maintaining adequate vacuum during microkeratome
pass is critical to producing accurate flap.
• IOP at least 65mmHg for most microkeratomes
• Suction system and IOP should always be checked prior to every
procedure
• Lower pressures can produce thinner cuts and irregular flaps
• Higher pressures can lead to chemosis, s/c hemorrhages, optic nerve
injury
13. PLACING THE SUCTION RING
• The LASIK pneumatic suction ring is
placed on the eye.
• With a suction pressure greater than
65 mm Hg, the instrument fixates the
globe at the limbus and provides a
dovetail track for the microkeratome.
14. THE NEED FOR TRANSIENT HIGH IOP
• IOP >65 mm Hg
• Barraquer tonometer, a conical lens
with a flat undersurface marked with
a circle, and convex upper surface that
acts as a magnifier.
• Dry cornea
• Gives uniform microkeratome section
15. MICROKERATOME – PRACTICAL TIPS
• Counsel well before taking the patient
• Briefly explain the procedure :-
1.That it will take 5-7minutes per eye
2.You will feel little pressure on eye
3.For few seconds you won’t see the lights
4.Not to squeeze the eyes
5.Not to move the eyes
6.You will hear some noises of Keratome and the laser machine
16. • Blade assembly and inspection
• Check suction
• Always do a trial pass before actual
procedure
• Listen to sound of blade oscillation
MICROKERATOME – PRACTICAL TIPS
17. • Always do marking on the cornea before keratome pass
Advantages of marking :
1.Proper alignment of the flap post ablation
2.In case of free flap marking will help you to place the flap
in it’s natural position
3.Also helps in identifying the epithelium and stromal side
of free flap
MICROKERATOME – PRACTICAL TIPS
18. ADVANTAGES OF MECHANICAL MICROKERATOMES
• Proven history
• Lower cost
• More efficient surgical flow <30 secs
• Ability to create flaps in anterior stromal opacity/scar
• Less inflammation
19. Laser in situ keratomileusis was performed using the Moria
microkeratome with the
• One Use-Plus SBK,
• M2 90
• M2 110 head.
The SBK head demonstrated the most accurate flap thickness,
followed by the M2 90 head and the 110 head.
20. 1- No difference in visual acuity
2- Dry eye associated with MK and DLK with femto
21. Comparison between:
• Amadeus
• Carriazo
• Moria M2
• SBK
• Nidek
• Hansatome
CONCLUSIONS
1. Variability between all 6 models
2. Device labelling did NOT represent flap thickness achieved
3. Thinner corneas had thinner flaps and similar for thicker corneas
4. 1st cut (1st eye) had a thicker flap in B/L procedures