This document provides information about optical coherence tomography (OCT), laser therapy for diabetic retinopathy, and vitrectomy. It defines OCT as a non-invasive imaging tool using light waves to produce cross-sectional images of the retina. Laser therapy for diabetic retinopathy aims to stimulate the RPE pump and inhibit VEGF release by applying focal or grid laser burns. Vitrectomy surgically removes the vitreous gel through a pars plana approach using small gauge instruments in order to treat various posterior segment conditions by releasing traction and inserting tamponades.
This presentation is mainly focused on the clinical diagnosis and interpretation of oct macula.This is presented on 4th year optometry as topic presentation.
SOLIX Essential is a technology built upon a proven foundation of high-speed Spectral Domain OCT. The SOLIX Essential offers state-of-the-art imaging from the cornea to the choroid with exclusive technology that will change your approach to disease diagnosis and management.
OCT is a great technology,Many ophthalmologist find very difficult to understand it ,SO I have tired to simplify it as much as possible .Hope everyone can understand now onwards the basic about OCT .
Every feedback s most welcomed sothat i can improve further in coming days
Please email your feedback to me in the following address
yourgyanu@gmail.com
The word “laser” is an acronym for light amplification by stimulated emission of radiation. Most sources of visible light radiate energy at different wavelengths (ie, different colors) and at random time intervals (noncoherent). The unique properties of laser energy are monochromaticity (single wavelength), spatial coherence, and high density of electrons. These allow focusing of laser beams to extremely small spots with very high-energy densities.
A laser consists of a transparent crystal rod (solid-state laser), or a gas- or liquid-filled cavity (gas or fluid laser) constructed with a fully reflective mirror at one end and a partially reflective mirror at the other. Surrounding the rod or cavity is an optical or electrical source of energy that will raise the energy level of the atoms within the rod or cavity to a high and unstable level, a process known as population inversion. When the excited atoms spontaneously decay back to a lower-energy level, their excess energy is released in the form of light. This light can be emitted in any direction. In a laser cavity, however, light emitted along the long axis of the cavity can bounce back and forth between the mirrors, setting up a standing wave that stimulates the remaining excited atoms to release their energy into the standing wave, producing an intense beam of light that exits the cavity through the partially reflective mirror. All of the light produced has the same wavelength (monochromatic) and phase (coherent), with little tendency to spread out (low divergence). The laser light energy can be emitted continuously or in pulses, which may have pulse durations of nanoseconds or less.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
More Related Content
Similar to OCT , Laser therapy for DR , Vitrectomy
This presentation is mainly focused on the clinical diagnosis and interpretation of oct macula.This is presented on 4th year optometry as topic presentation.
SOLIX Essential is a technology built upon a proven foundation of high-speed Spectral Domain OCT. The SOLIX Essential offers state-of-the-art imaging from the cornea to the choroid with exclusive technology that will change your approach to disease diagnosis and management.
OCT is a great technology,Many ophthalmologist find very difficult to understand it ,SO I have tired to simplify it as much as possible .Hope everyone can understand now onwards the basic about OCT .
Every feedback s most welcomed sothat i can improve further in coming days
Please email your feedback to me in the following address
yourgyanu@gmail.com
The word “laser” is an acronym for light amplification by stimulated emission of radiation. Most sources of visible light radiate energy at different wavelengths (ie, different colors) and at random time intervals (noncoherent). The unique properties of laser energy are monochromaticity (single wavelength), spatial coherence, and high density of electrons. These allow focusing of laser beams to extremely small spots with very high-energy densities.
A laser consists of a transparent crystal rod (solid-state laser), or a gas- or liquid-filled cavity (gas or fluid laser) constructed with a fully reflective mirror at one end and a partially reflective mirror at the other. Surrounding the rod or cavity is an optical or electrical source of energy that will raise the energy level of the atoms within the rod or cavity to a high and unstable level, a process known as population inversion. When the excited atoms spontaneously decay back to a lower-energy level, their excess energy is released in the form of light. This light can be emitted in any direction. In a laser cavity, however, light emitted along the long axis of the cavity can bounce back and forth between the mirrors, setting up a standing wave that stimulates the remaining excited atoms to release their energy into the standing wave, producing an intense beam of light that exits the cavity through the partially reflective mirror. All of the light produced has the same wavelength (monochromatic) and phase (coherent), with little tendency to spread out (low divergence). The laser light energy can be emitted continuously or in pulses, which may have pulse durations of nanoseconds or less.
Similar to OCT , Laser therapy for DR , Vitrectomy (20)
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
2. OPTICAL COHERENCE
TOMOGRAPHY(OCT)
INTRODUCTION
OCT is a non-contact, noninvasive imaging
diagnostic tool that can perform crossectional
images of biological tissues within less than 10µ
axial resolution using light waves.
It is specially suited for retinal disorders as retina
is easily accessible to external light.
3. BASIC PRINCIPLE
Combination of low-coherence
interferometry with a special
Broadband width light in near
Infrared range(810nm).
A broadband width near-IR light
beam is projected. The beam is
split to the tissue of interest called
as probe beam and to a
reference mirror at a known
variable position.
The light is reflected back from
the boundaries between the micro structures and
is also scattered differently from tissues with
different optical properties .
The echo time delay of the light reflected from
various layers of the retina is compared with echo
time delay of light reflected from the reference
mirror.
4. A positive interference is produced when light
reflected from the retina and reference mirror
arrives simultaneously or within short coherence
length of each other.
This interference is measured by a photodetector
which finally produces a range of time delays for
comparison.
The interferometer integrates several data points
over 2mm of depth to construct a tomogram of
retinal structures.
It is a real-time tomogram using false colour
scale. Different colours represent light
backscattering from different depths of the
retina.
The low-coherence light source determines the
axial resolution which is 10µ for OCT1 & OCT2 ,
and 7-8µ for OCT3. The transverse resolution
depends on the probe beam diameter and is 20µ.
5. THE OCT MACHINE
The OCT system comprises of the following:-
Fundus viewing unit.
Interferometric unit.
Computer display.
Control panel.
Colour inkjet printer.
Generations of commercially available OCT
machine:-
OCT 1- 1st generation OCT machine.
OCT 2- 2nd generation OCT machine.
Both OCT 1 & OCT 2.
OCT 3- 3rd generation OCT unit.
7. PROCEDURE OF OCT
Activation of the machine and entering of patient data
is the first step.
Patient position- the patient’s are dilated and patient
is asked to look into the internal fixation target light in
the ocular lens.
Protocols for scan acquisition is selected as per the
case requirement. The scanning beam is placed on the
area of interest and scans are obtained. The Zeiss
Stratus OCT machine provides 19 scans acquisition
protocols designed for examination of retina and ONH.
Production & display image- On z axis, 1024 points
are captured over a 2mm depth to create a tissue
density profile, with resolution of 10µ. On x-y axis,
tissue density profile is repeated upto 512 times every
5-60µ to generate a cross-sectional image. Several
data points over 2mm of depth are integrated by the
interferometer to construct a tomogram of retinal
structures. Images thus produced has an axial
resolution of 10µ and a transverse resolution of 20µ.
The tomogram is displayed in either gray scale or
false colour on a high resolution computer screen.
8. NORMAL OCT SCAN OF RETINA
The OCT scan of retina allows cross-sectional study of
the macular, peripapillary region including RNFL, &
ONH region.
COLOUR CODING IN OCT SCAN
Red-yellow represent areas of maximal optical
reflection and backscattering.
Blue-black represent areas of minimal signals.
INTERPRETATION OF RETINAL SCAN
Vitreous anterior to the retina is non-reflective and is
seen as a dark space.
Vitreo-retinal interface is well defined due to the
contrast between the non-reflective and the back
scattering retina.
Different intermediate layers of neurosensory retina
betweeen the dark layer of photoreceptor and red
layer of RNFL are seen an alternating layers of
moderate and low reflectivity.
9. THE MACULAR SCAN
Line Scan-It gives an option of acquiring multiple
line scan without returning to main window.
Radial line-It consists of 6-24 equally spaced line
scan that pass through a central common axis.
Macular Thickness-This is same as radial line
except the aiming circle as a fixed diameter of
6mm.
10. OPTIC DISC SCAN
Characteristic description of an optic disc scan is
shown below-
Optic disc boundaries and diameters:The point at
which choriocapillaries terminates at lamina
cribrosa determines the disc boundaries.
Optic cup is determined by the points at which
the nerve fibre layer terminates.
11. CLINICAL APPLICATION OF OCT SCAN
MACULAR DISORDERS:
OCT pictures of some of the important macular lesions is
as below-
1.Macuar hole-OCT allows confirmation of diagnosis of
macular hole and differentiates it from the clinically
stimulating condition such as lamellar hole, course of
disease & response to surgical intervention.
2.Macular oedema-In OCT scan, the macular oedema is
characterised by the intraretinal areas of decreased
reflectivity and retinal thickening.
3.ARMD-Morphological changes in the nonexudative
ARMD. As well as subretinal fluid, intraretinal thickening
& choroidal neovascularization in exudative ARMD.
4.Central serous chorioretinopathy-In OCT scan, the
central serous chorioretinopathy is characterized by an
area of decreased reflectivity between two highly
reflective layers- the neurosensory retina & RPE.
5.Epiretinal membrane is diagnosed on OCT by the
presence of a highly reflective diaphanous membrane
over surface of retina.
12. OCT IN GLAUCOMA
-Glaucoma diagnosis. Optic disc scan is
very useful in diagnosing & monitering
glaucomatous change.
-Useful in evaluating the RNFL for early
glaucoma detection.
-Evaluation of cystoid macular oedema
after combined cataract & glaucoma
surgery.
13. LIMITATIONS OF OCT
Being purely dependent on optical principles, it
requires a minimal pupillary diameter of 4mm to
obtain a high quality image.
OCT has limited applications in patients with poor
media clarity due to corneal oedema, dence
cataracts, vitreous haemorrhages and asteriod
hyalosis.
High astigmatism, decentred IOL can
compromise quality of OCT scan.
Limited transverse sampling.
14. OCT FOR ANTERIOR SEGMENT IMAGING &
BIOMETRY
Anterior segment imaging- The anterior segment
can be evaluated & measured pre &
postoperatively after image acquisition, using the
analysis mode of system’s software.
Corneal imaging & pachymetry –The OCT provies
high-resolution corneal images and
documentation for the anterior segment
specialist to support the evaluation of optical
health.
New LASIK information- In addition to providing
a full-thickness pachymetry map prior to laser
surgery,OCT is the non-contact device to
image,measure and document both corneal flap
thickness and residual stromal thickness
immediately following LASIK surgery.
15. IOL and implant imaging-OCT may also aid
postoperative evaluation by allowing imaging and
visualization of IOLs and implants in the eye.
16.
17. LASER THERAPY FOR DIABETIC
RETINOPATHY
Diabetic retinopathy refers to retinal changes
seen in patients with Diabetes mellitus.
With increase in the life expectancy of
diabetics,the incidence of diabetic retinopathy
has increased.
Diabetic retinopathy is a leading cause of
blindness.
TREATMENT OF DIABETIC RETINOPATHY
Intravitreal anti-VEGF drugs
Intravitreal steroids
LASER therapy
Surgical treatment
18. LASER THERAPY
ETDRS had recommended focal laser for focal
DME and GRID laser for diffuse DME.
Laser helps possibly by stimulating the RPE
pump mechanism and by inhibiting VEGF release.
Before the advert of Anti-VEGFs,which only
stabilises the vision,was the mainstay
in the treatment of DME.
However with the introduction of anti-VEGF
drugs which also improves vision,the role of
Laser therapy has become limited.
Laser therapy is performed using double
frequency YAG laser 532nm or argon green laser
or diode laser.
19. Present indicate on protocols for laser
therapy are shown below-
1.Macular photocoagulation:
It is of 2 types-
a)Focal photocoagulation:It is the
treatment of choice for focal
DME not involving the
centre of fovea.
20. b)Grid photocoagulation:It is no more the
treatment of choice for focal DME.It may
be considered only for recalcitrant cases
not responding to anti-VEGF and intra-
vitreal steroids
21. 2.Panretinal photocoagulation(PRP)or scatter
laser consist of 1200-1600 spots,each 500
micrometre in size and 0.1 sec duration.
Laser burns are applied outside the temporal
arcades and on nasal side one disc diameter
from the disc upto the equator.
The burns should one
burn width apart.
In PRP inferior quadrant of retina is first
coagulated. PRP produces destruction of
hypoxic retina which is responsible for the
production vesoformative factors.
22.
23.
24. VITRECTOMY
Vitrectomy is the surgical removal of
vitreous.
Common terms used in vitrectomy are :
Anterior vitrectomy :It refers to removal
of anterior part of vitreous.
Core vitrectomy : It refers to removal f
central bulk of vitreous.
Subtotal and total vitrectomy : In this
almost whole of the vitreous is removed.
25. TECHNIQUES OF VITRECTOMY
Anterior vitrectomy:limbal approach
This technique is employed to perform only
anterior vitrectomy.
Indications :
Vitreous loss during catract extraction
Aphakic keratoplasty
Anterior chamber reconstruction after perforating
trauma with vitreous loss
Subluxated and anteriorly dislocated lens
26. Pars plana vitrectomy :
Pars plana approach is employed to perform
anterior vitrectomy, core vitrectomy, subtotal
and total vitrectomy.
Pars plana vitrectomy (PPV) is a commonly
employed technique in vitreoretinal surgery that
enables access to the posterior segment for
treating conditions such as retinal detachments,
vitreous hemorrhage, endophthalmitis, and
macular holes in a controlled, closed system.
Indication :
Endophthalmitis with vitreous abscess.
Vitreous haemorrhages.
Proliferative retinopathies such as those
associated with diabetes, eales’s disease,
retinopathy of prematurity and retinitis
proliferans.
27. Complicated cases of retinal detachment such as
those associated with giant retinal tears, retinal
dialysis and massive vitreous traction. Presetly,
even simple cases of rhegmatogenous, retinal
detachment are managed with this technique.
Removal of intra ocular foreign bodies.
Removal of dropped nucleus or IOL from the
vitreous cavity.
Persistent primary hyperplasty vitreous.
Vitreous membranes and bands.
Macular pathology like macular hole and epi-
retinal membrane.
28.
29. PROCEDURE OF PARS PLANA VITRECTOMY
(PPV) :
Basic Setup
The basic components of a vitrectomy setup
include the following elements:
Vitrectomy machine (e.g., Alcon Constellation,
DORC EVA, Bausch + Lomb Stellaris PC).
Surgical microscope and wide-angle viewing
system (e.g., Zeiss RESIGHT, Oculus BIOM, AVI).
Infusion cannula which maintain IOP set by the
vitrectomy machine.
Endoillumination light source for visualization of
the posterior segment including vitreous and
retina.
Vitrectomy cutter (or vitrector): for vitreous
removal, aspiration, and peeling and cutting
membranes among other functions.
30. Gauges
The gauge refers to the
size of the instruments with
higher numbers corresponding
to smaller instruments.
Endophthalmitis rates twelve to
twenty-eight times higher with
25-gauge vitrectomy compared
to 20-gauge vitrectomy although
endophthalmitis rates were low
in both groups. However,subsequent
studies have found similar rates of
endophthalmitis with 20-gauge and 25-gauge
vitrectomy.
There are numerous advantages of small-gauge
vitrectomy, including:
Increased patient comfort.
Decreased corneal astigmatism.
Decreased operative times.
Decreased conjunctival scaring.
31. Dyes
The following four dyes are the
most commonly used in vitreoretinal
surgery:
Triamcinolone acetonide: available
In non-preservative-free formulation
Called Kenalog and preservative-free
formulation called Triescence,
Triamcinolone is particularly useful for
staining the vitreous gel. Injection of triamcinolone
during pars plana vitrectomy
Trypan blue: a hydrophilic dye also used for staining the
anterior capsule during phacoemulsification surgery. It
is used in vitreoretinal surgery to stain the ERM and ILM
and is FDA approved for use in ERM removal cases.
Brilliant blue: commonly used worldwide and recently
approved by the FDA in 2019, it is used primarily for
staining the ILM with minimal toxicity.
Indocyanine green: traditionally used for angiography,
indocyanine green also effectively stains the ILM.
However, at higher concentrations, it is toxic to the
retina and RPE.
32. Retinal Detachment
The principles of retinal detachment repair via pars plana vitrectomy are
to remove the vitreous gel and any vitreoretinal traction, locate and
laser any retinal tears, and insert an intraocular tamponade.
The basic steps are as follows:
Insert trocars in the pars plana (3.0-4.0mm from the limbus
depending on the lens status) typically using a beveled incision
technique.
Perform a core vitrectomy to remove the central vitreous gel. Use of
triamcinolone can aid with vitreous removal.
Induce a posterior vitreous detachment if a natural one has not
already occurred. This is often done using the vitrectomy cutter on
the aspiration only setting (i.e., the cutter function is turned off).
Perform a peripheral vitrectomy and release traction over the
detached retina, at the retinal tears, and any areas of lattice
degeneration. Again, triamcinolone can be helpful during this step.
Flatten the retina by draining subretinal fluid from a pre-existing
break or a newly created drainage retinotomy while performing a
fluid-air exchange, typically using a soft tip cannula. Alternatively,
heavy liquids such as perfluorocarbons can be injected posteriorly to
push subretinal fluid anteriorly out through a pre-existing break.
Once the retina is flattened, endolaser is then performed around the
retinal breaks.
Insert an intraocular tamponade. SF6 (lasting 2-3 weeks) and C3F8
(lasting 6-8 weeks) gas are most commonly used although there are
indications for silicone oil (lasting permanently until it is taken out) if
longer tamponade is needed or in patients who are monocular, must
fly, or cannot position.
33. Membrane Peel
To treat conditions such as epiretinal membranes, macular
holes, vitreomacular traction, tractional retinal
detachments, and proliferative vitreoretinopathy,
membrane peeling may be necessary. As with retinal
detachment surgery, the initial steps of inserting trocars,
performing a core vitrectomy, and inducing a posterior
vitreous detachment if not already present are similar. The
degree of peripheral vitrectomy performed may depend on
the clinical scenario.
Next, attention is turned to the membrane itself that
requires peeling. A different set of techniques is used here
compared to retinal detachment surgery. First, a higher
magnification and resolution lens is used, which may be
the 68-degree AVI lens, the green macular lens with the
Zeiss RESIGHT, or the DORC flat vitrectomy lens.Next, a
vital dye can be instilled in the posterior segment to
improve tissue visualization. With any membrane peel, an
initial flap must be created if not naturally present,
followed by peeling of the membrane off the retinal
surface. The initial flap can be created with Maxgrip or ILM
forceps, an MVR blade, a Tano scraper, a Finesse Flex loop,
or a pick.
34. Complications of vitrectomy
Infections.
Excess bleeding.
High pressure in the eye.
New retinal detachment caused by the surgery.
Lens damage.
Increased rate of cataract formation.
Problems with eye movement after surgery.
Change in refractive error.
There is also a risk that the surgery will not
successfully repair your original problem, if this
happens , the patient will need a repeat surgery.