Aphakia and its causes. Correction of Aphakia. Advantages and disadvantages of different corrections. Surgeries and related signs and symptoms of aphakia. Complications related to Aphakia.
Aphakia and its causes. Correction of Aphakia. Advantages and disadvantages of different corrections. Surgeries and related signs and symptoms of aphakia. Complications related to Aphakia.
. Introduction Biomicroscope derives its name from the fact that it enables the practitioner to observe the living tissue of eye under magnification. It not only provides magnified view of every part of eye but also allows quantitative measurements and photography of every part for documentation.
3. • The lamp facilitates an examination which looks at anterior segment, or frontal structures, of the human eye, which includes the –Eyelid –Cornea –Sclera –Conjunctiva –Iris –Aqueous –Natural crystalline lens and –Anterior vitreous.
4. Important historical landmarks De Wecker 1863 devised a portable ophthalmomicroscope . Albert and Greenough 1891,developed a binocular microscope which provided stereoscopic view. Gullstrand ,1911 introduced the illumination system which had for the first time a slit diapharm in it Therefore Gullstrand is credited with the invention of slit lamp.
Intraocular Lens (IOL) power calculation is a crucial step in cataract surgery and certain refractive surgeries like phakic IOL implantation. The goal is to determine the appropriate power of the IOL to be implanted into the eye, ensuring that the patient achieves their desired postoperative visual outcome. Several formulas and methods are available for IOL power calculation, and the choice of formula depends on various factors, including the patient's eye measurements and the surgeon's preference. Here, we describe the basic principles and some commonly used formulas.
Ocular Biometry:
Ocular biometry is the process of measuring various dimensions of the eye, primarily the axial length, corneal power, and anterior chamber depth. These measurements are essential for accurate IOL power calculation and achieving the desired post-surgical refractive outcome. Here are the key components of ocular biometry:
Axial Length: This measurement determines the overall length of the eye, from the cornea's front surface to the retina's back surface. Axial length is a critical factor in IOL power calculation because it helps determine the eye's focusing power.
Corneal Power: The cornea is the transparent front surface of the eye, and its curvature affects the eye's refractive power. Corneal power is typically measured using techniques like keratometry or corneal topography. It helps account for the eye's astigmatism and assists in selecting the appropriate IOL.
some basic notions on how they are measured is explored here.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
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We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
2. Parts include Anterior chamber
are:- (From posterior to anterior)
Pupil. Visible with the gonioscope if dilated.
Iris. Colour varies between individuals.
Ciliary body. Longditudinal muscle. Colour varies
between individuals - may be pale brown, grey or dark.
Scleral spur. Protrusion of sclera into anterior
chamber. Attached to ciliary body posteriorly and
trabecular meshwork anteriorly.
3. Parts include Anterior chamber
are:- (From posterior to anterior)
Trabecular meshwork. Multilayered network of
fenestrated lamellae and endothelial cells draining aqueous
into Canal of Schlemm which may visible when full of
blood (e.g. in hypotony or when excess force applied to
sclera during gonioscopy).
The multi-layers include
1) Anterior Trabecular meshwork
2) Posterior Trabecular meshwork
Most of the drainage occurs via the posterior, more
pigmented, portion of the trabecular meshwork. There are
variations in colour but usually grey with varying degrees of
pigmentation
4. Parts include Anterior chamber
are:- (From posterior to anterior)
Schwalbe's line. Delineates the anterior edge of the
trabecular zone and represents the termination of
Descemet's membrane. Very fine glossy white line.
5. Reasons for anterior chamber
examination include:
To rule out anterior segment inflammation (e.g.
anterior uveitis )
To detect eyes at risk from angle closure
To differentially diagnose open angle, closed angle,
primary and secondary glaucoma.
To assess eyes at risk from developing anterior
chamber sequelae to other disease e.g. diabetes
mellitus, CRV occlusion
6. Assessment of anterior chamber
include: Assessment of anterior chamber angle (ACA):-
anatomical angle created by the root of the iris and the
peripheral corneal vault.
Assessment of anterior chamber depth (ACD):-
Aqueous-containing space of the eyeball between the
cornea and the iris.
7. Methods that can assess the ACA
and ACD in clinical practice are: Pen torch method
Smith’s method
Van Herrick’s technique
Split limbal technique
Optical coherence tomography
Gonioscopy
8. Pen Torch method: Shine a pen torch into the pt’s eye from the temporal
canthus such that the pen torch lies in the same plane
of eye.
In the case of a deep anterior chamber, the iris lies flat
and the whole iris will be illuminated.
In the case of a very shallow anterior chamber the iris
lies forward, blocking some of the light and very little
of the iris is illuminated.
9. Based on the amount of eye illuminated the ACD can
be graded.
Figure 1 :Grading of anterior chamber angle/depth using the pen
torch method
10. Smith’s method: Is a quantitative method of measuring the ACD.
It is carried out using a slit lamp with the observation
system directly in front of the patient’s eye and the
illumination system at an angle of 60° to the temporal
side.
A beam of approximately 1.5mm thickness, with its
orientation horizontal, is placed across the cornea.
Strain tear film with the fluroscein (for an easy
assessment)
11. A second horizontal beam is then seen in the plane of
the crystalline lens.
The length of the beam is adjusted until the beams on
the cornea and crystalline lens just appear to meet
The length of the beam is read directly from the slit
lamp and this number is multiplied by 1.34 to
calculate the ACD.
12. Van Herrick’s technique: Common quantitative method of assessing the size of
the ACA using the slitlamp biomicroscope.
It involves comparing the size of an optic section width
on the cornea to the gap between the section and the
reflection on the iris when a beam is trained just
within the limbus at an angle of 60°.
It from the limbus the more the angle will be
overestimated. An angle of 60° should be used
consistently to allow for standardisation of
measurements.
13. Van Herrick’s technique: The AC angle width used to be graded on a scale of
grade 0 (closed) to 4 (wide open).
14. Split limbal technique: To estimate the superior and inferior angles the split
limbal technique can be used.
In this technique the slit lamp is used to provide the
illumination.
With the illumination in the click position, a vertical
slit should be placed across the superior ACA
at 12 o’clock.
Observe the arc of light falling on the cornea and iris.
15. Split limbal technique: The angular separation seen at the limbal corneal
junction is an estimation of the anterior chamber
angle depth in degrees.
16. Optical Coherence
Tomography(oct)
Uses low coherence interferometry to obtain cross-
sectional images of the ocular structures.
To image the anterior segment, longer wavelength
light (1,310nm) is used.
Anterior segment OCT can be used to take
measurements of the angle.
17. Gonioscopy: The gold standard for ACA assessment is gonioscopy.
Use of a slit lamp and gonio-lens.
Allow direct visualisation into the ACA.
To carry out gonioscopy, the cornea is anaesthesised
using topical anaesthetic.
With gonioscopy any abnormalities within the angle
eg, pigment deposition, neovascular growth etc. can be
detected
18. Gonioscopy: The structures visible in a wide angle are (from iris to
cornea)
(a) The ciliary body (CP): this appears slightly darker
than the iris itself,
(b) the scleral spur (SS): a white band just above the
ciliary body,
(c) the trabecular meshwork (TM): this can be a
whitish-grey or pink colour, and
(d) Schwalbe’s line (SL):
19. Structures Visible in Gonioscopy
The visible structures of the anterior chamber angle
during gonioscopy. CP = ciliary body; SS = scleral
spur; TM = trabecular meshwork; SL = Schwalbe’s line
21. Conclusion
A full assessment of the ocular health should include
some examination of the ACA and/or ACD.
The depth of the anterior chamber naturally decreases
with age due to the increase in size of the crystalline
lens and with this decrease comes an increased risk of
narrow and closed angle glaucoma.