There are several challenges associated with the trade cycle in e-commerce, which can affect the overall efficiency and effectiveness of the process. Some of these challenges include:
Security: One of the main challenges in e-commerce is ensuring the security of the transaction. This includes protecting sensitive data such as credit card information and personal details from theft, fraud, and other cyber threats.
Logistics: Shipping and delivery can be a significant challenge in e-commerce, particularly for products that require special handling or transportation. This includes ensuring timely delivery, tracking shipments, and dealing with returns and exchanges.
Payment processing: Payment processing can be complex, particularly for cross-border transactions involving different currencies and payment systems. It is essential to ensure that payment methods are secure, reliable, and convenient for customers.
2. UVEAL TRACT
Uvea known as middle
vascular coat of eyeball.
Anterior to posterior it can
be divided into three parts---
Iris
Ciliary body
Choroid
Note– Uvea is a Greek
word meaning Grapes.
3. IRIS
Anterior part of the uveal tract.
Forms diaphragm like structure in front of lens.
Center of iris has an 3-4 mm aperture called Pupil.
At periphery it is attached to the anterior surface of ciliary
body.
Divides the space between the cornea and lens into anterior
and posterior chamber.
4.
5. TOPOGRAPHY OF IRIS
Average diameter of the iris is 10 to 11 mm.
The thickness of iris root is approximately 0.5
mm.
It is thickest at collarette, which is located
approximately 1.5 mm from the pupillary
margin
It is thinnest at iris root, the part of iris which
joins with the ciliary body
6. EMBRYOLOGY
Both layer of epithelium is derived from marginal region of
optic cup. (Neuroectoderm)
Sphincter and dilator pupillae muscle derived from anterior
epithelium . (Neuroectoderm)
Stroma and vessels developed from vascular mesoderm
present anterior to optic cup.
7. MACROSCOPIC APPEARANCE
Anterior surface—
Divided into cilary and pupillary zone by zigzag line called
collarette.
It is the thickest region of the iris which lies about 2 mm
from the pupil margin.
8. Cilliary zone-
It extend from the collarette to iris root.
There are some depressions or pit arranged in
rows present in this area known as crypts.
Crypts are found in two locations. Those
present near collarette are relatively larger and
known as Fuchs’s crypt and few are seen in
periphery of the iris
Pupillary Zone-
It lies between the collarette and pigmented
pupilary frill
It is 1.6 mm wide,relatively smooth and flat.
9.
10. POSTERIOR SURFACE
Posterior surface of
the iris is much more
uniform.
Posterior surface of
the iris is darker than
the anterior surface and
shows numerous radial
contraction folds.
12. 1.Anterior limiting layer :
It lines the iris and is the anterior most condensations of iris
stroma.
The layer consist of mainly fibroblasts and melanocytes.
Previously, this layer is known as ENDOTHELIAL LAYER .
This layer is mainly responsible for the colouring action of iris.
2. Iris stroma:
Iris stroma forms the main bulk of iris tissue and contains
sphincter pupillae, dilator pupillae muscles, vessels and nerves.
3. Anterior epithelium layer :
It is the anterior continuation of the pigmented epithelium of
retina and ciliary body.
4. Posterior pigmented epithelium layer-
Anterior continuation of the non- pigmented epithelium of the ciliary body
and the sensory retina
13.
14. CILIARY BODY
It is the anterior portion of the uveal tract , which is
located b/w the iris and the choroid.
middle part of vascular coat of eyeball.
Triangular in shape.
Inner side of triangle is divided into two parts.
The anterior portion - pars plicata
The posterior portion-pars plana
The outer side of triangle lies against the
sclera.
composed of muscles , vessels and epithelium.
15.
16.
17. EMBRYOLOGY
Both epithelial layer of ciliary body develop from
the anterior part of the two layers of optic
cup.(neuroectoderm)
Stroma of the ciliary body , ciliary muscle and blood
vessels are developed from the vascular layer of
mesenchyme surrounding the optic cup.
18.
19. MICROSCOPIC STRUCTURE
🞭 Microscopically ciliary body consist of five layers.
o Supraciliary lamina.
o Stroma.
o Layer of pigmented epithelium.
o Layer of non pigmented epithelium.
o Internal limiting membrane.
20. Supraciliary lamina –
outermost condensed part of the stroma consist of pigmented
collagen fibres.
Anteriorly become continues with the anterior limiting
membrane of iris.
posteriorly, it is the continuation of the suprachoroidal lamina.
Stroma—
Consist of connective tissue of collagen and fibroblast.
Ciliary muscle, vessels, nerves and cells are embedded in
stroma.
Layer of pigmented epithelium-
Forward continuation of the retinal pigmented epithelium.
Anteriorly become continues with the anterior pigmented
epithelium of iris.
21. Layer of non pigmented epithelium-
Forward continuation of sensory retina.
Continues anteriorly with the posteriorly pigmented
epithelium of iris.
Internal limiting membrane-
Forward continuation of the internal limiting membrane of
the retina.
Lines the non-pigmented epithelial layer.
22. CILIARY PROCESS
🞭 Finger like projection from the pars plicata part of the
ciliary body.
🞭 They are white in color
🞭 Process is lined by two layer of epithelial cell .
🞭 It contain blood vessels and loose connective tissue
🞭 these process are the site of aqueous production.
🞭 Each process is about 2 mm long and 0.5 mm in
diameter.
🞭 They are about 70 to 80 in numbers.
23.
24. CILIARY MUSCLE
Occupies most of the outer part of the ciliary body.
These are non striated muscle having three parts
1. Meridional fibers- Help in aqueous outflow.
2. Circular fibers
3. Oblique fibers
- Help in accommodation.
- Help in Aqueous outflow.
Ciliary muscle is supplied by parasympathetic fibers
through the short ciliary nerves.
Action- Main action is to slacken the suspensory
ligament of the lens and thus help in
accommodation.
25.
26.
27.
28.
29. EMBRYOLOGY
Mainly derived from the inner vascular layer
of the mesenchyme that surrounds the optic
cup
Melanocytes of choroid originate from the
neural crest.
30. MICROSCOPIC STRUCTURE OF
CHOROID
Choroid consist of four layers.
Suprachoroidal lamina.
Stroma.
Choriocapillaris.
Bruch's membrane.
31.
32. 1.Suprachoroid lamina (lamina fusca):
Thin membrane of condensed collagen fibers,
melanocytes and fibroblast.
It consist of potential space between sclera and choroid
known as supra choroidal space.
The potential space contains the long posterior ciliary arteries
and nerves.
2. Choroidal stroma:
Consist of loose collagenous tissue with some elastic and
reticular fibers.
Contain pigmented cells and plasma cells.
It forms the main bulk of the choroid.
It consist of two types of vessels Medium vessels and large
vessels
33. 3. Layer of Choriocapillaris
It nourishes the pigmented epithelium and outer layer of sensory
retina.
Choriocapillaries contain a basement membrane.
Receive blood from medium and large vessels of stroma.
The capillary walls are fenestrated and contains pericytes
4. Bruch's membrane:
innermost layer of choroid having thickness 2-4 mm.
Multilayered structure lies between the choriocapillaris and
pigmented epithelium of retina.
It consist of five layers:-
• Basement membraneof retinal pigmentedepithelium
• Inner collagenfibers
• Middleelasticfibers
• Outer collagenfibers
34.
35.
36. BLOOD SUPPLY OF UVEAL TRACT
🞭 The uveal tract is supplied by three sets of artery.
Short posterior ciliary artery- Arises as two trunks from the
ophthalmic artery .
It pierce the sclera around the optic nerve and supply the
choroid in a segmental manner.
Long posterior ciliary artery-- two in number nasal and temporal
.
Pierce the sclera obliquely on medial and lateral side of the
optic nerve and supply the ciliary body.
Anterior ciliary artery– Derived from muscular branches of
ophthalmic artery.
7 in numbers– 2 each of superior, medial, inferior rectus
muscle and one from lateral rectus muscle
these artery gives branches to sclera , limbus and conjunctiva.
37.
38. NERVE SUPPLY
The iris receives its sensory and autonomic
nerve supply from the long and short ciliary
nerves.
The long ciliary nerves are branches of the
nasociliary branch of the ophthalmic division
of the trigeminal nerve. These fibers
innervate the dilator pupillae.
• The short ciliary nerves arise from the
ciliary ganglion and contain postganglionic
parasympathetic nerve fibers.
The parasympathetic innervates the
sphincter pupillae.
39. The choroid is innervated by the long and
short ciliary nerves.
The long ciliary nerves are branches of the
nasociliary nerves, a branch of the
ophthalmic division of the trigeminal nerve.
(sensory & parasympathetic) –
The short ciliary nerves arise from the ciliary
ganglion and carry parasympathetic fibers
and sympathetic fibers.
The ciliary muscle is innervated by the
postganglionic parasympathetic fibers
derived from the oculomotor nerve; The nerve
fibers reach the muscle via the short ciliary
nerves.
40.
41. UVEITIS
Also known as Iridocyclitis.
Inflammation of uveal tissue.
Common cause of blindness.
Associated with systematic autoimmune disease.
Symptoms and signs
Ciliary flush
Burning of the eye
Redness of the eye
Blurred vision
Photophobia or sensitivity to
Light.
Irregular pupil.
42. ENDOPHTHALMITIS
It is an inflammation of the internal coats of the eyeball
It is a possible complication of all intraocular surgeries,
particularly cataract surgery, with possible loss of vision and the eye
itself.
CAUSES-
Bacterial and fungal infection
penetrating trauma
allergic reaction
Symptoms-
severe pain
loss of vision
redness of the conjunctiva
Photophobia
Management-
Topical therapy
Subconjunctival infections
Intravitreal injection.
43. PANOPHTHALMITIS
Inflammation of the whole eyeball including tenon’s
capsule.
Eyeball is filled with pus
Uveal tract is infiltrated with inflammatory cells like WBC.
Symptoms-
Ocular pain
Headache
Complete loss of vision
Swelling of eyes.
Management-
anti-inflammatory and analgesics should be started
immediately.
use broad spectrum of antibodies to prevent further
spread of infection.