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Anatomy of Uvea

Text + Graphic: Dr. Parthopratim Dutta Majumder


Uvea is the middlUvea e vascular coat of eye ball. From anterior to posterior, the uvea or uveal tract can be divided into three parts- Iris,Ciliary body and choroid. The name “uvea” has originated from Latin word grape. Why a grape? If the stem is removed from a grape, the hole looks like the pupil and the grape the eyeball.

 

 

 

Iris :uveatopography

Iris is the anterior most part of the uveal tract. It is a thin and circular structure which forms a diaphragm like structure in front of the crystalline lens. The word “iris” has originated from a Greek word. In Greek mythology the iris is the name of Greek goddess of rainbow.

The diaphragm formed by iris contains a central aperture known as pupil. The location of the pupil is not exactly central, its little nasal to the center. The pupil determines the amount of light entering the eye. The normal size of pupillary aperture is 3-4 mm. Details on pupil will be discussed in chapter "Pupil".

Iris is attached to the middle of anterior surface of ciliary body. The iris divides the space in front of the lens into anterior chamber and posterior chamber.

Topography of IRIS: Average diameter of the iris is 10 to 11 mm. It is thickest at collarette, which is located approximately 1.5 mm from the pupillary margin and thinnest at iris root, the part of iris which joins with the ciliary body. The thickness of iris root is approximately 0.5 mm.

 

Note:

During blunt trauma, damage to iris occurs most commonly at the iris root, where the iris rips away from the ciliary body

Anterior surface of the iris is divided into a pupillary zone and a ciliary zone by a circular ridge, located 1.5 mm away from pupillary margin, called collarette (also known as iris frill).

Iris anatomy

Pupillary Zone: Pupillary zone extends from pupillary margin to collarette. Pupillary zone is relatively flat. Pupillary margin is marked by a dark border, known as pupillary ruff. Pupillary ruff is the anterior termination of the pigmented layer, which lines the posterior surface of iris.

Ciliary Zone: Ciliary zone of iris extends from 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.

Note:

Collarette is the site of foetal pupillary membrane attachment.

 

posterior surface of iris

Posterior surface of Iris: 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. However circular folds are also seen.

 

 

In laser iridotomy, the opening is created in areas of iris crypts, as it requires less amount of energy in these thinnest areas of iris thickness.

 

Microscopic structure of Iris :

1. Anterior limiting layer :Anterior limiting layer lines the iris and is the anterior most condensations of iris stroma. The layer consist of mainly fibroblasts and melanocytes. These cells are arranged in a meshwork-fibroblasts are located on the surface and melanocyte beneath them.

The colour of iris depends on the thickness of the layer and melanocyte dispersed in anterior limiting layer. The color of the iris is largely determined by three main variables: (1) the density and structure of the iris stroma, (2) the pigment epithelium, and (3) the pigment content (granules) within the melanocytes of the iris stroma

Heterochromia of iris (Greek: heteros 'different' + chroma 'color'):  is of two kinds. In complete heterochromia, one iris is a different color from the other. In partial heterochromia or sectoral heterochromia, part of one iris is a different color from its remainder.

Anterior limiting layer is absent at the areas of crypts and very thin at the contraction furrows.

Clinical Note

Neovascularisation of iris occurs in anterior limiting layer.
 
2. Iris stroma: Iris stroma forms the main bulk of iris tissue and contains sphincter pupillae, dilator pupillae muscles, vessels and nerves

iris anatomy

Cells in iris stroma:

Fibroblasts are the most prominent cells in iris stroma. These cells are located in close association with blood vessels, muscles, and nerves. Melanocytes can be found around the adventitia of blood vessels. Melanocytes contain mitochondria, smooth and rough endoplasmic reticula, free ribosomes and melanin granules in various stages of development. They have long processes with the help of which they form plexuses with fibroblasts and adjacent melanocytes.

Pigment dispersion syndrome: Pigment dispersion syndrome is a bilateral condition characterized by the liberation of pigment granules from the iris pigment epithelium. It Is caused by the mechanical rubbing of the posterior pigment layer of the iris against lens zonules as a result of excessive posterior bowing of the mid-peripheral portion of the iris. However pigment epithelium itself may be abnormally susceptible to pigment shedding.

pigment dispersion glaucoma

Clump  cells (also called  clump cells of Koganei ) are  large,  round, pigmented cells, located  in  the  pupillary  portion  of  the  stroma,  mainly  near  the  sphincter muscle . There are two types of clump cells. Type I cells are numerous and believed to be “altered macrophages” and they act as scavengers of free pigments, present within the iris. Type II cells are less in numbers and are thought to represent smooth muscle cells in arrested stages of development.

Muscles in iris stroma:

The sphincter pupillae muscle is a circular muscle, 0.75 to 1 mm wide, composed of smooth-muscle cells. The muscle is 0.1 to 1.7 mm in thickness and is considerably thicker than the dilator papillae.It encircles the pupil and is located in the pupillary zone of the stroma. The sphincter muscle is firmly adherent to the surrounding stroma of iris. Sphincter muscle is composed of spindle-shaped cells that are oriented parallel to the pupillary margin, so, contraction of the sphincter causes the pupil to constrict (a process known as miosis). The muscle is innervated by the parasympathetic system.

Note:

The sphincter pupillae retains its function even if severed radially because of its unique distribution of fibres.

 

The dilator pupillae muscle extends from  the  iris root  to a point in the stroma below the midpoint of the  phincter. A dense band of connective  tissue separates the sphincter and dilator muscles from each other . However near the  termination  of  the  dilator  muscle,  small  projections  insert  into  the sphincter. Because  of the radial arrangement of the fibres of the muscle, contraction of the dilator pupillae muscle pulls the pupillary portion  toward  the  root,  thereby  enlarging the the size of pupil ( a process ka mydriasis). The dilator pupillae muscle is sympathetically innervated. (Read anterior pigment epithelium of iris also).

Blood vessels in iris stroma:

Iris vessels include arterioles, venules, and capillaries. The iris arteries are branches of major circle of the iris, located in the ciliary body near the iris root. The iris vessels usually follow a radial course from the iris root to the pupil margin. These vessels are surrounded by a dense network of collagenous fibrils which is embedded in to the collagen network of the stroma. Such arrangement of collagen network prevents the iris vessels from kinking  and  compression  during  the extensive  iris movement  during constriction and dilatation of pupil. Iris veins have very thin walls consisting of endothelium surrounded by a thin layer of collagen. Capillaries are formed by a single layer of unfenestrated epithelium, which forms a part of the blood-aqueous barrier.

Nerves in iris stroma:

Iris nerves are usually unmyelinated, however some nerves are found be enclosed by Schwann cells.

3. Anterior pigment epithelium: The cells in anterior pigment epithelial layer of the iris have two distinct portions.
Muscular basal portion anteriorly (lies next to stroma): composed of elongated, contractile, smooth muscle fibres. These muscle fibers extend into the stroma, forming three to five layers of dilator muscle fibers joined by tight junctions
Epithelial apical portion posteriorly (lies above posterior pigment epithelium of iris): composed of pigmented cuboidal epithelium where cells are joined by  tight junctions and desmosomes.
The epithelial apical portion of anterior pigment epithelium is in close apposition with the apical surface of the posterior pigment epithelium. Similar kind of  apex-to-apex arrangement is to seen between the pigmented and nonpigmented epithelium of ciliary body.  The cause of this apex-to-apex arrangement is due to their common embryologic precursor, the optic cup. The anterior iris epithelium continues posteriorly as  the pigmented epithelium of the ciliary body.

4. Posterior pigment epithelium of iris: Posterior pigment epithelium is the second layer of pigmented epithelium situated posterior to the iris stroma. The cells are rectangular or pyramidal in shape with round cell nucleus and their cytoplasms contain large pigment granules. The cells of the posterior pigment epithelium are more heavily pigmented than anterior pigment epithelium. The cells are joined to each other by maculae adherens and occludens. These cells rest on a thin layer of basement membrane situated posteriorly.

Ciliary body

Ciliary body is the middle part of the uveal tract . It is a ring (slightly eccentric ) shaped structure which projects posteriorly from the scleral spur, with a meridional width varying from 5.5 to 6.5 mm.  It is brown in colour due to melanin pigment.  Anteriorly it is confluent with the periphery of the iris (iris root) and antericilliarybody anatomyor part of the ciliary body bounds a part of the anterior chamber angle. Posteriorly ciliary body has a crenated or scalloped periphery, known as ora serrata, where it is continuous with the choroid and retina. The ora serrata exhibits forward extensions,known as dentate process, which are well defined on the nasal side and less so temporally. Ciliary body has a width of  approximately 5.9 mm on the nasal side and 6.7 mm on the temporal side.

cilliarybody anatomyExtension of the ciliary body : On the outside of the eyeball, the ciliary body extends from a point about 1.5 mm posterior to the corneal limbus to a point 6.5 to 7.5 mm posterior to this point on the temporal side and 6.5 mm posterior on the nasal side.

 

 

 

Parts of ciliary body: Ciliary body, in cross section, is a triangular structure ( in diagram it can be compared as ∆ AOI). Outer side of the triangle (O) is attached with the sclera with suprachoroidal space in between. Anterior side of the triangle (A) forms part of the anterior & posterior chamber. In its middle, the iris is attached. The inner side of the triangle (I) is divided into two parts. The anterior part (2 mm) with finger like processes is known as pars plicata (corona ciliaris) and posterior smooth (4 mm) is known as pars plana (orbicularis ciliaris).

Pars plicata: The pars plicata is the portion of ciliary body which contains the ciliary processes. Ciliary processes are the finger like projections , which  extend  into the posterior  chamber. The  regions between ciliary processes are called valleys of Kuhnt. They are approximately  70  to  80  in numbers. A ciliary process measures approximately 2 mm  in  length, 0.5 mm  in width, and 1 mm in height.

Pars plana: As discussed earlier, pars  plana  is  the  flat or smooth  part  of  the  ciliary body. It terminates at the ora serrata, which is the transitional zone between ciliary body and choroid. Histologically, the pars plana consists of a double layer of epithelial cells: the inner, nonpigmented epithelium, which is continuous with neurosensory retina; and the outer, pigmented epithelium, which is continuous  with the retinal pigment epithelium (RPE) .

The pars plana is a relatively avascular zone, which is important surgically in the pars plana approach to the vitreous space.The pars plana provides surgical access to the vitreous and retina.

 

Ora serrata: the transition zone:

The ora serrata can be termed as the anterior border of the neurosensory retina. Ora serrata shows forward extensions into the retina, which are well defined in the nasal side and less so temporarily. Dentate processes are “teeth-like” extensions of neurosensory retina in to pars plana. There are approximately 20 to 30 dentate processes per eye. Ora bays are rounded extensions of the pars plana.

 

Topographically, ora serrata corresponds to the insertion of the medial and lateral rectus muscles.

 

Lens and ciliary body:

The zonules course from ciliary body to the lens. Some of these zonular fibers insert into the internal limiting membrane of the pars plana region and travel forward through the valleys (valleys of Kuhnt) between the ciliary processes. It can be mentioned here that the distance between equator of lens and ciliary body is approximately 0.5 mm.

Layers of ciliary body:

From inside to outside (from sclerad to vitread ), ciliary body consists of following four layers.

1. Ciliary epithelium:

Ciliary epithelium consists of two layer which covers the inner surface of the ciliary body ( don't confuse !! from vitreous side, it is external side).these two layers are  representative of two layers of optic cup embryologically.

1A. Non pigmented epithelium (NPE) of ciliary body :

NPE of ciliary body extends from iris root to ora serrata. It begins as a continuation of posterior pigmented epithelium of iris near iris root. In nonpigmented epithelium of ciliarybody, cells become smaller and there is significant decrease in melanin granules in the cells . At pars plicata, cells are cuboidal and they gradually become columnar with increasing ages. At ora serrata, the NPE continues as sensory retina.

The internal limiting membrane is secreted by the basal lamina of the non-pigmented epithelium on its basal surface, which is on the vitreal side. It is the continuation of  inner basement membrane of the iris and continues posteriorly as inner  basement membrane of retina. It gives origin to parts of the suspensory lens ligament.

cilliary epithelium1 B. Pigmented epithelium of ciliary body:

The cells of the pigmented epithelium are 8 to 10 microm wide wide and contain large pigment granules. These pigment granules are three to four times larger than those of the choroid and retina. These cells are rich in organelles and are very active metabolically .
The cells of pigment epithelium secretes basement membrane which continues posteriorly with the  retinal pigment epithelium (RPE).

Ciliary epithelium : metabolic activity

The cells of both the ciliary epithelium have a greater number of mitochondria  and thus they have a higher degree of metabolic activity, with a significant role in the active secretion of aqueous humor.
As the name suggests, pigmented epithelium cells have  large melanosomes which occupy almost whole of the cytoplasm. It has to be kept in mind that because of the unique apex to apex configuration of the cells of non-pigmented and pigment epithelium of ciliary body, basement membrane of the non-pigmented epithelium faces the posterior chamber where as basement membrane of the pigmented epithelium of ciliary body rests on the stroma of the ciliary body .(See Ciliary Process below)

2. Ciliary stroma:

Ciliary stroma consists of bundles of loose connective tissue. Ciliary stroma contains blood vessels, nerves and ciliary muscle. Ciliary stroma continues anteriorly with iris stroma and continues posteriorly with choroidal stroma after thinning out at pars plana.

Blood vessels in ciliary stroma: Major arterial circle of iris

Major arterial circle of iris, formed by the anastomosis of long posterior ciliary arteries and anterior ciliary arteries , is located in ciliary stroma near iris root just in front of circular portion of ciliary muscle. Ciliary stroma also consists of numerous capillaries which are fenestrated and large in size. The capillaries are more in numbers in ciliary processes,  making them the most vascular organ of the eye.

Muscle in ciliary stroma: ciliary muscle

Ciliary muscle is a nonstriated or smooth muscle primarily situated in the anterior two thirds of the ciliary body stroma. The muscle has three parts

  1. Outer longitudinal or meridional portion (Brücke's muscle): This is the most external part (nearest to the sclera) of the ciliary muscle. This part of the muscle is v shaped, the base of the v is attached to the scleral spur and limbs are inserted into the stroma of choroid.
  2. Middle oblique portion (also called reticular or radial):  This part of the muscle also originates from the scleral spur and the muscle fibres are attached to the collagenous substances near ciliary processes.
  3. Inner circular portion (Müller's muscle): Here the muscle bundles are circular in shape ( that's why it is also called annular part of ciliary muscle) and act as a sphincter. It lies close to the periphery of lens and embedded in ciliary stroma near the major arterial circle of iris.

cilliarymusclesContraction of the ciliary muscle, especially of the longitudinal and circular fibers, pulls the ciliary body forward during accommodation.Read about the accomodative power of crystalline lens .This forward movement of ciliary body relieves the tension in the suspensory lens ligament (zonules), making the elastic lens more convex and there by helps the eye in accommodation by increasing the refractive power of the lens.

Ciliary muscle is innervated by the autonomic nervous system, parasympathetic postganglionic fibres derived from the oculomotor nerve. The nerve fibres reaches the muscle via short ciliary nerve. The  parasympathetic stimulation activates the muscle for contraction, whereas sympthetic innervation likely has an inhibitory effect.

Parasympathetic fibers, coming from the Edinger Westphal nucleus with the oculomotor nerve, are mixed with nerve fibres from the ciliary ganglion and form a plexus in the ciliary muscle.

Kindly note that while classifying the different parts of ciliary muscle, the term outer is used as external, meaning nearer to sclera or to the outer side

 

Sympathetic fibers from the cervical sympathetic trunk, synapse in the superior cervical ganglion, and run to the ciliary muscle via the long ciliary nerve. The sensory fibers, coming from the nasociliary branch of the trigeminal nerve, also run in the long ciliary nerve to the ciliary body and terminate in the ciliary muscle.

Supraciliary lamina:

Supraciliary lamina is the outermost layer of ciliary body which lies adjacent to the sclera. It is composed of loose connective tissue with collagen strands, fibroblasts and melanocytes. Some of the collagen strands merge with scleral collagen. Because of the lamellar arrangement of connective tissue in this area, supra ciliary lamina acts as a potential space. Thus it also helps aqueous humor to exit by the unconventional pathway .

Ciliary body detachment occurs through supraciliary lamina

 

Ciliary process :

Ciliary processes are finger like projections seen in pars plicata of ciliary body. Ciliary processes are approximately 70 to 80 in numbers in each eye and extend into the posterior chamber, and the regions between these ciliary processes are called valleys of Kuhnt. Zonules of lens (suspensory ligaments of lens) are inserted in these valleys. Each of these ciliary processes are 2 mm in length and 0.5 mm in diameter. The ciliary process lies 0.5 mm from the periphery(equator) of the crystalline lens. The ciliary processes are white whereas the valleys of Kuhnt are dark in colour.

Parsplana

Ciliary processes increase the surface area of pars plicata, which is approximately 6 square centimetre, approximately five times the surface area of corneal endothelium.

 

 

 

CilliaryprocessMicroscopic structure of a ciliary process can be discussed as below.

1. Capillaries: Each ciliary process contains a network of capillaries in its centre. These capillaries consist of a thin endothelium which is characterised by numerous fenestrations or pores.

2. Stroma: Connective tissue stroma is very thin and consists of ground substances which include mucopolysaccharides, proteins, collagen connective tissue fibrils, mainly collagen type III etc.

3. Ciliary epitheliums: Two epithelia namely pigmented and nonpigmented epitheliums are arranged in apex to apex configuration. Outer pigmented epithelium consists of mainly cuboidal cells which contain numerous melanin granulosomes. This outer pigmented epithelium has an atypical basement membrane which is situated on the stromal side of ciliary process. This atypical basement membrane is a continuation of Bruch's membrane of choroid. The nonpigmented epithelium consists of columnar cells which contain numerous mitochondria, endoplasmic reticulum etc. The basement membrane of the nonpigmented epithelium faces aqueous humour and is also called internal limiting membrane.

 

 

A variety of intercellular junctions are involved in connecting adjacent cells of two layers of ciliary epithelium and also the their apical surfaces. These include gap junctions, puncta adherentia, desmosomes etc.

Blood supply of ciliary process:
Long posterior ciliary artery, a branch of ophthalmic artery, pierce the globe near the optic nerve and run up to ciliary body to form major arterial circle, which is formed with the anastomosis of of anterior ciliary arteries. Several branches from major arterial circle supply ciliary processes. These are mainly pre capillary arterioles and they divide in to network of capillary plexuses in each of the ciliary processes. These vessels drain in to choroidal and intrascleral veins.

 

The pre capillary arterioles supplying the ciliary processes have sphincters which is may be responsible for the auto regulation  of blood supply to the tissue

Choroid
Choroid is a thin but highly vascular membrane lining the inner surface of sclera. It extends from anteriorly ora serrata to the optic nerve posteriorly. It has a rough outer surface which is attached to sclera at the optic nerve and at the exit of the vortex veins. The smooth inner surface of choroid is attached to the retinal pigmented epithelium (RPE).Choroid becomes continuous with pia and arachnoid at the optic nerve. Choroid is normally 100-220 µm thick ; thickness is highest at macula 500- 1000 µm.

Choroidal thickness increases in intraocular inflammation.
The smooth configuration of choroid can be observed ophthalmoscopically in choroidal detachment

 

Microscopic structure of choroid:

choroid

Choroid is composed predominantly of blood vessels surrounded by melanocytes, nerves and  connective tissue. Choroid can be divided into the following layers histologically:

1. Suprachoroid lamina (lamina fusca):

Suprachoroid lamina is consist of collagen fibres, fibroblasts and melanocytes . Suprachoroid lamina overlies a potential space between sclera and choroid known as suprachoroidals space. This potential space contains the long posterior ciliary arteries and nerves.

2. Choroidal stroma:

Unlike tissues like iris, where stroma occupies a major part of the tissue,choroidal stroma is sparse as major bulk of choroid is made up of choriocapillaries. The choroidal stroma is a pigmented loose connective tissue which contains following elements:

Vessels: The vessels of choroid are arranged in layers. Larger vessels are located  on the outer side and the layer is called Hallers layer. The vessels of this layer branch and form medium sized vessels. The layer of these medium sized vessels is known as Sattler's layer.  These vessels again branch forming smaller vessels and capillaries. Venues of choroid drain into veins which ultimately drain into four vortex veins (one from each quadrant of the eye).

 

Choroidal veins are devoid of valve

 

Nerves:

Cells: Melanocytes, fibrocytes, mast cells and plasma cells are the predominant cells found in choroidal stroma. Melanocytes are distributed heavily in outer part of the layer and near optic disc. Among the non pigmented  cells, fibroblasts are the most common.

Connective tissue: Collagen fibrils are dispersed in all directions and surround the blood vessels

3. Layer of Choriocapillaris:

It is a single layer of capillaries which are larger than the normal capillaries of our body. It has been estimated that the lumen of these capillaries are three to four times larger than normal capillaries. The capillary walls are fenestrated and contains pericytes. Choriocapillaries contain a basement membrane.

Pericytes found in capillaries are also known as cells of Rouget. They have the contractile functions and are believed to alter the blood flow in capillaries.

 

Choriocapillaries are thickest and most abundant in submacular area. Experimentally it has been found that choriocapillaries are arranged in a lobular structure where the feeding arterioles are in the centre and draining veins are in the periphery.

Choroidal circulation: tits bits

  1. Choroidal circulation constitutes 85% of the blood circulation of the eye.
  2. Choroidal blood flow is higher than that in tissues like retina and brain.
  3. Choroidal blood-flow ranges from 800 to 2000 mL/min/100 g of tissue.
  4. Choroid provides the metabolic requirements of the full retinal thickness only in the macular region.
  5. In embryonic life, choroid serves as an additional site for the erythropoiesis.

4. Bruch's membrane:

bruchs membrane

Bruch's membrane is the innermost layer of choroid and it is also known as lamina vitrea. Bruch's membrane is thickest near optic disc (2-4 microm) and the thickness decreases towards periphery. Bruch's membrane is composed of 5 layers and from internal to external, these are

    1. Basement membrane of the RPE,
    2. Inner collagenous zone,
    3. Elastic tissue layer,
    4. Outer collagenous zone, and
    5. Basement membrane of the choriocapillaris

Outer blood–retinal barrier
The outer blood–retina barrier (BRB) is composed of three structural entities, the fenestrated endothelium of the choriocapillaris, Bruch's membrane, and the retinal pigment epithelium (RPE).

Various microscopic layers of the uveal tract and their continuation can be summarised in the following table.

Iris

Ciliary body

Choroid/ Retina

 

Supra ciliary lamina

 

 

Stroma

 

BM of the anterior iris epithelium 

BM attaches the pigment epithelium to the stroma

BM of Bruch's membrane of the choroid

Anterior epithelium of iris

Pigment epithelium

Retinal pigment epithelium

Posterior pigment epithelium of iris

Non pigment epithelium

Sensory retina

 

Internal limiting membrane

Internal limiting membrane

 

Blood supply of uveal tract:

The blood supply of the uveal tract is mainly from three arteries namely short posterior ciliary arteries, long posterior ciliary arteries and anterior ciliary arteries.
The posterior ciliary arteries are branches of the ophthalmic artery, and much variation can occur in their distribution. (Two sided table)

SHORT POSTERIOR CILIARY ARTERIES : 15 to 20 short posterior ciliary arteries arise → form 10 to 20 branches → enter the sclera ibloodsupply of choroidn a ring around the optic nerve → anastomose with other branches from the short posterior ciliary arteries to form the circle of Zinn (Zinn-Haller) which encircles the optic nerve at the level of the choroid → they run in suprachoroidal space between sclera and choroid, branch and supply the choroid.

LONG POSTERIOR CILIARY ARTERIES: Two long posterior ciliary arteries enter the sclera: one lateral and one medial to the ring of short ciliary arteries → run between the sclera and the choroid to the anterior globe → enter the ciliary body and branch superiorly and inferiorly → anastomose with each other and with the anterior ciliary arteries to form a circular blood vessel, the major arterial circle of the iris. blood supply of choroid

ANTERIOR CILIARY ARTERIES : 7 anterior ciliary arteries are derived from muscular branches of ophthalmic artery ( two each from arteries of superior rectus, medial rectus, inferior rectus and only one from lateral rectus muscle)→ reache episclera, form plexus and  give branches →pierce sclera near the limbus to enter the eye→anastomoses with long posterior ciliary arteies to form major arterial circle of iris

Branches from major arterial circle enter iris and anastomoses with each other to form minor arterial circle.

 

 

Dr. Parthopratim Dutta MajumderIllustrated Ocular Anatomy is a web based free-access portal for anatomy of eye.  Perhaps it is the first of its kind as both the images and texts are authored by an ophthalmologist. Dr. Parthopratim Dutta Majumder completed his graduation and post-graduation from Silchar Medical College & Hospital, Assam University. He completed his fellowship in medical retina and uvea from Sankara Nethralaya and is now working in the department of uvea and intraocular inflammation as Consultant. He has written many chapters in many books. He was awarded with Dr. TLK Row Endowment Award for the best associate consultant 2010-11. He is life-memebr of the All India, Delhi, All Assam Ophthalmological Societies and uveitis society of India. He has received Nataraj Pillai award for best scientific paper in 2009. He has attended and presented paper in various national and international conferences. His areas of interest include medical management of uveitis and scleritis, phacoemulsification in uveitic cataracts and offcourse graphic design. For water mark free images please write to me at drparthopratim@gmail.com