sclrea, episclera uvea

Question 1

Yellowing of the sclera is MOST commonly caused by excessive plasma levels of which of the following substances?

Albumin

Creatinine

Alkaline phosphatase

Blood urea nitrogen

Correct answer Bilirubin

Answer 1

Bilirubin
Yellowish pigmentation of the conjunctiva, skin, and other mucous membranes is known as jaundice. Jaundice is caused by increased levels of bilirubin in the blood (hyperbilirubinemia), which subsequently leads to an elevated concentration of bilirubin in the extracellular fluid. Normal blood plasma levels of bilirubin should be below 1.2 mg/dL. Concentrations above about 3mg/dL typically lead to jaundice. Jaundice is most often seen in liver disease (such as hepatitis) or liver cancer. Therefore, if a patient presents with yellowish discoloration of the sclera, liver function tests should be ordered immediately.

Question 2

Slit-lamp examination of your 13 year-old patient with a history of Down syndrome reveals the presence of whitish, pale lesions at the peripheral iris stroma in both eyes. What is the name of this finding?
Brushfield spots

Koeppe nodules

Mammilations

Lisch nodules

Busacca nodules

Answer 2

Brushfield spots
Brushfield spots are small whitish or greyish lesions that are typically found circumferentially around the peripheral region of the iris. They represent focal areas of stromal hyperplasia that are surrounded by areas of relative hypoplasia. Brushfield spots are more commonly observed in patients with lightly pigmented irides. This finding can be observed in some normal individuals but has a strong association in patients with Down syndrome.

Lisch nodules are small hyper-pigmented lesions that are observed in almost all cases of neurofibromatosis-1. Mammilations are also associated with neurofibromatosis (as well as congenital ocular melanocytosis, Axenfeld-Rieger anomaly, and Peters anomaly) and present as tiny conical or vitelliform lesions that either partially or completely cover the anterior surface of the iris.

Koeppe and Busacca nodules are iris lesions that are associated with granulomatous uveitis; however, their placement differs from one another. Koeppe nodules are observed at the iris pupillary border, in contrast to Busacca nodules, which are found in the mid-iris stroma.

Question 3

The arterial supply of the anterior segment of the eye originates from which 2 of the following sources? (Select 2)

Short posterior ciliary arteries

Central retinal artery

Long posterior ciliary arteries

Supraorbital artery

Anterior ciliary arteries

Answer 3

Long posterior ciliary arteriesAnterior ciliary arteries
The arterial blood supply to the anterior segment of the eye comes from the anterior ciliary arteries (ACAs), as well as the terminal branches of the long posterior ciliary arteries (LPCAs).

The LPCAs arise from branches of the ophthalmic artery. They pierce the posterior aspect of the sclera and run anteriorly along either side of the eye, between the sclera and the choroid. The ACAs are derived from branches of the ophthalmic artery and run anteriorly with the extraocular muscles. They pierce the sclera near the area of the cornea. The LPCAs and ACAs together form two sagittal arterial circles and two coronal arterial circles, called the episcleral arterial circle superficially and the greater circle of the iris deeply. The physiology of the arterial flow in this region ensures that the anterior segment of the eye is always supplied with an adequate supply of blood.

Question 4

Which 2 of the following ocular conditions are MOST likely to lead to the development of a Vossius ring? (Select 2)

Prior pupillary block glaucoma

Prior anterior synechiae

Prior posterior synechiae

Blunt ocular trauma

Herpes simplex

Answer 4

Prior posterior synechiae
Blunt ocular trauma

• A Vossius ring refers to an annular ring of iris pigment that can be seen on the anterior capsule of the crystalline lens. A Vossius ring may be observed following blunt ocular trauma, in which the pupillary edge of the iris is forced against the anterior lens capsule; a concurrent traumatic cataract is also typically found in these cases. A Vossius ring may also occur secondary to posterior synechiae that have formed between the pupillary border and crystalline lens and then broken by mydriasis.

Question 5

According to the Standardization of Uveitis Nomenclature (SUN) guidelines, a marked amount of anterior chamber flare in which iris and lens details are hazy is consistent with which of the following grades?

Grade 0.5+

Grade 1+

Grade 3+

Grade 4+

Grade 2+

Answer 5

Grade 3+
The Standardization of Uveitis Nomenclature (SUN) group defined clinical measurements of inflammation for the purpose of standardizing reporting and recording of clinical data. The classification for the presence of anterior chamber flare is as follows:

Grade / Description

0 / None
1+ / Faint
2+ / Moderate (iris and lens detail clear)
3+ / Marked (iris and lens details hazy)
4+ / Intense (fibrin or plastic aqueous)

Question 6

What is the correct order of the scleral lamina from the most anterior to most posterior?

Stroma–> episclera–> lamina fusca

Lamina fusca–> stroma–> episclera

Episclera–> lamina fusca–>stroma

Episclera–>stroma–> lamina fusca

Stroma–> lamina fusca–> episclera

Answer 6

Episclera–>stroma–> lamina fusca
The first layer of the sclera is the episclera, a thin and highly vascular layer. The second layer is the stroma and is sometimes also referred to as the sclera proper. The stromal layer makes up the majority of the sclera. Lastly, the lamina fusca is the most internal layer. This layer is the thinnest and most pigmented due to the population of melanocytes that reside here. The lamina fusca and the choroid are separated from each other by a potential space termed the perichoroidal space. This space is important as it houses nerves and arteries.

Question 7

Which of the following BEST describes the etiology of the presence of anterior chamber flare in a patient with iritis?

Protein in the anterior chamber due to breakdown of the blood-retinal barrier

Cells in the anterior chamber due to breakdown of the blood-aqueous barrier

Cells in the anterior chamber due to breakdown of the blood-retinal barrier

Protein in the anterior chamber due to breakdown of the blood-aqueous barrier

Answer 7

Protein in the anterior chamber due to breakdown of the blood-aqueous barrier

Flare in the anterior chamber refers to presence of an increased amount of protein in the aqueous fluid, and is often seen in association with cells. Aqueous cells and flare occur secondary to the breakdown of the blood-aqueous barrier as a result of trauma, infection, inflammation due to uveitis, scleritis, keratitis, or ocular surgery.

Cells and flare in the anterior chamber may be difficult to appreciate in mild cases and are best observed when viewed what a short, narrow slit-lamp beam, directed at an oblique angle through the pupil. All room lights should be completely turned off and the observer allowed time to dark-adapt. Cells will appear as small white particles floating in the anterior chamber, while flare makes the aqueous fluid appear hazy or cloudy (like smoke in a dark room).

Question 8

Which muscle group of the ciliary muscle originates at the ciliary tendon and inserts into the suprachoroid forming muscle stars?

Skeletal muscle

Circular muscle

Longitudinal muscle

Radial muscle

Answer 8

Longitudinal muscle
All of the three muscle groups, the longitudinal, radial and circular originate from the ciliary tendon but only the longitudinal muscle terminates at the suprachoroid. The radial muscles terminate onto the ciliary processes. Lastly, the circular muscles also insert onto the ciliary processes but they terminate onto the anterior ends of the processes. Skeletal muscle is not found in the ciliary muscle.

Question 9

Which of the following structures is responsible for the formation of aqueous through the process of active secretion?

Juxtacanalicular trabecular meshwork

Ciliary body stroma

Ciliary body zonules

Pigmented ciliary epithelium
Non-pigmented ciliary epithelium

Answer 9

Non-pigmented ciliary epithelium
Aqueous formation by the process of active secretion occurs as a result of secretion of ions by the non-pigmented layer of the ciliary epithelium. This leads to an accumulation of ions in the posterior chamber due to the presence of tight junctions that exist between the non-pigmented ciliary epithelial cells. A strong osmotic pressure difference is then created across the ciliary epithelial cells, which subsequently causes water to passively move into the posterior chamber. Active secretion accounts for the vast majority of aqueous humor production (80-90%) in comparison to passive secretion (ultrafiltration and diffusion).

Question 10

The non-pigmented epithelium of the ciliary body is continuous anteriorly with what layer of the iris?

The anterior epithelium

Correct answer The posterior pigmented epithelium

The stroma

Anterior limiting layer

Answer 10

he non-pigmented epithelium of the ciliary body is continuous anteriorly with the posterior pigmented epithelium of the iris and continuous posteriorly with the neurosensory retina. The non-pigmented epithelium is the most internal layer of the ciliary body and comes into contact with the aqueous humor. An important fact to remember is that the apexes of the non-pigmented epithelium of the ciliary body face towards the exterior of the eye, while the cells of the pigmented epithelium apexes face internally; therefore, the cells of these two layers face apex to apex.

Question 11

Which area of the trabecular meshwork offers the greatest resistance to outflow?

Canal of Schlemm

Uveal meshwork

Corneoscleral meshwork

Juxtacanalicular tissue

Answer 11

Juxtacanalicular tissue
The uveal meshwork possesses the largest pore size and it is the first area of the trabecular meshwork through which the aqueous drains. The corneoscleral meshwork is the thickest portion of the trabecular meshwork and has pore sizes that are slightly smaller than those of the uveal meshwork. The juxtacanalicular layer is quite thin, around 10-20 microns, and does not contain pores but rather a layer of endothelial cells that form vacuoles that allow for drainage of aqueous into the canals of Schlemm. The canals of Schlemm are not considered a part of the trabecular meshwork.

Question 12

Which structure of the ciliary body is responsible for production of the aqueous humor?

Bruch’s membrane

Unstriated muscle

Pars plicata

Pars plana

Answer 12

Pars plicata

The ciliary body extends anteriorly from the iris to the ora serrata. The ciliary body is split into two divisions, the pars plicata and the pars plana. The pars plicata consists of the anterior one-third of the ciliary body and is composed of ciliary processes that secrete aqueous humor. The ciliary processes are thin ridges that serve to increase the surface area of the ciliary body. The pars plana makes up the bulk of the ciliary body consisting of the posterior two-thirds.

Question 13

A patient presents to your office reporting recent blunt trauma to the eye. Biomicroscopy reveals a hyphema of the right eye. Which of the following procedures should be avoided in this patient?

Use of sodium fluorescein to evaluate the integrity of the corneal surface

Visual fields testing

Non-contact tonometry

Gonioscopy

Measurement of visual acuity

Answer 13

Gonioscopy
A hyphema is defined as blood in the anterior chamber, which typically pools inferiorly. When a patient presents with an acute hyphema, gonioscopy is contraindicated as it may increase the likelihood of re-bleeding and should be performed 2-4 weeks after the initial trauma, allowing time for the blood to clear from the anterior chamber. Evaluation of a hyphema should include observation of the anterior chamber to assess for potential damage to the cornea or iris. Intraocular pressure will likely be elevated. It is also important to ensure that the globe is not compromised and that orbital fractures are absent. Gonioscopy should be performed several weeks later to evaluate the angle for possible recession.

Question 14

Which of the following correctly describes the autonomic innervation of the iris muscles?

The iris sphincter and iris dilator are both innervated parasympathetically

The iris sphincter is innervated sympathetically and the iris dilator is innervated parasympathetically

The iris sphincter and iris dilator are both innervated sympathetically

The iris sphincter is innervated parasympathetically and the iris dilator is innervated sympathetically

Answer 14

The iris sphincter is innervated parasympathetically and the iris dilator is innervated sympathetically
Stimulation of the sympathetic nervous system results in pupil dilation and the parasympathetic nervous system pupil constriction. Accordingly, the sphincter muscle (which constricts the pupil) is innervated by the parasympathetic nervous system and the dilator muscle (which dilates the pupil) is innervated by the sympathetic nervous system.

Question 15

What is the MOST common cause of episcleritis?

Lyme disease

Systemic lupus erythematosus

Gout

Idiopathic

Rheumatoid arthritis

Answer 15

Idiopathic
Episcleritis is a condition in which the episclera becomes inflamed either unilaterally or bilaterally. The inflammation is limited to one sector of the eye, leaving the cornea and other ocular structures unaffected. Vision is not impaired by episcleritis, but occasionally there may be a mobile nodule, and the affected area may be tender to the touch. Episcleritis has a higher affinity in females and may be seen in conjunction with gout, Herpes zoster, Crohn’s disease, syphilis, Lyme disease, systemic lupus erythematosus and rheumatoid arthritis (among others), but the most common cause is generally unknown. The condition is self-limiting, and treatment includes the use of non-preserved artificial tears (due to increased frequency of use) and topical steroids or non-steroidal anti-inflammatory drops for moderate to severe forms of episcleritis.

Question 16

The trabecular meshwork can be divided into three components. What is the correct order of these components from most internal to most external?

The corneoscleral meshwork, juxtacanalicular tissue, and the uveal meshwork

The corneoscleral meshwork, uveal meshwork, and the juxtacanalicular tissue

The uveal meshwork, juxtacanalicular tissue, and the corneoscleral meshwork

The uveal meshwork, corneoscleral meshwork, and the juxtacanalicular tissue

The juxtacanalicular tissue, corneoscleral meshwork, and the uveal meshwork

Answer 16

The uveal meshwork, corneoscleral meshwork, and the juxtacanalicular tissue
The trabecular meshwork is important for aqueous drainage. The correct exit route of aqueous from most internal to the most external structure is the uveal meshwork, the corneoscleral meshwork followed by the juxtacanalicular tissue. A blockage at any of these locations will cause in increase in intraocular pressure which can lead to glaucoma.

Question 17

A 41-year-old male patient with a history of Behcet’s syndrome presents at your office with an extremely red, painful, and photophobic eye. Upon slit-lamp examination you observe severe intraocular inflammation in which cells have begun to settle in the inferior part of the anterior chamber. What it the name of this finding?

Hypopyon

Hypotony

Hyphema

Snow-banking

Answer 17

Hypopyon

In cases of uveitis in which there is an extensive amount of intraocular inflammation, cells tend to settle in the inferior portion of the anterior chamber, which can be observed on slit-lamp examination. This ocular finding is known as hypopyon.

Hypotony is an ocular condition characterized by severely decreased intraocular pressure (IOP), typically 5-6mmHg or less. When IOP reaches these levels, there are usually associated anatomical and/or functional abnormalities of the eye that coexist, such as corneal striae, aqueous flare, choroidal effusions, and macular folds.

Hyphema is an ocular finding in which blood is present in the anterior chamber. As in cases of hypopyon, red blood cells may also pool in the inferior region of the anterior chamber.

Snow-banking is a term that is used in patients with intermediate uveitis in which aggregates of inflammatory cells can be observed lying over the inferior pars plana.

Question 18

During slit lamp evaluation of your 65 year-old patient with a long-standing history of diabetes, you carefully examine the anterior segment for evidence of rubeosis iridis. At which location on the iris are you MOST likely to observe abnormal blood vessel growth first?

Along the surface of the iris in the mid-periphery

In the mid-periphery lying deep within the iris stroma

In the iris periphery near the anterior chamber angle

Along the anterior surface of the iris at the pupillary margin

Answer 18

Along the anterior surface of the iris at the pupillary margin
Rubeosis iridis (iris neovascularization) occurs as a result of severe retinal ischemia, typically secondary to diabetes mellitus, ischemic central retinal vein occlusion, and carotid obstructive disease. It is thought that hypoxic retinal tissue produces certain growth factors (such as vascular endothelial growth factor, VEGF), in an attempt to re-vascularize these areas. In addition to causing neovascularization of the retinal tissue, these factors can diffuse into the anterior chamber, resulting in abnormal blood vessel growth within the iris and anterior chamber angle. 

In most cases, neovascularization is initially visible as tiny dilated capillary tufts coursing the surface of the iris at the pupillary margin. These vessels may be difficult to observe; therefore, careful examination of this region under high magnification is important in all patients with a risk for development of rubeosis iridis. As neovascularization progresses, these blood vessels will grow radially over the surface of the iris tissue towards the angle, which can impede aqueous outflow initially and eventually lead to secondary angle closure by contraction of the fibrovascular membrane.

It is important to note that neovascularization of the angle in the absence of visible neovascularization at the pupillary margin can occur, but this is rare and typically only occurs in cases of an ischemic central retinal vein occlusion. Also, patients with lightly colored irides may have visible blood vessels within the iris stroma; this is a normal finding.

Question 19

Where is the thickest portion of the iris?

The central pupillary zone

The pupillary ruff

The peripheral ciliary zone

The collarette

Answer 19

The collarette
- The anterior surface of the iris is divided into two main zones; the central pupillary and the peripheral ciliary zones. The central pupillary zone is located just next to the pupillary ruff. The collarette lays adjacent to the central pupillary zone and serves as a junction between the central pupillary zone and the peripheral ciliary zone. The collarette typically has a distinctive zigzag appearance to its edges. The collarette is roughly 0.6 mm thick. The iris ruff surrounds the pupil edge and appears as a dark, scalloped border. The pupillary ruff is the visible portion of the posterior pigmented epithelium.

Question 20

Iris colobomas form due to incomplete closure of the choroidal fissure. This usually results in a keyhole-shaped defect in which region of the iris?

Superonasal

Inferonasal

Superotemporal

Inferotemporal

Answer 20

Inferonasal
An iris coloboma is an inferonasal, keyhole-shaped defect. The remainder of the iris is normal. Atypical colobomas may develop at sites other than the inferonasal area.

Question 21

Which of the following regions of the sclera is the weakest and most likely to cup outward when there is increased intraocular pressure (i.e. glaucoma)?

Limbus

Palisades of Vogt

Correct answer Lamina cribrosa

Scleral spur

Answer 21

Lamina cribrosa
The lamina cribrosa is the posterior scleral foramen through which the optic nerve passes. It is a sieve-like structure with interwoven collagen fibrils forming canals allowing optic nerve fibers to pass. It is the weakest area of the outer connective tissue tunic which is why cupping out or ectasia may be seen as a sign of increased intraocular pressure. The scleral spur is a region of circularly oriented collagen bundles which serves as the origin of the longitudinal ciliary muscle fibers. The limbus is the band located at the junction of the cornea and sclera. Here, there is a transition from squamous corneal epithelium to columnar conjunctival epithelium, as well as a transition from the very regular corneal stroma to the irregular scleral stroma, and the termination of Bowman’s layer, Descemet’s membrane and the corneal endothelium. The palisades of Vogt are radial projections of the limbal epithelium that extend into the cornea; it is an area where corneal epithelial stem cells reside.

Question 22

The bulk of aqueous humor is formed by which mechanism?

Osmosis

Active transport

Diffusion

Ultrafiltration

Answer 22

Active transport

The ciliary processes of the pars plicata produce the aqueous humor. It is created by three different methods which are as described below.

Active transport produces the majority of aqueous humor. It requires the use of sodium, chloride and bicarbonate ions that serve to create an osmotic gradient between the interdigitations of the non-pigmented epithelial cells of the ciliary body. This creates a higher concentration of solutes inside the cells near their tight junctions which diminishes towards the posterior chamber, pulling water into the posterior chamber.

Ultrafiltration accounts for a small amount of aqueous produced. Fluid is pushed out of the ciliary processes via capillary hydrostatic forces (blood pressure).

Diffusion is responsible for producing a very small amount of aqueous. Particles in fluid flow down their concentration gradient moving from an area of high concentration to an area of low particle concentration.

Question 23

Which of the following types of nodules associated with granulomatous uveitis are found in the mid-iris stroma?

Dalen-Fuchs nodules

Berlin nodules

Busacca nodules

Koeppe nodules

Answer 23

Busacca nodules
Iris nodules typically occur in cases of chronic granulomatous anterior uveitis. Busacca, Koeppe, and Berlin nodules are all found on the iris but in different locations. Busacca nodules are found in the mid-iris stroma, while Koeppe nodules are seen at the pupillary border; Berlin nodules are present in the anterior chamber angle (best viewed with gonioscopy). Dalen-Fuchs nodules are chorioretinal lesions that represent epithelioid cells found between Bruch’s membrane and the retinal pigment epithelium. Formation of these nodules is typically associated with sympathetic ophthalmia and Vogt-Koyanagi-Harada disease.

Question 24

Upon dissection, the trabecular meshwork appears like a triangle whose apex points towards which structure?

The cornea

The scleral spur

The lens

The ciliary body

Answer 24

The cornea
The trabecular meshwork is triangular in shape with the base of the triangle abutting the scleral spur. The apex of the trabecular meshwork points towards the cornea, and its anterior surface points towards the ciliary body. This is in opposition to the ciliary body whose apex points posteriorly towards the ora serrata.

Question 25

In most cases of acute anterior uveitis, the intraocular pressure is decreased due to reduced secretion of aqueous by the ciliary epithelium. Which 2 of the following causes of acute anterior uveitis typically result in ELEVATED intraocular pressure? (Select 2)

Correct answer Herpes

Behcet’s syndrome

Bacterial infection

Correct answer Posner-Schlossman syndrome

Idiopathic

Answer 25

Herpes
Posner-Schlossman syndrome=Glaucomatocyclitic Crisis

Patients presenting with acute anterior uveitis typically demonstrate a decrease in their intraocular pressure (IOP). This is due to the fact that an inflamed ciliary body often produces less aqueous as compared to its basal level of secretion. However, there are some etiologies of anterior uveitis that more commonly result in elevated intraocular pressures. In both herpetic uveitis and Posner-Schlossman syndrome, an increase in IOP can be attributed to subsequent trabeculitis, resulting in decreased outflow of aqueous. Therefore, IOP can be an important component to diagnosing the cause of a case of acute anterior uveitis.

Question 26

Biomicroscopic examination reveals neovascular changes on the iris surface, which is a finding known as Rubeosis iridis. Which of the following 3 conditions are associated with this finding? (Select 3)

Diabetes mellitus

Systemic lupus erythematosus

Central retinal vein occlusion

Recurrent corneal erosion

Keratoconus

Temporal arteritis

Correct answer Chronic retinal detachment

Answer 26

Central retinal vein occlusion Diabetes mellitus
Chronic retinal detachment
hough a vascular disease, temporal arteritis does not cause ischemia to the iris and therefore it does not result in neovascularization. Diabetes, in association with retinopathy, is the most common cause. Rubeosis iridis also occurs as a result of central retinal venous thrombosis and has been reported with chronic retinal detachments as well. The most devastating ocular consequence is contracture of the vessels, causing acute angle closure glaucoma.

Question 27

An elderly patient is seen at your office for a follow-up visit. She was diagnosed with iritis 1 week ago and is currently being managed with Pred Forte® topical eye drops every 2 hours. She reports no change in her symptomology and is still very photophobic, and her eye still bothers her. Slit lamp evaluation reveals no change in her clinical signs. Which of the following conditions may be the underlying cause of a non-responsive iritis?

Behcet’s syndrome

Rheumatoid arthritis

Tuberculosis

An intraocular tumor

Answer 27

An intraocular tumor

Explanation - Patients, especially the elderly, may exhibit a non-responsive iritis, which is caused by an intraocular tumor, leukemia, metastatic cancer, or non-Hodgkin’s lymphoma. Therefore, if a patient is being treated for iritis and the condition is not responding to conventional topical therapeutic treatment, further evaluation is warranted.

Patients with iritis, also known as anterior uveitis, typically will report photophobia, excessive lacrimation, pain, and diminished visual acuity. This condition is caused by either inflammation of the iris or of both the iris and the anterior portion of the ciliary body (iridocyclitis). Clinical signs include: keratic precipitates (which are variable in size and distribution, depending upon the etiology of the iritis) deposited on the corneal endothelium, cells and flare (protein that has leaked from iris vessels into the anterior chamber), sluggish and slightly constricted pupils caused by swelling of the uveal tract, irregular pupil margins (if posterior synechiae are present), and in the event of granulomatous inflammation, iris nodules. An acute episode of anterior uveitis or chronic uveitis may cause the formation of posterior synechiae. Cells may also be present in the vitreal chamber; however, the number of cells in the anterior chamber should exceed the number seen in the vitreous cavity. Treatment of iritis includes a cycloplegic agent to help prevent formation or promote breakdown of synechiae. A cycloplegic also aids in pain management by controlling pupil size and avoiding unnecessary movement of the iris muscles, which can be very painful with this inflammatory condition. UV protection (tinted lenses) is also helpful in management of the associated photophobia. A topical steroid is prescribed to reduce the inflammatory response. It is very important to slowly taper the use of the steroid; otherwise there is a risk of rebound inflammation.

Although rheumatoid arthritis, Behcet’s syndrome, and tuberculosis can lead to the development of an iritis, this associated iritis can typically be managed via traditional methods such as topical steroid and cycloplegic drops.

Question 28

A 27-year old male presents with decreased vision, pain, and redness of both eyes. Slit lamp examination reveals several large “mutton-fat” keratic precipitates (KPs) on the corneal endothelial surface. Which two of the following types of cells make up these KPs? (Select 2)

Lymphocytes

Macrophages

Erythrocytes

Neutrophils

Epithelioid cells

Answer 28

Macrophages
Epithelioid cells
The presence of keratic precipitates (KPs) on the corneal endothelium is an anterior segment sign indicating the presence of uveitis. KPs are aggregates of inflammatory cells that are typically observed on the inferior half of the cornea due to the convection currents in the aqueous humour. Their composition and appearance differs with the severity, duration, and type of uveitis (non-granulomatous vs. granulomatous).

Non-granulomatous KPs are composed of neutrophils and lymphocytes and have a clinical appearance that resembles small, discrete, fleck-like, linear, or stellate corneal endothelial opacities. These types of KPs are usually dirty-white in color and there may be hundreds in number arranged irregularly on the back surface of the cornea. On the other hand, mutton-fat KPs typically occur in granulomatous types of uveitis and are composed of macrophages and epithelioid cells. The appearance differs in that these types of KPs are much larger and thicker and they have a fluffy, greasy, or waxy look. Additionally, mutton-fat KPs are usually fewer in number (10-15).

Other types of KPs include red KPs, which are formed when red blood cells are present in the anterior chamber in addition to the inflammatory cells (hemorrhagic uveitis). Old KPs may also be observed in cases of resolved uveitis. During the healing process, KPs tend to shrink, fade, and become pigmented and irregular in shape. Old mutton-fat KPs have been described of having a ground-glass appearance due to hyalinization.

Question 29

You correctly diagnose your 31 year-old female patient with acute unilateral anterior uveitis. When should laboratory testing typically be initiated in otherwise healthy patients presenting with this condition?

After the second episode

After the third episode

After the first episode

Laboratory testing is not indicated in acute cases of uveitis

After 1 year of recurrent episodes

Answer 29

After the second episode
When the patient presents with an anterior uveitis that has an initial presentation, occurs unilaterally, and the patient is otherwise healthy with no other systemic symptoms, no further laboratory testing is usually indicated. On the other hand, patients with recurrent, chronic, or bilateral presentations, or patients that have other symptoms possibly indicating the presence of an associated systemic condition, should undergo a thorough work-up to determine the underlying etiology. Typically, in conjunction with the patient’s primary care provider, laboratory testing should be initiated in a patient where anterior uveitis recurs after cessation of treatment (2nd episode). In these cases, there is a much higher risk of being associated with a systemic disease, as compared to a patient with a single episode of intraocular inflammation.

When indicated, minimal lab testing should include the following:

• Complete blood cell count (CBC)
• Urinalysis
• Lyme titers
• HLA-B27 test (spondylarthropathies)
• Antinuclear antibody (ANA) test (juvenile arthritis)
• Angiotensin converting enzyme (ACE) test (sarcoidosis)
• Venereal disease research laboratory (VDRL) test (syphilis)
• Fluorescent treponemal antibody absorption (FTA-ABS) test (syphilis)