Eye conditions: Inflammation, infections and trauma: Pathology review

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Case study0:00–1:03

While doing your rounds, you meet a 4 day old newborn girl named Caitlin who is brought to the emergency department due to redness and swelling of the eyes.
Physical examination shows bilateral eye erythema and purulent discharge. The infant was born at home to a mother who received no prenatal care and is unable to provide any medical history.
Some days later, 41-year-old Joshua comes to the ophthalmology clinic complaining of black spots and blurry vision that started about two weeks ago.
He mentions that the spots go away when he closes his left eye. On examination, visual acuity is 2100 in the right eye and 2020 in the left.
Fundus examination is pictured. His medical history includes a diagnosis of HIV infection eight years ago.
Based on initial presentation, both Caitlin and Joshua have some form of inflammatory, infectious, or traumatic eye condition.
But first, a bit of physiology real quick. If we zoom into the wall of the eye, it is made up of three major layers.

Physiology1:03–2:00

There's a fibrous outer layer that contains the cornea and sclera. The outer surface of the sclera is covered by a mucous membrane called conjunctiva, which also lines the inside of the eyelids.
The middle vascular layer is called uvea and consists of the iris, choroid, and ciliary body. Finally, the neural layer consists of the retina, which helps convert light into neural signals that travel via the optic nerve to the brain for visual processing.
OK, let's start with stye, also known as hordeolum, which is a common bacterial infection of the sebaceous glands of the eyelids.
For your exams, remember that the most common pathogen is Staphylococcus aureus. Styes present as painful, red, pus-filled lumps and are usually located at the lid margin, in which case they are known as external styes or under the conjunctival side of the eyelid, also called internal styes.

Stye2:00–2:59

For your exams, keep in mind that for unknown reasons, styes tend to be more common in individuals with acne vulgaris and diabetes mellitus.
Diagnosis is clinical, and treatment usually involves warm compresses, massage, and topical antibiotics. Now it's important to differentiate a stye from a calasian.
A calasian results from the obstruction of sebaceous glands of the eyelids without any infection. It presents as a slow growing, painless, rubbery nodule, usually in the middle of the eyelid.
Diagnosis is clinical and no treatment is necessary since it's usually self resolving. Next is conjunctivitis, which is inflammation of the conjunctiva.

Chalazion2:59–3:26

For your exams, remember that there are two main types of conjunctivitis infectious and noninfectious. Infectious conjunctivitis can be further divided into viral and bacterial conjunctivitis.
Viral conjunctivitis is the most common one and is typically caused by adenovirus, but can also be due to herpes simplex virus or varicella zoster virus.
Bacterial conjunctivitis can be gonococcal, which is caused by nasseria gonorrhea, or chlamydial, which is caused by chlamydia trachomatis.

Conjunctivitis3:26–9:56

For your test, remember that gonococcal conjunctivitis tends to be more severe and might be accompanied by various complications.
That's because gonococci can penetrate further into the cornea, causing corneal edema, ulceration, or even scarring and perforation.
In some cases, gonococci could get even deeper and involve the interior of the eye, causing endophthalmitis or make it into the systemic circulation and spread throughout the body.
Now noninfectious conjunctivitis includes allergic conjunctivitis, which is usually caused by airborne allergens like pollen, and non-allergic conjunctivitis caused by chemical or mechanical irritation of the conjunctiva.
A high yield fact is that in newborns, chemical conjunctivitis is most often caused by the use of ophthalmic silver nitrate for prophylaxis against ocular gonococcal infection.
In terms of symptoms, all types of conjunctivitis present with unilateral or bilateral pinkish or red eyes and sometimes mild eyelid and conjunctival edema, sensitivity to light, and excessive lachrymation.
For your exam, you must remember what sets the different types apart, which is their discharge. So in viral and noninfectious conjunctivitis.
The discharge is sparse, mucoid, or watery, while in bacterial conjunctivitis it's purulent white, yellow, or green. In newborns, remember that gonococcal conjunctivitis tends to produce a greater amount of purulent discharge than chlamydial conjunctivitis.
If there's corneal involvement or endophthalmitis, gonococcal conjunctivitis may also be accompanied by vision impairment or even vision loss.
For allergic conjunctivitis, a telltale sign is excessive eye itchiness or pain. For neonatal conjunctivitis, another high yield clue that helps you differentiate between gonococcal, chlamydial, and chemical conjunctivitis is the time of presentation after birth.
So chemical conjunctivitis typically presents on the first day after delivery. Gonococcal conjunctivitis between day 2 and 7.
And chlamydial conjunctivitis between days 5 and 14. Now, diagnosis is usually clinical, but for infectious conjunctivitis, laboratory tests of the conjunctival exudate might also be necessary.
Specifically for viral conjunctivitis, rapid antigen detection tests can be used, whereas in gonococcal conjunctivitis, gram stains can detect typical gram-negative intracellular kidney bean shaped diplococci.
Keep in mind that chlamydia does not graham stain well. That's mainly because its obligate intracellular and its cell wall lacks peptidoglycan, so it can't retain the dye used during gram staining.
Instead, chlamydia is best stained with Gemza stain. Which colors them pinkish blue.
Cultures of the eggudate are rarely used, but for your exams, remember that Nasseria gonorrhea grows best on a special chocolate medium called Thayer Martin agar.
For treatment, viral conjunctivitis is typically self-resolving, but ocular lubricant drops or ointments might also be helpful.
On the other hand, bacterial conjunctivitis requires antibiotics. Ceftriaxone is effective for gonococcal conjunctivitis, and doxycycline or azithromycin for chlamydia trachomatous infections.
For newborns with chlamydia trachomatis, though, oral erythromycin is typically used. If simultaneous gonococcal and chlamydia infection is suspected, combination treatment includes doxycycline or a macrolide plus ceftriaxone.
For non-infectious conjunctivitis, allergic conjunctivitis is usually treated with antihistamine drops, while non-allergic conjunctivitis is usually self-resolving, but flushing the eyes along with removing and avoiding the irritant might be helpful.
Prophylaxis of conjunctivitis should be given to all newborns and involve topical erythromycin or tetracycline. Remember that silver nitrate is typically not used anymore due to its association with chemical conjunctivitis.
Another important thing to note is that this regimen doesn't prevent chlamydial conjunctivitis. Now, in keratoconjunctivitis, inflammation involves both the cornea and the conjunctiva.
This can be broken down into infectious and non-infectious keratoconjunctivitis. Infectious keratoconjunctivitis is most commonly caused by viral infections.
In 90% of the cases, this is due to adenovirus, but a high yield fact. Examiners want you to know that it can also be due to HSV1 infection.
Among non-infectious keratoconjunctivitis, the most important one to focus on is keratoconjunctivitis sica, also known as dry eye disease.
This is a classical manifestation of Sjogren's syndrome, which is an autoimmune condition that tends to involve the lacrimal glands, resulting in decreased tear secretion and eye dryness, which can ultimately lead to inflammation and ulceration of the cornea and conjunctiva.
In addition to the symptoms of conjunctivitis like pain, redness, tearing, and sensitivity to light, the most classic sign of corneal involvement is blurry vision.
For keratoconjunctivitis sica, look for eye dryness and irritation, which are characteristically described as a sensation of sand in the eyes.
Diagnosis is confirmed with slit lamp examination. This might show a branching dendritic lesion on the cornea which looks a bit like the tree-like dendrites of a neuron, and this pattern is classic for HSV1 keratoconjunctivitis.
No treatment is typically necessary for viral keratoconjunctivitis, while keratoconjunctivitis sica may benefit from artificial tears or lubricants.

Keratoconjunctivitis9:56–12:04

Next is uveitis, which is inflammation of the uvea. There are 3 main types of uveitis anterior uveitis or iritis, which is the most common one, and affects the iris.
Intermediate uveitis or vitritis, which is the least common and affects the vitreous body. And posterior uveitis or choroiditis, which affects the choroid, which is the thin pigmented vascular coat of the eye.
Posterior uveitis can also spread to the retina, causing chorioretinitis, which is the simultaneous inflammation of the choroid and retina.
Chorioretinitis is most commonly caused by congenital infections which are transmitted from the mother to the fetus via the placenta.
For your exams, these infections can be remembered with the acronym Torch, which stands for toxoplasma, other infectious agents, usually syphilis, rubella, cytomegalovirus, and herpes simplex.
For toxoplasma, look for the classic triad of chorioretinitis, hydrocephalus, and intracranial calcifications. In contrast, in congenital CMV infections, chorioretinitis will usually be accompanied by hearing loss, seizures, and periveventricular calcifications.
In both congenital CMV and rubella infections. The baby might also present with red or purple spots on the skin, typically known as blueberry muffin rash.
Now examiners love uveitis because it's often associated with systemic inflammatory conditions such as sarcoidosis, rheumatoid arthritis, seronegative spondyloarthropathies like ankylosing spondylitis, and juvenile idiopathic arthritis, Bechette syndrome, vasculitities, and inflammatory bowel disease, especially Crohn's disease.
These inflammatory conditions are also associated with a higher expression of the gene HLA-B27, which encodes for a specific type of MHC class one molecule.

Uveitis & chorioretiniti12:04–16:04

Infectious causes, including brucellosis, tuberculosis, leptospirosis, and Lyme disease are also possible. Now symptoms may include redness of the eye, visual disturbances such as floaters and photophobia.
For your exams, it's also important to remember that anterior uveitis is accompanied by dull periocular pain, unlike posterior uveitis, which is painless.
That's because the choroid is not innervated by sensory nerves. Diagnosis starts with external inspection of the eyes which in severe cases of interior uveitis might reveal hypopion, which is the accumulation of pus in the inferior part of the anterior chamber.
Confirmation of the diagnosis comes with ophthalmoscopic examination, including slit lamp and funduscopic examination, along with conjunctival smear with microscopy, cytology, and culture if an infectious cause is suspected.
Treatment includes topical or systemic corticosteroids, as well as antibiotics or antiviral therapy, in the case of infectious uveitis.
Now retinitis or inflammation of the retina is often caused by CMV infection in immunocompromised individuals, especially those with AIDS or transplant recipients.
Symptoms include blurring of vision, dark spots in the visual field called scotomas, or even total vision loss. On fundoscopy, there is a characteristic pizza pie appearance with retinal hemorrhages and yellowish white exudates.
Treatment includes anti-CMV agents like gancyclovir and phoscarnate. Moving on to thyroid eye disease, which is an autoimmune disorder of the connective tissue of the orbit, leading to potential vision problems.
Thyroid eye disease is commonly associated with Graves' disease, which is an autoimmune disorder where B cells produce antibodies against several thyroid proteins causing hyperthyroidism.
The most high yield autoantibodies you need to remember are thyroid stimulating immunoglobulins. These autoantibodies can bind to the thyroid stimulating hormone receptor or TSHR and insulin-like growth factor 1 receptor or IGF-1R activating the T cells in the retroorbital space, causing them to secrete cytokines like TNF alpha and.
and gamma, these increase fibroblast secretion of glycosamino glycans, which ultimately increase muscle swelling, muscle inflammation, and increase the adipocyte count, leading to periorbital edema and exothalamus, which is an anterior bulging of the eyes.
Lid lag or retraction might also be observed, and these are due to the increased sympathetic stimulation of the levator palpebrae superiois and superior tarsal muscles which control eye and upper eyeball movements.
Now, a high yield fact to keep in mind is that individuals with Graves' disease often have specific HLA genes, such as HLADR3 and HLAB8, which are important clues on your exams.
Diagnosis is usually clinical, but laboratory testing and imaging techniques like CT and MRI can be used to confirm the diagnosis.
Treatment usually involves immunomodulatory agents like tprotumumab, which is a human monoclonal antibody that blocks IGF-1 receptor, anti-thyroid agents, and even surgery in severe cases.
Then there's orbital cellulitis, which is an infection of the connective tissue of the orbit, mostly of the fat and ocular muscles, and it's usually caused by streptococcus pneumonia and Haemophilus influenza.

CMV retinitis16:04–16:46

For your exams, bear in mind that it's often secondary to sinusitis, particularly ethmoiditis, in young children. Symptoms include pain with eye movements, proctosis or bulging of the eyeball, redness and swelling of the eyelid, and in some cases, ophthalmoplegia or impairment of eye movement.
These are often accompanied by fever and chills. It's important to set this apart from preseptal or periorbital cellulitis, which affects the anterior portion of the eyelid without actually involving the eye, and it tends to be milder.

Graves ophthalmopathy16:46–18:43

What's high yield is that orbital cellulitis is worrisome because it can extend to deeper structures like the meninges causing meningitis or even the brain, leading to a cerebral abscess.
For diagnosis, retinal examination is typically normal, but CT imaging of the orbit can be done to assess the extent of the inflammation.
Blood cultures should also be performed to identify the causative bacteria. Treatment involves antibiotics like nafcilin, ceftriaxone, and metronidazole.
Finally, there are orbital fractures which occur when one of the bones surrounding the eyeball gets broken. There are several types of orbital fractures, including orbital rim fractures, which involve the bony outer edges of the eye socket, orbital roof fractures, and orbital floor fractures, which are also known as blowout fractures if the orbital floor collapses.
Now, in a test question, look for the history of blunt trauma to the eye. Symptoms may include unilateral periorbital pain, edema, and ecchymosis, an ophthalmos, meaning a posterior displacement of the eyeball or proptosis, meaning an anterior displacement of the eyeball.
If eye movement gets restricted, these might also be accompanied by diplopia and pain during eye movements. In severe fractures, the infraorbital and supraorbital nerves can also get involved, causing the individuals to experience numbness below the eye or in the forehead, respectively.
For diagnosis, external inspection of the eye might reveal subconjunctival hemorrhage, meaning blood on the conjunctiva or hyphema, meaning blood inside the anterior chamber.
Imaging tests like an X-ray or CT scan are also required to show the extent of the injury. Treatment depends on the severity of the fracture and can be conservative or surgical.

Orbital cellulitis18:43–20:20

All right, as a quick recap, a sty is a common bacterial infection of the eyelids, presenting as a painful red pus-filled nodule at the lid margin or in the conjunctival side of the eyelid, while a calasian is non-infectious and presents as a painless rubbery nodule in the middle of the eyelid.
Conjunctivitis is divided into infectious, which is caused by a viral or bacterial infection, and non-infectious, which includes allergic conjunctivitis and non-allergic, caused by chemical or mechanical irritation.
Uveitis can be anterior, intermediate, or posterior and is often associated with HLA-B27 positive systemic inflammatory conditions or infections.
A form of posterior uveitis is chorioretinitis, which is most commonly caused by congenital torch infections. CMV retinitis presents as scotomas and blurry vision in immunocompromised individuals and has a pizza pie appearance on fundoscopy.
Graves' ophthalmopathy classically presents with periorbital edema, exophthalmus, and lid lag, or retraction. Orbital cellulitis is commonly secondary to sinusitis and can cause proctosis and ophthalmoplegia and in severe cases progresses on to meningitis or cerebral abscess.

Orbital fractures20:20–22:01

Orbital fractures can involve the orbital rim, roof, or floor, in which case they are also known as blowout fractures. OK, back to our cases.
4 day old Caitlin presented with bilateral erythema and purulent discharge, which suggest bacterial conjunctivitis. And since the presentation was between days 2 and 7 after birth, diagnosis of gonococcal conjunctivitis is highly likely.
This was confirmed with a culture of the discharge which showed gram-negative diplococci and was followed by the administration of ceftriaxone.
On the other hand, 41-year-old Joshua came in with scotomas and a decrease in visual acuity. These findings, along with the characteristic pizza pie appearance on fundoscopy and his history of HIV infection.
Make Joshua a textbook case of CMV retinitis, which is why he was started on gancyclovir.

Review22:01–23:54

Summary23:54–21:23