Wills Eye

Scelera

Sclera tough fibrous layer that protects the surface

• Structural supporting wall that maintains eye shape and protects delicate internal structures of the eye.

Choroid

Choroid

• Vascular layer that contains blood vessels that nourish the inner parts of the eye

Cornea

• the light enters through the outer part of your eye (which is ??)

• it is clear and helps to focus the light

Pupil

• light rays pass through _

• the colored part is the iris: controls how wide the __ is

• bright light- constricts

• low light- dilates

Lens

• behind the iris

• held by ciliary muscles and suspensory ligaments

• these ciliary muscles and suspensory ligaments adjust the focal length so that we can see near and face objects (accomodation)

  • lens flattens so we can see things far away

  • it bends so that we can see things up close

Aqueous humor

• it is a viscous liquid filled in the area between the cornea and the eye lens

• prevents the eye from collapsing due to changes in atmospheric pressure

Retina

• cornea, pupil, and lens work together to focus light onto the back of the eye where the __is

• 130,000,000 cells in the__ retina that detect light and turn it into electrical signals that make their way to the optic nerve

• Rods(respond to the intensity of light) and cones (respond to the color of objects)

  • MACULA- tiny area in the retina which is responsible for clear and sharp vision

    • contains a small depression which is the fovea centralis where the maxiumum number of cones are present

Vitreous humor

• jelly like substance in the space between the lens and the retina

• helps in maintaining shape

blind spot

• a small region in the retina where the optic nerve enters the eye

• insensitive to light

Superficial Punctate Keratopathy

• (SPK) is a common eye disorder characterized by the death or damage of small groups of cells on the corneal surface, causing tiny, scattered, spot-like lesions. 

Causes: 

• Dry Eye Syndrome: A frequent cause.

• Viral Infections: Such as adenovirus or herpes simplex.

• Contact Lens Wear: Improper cleaning or overwear.

• Environmental Irritants: Exposure to wind, smoke, or UV radiation (e.g., snow blindness).

• Medication Toxicity

Symptoms: 

• Redness and irritation.

• Foreign body sensation (feeling like something is in the eye).

• Photophobia (light sensitivity).

• Watering (lacrimation).

• Mildly decreased vision. 

Doctors diagnose SPK using a slit-lamp examination, often utilizing a fluorescent eye stain dye to highlight the damaged corneal cells

Dry Eye Syndrome

The medical term for this condition is keratoconjunctivitis sicca (ker-uh-toe-kun-junk-tih-VY-tis SIK-uh). 

Dry eye syndrome (DES) is a common, chronic condition where the eyes do not produce enough tears or the tears evaporate too quickly

• Disrupts healthy tear film 

Causes: 

• Meibomian Gland Dysfunction (MGD): The most common cause, where blocked oil glands in the eyelids cause tears to evaporate too quickly.

• Aging: Natural tear production decreases with age.

• Screen Time: Prolonged computer or phone use reduces blink frequency.

Decreased tear production

Dry eyes can occur when you're unable to produce enough liquid tears, also called aqueous fluid. 

Increased tear evaporation

The oil film produced by small glands on the edge of your eyelids (meibomian glands) might become clogged. Blocked meibomian glands are more common in people with rosacea or other skin disorders.

Parts of the Tear Film

• The tear film covers the sclera and the conjunctiva (conjunctiva is a thin, transparent mucous membrane that covers the inner eyelids and the white surface of the eye. Its primary functions are to protect the eye from microbes and debris, secrete mucus and tears for lubrication, and support immune defense.)

• Outer Lipid Layer : Secreted by the meibomian glands, this oily layer reduces evaporation and stabilizes the tear film, consisting of approximately 40–45% wax esters, 40–45% cholesteryl esters, and polar lipids (OAHFAs/DiEs).

• Middle Aqueous Layer : Produced by the lacrimal glands, this layer provides oxygen, nutrients, and antimicrobial agents (lysozyme, lipocalin) to the cornea.

• Inner Mucin Layer Composed of mucins produced by goblet cells in the conjunctival epithelium, this layer coats the corneal epithelium, providing a gel-like surface that allows the aqueous layer to adhere, enhancing wettability.

The inner mucin layer is closely related to the outermost layer of the conjunctiva that contains goblet cells

Recurrent Corneal Erosion (RCE

a painful condition in which the epithelium of cornea repeatedly fails to stay securely attached to the underlying tissue bowmans membrane

• Oftentimes the eyelid can stick to the loose corneal surface hence episodes will occur at night or first thing in the morning 

• Many times there is a history of abrasion involved 

• Sensation that there is a foreign body in the eye, tearing, photophobia, recurrent attatcks of acute ocular pain 

• Slit- lamp examination with fluoroscein to determine areas of rapid tear break up 

• The epithelium. This is the cornea’s outermost layer. It’s densely packed with nerve endings and is hundreds of times more sensitive than the surface of your skin.

• Bowman’s membrane. This layer is mostly collagen, a protein similar to those that allow gelatin (like in desserts) to hold its shape once it sets. It’s there to firmly link the layers above and below.

When you have RCE, the epithelium and Bowman’s membrane don’t stick together as they should. That can cause the epithelium to erode, exposing vulnerable layers underneath. And corneal erosions are very painful because the epithelium is packed with nerve endings.

Treatment Options 

• Patching or bandage contact lenses. Both of these options provide an extra protective layer for your eye while it heals. A bandage contact lens is exactly like it sounds: a bandage that attaches to your eye like a contact lens. It helps your eye repair itself by providing a support structure.

• Cycloplegia. (in the form of eye drops) Muscles connected to your eye can make tiny adjustments to your eye shape. That helps you focus on things at varying distances. Cycloplegia involves temporarily paralyzing those muscles in the affected eye. That keeps the eye’s shape constant, making healing easier

• Eye lubrication (helps symptoms when you wake up), hypertonic saline (boosts the absorption of fluid through the surface of your eye. That improves the bonding of the epithelium to underlying layers) , and antibiotics for infection related RCE

Surgical Procedures: 

• Debridement. This involves removing damaged sections of epithelium with special tools.

• Diamond burr polishing (tool used for debridement) . The surface layer of the cornea is removed with a surgical sponge and blade.  A provider uses a special tool to buff the bowmans membrane and remove epithelium tissue from the affected corneal area. That allows it to regrow uniformly across that area of your cornea.

Stromal punctures. A provider uses a very small needle or a laser to make tiny holes into the stroma, the layer of your eye underneath Bowman’s membrane. Placing these holes precisely causes your eye to repair itself at specific points. That strengthens the bonding of the layers above.

• Amniotic membrane placement. This works like a bandage contact lens, but uses tissue taken from a placenta. The placenta is from a cesarean section delivery and goes through intensive processing to make sure it’s sterile. A provider places it directly on your eye over the affected area. The placental tissue protects the eye and promotes the regrowth of your cornea’s outer layers.

1. Fuch’s Dystrophy

• edema in the eye due to dying or damaged endothelial cells, which prevent balance fluid and prevent swelling. 

1. Genetic basis is complex

   1. More common in women than men 

   2. onset : cases start in 30s/40s but most people develop symptoms in their 50’s/60’s 

Guttae- small dark bumps (“beaten metal” appearance) in the descement layer between the stroma and the endothelial layer 

Symptoms: 

• Cloudy vision 

• Changes in vision throughout the day 

• Halos around lights

• Glares 

• Pain or grittiness from the tiny blisters on cornea

• * Autoimmune Disorders: Inflammatory conditions like rheumatoid arthritis or lupus can cause the immune system to attack and weaken corneal tissue.
  

Fluorescein staining

Bright green dye highlights epithelial defects.

Seen in:

• abrasions

• ulcers

• dry eye

• herpes simplex keratitis

Epithelial defect

area where epithelium is missing

Infiltrate

Corneal infiltrates are white or gray spots in the normally clear cornea, caused by an accumulation of white blood cells responding to inflammation or infection. They require a prompt eye exam, as distinguishing between a sterile (non-infectious) and an infectious (ulcer) cause dictates whether the treatment relies on steroids or antibiotics

White inflammatory opacity in cornea.

Can be:

• infectious

• sterile/inflammatory

Bacterial keratitis

Often:

• contact lens related

Look for:

• infiltrate

• epithelial defect

• hypopyon

Herpes simplex keratitis

VERY high-yield.

Classic finding:

• dendritic lesion with fluorescein staining

• Question: how to differentiate with Pseudodendrites: Not all branching lesions are herpes. Healing epithelial defects, contact lens toxicity, and neurotrophic keratopathy can create "pseudodendrites" that mimic the appearance but require different treatments

Fungal keratitis

Can have:

• feathery borders

• satellite lesions

In infectious keratitis we want to look for infiltrates

corneal edema

• swollen cornea from endothelial dysfunction

  • folds in descemet membrane

  • hazy cornea

  • occurs when the inner laer of the cornea (endothelim) fails to properly pump fluid

Neovascularization

• blood vessels growing into cornea

keratic precipitates (KP’s)

Inflammatory deposits on endothelium.

Associated with uveitis.

Can be large greasy clusters of macrophages (mutton-fat KPs)

Fine KPs: Tiny, dust-like spots often indicating non-granulomatous uveitis. 

A granulomatous eye condition involves the formation of small, grainy nodules (granulomas) where white blood cells cluster together to wall off inflammation, infection, or foreign objects

eye layers