Corneal and Retinal Disorders

Corneal Dystrophies

are inherited eye disorders that affect the cornea. usually inherited as Autosomal dominant traits. Are characterized by deposits in the corneal layers which cause Irregular corneal surface, Decreased vision, Blurred vision, Corneal edema, and Pain or discomfort if blisters rupture

Corneal edema

Develops when the corneal endothelial cells break down causing cloudy cornea, Blurred vision, and Reduced visual clarity

Bullous Keratopathy

formation of blisters on the cornea. Persistent corneal edema may be a cause. These blisters may cause Pain, Discomfort, Irritation, and More blurred vision

1. Keratoconus

2. Fuchs endothelial dystrophy

Main Types of Corneal Dystrophies

Keratoconus

most common type of corneal dystrophy. It is characterized by Cone-shaped protrusion of the cornea. In this condition, the cornea becomes progressively thin and bulges outward. May later cause corneal scarring

Rigid gas-permeable contact lenses

The main treatment for keratoconus. Corrects irregular astigmatism, Improves vision, and Provide better corneal surface for focusing light

Penetrating keratoplasty, or PKP

Surgery for keratoconus when contact lenses are no longer effective

Fuchs Endothelial Dystrophy

a condition involving slow death of endothelial corneal cells, Corneal edema develops, and Vision becomes blurred. Usually affects women more.

Corneal transplant

The only cure for Fuchs Dystrophy

Phototherapeutic Keratectomy (PTK)

s a laser procedure used to treat diseased corneal tissue. Remove corneal opacities, Reduce corneal opacities, Smooth the anterior corneal surface, and Improve functional vision. Contraindicated in patients with Active herpetic keratitis as UV rays may reactivate the latent virus.

Penetrating Keratoplasty (PKP)

Corneal transplantation or Corneal grafting. It involves replacing abnormal corneal tissue with healthy donor corneal tissue. Patients usually describe Eye discomfort rather than acute pain so severe pain should be reported

Anterior Lamellar Keratoplasty (ALK)

a partial-thickness corneal transplant that removes partial stroma, preserving deep stroma, Descemet's, and endothelium.

Deep Anterior Lamellar Keratoplasty

a partial-thickness cornea transplant that replaces diseased or scarred corneal stroma while leaving the patient's healthy inner layer (Descemet's membrane and endothelium) intact. It is primarily used to treat conditions like keratoconus and corneal stromal opacities

Posterior Lamellar Keratoplasty / Endothelial Keratoplasty

replaces only the diseased innermost layers (the endothelium and Descemet's membrane) while leaving the patient's healthy stroma and surface completely intact. Indicated for Fuchs endothelial dystrophy and Bullous keratopathy

Keratoprosthesis

Artificial corneal implants in patients that are not suitable for keratoplasty

Refractive Surgeries

Are elective procedures used to correct refractive errors. They correct Myopia, Hyperopia, and Astigmatism. They work by reshaping the cornea

- Corticosteroid use

- Immunosuppression

- Elevated IOP

Poor Candidates for Refractive Surgery if they have conditions that affect corneal wound healing, such as:

Sensory retina

Retinal pigment epithelium

The two layers most commonly involved in retinal disorders are:

Retinal Detachment

refers to the separation of the retinal pigment epithelium from the neurosensory layer. The retina separates from the layer that supports and nourishes it. An ocular emergency even if there is no pain. Immediate surgical intervention is needed for best outcomes.

1. Rhegmatogenous retinal detachment

2. Traction retinal detachment

3. Combined rhegmatogenous and traction retinal detachment

4. Exudative retinal detachment

Types of Retinal Detachment

Rhegmatogenous Retinal Detachment

the most common type. It occurs when a hole or tear develops in the sensory retina. This allows liquid vitreous to pass through the tear and separate the sensory retina from the retinal pigment epithelium.

Traction Retinal Detachment

occurs because of a pulling force on the retina. This pulling force may come from scar tissue or fibrous bands. The fibrous scar tissue pulls on the delicate retina and causes separation.

Exudative Retinal Detachment

occurs when serous fluid accumulates under the retina from the choroid. This fluid separates the retina without a tear. Possible causes include Uveitis or macular degeneration

Clinical Manifestations of Retinal Detachment

Shade or curtain coming across vision in one eye

Cobweb-like vision

Bright flashing lights

Sudden increase in floaters

Sudden visual changes

Scleral buckle

Vitrectomy

The most common surgical interventions in Traction Retinal detachment are:

Scleral buckle

a procedure where the surgeon compresses the sclera from the outside of the eye. A silicone band or buckle may be used to indent the scleral wall and bring the separated retinal layers back together. The buckle pushes the eye wall inward so the retina can reattach.

Vitrectomy

intraocular procedure used to repair retinal problems. Relieve traction on the retina, Remove vitreous hemorrhage, Remove preretinal membranes, and Help repair retinal detachment

Prone position

Postoperative positioning is very important when a gas bubble is used. The gas bubble must stay over the area of detachment to provide pressure. The patient may need to assume this position to allow the gas bubble to act as a tamponade for the retinal break.

Retinal Vascular Disorders

occur when blood flow through a retinal artery or vein is blocked. Loss of vision may occur due to occlusion of Retinal artery or Retinal vein

Central Retinal Vein Occlusion (CRVO)

occurs when the central retinal vein is blocked. Common in >50 yrs old. may report decreased visual acuity. Vision changes may range from Mild blurring to Severe visual limitation. Fluorescein angiography may show Extensive areas of capillary closure

Branch Retinal Vein Occlusion (BRVO)

a blockage of the small veins that carry blood away from the retina, usually caused by an atherosclerotic artery compressing the vein. This obstruction causes blood and fluid to leak, leading to sudden, painless blurry vision or vision loss in one eye

Central Retinal Artery Occlusion (CRAO)

a true medical emergency—often called a "stroke of the eye". It occurs when a blockage (blood clot or cholesterol plaque) cuts off blood flow to the retina. This causes sudden, profound, and painless vision loss in one eye.

Age-related macular degeneration (AMD)

a condition in which the macula degenerates, gradually causing central vision loss. leading cause of irreversible blindness and visual impairment worldwide. It is characterized by the presence of Drusen beneath the retina and in the macular area which affects vision

Drusen

clusters of debris or waste material that collect under the retina. Small amounts are common in >60 yrs old

Dry AMD

Wet AMD

Types of AMD

Dry AMD

most common type of AMD; causes deposits of yellow-colored extracellular material (drusen) within the macula of the eye, causing possible atrophy of the retina and a gradual loss of central vision. Also called Nonneovascular AMD or Nonexudative AMD

Wet AMD

Abnormal blood vessels grow under the macula and can leak blood and fluid, raising the macula and impairing central vision. As the macula is displaced, straight lines may look wavy. Abrupt or sudden onset, It can cause more severe visual changes.

Choroidal neovascularization

Wet AMD involves abnormal blood vessel growth under the retina within the choroid layer. This condition is called:

Clinical Manifestations of Wet AMD

Straight lines appear crooked

Straight lines appear distorted

Letters in words appear broken

Vision becomes suddenly blurred

Central vision becomes distorted

Diabetic retinopathy

a serious eye complication of long-term diabetes mellitus. It occurs when diabetes damages the blood vessels of the retina.

Cytomegalovirus Retinitis

inflammation of the retina caused by cytomegalovirus. It is commonly associated with AIDS. The retina may become Thin, Atrophic, Susceptible to tears, or Susceptible to breaks

Hemorrhagic type

Brushfire type

Granular type

Three Forms of CMV Retinitis

Hemorrhagic type

Large areas of white necrotic retina. Associated retinal hemorrhage. This type involves both necrosis and bleeding in the retina.

Brushfire type

A yellow-white margin begins at the edge of burned-out atrophic retina. The inflammation expands over time. If untreated, it may involve the entire retina. The spread looks like a brushfire, gradually expanding from the damaged retinal area.

Granular Type

White granular lesions appear in the peripheral retina. Lesions gradually expand. This type begins in the periphery of the retina.

Ganciclovir

Foscarnet

Cidofovir

Common medication for CMV Retinitis

Cotton-wool spots

Retinal hemorrhages

Retinal edema

Retinal exudates

Exudates clustered around the macula

Severe hypertensive retinopathy may show:

Cotton-Wool Spots

White, fluffy retinal lesions caused by nerve fiber layer ischemia.