Corneal ulcers are extremely painful due to nerve exposure, and can cause tearing, squinting, and vision loss of the eye. There may also be signs of anterior uveitis, such as miosis (small pupil), aqueous flare (protein in the aqueous humour), and redness of the eye. An axon reflex may be responsible for uveitis formation—stimulation of pain receptors in the cornea results in release inflammatory mediators such as prostaglandins, histamine, and acetylcholine.

Sensitivity to light (photophobia) is also a common symptom of corneal ulcer.

Corneal ulcer, or ulcerative keratitis, is an inflammatory or more seriously, infective condition of the cornea involving disruption of its epithelial layer with involvement of the corneal stroma. It is a common condition in humans particularly in the tropics and the agrarian societies. In developing countries, children afflicted by Vitamin A deficiency are at high risk for corneal ulcer and may become blind in both eyes, which may persist lifelong. In ophthalmology, a corneal ulcer usually refers to having an infectious cause while the term corneal abrasion refers more to physical abrasions.

Signs and symptoms of corneal abrasion include pain, trouble with bright lights, a foreign-body sensation, excessive squinting, and reflex production of tears. Signs include epithelial defects and edema, and often redness of the eye. The vision may be blurred, both from any swelling of the cornea and from excess tears. Crusty buildup from excess tears may also be present.

Symptoms include recurring attacks of severe acute ocular pain, foreign-body sensation, photophobia (i.e. sensitivity to bright lights), and tearing often at the time of awakening or during sleep when the eyelids are rubbed or opened. Signs of the condition include corneal abrasion or localized roughening of the corneal epithelium, sometimes with map-like lines, epithelial dots or microcysts, or fingerprint patterns. An epithelial defect may be present, usually in the inferior interpalpebral zone.

Most cases of recurrent corneal erosion are acquired. There is often a history of recent corneal injury (corneal abrasion or ulcer), but also may be due to corneal dystrophy or corneal disease. In other words, one may suffer from corneal erosions as a result of another disorder, such as map-dot fingerprint dystrophy. Familial corneal erosions occur in dominantly inherited recurrent corneal erosion dystrophy (ERED) in which COL17A1 gene is mutated..

Neurotrophic keratitis (NK) is a degenerative disease of the cornea caused by damage of the trigeminal nerve, which results in impairment of corneal sensitivity, spontaneous corneal epithelium breakdown, poor corneal healing and development of corneal ulceration, melting and perforation.

Neurotrophic keratitis is classified as a rare disease, with an estimated prevalence of less than 5 in 10,000 people in Europe. It has been recorded that on average, 6% of herpetic keratitis cases may evolve to this disease, with a peak of 12.8% of cases of keratitis due to herpes zoster virus.

The diagnosis, and particularly the treatment of neurotrophic keratitis are the most complex and challenging aspects of this disease, as a satisfactory therapeutic approach is not yet available.

Acutely or at the early sign includes painful, photophobic, red and watery eye. This is due to active corneal inflammation resulting in vascular invasion and stromal necrosis which can be diffuse or localized. This cause the pinkish discoloration of what was a clear transparent normal corneal tissue (called "Salmon patch of Hutchinson").

Chronically or the end result will cause blurring of vision secondary to corneal stromal scarring, presence of ghost vessel and thinning of the cornea especially if it involves the visual axis.

The person experiences pain and a sudden severe clouding of vision, with the cornea taking on a translucent milky-white appearance known as a corneal hydrops.

Corneal perforation is an anomaly in the cornea resulting from damage to the corneal surface. A corneal perforation means that the cornea has been penetrated, thus leaving the cornea damaged.

The cornea is a clear part of the eye which controls and focuses the entry of light into the eye. Damage to the cornea due to corneal perforation can cause decreased visual acuity.

Skin ulcers appear as open craters, often round, with layers of skin that have eroded. The skin around the ulcer may be red, swollen, and tender. Patients may feel pain on the skin around the ulcer, and fluid may ooze from the ulcer. In some cases, ulcers can bleed and, rarely, patients experience fever. Ulcers sometimes seem not to heal; healing, if it does occur, tends to be slow. Ulcers that heal within 12 weeks are usually classified as acute, and longer-lasting ones as chronic.

Ulcers develop in stages. In stage 1 the skin is red with soft underlying tissue. In the second stage the redness of the skin becomes more pronounced, swelling appears, and there may be some blisters and loss of outer skin layers. During the next stage, the skin may become necrotic down through the deep layers of skin, and the fat beneath the skin may become exposed and visible. In stage 4, deeper necrosis usually occurs, the fat underneath the skin is completely exposed, and the muscle may also become exposed. In the last two stages the sore may cause a deeper loss of fat and necrosis of the muscle; in severe cases it can extend down to bone level, destruction of the bone may begin, and there may be sepsis of joints.

Chronic ulcers may be painful. Most patients complain of constant pain at night and during the day. Chronic ulcer symptoms usually include increasing pain, friable granulation tissue, foul odour, and wound breakdown instead of healing. Symptoms tend to worsen once the wound has become infected.

Venous skin ulcers that may appear on the lower leg, above the calf or on the lower ankle usually cause achy and swollen legs. If these ulcers become infected they may develop an unpleasant odour, increased tenderness and redness. Before the ulcer establishes definitively, there may be a dark red or purple skin over the affected area as well as a thickening, drying, and itchy skin.

Although skin ulcers do not seem of great concern at a first glance, they are worrying conditions especially in people suffering from diabetes, as they are at risk of developing diabetic neuropathy.

Ulcers may also appear on the cheeks, soft palate, the tongue, and on the inside of the lower lip. These ulcers usually last from 7 to 14 days and can be painful.

An ulcer is a sore on the skin or a mucous membrane, accompanied by the disintegration of tissue. Ulcers can result in complete loss of the epidermis and often portions of the dermis and even subcutaneous fat. Ulcers are most common on the skin of the lower extremities and in the gastrointestinal tract. An ulcer that appears on the skin is often visible as an inflamed tissue with an area of reddened skin. A skin ulcer is often visible in the event of exposure to heat or cold, irritation, or a problem with blood circulation. They can also be caused due to a lack of mobility, which causes prolonged pressure on the tissues. This stress in the blood circulation is transformed to a skin ulcer, commonly known as bedsores or decubitus ulcers. Ulcers often become infected, and pus forms.

Corneal abrasion is a scratch to the surface of the cornea of the eye. Symptoms include pain, redness, light sensitivity, and a feeling like a foreign body is in the eye. Most people recover completely within three days.

Most cases are due to minor trauma to the eye such as that which can occur with contact lens use or from fingernails. About 25% of cases occur at work. Diagnosis is often by slit lamp examination after fluorescein dye has been applied. More significant injuries like a corneal ulcer, globe rupture, recurrent erosion syndrome, and a foreign body within the eye should be ruled out.

Prevention includes the use of eye protection. Treatment is typically with antibiotic ointment. In those who wear contact lenses a fluoroquinolone antibiotic is often recommended. Paracetamol (acetaminophen), NSAIDs, and eye drops such as cyclopentolate that paralysis the pupil can help with pain. Evidence does not support the usefulness of eye patching for those with simple abrasions.

About 3 per 1,000 people are affected a year in the United States. Males are more often affected than females. The typical age group affected is those in their 20s and 30s. Complications can include bacterial keratitis, corneal ulcer, and iritis. Complications may occur in up to 8% of people.

Interstitial keratitis (IK) is corneal scarring due to chronic inflammation of the corneal stroma. Interstitial means space between cells i.e. corneal stroma which lies between the epithelium and the endothelium. Keratitis means corneal inflammation.

Corneal hydrops or corneal rupture is an uncommon complication seen in people with advanced keratoconus or other corneal ectatic disorders, and is characterized by stromal edema due to leakage of aqueous humor through a tear in Descemet's membrane. Although a hydrops usually causes increased scarring of the cornea, occasionally it will benefit a patient by creating a flatter cone, aiding the fitting of contact lenses. Corneal transplantation is not usually indicated during corneal hydrops.

The symptoms of fungal keratitis are blurred vision, a red and painful eye that does not improve when contact lenses are removed, or on antibiotic treatment, increased sensitivity to light (photophobia), and excessive tearing or discharge. The symptoms are markedly less as compared to a similar bacterial ulcer.

Signs: The eyelids and adnexa involved shows edema and redness, conjuctiva is chemosed. Ulcer may be present. It is a dry looking corneal ulcer with satellite lesions in the surrounding cornea. Usually associated with fungal ulcer is hypopyon, which is mostly white fluffy in appearance. Rarely, it may extend to the posterior segment to cause endophthalmitis in later stages, leading to the destruction of the eye. (Note: Fungal endophthalmitis is extremely rare)

This classic herpetic lesion consists of a linear branching corneal ulcer (dendritic ulcer). During eye exam the defect is examined after staining with fluorescein dye. The underlying cornea has minimal inflammation.

Patients with epithelial keratitis complain of foreign-body sensation, light sensitivity, redness and blurred vision.

Focal or diffuse reduction in corneal sensation develops following recurrent epithelial keratitis.

In immune deficient patients or with the use of corticosteroids the ulcer may become large and in these cases it is called geographic ulcer.

"Acanthamoeba" keratitis is a rare disease in which amoebae invade the cornea of the eye. It may result in permanent visual impairment or blindness.

The cornea, an avascular tissue, is among the most densely innervated structures of the human body. Corneal nerves are responsible for maintaining the anatomical and functional integrity of the cornea, conveying tactile, temperature and pain sensations, playing a role in the blink reflex, in wound healing and in the production and secretion of tears.

Most corneal nerve fibres are sensory in origin and are derived from the ophthalmic branch of the trigeminal nerve. Congenital or acquired ocular and systemic diseases can determine a lesion at different levels of the trigeminal nerve, which can lead to a reduction (hypoesthesia) or loss (anesthesia) of sensitivity of the cornea.

The most common causes of loss of corneal sensitivity are viral infections (herpes simplex and herpes zoster ophthalmicus), chemical burns, physical injuries, corneal surgery, neurosurgery, chronic use of topical medications, or chronic use of contact lenses.

Possible causes also include systemic diseases such as diabetes, multiple sclerosis or leprosy.

Other, albeit less frequent, potential causes of the disease are: intracranial space-occupying lesions such as neuroma, meningioma and aneurysms, which may compress the trigeminal nerve and reduce corneal sensitivity.

Conversely, congenital conditions that may lead to this disorder are very rare.

Herpetic simplex keratitis, also known as herpetic keratoconjunctivitis and herpesviral keratitis, is a form of keratitis caused by recurrent herpes simplex virus (HSV) infection in the cornea.

It begins with infection of epithelial cells on the surface of the eye and retrograde infection of nerves serving the cornea. Primary infection typically presents as swelling of the conjunctiva and eyelids (blepharoconjunctivitis), accompanied by small white itchy lesions on the corneal surface. The effect of the lesions varies, from minor damage to the epithelium (superficial punctate keratitis), to more serious consequences such as the formation of dendritic ulcers. Infection is unilateral, affecting one eye at a time. Additional symptoms include dull pain deep inside the eye, mild to acute dryness, and sinusitis. Most primary infections resolve spontaneously in a few weeks. Healing can be aided by the use of oral and topical antivirals.

Subsequent recurrences may be more severe, with infected epithelial cells showing larger dendritic ulceration, and lesions forming white plaques. The epithelial layer is sloughed off as the dendritic ulcer grows, and mild inflammation (iritis) may occur in the underlying stroma of iris. Sensation loss occurs in lesional areas, producing generalised corneal anaesthesia with repeated recurrences. Recurrence can be accompanied by chronic dry eye, low grade intermittent conjunctivitis, or chronic unexplained sinusitis. Following persistent infection the concentration of viral DNA reaches a critical limit. Antibody responses against the viral antigen expression in the stroma can trigger a massive immune response in the eye. The response may result in the destruction of the corneal stroma, resulting in loss of vision due to opacification of the cornea. This is known as immune-mediated stromal keratitis.

HSV infection is very common in humans. It has been estimated that one third of the world population have recurrent infection. Keratitis caused by HSV is the most common cause of cornea-derived blindness in developed nations. Therefore, HSV infections are a large and worldwide public health problem. The global incidence (rate of new disease) of herpes keratitis is roughly 1.5 million, including 40,000 new cases of severe monocular visual impairment or blindness each year.

Corneal perforation can be diagnosed by using the Seidel test. Any aqueous leakage is revealed during the Seidel test confirms corneal perforation. A fluorescence strip is wiped over the wound. If the clear aqueous humor from the eye runs through the yellow stain, the patient tests positive for corneal perforation.

Corneal neovascularization (CNV) is the in-growth of new blood vessels from the pericorneal plexus into avascular corneal tissue as a result of oxygen deprivation. Maintaining avascularity of the corneal stroma is an important aspect of corneal pathophysiology as it is required for corneal transparency and optimal vision. A decrease in corneal transparency causes visual acuity deterioration. Corneal tissue is avascular in nature and the presence of vascularization, which can be deep or superficial, is always pathologically related.

Corneal neovascularization is a sight-threatening condition that can be caused by inflammation related to infection, chemical injury, autoimmune conditions, post-corneal transplantation, and traumatic conditions among other ocular pathologies. Common causes of CNV within the cornea include trachoma, corneal ulcers, phylctenular keratoconjunctivitis, rosacea keratitis, interstitial keratitis, sclerosing keratitis, chemical burns, and wearing contact lenses for over-extended periods of time. Superficial presentations of CNV are usually associated with contact lens wear, while deep presentations may be caused by chronic inflammatory and anterior segment ocular diseases.

Corneal neovascularization is becoming increasingly common worldwide with an estimated incidence rate of 1.4 million cases per year, according to a 1998 study by the Massachusetts Eye and Ear Infirmary. The same study found that the tissue from twenty percent of corneas examined during corneal transplantations had some degree of neovascularization, negatively impacting the prognosis for individuals undergoing keratoplasty procedures.

In the United States, it is nearly always associated with contact lens use, as "Acanthamoeba" can survive in the space between the lens and the eye. To prevent the condition, contact lenses must be properly disinfected before wearing, and should be removed when swimming or surfing.

However, there have been many cases of "Acanthamoeba" in those who do not wear contact lenses, elsewhere in the world.

Infectious keratitis can be bacterial, fungal, viral, or protozoal. Remarkable differences in presentation of the patient allows presumptive diagnosis by the eye care professional, helping in institution of appropriate anti-infective therapy.

Venous ulcers (venous insufficiency ulceration, stasis ulcers, stasis dermatitis, varicose ulcers, or ulcus cruris) are wounds that are thought to occur due to improper functioning of venous valves, usually of the legs (hence leg ulcers). They are the major occurrence of chronic wounds, occurring in 70% to 90% of leg ulcer cases. Venous ulcers develop mostly along the medial distal leg, and can be very painful with significant effects on quality of life.

Edema and fibrinous exudate leads to fibrosis of subcutaneous tissues with localized pigment loss and dilation of capillary loops. This is called atrophic blanche. This can occur around ankles and gives an appearance of inverted champagne bottle to legs. Large ulcers may encircle the leg.

Lymphedema results from obliteration of superficial lymphatics. There is hypertrophy of overlying epidermis giving polypoid appearance, known as lipodermatosclerosis.