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.

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 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.

Patients typically present within one week of surgery with eye pain, photophobia, conjunctivitis, or excessive tear production.

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.

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.

In patients with lymphocytic interstitial pneumonia, these patients may present with lymphadenopathy, enlarged liver, enlarged spleen, enlarged salivary gland, thickening and widening of the extremities of the fingers and toes (clubbing), and breathing symptoms such as shortness of breath and wheezing.

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)

DLK is predominantly associated with Lasik, as the creation of a flap creates a potential space for cells to accumulate. Individuals with atopic conditions with pre-existing allergic conjunctivitis, or ocular rosacea, are more prone to developing the condition after surgery. Some authors have reported that moderate to severe eye allergies and chronic allergic conjunctivitis are an absolute contraindication to the LASIK procedure. This is in distinction to findings of earlier studies. Keratitis can also occur after photorefractive keratectomy (PRK), although because it occurs in the setting of infection, it is distinct from the sterile infiltrates of DLK. DLK can also occur following myopic keratomileusis, in which a disc of corneal tissue is removed, shaped and sutured back into place, although this technique is more historical, having been replaced by Lasik and PRK.

Vernal keratoconjunctivitis (VKC) or spring catarrh is a recurrent, bilateral, and self-limiting inflammation of conjunctiva, having a periodic seasonal incidence.

Symptoms of scleritis include:

- Redness of the sclera and conjunctiva, sometimes changing to a purple hue

- Severe ocular pain, which may radiate to the temple or jaw. The pain is often described as deep or boring.

- Photophobia and tearing

- Decrease in visual acuity, possibly leading to blindness

The pain of episcleritis is less severe than in scleritis. In hyperemia, there is a visible increase in the blood flow to the sclera (hyperaemia), which accounts for the redness of the eye. Unlike in conjunctivitis, this redness will not move with gentle pressure to the conjunctiva.

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.

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.

Corneal involvement in VKC may be primary or secondary due to extension of limbal lesions. Vernal keratopathy includes 5 types of lesions.

1. Punctuate epithelial keratitis.

2. Ulcerative vernal keratitis.

3. Vernal corneal plaques.

4. Subepithelial scarring.

5. Pseudogerontoxon.

Non-specific interstitial pneumonia (NSIP) is a form of idiopathic interstitial pneumonia.

Desquamative interstitial pneumonia is a form of idiopathic interstitial pneumonia featuring elevated levels of macrophages.

Its name is derived from the former belief that these macrophages were pneumocytes that had desquamated.

It is associated with patients with a history of smoking.

Treatment with methylprednisolone has been reported.

It is a characterized by a breakdown or damage of the epithelium of the cornea in a pinpoint pattern, which can be seen with examination with a slit-lamp. Patients may present with non-specific symptoms such as red eye, tearing, foreign body sensation, photophobia and burning.

Secondary keratitis or uveitis may occur with scleritis. The most severe complications are associated with necrotizing scleritis.

Pneumonitis or pulmonitis is an inflammation of lung tissue due to factors other than microorganisms. Those can be radiation therapy of the chest , exposure to medications used during chemo-therapy, the inhalation of debris (ie animal dander), of food particles during vomiting, herbicides or fluorocarbons and some systemic diseases.

It is distinguished from pneumonia on the basis of causation as well as its manifestation since pneumonia can be described as pneumonitis combined with consolidation and exudation of lung tissue due to infection with microorganism.

Most common:

- Chest Pain

- Cough

- Fever

- Shortness of breath

- Joint pain, stiffness, swelling

- Skin nodules

People may not present with all these symptoms or non at all.

Lymphocytic interstitial pneumonia (also called lymphocytic interstitial pneumonitis or LIP) is a syndrome secondary to autoimmune and other lymphoproliferative disorders. Symptoms include fever, cough, and shortness of breath. Lymphocytic interstitial pneumonia applies to disorders associated with both monoclonal or polyclonal gammopathy.

The typical symptoms of UIP are progressive shortness of breath and cough for a period of months. In some patients, UIP is diagnosed only when a more acute disease supervenes and brings the patient to medical attention.

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.

The cause of the scarring in UIP may be known (less commonly) or unknown (more commonly). Since the medical term for conditions of unknown cause is "idiopathic", the clinical term for UIP of unknown cause is idiopathic pulmonary fibrosis (IPF). Examples of known causes of UIP include systemic sclerosis/scleroderma, rheumatoid arthritis, asbestosis, and prolonged use of medications such as nitrofurantoin or amiodarone.