The lesions of the eye can lead to abnormal or damage of your eye and there is various form of eye lesion including:
Congenital lesions of the eye
There is the following form of lesions of the eye, including:
Retrolental fibroplasia
This is also known as retinopathy of prematurity. It is a developmental disorder that occurs in premature infants who have been given oxygen therapy at birth.
The basic defect includes developmental prematurity of the retinal blood vessels that are extremely sensitive to a high dose of oxygen therapy.
The peripheral portion of the retina is incompletely vascularized and exposure to oxygen finally results in vaso-obliteration in such infants.
But upon stoppage of oxygen therapy, there is an occurrence of neovascularization, cicatrisation and retinal detachment.
Retinitis pigmentosa
This includes a group of systemic and ocular diseases of unknown aetiology, characterised by degeneration of the retinal pigment epithelium.
The various inheritance patterns include autosomal dominant, autosomal recessive trait or sex-linked recessive trait. The earliest clinical feature is night blindness due to loss of rods and that may progress to total blindness later on.
Microscopy: Photoreceptor layer of the retina shows disappearance of rods and cones, degeneration of pigment epithelium and ingrowth of the glial membrane on the optic disc.
Inflammatory conditions of the eye (Lesions of the eye)
Inflammatory conditions of the eye are classified according to the tissue affected. It can be described in the following topic:
- Uveitis
- Stye
- Chalazion
- Endophthalmitis-panophthalmitis
- Conjunctivitis and keratoconjunctivitis
- Trachoma
Uveitis
It is the term given for ocular inflammation of the uveal tract, which is the most vascular tissue of the eye. Uveitis is further divided into 2 types:
Granulomatous uveitis
The number of chronic granulomatous conditions caused by bacteria like tuberculosis, leprosy, syphilis. viruses like CMV disease, herpes zoster fungi like aspergillosis, blastomycosis, phycomycosis, histoplasmosis and certain parasites like toxoplasmosis, onchocerciasis.
Sympathetic ophthalmia
This is also known as sympathetic uveitis. The condition may result from an auto sensitivity reaction to injured uveal tissue. It leads to a severe visual loss in both eyes if not diagnosed and treated early.
Microscopically, granulomatous lesions consisting of epithelioid cells and lymphocytes affecting both the eyes seen. Necrosis and neutrophilic or plasma cell infiltration are absent.
A stye (Hordeolum)
This is an acute suppurative inflammation of the sebaceous glands of Zeis, the apocrine glands of Moll and the eyelash follicles (external hordeolum). But the less common ‘internal hordeolum’ is an acute suppurative inflammation of the meibomian glands.
Chalazion
It is a very common chronic inflammatory process involving the meibomian glands. It occurs due to obstruction to the drainage of secretions.
Inflammation begins with the destruction of meibomian glands and duct and finally affects the tarsal plate.
Microscopically, the appearance of a chronic inflammatory granuloma located in the tarsus and contains fat globules at the centre of the granulomas that signify the appearance of a lymphogranuloma.
Endophthalmitis-panophthalmitis
Endophthalmitis is an acute suppurative intraocular inflammation. But panophthalmitis is inflammation of different structures such as the retina, choroid and sclera and extending to the orbit.
The exogenous infection is due to bacteria, viruses or fungi introduced into the eye during an accidental or surgical perforating wound.
Whereas, endogenous agents include opportunistic infections that may cause endophthalmitis via haematogenous routes such as candidiasis, toxoplasmosis, nocardiosis, aspergillosis and cryptococcosis.
Upon healing, synechiae may develop i.e. adhesions between two iris and cornea (anterior synechiae), or between iris and the anterior surface of the lens (posterior synechiae).
Conjunctivitis & keratoconjunctivitis
The conjunctiva and cornea are constantly exposed to various types of physical, microbial (bacteria, fungi, and viruses), chemical, and allergic agents so more susceptible to develop acute, subacute and chronic inflammation.
In the acute stage, there is corneal oedema and infiltration by inflammatory cells, affecting the transparency of the cornea.
In the more chronic form of inflammation, there is a proliferation of small blood vessels (artery and vein) in the normally avascular cornea and infiltration by lymphocytes and plasma cells (pannus formation).
Trachoma
Trachoma is caused by C. trachomatis. In the early stage of infection, the causative agent can be recognised in the smears by the intracytoplasmic inclusion bodies formed by the proliferating microorganisms within the cells.
Later, the conjunctiva thickens due to dense chronic inflammatory cell infiltration along with lymphoid follicles and macrophages. Finally, extensive corneal and conjunctival cicatrisation accounting for blindness is seen in trachoma.
Vascular lesions of the eye
- Diabetic retinopathy
- Hypertensive retinopathy
- Retinal infarcts
Diabetic retinopathy (Lesions of the eye)
It is one of the important causes of blindness and related to the degree and duration of glycaemic control. The condition develops in more than 60 per cent of diabetics 15-20 years aged after the onset of disease and around 2 per cent of diabetics causes blindness.
The risk is greater in type 1 diabetes mellitus than in type 2 diabetes mellitus, but clinically there are more patients with diabetic retinopathy due to type 2.
Histology: two types of changes are seen in diabetic retinopathy.
Background (non-proliferative) retinopathy
Basement membrane shows varying thickness, Degeneration of pericytes, Capillary microaneurysms, Waxy exudates accumulate, dot and blot haemorrhages etc.
Proliferative retinopathy (retinitis proliferans)
Neovascularization of the retina, vitreous haemorrhages, Proliferation of astrocytes and fibrous tissue, retinal detachment and blindness.
Hypertensive retinopathy (Lesions of the eye)
In this diameter of retinal arterioles reduced leading to retinal ischaemia. It happens at malignant hypertension and in toxaemia of pregnancy.
Arteriolar wall thickening like onion skin with narrowing of the lumina is seen. Features include arteriolar narrowing due to arteriolosclerosis, Flame-shaped haemorrhages, Cotton-wool spots i.e. fluffy white bodies in the superficial layer of the retina, Microaneurysms.
Retinal infarcts
Infarcts of the retina may result either from thrombosis or embolism in the central artery of the retina, causing ischaemic necrosis of the inner two-thirds of the retina.
But, occlusion of the posterior ciliary arteries causes ischaemia of the inner photoreceptor layer only. The usual causes of thrombosis and embolism include atherosclerosis, hypertension and diabetes. Occlusion of the central retinal vein produces hemorrhagic infarction of the entire retina.