Glossary

EYE CONDITIONS AND DISEASES

A
Accommodative
Accommodative stress which is caused by pronounced near point requirements, resulting in complaints such as eyestrain, headaches, red or watery eyes, near blur or even distance blur.

Amblyopia (Lazy eye)
The condition of the eye where the vision of the eye cannot be corrected by the spectacles and there is no pathology.

Astigmatism
It is condition in which the refracting surfaces of an eye consist of two principal powers. That is the eye’s optical system is incapable of forming a point image for a point object.

B
Blepharitis
Blepharitis is a common inflammatory condition that affects the eyelids caused by staphylococcal infection mainly due to poor hygiene. It presents as crusting and flaking at the base of the eyelashes

C
Cataract
A condition where there are opacities on the crystalline lens which interfere with vision.

Chalazion
This is a chronic inflammatory condition caused by the blockage of the meibomian gland and stagnations of sebaceous secretions. The lesion is always not painful.

Colour vision deficiency
This is the colour vision defect that causes the person to confuse colours or unable to recognize different colours. This condition can be congenital or acquired.

Conjunctivitis
Conjunctivitis is an infection of the conjunctiva causing tearing, redness or itching of the eyes. The three most common types of conjunctivitis are: viral, allergic, and bacterial.

Convergence insufficiency
This is a binocular anomaly in which there is high exophoria at near, resulting in complaints of headaches, eyestrain which occur usually after prolonged reading or near work.

Corneal abrasion
Condition caused by traumatic insult to the cornea resulting in red eye, light sensitivity and eye irritation.

D
Diabetic retinopathy
These are changes in the retina that occur in a person with diabetes. The changes include cotton wool spots, hard exudates, micro-aneurisms and hemorrhages.

Dry eyes
Dry eye syndrome is usually caused by a problem with the quality of the tear film that lubricates the eyes. The common complaints are burning eyes, foreign body sensation and irritation of the eyes.

E
Ectropion
Patients with ectropion have a sagging lower eyelid that leaves the eye exposed and dry. It is caused by a lack of tone of the delicate muscles that hold the lid taut against the eye.

Entropion
This is a condition where an eyelid turns inward. It usually stems from a muscle spasm; however, it can also be caused by scarring from trauma or inflammation from certain diseases that involve the eyelids.

F
Floaters
These are spots that occur when the vitreous becomes partly liquefied. These tend to occur in myopes and older people. These fine vitreous opacities cast shadows on the retina. Patients describe them as cobwebs, spots or rings.

G
Glaucoma/ Ocular hypertension
This is a condition caused by high intraocular pressure which causes damage to optic nerve fibers entering the optic nerve leading to loss of vision.

H
Hordeolum (internal)
This is an abscess of the eyelid caused by acute staphylococcal infection of the Meibomian gland. The lesion may enlarge and discharge through the conjunctiva or the skin.

Hyperopia / Farsighted /
A refractive anomaly in which the parallel rays of light converge to focus behind the retina when looking at distance (accommodation is relaxed).

K
Keratitis
This is the inflammation of the cornea caused by a variety of bacteria, viruses, fungi or interruption of sensory supply to the cornea.

Keratoconus
A protrusion and thinning of the cornea which happens in early childhood and slowly progresses throughout life. Contact lenses are used as optical correction.

L
Lazy eye (see amblyopia)

Learning-related vision problems
This refers to a group of learning disorders found in children and young adults, mainly caused by developmental and perceptual motor anomalies.

M
Macula degeneration
This is the disease of the macular area, with a gradual impairment of vision over months to years. This condition is characterized by yellow spots on the macula or drusen

Migraine with Aura / Ocular migraine
This refers to a headache which is accompanied by a feeling of nausea and a visual aura or scintillating scotoma which is confined to one side of the visual field. This is due to the constriction of the branches of the carotid artery supplying the visual cortex.

Myopia/ Nearsighted
A refractive anomaly in which the parallel rays of light converge to a focus in front of the retina when looking at distance (accommodation relaxed).

N
Nearsighted (see myopia)

Nystagmus
This is a repetitive, involuntary conjugate movement of the eyes. These eye movements have either equal velocity and amplitude in both directions or have a slow movement in one direction and a fast movement in the other direction.

O
Ocular allergies
These are inflammations of the conjunctiva due to allergens in the environment. They are more common in children and the most common complain is itchy eyes.

P
Pinguecula
A pinguecula is a benign, yellowish growth that forms on the conjunctiva. They usually grow near the cornea on the nasal side. Pingueculae are thought to be caused by ultraviolet light and are most common among people who spend a great deal of time outdoors.

Presbyopia
This is the ocular condition in which the person around 45 years of age start having receded a near point of accommodation. This receded near point of accommodation makes near work difficult and the near spectacles have to be prescribed.

Pterygium
Pterygium is a raised, wedge-shaped growth of the conjunctiva. It is most common among those who live in tropical climates or spend a lot of time in the sun.

Ptosis
This is the drooping of the upper eyelid which occurs for several reasons such as: disease, injury, birth defect, previous eye surgery and age.

R
Retinal detachment
This is a condition in which the sensory retina becomes detached from the pigment epithelium, leaving the epithelium attached to the choroids. The complaints will include a curtain or shadow across the patient’s vision.

Retinitis pigmentosa
A diffuse retinal dystrophy affecting the rods, it is characterized by the loss of peripheral vision and progressive loss of the rod function

Retinoblastoma
This is the cancer of the eye mainly affecting children in their first few years of life. It is characterized by leukoria (white pupil reflex) and strabismus.

S
Strabismus (squint) or Crosses eyes
A manifest deviation of the eye which may be in one eye (unilateral) or in either eye (alternating). It is usually classified as exotropia (eye turn out) or esotropia (eye turns in).

Sty (External Hordeolum) An acute staphylococcal abscess of a lash follicle and its associated gland of Zeiss or Moll which usually affects children.

Subconjunctival haemorrhage
The rupture of a conjunctival vessel, usually caused by blunt trauma or severe cough and it clears within three days.

U
Uveitis
A chronic or acute inflammation of the uveal tract; namely the iris, ciliary body or choroid)