Basics in Ophthalmic Assisting Manual - Chapter 15

Print Manual

Ophthalmic Terminologies


Studying medical terminology is very similar to learning a new language. The words first sound strange and complicated, although they may stand for commonly known English terms. The terms otalgia, meaning ear ache and ophthalmologist meaning eye doctor are examples. Medical terms are very much like individual jigsaw puzzles. They are constructed of small pieces that make each word unique, but the pieces can be used in different combinations in other words as well. Some medical terms are pronounced alike but are spelled differently, which accounts for their different meanings. Even when the terms are spelled correctly, terms can be misunderstood because of incorrect pronunciation. In this unit the OA learns the medical terms, understands their meaning and usees them appropriately.

  • Eye Ball - The globe or ball of the eye
  • Proptosis - Protrusion of the eyeball
  • Eyelid - Upper lid and lower lid, these two structures cover the eye from the front
  • Cornea - Clear circular transparent portion of the external coat of the eyeball
  • Micro cornea - Cornea size smaller than normal
  • Megalo cornea-Cornea size larger than the normal
  • Lacrimation - Increased tear production due to reflex sensory stimulation
  • Photophobia - Sensitivity to light
  • Hypopyon - Pus in the anterior chamber
  • Leucoma - Opacity of cornea
  • Adherent leucoma
    • Adhesion of a part of the iris to a white corneal scar
  • Alkali burns
    • Corneal burn caused by alkali chemicals such as sodium hydroxide (caustic soda), potassium hydroxide (caustic potash) or calcium hydroxide (slaked lime)
  • Bullous keratopathy
    • Blister like elevation of the corneal epithelium. It results from excess fluid in the stroma and epithelium due to loss of the dehydrating mechanism of the cornea, and is usually caused by damage to the endothelial cells. It may result in blindness and pain
  • Keratomalacia
    • Softening of the cornea often occurring in sever vitamin A deficiency
  • Herpes zoster ophthalmicus
    • Reactivation of the chicken pox virus affecting the skin over the distribution of the fifth nerve, which may produce corneal ulcers, iritis and secondary glaucoma
  • Arcus senilis
    • It is a grayish white circular line of lipid deposition in the cornea near the limbus, usually seen in aged persons. Harmless
  • Keratoconus
    • In this condition central or paracentral cornea undergoes progressive thinning and bulging. Patient develops high astigmatism
  • Limbus
      It is a structure at the junction of the cornea and conjunctiva
  • Keratoplasty (corneal grafting)
    • Corneal transplantation is a procedure where abnormal host corneal tissue is replaced by healthy donor corneal tissue
  • Choroid - is a highly vascular coat of the eye that nourishes the outer layer of the retina.
  • Sclera - is the hard, firm, fibrous outer coat of the eye which is contiguous to the cornea.
  • Iris - coloured membrane in front of lens usually brownish black coloured.
  • Pupil - is circular opening in the center of iris.


  • Anterior segment - referring to the front part of the eye.
  • Angle of the anterior chamber is the angle that lies between the iris and the cornea and through which the aqueous fluid flows out of the eye.
  • Gonioscopy - examination of the angle of the anterior chamber.
  • Anterior chamber - the portion of the eye lying between the cornea and the iris.
  • Posterior chamber - is a triangular space between the back of iris and the anterior surface of the lens.


The lens of the eye is a transparent biconvex structure situated between the iris and the vitreous.

  • Cataract - an opacity of the crystalline lens.
  • Hypermature cataract - a cataract in which the lens of the eye becomes white and opaque, and hard.
  • Mature cataract - an opacity of lens of the eye that has become completely opaque
  • Nuclear cataract - a cataract largely confined to the central portion of the lens, the nucleus.
  • Senile cataract - an opacity of the lens occurring in the aged.
  • Traumatic cataract - a cataract following any injury to the eye


  • Mucous membrane that lines the eyelids and wraps around the front part of the eyeball to end at the limbal junction of the cornea.
  • Conjunctival sac - the potential space, lined by conjunctiva, between the eyelids and the eyeball; cul - de - sac.
  • Dacryocystorhinstomy (DCR) - a communi-cation is made between nasal mucosa and nasal lacrimal sac flap.
  • Epilation - the mechanical removal of eyelashes or cilia by the roots as performed in the removal of misdirected eyelashes.
  • Eversion of the eyelid - the folding back of the eyelid.
  • Extraction - removal. In the eye it refers to the surgical removal of the lens (cataract removal).
  • Filtering procedure - an operation for the release of aqueous into the subtenon or subconjunctival space by fistulisation through the sclera.
  • Fundus - inside of the eye. Primarily the retina, the macula, the optic disc, and the retinal vessels that can be seen with an ophthalmoscope.
  • Implant - an artificial insert placed in the eye, socket or orbit. Also introcular lens implant.
  • Lacrimal gland - a gland that secretes tears; it lies in the upper outer angle of the orbit.
  • Limbus : the annular border between the clear cornea and the opaque scleral - conjunctival area
  • Orbit - the bony cavity containing the eye, which is formed by the frontal sphenoid, ethmoid, nasal, lacrimal and maxillary bones.
  • Panretinal photocoagulation (PRP) - complete laser photocoagulation of the retina.
  • Peripheral iridectomy - a section of iris is excised so that aqueous can drain from the posterior chamber to the anterior chamber.


  • triangular fold of growing membrane that may extend over the cornea from the white of the eye. It occurs most frequently in persons exposed to dust or wind over a long period of time.


  • A temporary or permanent surgical union of the upper and lower lid margins. It may be temporal (lateral) nasal (medial) or completes.
  • Vitreous is a jelly like substance behind the lens and in front of the retina.
  • Vitrectomy is a surgical procedure to remove a portion of vitreous from the eye.
  • Retina is a layer of sensory receptors for light and is composed of rods and cones.
  • Retinal detachment is separation of the retina in which the anterior sensory layer detaches from the posterior pigment layer.
  • Retinopathy is a general term denoting any pathological occurrence in the retina.
  • Diabetic retinopathy is retinopathy seen in diabetic patients.
  • Hypertensive retinopathy is retinopathy seen in hypertensive patients.
  • Retinopathy of prematurity is an obliteration of developing blood vessels in an immature retina initially caused in the premature newborn by a high concentration of oxygen.
  • Buckling - means operating for retinal detachment by resecting a portion of the sclera and implantation of foreign material to indent the outer coats of the eye.

Eye muscles

  • Medial - means towards the center
  • Lateral - means away from the center
  • Superior - means upper
  • Inferior - means lower
  • Intraocular - means within the eye

Intraocular pressure

The pressure of the fluid within the eye.


Glaucoma is characterised by a sustained elevation of intraocular pressure.

Aseptic Environment

Is one that is free from bacteria and pathogenic spores.


Is the killing of all living organisms including spores.


Is the killing of most pathogenic organisms but not necessarily spores.


Is a piece of equipment that provides heat and moisture under high pressure to sterilise materials.


Anaesthetics, local given by injection; only the area infiltrated is locally treated. Agents employed in ophthalmology include procaine and lidocine (Xylocaine).

  • Antibacterial drugs - originally derive from bacteria and fungus molds. Synthetic antibiotics are common.
  • Cyclogyl - a rapid onset, short - acting synthetic drug that causes mydriasis and cycloplegia after being dropped into the eye.
  • Used prior to refraction, especially in children.

Miscellaneous terminology

Abscess - localized area of inflammation.
Bell's phenomenon - upward - and - outward deviation of the eyes occurring in sleep or with forcible closure of the eyelids.


The phenomenon of bending light as it passes from one transparent medium to another of different density is known as refraction.

Refractive Index

The refractive power of a substance in comparison with that of air is spoken of as its refractive index.


The process of directing the visual axis of the two eyes inward to a new point.

Cross cylinder

A lens consisting of two cylinders of equal power, one being plus, the other being minus, set 90 degrees apart.


A drug often used in refraction, which temporarily places the ciliary muscle at rest and dilates the pupil.

Depth perception

Ability to perceive the solidity of objects and their relative positions in space; also called stereoscopic vision.


The outward rotations of the two eyes to see in the distance.


Irregularly scattered light that interferes with the focused retinal picture and reduces visual acuities.

Automatic refractors

An instrument whose purpose is to provide an accurate assessment of the refractive error of the eye.


When parallel rays of light strike a physiologically normal eye they are refracted to converge upon the retina where they focus, forming a circle of least diffusion, with the eye in the state of rest (without accommodation).


Parallel rays of light are not focused upon the retina with the eye in the state of rest, such as in refractive error.


Eye is relatively short; images are formed behind the retina. Patients will complain of difficulty while doing near work and reading.


The eye is relatively long; images are formed in front of retina. Patient will complain of difficulty seeing distant objects.


A refractive error that prevents light rays coming to a single focus on the retina due to different degree of refraction in various meridians of the eye.


Is a condition in which there is a difference in the refractive error of the two eyes.


If the difference in the refractive error of the two eyes is very large, image of unequal size will appear on the retina and be transferred to the brain.


is the condition in which the crystalline lens is absent from the pupillary area.


Is a condition in which the ability to accommodate for near vision decreases because of loss of elasticity of the crystalline lens of the eye and weakness of the ciliary muscles. Condition is seen above the age of 40 years.

Visual axis

A line that connects a point in space with the fovea centralis of retina.


Prescribed glasses that are worn to correct refractive error.

Contact lenses

Are thin shells of transparent plastic designed to be worn over the anterior portion of the eye ball (on the cornea).

IOL - Intraocular lens

PCIOL - Posterior chamber intraocular lens

ACIOL - Anterior chamber intraocular lens

Special investigations

1. Tonometry:

The introaocular pressure can be determined accurately with instruments known as tonometers.

  • Indentation tonometer - Schiotz tonometer is quite popular.
  • Applanation - Goldmann tonometer.

2. Slit lamp examination

It is essential for detailed examination of the eye. Uses high magnification to view external and internal structures of the eye.

3. Gonioscopy

To examine the angle of the anterior chamber. Gonioscopy is very useful in diagnosis and management of various glaucomas.

4. Ultrasonography

Uses sound waves to examine posterior segment of the eyeball (such as retinal detacement) when visual exploration is impossible owing to presence of cataract, blood in the eye, corneal opacities.

5. CT scan: (Computer assisted tomography)

Converts x-ray pictures into digital computer codes to make high resolution video images.

6. Fluorescein angiography:

In this test a green dye (fluorescein) is injected in the arm and photographs of the fundus are taken. Retinal capillaries as small as 5 microns which could not be visualised can now be clearly seen with the help of fluorescian angiography. It is very useful in diabetic retinopathy, hypertensive retinopathy, papilloedema, central serous retinopathy.

Dark room procedures

These procedures are done in dark room(dim light)


This is done to estimate the refraction of the eye objectively.

Direct ophthalmoscopy

The pupil should be dilated. The direct ophthalmoscope is used to examine the fundus (optic disc, vessles and macula)

Indirect ophthalmoscopy

The pupil may be dilated. Binocular indirect ophthalmoscope is worn on the examiner's head. The fundus is examined by throwing the light into the patient's eye. In this examination the periphery of the retina can be seen.


Amsler grid

A chart with horizontal and vertical lines for testing the central field of vision for scotomas and detecting macular distortion.

Cover test

A test used to detect strabismus ; when the fixating eye is occluded, the eye that is not in proper alignment must make a motion to pick up the target.

Ishihara test

A test for defects in recognising colours, based on the tracing of numbers or patterns in a series of multicolored charts or plates.

Eye lids


Is a circumscribed, acute inflammation at the edge of the lid.


Is a chronic granulomatous enlargement of one of the meibomian glands.


Is a condition in which there are involuntary and forcible eyelid closures.


Is an inversion of a varying number of eye lashes so that they rub against the conjunctiva or cornea.


It is a rolling out of the margin of the lid.


Is a cicatricial attachment between the conjunctiva of the lid and the eye ball.


This is the condition of incomplete closure of the palpebral aperture when an attempt is made to shut the eyes.


Drooping of eyelid.


Is an inflammation of conjunctiva characterized by redness of the eye and conjunctival discharges.

Ophthalmia neonatorum

It is an acute purulent conjunctivitis occurring in new born.


It is a chronic follicular keratoconjunctivitis of infectious origin. It is an important cause of blindness.

Phlyctenular keratoconjunctivitis

It is an allergic condition caused by endogenous bacterial protein, which in most cases is tuberculous.

Bitot's spots

Small triangular silvery white patches on the outer and inner side of the cornea, covered by a material resembling dried foam which is not wetted by tears. Caused by vitamin A deficency.


The above given medical terms are to be learned by the OAs and used often among colleagues and while talking to the patients. The medical terms should be used but the appropriate explanations should be given to the patient. It is very important for them to learn the spelling and write the terms without spelling mistakes.

Student exercise

Fill in the blanks

  1. Lacrimation means ___________ production due to reflex sensory stimulation.
  2. _________ is a structure at the junction of cornea and conjunctiva.
  3. _________ is a jelly like substance behind the lens and in front of retina.
  4. Cycloplegic drug often is used in __________ which temporarily places the ciliary muscle at rest and dilates the pupil.
  5. _________ examination is essential for detailed examination of the eye.