OPTO Flashcards
Aberration
Distortions, related to astigmatism , that cause the inability of light rays entering the eye to converge (come together) to a single focus point on the retina.
2 Categories:
Higher-order
Lower-order.
Ablation
Surgical removal of tissue, typically using a cool beam laser
Accommodation
The automatic adjustment of optical power by the eye in order to maintain a clear image (focus) as objects are moved closer
Altitudinal Visual Field Defects
Upper or lower half of the VF is selectively affected
- Creates a horizontal line across the VF - “respecting the horizontal meridian”
- Altitudinal defects occur in retinal vascular disease, glaucoma, and other disorders that affect the eye itself.
Amblyopia
Dullness or obscurity of sight for no apparent organic reason, not correctable w/ specs or sx.
- Lazy Eye - one eye becomes dependent on the other eye to focus, usually dev’t in early childhood. Often associated with strabismus.
AMD
Disease that damages the macula, the central part of the retina, leading to a loss of central vision and leaving only the peripheral or lateral vision intact.
Ametropia
Refers to the broad condition of having some form of refractive error present in your eye
- ie: Myopia, Hyperopia, Astigmatism
Angle (Drainage Angle)
Drainage area of the eye formed between the cornea and the iris
- Named for its angular shape
Anisometropia
Eye condition: have unequal refractive power
Anterior Chamber
Space between the cornea and the crystalline lens, contains aqueous humor
Antimetabolite
Drugs that retards cell division and slows down healing
- In Glaucoma sx: used to prevent the drainage site from failing because of scarring.
Antioxidants
Micronutrients that destroy or neutralize free radicals - molecules that stimulate abnormal cellular reproduction (cancer) and cellular destruction (aging).
Anti-VEGF drugs
Drugs that block the action of Vascular Endothelial Growth Factor
- Effective in the treatment of Choroidal Neovascularisation
Aphakia
Absence of the lens of the eye
Aqueous / Aqueous Humor
Transparent fluid occupying the anterior chamber and maintains eye pressure
Argon laser
Device used to treat glaucoma (usually open angle) and diabetic retinopathy using a thermal beam
Asthenopia
Eyestrain
- Subjective symptoms of ocular fatigue, discomfort, lacrimation, and headaches arising from the use of eyes
Astigmatic Keratotomy
A modified form of Radial Keratotomy (RK)
Astigmatism
Structural defects of the eye in which the light rays from a viewed object do not meet in a single focal point, resulting in blurred images being sent to the brain
Autosomal recessive
An inheritance pattern in which a person must inherit two copies of an abnormal gene (one from each parent) in order to develop the disease. If two individuals each carry one copy of an abnormal gene, then each child born to these two parents will have a 25% chance of receiving 2 copies of the abnormal gene and as a result, inherit the disease. Cystic fibrosis is an example of an autosomal recessive disease
Binocular Vision
Focusing and fusing of the separate images seen by each eye into one single binocular image
Biologic Therapeutic Agent
A group of genetically engineered antibodies which target specific molecules involved in the immune system or the system which regulates inflammation and block their action. Anti-VEGF drugs belong to this group.
Blind Spot
Sightless area within the visual field of a normal eye, where the optic disc attaches the optic nerve to the eye. Caused by absence of light sensitive photoreceptors where the optic nerve enters the eye
Cataract
Opacification/Clouding of the crystalline lens.
- Types: traumatic, congenital, age-related
Cecocentral Scotomas
These are visual field defects that extend from the central vision to the natural blind spot. This type of field defect usually represents an insult to the cluster of retinal ganglion cells called the papillomacular bundle
Central Vision
An eye’s best vision; used for reading and discriminating fine detail and color
Choroid
The pigmented layer of the eye between the retina and the sclera
- Contains a rich network of blood vessels
Choroidal Neovascular Membrane
Wet Macular Degeneration - complication of ARMD
- Network of blood vessels which originates from the choroid layer which comes to lie just under the retina, resulting in leakage of fluid or bleeding into the retina
Ciliary Body
A pigmented part of the eye, lying just behind the iris. One of its functions is to produce aqueous
Conjunctivochalasis
A redundant folds in the conjunctiva typically located between the globe and the lower eyelid. Loose bulbar conjunctiva that may become pinched between the lids and cause tearing and inflammation. Frequently age-related. Usually found along the lower lid margin. It interferes with the normal distribution of tears causing dry eye and epiphora
Convergence
Reflex that enables the eyes to focus on a single point in near vision
Cornea
Front window of the eye
- Transparent front part of the globe shaped like a slightly domed cap, covering the iris, pupil, and anterior chamber and provides most of an eye’s optical power.
Crystalline Lens
Transparent biconvex lens located behind the pupil; refracts light to focus images on the retina
- Natural lens inside of the eye
Cupping (Disk Cupping)
An enlargement of the cup or central depression in the optic nerve head
- Visible with an ophthalmoscope
- If accompanied by a notch or a small spot of bleeding is a sign of glaucoma.
- Cupping is a clinical sign that indicates that a large number of nerve fibers in the optic nerve have been lost
Cycloplegic
A substance which paralyses the ciliary muscle. It is usually necessary to use this to obtain an accurate measurement of refractive error in younger children
Descemet’s Membrane
A layer of the cornea which lies just forward of the endothelium
Deuteranopia / Deuteranopic
Complete color deficiency affecting the ability to see the color green
- 3 possible color vision deficits:
Red (protan)
Green (deutan)
Blue (tritan)
- The suffixes -omaly and -opia indicate partial and complete color vision deficits, respectively. Therefore, a person who has deuteranopia has a complete green color deficit.
Digital Surfacing
Precise surface cutting using single point turning; cutting height is controlled at all points on the lens
Dyschromotopsia
Colour blindness
- Heritable vision deficits:
Red (protan) - x-linked
Green (deutan) - x-linked
Blue (tritan) - autosomal recessive
- Either partial (-omaly) or complete
(-opia).
Electroretinogram (ERG)
A test that measures the electrical activity of the retina when exposed to flashes of light of varying intensity. Abnormalities in the electroretinogram typically occur in conditions that affect the photoreceptor cells (e.g. retinitis pigmentosa).
Emmetropia
Emmetropia is a term that refers to the condition of having “normal” 20/20 vision, with eyes free of refractive errors
- Sometimes called ‘normal 20/20 vision’ - images at 20ft focus sharply on the retina
Endophthalmitis
Infection which involves the internal structures of the eye. It usually poses a serious threat to the visual function of the eye
Endothelium
The layer of the cornea closest to the anterior chamber. It is a single layer of cells which does not regenerate after birth. Its function is to pump fluid out of the cornea. If it fails, the cornea becomes hazy (decompensates).
Epiphora
Excessive tear production or insufficient tear drainage from the eyes (usually from blockage of the lacrimal duct) causing overflow of tears onto the face.
Excimer laser
A type of laser which emits in the ultraviolet range of the spectrum. In ophthalmology, it is used for removing tissue from the cornea, particularly in refractive surgery
Fovea Centralis / Fovea
(Latin: ‘the pit/pitfall’)
- Small depression in the center of the macula region of the retina.
- Produces the sharpest focus
- High concentration of cones which aid in clear central vision
- About 1.0 mm dia. with a high concentration of cone photoreceptors
Foveal burn
A laser burn in the fovea, which can occur as an adverse event during retinal laser treatment
Foveola
The center of the fovea
- About 0.2 mm in diameter
- Only cone photoreceptors are present, very compact cones, thinner and more rod-like in appearance than cones elsewhere
- Starting at the outskirts of the fovea, however, rods gradually appear, and the absolute density of cone receptors progressively decreases.
Glaucoma
A condition, usually characterised by raised pressure in the eye which causes damage to the optic nerve resulting in defects in the field of vision. It is treated by reducing the pressure in the eye. Increase in intra-ocular pressure resulting, if left untreated, in an irreversible deterioration of the optical nerve and of the retina, as well as an alteration of the visual field, i.e. a reduction in visual performance, often accompanied by headaches and aching eyes. A disease of the eye characterized by increased intraocular pressure. A common cause of preventable vision loss. May be treated by prescription drugs or surgery.
Glaucoma (Normal/Low Tension Glau)
Glaucoma in which the intraocular pressure is normal but there is progressive optic nerve damage and visual field loss.
Goldmann Visual Field
Tangent screen or Goldmann field exam.
The object is usually a pin or bead on the end of a black stick that is moved by the examiner. This exam creates a map of your central 30 degrees of vision. This exam is usually used to detect brain or nerve (neurologic) problems.
Humphrey Visual Field
Measures the entire area of peripheral vision that can be seen while the eye is focused on a central point.
Hyperopia
Far-sightedness, an eye that is too short and/or insufficiently powered. The image forms behind the retina, which explains why the hyperopic subject has better eyesight in far vision than in near vision.. Corrected with plus (convex) lenses.
Incomplete Penetrance
The concept that even though several members of a family or population may have the same DNA mutation, not everyone with that mutation will have or develop the disease. This is in contrast to variable expressivity which means that people with the same disease have varying disease severity. Penetrance, in contrast, is more of a yes/no question. Does or does not the person have the disease.
Intraocular Pressure
Fluid pressure exerted inside the eyeball (ocular globe), which keeps the wall taut
Iris
Pigmented tissue lying behind the cornea that gives color to the eye
- Acts as a diaphragm that contracts according to the intensity of light
- Controls light by contracting and constricting the opening (pupil).
Lens Capsule
The eye’s lens consists of tightly packed layers of transparent protein fibres contained within an elastic capsule. During cataract surgery, the layers of lens fibres are removed, but the posterior part of the lens capsule and its supporting zonular fibres are retained to act as a support for the lens implant.
Lenticulation
The process of thinning the edges of a minus lens or centers of plus lenses using a carrier shape or change of curvature. It involves specifying an area of the lens as the ‘visual area’, which is the part of the lens the patient is intended to actually look through. This ‘visual area’ is also referred to as a ‘bowl’, and can be as small as 30mm. The balance of the lens has edges thinned in minus lenses and centers thinned in plus.
Limbus
The region where the cornea and the sclera meet.
Low Vision
When you’re either legally blind (you have a best corrected visual acuity of less than 20/200 or tunnel vision) or have visual acuity between 20/70 and 20/200, despite the use of glasses or contacts
