Kuwait MOH Optometrist flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Corneal deturgescence

The endothelial Na+/K+ ATPase pump actively removes stromal fluid, keeping the cornea relatively dehydrated and transparent; failure causes oedema and loss of clarity.

Neural crest origin

Corneal stroma and endothelium, sclera, trabecular meshwork and ciliary muscle derive from neural crest cells, while lens and corneal epithelium come from surface ectoderm.

Tear film mucin layer

Secreted by conjunctival goblet cells, it converts the hydrophobic epithelial surface to hydrophilic, allowing the aqueous layer to spread evenly over the cornea.

Aqueous outflow pathway

Aqueous passes from the anterior chamber through trabecular meshwork into Schlemm canal, then collector channels and episcleral veins; this conventional route carries most outflow.

Reduced vergence

L = n/l, where n is refractive index and l is distance in metres; used to calculate image position through a medium rather than air.

Vertex distance effect

Moving a lens away from the eye changes its effective power; the conversion is Fnew = F/(1 − dF), important for powers above about 5 dioptres.

Prentice's rule

Prism dioptres induced equal decentration in centimetres multiplied by lens power in dioptres; used to check prism tolerance and optical centre placement.

Jackson cross-cylinder

A lens with equal and opposite cylinder powers at right angles; rotated to refine cylinder axis and power during subjective refraction.

Clinically significant macular oedema

Retinal thickening within 500 micrometres of the fovea, hard exudates with adjacent thickening, or a lesion at least one disc area within one disc diameter of the fovea.

Keratoconus signs

Inferior corneal steepening, Fleischer ring, Vogt striae and Munson sign; corneal tomography confirms ectasia before slit-lamp signs appear.

Anterior uveitis signs

Cells and flare in the anterior chamber, ciliary flush, photophobia and miosis; associations include HLA-B27 disease and sarcoidosis.

Dk/t

Oxygen transmissibility of a contact lens, equal to permeability divided by thickness; higher values reduce hypoxic complications, especially in extended wear.

Tear lens effect

The fluid layer between a rigid lens and cornea acts as a lens; a steep fit adds plus power and a flat fit adds minus power to the system.

CLARE

Contact lens acute red eye: a sterile corneal infiltrative response to hypoxia or lens deposits, presenting with redness and irritation, usually resolving after lens removal.

Hirschberg test

Corneal light reflex position estimates deviation; about one millimetre of displacement equals roughly seven degrees or fifteen prism dioptres.

AC/A ratio

Accommodative convergence per dioptre of accommodation; normal is about 4 to 6 prism dioptres per dioptre, higher in convergence excess.

Amblyopia management

Correct refractive error first, then occlude or penalise the better eye during the critical period; adherence and follow-up determine outcome.

Worth 4-dot test

A red-green dissociation test assessing fusion, suppression and diplopia; four lights indicate fusion, two or three indicate suppression.

Seidel test

Fluorescein applied to the cornea shows a dark stream against green fluorescence where aqueous leaks, indicating full-thickness perforation.

Alkali injury

Alkali agents penetrate deeper than acids, causing liquefactive necrosis; immediate copious irrigation for at least thirty minutes is sight-saving.

Cycloplegic duration

Tropicamide lasts four to six hours, cyclopentolate about twenty-four hours, and atropine up to two weeks; choose according to examination needs.

Steroid response

Some patients develop raised intraocular pressure with topical steroids; monitor pressure and taper, especially in known steroid responders.

Humphrey reliability indices

Fixation losses, false positives and false negatives indicate test validity; high false positives shorten and flatten the field and must be interpreted cautiously.

Shaffer grading

Gonioscopic angle grading from zero to four; grades zero and one indicate narrow or closed angles with risk of angle closure.

Central corneal thickness

Pachymetry influences Goldmann applanation readings; thinner corneas tend to underestimate pressure and are an independent glaucoma risk factor.

OCT angiography

Dye-free imaging of retinal and choroidal blood flow; useful for choroidal neovascularisation and ischaemia, but motion and projection artefacts must be excluded.

Valid consent

Requires patient capacity, sufficient information about risks and alternatives, and voluntary agreement; the discussion should be documented in the record.

Confidentiality exceptions

Disclosure without consent may occur when required by law, to protect public safety, or to prevent serious harm; record the legal basis.

Screening test criteria

A good screening test has high sensitivity and acceptable specificity; positive results require confirmatory diagnostic testing before treatment.

Hand hygiene choice

Alcohol-based rub is used for routine decontamination; soap and water is required when hands are visibly soiled or after contact with spore-forming organisms.

Tonometer disinfection

Applanation prisms must be cleaned with an approved agent or fitted with a disposable tip between patients, following the manufacturer's contact time.

Duty of urgent referral

Same-day referral is required for retinal detachment, acute angle closure, chemical injury and sudden vision loss; delay risks permanent visual loss.

Prescription requirements

A valid prescription includes patient identifiers, drug name and strength, directions, quantity, date, prescriber signature and registration number.