NBEO TMOD flashcards

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

Positive predictive value

The proportion of positive test results that are true positives. It rises with disease prevalence, so the same test performs better in high-prevalence populations such as referral clinics than in general screening.

Negative predictive value

The proportion of negative test results that are true negatives. It is highest when disease prevalence is low, which is why a negative screening test in a healthy population is reassuring.

Sensitivity definition

The ability of a test to identify people who have the disease, calculated as true positives divided by true positives plus false negatives. High sensitivity means few cases are missed.

Specificity definition

The ability of a test to identify people without the disease, calculated as true negatives divided by true negatives plus false positives. High specificity means few healthy people are falsely flagged.

Likelihood ratio positive

Sensitivity divided by one minus specificity. A value above ten substantially raises post-test probability, while values between two and five produce only modest changes.

Pretest odds calculation

Convert probability to odds by dividing probability by one minus probability. Multiply pretest odds by the likelihood ratio to obtain post-test odds, then convert back to probability.

SnNout rule

A highly sensitive test with a negative result effectively rules out disease. Sensitivity near one hundred percent means false negatives are rare, so a negative result is reassuring.

SpPin rule

A highly specific test with a positive result effectively rules in disease. Specificity near one hundred percent means false positives are rare, so a positive result strongly supports the diagnosis.

Red flag: sudden vision loss

Painless sudden monocular vision loss suggests vascular occlusion or retinal detachment and requires urgent assessment. Painful loss with a red eye suggests acute angle closure or keratitis.

Afferent pupillary defect

A relative afferent pupillary defect detected with the swinging flashlight test indicates asymmetric optic nerve or extensive retinal dysfunction and is a red flag requiring prompt neuro-ophthalmic evaluation.

Monocular versus binocular diplopia

Monocular diplopia persists when one eye is covered and usually reflects optical causes such as cataract or irregular astigmatism. Binocular diplopia resolves with either eye covered and implies ocular misalignment.

Chemical eye injury triage

Copious irrigation begins immediately, before history taking or slit lamp examination. Alkali injuries penetrate more deeply than acids and require urgent ophthalmology referral after irrigation.

Test threshold concept

A test is ordered only when its result could cross the treatment threshold and change management. Tests that leave the plan unchanged add cost and risk without clinical benefit.

Pattern recognition in diagnosis

Onset, laterality, pain, and duration each narrow the differential. Sudden versus gradual and painful versus painless create four broad categories that guide the initial examination and testing strategy.

Concordant findings rule

Independent findings that agree, such as a thin neuroretinal rim plus a matching field defect, raise diagnostic confidence far more than repeated nonspecific signs such as redness or tearing alone.

Ocular emergency time frames

Chemical burns, acute angle closure, giant cell arteritis, retinal artery occlusion, and endophthalmitis require same-day management. Delay in any of these measurably worsens final visual outcome.

Intraocular pressure interpretation

Pressure is a modifiable risk factor rather than a diagnosis. Glaucomatous damage can occur at pressures of twenty-one or below, and elevated pressure alone does not confirm glaucoma.

Glaucomatous field defect features

Defects respecting the horizontal midline, reproducible on repeat testing, and corresponding to disc structure suggest glaucoma. Single-point or cloverleaf patterns often reflect testing artifact or unreliable performance.

Visual field reliability indices

Fixation losses, false positives, and false negatives indicate test validity. High false-positive rates produce artificially bright fields, and high fixation losses can create spurious peripheral defects, so unreliable fields should be repeated.

OCT normative comparison

Retinal nerve fiber layer thickness is compared with age-matched norms and the patient's own baseline. Progressive thinning over serial scans supports progression even when pressure appears controlled.

Target intraocular pressure

The pressure range expected to halt further glaucomatous damage, set from baseline pressure, damage severity, life expectancy, and risk factors, then adjusted if progression occurs.

Occludable angle management

Narrow or occludable angles identified on gonioscopy warrant prophylactic laser peripheral iridotomy, especially with risk factors such as hyperopia, shallow anterior chamber, or family history of angle closure.

Diabetic retinopathy follow-up

Mild nonproliferative retinopathy may be monitored every six to twelve months. Severe nonproliferative or any proliferative disease needs referral for panretinal photocoagulation or anti-VEGF therapy.

Diabetic macular edema rule

Macular edema is treated with anti-VEGF therapy regardless of retinopathy grade. Its presence changes the plan from observation to active treatment and often requires more frequent follow-up.

Exudative AMD conversion

New subretinal fluid, hemorrhage, or distortion on Amsler grid indicates conversion to exudative disease. Anti-VEGF injection is time-sensitive because delay reduces final visual acuity.

Corneal ulcer management

Bacterial ulcers are treated with frequent topical antibiotics and daily review. Fungal ulcers respond slowly to antifungal agents, and any ulcer with hypopyon or worsening needs urgent ophthalmology input.

Uveitis systemic workup

Anterior uveitis with joint, skin, or bowel symptoms suggests an associated systemic disease and warrants directed workup rather than isolated topical treatment alone.

Prolonged topical steroid risks

Long-term topical corticosteroid use requires monitoring for cataract formation, steroid-induced pressure elevation, and secondary infection, with pressure checked at each follow-up visit.

Referral documentation standard

The referral note states the reason, the level of urgency, and the requested follow-up interval so the receiving clinician can triage and the patient's care is not delayed.

Structural-functional concordance

Glaucoma progression is confirmed when structural change on OCT and functional change on visual field agree. Discordant or isolated findings usually warrant repeat testing before altering therapy.

Amsler grid interpretation

Metamorphopsia or new scotoma on the Amsler grid suggests macular disease, particularly exudative age-related macular degeneration, and prompts urgent dilated examination and OCT imaging.