ABO Advanced cheat sheet

Snellen acuity fraction: VA = test distance / letter size distance; 20/40 means a letter subtends 5 arcmin at 40 ft but is read at 20 ft.

LogMAR = log10(Snellen denominator/20); each 0.1 logMAR step equals one line, and 0.0 logMAR equals 20/20.

Spherical equivalent = sphere + (cylinder/2); used to estimate the power of a thin lens equivalent to a toric prescription.

Tear film breakup time under 10 seconds by fluorescein instillation supports a diagnosis of evaporative dry eye.

Goldmann applanation tonometry assumes a central corneal thickness of 545 microns; thinner corneas underestimate and thicker corneas overestimate IOP.

Cup-to-disc ratio progression, neuroretinal rim thinning, and disc hemorrhage are structural markers of glaucomatous optic neuropathy.

Amsler grid testing screens for macular disease; metamorphopsia suggests macular edema or epiretinal membrane.

Direct ophthalmoscopy gives roughly 15x magnification in an emmetropic eye and an upright, unreversed virtual image.

In keratoconus, inferior steepening, skewed radial axes, and asymmetric bowtie patterns appear on corneal topography.

Informed consent requires disclosure of material risks, alternatives, and the patient's right to refuse; documentation should record the discussion.

The Health Insurance Portability and Accountability Act governs protected health information; minimum necessary disclosure is the default standard.

Continuing education requirements vary by state licensure board; license renewal cycles are typically every 2 years with a set number of CE hours.

Clinical records should be legible, dated, authenticated, and retained per state statute, often a minimum of 7 to 10 years after the last encounter.

Evidence-based practice integrates best available research, clinician expertise, and patient values and preferences.

A sentinel event review uses root cause analysis to identify system failures rather than individual blame.

Scope of practice for optometrists is defined by state law and determines authority for topical or oral medications, injections, and laser procedures.

Peer review and morbidity and mortality conferences are structured quality-improvement activities that identify care gaps.

Normal adult intraocular pressure ranges from about 10 to 21 mmHg; IOP is a risk factor, not a diagnostic criterion for glaucoma.

The AC/A ratio is the change in accommodative convergence per diopter of accommodation; a normal value is approximately 4:1 to 6:1.

Cover test and alternate cover test distinguish tropia from phoria; the alternate cover test breaks fusion to reveal the total deviation.

Von Graefe phoria technique uses a dissociating prism and a measuring prism to quantify the deviation at distance and near.

In anisometropia, the difference in refractive error between eyes can produce aniseikonia and amblyopia in children.

Pinhole acuity improvement indicates a refractive cause of reduced vision, whereas no improvement suggests a pathology.

Stereopsis of 40 arcseconds on the Randot test indicates fine binocular depth perception.

Amsler grid testing screens for macular disease; metamorphopsia suggests macular edema or epiretinal membrane.

Direct ophthalmoscopy gives roughly 15x magnification in an emmetropic eye and an upright, unreversed virtual image.

Informed consent requires disclosure of material risks, alternatives, and the patient's right to refuse; documentation should record the discussion.

The Health Insurance Portability and Accountability Act governs protected health information; minimum necessary disclosure is the default standard.

Continuing education requirements vary by state licensure board; license renewal cycles are typically every 2 years with a set number of CE hours.

Clinical records should be legible, dated, authenticated, and retained per state statute, often a minimum of 7 to 10 years after the last encounter.

Evidence-based practice integrates best available research, clinician expertise, and patient values and preferences.

A sentinel event review uses root cause analysis to identify system failures rather than individual blame.

Scope of practice for optometrists is defined by state law and determines authority for topical or oral medications, injections, and laser procedures.

Peer review and morbidity and mortality conferences are structured quality-improvement activities that identify care gaps.