COMT flashcards
COMT · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Corneal layers in order
- Epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The endothelium does not regenerate; it pumps fluid out of the stroma to maintain corneal clarity and thickness.
- Aqueous humor outflow pathway
- Produced by the ciliary epithelium, aqueous flows from the posterior chamber through the pupil into the anterior chamber and exits mainly through the trabecular meshwork into Schlemm's canal.
- Extraocular muscle innervation
- Lateral rectus is supplied by CN VI and superior oblique by CN IV; the superior, inferior, and medial rectus muscles plus the inferior oblique are all supplied by CN III.
- Cup-to-disc ratio significance
- Cupping greater than 0.6, asymmetry over 0.2 between fellow eyes, or progressive enlargement with disc hemorrhage or notching suggests glaucomatous optic neuropathy and warrants referral.
- Rods versus cones distribution
- About 120 million rods mediate dim-light and peripheral vision, while roughly 6 million cones concentrate at the fovea and provide color vision and high visual acuity.
- Vertex distance conversion formula
- Fc = Fs divided by (1 minus d times Fs), where d is vertex distance in meters. The conversion becomes clinically significant when spectacle power exceeds about plus or minus 4.00 diopters.
- Snell's law
- n1 sin theta1 equals n2 sin theta2, giving the angle at which light bends when crossing an interface between two media with different refractive indices.
- Keratometric index conversion
- Dioptric power equals (1.3375 minus 1) divided by the corneal radius in meters. The 1.3375 keratometric index is used because keratometry measures only the anterior corneal surface.
- LARS rule for toric lenses
- If a toric soft lens rotates to the clinician's left, add to the cylinder axis; if it rotates right, subtract. The rule compensates for lens rotation on the eye.
- Prism diopter definition
- One prism diopter deviates a ray of light by 1 centimeter at a distance of 1 meter. Prism power is used to quantify and correct strabismic deviations.
- Goldmann applanation normal range
- Normal intraocular pressure by Goldmann applanation is approximately 10 to 21 mmHg. Thick corneas overestimate and thin corneas underestimate the true intraocular pressure.
- Humphrey 24-2 test points
- The 24-2 threshold program tests 54 points spaced 6 degrees apart within the central 24 degrees and is the standard visual field test for glaucoma.
- Mean deviation field index
- Mean deviation averages the difference between the patient's measured sensitivity and age-matched normal values; a large negative value reflects widespread depression such as cataract or advanced glaucoma.
- Pattern standard deviation index
- Pattern standard deviation quantifies localized irregular field loss after removing overall depression. It rises in focal defects such as glaucoma and is flagged when the probability value is 5 percent or less.
- A-scan versus B-scan
- A-scan is a one-dimensional amplitude display used to measure axial length for intraocular lens calculation; B-scan is a two-dimensional cross-sectional image used to evaluate the posterior segment.
- Tropicamide duration of action
- Tropicamide is a short-acting anticholinergic mydriatic and cycloplegic with effects lasting about 4 to 6 hours, commonly used for routine dilated fundus examination.
- Atropine cycloplegia duration
- Atropine 1% produces cycloplegia lasting 7 to 14 days and is used for cycloplegic refraction in children, particularly those with accommodative esotropia.
- Prostaglandin analog side effects
- Latanoprost lowers intraocular pressure by increasing uveoscleral outflow and can cause iris darkening, eyelash lengthening, and periorbital skin pigmentation.
- Timolol contraindications
- Timolol is a topical beta-blocker that reduces aqueous production but may cause bronchospasm and bradycardia, so it is avoided in asthma, COPD, and heart block.
- Autoclave sterilization parameters
- Standard steam autoclave sterilization uses 121 degrees Celsius at 15 psi for 15 to 20 minutes, or a 132 degrees Celsius flash cycle for a shorter exposure time.
- Snellen 20/20 letter size
- At 6 meters (20 feet), a 20/20 letter subtends a total of 5 arc minutes, and each stroke of the letter subtends 1 arc minute.
- Corneal suture material
- 10-0 nylon is the standard suture for corneal and cataract incisions because it is fine, strong, and minimally reactive; it is often removed after the wound stabilizes.
- Povidone-iodine surgical prep
- Dilute povidone-iodine 5% is applied to the conjunctival cul-de-sac and periocular skin before intraocular surgery to reduce the risk of postoperative endophthalmitis.
- Surgical time-out purpose
- Immediately before incision the surgical team confirms patient identity, the correct eye with the site marked, the procedure, consent, and antibiotic prophylaxis to prevent wrong-site surgery.
- Pinhole test interpretation
- If visual acuity improves through a pinhole, reduced vision is most likely from uncorrected refractive error; no improvement suggests media opacity or retinal or neural disease.
- Punctal occlusion after drops
- Pressing over the lacrimal sac for 1 to 2 minutes after instilling drops reduces drainage into the nasolacrimal duct and limits systemic absorption and side effects.
- Chemical eye injury first aid
- Immediately irrigate the eye with saline or lactated Ringer's solution for at least 15 to 30 minutes, checking the pH until neutral before any other assessment.
- Instilling eye drops technique
- Retract the lower lid to expose the cul-de-sac, instil a single drop without touching the tip to the eye, then release the lid and let the patient close gently.
- HIPAA release of records
- Protected health information may be disclosed only with a signed, dated patient authorization naming the recipient and purpose, unless an exception such as treatment, payment, or health care operations applies.
- CPT modifier 25
- Modifier 25 is added to an evaluation and management code when a separately identifiable E/M service is provided on the same day as a procedure.
- Modifiers LT and RT
- LT and RT are claim modifiers identifying the left or right eye or side, clarifying which structure was examined or treated on that date of service.
- OSHA bloodborne pathogens standard
- The OSHA bloodborne pathogens standard requires employers to offer hepatitis B vaccination, provide personal protective equipment, maintain an exposure control plan, and train occupationally exposed employees.