COT Cheat Sheet 2026

The 30 highest-yield COT facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Normal intraocular pressure (IOP) in adults typically ranges from: → 10–21 mmHg
2. What is the unit used to measure prismatic effect in spectacle lenses? → Prism diopter (Δ)
3. A patient with limited English proficiency arrives for a glaucoma evaluation. What is the BEST approach to ensure informed consent? → Use a qualified medical interpreter
4. A patient with nystagmus is scheduled for fundus photography. Which technique best compensates for uncontrolled eye movement? → Use a shorter flash duration
5. When reading the lensmeter, a technician finds the sphere power but the mires cannot be focused to a single clear line simultaneously. What does this indicate? → The lens has cylinder (astigmatic power)
6. In OCT imaging, 'shadow artifact' beneath a retinal vessel is caused by: → Absorption and scattering of the OCT beam by blood blocking deeper signal
7. Which one of the following is NOT a technique for nucleus removal in phacoemulsification? → Cut and paste technique
8. A patient's manifest refraction is −3.00 +1.50 ×090. What is the spherical equivalent? → −2.25 D
9. In fluorescein angiography, 'window defect' hyperfluorescence is caused by: → Loss of RPE blocking pigment revealing background choroidal fluorescence
10. A patient's refraction is plano +2.00 ×045. This represents what type of astigmatism? → Simple hyperopic astigmatism
11. Proper hand hygiene in the ophthalmic clinic should occur: → Before and after every patient contact
12. When is B-scan ultrasonography preferred over A-scan for preoperative assessment? → When media opacities prevent visualization of posterior segment structures
13. The recommended patient position for obtaining a reliable and reproducible Goldmann visual field test during documentation is: → Upright with chin and forehead resting firmly in the bowl rest
14. Which photoreceptor type is primarily responsible for color vision and functions best in photopic (bright light) conditions? → Cones
15. The Amsler grid is primarily used to detect defects in which area of the visual field? → Central 20 degrees of vision, particularly the macula
16. A basic telescopic system used for distance low vision consists of which optical components? → An objective lens and an ocular (eyepiece) lens
17. In manual keratometry, irregular mire images (distorted or blurred rings) most commonly indicate: → Corneal irregularity such as keratoconus or scarring
18. In a patient with a dense posterior subcapsular cataract, the BEST biometry method is: → Immersion A-scan
19. The refractive index assumed by most manual keratometers when converting radius of curvature to diopters is approximately: → 1.3375
20. A cotton-wool spot on fundus photography corresponds pathologically to: → Focal nerve fiber layer infarction
21. When prescribing a telescope for a patient with low vision, the primary trade-off compared to a higher-magnification telescope is: → Reduced field of view
22. The Hirschberg corneal light reflex test estimates approximately how many prism diopters of deviation per millimeter of decentration? → 22 PD per mm
23. What does the 'teach-back' method involve in patient education? → Asking the patient to explain the information back in their own words
24. Which contact lens parameter describes the curvature of the back surface of the lens and determines how it fits on the cornea? → Base curve radius
25. A patient using brimonidine eye drops should be monitored for which systemic side effect, especially in pediatric patients? → CNS depression and bradycardia
26. A pterygium is BEST described as: → A fibrovascular growth of conjunctival tissue that invades and grows across the cornea
27. During keratometry, what does the technician measure when aligning the plus (+) and minus (−) mires? → The radius of curvature of the anterior cornea in two principal meridians
28. A patient's spectacle prescription is –14.00 D measured at a vertex distance of 14 mm. Which contact lens power most accurately corrects this patient? → –11.75 D
29. When obtaining a patient's ocular history, asking about prior LASIK or refractive surgery is important primarily because it affects: → IOP measurements and IOL power calculations
30. Which surface of a spectacle lens does the lensmeter measure when the lens rests against the lens stop? → Back vertex power