COT Contact Lens Principles 5

Question 1

Which term describes the phenomenon where a soft contact lens tightens on the eye after extended wear, reducing movement?

Accepted Answer

Lens binding (tight lens syndrome)

Answer

Lens binding occurs when mucus accumulates under the lens and adheres to the cornea, causing the lens to become immobile — particularly after extended or overnight wear.

Question 2

A patient wearing daily soft lenses develops a red eye immediately after insertion each morning. The most likely cause is:

Accepted Answer

Toxicity or hypersensitivity to the lens packaging solution or preservative

Answer

Immediate-onset redness upon insertion of daily disposable lenses suggests a reaction to the packaging solution (e.g., phosphate buffer) rather than a chronic deposit issue.

Question 3

Which keratometry reading relationship is used as a starting guide when selecting an initial RGP base curve?

Accepted Answer

Select a base curve 0.25–0.50 D steeper than the flattest K (align or slightly steep)

Answer

A common starting guideline is to fit the RGP base curve on K (aligned) or slightly steeper than the flattest keratometry reading to achieve an aligned fluorescein pattern.

Question 4

What does a 'plus carrier' lenticular design in a rigid contact lens provide?

Accepted Answer

A thicker peripheral zone to improve lid interaction and superior positioning

Answer

A plus carrier lenticular edge is thicker at the periphery, encouraging the upper lid to ride over and center the lens in a lid-attachment fit.

Question 5

Corneal neovascularization (pannus) associated with contact lens wear is primarily caused by:

Accepted Answer

Chronic hypoxia stimulating new blood vessel growth into the cornea

Answer

Prolonged corneal hypoxia triggers angiogenic factors (VEGF) that stimulate limbal blood vessel growth into the normally avascular cornea.

COT - Certified Ophthalmic Technician Practice Test

COT - Certified Ophthalmic Technician Practice Test

COT Contact Lens Principles 5