optician provides answers for CET Module C4823e (April 30)1 What is the measured flow rate of the aqueous? (A) 1 microlitre per minute; (B) 2 to 3 microlitres per minute; (C) 5 microlitres per minute; (D) 8 microlitres per minute.
The correct answer is B. Aqueous flow rates vary between 2 to 3 microlitres per minute.
2 In what way does the flow rate of aqueous change between the ages of 10 and 80 years old? (A) 25 per cent increase in flow; (B) 25 per cent decrease in flow; (C) No change; (D) No change until the lens significantly hinders outflow in the seventh and eighth decades.
The correct answer is B. Work by Brubaker showed as much as a 25 per cent decrease in aqueous flow rates from the age of 10 to 80 years of age.
3 Which of the following might represent the anterior chamber depth of an emmetropic 20-year-old adult? (A) 11.3mm; (B) 3 microns; (C) 0.1mm; (D) 3.2 mm.
The correct answer is D. Chamber depth varies from around 2.9mm to 3.8mm, depending on the age and refractive status of the patient. The older or more hypermetropic the patient, the shallower the anterior chambr depth.
4 Which of the following statements concerning the uveo-scleral drainage pathway is true? (A) It is promoted by pilocarpine; (B) It is the primary drainage route for aqueous in humans; (C) It operates via the ciliary muscle into the supraciliary and suprachoroidal spaces; (D) It links the canal of Schlemm with the ocular venous drainage via aqueous veins.
The correct answer is C. Aqueous may enter the loose connective tissue in front of the ciliary muscle and pass between the muscle fibres into the supraciliary and suprachoroidal spaces.
5 Which of the following proposed mechanisms for aqueous production is now widely held to be the method of aqueous production? (A) Ultrafiltration; (B) Passive diffusion; (C) Active secretion; (D) Osmosis.
The correct answer is C. Over the years there have been many theories explaining aqueous production. It is now widely recognised that the active secretion of ions across the ciliary epithelium is the primary mechanism for the formation of aqueous.
6 Which of the following ionic species is not actively secreted by the ciliary epithelium? (A) Fe+; (B) Na+; (C) Cl-; (D) HCO3-.
The correct answer is A. Several ionic species are known to be actively secreted by the ciliary epithelium, including sodium, chloride and bicarbonate but not iron.
7 If the ratio of corneal thickness to anterior chamber gap assessed by the van Herrick method is 1:0.3, what grade would be noted on the records? (A) Grade 1; (B) Grade 2; (C) Grade 3; (D) Grade 4.
The correct answer is B. Grade 2 would be appropriate where the anterior chamber gap is between a quarter and a half the thickness of the corneal section.
8 Which of the following drugs reduces intraocular pressure primarily by reducing secretion of aqueous? (A) Timolol; (B) Dorzolamide; (C) Clonidine; (D) Prostoglandin analogues.
The correct answer is B. Dorzolamide is a carbonic anhydrase inhibitor and as such is known to cause a substantial drop in aqueous secretion.
9 Which is the most anterior structure of the conventional drainage pathway when viewed by gonioscopy? (A) Canal of Schlemm; (B) Scleral spur; (C) Trabecular meshwork; (D) Schwalbe's line.
The correct answer is D. Schwalbe's line is the most anterior structure viewed when gonioscopy is carried out on an open and patent anterior chamber angle.
10 What is the main mechanism whereby pilocarpine reduces intraocular pressure? (A) Pronounced effect on ciliary muscle contraction; (B) Miosis opening up the trabecular meshwork; (C) Direct action on smooth muscle within the trabecular meshwork; (D) Encourages outflow via the uveo-scleral route.
The correct answer is A. The IOP-lowering effect of pilocarpine is now thought to be due to its more pronounced effect on ciliary muscle contraction.
11 Which receptor types predominate in the ciliary processes? (A) a1; (B) b1; (C) a2; (D) b2.
The correct answer is D. The ciliary muscle has predominantly b2 receptors.
12 Which of the following drugs reduces outflow via the uveo-scleral route? (A) Latanoprost; (B) Adrenaline; (C) Pilocarpine; (D) Travoprost.
The correct answer is C. Unlike the other three drugs, pilocarpine will actually reduce outflow via the uveoscleral route.1 What is the measured flow rate of the aqueous? (A) 1 microlitre per minute; (B) 2 to 3 microlitres per minute; (C) 5 microlitres per minute; (D) 8 microlitres per minute.
The correct answer is B. Aqueous flow rates vary between 2 to 3 microlitres per minute.
2 In what way does the flow rate of aqueous change between the ages of 10 and 80 years old? (A) 25 per cent increase in flow; (B) 25 per cent decrease in flow; (C) No change; (D) No change until the lens significantly hinders outflow in the seventh and eighth decades.
The correct answer is B. Work by Brubaker showed as much as a 25 per cent decrease in aqueous flow rates from the age of 10 to 80 years of age.
3 Which of the following might represent the anterior chamber depth of an emmetropic 20-year-old adult? (A) 11.3mm; (B) 3 microns; (C) 0.1mm; (D) 3.2 mm.
The correct answer is D. Chamber depth varies from around 2.9mm to 3.8mm, depending on the age and refractive status of the patient. The older or more hypermetropic the patient, the shallower the anterior chambr depth.
4 Which of the following statements concerning the uveo-scleral drainage pathway is true? (A) It is promoted by pilocarpine; (B) It is the primary drainage route for aqueous in humans; (C) It operates via the ciliary muscle into the supraciliary and suprachoroidal spaces; (D) It links the canal of Schlemm with the ocular venous drainage via aqueous veins.
The correct answer is C. Aqueous may enter the loose connective tissue in front of the ciliary muscle and pass between the muscle fibres into the supraciliary and suprachoroidal spaces.
5 Which of the following proposed mechanisms for aqueous production is now widely held to be the method of aqueous production? (A) Ultrafiltration; (B) Passive diffusion; (C) Active secretion; (D) Osmosis.
The correct answer is C. Over the years there have been many theories explaining aqueous production. It is now widely recognised that the active secretion of ions across the ciliary epithelium is the primary mechanism for the formation of aqueous.
6 Which of the following ionic species is not actively secreted by the ciliary epithelium? (A) Fe+; (B) Na+; (C) Cl-; (D) HCO3-.
The correct answer is A. Several ionic species are known to be actively secreted by the ciliary epithelium, including sodium, chloride and bicarbonate but not iron.
7 If the ratio of corneal thickness to anterior chamber gap assessed by the van Herrick method is 1:0.3, what grade would be noted on the records? (A) Grade 1; (B) Grade 2; (C) Grade 3; (D) Grade 4.
The correct answer is B. Grade 2 would be appropriate where the anterior chamber gap is between a quarter and a half the thickness of the corneal section.
8 Which of the following drugs reduces intraocular pressure primarily by reducing secretion of aqueous? (A) Timolol; (B) Dorzolamide; (C) Clonidine; (D) Prostoglandin analogues.
The correct answer is B. Dorzolamide is a carbonic anhydrase inhibitor and as such is known to cause a substantial drop in aqueous secretion.
9 Which is the most anterior structure of the conventional drainage pathway when viewed by gonioscopy? (A) Canal of Schlemm; (B) Scleral spur; (C) Trabecular meshwork; (D) Schwalbe's line.
The correct answer is D. Schwalbe's line is the most anterior structure viewed when gonioscopy is carried out on an open and patent anterior chamber angle.
10 What is the main mechanism whereby pilocarpine reduces intraocular pressure? (A) Pronounced effect on ciliary muscle contraction; (B) Miosis opening up the trabecular meshwork; (C) Direct action on smooth muscle within the trabecular meshwork; (D) Encourages outflow via the uveo-scleral route.
The correct answer is A. The IOP-lowering effect of pilocarpine is now thought to be due to its more pronounced effect on ciliary muscle contraction.
11 Which receptor types predominate in the ciliary processes? (A) a1; (B) b1; (C) a2; (D) b2.
The correct answer is D. The ciliary muscle has predominantly b2 receptors.
12 Which of the following drugs reduces outflow via the uveo-scleral route? (A) Latanoprost; (B) Adrenaline; (C) Pilocarpine; (D) Travoprost.
The correct answer is C. Unlike the other three drugs, pilocarpine will actually reduce outflow via the uveoscleral route.1 What is the measured flow rate of the aqueous? (A) 1 microlitre per minute; (B) 2 to 3 microlitres per minute; (C) 5 microlitres per minute; (D) 8 microlitres per minute.
The correct answer is B. Aqueous flow rates vary between 2 to 3 microlitres per minute.
2 In what way does the flow rate of aqueous change between the ages of 10 and 80 years old? (A) 25 per cent increase in flow; (B) 25 per cent decrease in flow; (C) No change; (D) No change until the lens significantly hinders outflow in the seventh and eighth decades.
The correct answer is B. Work by Brubaker showed as much as a 25 per cent decrease in aqueous flow rates from the age of 10 to 80 years of age.
3 Which of the following might represent the anterior chamber depth of an emmetropic 20-year-old adult? (A) 11.3mm; (B) 3 microns; (C) 0.1mm; (D) 3.2 mm.
The correct answer is D. Chamber depth varies from around 2.9mm to 3.8mm, depending on the age and refractive status of the patient. The older or more hypermetropic the patient, the shallower the anterior chambr depth.
4 Which of the following statements concerning the uveo-scleral drainage pathway is true? (A) It is promoted by pilocarpine; (B) It is the primary drainage route for aqueous in humans; (C) It operates via the ciliary muscle into the supraciliary and suprachoroidal spaces; (D) It links the canal of Schlemm with the ocular venous drainage via aqueous veins.
The correct answer is C. Aqueous may enter the loose connective tissue in front of the ciliary muscle and pass between the muscle fibres into the supraciliary and suprachoroidal spaces.
5 Which of the following proposed mechanisms for aqueous production is now widely held to be the method of aqueous production? (A) Ultrafiltration; (B) Passive diffusion; (C) Active secretion; (D) Osmosis.
The correct answer is C. Over the years there have been many theories explaining aqueous production. It is now widely recognised that the active secretion of ions across the ciliary epithelium is the primary mechanism for the formation of aqueous.
6 Which of the following ionic species is not actively secreted by the ciliary epithelium? (A) Fe+; (B) Na+; (C) Cl-; (D) HCO3-.
The correct answer is A. Several ionic species are known to be actively secreted by the ciliary epithelium, including sodium, chloride and bicarbonate but not iron.
7 If the ratio of corneal thickness to anterior chamber gap assessed by the van Herrick method is 1:0.3, what grade would be noted on the records? (A) Grade 1; (B) Grade 2; (C) Grade 3; (D) Grade 4.
The correct answer is B. Grade 2 would be appropriate where the anterior chamber gap is between a quarter and a half the thickness of the corneal section.
8 Which of the following drugs reduces intraocular pressure primarily by reducing secretion of aqueous? (A) Timolol; (B) Dorzolamide; (C) Clonidine; (D) Prostoglandin analogues.
The correct answer is B. Dorzolamide is a carbonic anhydrase inhibitor and as such is known to cause a substantial drop in aqueous secretion.
9 Which is the most anterior structure of the conventional drainage pathway when viewed by gonioscopy? (A) Canal of Schlemm; (B) Scleral spur; (C) Trabecular meshwork; (D) Schwalbe's line.
The correct answer is D. Schwalbe's line is the most anterior structure viewed when gonioscopy is carried out on an open and patent anterior chamber angle.
10 What is the main mechanism whereby pilocarpine reduces intraocular pressure? (A) Pronounced effect on ciliary muscle contraction; (B) Miosis opening up the trabecular meshwork; (C) Direct action on smooth muscle within the trabecular meshwork; (D) Encourages outflow via the uveo-scleral route.
The correct answer is A. The IOP-lowering effect of pilocarpine is now thought to be due to its more pronounced effect on ciliary muscle contraction.
11 Which receptor types predominate in the ciliary processes? (A) a1; (B) b1; (C) a2; (D) b2.
The correct answer is D. The ciliary muscle has predominantly b2 receptors.
12 Which of the following drugs reduces outflow via the uveo-scleral route? (A) Latanoprost; (B) Adrenaline; (C) Pilocarpine; (D) Travoprost.
The correct answer is C. Unlike the other three drugs, pilocarpine will actually reduce outflow via the uveoscleral route.
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