Anterior Segment

Question 1

Three Mechansims (3)

Answer 1

1. active secretion( take place in the double layered ciliary epithelium )
2. ultrafiltration
3. simple diffusion

Question 2

what is active transport

Answer 2

Ac tive secretion refers to transport that requires energy to move sodium, chloride, bicarbonate, and other ions, which are currently unknown, against an electrochemical gradient. Active secretion is independent of pressure and accounts for the majority of aqueous production. It involves, at least in part, activity of the enzyme carbonic anhydrase II.

Question 3

what is ultrafiltration

Answer 3

refers to a pressure-dependent movement along a pressure gradient. In the ciliary processes, the hydrostatic pressure difference between capillary pressure and IOP favors fluid movement into the eye, whereas the oncotic gradient between the two resists fluid movement. The relationship between secretion and ultrafiltration is not known.

Question 4

simple diffusion

Answer 4

Diffusion involves the passive movement of ions, based on charge and
concentration, across a membrane.

Question 5

how does rate of aqueous humor affected (3)

Answer 5

1. decreases by half during sleep.

2. It also decreases with age.

Question 6

he rate of aqueous formation is affected by a variety of factors, including the following:

Answer 6

1. integrity of the blood–aqueous barrier
2. blood flow to the ciliary body
3. neurohumoral regulation of vascular tissue and the ciliary epithelium.
4. production may decrease after trauma 5. or intraocular inflammation and after the administration of certain drugs (eg, general anesthetics and some systemic hypotensive agents). 6. Carotid occlusive disease may also decrease aqueous humor production.

Question 7

optical principles of gonioscopy

Answer 7

Total internal reflection can prevent rays illuminating the angle from passing back through the cornea where they can be seen.

1. Index matching corneal lenses can permit direct illuminated views of the angle
2. Index matching lenses with reflective surfaces can permit indirect views as well

Question 8

direct lenses of gonioscopy

Answer 8

the light ray reflected from the anterior chamber angle is observed directly

Question 9

why dynamic gonioscopy is essential ?

Answer 9

the technique of dynamic gonioscopy is sometimes essential for distinguishing iridocorneal apposition from synechial closure. Many clinicians prefer these lenses because of their ease of use and employment in performing dynamic gonioscopy.

Question 10

the spaeth system works on :

Answer 10

1. Where is the iris insertion
2. What is the angular width (degrees)
3. What is the contour of the iris
4. Level of pigmentation (1-4)

Question 11

layers of the trabecular meshwork

Answer 11

uveal, corneoscleral, and juxtacanalicular

Question 12

the uveal meshwork

Answer 12

The uveal trabecular meshwork is adjacent to the anterior chamber and is arranged in bands that extend from the iris root and the ciliary body to the peripheral cornea.

Question 13

The corneoscleral meshwork

Answer 13

The corneoscleral meshwork consists of sheets of trabeculum that extend from the scleral spur to the lateral wall of the scleral sulcus.

Question 14

juxtacanalicular meshwork

Answer 14

The juxtacanalicular meshwork, which is thought to be the major site of outflow resistance, is adjacent to and actually forms the inner wall of the Schlemm canal.

Question 15

1. Where is the iris insertion

Answer 15

A—narrow; anterior to the trabecular meshwork
 9
B—behind Schwalbe line 
C—Posterior to the scleral spur 
D—deep into the cilary body face 
E—extremely deep cilary body

Question 16

3. What is the contour of the iris

Answer 16

F—flat
B—bowed
C—concave
P—platea

Question 17

The gonioscopic criteria for diagnosing angle recession include (4)

Answer 17

1. an abnormally wide ciliary body band (Fig 3-8)
2. increased prominence of the scleral spur
3. torn iris processes
4. marked variation of ciliary face width and angle depth in different quadrants of the same eye

Question 18

Angle

recession

Answer 18

tear between longitudinal and circular muscles of ciliary

body

Question 19

Cyclodialysis

Answer 19

(separation of ciliary body from scleral spur) with widening of suprachoroidal space

Question 20

iridodialysis

Answer 20

(tear in root of

iris).

Question 21

Trabecular damage

Answer 21

(tear in anterior portion of meshwork, creating a flap that is hinged at the scleral spur)

Question 22

The gonioscopic criteria for diagnosing angle recession include (4)

Answer 22

1. an abnormally wide ciliary body band (Fig 3-8)
2. increased prominence of the scleral spur
3. torn iris processes
4. marked variation of ciliary face width and angle depth in different quadrants of the same eye

Question 23

what other findings that are visible by gonioscpy

Answer 23

1. microhyphema or hypopyon
2. retained anterior chamber foreign body
3. iridodialysis
4. sclerostomy site and tube shunts
5. angle precipitates suggestive of glaucomatocyclitic crisis 6. pigmentation of the lens equator
6. other peripheral lens abnormalities
7. intraocular lens haptics 9. ciliary body tumors/cys

Question 24

how to distinguish PAS from iris processes

Answer 24

iris processes (the uveal meshwork), which are open and lacy and follow the normal curve of the angle. The angle structures are visible in the open spaces between the processes. Synechiae are more solid or sheetlike (Fig 3-7). They are composed of iris stroma and obliterate the angle recess.