Download MBBS Ophthalmology PPT 47 Primary Open Angle Glaucoma Lecture Notes

--- Content provided by​ FirstRanker.com ---

Acknowledgement

? Kanski's Clinical Ophthalmology (8th Edition).

--- Content provided by⁠ FirstRanker.com ---

? Becker- Schaffer's Diagnosis and therapy of The

Glaucomas (8th Edition).

? Comprehensive Ophthalmology (A.K.Khurana)

--- Content provided by‍ FirstRanker.com ---

(7th Edition).

2

--- Content provided by‌ FirstRanker.com ---

Learning Objectives

? At the end of this class the students shall be able to :
? Define primary open angle glaucoma(POAG).

--- Content provided by‌ FirstRanker.com ---

? Comprehend the pathophysiology and
risk factors of POAG.
? Understand the clinical features of POAG.
? Understand the fundamentals of managing
primary open angle glaucoma

--- Content provided by⁠ FirstRanker.com ---

3

4
Question

--- Content provided by‍ FirstRanker.com ---

Glaucoma is defined as:
? a. a group of diseases that have in common a

characteristic optic neuropathy associated with increased

--- Content provided by⁠ FirstRanker.com ---

intraocular pressure.

? b. a group of diseases that have in common a

--- Content provided by‍ FirstRanker.com ---

characteristic optic neuropathy with associated visual

function loss.

? c. a group of diseases that have in common high

--- Content provided by FirstRanker.com ---

intraocular pressure with or without optic neuropathy.

? d. a group of diseases that have in common a

--- Content provided by⁠ FirstRanker.com ---

characteristic optic neuropathy with poor visual acuity.

5

Definition of POAG

--- Content provided by​ FirstRanker.com ---

? Chronic, progressive optic neuropathy

characterised by morphological changes at the

--- Content provided by⁠ FirstRanker.com ---

optic disc and retinal nerve fibre layer leading to

characteristic visual field changes, in the absence

of other ocular diseases or congenital anomalies

--- Content provided by⁠ FirstRanker.com ---

(with or without a raised IOP).

6
Etiopathogenesis

--- Content provided by​ FirstRanker.com ---

? Multifactorial aetiology
? Risk factors include:

? Elevated Intra Ocular Pressure(IOP)

--- Content provided by⁠ FirstRanker.com ---

(More than 21 mm Hg)

? Optic disc cupping

--- Content provided by​ FirstRanker.com ---

? Increasing Age : More common in 5th to 7th decades

? Race: More common and severe in Black population

7

--- Content provided by⁠ FirstRanker.com ---

Etiopathogenesis

? Heredity/ Family History: Risk of about 10% in

--- Content provided by FirstRanker.com ---

siblings; 4% in off springs

? Diabetes

? Systemic Hypertension

--- Content provided by FirstRanker.com ---

? Myopia

? Thin central corneas

--- Content provided by FirstRanker.com ---

? Steroid usage

? ?Migraine, Cigarette smoking

8

--- Content provided by​ FirstRanker.com ---

Pathophysiology of POAG

? Decrease in aqueous outflow facility due to

--- Content provided by‌ FirstRanker.com ---

increased resistance to outflow leads to rise in IOP

? Two theories of axonal loss in optic disc
? 1. Mechanical: Distortion of lamina cribrosa

--- Content provided by⁠ FirstRanker.com ---

leading to impaired axoplasmic flow

2. Vascular: Optic disc ischaemia with
defective autoregulation of blood vessels

--- Content provided by⁠ FirstRanker.com ---

9

FORMATION OF AQUEOUS HUMOR

--- Content provided by‍ FirstRanker.com ---

CILIARY PROCESSES

-approx. 70-80 radial folds in the pars plicata which form

the site of aqueous production.

--- Content provided by​ FirstRanker.com ---

-Zonular fibers attach primarily in the valleys of the ciliary

processes and also along the pars plana

--- Content provided by​ FirstRanker.com ---

DIFFUSION

SECRETION
(80-90%)

--- Content provided by⁠ FirstRanker.com ---

ULTRA-
FILTRATION

FORMATION PROCESSES 11

--- Content provided by‍ FirstRanker.com ---

Formation of aqueous humor

? Diffusion and ultrafiltration are both

--- Content provided by⁠ FirstRanker.com ---

passive mechanisms so no active cellular

participation occurs.

? Active secretion is an active process.

--- Content provided by FirstRanker.com ---

? Rate of formation of aqueous humor in a

healthy human eye is-

--- Content provided by⁠ FirstRanker.com ---

2 - 3 microlitres/minute

12
Table 1. Constituents of Human Aqueous Humor*

--- Content provided by‌ FirstRanker.com ---

Constituent (?mol/mL) Anterior Chamber

Aqueous

Plasma

--- Content provided by‍ FirstRanker.com ---

Ascorbate

1.06

--- Content provided by‌ FirstRanker.com ---

0.04

Bicarbonate

22.0

--- Content provided by FirstRanker.com ---

26.0

Calcium

--- Content provided by⁠ FirstRanker.com ---

2.5

4.9

Chloride

--- Content provided by​ FirstRanker.com ---

131.0

107.0

--- Content provided by​ FirstRanker.com ---

Glucose

2.8

5.9

--- Content provided by FirstRanker.com ---

Lactate

4.5

--- Content provided by‍ FirstRanker.com ---

1.9

Magnesium

1.2

--- Content provided by‌ FirstRanker.com ---

1.2

Phosphate

--- Content provided by​ FirstRanker.com ---

0.6

1.1

Potassium

--- Content provided by​ FirstRanker.com ---

22.0

26.0

--- Content provided by‌ FirstRanker.com ---

Sodium

152.0

148.0

--- Content provided by​ FirstRanker.com ---

Urea

6.1

--- Content provided by FirstRanker.com ---

7.3

Protein (gm/dL)

0.024

--- Content provided by‌ FirstRanker.com ---

7.0

pH

--- Content provided by‌ FirstRanker.com ---

7.21

7.4

13

--- Content provided by FirstRanker.com ---

Differences between

aqueous humor & plasma

--- Content provided by FirstRanker.com ---

AQUEOUS PLASMA

-Marked deficit of

0.024 7.0

--- Content provided by‍ FirstRanker.com ---

proteins

gm/dl gm/dl

--- Content provided by‍ FirstRanker.com ---

-Marked excess of

1.06 0.04

Ascorbate

--- Content provided by‍ FirstRanker.com ---

micromol/ml micromol/ml

--- Content provided by‌ FirstRanker.com ---

-Excess of Lactate

4.5 1.9

micromol/ml micromol/ml

--- Content provided by‌ FirstRanker.com ---

-Excess of Chloride &

certain amino acids

--- Content provided by‌ FirstRanker.com ---

14
Functions of aqueous humor

*Maintaining IOP :
-important for early ocular development &

--- Content provided by‍ FirstRanker.com ---

maintaining global integrity throughout life.
*Serves as a vascular system for the avascular
structures of the eye: cornea, lens & TM.
- by providing substrates & nutrients & removing
metabolites.

--- Content provided by‍ FirstRanker.com ---

15

Functions of aqueous humor

--- Content provided by FirstRanker.com ---

*Delivering high concentration of Ascorbate:

- scavenges free radicals & protects against UV

rays & other radiations.

--- Content provided by​ FirstRanker.com ---

*Local paracrine signaling & immune responses.

*Colourless & transparent medium as part of eye's

--- Content provided by‌ FirstRanker.com ---

optical system.

16

--- Content provided by‌ FirstRanker.com ---

Aqueous humor outflow

17

Video of aqueous humor outflow

--- Content provided by‌ FirstRanker.com ---

18


Major amount of aqueous humor leaves the

--- Content provided by⁠ FirstRanker.com ---

eye by


BULK FLUID FLOW

--- Content provided by‌ FirstRanker.com ---

i.e. fluid flows along normal pressure

gradient through non-energy dependent

--- Content provided by​ FirstRanker.com ---

process

19

Ciliary processes

--- Content provided by⁠ FirstRanker.com ---

Aqueous Humor in PC

--- Content provided by‍ FirstRanker.com ---

through pupil

Anterior Chamber

--- Content provided by FirstRanker.com ---

20


Trabeculo-canalicular outflow

--- Content provided by​ FirstRanker.com ---

*It is the main outlet for aqueous from the AC

*70-90% of total aqueous is drained by this route

TRABECULAR MESHWORK

--- Content provided by​ FirstRanker.com ---

-A sponge work of
connective tissue
beams arranged as
super-imposed

--- Content provided by FirstRanker.com ---

perforated sheets.
- Extracellular spaces
contain hydrophilic

glycosaminoglycans &

--- Content provided by FirstRanker.com ---

collagen.

22

--- Content provided by FirstRanker.com ---

JUXTACANALICULAR

(ENDOTHELIAL) MESHWORK

--- Content provided by⁠ FirstRanker.com ---

- Outermost portion of

TM which mainly

offers the normal

--- Content provided by‌ FirstRanker.com ---

resistance to

aqueous outflow

--- Content provided by⁠ FirstRanker.com ---

- Connects the

corneoscleral

meshwork with

--- Content provided by‌ FirstRanker.com ---

schlemm's canal

23

--- Content provided by⁠ FirstRanker.com ---

? Veins from the anterior part of ciliary body form the

Ciliary venous plexus

--- Content provided by‌ FirstRanker.com ---

Anterior ciliary veins & Episcleral veins

communicate with Schlemm's canal

--- Content provided by​ FirstRanker.com ---

24
Schlemm's Canal

--- Content provided by‌ FirstRanker.com ---

20-30 Collector channels Aqueous Vein

Intra-scleral venous plexus

--- Content provided by‌ FirstRanker.com ---

Episcleral venous plexus
& Anterior Ciliary vein

25

--- Content provided by‍ FirstRanker.com ---

UNCONVENTIONAL

OUTFLOW

*responsible for 10-25% of total aqueous outflow

--- Content provided by​ FirstRanker.com ---

UVEO-SCLERAL OUTFLOW

27

--- Content provided by‍ FirstRanker.com ---

Trans-corneal outflow

- Aqueous humor from anterior chamber

--- Content provided by⁠ FirstRanker.com ---

goes into tear film through cornea.

- Very little aqueous passes through this

pathway.

--- Content provided by‌ FirstRanker.com ---

- Total volume of fluid transferred is limited

by high hydraulic resistance of the cornea.

--- Content provided by⁠ FirstRanker.com ---

28
Clinical features of POAG

Symptoms
? Usually asymptomatic in early cases

--- Content provided by‍ FirstRanker.com ---

? Mild headache and eye ache
? Frequent changes in presbyopic glasses
? Delayed dark adaptation
? Loss of peripheral vision
? Loss of central vision(late cases)

--- Content provided by​ FirstRanker.com ---

29

Signs of POAG

--- Content provided by​ FirstRanker.com ---

? Normal anterior segment
? Pupil reaction to light may be sluggish(in

advanced cases only)

--- Content provided by FirstRanker.com ---

? Elevated IOP(More than 21 mm Hg) with

diurnal variation more than 5-8 mmHg

? Optic disc changes (Progressive,

--- Content provided by‍ FirstRanker.com ---

asymmetric)

? Visual field defects

--- Content provided by FirstRanker.com ---

30


31

--- Content provided by FirstRanker.com ---

Optic disc changes in glaucoma

? Early changes
o Retinal nerve fibre layer atrophy

--- Content provided by FirstRanker.com ---

o Vertically oval cup

o Asymmetry of the cups(More than 0.2

difference)

--- Content provided by​ FirstRanker.com ---

o Large cup(CD more than 0.6)

o Splinter haemorrhages

--- Content provided by‌ FirstRanker.com ---

32


Advanced glaucomatous disc changes

--- Content provided by FirstRanker.com ---

? Marked cupping (More than 0.7)
? Thinning of NRR (Neuroretinal rim)
? Lamellar dot sign
? Vascular alterations
o Nasal shifting of retinal vessels

--- Content provided by⁠ FirstRanker.com ---

o Bayonetting sign(convoluted path due to NRR

loss)

--- Content provided by​ FirstRanker.com ---

o Baring of circumlinear vessels and overpass

vessels

? Glaucomatous optic atrophy

--- Content provided by​ FirstRanker.com ---

33

Normal Optic Disc

--- Content provided by FirstRanker.com ---

Glaucomatous optic disc

34

--- Content provided by‌ FirstRanker.com ---

Is this a normal or

Glaucomatous optic disc

glaucomatous disc ?

--- Content provided by⁠ FirstRanker.com ---

35

Recording and documenting disc changes

--- Content provided by‌ FirstRanker.com ---

? Serial drawings (10 square grid) after

seeing fundus by ophthalmoscopy/slit

lamp with +90D/+78D lens

--- Content provided by FirstRanker.com ---

? Disc photography
? HRT(Heidelberg retinal tomography)
? OCT (Optical coherence tomography)
? NFA(Nerve fibre analyser)

--- Content provided by‍ FirstRanker.com ---

36


View of optic disc by 90D lens examination

--- Content provided by​ FirstRanker.com ---

37

Field of vision

--- Content provided by FirstRanker.com ---

38
Visual field defects in glaucoma

? Arcuate nerve fibres in the superior and

--- Content provided by​ FirstRanker.com ---

inferior temporal portions of the optic disc:

Most sensitive to damage
? Macular fibres : Most resistant to damage

--- Content provided by⁠ FirstRanker.com ---

CENTRAL VISION IS PRESERVED TILL

THE LAST IN GLAUCOMA

39

--- Content provided by⁠ FirstRanker.com ---

Progression of field defects

? Isopter contraction: Generalised field

--- Content provided by FirstRanker.com ---

constriction

? Baring of blind spot : Non specific
(Exclusion of blind spot from central field)
? Paracentral scotoma: Wing shaped and

--- Content provided by‌ FirstRanker.com ---

occurs above or below the blind spot in the

Bjerrum's area(10-25 degrees from

--- Content provided by⁠ FirstRanker.com ---

fixation)

Is the earliest clinically significant defect

40

--- Content provided by⁠ FirstRanker.com ---

Progression of field defects

? Seidel's scotoma: sickle shaped
Due to joining of blind spot and
paracentral scotoma

--- Content provided by​ FirstRanker.com ---

? Bjerrum's/Arcuate scotoma:
Extension of Seidel's scotoma to reach the
horizontal line.
? Double arcuate/ring scotoma

--- Content provided by‌ FirstRanker.com ---

41

Progression of field defects

--- Content provided by​ FirstRanker.com ---

? Roenne's central nasal step:
Sharp right angled defect at the horizontal
meridian when arcuate scotomas run in
different arcs
? Peripheral field defects

--- Content provided by‌ FirstRanker.com ---

? Advanced defects
Residual Tubular vision
Temporal island of vision

42

--- Content provided by‌ FirstRanker.com ---

Quantification of visual field defects

? Visual field analyzer

--- Content provided by FirstRanker.com ---

Kinetic perimeter
Static perimeter (automated)

Testing more than once is required before
final interpretation

--- Content provided by‌ FirstRanker.com ---

43

Enlarged blind spot

--- Content provided by⁠ FirstRanker.com ---

44


Superior arcuate scotoma

--- Content provided by‌ FirstRanker.com ---

45

Bjerrum's scotoma

46

--- Content provided by‍ FirstRanker.com ---

Roenne's nasal step

47

--- Content provided by FirstRanker.com ---

Double arcuate

10-2- Advanced VFD , macular split

--- Content provided by⁠ FirstRanker.com ---

48


Advanced glaucoma

--- Content provided by FirstRanker.com ---

49

Diagnostic work up/Investigations

? Tonometry

--- Content provided by FirstRanker.com ---

? Goniscopy: Open angles
? Perimetry: To detect visual field defects
? Slit lamp examination: To rule out causes

of secondary open angle glaucoma

--- Content provided by‌ FirstRanker.com ---

? Fundus examination to document optic

disc changes

--- Content provided by‌ FirstRanker.com ---

? Diurnal variation testing
? Provocative testing: Water drinking test 50
Diagnosis

? POAG: Raised IOP(More than 21 mm Hg),

--- Content provided by FirstRanker.com ---

glaucomatous optic disc cupping, visual
field changes.
? Ocular hypertension/glaucoma suspect:
Raised IOP
? NTG(Normal tension glaucoma):

--- Content provided by​ FirstRanker.com ---

Glaucomatous optic disc cupping with or
without visual field changes with normal IOP


51

--- Content provided by FirstRanker.com ---

Management of POAG

? Therapeutic choices

--- Content provided by FirstRanker.com ---

q Medical therapy

q Argon/Diode Laser Trabeculoplasty

q Filtration surgery

--- Content provided by​ FirstRanker.com ---

52
Basic principles of therapy

? Make a correct diagnosis

--- Content provided by⁠ FirstRanker.com ---

? Set a target IOP
? Start with a single drug to lower IOP
? Switch to another group of drugs if needed
? Control IOP on minimal medications
? Monitor therapy and reset target IOP

--- Content provided by FirstRanker.com ---

whenever needed

53

--- Content provided by FirstRanker.com ---

Topical drugs used for POAG therapy

? Prostaglandin/Prostamides
Latanoprost, Bimatoprost, Travoprost
? Beta blockers

--- Content provided by⁠ FirstRanker.com ---

Timolol maleate, Betaxolol
? Carbonic anhydrase inhibitors
Dorzolamide, Brinzolamide
? Sympathomimetics
Brimonidine, Apraclonidine

--- Content provided by​ FirstRanker.com ---

? Parasympathomimetics
Pilocarpine

54
Systemic drugs used for POAG therapy

--- Content provided by‌ FirstRanker.com ---

? Used rarely, for short term control of IOP
? Oral carbonic anhydrase inhibitors
Acetazolamide, Methazolamide

--- Content provided by‌ FirstRanker.com ---

55

Laser treatment

? Indications

--- Content provided by‍ FirstRanker.com ---

Target IOP not achieved with medical
therapy
Non compliance of medical therapy

Argon/ Diode Laser Trabeculoplasty (ALT)

--- Content provided by FirstRanker.com ---

Selective Laser Trabeculoplasty (SLT)

56
Surgical therapy

--- Content provided by‌ FirstRanker.com ---

? Indications
v Target IOP not achieved with maximal
tolerated medical therapy and laser
trabeculoplasty
v Non compliance of medical therapy

--- Content provided by⁠ FirstRanker.com ---

v Non availability of laser therapy
v Advanced glaucoma

57

--- Content provided by​ FirstRanker.com ---

Surgical therapy

? Filtration surgery : Trabeculectomy

--- Content provided by FirstRanker.com ---

? Modified trabeculectomy :
Use of antifibrotic agents
Mitomycin/5FU
? Aqueous drainage devices:
Ahmed glaucoma valve

--- Content provided by​ FirstRanker.com ---

In cases with no/poor visual potential:
Cycloablative therapy with laser/cryotherapy

58
Conclusion

--- Content provided by‌ FirstRanker.com ---

? Primary open angle glaucoma is a

progressive optic neuropathy with

--- Content provided by‍ FirstRanker.com ---

characteristic optic disc and visual field

changes.

? Increased resistance to aqueous outflow

--- Content provided by‍ FirstRanker.com ---

leads to rise in IOP.

? Aim of management is to reduce IOP to

--- Content provided by‌ FirstRanker.com ---

minimize damage to optic disc and

resultant visual field defects.

59

--- Content provided by⁠ FirstRanker.com ---

Question

Which of the fol owing is not a risk factor

--- Content provided by‍ FirstRanker.com ---

for the development of primary open

angle glaucoma?
a. positive family history.
b. advanced age.

--- Content provided by‌ FirstRanker.com ---

c. increased IOP.
d. increased corneal thickness.

60

--- Content provided by FirstRanker.com ---

Question

You have been referred a case of open

--- Content provided by​ FirstRanker.com ---

angle glaucoma. Which of the fol owing

would be an important point in

diagnosing the case?

--- Content provided by FirstRanker.com ---

a. Shallow anterior chamber
b. Optic disc cupping
c. Narrow angle
d. Visual acuity and refractive error

--- Content provided by‍ FirstRanker.com ---

61

THANK YOU

62

--- Content provided by FirstRanker.com ---