Glaucoma is not a single disease process but a group of disorders characterized by a progressive optic neuropathy resulting in a irreversible visual field defects that are associated frequently raised intraocular pressure (IOP).
IOP is the most common risk factor but not the only risk factor for development of glaucoma.
4. Aqueous humour is derived from capillary network of cilliary processes.
The normal aqueous production rate is 2.3 Âľl/min.
The 3 mechanisms ultra filtration, diffusion, and secretion (active
transport).
ULTRAFILTRATION
By ultra filtration, most of the plasma substances pass out from the capillary
wall, loose connective tissue and pigment epithelium of the cilliary
processes.
Thus, the plasma filtrate and accumulates behind the non pigment
epithelium of cilliary processes.
5. SECRETION
⢠The tight junctions between the cells of the non-pigment epithelium create part
of blood aqueous barrier.
⢠Certain substances are actively transported (secreted) across this barrier into the
posterior chamber.
⢠The active transport is brought about by Na+ K+ activated ATP pump and carbonic
anhydrase enzyme system.
⢠Substances that are actively transported include sodium, chlorides, potassium,
ascorbic acid, amino acids and bicarbonates.
DIFFUSION
⢠Active transport of these substances across the non-pigmented cilliary epithelium
results in an osmosis leading to the movement of other plasma constituents into
the posterior chamber by ultra filtration and diffusion.
⢠Sodium is primarily responsible for the movement of water into the posterior
chamber.
7. Aqueous humour flows from the posterior chamber into the anterior
chamber through the pupil. The aqueous is drained out by two routes â
1. TRABECULAR (CONVENTIONAL) OUTFLOW.
⢠Trabecular meshwork is the main part for aqueous outflow.
⢠Approx. 90 % aqueous is drained out via this route.
⢠Freely flow of aqueous occurs from trabecular meshwork up to inner
wall of Schlemm's canal.
⢠Mechanism of aqueous transport across inner wall of Schlemmâs canal.
⢠There are transcellular spaces in the endothelial cells forming inner
wall of Schlemm's canal.
⢠These open as a system of vacuoles and pores, primarily in response to
pressure, and transport the aqueous from the juxtacanalicular
connective tissue to Schlemmâs canal.
8. ⢠From Schlemm's canal the aqueous is transported via 25-35 external
collector channels into the episcleral veins by direct and indirect
systems.
⢠A pressure gradient between intraocular pressure and intrascleral
venous pressure is responsible for unidirectional flow of aqueous.
2. UVEOSCLERAL (UNCONVENTIONAL) OUTLOW.
It is responsible for about 10 percent of the total aqueous outflow.
Aqueous passes across the ciliary body into the suprachoroidal space
and is drained by the venous circulation in the ciliary body, choroid
and sclera.
12. ⢠The intraocular pressure (IOP) refers to the pressure exerted by intraocular
fluids on the coats of the eyeball.
⢠The normal IOP varies between 10 and 21 mm of Hg (mean 16 ¹ 2.5 mm
of Hg).
⢠The normal level of IOP is maintained by a balance between the formation
and outflow of the aqueous humour.
⢠Various factors influencing intraocular pressure can be grouped as under:
Local factors
⢠Rate of aqueous formation influences IOP levels.
⢠Increased episcleral venous pressure may result in rise of IOP.
⢠Dilatation of pupil in patients with narrow anterior chamber angle may
cause rise of IOP owing due to obstruction of the aqeuous drainage by the
iris.
13.
14. General factors
⢠Heredity
⢠Age. IOP increases after the age of 40 years due to reduced facility
of aqueous outflow.
⢠Postural variations. IOP increases when changing from the sitting to
the supine position.
⢠Osmotic pressure of blood. An increase in plasma osmolarity is
associated with a fall in IOP, while a reduction in plasma osmolarity
is associated with a rise in IOP. 8. General anaesthetics and many
other drugs also influence IOP .
16. ⢠Glaucoma is not a single disease process but a group of
disorders characterized by a progressive optic neuropathy
resulting in a irreversible visual field defects that are
associated frequently raised intraocular pressure (IOP).
⢠IOP is the most common risk factor but not the only risk factor
for development of glaucoma.
⢠The term âocular hypertensionâ is used for constantly raised
IOP without any glaucomatous damage.
⢠The term ânormal or low tension glaucomaâ (NTG/LTG) is used
for the cupping of the disc and/or visual field defects
associated with a normal or low IOP.
19. â˘Ocular hypertension or glaucoma suspect, when a patient has
an constantly increased IOP more than 21 mmHg but no optic
disc or visual field changes.
â˘These patients should be carefully monitored and should be
treated as cases of POAG.
High risk factors include:
â˘Significant diurnal variation - a difference of more than 8 mmHg
b/w the lowest & highest values of IOP.
â˘Positive water drinking provocative test.
â˘IOP constantly more than 28 mmHg.
20. ⢠NFL defects & Central corneal thickness < 555 ¾m.
⢠Asymmetry in the cup size of the two eyes, i.e., a difference of
more than 0.2.
⢠Strong family history of glaucoma.
⢠When associated with high myopia, diabetes or pigmentary
changes in the anterior chamber.
TREATMENT
⢠Patients with high-risk factors, should be to reduce IOP by 20%.
⢠Patients with no high risk factors should be annually followed
by examination of optic disc, perimetry and record of IOP.
Treatment is not required till glaucomatous damage is
documented
22. When typical glaucomatous disc changes with or without
visual field defects are associated with an IOP constantly below
21 mmHg.
ETIOLOGY
â˘It is associated with more common in NTG than in POAG :
peripheral vascular spasm on cooling, Migraine, Nocturnal
systemic hypotension and overtreated systemic hypertension.
â˘Reduced blood flow velocity in the ophthalmic artery.
23. CLINICAL FEATURES
â˘Optic disc changes & visual field defects are similar to POAG,
but the IOP is below 21mm Hg
TREATMENT
â˘Medical treatment to lower IOP. [Betaxolol]
â˘Other beta blockers and adrenergic drugs (such as
dipiverafrine) should better be avoided (as these cause systemic
hypotension and are the optic nerve perfusion).
â˘Trabeculectomy, Systemic calcium channel blockers (e.g.,
nifedipine) may be useful in patients with peripheral vasospasm.
And Monitoring of systemic blood pressure should be done for
24 hours.
26. â˘The congenital glaucoma are a group of disorders in
which abnormal high intraocular pressure.
â˘It results due to abnormalities of the angle of anterior
chamber obstructing the drainage of aqueous humour.
â˘It is not associated with any other ocular or systemic
anomaly.
â˘Sometimes, glaucoma may not occur until several years
after birth, but after some time, the term is
developmental glaucoma.
27. 1. True congenital glaucoma - IOP is raised during
intrauterine life.
2. Infantile glaucoma - the disease seen on child's third
birthday.
3. Juvenile glaucoma â IOP rise between 3-16 years of life.
⢠when the disease seems to age of 3 years, the
eyeball enlarges and so the term
buphthalmos (bull-like eyes) is used.
28.
29. CLINICAL FEATURES
⢠Photophobia, blepharospasm, lacrimation and eye rubbing.
⢠Corneal signs - oedema, enlargement and Descemetâs breaks.
⢠Sclera - thinning and appears blue in colour.
⢠Anterior chamber becomes deep.
⢠Iris may show iridodonesis.
⢠Lens becomes flat due to stretching of zonules and may
subluxate.
⢠Optic disc may show cupping and atrophy.
⢠IOP is raised.
⢠Axial myopia may give rise to anisometropic amblyopia.
30. EXAMINATION
⢠Measurement of IOP with Schiotz or Applanation tonometer.
⢠Measurement of corneal diameter.
⢠Ophthalmoscopy - to evaluate optic disc.
⢠Gonioscopic examination - angle of anterior chamber.
TREATMENT
⢠Congenital glaucoma is primarily surgical.
⢠IOP must be lowered by use of hyperosmotic agents,
acetazolamide and beta-blockers till surgery is taken up.
⢠Miotics are of no use in such cases.
32. ⢠It occurs in eyes with open angle of the anterior chamber.
⢠Primary open angle glaucoma (POAG) also known as chronic simple
glaucoma
⢠It is characterised by slowly progressive raised intraocular pressure (>21
mmHg ) associated with optic disc cupping and visual field defects.
ETIOLOGY
(A) Predisposing and risk factors.
1. Heredity.
2. Age. The risk increases with increasing age.
3. Race. POAG is more severe in black people than in white.
4. Myopic are more predisposed than the normal.
5. Diabetics, smoking & High blood pressure is the prevalence of POAG.
33.
34. Pathogenesis of rise in IOP.
⢠It is rise in IOP occurs due to decrease in the aqueous outflow
facility caused by age-related thickening and sclerosis of the
trabecular meshwork.
CLINICAL FEATURES
Symptoms
⢠Significant loss of visual field,
⢠Mild headache and eye ache.
⢠Reading and close work difficulties due to accommodative failure
⢠Frequent changes in presbyopic glasses, delayed dark adaptation.
35. Signs
âAnterior segment signs -
⢠Ocular examination by slit-lamp, may reveal normal anterior segment. In
late stages pupil reflex becomes sluggish and cornea show slight hazy.
âIntraocular pressure changes -
⢠Initially, the IOP may not be raised permanently. Therefore, repeated
observations of IOP (every 3-4 hour), for 24 hours is required during this
stage (Diurnal variation test). In most patients IOP falls during the evening.
⢠A variation in IOP of over 5 mm Hg (Schiotz) is suspicious and over 8 mm
of Hg is diagnostic of glaucoma.
⢠In later stages, IOP is permanently raised above 21 mm of Hg and ranges
between 30 and 45 mm of Hg.
36. â Optic disc changes -
⢠Optic disc changes, usually observed on routine fundus examination,
provide an important clue for suspecting POAG.
â Visual field defects -
⢠Visual field defects usually run parallel to the changes at the optic nerve
head and continue to progress if IOP is not controlled.
* Progression of visual field defects
⢠Isopter contraction.
⢠Baring of blind spot
⢠Small wing-shaped paracentral scotoma
⢠Seidelâs scotoma
⢠Arcuate or Bjerrumâs scotoma
⢠Ring or double arcuate scotoma
⢠Roenne's central nasal step.
37. INVESTIGATIONS
1. Tonometry. Applanation tonometry should be preferred
over Schiotz tonometry.
2. Diurnal variation test is especially useful in detection of
early cases.
3. Gonioscopy. It reveals a wide open angle of anterior
chamber.
5. Slit-lamp examination of anterior segment to rule out causes
of secondary open angle glaucoma.
6. Perimetry to detect the visual field defects.
7. Nerve fibre layer analyzer (NFL) helps in detecting the
glaucomatous damage to the retinal nerve fibres.
38. â Water drinking test.
⢠In it after an 8 hours fast, baseline IOP is noted and the patient is
asked to drink one litre of water and IOP is noted every 15 min. for 1
hour.
⢠The maximum rise in IOP occurs in 15-30 min. and returns to baseline
level after 60 minutes in both normal and the glaucomatous eyes.
⢠A rise of 8 mm of Hg or more is said to be diagnostic of POAG.
MANAGEMENT
Therapeutic choices include:
⢠Medical therapy
⢠Argon or diode laser trabeculoplasty
⢠Filtration surgery
40. ⢠It is a type of glaucoma in which rise in intraocular pressure occurs due to
blockage of the aqueous humour outflow by closure of a narrower angle of
the anterior chamber.
ETIOLOGY
(A) Predisposing risk factors
⢠Anatomical factors
⢠Hypermetropic eyes with shallow anterior chamber.
⢠Eyes with narrow angle, which may be due to: small eyeball, large size of
the lens and smaller diameter of the cornea or bigger size of the ciliary
body.
⢠General factors
⢠Age - PACG is comparatively more common in 5th decade of life.
⢠Gender - male to female ratio is 1:4.
41.
42. Mechanism of rise in IOP.
⢠First of all due to the effect of precipitating factors there occurs
mid dilatation of the pupil which & between iris and anteriorly
placed lens increases pressure.
⢠Consequently the aqueous collects in the posterior chamber
and pushes the peripheral iris, resulting angle closure due to
iridocorneal contact.
⢠The angle closure is converted into synechial angle closure.
⢠There are two main type of angle closure glaucoma -
1. Acute primary angle-closure glaucoma
2. Chronic primary angle-closure glaucoma
43. ACUTE PRIMARY ANGLE CLOSURE GLAUCOMA
⢠It occurs due to a sudden angle closure leading to severe rise in IOP.
CLINICAL FEATURES
Symptoms
⢠Severe pain in the eye.
⢠Nausea, vomiting and prostrations are frequently associated with pain.
⢠Sudden loss of vision, redness, photophobia and watering.
Signs
⢠Lids may be oedematous
⢠Conjunctiva is chemosed, and congested and Corneal oedema and
insensitive.
⢠AC is very shallow & Aqueous flare or cells may be seen in anterior
chamber.
44. ⢠Angle of anterior chamber is completely closed as seen on gonioscopy.
⢠Iris may be discoloured.
⢠Pupil is semi-dilated and non-reactive to light
⢠IOP is markedly elevated, usually between 40 and 70 mm of Hg.
⢠Optic disc is oedematous and hyperaemic.
⢠Fellow eye shows shallow anterior chamber and a narrow angle (latent
angle closure glaucoma).
MANAGEMENT
1. Medical therapy
2. Surgical treatment
⢠Peripheral iridotomy
⢠Filtration surgery
45. CHRONIC PRIMARY ANGLE CLOSURE GLAUCOMA
Pathogenesis
It results from gradual synechial closure of the angle of anterior
chamber.
Clinical features
⢠Intraocular pressure (IOP) remains constantly raised.
⢠Eyeball remains white (no congestion) and painless
⢠Optic disc may show glaucomatous cupping.
⢠Gonioscopy reveals a permanent peripheral anterior synechiae.
Treatment
⢠Laser iridotomy alone or along with medical therapy should be tried.
⢠Trabeculectomy (filtration surgery) is needed when the above
treatment fails to control IOP.
47. Secondary glaucoma is not a disease entity, but a group of disorders in
which rise of IOP is associated with primary ocular or systemic disease.
1. Lens-induced glaucoma.
2. Inflammatory glaucoma (due to intraocular inflammation/uveitis).
3. Pigmentary glaucoma.
4. Neovascular glaucoma.
5. Glaucoma associated with intraocular haemorrhage.
6. Steroid-induced glaucoma.
7. Traumatic glaucoma.
8. Glaucoma-in-aphakia.
9. Glaucoma associated with intraocular tumours.
48. PHACOLYTIC GLAUCOMA (LENS PROTEIN GLAUCOMA)
Pathogensis. in which trabecular meshwork is blocked by the lens
proteins and macrophages which have phagocytosed the lens proteins.
Leakage of the lens proteins occurs in hypermature cataract .
Clinical features
Features of congestive glaucoma due to an acute rise of IOP in an eye
having hypermature cataract.
Anterior chamber may become deep and aqueous may contain fine
white protein particles.
Management
It consists of medical therapy to lower the IOP followed by extraction of
the hypermature cataractous lens with PCIOL implantation.
49. LENS INDUCED GLAUCOMA
Pathogenesis
It is a type of glaucoma, in which trabecular meshwork is
blocked by the lens particles floating in the aqueous humour.
It may occur due to lens particles left after accidental or
planned ECCE surgery or traumatic rupture of the lens.
Clinical features Raised IOP associated with lens particles in
the anterior chamber.
Management includes medical therapy to lower IOP and
irrigation-aspiration of the lens particles from the anterior
chamber
50. GLAUCOMAS DUE TO UVEITIS or INFLAMMATORY GLAUCOMA
The IOP can be raised by inflammations of the uveal tissue (iridocyclitis).
other ocular inflammations such as keratitis and scleritis.
Types - It can be divided into two main groups:
1. Hypertensive uveitis.
2. Post-inflammatory glaucoma.
Hypertensive uveitis
It refers to acute inflammation of the anterior uvea associated with
raised IOP.
It includes:
i. Non-specific hypertensive uveitis
ii) Specific hypertensive uveitis
51. i. Non-specific hypertensive uveitis.
â˘It includes inflammation of the anterior uveal tract associated with
raised IOP.
â˘Mechanisms of rise in IOP - occurs due to trabecular clogging
(blocking) by inflammatory cells and trabecular oedema due to
trabeculitis), and prostaglandinâinduced rise in IOP.
Management - It includes treatment of iridocyclitis and medical
therapy to lower IOP by use of hyperosmotic agents, acetazolamide
and beta- blocker eye drops.
ii. Specific hypertensive uveitis
These include: Fuchsâ uveitis syndrome and Glaucomatocyclitic crisis.
52. 2. Post-inflammatory glaucoma
â˘IOP is raised due to after-effects of the iridocyclitis.
Mechanisms of rise in IOP
â˘Pupillary block due to annular synechiae,
â˘Secondary glaucoma with pupil block following iris bombe
formation.
â˘Secondary glaucoma due to inflammatory debris in the
angle.
â˘Secondary glaucoma due to trabecular scarring and
obstruction of the meshwork.
53. Management.
It includes prophylaxis and curative treatment.
1. Prophylaxis - Acute iridocylitis should be treated with local
steroids and atropine to prevent formation of synechiae.
2. Curative treatment - It consists of medical therapy to lower
IOP (miotics are contraindicated). Surgical or laser
iridotomy may be useful in pupil block without angle
closure
54. PIGMENTARY GLAUCOMA
It is a type of glaucoma in which blocking of trabecular meshwork by the
pigment particles.
Pathogenesis
Some pigment release is caused by mechanical rubbing of the posterior
pigment layer of iris with the zonular fibrils.
Clinical features
The condition typically occurs in young myopic males.
It is associated with deposition of pigment granules in the anterior segment
structures such as iris, posterior surface of the cornea, trabecular
meshwork, ciliary zonules and the crystalline lens.
Gonioscopy shows pigment accumulation along the Schwalbeâs line.
Treatment
Same as primary open angle glaucoma.
55. NEOVASCULAR GLAUCOMA (NVG)
It occurs due to formation of neovascular membrane involving
the angle of anterior chamber.
Etiology
â˘It is usually associated with neovascularization of iris. [rubeosis
iridis]
â˘Neovascularization develops following retinal ischaemia, which
is a common feature of :
â˘Diabetic retinopathy, Central retinal vein occlusion, Sickle-cell
retinopathy and Ealesâ disease.
⢠Other rare causes are chronic intraocular inflammations,
intraocular tumours, retinal detachment and central retinal
artery occlusion.
56. Clinical profile NVG occurs in three stages :
1. Pre-glaucomatous stage (stage of rubeosis iridis);
2. Open-angle glaucoma stageâ due to formation of a
pretrabecular neovascular membrane
3. Secondary angle closure glaucomaâ due to goniosynechiae
resulting from contracture of the neovascular membrane.
Treatment
â˘Panretinal photocoagulation, prevent further neovascularization.
â˘Medical therapy are usually not effective in controlling the IOP.
â˘Artificial filtration shunt (Seton operation) may control the IOP
57. GLAUCOMAS DUE TO INTRAOCULAR HAEMORRHAGES
Intraocular haemorrhages include hyphaema or vitreous haemorrhage due to
multiple causes.
1. Red cell glaucoma - It is associated with fresh traumatic hyphaema. It is
caused by blockage of trabeculae by RBCs in patients with hyphaema
(anterior chamber full of blood).
2. Haemolytic glaucoma - It occurs due to the obstruction of the trabecular
meshwork caused by macrophages.
3. Ghost cell glaucoma - It occurs in aphakic or pseudo phakic eyes with
vitreous haemorrhage.
After about 2 weeks of haemorrhage the RBCs degenerate, lose
their pliability and become khaki-color cells (ghost cells) which
pass from the vitreous into the anterior chamber, and block the
pores of trabeculae leading to rise in IOP.
58. STEROID-INDUCED GLAUCOMA
It is a type of glaucoma which develops following topical, and
sometimes systemic steroid therapy.
Etiopathogenesis.
â˘It develop marked rise of IOP after about 6 weeks of steroid
therapy.
Following theories have been put forward :
â˘Glycoaminoglycans (GAG) theory
â˘Endothelial cell theory
â˘Prostaglandin theory
59. Clinical features
Steroid-induced glaucoma usually develops following weeks of
topical therapy with strong steroids and months of therapy
with weak steroids.
Management
It can be prevented by a proper use of steroids and a regular
monitoring of IOP.
Its treatment consists of - Discontinuation of steroids
60. TRAUMATIC GLAUCOMA
A secondary glaucoma may complicate perforating as well as blunt
injuries.
Mechanisms
Traumatic glaucoma may develop by -
â˘Inflammatory glaucoma due to iridocyclitis
â˘Glaucoma due to intraocular haemorrhage
â˘Lens-induced glaucoma due to ruptured, swollen or dislocated lens.
â˘Angle-closure due to peripheral anterior synechiae formation
following perforating corneal injury producing adherent leucoma.
â˘Angle recession (cleavage) glaucoma due to disruption of
trabecular meshwork followed by fibrosis.
61. Management
It consists of medical therapy with topical timolol and
oral acetazolamide.
Treatment of associated causative mechanism (e.g.
atropine and steroids for control of inflammation) and
surgical intervention according to the situation.
62. GLAUCOMA-IN-APHAKIA/PSEUDOPHAKIA
It includes following conditions:
â˘Raised IOP with deep anterior chamber in early postoperative
period, may be due to hyphaema, inflammation, vitreous filling
the anterior chamber.
â˘Secondary glaucoma due to flat anterior chamber.
â˘Secondary glaucoma due to pupil block due to formation of
annular synechiae.
63. GLAUCOMA ASSOCIATED WITH INTRAOCULAR TUMOURS
Secondary glaucoma due to intraocular tumours such as malignant
melanoma (iris, choroid, ciliary body) and retinoblastoma may occur
by -
⢠Trabecular block due to clogging [blocking] by tumour cells or
direct invasion by tumour seedlings.
⢠Neovascularization of the angle.
⢠Venous stasis following obstruction of the vortex veins.
⢠Angle closure due to forward displacement of iris-lens diaphragm
by increasing tumour mass.
Treatment
Enucleation of the eyeball should be carried out as early as possible.