• 450 BC: HIPPOCRATES describe HEMIANOPIA
• 150 BC: Ptolemy estimating the outer limits of the Visual field
• 1668: EDME MARIOTTE discover blind spot.
• 1856: Clinically campimetry first started by Graefe.
• 1851-1920: Prof.J.P.Bejerrum of Copenhagen devised Tangent screen. He drew his first screen on the back of his door. He also first described Arcuate scotoma, Bjerrum/Tangent screen was popular in USA for 100 years.
• 1869: Forster and Aubert developed an arc perimeter. It was very popular and became known as Forster perimeter.
• 1945: First Cupola perimetry was designed by Professor. Hans Goldman, Bern.
• First Automated Static perimetry also came out from Switzerland, Bern.
• First Automated Octopus 201 in late 1970 room size costing excess of US $ 100000 for unknown technology. And high cost kept perimetry in “IVORY TOWER”.
• 1982: First Humphrey field analyzer was displayed at “AAO”
• 1983: Production unit delivery began. Because of small size & low cost the machine became very popular
  

Key Issue

Understanding the Principles

HUMPHREY IS GOLD STANDARD

• To learn about perimetry is to understand the basic characteristics of the visual field.
• With this knowledge the data and the results from all perimeters can be interpreted.

GOOD THINGS ARE CHEAP BUT CHEAP THINGS ARE NOT GOOD

STATIC vs KINETIC

WHAT IS PERIMETRY

Is the measurement of the differential light Sensitivity of the retina at a defined number of Locations.

WHEN WILL YOU SEND A PATIENT FOR FIELD?

• ELEVATED IOP
• SUSPECTED OPTIC NERVE
• ASYMMETRIC CUP:DISC > 0 .3
• IOP DIFFERS 3mmHg FROM OTHER EYE
• UNEXPLAINED LOW VISUAL ACUITY
• UNEXPLAINED HEADACHE
• GLAUCOMA IN OTHER EYE
• PREVIOUS RETINAL DETACHMENT
• H/O OCULAR TRAUMA
  

SUSPECTED OR ESTABLISHED GLAUCOMA

1. OPTIC NERVE HEAD CHANGE OR NERVE FIBER LAYER DEFECT
2. VISUAL FIELD DEFECT
3. RAISED INTRAOCULAR PRESSURE

WHEN ONE OF THE THREE IS SEEN THEN GLAUCOMA IS SUSPECTED.
WHEN ANY OF THE TWO ARE SEEN THEN GLAUCOMA IS ESTABLISHED.

NORMAL GROUP

• INTRA OCULAR PRESSURE <21 mmHg
• NO VISUAL FIELD CHANGE
• NO OPTIC NERVE HEAD OR RETINAL NERVE FIBER LAYER CHANGES SUGGESTIVE OF GLAUCOMA
• NO INTRA- OCULAR DISEASE OR INTRA OCULAR SURGERY
• NO H/O HYPERTENSION, DIABETES.
• NO FAMILY HISTROY OF GLAUCOMA.

AAO VOLUME 109,NUMBER 3,MARCH 2002

The Eye Care America Glaucoma Project

Is your patient or their family at Risk for Glaucoma? Score below to see.

To Score: Add one score in each of the above categories. If you have a total score 4 or higher, you have a high risk for having Glaucoma.

GREATER RISK OF GLAUCOMA

• OLDER THAN 45 YEARS
• A FAMILY HISTROY OF GLAUCOMA
• HIGH INTRAOCULAR PRESSURE
• DIABETES
• MYOPIA
• USED STEROIDS FOR LONG TIME
• HAD A PREVIOUS EYE INJURY
  
  

Risk Factors

Now CCT

• Family History
• Older Age
• Race
  
  

THRESHOLD

THRESHOLD IS THE CRUCIAL CONCEPT IN PERIMETRY

Threshold is the dimmest stimulus seen by the a subject,50% of the time. Measured in decibels(dB) in automated perimetry. Higher the dB minimum is the light, lower the dB (0dB) brightest is the light.


0dB=Brightest light
40dB=Dimmest light

The Threshold of Sensitivity

The threshold is the crucial concept in perimetry. The threshold is the dimmest Light seen by a subject, 50% of the time.

• The threshold is not a distinct borderline. It is a transition region from seeing to not seeing like the transition from daylight to darkness.
  
  

NORMAL THRESHOLD VALUES

First four paracentral points are 3 º from vertical & horizontal lines,12.7 º from the fixation point & next all stimulus points are 6 degree apart.

Maximum threshold is at the fovea say,35dB dimmest light, with each degree to periphery threshold decreases by .03 dB.

STRATEGY/METHOD/TECHNIQUE HUMPHREY HAS MANY OPTIONS

SITA STANDARD= FULL THRESHOLD Normal 5-8 Min SITA FAST= FASTPAC Normal 3-5 Min Printout Single field analysis Over view STRATEGIES ARE FULL THRESHOLD 1983 20-30 Min FASTPAC 1991 14-20 Min SITA 1997 Swedish Interactive Threshold Algorithm 5-8 Min

SITA

• SWEDISH INTERACTIVE THRESHOLD ALGORITHM
• From MALMO UNIVERSITY OF SWEDEN 1997
• Developed by Anders Heijl & Boel Bengtsson and group over 10yrs period.
• New test Algorithm (a set of rules or procedures that must be followed in solving a particular problem)
• Beginning of test estimates based on normative data.
• Testing based on a model of “estimates” of normal and glaucomatous fields.
• SITA knows when to quit, it computes when to stop at each test location. SITA compares with a Senior Professor. Spends more time when unsure of the result and spends less time when with consistent result.
• SITA is time saving but results are equivalent to FULL THRESHOLD(SS) or FASTPAC(SF). Calculations are done after the test, so there is less fatigue for the patient.
• There are two types of SITA STANDATD(SS) or SITA FAST(SF) like, TOP (Tendency oriented perimetry of OCTOPUS)
  
  

SITA STANDARD 24-2

• IS
• SIMPLE
• SHORT
• SUPER
• SOUND
• SOLID
• SCIENTIFIC
• SINGLE FIELD ANALYSIS
• SMART
• SENIOR PROFESSOR
• BOTH FOR GLAUCOMA & NEUROLOGY
• USED ALL MOST ALL OVER THE WORLD
  
  

SO USING FASTER STRATEGIES

• SHORT TEST PROCEDURES :-

Reduce the fatigue effect caused by both

1. Retinal fatigue
2. Physical fatigue

Therefore a quicker test can be more reliable and accurate compare to testing with longer elaborate test strategies.

Types of Glaucomatous field loss

• First field loss was described by Albrecht von Graefe in 1856
• A decade later, he demonstrated preservation of the temporal and central regions in advanced glaucoma.
• Later,Bjerrum(1889) & Ronne(1909) demonstrated the presence of arcuate field defects, and nasal steps.
• The very large study by Aulhorn and Harms in 1967 demonstrated the importance of paracentral defects as an early sign of glaucoma.
  
  

Aulhorn's & Harms' classification of glaucomatous field loss

• Isolated paracentral scotomas
• Bjerrum's scotoma
• Bjerrum's scotoma breaking through to the periphery
• Central or temporal island
• Blindness
  
  

THE KEY PATTERN DEVIATION PLOT CHART

Scotomas are seen in the Suspected & Expected zones

LOOK ONLY LOWER RIGHT DEVIATION PLOT CHART

SINGLE FIELD ANALYSIS

SINGLE FIELD ANALYSIS

Name,ID ,DOB,R/L, pupil size& age. Next is SIX IN ONE Upper left Parameters, Stimulus size, back ground 31.5 dB, Catch trial Pupil dia, V.A. Near Correction, Date, Time, Age Upper right GRAY SCALE Upper left next to Gray scale is NUMERIC DATA, this is the raw data printed in numbers that express the patient's response in dB. A. This segment is expressed numerically and probability Plots (5B) of abnormality demonstrates how the patient's responses deviated from known normal patients of their age. Middle left (5A) aged matched Numeric data. lower left aged matched probability plot (5B) A.PATTERN DEVIATION : This is the KEY PLOT. The pattern deviation fine tune and enhance the total deviation data. It corrects total deviation from any media opacity (cataract), miotic pupil. It also displayed as both a numeric (6A) difference and with probability analysis Plots(6B).Any real localized defect is seen in this plot. Middle right Numeric data & Lower right( 6B ) probability Plot chart (Actual picture of the patient)

EVALUTING OF A SINGLE FIEL

KEY POINTS

• Combined evaluation of Optic disc & Visual field
• The defect should be reproducible, in particular peripheral defects in the first visual field should be confirmed before accepted.
• The shape of the field defect should correspond to retinal nerve fiber anatomy.
• The defect should correspond to changes at the optic disc.
• Diffuse loss is more likely to be due to cataract or more miotic therapy in glaucoma.

PATTERN DEVIATION PLOT CHART

IF YOU CAN ONLY READ THE PATTERN DEVIATION PROBABILITY PLOT CHART 6B THATS ALL.
OF COURSE IT MUST CORRELATES WITH THE DISC

Time : If it exceeds its normal then it's likely to be a Path. VF SS 5-8 Min SF 3-5 Min

UPPER LEFT

Fixation Monitor/Gaze Blind Spot: On the upper left side of the printout. Patient's eye is monitored by fixing the eye towards a yellow light. At the beginning of the test after fixation 5% of the supra threshold a type of stimulus is given on the B.S. to find out central fixation. This is called HEIJL-KRAKOW method. Here fixation target is central. If there is any macular pathology instead of central fixation we choose small diamond or large diamond just below the central fixation. (See Slide 31).

FL is a tricky thing. It should be within 20%,but it will be a reliable VF with high FL, but low FP & FN.

FP TRIGGER HAPPY it should be below 10%.It means that the pt. pressed the switch without seeing the light.

FN First a low intensity light is seen. At the same point a brighter stimulation (more than 9dB) is given to see if Pt. is alert or not. Its normal value is 15%but in Path. Condition it goes up above normal level.

INSIDE HUMPHREY PERIMETER

A lesion in the retina is twenty times magnified in the bowl Optic nerve is 1.5mmx20=30mm which seen in reduced form.

RELIABILITY PARAMETERS

UPPER RIGHT GRAY SCALE

This is a “HOLISTIC” overview on the displays the patient's responses in various shades of grey instead of printing numeric data. It is of little clinical value. In octopus it is colored. From gray scale it is hard to pick out THE WHEAT from Chaff.

SEARCHING FOR A
NEEDLE IN HAY
STACK

A GLANCE GUESS FROM GRAY SCALE

ONLY GROSS DEFECT

This young lady of 23 is an established case of RP. Her both discs are pale with jet black spots in the peripheral retina, parents were cousins, sister and brother, H/O night blindness,V.A.6/6 with very good FT 37 dB, D/D 1.R.P 2.lens rim defect 3.Retinoschisis 4.Pan retinal photo coag 5Peripheral retinal degeneration 6C.R.O ..7.Aphakic glass.

GRAY SCALE

TYPES OF SCOTOMAS

CREENING TEST

SCREENING PROGRAMS HFA II

SCREENING FOR GLAUCOMA MAJOR POINTS

• No single good screening tool for Glaucoma exist.
• Tonometry suffers from a poor balance between sensitivity and specificity.
• Optic nerve head examination requires skilled observers and does not have a defined end point.
• Perimetry is expensive, and has a learning curve.

NAME DOB ID

V.A 6/6 B/E IOP Normal C;D Rt. .4 Lt. .6 Plan Repeat VF

By mistake her DOB was given 1969, instead of 1959.Gray scale shows slight Deep GHT GRS. But when her exact DOB is given 1959,GHT is WNL. So, always give Correct DOB as well as last corrected distance vision.

BUT THIS IS A HIGHLY SUSPECTED FIELD.

PUPIL SIZE 3 TO 7 mm

	One EYED established POAG ON Anti Glaucoma Drug First field done 2.1 2 nd VF 3.9 mm pupil

All fields should be done with normal reacting pupil within 3-7 mm in size. Dilated pupil gives less false result than the small pupil. So, please check pupil size before seeing a Visual field (VF) Humprey's latest version 12.3 will give you the pupil size on the screen before starting the field.

PUPIL SIZE

• AREA OF CIRCLE = x r²
• 2mm Pupil Area=3.14 x 1 mm²=1 mm²
• 8mm Pupil Area=3.14 x 4 mm²=16 mm²
• SO,IF YOU SHIFT PUPIL FROM 2mm TO 8mm, YOU WILL GET AN INCREASE OF 16 FOLD AREA OF THE PUPIL SIZE
• SO,WIDE VARIATION OF THE PUPIL SIZE WILL GIVE YOU A FALSE VISUAL FIELD DEFECT, SO PUPIL SIZE SHOULD BE BETWEEN 3 mm TO 7 mm AND IT SHOULD REACT TO LIGHT ON PUPIL .

GHT & PROBABILITY

<5% = Significant <0.5% = More Sig. IN THE LOWER MIDDLE

GHT- This test assumes that glaucoma does not cause a generalized Global depression of the field of vision. It takes advantage of the asymmetric field loss pattern generally seen in glaucoma. The test analyses defects in the superior hemi field and makes comparison with mirror image locations in the inferior hemi field.

1. GHT may be OUT SIDE NORMAL LIMIT (ONL)
2. BORDER LINE (BL)
3. GENERAL REDUCTION OF SENSITIVITY (GRS)
4. ABNORMALLY HIGH SENSITIVITY
5. WITH IN NORMAL LIMIT (w.N.L)

GHT

The GHT has been evaluated by both Peter Åsman and Heijl(1992) and by Katz(1996). IT WILL GIVE YOU FIVE RESULTS.

1. Abnormally high sensitivity. The general height of the field is beyond the 99.5% limit for normal.
2. Out side normal limits (ONL) - The asymmetry is beyond the 99% limit for normal in any of sector pairs. If seen twice in two consecutive fields early glaucomatous defect criteria by “Anderson”.
3. Borderline (BL) - The asymmetry is beyond the 97% limit for normal in sector pairs. It's not a pathological field.
4. General reduction in sensitivity (GRS) - The general height is below the 0.5% limit for normal. Seen in Cataract, High Myopia, Media opacity, Dilated pupil.
5. Within normal limits (WNL) - When none of the above four criteria are seen.

GAZE TRACKER

By seeing this tracing at lower end of the field you can judge whether the fixation is OK or not.

		SEEN JUST BELOW THE GRAY SCALE GLOBAL INDICES MD (Mean deviation) Or mean defect- The mean deviation is the average difference between the patient's overall sensitivity and that of age matched controls. High MD seen in case of Normal: Cataract Miosis Ref.error Fatigue Then PSD will be normal.
AT THE BOTTOM OF THE FIELD		PSD: Is an index of unevenness in amount of field calculated from Pattern deviation Plot chart. (Normal up to 2.5)

INTERPRETATION CRITERIA INTERPRETATION CRITERIA

• THE REASON FOR DOING FIELD.
• CORRECT DATA AND RELIABLE FIELD.
• PUPIL SIZE n PATIENT'S PERFORMANCE
• READ CHART WITH OTHER FINDINGS
• DIAGNOSE THE CASE, IF IN DOUBT REPEAT THE SAME TEST BUT NOT THE SAME DAY
• INTERPRETATION OF A FIELD IS NOT A CHILD'S PLAY

AN EARLY FIELD DEFECT ACCORDING TO “ANDERSON ”

Cluster of 3 or more adjacent points in an expected, suspected location (Typical for glaucoma) of central 24 degree field. ON AT LEAST TWO CONSECUTIVE FIELDS
OR
Glaucoma Hemi field test (GHT) Outside normal for at least two consecutive Fields
OR

LEARNING CURVE

First field is not always a reliable field (of course not all the time). She is a young school teacher. First VF done after seeing her IOP R30 &17 L. healthy NRR .6 & .5 are the cup : disc ratio R/L respectively. Since 5 th June '00 she was on anti- Glaucoma drug. We stopped her drops after Seeing the 2 nd field .On the 3 rd field on 29 th Oct '01 her VF is within Normal limit & IOP too. It's a long term fluctuation.

First field is not always reliable

Field done out side BANGLADESH

This young girl of 10yrs.has been dig. in Marfan Sy with NTG.It can not occur before 45yrs.Diag. Out side BD.In Dhaka It has been dig. Marfan Without Glaucoma her first field is not reliable. Second field done at Dhaka is OK GHT ONL is due to high myopic cylinder. Doing field is like a Baby sitter. Glaucoma may be associated with sublaxation of the lens. Here her IOP is normal Her both NRR are healthy.

I LOVE MY COUNTRY

BEFORE SENDING THE PATIENT

1. GIVE LAST CORRECTED DISTANCE VISION
2. DETAIL OF OPTIC NERVE EXAMINATION IF POSSIBLE WITH DIAGRAM
3. INTRA OCULAR PRESSURE (IOP) FLEXIBILITY IS THE ENEMY OF STANDARDIZATION

A LABORIOUS THRESHOLD TEST HIGH RESOLUTION PATTERN MAY FERRET OUT EARLY SIGNS OF GLAUCOMA.BUT IT MAY ALSO GENERATE ARTIFACTS, IF THE PATIENT'S ENDURANCE IS STRESSED BEYOND 20 MINUTES PER EYE “LEADERSHIP IS LIKE SWIMMING CANNOT BE LEARNED IN A “DAY” OFTEN TO GET A RELIABLE FIELD YOU HAVE TO DO ONE FIELD EACH MONTH FOR THREE CONSECUTIVE MONTHS OF COURSE NOT ALL THE TIME. PLEASE TELL YOUR PATIENT THAT IT IS A TIME CONSUMING TEST.TELL HIM OR HER TO TRY TO COME IN THE MORNING. IT'S A PSYCOPHYSICAL TEST.TELL THEM NOT TO BE IN HURRY.HE OR SHE MAY MISS THE BUS, WITH AN UNRELIABLE FIELD.

It will be like a game, very easy to do !!

COMMON PROBLEMS WITH PERIMETRY

• LEARNING / FATIGUE EFFECTS
• PUPIL SIZE
• REFRACTIVE ERROR
• ARTIFACTS
• PATIENT COOPERATION

REPORT

PHYSIOLOGICAL FUNDUS

She is a young lady of 27yrs. old. Her IOP are normal. But big C;D .65 B/E, her Doctor put her anti Glaucoma drop. But her fundus NRR is healthy & ISNT rule is ok. Her two consecutive fields are normal as well her B/Y field are O.K It's a normal PHYSIOLOGICAL DISC

NORMAL TENSION GLAUCOMA

A CONDITION IN WHICH GLAUCOMATOUS CUPPING OF OPTIC NERVE HEAD, LOSS OF NERVE FIBER LAYER AND VISUAL FIELD LOSS OCCURS AT AN IOP BELOW <21mmHg MEASURED AT DIFFERENT TIMES, WITH OPEN AND NORMAL APPEARING ANGLE .

VARIENTS OF NTG

• NON-PROGRESSIVE FORM
• PROGRESSIVE FORM

OPTIC NERVE HEAD CHANGES IN NTG

• Large cupping disproportionate to field loss
• Sloping edges
• Thinning of NRR especially inferiorly & Inf.temp
• Hourglass pattern of lamina cribrosa
• High incidence of acquired pit of the Optic head
• Greater frequency & extent of Peripaillary atrophy
• Higher incidence of splinter hemorrhage of OND
• More localized nerve fiber layer defect

VISUAL FIELD DEFECT

• Localized, deep, steep defects
• Close to fixation

OTHER ASSOCIATES OF NTG

• NTG usually seen in elderly F>M 6:1
• More common in ASIANS
• F/H ,Myopia, Systemic hypotension, hypertension, Postural hypotension, Nocturnal hypotension, Cardiovascular disease, Migraine, Raynaud's , Acute blood loss, Hypovolemia following severe vomiting & diarrhea

Differential Diagnosis of NTG

• POAG with a wide diurnal fluctuations
• Pigmentary glaucoma
• Intermittent IOP elevation as in, glaucomatocyclitic crisis and intermittent angle closure
• Previous episode of IOP elevation: Steroid induced Glaucoma
• Non-Glaucomatous optic nerve disease like ischemic optic neuropathy, Congenital optic disc pit, compressive lesions of optic nerve etc.

DIAGNOSIS of NTG

OCULAR EVALUTION ;

Apart from routine ocular & FUNDUS examination.
LOOK FOR

1. Central corneal thickness(520 µM) , thin cornea may give false low IOP reading, POAG might appear as NTG
2. Record of a diurnal curve
3. Perimetry
4. HRT
5. Record of ocular blood flow

MEDICAL EVALUTION

1. Cardiovascular examination including 24 hrs. BP monitoring to rule out nocturnal hypotension, Carotid artery Doppler imaging to assess blood flow, capillary filling time on exposure to cold.
2. Complete blood picture, ESR, Blood profile, Lipid profile to ruled out Hypercholesterolemia
3. MRI to ruled out Diffuse cerebral ischemia

MANAGEMENT OF NTG

Goal of treatment is to preserve the visual FUNCTION

Non-Progressive form does not require any treatment, as it rarely progresses. Monitoring & follow up is required every 6-12 months.

Progressive form needs treatment. Target should be to reduce 30% IOP from the initial, may delay the progression.

NTG

• A GARDEN VARIETY OF POAG (30% out of 66%)
• MOST LIKELY GENETIC (OPTINEUON GENE)
• A BENIGN VARIETY OF POAG
• BUT DIFFICULT TO TREAT IOP TO BE REDUCED BY 30%
• BLINDNESS IS UNUSUAL IN NTG
• F>M 6:1
• PATIENTS ARE HYPOTENSIVE
• LOCALIZED VFD & FIXATION THREATENING
• Age must be above 45years & F/H
• IT IS EASY TO MAKE IOP 4OmmHG TO 20mmHG BUT TOUGH TO BRING IOP 16mmHG TO 14 mmHG

TREATMENT

• Avoid beta blockers; non selective Beta-blockers may decrease the perfusion pressure. But selective blockers like Betaxolol may increase OBF but at the same time it has less IOP lowering.
• Brimonidine (Alphagan)
• Calcium channel blocker of systemic use Nifedipine is benificial
• Prostaglandin
• ALT
• Surgery

PROGRESSION OF NTG

• Deepening of existing field defect
• Expansion of existing field defect
• Appearance of new defect
• Threat to fixation

PLAN OF TREATING LTG

1. VERY DIFFICULT TO TREAT AS WELL AS TO DIAGNOSE
2. FIRSTLY, TO REDUCE THE IOP BY 30%. HER IOP WAS 15 WE REDUCED HER IOP TO 15X.7=10.5MmmHg WITH AZOPT
3. IF HER IOP BECOMES BELOW 10 THERE IS NO NEED OF DOING Visual Field
4. THINK BEFORE USING BETA BLOCKER DROPS IN NTG
5. PHASING TO BE DONE
6. If medical treatment fails then ALT has to be tried, if it also fails go for Surgery
7. 24 Hrs. MONITORING OF B.P. IF DIAS DIPS DOWN AT NIGHT BELOW 60 mmHG AND PT IS HYPERTENTSIVE AND IF HE/SHE IS ON BETA BLOCKER TYPE OF DRUGS THEN THAT SHOULD BE CHANGED.CONSULT WITH CARDIOLOGIST IOP/BP
8. Neuro protector Vit E. Aspirin, aerobic exercise, anti oxidant can be used to improve perfusion. TRY TO CORRECT HYPOTENSION.
9. What to do when there is High BP with Glaucoma? TOUGH QUESTION.?
10. Three U.S. President died of hypertension. Theodore Roosevelt, Woodrow Wilson and Franklin Roosevelt, all died from Complication from FLUCTUATION OF HYPERTENSION

HIGHER RISK OF PROGRESSION NTG

• IOP near the upper limit of normal
• Wider diurnal variation
• Deep localized notch of the disc
• New optic disc hemorrhage
• Systemic hypotension
• Young age
• Black race
• Myopia
• Vasopasam
• No history of hemodynamic crisis (Hemodynamic episode is associated with non-progressive form)

COMMON IN NTG

NTG PATIENT'S VF AND FUNDUS

Both the overviews show NTG R>L .Both Discs have V>H and Sup & Inf Notching are seen.

AN ESTABLISHED CASE OF NTG.HER IOP IS NOW 10mmHg B/E

LAST PT'S 24 MONITORING OF BP

24 hrs. Monitoring of a LTG pt. done with mild hypertension. She is on Atenolol 50mg in the morning Amlodipine 5mg at bed time. After she has been diagnosed as NTG on Jan 02 and on Azopt thrice daily. During Night her diastole drops below 60.She has been advised to consult her cardiologist about her low diastole tendency at late Night.

COLOR DOPPLER SONOGRAPHY

HEALTHY............ .......GLAUCOMA PATIENT

Color doppler, sonography, is used on Glaucoma patients to determine the blood velocity in several vessels leading to the eye. This enables a calculation of resistance index, a parameter for downstream resistance to flow that is of particular Importance in glaucoma. Here an ophthalmic artery of a healthy individual and the same test on Glaucoma pt. with reduced perfusion is shown.

OVER VIEW

This middle aged man complains of frequent Change of his reading glass. IOP normal. B/E. V.A 6/6 B/E. With +78 deep cupping has been noticed. B/E.ISNT rule is not ok. Rt. sup NRR is thinner than nasal NRR. In Rt. Fundus both Sup & inf. NFLD are seen which well correlates with the VFD Sup & inf arcuate SCOTOMAS. So, the second Rt. field is reliable and taken as base line VF and an early case of NTG. Lt. Fundus shows inf. temp. NFLD as well as inf. notching, which well correlates with VF's Supra Nasal arcuate SCOTOMA joins the upper nasal step. Lt. temp. pallor of the disc well correlates with the Upper Nasal step. SO BOTH THE SECOND FIELDS ARE RELIABLE & TAKEN AS A BASE LINE FIELD AND WELL CORRELATES WITH THE FUNDUS, A CASE OF EARLY NTG.

WHY 21 CONSIDERED “NORMAL”

THE IOP IS DISTRIBUTED IN THE NORMAL POPULATION IN A GAUSSIAN OR “BELL-SHAPED” MANNER

DUANE'S CD-ROM 2003 EDITION

TARGET PRESSURE RANGES; Goal for lowering IOP

A target pressure will not damage the optic nerve any further.

TARGET IOP

		TARGET
	IOP, Slight disc damage	17-18mmHg
	IOP, moderate disc damage	15 mmHg
	IOP, Serious disc damage	12 mmHg

Slight damaged mean a change in the optic nerve ± small VFD

Dr. Rick Wilson

Establishing Initial Target IOP (CIGTS Study)

Target IOP = (1 - Reference IOP + Visual Field Score ) x Reference IOP 100

Example

MODE OF ACTION

.	IOP Decrease	Decreases Aqueous Production	Increases Uveoscleral Outflow	Increases Trabecular Outflow
Brimonidine	20%-30%			.
ß-Blockers	20%-30%		.	.
Pilocarpine	10%-20%	.	.
Dorzolamide	15%-20%		.	.
Prostaglandin	25%-30%	.		.

DISEASE CAPSULE ; POAG

1. EPIDEMIOLOGY

• Major Risk Factors
• Advanced age
• Black race
• Positive F/H
• Elevated intraocular pressure

2. MINOR RISK FACTORS

• Diabetes mellitus
• Myopia

3. SYMPTOMS

• Early; none
• Late; loss of peripheral vision
• Very late; loss of central vision

4.SIGNS

• Cornea.............................Normal
• Anterior Chamber............ Normal
• Iris................................... Normal