DIABETIC MACULAR EDEMA The more common cause of visual loss (10 times as much as PDR) Occurs in about 1/3 of diabetics usually after 8 - 10 years

1. THE RATIONALE AND TECHNIQUE
OF LASER TREATMENT OF DIAB.
RET.
UNACCEPTABLE
MISMANAGEMENT
By
A-L SIAM

2. DIABETIC MACULAR EDEMA
 The more common cause of visual
loss (10 times as much as PDR)
 Occurs in about 1/3 of diabetics
usually after 8 - 10 years

3. DIABETIC MACULOPATHY
1. Focal leakage maculopathy : leaky nests of microaneurysms,
accumulation of serous and/or lipid exudates , ischemic foci.
Best potential for treatment response.
2. Diffuse leakage maculopathy : throughout the post. pole &
diffuse fluorescein leakage and cystoid edema of the macula.
Ischemic foci larger and more numerous, breach of the perifoveal
capillary network. Proper photocoagulation  partial restoration
of macular structure & function
3. Cystoid maculopathy : large intraretinal cysts in the macula,
diffuse fluorescein leakage in early stages and later pooling of the
dye - flower petal appearance. Visual acuity greatly diminished.
No potential for structural or functional improvement
4. Ischemic maculopathy : macular capillary or arteriolar
nonperfusion worst prognosis
A. Intraretinal Maculopathy with N/P Diabetic Retinopathy:

4. 1. Internal limiting membrane folds
2. Premacular fibroglial membrane
3. Thickened and adherent posterior hyaloid : Cellophane
membrane over the macula often with premacular
hematoma,
4. Heterotopia of the macula
5. Lamellar macular hole
6. Macular detachment
All can not be treated neither with laser nor with antiVEGF
B. Preretinal Maculopathy with PDR as a result of
vitreous modification and anomalous posterior
vitreous detachment :

5. FAZ
0.5
Macula
1500 m
Perifoveal Capillary
FAZ : The FAZ normally varies
between 0.33 mm to 0.50 mm
Increases significantly in all
stages of DR and increases
with progress of DR
PCN : The integrity of the perifoveal capillary network is of prognostic
significance in eyes with DR
Network (PCN )

6. mmm
FAZ = 330 - 500 m
1500 FOVEA (Macula)
PCN
FAZ : Foveal Avascular Zone
PCN : Perifoveal Capillary Network
The FAZ increases significantly in all stages of DR & increases with progress of DR
 PCN : each sector supplied by several terminal arteriole , occlusion of a single
terminal arteriole will not produce circulatory arrest in the corresponding area
The integrity of the PCN is of prognostic significance
Xanthophyll : a yellow pigment in the inner retinal layer of the macula (1.5 mm in
diameter) or 1 DD. Strongly absorbs blue laser light. Use of blue laser light inside
the FAZ and FOVEA is dangerous
MACULAR
LANDMARKS

7. Focal Maculopathy, Evaluation & Prognosis

8. Focal Maculopathy
PCN
FAZ

9. Interruption of PCN & ischemic foci
PCN ( Perifoveal capillary network )
Capillary drop out

10. Diffuse Macular Edema
Broken PCN (Perifoveal Capillary Network)
PCN PCN

11. DIFFUSE MACULAR
EDEMA
 The edema is characterized by diffuse leakage from
extensive areas of the posterior retinal capillary
bed, scarcity of hard exudates and cystoid spaces
 Eyes with diffuse macular
edema carry a particularly
poor prognosis

12. Ischemic maculopathy : macular capillary or arteriolar
nonperfusion worst prognosis

13. LASER TREATMENT OF DIABETIC
MACULAR EDEMA
FFA is generally used during PC to identify treatable lesions
Grid :
 100 m spot size , duration 20- 50 -100 msec.
 light to moderate intensity
 Space between shots one burn wide
 Can place on papillo-macular bundle in edematous macula
 Not closer than 500 m from centre of fovea
 Supplement if mac. edema persists three months after treatment,
but not closer than 250 m from the centre of the fovea
 Repeat FFA and OCT

14. FAZ = 330 - 500 m
1500u FOVEA
PCN
Warning
Heavy burns ,close to the fovea paracentral scotoma ,especially with longer
exposure
Grid & Modified
Grid
1500 m
Parameters : spot size 100m , duration 50-100 ms or shorter
(20ms) with PASCAL, and modern lasers & barely visible
reaction ,with less collateral damage.

15. MACULAR TREATMENT IN DIABETIC
RETINOPATHY
 For focal treatment always use yellowish - green at 532 nm
(diode-pumped frequency doubled Nd. YAG laser)
 The target is the leaking vascular abnormalities
 Very light burns of 100 m spot size of short duration (20 - 50 ms)

17. Before treatment

18. After treatment – needs retreatment

19. After retreatment , dry macula

20. Diabetic Maculopathy
Prognosis
 Initially low visual acuity (<6/60)
 Diffuse origin of macular edema
 Central cystoid spaces
 Foveal exudate
 Foveal hge
 Marked destruction of foveal arcade ( PCN )
Factors Unfavourably Affecting Diab. Maculopathy :

21. Laser photocoagulation is the mainstay of, treatment for
clinically significant macular edema associated with diabetic
retinopathy , as has been shown in landmark studies, such as the
Diabetic Retinopathy Study ,the Early Treatment Diabetic
Retinopathy Study (ETDRS).
Shortening exposure time to 20-50 ms is significantly less painful
but equally effective as conventional parameters

22. Argon gas laser 1976
Blue –Green
488 &512 nm

23. 532nm – Yellowish green
Diode-pumped, Frequency- doubled , Nd: YAG laser
2001
VIRIDIS

25. Laser Retinal Spot Size Multiplier in Emmetropic Eye
Type of Lens: Multiplication Factor for
spot size:
Three mirror Goldmann type 1.08
Mainster 1.05
Area Centralis 1.01
Mainster wide-angle 1.47
Panfundoscope 1.41
QuadrAspheric or Super Quad 1.92

26. WHAT IS ADEQUATE LASER
TREATMENT?
Sufficient quantity of laser impacts according to the severity of the
retinopathy :
In non proliferative diabetic retinopathy
- Extent of leak
- Extent ischemia
- Degree of macular edema (OCT)
In proliferative diabetic retinopathy
- Extent and place of new vessels
- Presence of vitreous hemorrhage
- Rubeosis iridis
Technique
Wide scatter or PRP
One or more sessions
Associated with intra-vitreal Triamcinolone Acetonide or AntiVEGF

27. PRP for PDR
2000-burn 200-300 spot sizes PRP would be required in
a single session to regress PDR as in high risk cases.
( The application of 1500 – 2000 shots, 100 ms PRP burns in a
single session was shown to be a safe regimen.
A higher number of laser burns is required to prevent visual loss in high risk
cases : ( neovascularization within 1 disc diameter of the optic disc; NVD greater
than 1/3 disc area or NVE greater than half a disc area; and preretinal or
vitreous hemorrhage).

28. PRP plus grid for macular edema

29. Deceptive colour picture

30. Deceptive Colour Picture
Severe Equatorial & Peripheral Ischemia

31. Complications of Laser
Photocoagulation
 Incorrect focus : corneal burns, lenticular burns.
 Excessive energy :
 Rupture of Bruch’s memb.  CNV later
 Disruption of major blood vessels vit. hge. (rare), vascular occ. (rare)
 Choroidal rupture  choroidal det., choroidal hge.
 Exacerbation of preexisting macular edema
 Treat macular edema in combination with PRP
 Intravit, anti VEGF or Triamcinolone Acetonide (Kenacort)

32. Short laser pulse duration of typically 20 ms as in
PASCAL and new machines
ie 5 times shorter than in conventional systems,
This provides less heat diffusion to the retina and choroid
i.e less collateral damage to surrounding tissue
and less pain,and more comfort
By rapid pulse delivery (interval 0.1 – 0.2 sec)
significant reduction in treatment time .
UPDATE OF LASER PHOTOCOAGULATION

33. 10 ms 100 ms
Short Pulse 10 ms 20 ms

34. Intravitreal Triamcinolone Acetonide or AntiVEGF
In conjunction with PRP as a comprehensive treatment & to reduce
the incidence of post PRP macular edema for PDR without
significant vitreous modification
Pars Plana Vitrectomy
TA-assisted ; with PVD only , or PVD with ILM peeling for 1- chronic
resistant macular edema in N/P Diab,Ret. And 2-for the
maculopathies associated with PDR due to vitreous modification
and anomalous posterior vitreous detachment

35. PATTERN SCAN LASER (PASCAL)
photocoagulation system,
In 2006, OptiMedica (Santa Clara, CA) introduced a new, “more efficient”
system for the delivery of laser light energy to the retina. This slit-lamp-
based laser, known as the Pattern Scan Laser (PASCAL) photocoagulation
system, allows the physician to apply a multiplicity of laser burns

36. PATTERN SCAN LASER (PASCAL)
photocoagulation system

37. Fluence : used to describe the energy delivered
per unit area, in which case it has units of J/m2.

39. 1. Improving O2 transfer from choroid through coagulated retina
2. Reestablishing blood-retinal barrier by inducing RPE
proliferation
3. Stimulation of pericyte proliferation
4. Ablating ischaemic retina (esp. in the periphery) and thereby
reducing the neovascular response (VEGF release)
5. Destruction of peripheral retina reduces the amount of VEGF
Rationale for Photocoagulation

40. 1- Reduced metabolic demand
2-debulking of diseased retina
3-Increased intraocular oxygen
tension
4- Altered production vasoactive cytokines
including VEGF
Rationale for Photocoagulation

41. Meyer Schwickerath, 1963
BENIFICIAL EFFECTS OF PHOTOCOAGULATION ON
DIAB. RETINOPATHY

42. Subvisible (Subthreshold) Diode
Micropulse Photocoagulation(SDM)
Shorter bursts of near infrared (NIR) radiation (810 nm) with small spot sizes (100–
200 µm) have also been applied for nondamaging retinal phototherapy. Termed
subvisible diode micropulse (SDM) photocoagulation. It uses the OcuLight SL
clinical system (Iridex Corporation, Mountain View, CA, USA).
Hyperthermia in this approach does not exceed the threshold of cell toxicity and
has a high degree of selectivity.
SDM allows for complete and confluent coverage of the entire diseased retina.
The 810 nm wavelength is selected due to its reduced absorption by
photoreceptors and hemoglobin, and thus more selective absorption by melanin in
RPE and pigmented choroid.
Typically, a sequence of micropulses of 100 μs in duration separated by 50-150 μs
is applied during 200 to 500 ms longer pulse envelopes

43. Upending more than a half-century of
universally held belief in the therapeutic
necessity of laser –induced retinal damage
Subvisible (Subthreshold) Diode
Micropulse Photocoagulation(SDM)

44. WHAT ARE THE EYES THAT YOU SHOULD
NOT TREAT
 A few microaneurysms
 A few exudates
 A little retinal thickening far from the centre of the fovea
Eyes with macular oedema which is not
clinically significant :

45. Horrible Malpractice

46. InadequateTreatment
No more Acceptable
Few shots !!
Several sessions ? ?
Not treating further toward the periphery !!
No proper treatment in the macular area ? ?

47. CONCLUSION
 Regular screening
 Careful follow-up
 Timely treatment
To prevent blindness from diabetic retinopathy :
By the time many eyes receive laser and injection
treatment for macular edema, visual loss already
has occurred, and can not be restored