Page 72 - NAME OF CONDITION: REFRACTIVE ERRORS

photocoagulation, is used for the treatment of proliferative diabetic retinopathy. It

may be done in more than one session. Focal and grid photocoagulation are used for
the treatment of diabetic macular edema.

DIABETIC MACULOPATHY:
Argon laser photocoagulation:
Indications:
 All eyes with CSMO should be considered for laser photocoagulation
irrespective of the level of visual acuity because treatment reduces the risk
of visual loss by 50%.

 Pre-treatment FFA is useful to delineate the area of leakage and to detect
ischaemic maculopathy which carries a poor prognosis.

Focal treatment – burns are applied to microaneurysms and microvascular lesions
in the centre of rings of hard exudates located 500 -3000µm from the centre of
macula .The spot size is 50 - 100 µm , exposure time 0.1 sec with sufficient power to
obtain gentle whitening or darkening of the lesions.
Grid treatment – burns are applied to areas of diffuse retinal thickening more than

500 µm from the centre of the macula and 500 µm from the temporal margin of the
optic disc.the spot size is 100 µm and exposure time is 0.1 sec giving a very light
intensity burn.

PROLIFERATIVE DIABETIC RETINOPATHY:
Panretinal photocoagulation:

Laser treatment is aimed at inducing involution of new vessels and preventing visual loss.

Indications:
 PDR with HRCs
 Neovascularisation of irirs
 Severe NPDR associated with :

o Poor compliance for follow up
o Before cataract surgery/YAG capsulotomy
o Renal failure
o Pregnancy
o One-eyed patient
The recommended therapy is 1200-2000 burns 500µm in diameter delivered through
the goldmann lens or the same number of 200 µm burns delivered through volk lens.
The burns should be intense enough to whiten the overlying retina,which usually
requires a power of 200 – 600mW and duration of 0.1 second.

72