الفهرس 
Materials and methodsOnly 14 pages are availabe for public view
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Abstract
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Argon laser iridectomy has become a widely accepted highly successful
procedure in the treatment of angle-closure glaucoma It has been found to be safe
and effective. It is easily and conveniently performed on an out-patient basis.
Now, it can replace the surgical iridectomy in relieving pupillary block.
In this study, we reviewed the literature about the anatomy of the iris and
anatomy of the angle of the anterior chamber. We reviewed also, the
pathophysiology of the primary angle-closure glaucoma. We lined out the laser
biophysics, the argon laser system and effects of laser on ocular tissues.
Laser peripheral iridectomy has also been discussed : its aim, indications,
contraindications, advantages, disadvantages, different techniques and
complications.
Our aim in this study was to evaluate the argon laser in performing peripherl
iridectomy in cases of primary narrow angle glaucoma and to evaluate different
techniques used in performing laser peripheral iridectomy.
50 eyes of 38 patients having primary narrow angle glaucoma were included
in this study. They were subjected to argon laser peripheral iridectomy.
We had? eyes with history of acute attack (s). 18 eyes with chronic angleclosure
glaucoma and 29 eyes either fellow eyes or eyes with narrow occuldable
angles.
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Considering the intraocular pressure control, our success rate was 98% with
a mean DROP of 7.16 mmHg which is statistically significant
18 eyes were perforated by the drum head technique and 31 eyes were
perforated by the chipping away technique. We found that, with the drum head
techique, we needed less laser power. less number of shots and ’Consequently less
energy although, we needed a mean sessions more than with the chipping away
technique.
It was found that with Abraham lens, we needed less laser power, less
number of shots, less energy and less number of sessions.
Perforation in a crypt was found to be insignificantly different from
perforation outside crypt. But, the number of shots used for penetration was less
(although statistically non significant) inside a crypt than outside.
The encountered complications were few manageable short term
complications. They were pupillary distonion (30%), closure or narrowing of the
iridectomy hole requiring reopening (14%) localized lens burns (10%) and corneal
burns (2%).The most difficult complication was the failure to penetrate the iris.
CONCLUSION
We can conclude that argon laser has the ability to create patent iridectomies
in an out-patient sittting. When it is used as an initial procedure in the treatment of
angle closure glaucoma, patients are not exposed to the potential complications
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associated with surgery. There is also, a reasonable chance that the simple
procedure will succeed.
The light brown irides were the easiest to perforate. The post-lasrer spikes of
elevated intraocular pressure can be prevented by routine prescription of carbonic
anhydrase inhibitor (Diamox) immediately post-laser and for 24 hours.
Closure of the iridectomy hole was not noted in any treated eye if the
iridectomy was patent for three months. The lenticular opacities due to laser bums
did not progress during the follow up.
The use of the Abraham lens is a favor. It was found to fix the eye (with no
need for retrobulbar infilteration even with uncooperative patient), magnify the
perforation site with no effect on the depth of focus and to cause the laser beam to
converge sharply with a reduction in the spot size focused on the iris. Thus
increasing the power density on the iris. It also leads to increase the relative
divergence of light at the cornea resulting in decrease of the power density at the
comeallevel.
An important factor to minimize the shots needed, is to superimpose each
shot exactly onto the preceeded one. Another factor to minimize the number of
shots. is to use the optimum power. Overheating leads to charcolization and underheating
leads to ineffectiveness.
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Post-laser iritis can be calmed down by the routine use of post laser topical
corticosteroid at least four timely a day for at least three days.
Lastly, we can say that laser peripheral iridectomy is a suitable procedure to
be tried as an intial manouver for all cases of primary angle-closure glaucoma with
pupillary block.