1. Cheil Eye Hospital , Daegu, Korea
The Prognostic Factors of the Success of Laser Iridotomy for Acute Primary Angle Closure Glaucoma
Kyoo Won Lee, M.D. Ph.D.
Jong Wook Lee, M.D.
Jung Ho Lee, M.D.
Financial Disclosure：All authors declares no financial interests
Cheil Eye Hospital , Daegu, Korea

2. Purpose
To analyze the prognostic factors of the success of laser iridotomy for acute primary angle-closure (APAC) with initial intraocular pressure (IOP) over 40 mmHg/AT .

3. Materials & methods Maximum tolerable medical therapy
June ~ June 2008
baseline intraocular pressure over 40 mmHg/AT
retrospectively reviewed the medical records of 77 eyes of 77 patients
laser iridotomy was performed after maximum tolerable medical therapy (MTMT) for all the patients
Maximum tolerable medical therapy
- β-blocker eye-drop
- 2% pilocarpine eye-drop
- Oral Carbonic anhydrase inhibitor
- Intravenous Mannitol injection (if severe corneal edema was present)

4. Laser iridotomy Laser setting - using Abraham iridotomy lens
- 1% apraclonidine and 0.5% proparacaine HCl were dropped
before the laser iridotomy
- sequential combination (argon and Nd:YAG laser)
- 1% apraclonidine was dropped after the laser iridotomy
- use 0.1% Fluorometholone q.i.d. for postoperative 1 week
Laser setting
Argon laser
ND:YAG laser
Spot size
50μm -
Duration
0.05~0.1sec
Power
900~1000mW
2.3~3.4mJ
Count
10~70
3~25

5. The patients were divided into two groups
- success group : IOP was 20 mmHg or lower at postoperative one month
- failure group : IOP exceeded 20 mmHg at postoperative one month
Evaluation
(the success rate of the laser iridotomy according to)
- Sex distribution
- Age
- Baseline IOP
- Duration between acute glaucoma attack and hospital visit
- Response of maximum tolerable medical therapy
- Response of intravenous hyperosmotic agent (Mannitol®)

6. Results
Table 1. Comparison of sex distribution between the success group and the failure group after laser iridotomy
Sex
L I Success
L I Failure
Total
Odds ratio
95% confidence interval
Male 14 4 18
Female 47 12 59
1.119
(0.311~4.022)
Among 77 eyes (18 males and 59 females), there was no difference of the sex distribution between the success and the failure groups.
Table 2. Age distribution between the success and the failure group after laser iridotomy
Chi-square test
Age (year)
L I success
L I failure
Total
P value
≤60 19 3 22
0.331
61-70 9 31
>70 20 4 24
The average age was years old in the success group and years old in the failure group, showing no significant difference between the two groups.
There was no significant difference of the laser iridotomy success rate according to the patients’ age.

7. Table 3. The success rates according to the initial IOP
Chi-square test
IOP (mmHg)
L I success
L I failure
Total
P value
40-50 31 6 37
0.595
51-60 28 9
>60 2 1 3
When the patients were divided into three groups according to the initial intraocular pressure 41~50, 51~60, and over 60 ㎜Hg/AT, there was no significant difference of the laser iridotomy success rate between the groups.
Table 4. The success rates according to the period from the acute glaucoma attack to the treatment
Chi-square test
Days
L I success
L I failure
Total
P value
1-7 52 9 61
0.011*
>7 7 16
When the success rates of the laser iridotomies were compared in terms of the period from the acute glaucoma attack to the treatment, the laser iridotomy success rate was significantly decreased when the period exceeded 7 days.

8. Table 5. The success rates according to the response of maximum tolerable medical therapy
Chi-square test
Response
L I success
L I failure
Total
P value
Positive 40 2 42
<0.001*
Negative 21 14 35
Positive response was defined as over 30% decrease of the baseline IOP after treatment.
Table 6. The success rates according to the response of intravenous hyperosmotic agent (Mannitol®)
Fisher’s exact test
Response
L I success
L I failure
Total
P value
Positive 27
<0.001*
Negative 8 16
Positive response was defined as over 30% decrease of the baseline IOP after treatment.
95.24% (40/42 eyes) success was obtained in those showing over 30% IOP reduction after standard MTMT (p<0.001), especially 100% (27/27 eyes) when showing over 30% IOP reduction after intravenous hyperosmotic agent treatment, but only 50% (8/16 eyes) in those who did not (p<0.001)(Table 5,6).

9. Conclusions (I)
There were no significant differences of the success rate of the laser iridotomy between success and failure groups in terms of age, sex and the initial IOP.
The laser iridotomy would be easily successfully performed in the eyes with APAC presenting over 30% IOP reduction after standard MTMT within 7 days after the attack, especially showing IOP reduction to the intravenous hyperosmotic agent treatment.

10. Conclusions (II)
3. The longer duration from the glaucoma attack to the treatment lasts, the more damages to the aqueous outflow tract and peripheral anterior synechiae will occur. 4. Therefore further medical and surgical treatment for glaucoma may be necessary in these cases even if laser iridotomy has been performed successfully.