1. Tulsi Changulani 1,*, Jenny Bo 2, Mei-Ling Cheng 1, Andrew Tatham 1
WGCSUB A Study Of Factors Predicting Future Lens Extraction Following Laser Peripheral Iridotomy
Tulsi Changulani 1,*, Jenny Bo 2, Mei-Ling Cheng 1, Andrew Tatham 1
1Ophthalmology, 2Princess Alexandra Eye Pavillion, Edinburgh, United Kingdom
Primary angle closure glaucoma (PACG) is a common cause of blindness (1).
The current first line treatment is laser peripheral iridotomy (LPI), however a significant proportion of eyes need further treatment, especially lens extraction.
A recent randomised control study has shown primary lens extraction to be effective and cost effective for eyes with PACG and primary angle closure (PAC) with raised intraocular pressure (IOP) (2).
AIM - To evaluate the outcome of LPI for the initial management of angle closure and determine predictors of future lens extraction.
INTRODUCTION
RESULTS (cont.)
Overall, at one year following LPI there was a 20% chance of having had lens extraction, increasing to a 50% chance at 4 years (Figure 1).
Each year of increasing age was associated with a 1.06-fold increase in chance of needing lens extraction (95% CI 1.04 to 1.08, P<0.001).
Univariate Cox proportional hazard regression analyses showed older age, higher IOP prior to laser, PACG diagnosis, shorter axial length, and worse SAP MD at baseline were significantly associated with lens extraction (P <0.05).
A retrospective chart review including 218 consecutive eyes of 118 subjects treated with LPI between 23rd November 2010 and 23rd May 2012 at Princess Alexandra Eye Pavilion.
Baseline information collected included age at LPI, gender, diagnosis (primary angle closure suspect (PACS), PAC or PACG), gonioscopy, central corneal thickness, peak IOP prior to LPI, visual field mean deviation (MD), axial length, number of anti-glaucoma medications prior to LPI and number at most recent follow up.
The study endpoint was defined as date of lens extraction or date of most recent follow up.
Survival analysis was performed using Kaplan-Meier curves. Univariate and multivariate analysis were performed to determine factors associated with increased likelihood of lens extraction.
METHODS
Table 1. Additional treatment following LPI for control of IOP.
Figure 1. Kaplan-Meier survival probability for phacoemulsification
54.1% of all eyes required additional surgical treatment following LPI, the most common of which was lens extraction.
The multivariate model was used to predict survival probabilities (Figure 2) for lens extraction based on age and peak IOP before laser.
Patients who were older, had higher peak IOP prior to laser, PACG diagnosis, shorter axial length, and worse SAP MD at baseline were significantly more likely to need lens extraction during follow up.
Patients at high risk of needing lens extraction following LPI may be better having lens extraction as the primary procedure.
DISCUSSION HR
95% CI
P-value
Age (per year older)
1.03
1.00 to 1.05
0.027
Peak IOP before laser (per 1 mmHg higher)
1.01 to 1.05
0.004
Axial length (per mm longer)
0.68
0.52 to 0.90
0.007
Average age at time of LPI was 68 ± 11 years and patients were followed for an average of 3.7 ± 1.6 years after LPI.
111 of 218 eyes (50.9%) had PACS, 42 (19.3%) PAC and 65 (29.8%) PACG.
91 of 218 eyes (41.7%) underwent lens extraction following LPI, including 31.5% of eyes with PACS, 35.7% with PAC, and 63.1% with PACG (Table 1).
RESULTS
Table 2. Multivariate Cox proportional hazard regression analysis.
Predicted survival probabilities for phacoemulsification
Additional Treatment
PACS (n=111)
PAC (n=42)
PACG (n=65)
No.
Percentage
Phacoemulsification 35
31.5% 15
35.7% 41
63.1%
Repeat/enlargement of PI 18
16.2% 6
14.3% 24
36.9%
Cyclodiode Laser 1
0.9% 2
4.8% -
Trabeculectomy
1.5%
Selective Laser Trabeculoplasty
2.4%
Figure 2. Multivariate predicted survival probabilities for phacoemulsification.
Increased age, peak IOP prior to laser, severity of glaucomatous changes and shorter axial length at baseline predicted earlier intervention with lens extraction.
CONCLUSION
Table 1. Additional treatment following LPI for control of IOP.
European Glaucoma Society. Terminology and Guidelines for Glaucoma. 4th ed. Savona, Italy: PubliComm; 2014.
Azuara-Blanco A, Burr J, Ramsay C, Cooper D, Foster PJ, Friedman DS, et al. Effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE): a randomised controlled trial. Lancet. 2016;388(10052):