Pseudoexfoliation syndrome (PXFS) is a disease characterized by the accumulation of abnormal fibrillar extracellular material
in ocular structures. When, however, this syndrome is associated with increased intraocular pressure (IOP) and optic nerve
damage it is known as pseudoexfoliative glaucoma (PXFG).
Reports on the rate of glaucoma development amongst PXFS sufferers vary in the literature. In 2002, a report by Puska and
co-workers reported a conversion rate of 3.2% PXFS cases per year to PXFG.1 Elsewhere, a team led by Jeng found that, in patients with PXFS, the probability of developing glaucoma was 44% after 15
years2 whilst a study by Grodum, et al., found 55.1% of PXFS patients went on to develop glaucoma after a mean of 8.7 years.3 In the Early Manifest Glaucoma Trial, the risk of glaucomatous progression over a six-year period was found to be 2.2 times
higher in PXFG patients, compared with non PXFG sufferers.4
The labile nature of IOP, and the high diurnal IOP fluctuations experienced by sufferers, makes exfoliative glaucoma one of
the most difficult forms of open-angle glaucoma to manage.
Current management techniques include:
- Regular follow-up of patients (including those with normal IOPs and optic discs).
- Early use of topical anti-glaucoma medications.
- Surgical treatment (including laser trabeculoplasty and filtration surgery) in patients resistant to medical therapy.
Argon laser trabeculoplasty (ALT) has been used to treat PXFG patients with excellent initial success, however, many studies
have shown that there are risks involved with this procedure: post-treatment increase in IOP, coagulative damage and scarring
to the trabecular meshwork, and it may also limit the efficacy of further non-surgical therapy. Thus, the number of users
of ALT has been dwindling in recent years. Selective laser trabeculoplasty (SLT), on the other hand, has been shown in studies
to be equally efficacious to ALT in reducing IOP, but this procedure is without the side effects that are more commonly seen
with ALT, such as thermal damage to the trabecular meshwork.
Proving the point
To better evaluate the response to SLT in eyes with PXFG, a retrospective chart review of patients who underwent SLT from
January 2000 to December 2005 was performed (571 eyes in total). Of those, 24 eyes of 21 patients (11 male, 10 female; mean
age 72 years) had either PXFS or PXFG and were available for analysis.
Of the 21 patients treated, three received SLT treatment in both eyes, whilst the remaining 18 patients were treated in one
eye. 17 eyes in total underwent 180° SLT treatment and seven underwent 360° SLT treatment (average laser power used was 0.7
mJs). Mean follow-up was 36 months.
Over the follow-up period, IOP decreased by 43% from a mean preoperative level of 28.3 mmHg to a mean postoperative level
of 16.1 mmHg (Figure 1). Of the patients included in this review, 67% responded well to SLT treatment and achieved the targeted IOP, 11% were non-responders
i.e. no noticeable reduction in IOP, and 22% responded to SLT but the effect diminished over time, thus these patients were
labelled failures (Figure 2).