Top-Ten of the Fourth Angle-Closure Glaucoma Club Meeting
October 29-30, 2005, Taipei, Taiwan
| Por-tying Hung
- Since PACG is in large part due to the anatomic make-up of
the eye, it is possible that genes that control ocular growth, as
well as genes coding for collagen and extracellular matrix tissue,
may be associated with the development of PACG.
Professor Wang identified variations in genes coding for MMP9 using
SNP-based genotyping in a case-control study of acute primary
angle-closure patients. MMP9 may play a role controlling the
development of anterior segment structures.
- Anterior segment optical coherence tomography (AS-OCT) can
obtain high-resolution images of the angle and allows qualitative
and quantitative angle analysis. The technique produces high-quality
images permitting a dynamic, cross-sectional view of the irido-trabecular
angle. Superior performance in detection of angle-closure when
compared with gonioscope was reported.
- Investigators from the Tajimi Eye Study (a population-based
study of eye disease among 3,021 Japanese subjects of the age of 40
years and older) reported that the prevalence of PAC (including PACG
and suspected PACG) was 1.3% and that of PAC excluding PACG
suspected PACG was 0.5%. PACG was defined using standard definitions
and required both optic nerve and visual field abnormalities in most
cases. As in previous research, the prevalence of PAC significantly
increased with age.
- Glaucoma is the leading cause of irreversible blindness.
Angle-closure accounts for about half of all glaucoma cases, and a
higher proportion of glaucoma blindness than POAG. Most cases of
angle-closure are asymptomatic. The traditional (symptomatic)
classification does not promote a clear understanding of mechanisms
responsible for closure, nor the physical characteristics that
indicate prognosis. An ideal classification system should identify
both stage of disease and mechanism of closure. Further refinement
of definitions of narrow angles and associated glaucoma was urged.
- In study of visual outcomes of the contralateral eyes, 76
persons presenting with a unilateral attack of acute primary angle
closure (APAC) in Singapore, three eyes (3.8%) had glaucoma at the
time of diagnosis of APAC, and an additional four (5.1%) developed
PACG during a mean follow-up of six years. Cataract was common in
fellow eyes. All fellow eyes had laser iridotomy at the time of the
attack, and most did well with low eye pressure and no glaucoma in
long-term follow-up.
- Nd:YAG laser iridotomy is effective in increasing angle width
and controlling intraocular pressure in the early stage of primary
angle-closure in Mongols. However, once extensive synechiae or
glaucomatous optic neuropathy associated with angle closure have
occurred, iridotomy also is less effective in achieving IOP control.
(By D. Uranchimeg, Mongolia.)
- The biometric evaluation of 77 subjects with convex iris
configuration (CIC) and 38 plateau iris configuration showed
significant thicker lens and smaller vitreous length in CIC.
- Incidence of zonular weakness was significantly higher in cases
of primary angle-closure glaucoma.
- Although PACG is a big health problem in China, community-based
screening does not appear cost-effective at this time. Screening
should be combined with efforts to detect other preventable blinding
eye diseases (such as cataract and refractive error). Reasonable
screening intervals need to be determined.
- Complex biochemical changes which compromise the function of the
extracellular matrix can occur in the inflamed eye. Following
angle-closure, the trabecular meshwork function may remain impaired
as a consequence of inflammatory processes, regardless of whether
peripheral anterior synechiae develop or not.
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