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Assessment of Anterior Chamber Angles – Scanning Peripheral Anterior Chamber Depth Analyser (SPAC) compared to Gonioscopy . Johnson CH TAN , MBBS, MRCSEd(Ophthalmology) Colin SH TAN , MBBS, M Med (Ophthalmology), MRCSEd (Ophthalmology), FAMS
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Assessment of Anterior Chamber Angles – Scanning Peripheral Anterior Chamber Depth Analyser (SPAC) compared to Gonioscopy Johnson CH TAN, MBBS, MRCSEd(Ophthalmology) Colin SH TAN, MBBS, M Med (Ophthalmology), MRCSEd (Ophthalmology), FAMS The authors have no financial interest in any of the products mentioned
Literature Review • A newly developed peripheral anterior chamber depth analysis system: principle, accuracy, and reproducibility. • K Kashiwagi et al. Br. J. Ophthalmol. 2004;88;1030-1035 • Computer installed program automatically evaluate the ACD, CT and CRC. • Dummy eye was used for investigation. • 3 examiners measured ACD in 10 normal eyes (shaffers’ grade 3 or 4) and inter-observer and intra-obserever reproducibility analysed.
Literature Review • Quantitative evaluation of changes in anterior segment biometry by peripheral laser iridotomy using newly developed scanning peripheral anterior chamber depth analyser. • K Kashiwagi et al. Br. J. Ophthalmol. 2004;88;1036-1041 • Finding cases of angle closure glaucoma in clinic setting using a newly developed instrument. • Kashiwagi K et al. Eye. 2006 Mar;20(3);319-24 • No studies so far to compare the gradings of SPAC versus that of gonioscopic findings with shaffer’s grading.
Objective • To assess the correlation between the scanning peripheral anterior chamber depth analyser (SPAC) and gonioscopy in the assessment of the anterior chamber angles.
Method • Prospective analytical study performed at Tan Tock Seng Hospital, Singapore. • The temporal anterior chamber angles of patients seen at the ophthalmology outpatient clinic were assessed by SPAC (graded from 1 to 12) and gonioscopy performed by a single masked investigator using the Shaffer’s grading (grades 1 to 4).
Method • Exclusion criteria : • Patients with peripheral corneal disease. obstructing the view of the angles • peripheral anterior synechiae. • patients whose pupils were pharmacologically dilated.
Demographics • Age distribution • Mean 60.6 (SD ±12.6), range 38-83 N = 37
Comparison of SPAC vs Sex P=0.100
Comparison of SPAC vs Race P=0.101
Comparison of SPAC vs Gonioscopy P<0.001
Correlation of SPAC and Gonioscopy • Spearman’s correlation coefficient • (r) = 0.699 • (p<0.001)
Discussions • Gonioscopy remains the gold standard in evaluating the angles. • However, subjected to inter-observer and intra-observer variability. • Limitations of SPAC : unable to pick up peripheral anterior synechiae.
Conclusion • SPAC correlates well with the gradings of gonioscopy. • All gonioscopy gradings of 2 or less have SPAC grades of 6 or less. • But some with gonioscopy gradings of 3 or more have SPAC grades of 6 or less. • Performing gonioscopy on SPAC grades of 6 or less appears to pick up the narrow angles.