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Top 10 - Canadian Glaucoma Society Annual Meeting
June 16-19, Vancouver, Canada
Gordon Douglas
- The effects of glaucoma in the human brain were further characterized by Yucel and his group at our annual meeting in Vancouver this June. The brains of 5 glaucoma patients (visual field / optic nerve head changes) were examined histopathologically, and compared with those of 5 age-matched controls. As well as samples from the optic nerve, sections were taken from the right hemispheres every 150 microns from the LGN posteriorly and stained for glia, axons, and neurofilaments. Axon loss and atrophy was marked in the optic nerve and LGN and, as well; the volume of the LGN decreased significantly when compared with the normals. In addition, there was a disruption of the cytoarchitecture of the primary visual cortex with loss of the laminar organization and a reduction of cortical thickness. It is now clear that data gathered in the past on subhuman primates with glaucoma is reflected in the human model as well.
- Carrillo investigated the effect of IOP change on results from the HRT IIR when medical therapy was stopped in one eye and not the other. A significant difference ( 5.2 mmHg) was found in the eye which had been withdrawn as compared to the eye in which no change in therapy had taken place. Three examinations were done on each occasion before, 1, 2, 4, and 8 weeks after therapy withdrawal on 17 POAGs. Therapy was restarted after the 4 week visit. No change was found in rim area and cup depth over the course of the study.
- A novel application of the RetcamR(ADIS-9000R)was described by Ahmed who used it as a goniocamera. Impressive pictures of the angle were shown for both normals and pathological patients.
- Anterior chamber(A/C) depth in plateau iris syndrome was analyzed by Mandell who gathered 137 pupil block and 181 plateau iris syndrome eyes (the latter diagnosed by ultrasound). The A/C depth was measured with ultrasound, post-iridotomy. The results showed a significant decrease in depth in plateau iris syndrome relative to pupil block eyes which were, in turn, less than normals. Both eyes of some patients were used in this analysis.
- Using TonopenR and GoldmannR tonometry (the gold standard) values from 290 eyes, Rodriguez reported that the central corneal thickness (CCT), using ultrasonic pachymetry, was not totally related to a linear model but rather was more non-linear. The error between the 2 tonometers, and correlated to CCT, was best described by a linear model above 555 microns (1.01-1.13 mmHg / 20 micra). Those below this value were closer to the IOP as determined by Goldmann tonometry (0.41 mmHg / 20 micra).
- Ahmed reported a series of ultrasonic CCT measurements done on a consecutive population from a mixed race neighbourhood in Toronto. It was found that females had thinner corneas (males- 552, females- 545; p=.005) and East Indians also had thinner corneas (535 vs. 558 for Caucasians; p<.001). The expected thin corneas from African-Canadians was confirmed and the difference between they and the East Indian population was marginally significant (p=.05).
- An ongoing study by Pan and Damji to compare SLT with ALT was analyzed for any predictive elements which might help in determining future success. Eighty-nine patients in the SLT arm were analyzed and it was found that the only significant factors were pre-laser IOP and IOP 1 hour after laser.
- A multicentre study comparing IOP response to phacoemulsification surgery in pseudoexfoliators (PEX) and in non-PEX patients was reported by Damji. The 2 groups (PEX=71; non-PEX=112) each had 29 glaucoma patients. An average IOP change of -2.64 mmHg was found in the PEX group @ 1 year and 2.71 @ 2 years. This was significantly lower than the non-PEX group at both times - p=.007 @ 1 year and p= .012 @ 2 years. The only correlation for the IOP decrease was a significant increase in irrigation volume in the PEX population (p= .005 @ 1 year and p= .023 @ 2 years) as opposed to the non-PEX group in which there was no correlation.
- Harasymowyzc reported a series of acute and subacute angle closure patients who had failed primary iridotomy and whose IOPs were unacceptable (45 mmHg). Surgical management included argon peripheral iridoplasty in 12 cases and phaco surgery combined with synechiolysis in 22 cases. Argon iridoplasty was successful in 58% whereas the subsequent combined procedure was successful in all but a single remaining eye. In that case trabeculectomy was successful. A longer time between recognized onset and intervention was predictive of a need to proceed to more aggressive surgery. It was concluded that these 2 procedures are often advantageous given certain diagnoses and circumstances.
