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Report of the 2nd Latin American Glaucoma Society Meeting
Cancun, Mexico, April 20-21, 2000
Remo Susanna
The Latin America Glaucoma Society (LAGS) is made up of 32 members whose purpose is research and collaborative studies in glaucoma.During the expert meeting, the early diagnosis and progression of glaucoma were discussed at the first session. W. Sponsel showed that SWAP and FDP could be incorporated into clinical practice in order to detect early functional losses in glaucoma. He stressed that FDP is efficient enough for routine glaucoma screening. During his second lecture: Neuroprotection and optic nerve blood flow: what is the role in the treatment of glaucoma?, after a lively discussion, he pointed out that, although there are many studies going on, there is no definitive proof that these eyedrops have any effect on human glaucomatous eyes.
GDx
Should GDx be incorporated into clinical practice? P. Mello presented a study which demonstrated that GDx results are not correlated with conventional perimetry in 48.7% of early glaucoma cases. He believes that this new technique will be helpful in a few situations in ophthalmological practice.
Perimetry
R. Susanna presented a study showing that, in 18 normal contralateral eyes, on conventional perimetry, seven (38.8%) presented with a visual field defect on blue-yellow perimetry and ten (55.5%) with a defect of the nerve fiber layer on GDx. With regard to the ten eyes that presented with a defect on blue-yellow perimetry, he showed some clinical cases that demonstrated a good correlation with the clinical picture, GDx results and FDP, but not with conventional perimetry. Pitfalls in the evaluation of GDx were also discussed, such as peripapillary atrophy and uncorrected corneal polarization.
Medical Treatment
T. Zimmerman explained the action of prostaglandins, their ocular distribution, efficacy and side-effects, such as uveitis, herpes, keratopathy and CME. He pointed out that prostaglandins are not the cause of the CME, but that aphakic patients or those who have previously had CME are more prone to develop such complications.
In his study, J. Quesada from San Salvador showed that latanoprost alone was able to control intraocular pressure (IOP) in
76% of primary open-angle glaucoma patients. R. Susanna presented an eight-week randomized, double-masked study comparing latanoprost with unoprostone in open-angle glaucoma and ocular hypertension, concluding that latanoprost used once daily was significantly more effective in reducing IOP (-6.7 mmHg mean baseline IOP) than unoprostone administered twice daily (-3.3 mmHg mean baseline IOP).
R. Yamane showed that latanoprost reduced the mean IOP from 18.7 to 15 mmHg in patients receiving timolol treatment. R. Susanna showed that latanoprost added to timolol and dorzolamide therapy in 47 patients showed a significant reduction in IOP of 3.1mmHg (16%) from a baseline of 19.3 mmHg mean IOP (p<0.0001). Seventeen patients (36.3%) showed a mean IOP reduction of over 20%.
D. Grigera discussed the efficacy and side-effects of glaucoma drugs. Latanoprost is the most efficiency in reducing IOP. Should it be stated that if its side-effects do not impair ocular safety, it could become a first line therapy in primary open-angle glaucoma and normal tension glaucoma.
Paul Palmberg in his lecture, What damages optic nerve in glaucoma?, stressed the importance of IOP and the need to chose a target IOP for each patient. He also gave the SLAG lecture, Glaucoma tube implants versus MMC. He pointed out the need for studies comparing these two techniques.
Surgery
On the second day, several studies were discussed. R. Susanna showed four months of follow-up in two cases (from the multicenter study conducted by SLAG), in which a special Ahmed valve was implanted in tenonectomized eyes with adjunctive use of MMC. No capsule formation or hypertensive phase was seen during this period. Neither did any complications occur.
M. Araújo from Cali, Colombia, presented her results with an Ahmed valve implant in glaucomas related to vitreous and/or retinal problems. Overall success was achieved at the last postoperative visit in 22/29 patients (75.8%; complete, 14%; qualified, 62%). There were seven (24%) failures. The probability of success was 75.9% at three months and 65.5% at one year.
UBM
D. Grigera conducted a study to examine cases of postsurgical anterior chamber (AC) flattening with UBM. Deformation of the trabeculectomy internal ostium was described. All cases had a ring-shaped ciliochoroidal effusion which showed no positive results on conventional ultrasonography.
S. Cronemberg reported the UBM findings of 31 patients with angle closure glaucoma related to the pupillary block. He showed that iris-lens contact increases after the iridotomy.
Image Analysis
W. Barboza showed that the ability of the HRT to diagnosis glaucoma is poor, due to the wide variability of optic nerve head topography in normal eyes. Discriminating analysis gave a sensitivity of 66% and a specificity of 85.9% in glaucoma patients with early functional loss (MD <10 dB).
J. Prata noted that there are differences in drop size between Brazilian and similar North American antiglaucomatous eyedrops. The mean drop volume of Timoptol® in Brazil was 14.7% (9.8-19.0%) larger than the imported one. Mean Brazilian eyedrop volume was statistically larger in bottles of Alphagan,®, Betoptic-S®, and Iopidine 0.5. Significant differences were noted in treatment duration and annual costs.
P. Guelman and R. Susanna observed that bottles of Trusopt®, Timoptol 0.5%® and Alphagan®, the contents of which were all 5 ml, had a different number of drops (156, 143 and 112 drops, respectively). Due to the rigidity of the bottles and the size of the tips, there is wastage when patients use these drugs. A bottle of Trusopt® contained enough for 63 instillations (wastage of 60%), Timoptol 0,5%® for 94 (wastage of 35%) and Alphagan® for 89 (wastage of 21%).
Climax
The climax of the meeting was the presentation and discussion of protocols for collaborative studies in Latin America. Studies regarding valve implants, genetics, new perimetric techniques, and ocular blood flow evaluation, will be carried out.