[Molteno implant and refractory glaucoma. Evaluation of postoperative IOP control and complications with a modified surgical procedure].
BACKGROUND
Management of refractory glaucoma is difficult because classic medical and surgical treatments are ineffective in controlling highly elevated intraocular pressure (IOP). Drainage implants are an alternative to cyclodestructive procedures in refractory glaucoma. The double-plate Molteno implant, a tube linked to two polypropylene plates, allows aqueous humor drainage from the anterior chamber towards the posterior subconjunctival spaces. The main postoperative complication is severe hypotony, potentially responsible for a decrease in visual acuity in cases of advanced glaucoma. Surgical modifications such as external tube occlusion can reduce postoperative hypotony. However, tube occlusion may lead to transient postoperative hypertony. Our retrospective study reports on double-plate Molteno implantation with intraoperative external tube occlusion associated with trabeculectomy in some cases.


METHODS
Thirteen eyes of 13 patients with refractory glaucoma were included in the study (5 cases of open angle glaucoma, 7 cases of secondary glaucoma, one case of primary congenital glaucoma). All had ocular hypertony despite maximal tolerable medical treatment; 84.5% had previously undergone trabeculectomy with mitomycin (1-5 procedures) and 61% had undergone cyclophotocoagulation (1-4 sessions). All underwent double-plate Molteno implantation with external tube occlusion between 1993 and 2001. In three cases, intraoperative trabeculectomy was also performed. Visual acuity, IOP, relevant medical treatment and potential complications were reported at each follow-up visit. Complete success was defined as IOP less than 21 mmHg without treatment, while IOP control with medical treatment was considered as relative success.


RESULTS
Mean (+/-SD) follow-up was 2.9+/-2.1 years (range, 9 months to 8 years). Mean (+/-SD) initial and final IOPs were 35.2+/-7 mmHg and 17.1+/-5 mmHg, respectively, i.e., a 50% IOP decrease. Mean (+/-SD) initial and final medical treatments were, respectively, 4.3+/-1.5 (61% with systemic acetazolamide) and 1.3+/-1.4 (without acetazolamide). The complete success rate was 38.5% and relative success 92.3%. Immediate postoperative hypertony occurred in 60% of the cases with external tube occlusion alone (10 cases). This hypertony was controlled with medical treatment in 2/3 of the cases but required surgical reintervention in 1/3 of the cases. For patients with intraoperative trabeculectomy (3 cases), postoperative immediate IOP without medical treatment was 2, 5 and 8 mmHg respectively. Complications reported were flat anterior chamber (1 case), visual acuity decrease (4 cases), lens opacification (1 case), macular edema (1 case), corneal edema (2 cases: 1 transient, 1 corneal decompensation) and long-term refractory hypertony (1 case).


CONCLUSIONS
The double-plate Molteno implant is effective in controlling IOP in refractory glaucoma. External tube occlusion prevents complications related to excessive filtration; however, it may lead to transient postoperative hypertony. This hypertony can be avoided when simultaneous trabeculectomy is performed. Corneal decompensation remains the major complication of this surgical procedure.
Hamard
P
P
Service d'Ophtalmologie, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, 28, rue de Charenton, 75012 Paris, France. pascale-hamard@quinze-vingts.fr
Loison-Dayma
K
K
Kopel
J
J
Hamard
H
H
Baudouin
C
C
D000086:Acetazolamide / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D002257:Carbonic Anhydrase Inhibitors / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000601:surgery*; D005902:Glaucoma, Open-Angle / Q000601:surgery; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D018465:Molteno Implants; D012189:Retrospective Studies; D013997:Time Factors; D014130:Trabeculectomy
D002257:Carbonic Anhydrase Inhibitors; D000086:Acetazolamide