Implantation of cleral expanion band egment for the treatment of prebyopia

To ae the effect of cleral expanion band (EB) egment on accommodative amplitude (primary meaure), along with near and ditance viion, refraction, pupil ize and function, keratometry, axial length, intraocular preure, contrat enitivity, tereopi, and other parameter (econdary meaure) in a cohort of 29 emmetropic, prebyopic patient. Deign Multicenter, propective, nonrandomized, unmaked clinical trial in which the nonoperated eye erved a the control. Method Four polymethylmethacrylate egment were urgically implanted in quadrantic cleral pocket created in the dominant eye of 29 emmetropic patient who were between the age of 51 and 60 (mean age 54). Patient were examined preoperatively and up to 6 month potoperatively. The aforementioned tet were performed on the operated and control eye of each patient. Data were analyzed uing two-ided rank tet. Median, mean, and tandard deviation are provided for all meaurement. Reult Accommodative amplitude wa meaured monocularly uing a near-point “puh” technique from both a 70-cm and 30-cm tarting point. An increae in accommodative amplitude of urgical eye by +1.7 ± 1.5 diopter and +1.5 ± 1.2 diopter, at thee two teting ditance, repectively, wa noted at 6 month potoperatively (P < .0001). A maller increae wa alo een in control eye (+1.2 ± 1.1 diopter and +1.3 ± 1.2 diopter, repectively). There wa notable intercenter variation in gain in accommodation, with three of even center howing ignificant improvement in near-point accommodative amplitude relative to the other (P = .0003). There wa a median improvement of uncorrected near acuity in urgical eye by 0.3 logarithm of the minimal angle of reolution (logMAR) at 30 and 40 cm and by 4 line at 20 cm, with the difference in near acuity improvement at 6 month between EB eye and control eye tatitically ignificant at 20 cm (P < .030). Change in pherical equivalence, axial length, and central keratometry reading were not tatitically ignificant. There were no report of anterior egment ichemia or malignant glaucoma. Advere effect were limited to a tranient elevation of intraocular preure in one patient and mialignment of individual EB egment, due to inadequate cleral pocket formation, in three patient. Only one EB egment in one eye wa replaced. It appear that the thickne and uniformity of the cleral belt loop i critical to the proper poitioning and efficacy of the EB egment. Concluion While the afety profile of EB egment for the treatment of prebyopia wa high, a modet improvement in near viion wa noted in approximately half the patient uing ubjective method of teting. The mechanim that underlie improvement in near viion in the nonoperated eye await explanation. Thi may be due to a centrally controlled conenual repone, potentiated convergence generating increaed intravitreal preure and hydraulic lift of the vitreo-zonular-len diaphragm, or artifact from current teting technique. Future tudie of the EB procedure hould addre the iue of intercenter variation by further tandardizing and automating pecific apect of the urgical technique, a well a incorporating objective teting method into the tudy deign.