Abstract
Abstract: :
Purpose: To study anatomical relationship and position in relation to endothelium of three models of anterior segment angle supported phakic intraocular lenses (IOLs) used for high myopia correction. Methods: Seventy five high myopic eyes corrected with phakic angle supported IOLs were divided in three groups according to the IOL model: rigid optic and Z–shaped haptics in groups A and B: Group A: 20 eyes (5.0mm–optic, 4.0mm–optical zone, model ZB5M, Chiron®); Group B: 44 eyes (5.0mm–optic, 4.5mm–optical zone, model Nuvita®, Bausch&Lomb Surgical); and foldable optic with tripoidal haptics in Group C: 11 eyes (5.5mm–optic, 5.5mm–optical zone, model VivarteTM, Cibavision Surgical). Preoperative spherical equivalent (SE): Group A (SE range –10.62 Sph to –18.75Sph); Group B (SE range –11.12Sph to –27.12Sph); Group C (SE range –12.50Sph to –19.75Sph). Postoperative ultrasound biomicroscopy (UBM, 50MHz) was performed evaluating IOL anatomical relations, and determining central and peripheral distances (IOL periphery) from endothelium to IOL. Results: Mean IOL dioptric power was: Group A: –14.60D (SD=2.04D); Group B: –16.36D (SD=2.21D); Group C: –15.32D (SD=1.90D). Considering the anterior segment anatomy, in Group A iris retraction was detected at the distal part of the haptics; in Groups B and C, no iris retraction. Respectively the average central and peripheral distances from endothelium to IOL were measured in each group: Group A: 2.17mm (SD=0.17mm) and 1.65mm (SD=0.21mm); Group B: 2.10mm (SD=0.19mm) and 1.65mm (SD=0.18mm); Group C: 2.26mm (SD=0.14mm) and 1.31mm (SD=0.12mm). In NuVita® model there was estimated a 2.6mm distance from endothelium to IOL. Using UBM, this was demonstrated 0.5mm smaller centrally and 1.0mm smaller in periphery. Model Vivarte presents an even smaller distance to endothelium than the rigid models, explained by the increased optical part diameter in this model. Conclusions: UBM measurements indicate IOL periphery as the most probable area of endothelial touch. Measurement comparison in angle supported phakic IOLs demonstrate that the increase in optic size causes an increase of endothelium damage risk. UBM proved to be an efficient method in the postoperative evaluation of phakic IOLs and possible complications, such as under and oversizing.
Keywords: myopia • refractive surgery: phakic IOL • clinical (human) or epidemiologic studies: systems/equipment/techniques