ABSTRACT
Trauma is the main cause of subluxation or dislocation of the lens followed by ocular surgery and spontaneous dislocation due to hypermature cataract. Other causes are Marfan’s, Homocystinuria, Ehler Danlos syndrome and pseudoexfoliation. We report a case of dislocated lens by a trivial trauma with a wooden stick which was left unattended unless patient noticed decreased vision in that eye.
ABSTRACT
To update the accommodation mechanisms and propose a dual-wavelength, dual-function laser system for presbyopia and glaucoma treatments.Study Design: Laser sclera softening (LSS) for increased accommodation of presbyopic eyes.Place and Duration of Study: New Taipei City, Taiwan, between Jan., 2023 and Feb., 2023.Methodology: Accommodation gain (AG) can be improved by: (i) thermal shrinkage of the scleral stroma and ciliary body, or (ii) softening of the scleral stroma (with temperature range of 700C to 900C), such that the the lens front and back curvature change (or lens thickening), leading to the thickening of ciliary body and its apex, and the increase of the space of ciliary body and lens equation (SCL), and the length of the posterior vitreal zonules (PVZ) increases.Results: A novel dual-color laser system having wavelength A and B, acting on the front-zone and back-zone of the sclera, respectively, where laser-A has a deep thermal penetration the sclera and ciliary body (CB) (0.5 to 1.0 mm); and laser-B has a shallow penetration depth in the sclera (0.3 to 0.5 mm), based on the optical property of the sclera. Laser-A (having a wavelength about0.8 to 0.98 um) leads to thermal shrinkage of the ciliary body such that the CLS is increased for accommodation gain which is much more effective than the prior art.Conclusion: The increase of AG can be achieved by scleral softening and ciliary body shrinkage which increase the SCL. A proposed novel dual-color laser system acting on the front-zone and back-zone of the sclera, respectively, could provide higher AG than that of single wavelength, or prior arts using scleral ablation. However, further clinical studies are required to justified the proposed novel system with predicted advantages and efficacy based on the optical properties of sclera.
ABSTRACT
·AIM: To quantitatively assess the influence of pars plana vitrectomy (PPV) on the length of lens zonules and anterior chamber depth (ACD). ·METHODS: The medical records of 87 cataract patients (88 eyes ) were retrospectively reviewed. Forty- three patients (44 eyes) with previous PPV were included in the study group, and 44 patients (44 eyes) without a history of PPV were served as control group. Length of zonules and anterior chamber depth ( ACD ) were quantitative analyzed based on the data from ultrasonic biomicroscopy (UBM) and IOL Master examinations respectively. ·RESULTS: The average length of zonules in study and control group were 1. 09 ± 0. 24mm and 0. 78 ± 0. 22mm, respectively, and the difference was statistically significant (P<0. 05). The ACD of the two groups were 3. 25 ± 0. 39mm and 3. 44 ± 0. 48mm, respectively, and a statistical difference was observed (P<0. 05). The length of zonules in the control group was positively correlated with the ACD (r=0. 468, P=0. 001), however, this was not the case in the study group (r=0. 173, P=0. 263). ·CONCLUSION: Previous vitrectomy may cause changes in zonular length, which may imply a possibly weakened zonules, especially for patients with the axial length less than 29mm. The change in anterior chamber depth in patients with previous PPV may not be correspondent to that in the length of zonules. The findings of our study suggest that preoperative conditions of zonules and anterior chamber should be fully understood to reduce the related complications and to improve the safety and efficiency of cataract surgery after pars plana vitrectomy.
ABSTRACT
We examined the anatomical barrier for both anterior capsular tear extension and posterior capsular rupture extension which are the most serious intraoperative complications during cataract surgery, using 28 human eyes obtained postmortem. An experimental radial tear, about 1.0 mm in size, was created on the 5.0 mm capsulorhexis margin in the 1st group(7 eyes). Lens nucleus was removed mechanically with hydrodissection and viscoexpression technique. Radial tear extension did not extend over the lens equator in six eyes, and in one eye stopped in front of Wieger's ligament. In the 2nd group(7 eyes), after making zonular rupture around 90 degrees, same procedures were performed. Radial tear extension stopped at the equator in four eyes, and in three eyes stopped in front of Wiegel's ligament. In the 3rd group(7 eyes), we performed capsulorhexis and routine phacoemulsification for lens nucleus and cortex removal. Then we created only a posterior capsule rupture with intact anterior hyaloid membrane and vitreous pressure was increased. Posterior capsular rupture extension stopped in front of Wieger's ligament in all seven eyes. In the 4th group(7 eyes), after creating the rupture of the posterior capsule including anterior hyaloid membrane, intraocular lens was inserted into the empty capsular bag as a perpendicular direction to the axis of the tear. Posterior capsular rupture extension passed Wieger's ligament in only one eye, but did not reach equator or anterior capsule. In this study, we found that zonules, equator portion of the capsular bag and Wieger's ligament act as anatomical barriers for anterior capsular teal extension as well as for posterior capsular rupture extension.