POSTERIOR CAPSULAR OPACIFICATION Incidence and Factors Influencing the Rate of Nd:YAG Capsulotomy in Diabetic and Uveitic Patients and after Multifocal Intraocular Lens Implantation

This thesis examined the incidence and factors affecting the rate o f posterior capsular opacification (PCO), the most com mon complication o f cataract surgery, in diabetic and uveitic patients and in patients with multifocal intraocular lenses (IO L s). These patients are particularly sensitive to PCO developm ent because o f the risks associated with Nd:Y AG capsulotom y in the former two groups and the potential effect on visual function in the latter group. PCO rate was estimated both retrospectively, using N d:Y A G capsulotomy as a surrogate m easure o f clinically significant PCO, as well as prospeetively using clinical and im aging methods. Diabetic patients were found to have a lower incidence and risk o f Nd:YAG capsulotomy than non-diabetic patients within 4 years after surgery. Y oung age, postoperative inflammation, pars plana vitrectomy and, in comparison to 3-piece silicone lOL, polym ethylmethacrylate (PM M A ) and plate-haptic silicone IOLs were associated with increased risk o f N d.Y A G capsulotomy. In subgroup analysis, male gender was found to be a risk factor in the non-diabetic group and the duration and type o f diabetes and diabetic retinopathy grade were not risk factors. In a prospective randomised trial, hydrophobic acrylic IOLs, while associated with a higher flare value within the early postoperative period, had a significantly lower rate o f PCX) development than plate-haptic silicone IOLs after 6 months and 1 year in diabetic patients. Optical coherence tom ography revealed the development o f a characteristic mid-peripheral apposition between the optic and the posterior capsule with hydrophobic acrylic IOLs both early and late after surgery, and the lack thereof with plate-haptic silicone IOLs, which is consistent with and explains the difference in PCO rate between the two IOLs. In uveitic patients, the incidence o f Nd:Y AG capsulotomy was higher within the first two years after surgery than in non-uveitic patients, although the presence o f uveitis was not an independent risk factor for an increased rate o f N d:Y AG capsulotomy. The use o f preoperative systemic steroids reduced the risk o f N d .Y A G capsulotom y and, in comparison to PM M A IOLs, silicone IOLs reduced the risk o f Nd:YAG capsulotomy while hydrophilic acrylic IOLs and young age increased it. In patients with multifocal IOLs, within 4 years o f follow-up the incidence o f PC'O and Nd:YAG capsulotomy were similar to those reported with monofocal implants