Optical coherence tomography for an in-vivo study of posterior-capsule-opacification types and their influence on the total-pulse energy required for Nd:YAG capsulotomy: a case series.

BACKGROUND: Posterior capsule opacification (PCO) is the most common post-operative complication associated with cataract surgery and is mostly treated with Nd:YAG laser capsulotomy. Here, we demonstrate the use of high-resolution spectral-domain optical coherence tomography (OCT) as a technique for PCO analysis. Additionally, we evaluate the influence of PCO types and the distance between the intraocular lens (IOL) and the posterior capsule (PC), i.e., the IOL/PC distance, on the total-pulse energy required for the Nd:YAG laser posterior capsulotomy. METHODS: 47 eyes with PCO scheduled for the Nd:YAG procedure were examined and divided into four categories: fibrosis, pearl, mixed type and late-postoperative capsular bag distension syndrome. Using custom-made computer software for OCT image analysis, the IOL/PC distances in two dimensions were measured. The IOL/PC distances were compared with those of a control group of 15 eyes without PCO. The influence of the different PCO types and the IOL/PC distance on the total-pulse energy required for the Nd:YAG procedure was analyzed. RESULTS: The total-pulse energy required for a laser capsulotomy differs significantly between PCO types (p = 0.005, Kruskal-Wallis test). The highest energy was required for the fibrosis PCO type, followed by mixed, pearl and late-postoperative capsular bag distension syndrome. The IOL/PC distance also significantly influenced the total-pulse energy required for laser capsulotomy (p = 0.028, linear regression). Lower total-pulse energy was expected for a larger IOL/PC distance. CONCLUSIONS: Our study indicates that the PCO types and the IOL/PC distance influence the total-pulse energy required for Nd:YAG capsulotomy. The presented OCT method has the potential to become an additional tool for PCO characterization. Our results are important for a better understanding of the photodisruptive mechanisms in Nd:YAG capsulotomy.

Multiscale roughness approach for assessing posterior capsule opacification.

Posterior capsule opacification (PCO) is a common complication in patients who have undergone cataract surgery, occurring in up to 50% of patients by two to three years after the operation. Assessment of PCO has been mainly subjective, making it difficult to understand its progression over time or assess the effectiveness of strategies used for the prevention of PCO. Fully automated PCO assessment systems developed so far offer objective grades. However, they do not provide morphological PCO data useful for an effective analysis of scores. This paper proposes a novel method based on multiscale roughness estimation to detect and quantify the PCO areas. This method is also characterized by its robustness against monotonic illumination variations. Extensive experimentation showcases a distinctive analysis and assessment power of our method compared to other competitive methods. The results show a high correlation of 84.6% with respect to clinical scores.

Intracameral mydriatics in phacoemulsification cataract surgery -- a 6-year follow-up.

PURPOSE: To evaluate the long-term safety of intracameral mydriatics (ICM) in phacoemulsification cataract surgery compared with conventional topical mydriatics (TM). METHODS: A total of 45 patients were examined 6 years after phacoemulsification cataract surgery. The patients had previously participated in a prospective randomized double-blind study including 60 patients, operated with either ICM or TM. The follow-up included best-corrected visual acuity (BCVA), intraocular pressure (IOP), grade of posterior capsule opacification (PCO), YAG laser capsulotomy rate, pupil size, corneal thickness and endothelial morphology. RESULTS: No differences in postoperative BCVA, IOP, pupil size, PCO or YAG rate were observed between the groups. Endothelial cell loss, endothelial morphology and corneal thickness were also equivalent. CONCLUSIONS: Intracameral mydriatics is a safe alternative to topical mydriatics in phacoemulsification cataract surgery with no long-term disadvantages at 6-year follow-up.