Posterior Corneal Surface Stability after Femtosecond Laser-Assisted Keratomileusis.

The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored correlation between corneal ablation depth, residual corneal thickness, percentage of ablated corneal tissue, and preoperative corneal thickness. During follow-up, the posterior corneal surface did not have a significant forward corneal shift: no significant linear relationships emerged between the anterior displacement of the posterior corneal surface and corneal ablation depth, residual corneal thickness, or percentage of ablated corneal tissue.

Influence of pseudophakic lens capsule opacification on spectral domain and time domain optical coherence tomography image quality.

PURPOSE: To evaluate the influence of posterior capsule opacification (PCO) on optical coherence tomography (OCT) acquisition of macular retinal thickness (RT) and volume using time domain OCT (TD-OCT) and spectral domain OCT (SD-OCT). MATERIALS AND METHODS: We studied 37 eyes of 31 patients with PCO. Each patient underwent an evaluation with TD-OCT and with SD-OCT before and after Nd:YAG capsulotomy. We recorded RT and retinal volume in the macular area using only good quality images. RESULTS: Best corrected visual acuity improved in all eyes after Nd:YAG capsulotomy, with the degree of improvement ranging from 0.3 ± 0.7 to 0.1 ±0.7 (p = 0.01). Before the treatment, only 27% of the examinations were valuable with TD-OCT, while using SD-OCT, it was possible to obtain an examination of suitable quality both before and after the Yag laser capsulotomy in 100% of the eyes. We did not observe significant differences between mean preoperative and postoperative RT and total macular volume measurements, neither with TD-OCT nor with SD-OCT. RT and total macular volume values obtained using TD-OCT were always lower than those obtained from the SD-OCT, both before and after capsulotomy. CONCLUSIONS: Our study confirmed that with old generation TD-OCT, PCO has a strong negative influence on the quality of OCT acquisition, and examination is reliable only when it is possible to acquire good quality images. With new generation SD-OCT, tomographic acquisitions are always reliable and are not influenced by the presence of PCO.

Ocular penetration of topical antibiotics: study on the penetration of chloramphenicol, tobramycin and netilmicin into the anterior chamber after topical administration.

BACKGROUND: To compare penetration in the aqueous humour of topically applied antibiotics. DESIGN: Randomized prospective study, Department of Ophthalmology, University of Perugia, Italy PARTICIPANTS: Patients undergoing cataract surgery. METHODS: One hundred twenty-two patients were included: 14 received one drop of chloramphenicol suspension; 12 one application of chloramphenicol gel; 11 one drop of netilmicin suspension; 13 one drop of tobramycin suspension; 37 repeated instillations of chloramphenicol suspension every 10 min for a total of four drops; and 35 repeated instillations of chloramphenicol gel every 10 min for a total of four drops. Samples were taken immediately before surgery from the anterior chamber in order to determine the antibiotic by means of high-performance liquid chromatography. Samples were taken 45-190 min after the eye drops were instilled. MAIN OUTCOME MEASURES: Intraocular penetration of chloramphenicol, netilmicin and tobramicyn. RESULTS: After a single administration, netilmicin and tobramycin were undetectable, whereas the chloramphenicol suspension reached a mean concentration of 0.23 ± 0.21 µg/mL, and the chloramphenicol gel a mean concentration of 0.13 ± 0.14 µg/mL. After repeated administrations, the mean concentrations of the chloramphenicol suspension and gel were 0.60 ± 0.26 µg/mL and 0.58 ± 0.18 µg/mL, respectively. CONCLUSIONS: Tobramycin and netilmicin do not reach detectable concentrations, whereas chloramphenicol, after multiple administrations, reaches concentrations that are effective against Haemophilus influenzae and Haemophilus parainfluenzae, Legionella pneumophila, Moraxella catarrhalis, Neisseria meningitidis, Pasteurella multocida and Streptococcus pneumoniae. This means that chloramphenicol can be rationally used in the prophylaxis and treatment of infections supported by sensitive germs.

Macular thickness measured by optical coherence tomography in a healthy population before and after uncomplicated cataract phacoemulsification surgery.

PURPOSE: To examine macular changes before and after uncomplicated cataract surgery in a healthy population. MATERIAL AND METHODS: In a prospective study, we evaluated 62 eyes of healthy patients having elective cataract phacoemulsification. We performed optical coherence tomography (OCT) measurements preoperatively and at 3, 6, 12, 20, and 28 weeks after surgery. The retinal map was divided into minimal foveal thickness, a central 1-mm disk area, and two peripheral ring areas with diameters of 3 mm and 6 mm, respectively, and centered on the fovea. We compared the postoperative OCT values against the respective preoperative values. RESULTS: Two eyes (3.2%) developed cystoid macular edema (CME) after cataract surgery and were excluded from the study. With respect to preoperative values, visual acuity improved significantly postoperatively, and at 12 weeks, we observed an asymptomatic increase in retinal thickness at 3 mm and 6 mm. Macular volume showed a statistically significant increase at the 12th week after surgery. There was no correlation between macular changes and best corrected visual acuity (BCVA) or ultrasound time. CONCLUSIONS: Our data indicate that the onset of clinically significant CME is rare after uncomplicated phacoemulsification cataract surgery, but with respect to preoperative values we observed an asymptomatic increase in macular thickness and volume at 12 weeks. The possible onset of macular alterations after uncomplicated cataract surgery must be taken into account as a potential later complication, because it can lead to a permanent loss of visual acuity.