The importance of the cornea to the ocular structure and visual system is often overlooked because of the cornea's unassuming transparent nature. The cornea lacks the neurobiological sophistication of the retina and the dynamic movement of the lens; yet, without its clarity, the eye would not be able to perform its necessary functions. The complexity of structure and function necessary to maintain such elegant simplicity is the wonder that draws us to one of the most important components of our visual system.

Anatomy and physiology of the cornea

Intraocular Tuberculosis—An Update

Health care-associated infections (HAIs) result in increased patient morbidity and utilization of health care resources. Rates of HAI are increasing despite advances in health care technology. Limited antimicrobial agents and a dry drug pipeline make novel prevention efforts critical. Chlorhexidine, an antiseptic solution that has been used worldwide since the 1950s, is a safe and effective product with broad antiseptic activity. Novel uses of chlorhexidine-containing products are being implemented to promote antisepsis and prevent bacterial colonization and infection. We review some of the many infection control applications of chlorhexidine in the battle against HAI, such as general skin cleansing, skin decolonization, preoperative showering and bathing, vascular catheter site preparation, impregnated catheter site dressings, impregnated catheters, and oral decontamination. As mandatory public reporting and pay for performance force infection control issues to the forefront, chlorhexidine-containing products may provide a vast armamentarium for the control and prevention of HAI.

http://gavecelt.it/nuovo/sites/default/files/uploads/clorexidina_cid.pdf

Chlorhexidine: Expanding the Armamentarium for Infection Control and Prevention

RESULTS: Laser-created capsulotomies were significantly more precise in size and shape than manually created capsulorhexes. In the patient eyes, the deviation from the intended diameter of the resected capsule disk was 29 mm G 26 (SD) for the laser technique and 337 G 258 mm for the manual technique. The mean deviation from circularity was 6% and 20%, respectively. The center of the laser capsulotomies was within 77 G 47 mm of the intended position. All capsulotomies were complete, with no radial nicks or tears. The strength of laser capsulotomies (porcine subgroup) decreased with increasing pulse energy: 152 G 21 mN for 3 mJ, 121 G 16 mN for 6 mJ, and 113 G 23 mN for 10 mJ. The strength of the manual capsulorhexes was 65 G 21 mN. CONCLUSION: The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique. Financial Disclosure: The authors have equity interest in OptiMedica Corp., which manufactures the femtosecond laser cataract system.

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Femtosecond laser capsulotomy.

Effect of cataract surgery on the corneal endothelium: Modern phacoemulsification compared with extracapsular cataract surgery

Purpose To evaluate the effect of the location of the corneoscleral tunnel incision as well as preoperative and intraoperative parameters on total and localized endothelial cell loss Setting Department of Ophthalmology, Humboldt-University of Berlin, Berlin, Germany Methods Fifty consecutive patients scheduled for routine cataract surgery were selected prospectively for this clinical trial Preoperatively, the axial length, anterior chamber depth, lens thickness, and astigmatism were measured Phacoemulsification time and relative energy as well as total surgical time were recorded With a specular microscope, endothelial cell counts were determined centrally, superiorly, and temporally preoperatively and 6 weeks and 6 and 12 months postoperatively Results After 12 months, the mean overall central endothelial cell loss in all eyes was 85% The mean endothelial cell loss was 119% in the lateral quadrant and 114% in the superior quadrant There were no significant differences between superior and temporal surgical approaches in intraoperative parameters of phacoemulsification time, relative intensity of phacoemulsification, and surgical time There were no significant differences in central endothelial cell loss or in the area localized in the quadrant of the positions of the corneal surgical site The only risk factors found significant for higher endothelial cell loss were shorter axial length and longer phacoemulsification time Conclusions The location of corneoscleral incisions for phacoemulsification can be chosen according to the preoperative astigmatism without inducing additional adverse effects on the corneal endothelium Shorter eyes have a significantly higher risk for greater endothelial cell loss

Endothelial cell loss after phacoemulsification: relation to preoperative and intraoperative parameters

A Prospective Evaluation of a Diffractive versus a Refractive Designed Multifocal Intraocular Lens

Objective To characterize possible differences in endothelial cell changes after cataract surgery in patients with pseudoexfoliation syndrome (PSX). Methods In this prospective, age-matched, controlled clinical study, 25 consecutive patients with PSX and 25 control patients with senile cataracts only were studied. All patients were treated with standardized cataract surgery. Sequential quantitative and qualitative morphometric endothelial cell analyses of the central and paracentral cornea were performed preoperatively and postoperatively at 1 day, 4 weeks, and 6 months using noncontact specular microscopy. Results Preoperative endothelial cell counts were 9.9% ( P 2 ) than in controls (2648±349 cells/mm 2 ). The mean endothelial cell loss was 11.1% in the PSX group and 10.3% ( P Conclusions Endothelial cell density is reduced preoperatively in patients with PSX compared with age-matched controls. In patients with PSX, cataract surgery induced similar endothelial cell changes without increased endothelial cell loss postoperatively.

Corneal Endothelial Cell Changes in Pseudoexfoliation Syndrome After Cataract Surgery

• Background: Severe decentration and subluxation of intraocular lenses (IOLs) may lead to double vision, glare and deterioration of vision to the point of functional aphakia. The purpose of the present study was to analyse causes for severe IOL dislocation. • Material and methods: Between January 1989 and January 1996, 37 patients required IOL exchange because of decentrated or subluxated posterior chamber lenses. Twenty-five of the exchanged lenses were implanted in our hospital, 12 lenses elsewhere. After explantation the lenses were examined by light and electron microscopy. • Results: In 10 eyes, asymmetric implantation of the posterior chamber lens was responsible for decentration. Three of the lenser concerned were multifocal IOLs. Asymmetric implantation led to a significantly higher rate of explantations in eyes with multifocal lenses (P<0.005). In five eyes decentration developed due to asymmetric capsular shrinkage, in four eyes due to posterior synechiae. A lens subluxation developed in three eyes as a result of rupture of the posterior capsule and in nine eyes because of zonular defects. In three cases decentrations were induced by an extensive secondary cataract. Macroscopically visible changed geometry of the haptics was found in nine lenses; eight of these had polypropylene haptics. Seven lenses showed severely altered haptics on electron-microscopic examination. In four eyes subluxated lenses had to be explanted together with the capsular bag because of severe defects of the zonula, which caused decentration in nine eyes. • Conclusions: Asymmetric implantation of posterior chamber lenses should be strictly avoided. Multifocal lenses require special attention concerning symmetric capsulorhexis and positioning of their haptics.

Causes of severe decentration and subluxation of intraocular lenses

Purpose: To investigate the influence of incision depth and site on wound strength and postoperative astigmatism. Setting: Virchow Memorial Hospital Eye Clinic, Berlin, Germany. Methods: In this prospective, randomized study, 180 patients with a 7.0 mm tunnel incision were examined. They were divided into the following subgroups: primary incision depth of 300 and 500 [μm; limbal incision and scleral incision; temporal scleral incision and scleral incision at the 12 o'clock position; temporal limbal incision and limbal incision at the 12 o'clock position. Postoperative astigmatism was measured by keratometry and videokeratoscopy 1 day, 1 and 4 weeks, and 8 months postoperatively. Wound strength was measured with an ophthalmodynamometer on the first postoperative day and after 1 week at the site with the least mechanical stability adjacent and posterior to the primary incision. Results: The temporal incision, which was performed 1.0 mm behind the surgical limbus, led to induced astigmatism of 0.65 diopters (D) ± 0.23 (SD) after 8 months. When the incision was at the 12 o'clock position, the induced astigmatism was 0.97 ± 0.41 D. Induced astigmatism was highest following a limbal incision in the 12 o'clock position (1.33 ± 0.63 D). This effect was less pronounced with a temporal incision. Incision depth did not significantly influence induced astigmatism. An incision depth of 500 [Lm led to induced astigmatism of 0.94 ± 0.50 D; a depth of 300 R,m led to induced astigmatism of 0.78 ± 0.64 D. After 1 week, wound strength was highest with temporal scleral incisions (38.6 ± 2.1 kPa by ophthalmodynamometer) and lowest with limbal incisions in the 12 o'clock position (30.8 ± 7.7 kPa). Conclusions: Incision site significantly influenced mechanical wound strength and induced astigmatism; incision depth influenced neither. In general, incisions in the 12 o'clock position induced more astigmatism than temporal incisions.

Norbert Anders

Papers

Endothelial cell loss after phacoemulsification: relation to preoperative and intraoperative parameters

A Prospective Evaluation of a Diffractive versus a Refractive Designed Multifocal Intraocular Lens

Corneal Endothelial Cell Changes in Pseudoexfoliation Syndrome After Cataract Surgery

Causes of severe decentration and subluxation of intraocular lenses

Postoperative astigmatism and relative strength of tunnel incisions: a prospective clinical trial.