Possible adverse effects of drugs used in refractive surgery

Safety of an Intracameral Fixed Combination for Mydriasis and Intraocular Anaesthesia During Cataract Surgery

Purpose

To compare the safety of a standardized, commercially available intracameral combination of mydriatics and anesthetic (ICMA) with a reference topical mydriatic regimen for cataract surgery.

Patients and Methods

The safety results from two international, randomized, controlled clinical studies were combined to compare ICMA at the beginning of cataract surgery (ICMA group) to the reference topical mydriatic regimen (reference group). Data were collected on ocular and systemic adverse events, corneal and anterior chamber examination, endothelial cell density, retinal thickness and visual acuity. Analysis was performed on a pooled safety set from both studies, preoperatively and up to 1 month postoperatively.

Results

342 patients received ICMA and 318 the reference topical regimen. Ocular adverse events were reported in 17.0% of patients in the ICMA group and 18.6% in the reference group. No difference was shown between groups in endothelial cell density (2208 ± 498 cells/mm2 for ICMA group versus 2241 ± 513 cells/mm2 for the reference group; p=0.547) and retinal thickness (change from baseline less than 50 µm in 94.7% versus 95.0% of patients, respectively) at 1 month postoperatively. At 1-day post-surgery, less patients in the ICMA group had moderate or severe (Grades 2 and 3) superficial punctate corneal staining (3.9% versus 7.0% for the reference group; p=0.064). Postoperatively, some ocular symptoms were also less frequently reported in the ICMA group. Best-corrected visual acuity increased in 96.0% of patients in the ICMA group and 95.8% in the reference group at 1 month.

Conclusion

ICMA injection at the beginning of cataract surgery was demonstrated to be safe and may also provide perioperative and postoperative advantages over the standard topical mydriatic regimen.

Effects of Regular/Dilute Proparacaine Anesthetic Eye Drops in Combination with Ophthalmic Antibiotics on Corneal Wound Healing

Purpose: Topical, local anesthetic eye drops in conjunction with antibiotics are commonly used to reduce ocular pain and treat patients in emergency clinics; however, their effects on corneal healing are poorly understood. This study examined whether regular or diluted proparacaine eye drops given in combination with common ophthalmic antibiotics affect corneal wound healing parameters using in vitro and in vivo models. Methods: Primary human corneal fibroblasts generated from donor corneas and New Zealand white rabbits were used. Regular (0.5%) and diluted (0.05%) proparacaine eye drops, twice daily for 3 days, were applied to cultures and rabbit eyes, with or without ophthalmic antibiotics (polymyxin B sulfate and trimethoprim). Trypan blue, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), and scratch wound assays measured cellular viability, proliferation, and migration, respectively, in vitro. Slit lamp biomicroscopy, tonometry, fluorescein eye test, hematoxylin and eosin (H&E) staining, and 4',6-diamidino-2-phenylindole (DAPI) immunofluorescence were used for in vivo studies. Results: Both regular and diluted proparacaine affected wound healing response in the cornea in vitro and in vivo in a time-dependent manner. Adjunct antibiotic treatments had additive effects characterized by reduced corneal fibroblast viability, proliferation, and migration in vitro and corneal epithelial recovery in vivo. Regular proparacaine with antibiotics showed most pronounced effects on corneal wound healing parameters, and diluted proparacaine without antibiotics had minimal negative effects in vitro and in vivo. Conclusions: Both methods of regular (0.5%) and diluted (0.05%) proparacaine topical application to the cornea are safe, but impede corneal wound healing in vitro and in vivo. Adjunct antibiotic treatments had additive negative effects on corneal wound repair.

Co-operative inhibitory effects of hydrogen peroxide and iodine against bacterial and yeast species

BACKGROUND

Hydrogen peroxide and iodine are powerful antimicrobials widely used as antiseptics and disinfectants. Their antimicrobial properties are known to be enhanced by combining them with other compounds. We studied co-operative inhibitory activities (synergism, additive effects and modes of growth inhibition) of hydrogen peroxide and iodine used concurrently against 3 bacterial and 16 yeast species.

RESULTS

Synergistic or additive inhibitory effects were shown for hydrogen peroxide and iodine mixtures against all 19 species used in the study. Both biocides were mostly cidal individually and in mixtures against Pseudomonas aeruginosa and Staphylococcus aureus. Both compounds manifested static inhibitory effects individually, but their mixtures were synergistically cidal for Saccharomyces cerevisiae and Escherihia coli. Cells of S. cerevisiae treated with hydrogen peroxide and iodine-hydrogen peroxide mixture produced increased numbers of respiratory deficient mutants indicating genotoxic effects.

CONCLUSION

Iodine and hydrogen peroxide used concurrently interact synergistically or additively against a range of prokaryotic and eukaryotic microorganisms. The study provides an insight as to how these traditional antimicrobials could be used more effectively for disinfection and antisepsis. In addition, a simple approach is proposed for scoring genotoxicity of different biocides by using the budding yeast system.

The inhibitory effect of different concentrations of topical bevacizumab on corneal neovascularization

PURPOSE

This study aimed to evaluate the effects of different concentrations of topically administered bevacizumab (Avastin) on experimental corneal neovascularization (NV) in rats.

METHODS

  Corneal NV was induced by chemical cauterization with silver nitrate sticks applied to the centre of the corneas of 37 Wistar rats. The rats were then randomized to four topical treatment groups: group 1 (n = 10) received 4 mg/ml bevacizumab; group 2 (n = 9) received 2 mg/ml bevacizumab; group 3 (n = 10) received 1 mg/ml bevacizumab, and group 4 (n=8) represented a control group and received saline. All drops were initiated immediately after cauterization and applied twice per day for 7 days. Corneal NV was assessed 8 days after cauterization in a masked fashion, both qualitatively by clinical evaluation and quantitatively by blood vessel count in photographs of histological sections.

RESULTS

 On clinical evaluation, groups 1 and 2 showed significantly less NV compared with the saline-treated control group (p = 0.006 and p = 0.024, respectively). Histopathological evaluation showed that only group 1 differed significantly from controls (5% significance level) and normal corneal epithelium was seen in all groups.

CONCLUSIONS

  Topically administered bevacizumab at a concentration of 4 mg/ml significantly reduces corneal NV according to both clinical and histopathological evaluations; lower concentrations were less effective on both parameters. No corneal epitheliopathy was found using these concentrations.

Local anesthesia for cataract surgery

Various aspects of local anesthesia for cataract surgery, such as the anesthetic agents and their interaction with ocular nerve supply, anesthesia requirements, available clinical techniques and their inherent complications are reviewed. A comparative evaluation of clinical techniques in terms of efficacy, akinesia, and patient-perceived pain during both anesthesia administration and intraoperative cataract surgery is presented, along with the prevailing practice patterns of anesthesia techniques among refractive surgeons in the United Kingdom and United States. More randomized clinical trials are needed to facilitate statistical methods of metaanalysis to establish convincingly the overall benefits and efficacy of the various local anesthesia procedures in cataract surgery. The wide scope of the present review is of relevance in structuring ophthalmology and anesthesia specialist training programs for junior staff.

Corneal toxicity from topical ocular and systemic medications

PURPOSE

To review what is known about the adverse effects on the cornea from various classes of medications. New data from previously unreported cases of drug-related corneal toxicity are included.

METHODS

Data are garnered from a Medline literature review and from case reports collected by the World Health Organization, the Food and Drug Administration, and the National Registry of Drug-Induced Ocular Side Effects.

RESULTS

Aminoglycosides, bisphosphonates, chemotherapeutic medications, cyclooxygenase-2 inhibitors, fluoroquinolones, glaucoma eye drops, topical iodine, nonsteroidal anti-inflammatory eye drops, preservatives in eye drops, retinoids, topical anesthetics, topical steroids, and some herbal medications can cause corneal toxicity in some patients.

CONCLUSION

Ophthalmologists need to be aware of potential corneal toxicities that can arise from commonly prescribed medications.