Applanation tonometer tip sterilization for adenovirus type 8

Current Trends in Tonometry and Tonometer Tip Disinfection

PRECIS

A survey among members of the American Glaucoma Society (AGS) and the American Optometry Association (AOA) on tonometer preference and tonometer disinfection indicates a shift to disposable tonometer tips compared with 1987.

PURPOSE

This survey's purpose was to determine how eye care providers responded to the 2008 Centers of Disease Control (CDC) tonometer disinfection guidelines, which recommend 10% hypochlorite (dilute bleach) for reusable tonometers. Tonometers measure the eye pressure when they touch the cornea, an essential part of the eye examination.

METHODS

AGS and AOA members were surveyed on tonometer preference, tonometer use, disinfection process, disinfectants, disinfection timing, and tonometer damage.

RESULTS

Survey responses from 79 AOA members and 197 AGS members are included. The Goldmann tonometer is considered most accurate (70, 89% AOA and 161, 82% AGS). It is preferred by 54 (70%) AOA and 193 (98%) AGS members. Many providers (165) use reusable Goldmann tonometer tips (77, 79% AOA, 88, 45% AGS), and most clean with 70% isopropyl alcohol wipes 59 (77%) AOA and 54 (61%) AGS. In summary, 126 of 276 participants (8, 10% AOA and 118, 60% AGS) follow CDC guidelines by using disposable tips (2 AOA and 109 AGS) or disinfecting reusable tips with 10% hypochlorite (6 AOA and 9 AGS).

CONCLUSIONS

The majority of AGS providers follow current CDC tonometer disinfection guidelines by shifting to disposable Goldmann tonometer tips. Only a minority of providers who use reusable tonometer tips disinfect with dilute bleach. Continued education on proper tonometer disinfection is critical to prevent eye-care related infection due to improper disinfection.

Economic and Environmental Impact of Single-use Plastics at a Large Ophthalmology Outpatient Service

PRéCIS:: The use of disposable tonometer prisms and gonioscopy lenses at a large ophthalmology outpatient service incurs significant financial and environmental waste that may not be justified given the limited data surrounding arguments for their use.

PURPOSE

To quantify the economic and environmental burden of single-use plastics from an ophthalmology outpatient service at a large tertiary hospital and describe the relative value and evidence for the safety of disposable versus nondisposable tonometer prisms and gonioscopy lenses.

METHODS

The total number of single-use applanation tonometer prisms and gonioscopy lenses used per year at Boston Medical Center (BMC) was estimated, and the average dollars spent and plastic waste generated in kilograms per year were then determined. These values were compared with the total spending and waste that would be produced if the clinic were to use nondisposable tonometer prisms and gonioscopy lenses exclusively.

RESULTS

Single-use tonometer prisms cost an average of $70,282 per year and produce ~100.8 kg of plastic waste per year at BMC. Single-use gonioscopy lenses cost ~$9,040 per year and produce 8.8 kg of plastic waste per year at BMC. An excess of $65,185 and 109.6 kg of plastic waste could be avoided each year by only using nondisposable tonometer prisms and gonioscopy lenses at the BMC ophthalmology outpatient service.

CONCLUSIONS

Single-use plastics in ophthalmology outpatient services generate significant environmental waste and financial cost compared with nondisposable instruments. This cost may outweigh the benefits of these instruments given the limited data surrounding arguments for their use.

Efficacy and effectiveness of alcohol in the disinfection of semi-critical materials: a systematic review

OBJECTIVE

to assess the efficacy and the effectiveness of 60-80% alcohol (v/v) in the disinfection of semi-critical materials which were either previously cleaned or not.

METHOD

studies obtained from BIREME, IBECS, MEDLINE, ScIELO, PubMed, Ask Medline web portals, and references from other studies. Criteria were created to assess the methodological quality of articles. Out of the 906 studies found, 14 have been included.

RESULTS

after materials were disinfected with alcohol, microorganisms were detected in 104/282 (36.9%) effectiveness tests and in 23/92 (25.0%) efficacy tests that were conducted. In the field studies, disinfection was not achieved for 74/218 (33.9%) of the products that were submitted to previous cleaning and for 30/64 (46.9%) of the ones which were not submitted to previous cleaning. In the experimental studies, alcohol disinfection was not efficacy in 11/30 (36.7%) and 12/62 (19.4%) of products, respectively. The studies were not found to have followed standardized methods.

CONCLUSION

disinfection of semi-critical products with alcohol 70% - or in an approximate concentration - cannot be recommended to all health care products in an unrestricted way. However, according to the type of semi-critical product, disinfection can be attained with or without previous cleaning.

Minimal cross-infection risk through Icare rebound tonometer probes: a useful tool for IOP-screenings in developing countries

AIMS

Recently, a new rebound tonometer has been introduced into the market, which might be useful for glaucoma screenings in developing countries. Disposable probes, that are potentially reusable, are recommended by the manufacturer. Our study aimed to address the question of microbial transmission risks if the probes are reused.

METHODS

IOP measurements were obtained from 100 healthy eyes. The used probes were inoculated on broth and culture media. In addition, 10 probes were analyzed using environmental scanning electron microscopy in saturated hydrogen-steam atmosphere after usage and wipe disinfection technique with Sekusept 4% solution or Isopropanol 70%.

RESULTS

No bacterial or fungal growth could be detected in any of the inoculated agar plates or broth tubes. No microorganisms, clumps of cells, or single intact epithelium cells were detected in any of the probes using environmental scanning electron microscopy. Cell debris was detected on seven probes; three probes were completely free of any residual cell elements.

CONCLUSION

Transmission of possibly infective material through reused probes is significantly less than for reusable Goldmann probes if the same sterilization protocols are applied. Re-usage of the probes appears safe and is helpful in avoiding unnecessary costs.

Efficacy of hospital germicides against adenovirus 8, a common cause of epidemic keratoconjunctivitis in health care facilities

The inactivation of virus-contaminated nonporous inanimate surfaces was investigated using adenovirus type 8, a common cause of epidemic keratoconjunctivitis. A 10-microl inoculum of adenovirus was placed onto each stainless steel disk (1-cm diameter), and the inoculum was allowed to air dry for 40 min. Twenty-one different germicides (including disinfectants and antiseptics) were selected for this study based on their current uses in health care. After a 1- or 5-minute exposure to 50 microl of the germicide, the virus-germicide test mixture was neutralized and assayed for infectivity. Using an efficacy criterion of a 3-log10 reduction in the titer of virus infectivity and regardless of the virus suspending medium (i.e., hard water, sterile water, and hard water with 5% fetal calf serum), only five disinfectants proved to be effective against the test virus at 1 min: 0.55% ortho-phthalaldehyde, 2.4% glutaraldehyde, 2.65% glutaraldehyde, approximately 6,000 ppm chlorine, and approximately 1,900 ppm chlorine. Four other disinfectants showed effectiveness under four of the five testing conditions: 70% ethanol, 65% ethanol with 0.63% quaternary ammonium compound, 79.6% ethanol with 0.1% quaternary ammonium compound, and 0.2% peracetic acid. Of the germicides suitable for use as an antiseptic, 70% ethanol achieved a 3-log10 reduction under four of the five test conditions. These results emphasize the need for proper selection of germicides for use in disinfecting noncritical surfaces and semicritical medical devices, such as applanation tonometers, in order to prevent outbreaks of epidemic keratoconjunctivitis.

Contamination of disposable tonometer prisms during tonometry

AIM

Due to the theoretical possibility of prion transmission in applanation tonometry, many ophthalmological units in the United Kingdom now use disposable tonometer prisms. We have investigated the potential for bacterial and viral transmission from the health practitioner to the patient via disposable prisms.

METHODS

All staff who perform applanation tonometry at the Sussex Eye Hospital (SEH) received a questionnaire to evaluate if the applanating face of the prism is touched during tonometry and the ease of use of the disposable prism compared to the reusable prisms that were previously used. We then cultured prisms handled by a random sample of staff members for common bacteria. Finally, we constructed a model to investigate the possibility of interpatient adenoviral transmission via disposable tonometer prisms.

RESULTS

The questionnaire revealed that almost 50% of the staff admit to touching the applanating face of the tonometer prism prior to applanation. Cultures of the prisms grew a range of bacteria including Staphylococcus epidermidis, Staphylococcus aureus, and Bacillus species. The viral model suggested that adenovirus could be transmitted by applanation tonometry.

CONCLUSION

The use of disposable prisms for applanation tonometry may reduce the risk of prion transmission but is not bacteriologically or virologically aseptic. This is a potential infection risk to patients.

Methods of disinfecting contact lenses to avoid corneal disorders

The contact lens industry has grown rapidly over the past four decades due to the wide-spread demands of the American population for a convenient alternative to spectacle wear for the correction of myopia. Unfortunately, many people who wear contact lenses are not aware of the potential risks associated with them, and consumer education about lens care has not been adequate. This article reviews the role of disinfection in contact lens wear, summarizes the current available contact lens disinfection systems, and provides recommendations for safe contact lens use.

Efficacy of a disinfectant wipe method for the removal of adenovirus 8 from tonometer tips

PURPOSE

To determine the efficacy of a disinfectant wipe method in eliminating adenovirus 8 from both Goldmann tonometer and pneumotonometer tips, and to determine the efficacy of 5-minute disinfectant soaks in removing the virus from Goldmann tonometer tips.

METHOD

Quantification of adenovirus 8 in the ocular secretions of six infected patients was performed. Clinically relevant inocula of adenovirus 8 were then prepared in a serum suspension which was used to contaminate Goldmann tonometer and pneumotonometer tips. Each contaminated tip was subjected to either a dry wipe or a wipe with one of the following: water, isopropyl alcohol, hydrogen peroxide, and iodophor. The tips were than quantitatively assayed for residual adenovirus 8. Disinfectant soaks were similarly assessed using contaminated Goldmann tonometer tips soaked in water, hydrogen peroxide, iodophor, and sodium hypochlorite.

RESULTS

Adenovirus 8 was recovered from both types of tonometer tips after dry wipes, but no viable virus was recovered from tips wiped with water only or with any of the disinfectants tested. Adenovirus 8 also was recovered from Goldmann tonometer tips that were either rinsed or soaked in water; no virus was recovered from tips soaked for 5 minutes in any of the disinfectants tested.

CONCLUSION

A disinfectant wipe method using isopropyl alcohol, hydrogen peroxide, or iodophor is effective in removing adenovirus 8 from both Goldmann tonometer and pneumotonometer tips. Five-minute disinfectant soaks also are effective for Goldmann tonometer tips.

Sources of error with use of Goldmann-type tonometers

There are many sources of error in the use of Goldmann-type applanation tonometers. In clinically normal corneas hypofluorescence of the precorneal tear film, accommodation, the Valsalva maneuver and vertical gaze are preventable causes of large tonometric errors. Repeated tonometry may induce a decline in the intraocular pressure (IOP). Variations in the corneal resistance to indentation between eyes cause significant errors. The most significant cause of error in clinically abnormal eyes is corneal epithelial edema, which causes a marked underestimation of IOP. Measurements obtained with Goldmann-type tonometers can be used with confidence to monitor changes in the IOP of an individual, but should not be relied on to determine the absolute manometric pressure within an eye or to compare the IOPs in eyes of different individuals.

Pneumotonometry using sterile single-use tonometer covers

Current methods for cleaning pneumotonometer tips include soaking the removable tip in various chemical agents. Disadvantages of this technique include the potential for incomplete disinfection, corneal contact with cleaning solutions, tip damage or loss, and soaking time. The authors studied the use of an available, disposable latex cover placed over the pneumotonometer tip for measuring intraocular pressure (IOP) in 46 eyes with normal corneas from a glaucoma screening clinic and 141 eyes with normal and abnormal corneas from a cornea and external disease clinic. The mean absolute IOP difference comparing with and without the tonometer cover was 1.6 mmHg for the glaucoma screening patients and 1.8 mmHg for the cornea clinic patients. A tonographic-like effect due to repeated tonometry also was shown. An additional study measuring a series of known IOP values in a cadaver eye showed no significant difference between uncovered and covered readings. These data suggest that placement of a disposable, latex cover over the pneumotonometer tip enables accurate IOP measurements and is a sanitary and convenient alternative method to repeated chemical disinfection.

Prolonged recoverability of desiccated adenovirus type 19 from various surfaces

Epidemic keratoconjunctivitis is a highly contagious disease whose transmission has been linked to the ophthalmologist's office. The authors studied the ability of adenovirus 19 (ADV 19) to survive on surfaces commonly found in the office setting. An initial in vitro laboratory experiment demonstrated that ADV 19 in a desiccated state could be recovered up to 8 days from paper, and up to 10 days from cloth, metal, and plastic. The amount of recovered ADV 19 was significantly greater (analysis of variance, P less than 0.0001) from nonporous surfaces (plastic, metal) compared with porous surfaces (cloth, paper). A second experiment demonstrated that 35 days was the maximum length of time that desiccated ADV 19 could be recovered from a nonporous surface (plastic). The authors conclude that despite drying, ADV 19 is a hearty virus that remains potentially infectious for a long time on various surfaces that may be found in an ophthalmologist's office.