Microbial Contamination of Rigid Gas Permeable (RGP) Trial Lenses and Lens Cases in China

The efficacy of a device-based approach to microorganism disinfection and protein removal for orthokeratology lenses in varied clinical circumstances

PURPOSE

RigidCare is an electrolysis-based device that recently obtained approval from the US's FDA to sterilise microorganisms and remove proteins for orthokeratology (O-K) lenses. The study was conducted to investigate the device's performance in varied clinical circumstances.

METHODS

Trial lenses and private lenses were employed by O-K lens wearers from five hospitals for an evaluation of disinfection and sterilisation and an assessment of protein removal, respectively. Menicon multipurpose solution and protein remover were selected for use with the control group. Following the instructions, pre-cleaning lens samples, post-cleaning lens samples and residual solution samples of trial lenses of the experimental and control groups were collected for microorganism examinations by an experienced third-party testing organisation. The levels of protein deposition for these two approaches were rated by senior O-K experts. Categorical variables were analysed using statistical tests, such as the chi-squared test and Fisher's exact test.

RESULTS

The microbial positive rate detected from the pre-cleaning and post-cleaning lens samples and the residual solution of the trial lenses for the experimental and control group was 4/76 vs 1/74 (P = 0.37), 1/76 vs 0/74 (P = 1.00) and 0/76 vs 8/74 (P = 0.006), respectively. Following protein removal, the experimental group exhibited a significantly higher overall proportion of lenses rated as 'clean' or with a 'mild deposit' (96.4 %, 79/82) compared to the control group (85.7 %, 66/77), with a significant difference (P < 0.05).

CONCLUSION

This multi-center study demonstrated that RigidCare exhibited superior efficacy in disinfection, sterilisation and protein removal as compared to Menicon multipurpose solution and protein remover.

[Effect of conventional and orthokeratological hard contact lenses on anatomical and functional characteristics of the cornea]

Contact lenses are widely used for correction of myopia due to their accessibility, effectiveness and relative safety.

PURPOSE

This study evaluated the potential effects of conventional hard contact lenses (HCL) and orthokeratological contact lenses (OKL) on anatomical and functional condition of the cornea in myopia correction.

MATERIAL AND METHODS

The study included 80 patients (159 eyes) with low, moderate and high myopia. Group 1 consisted of 40 patients (79 eyes) who used conventional HCL; group 2 included 40 patients (80 eyes) who used OKL. All patients underwent topographic keratometry, corneal pachymetry mapping (Pentacam, Oculus, Germany; Visante OCT, Carl Zeiss, Germany), high-order aberrometry (OPD Scan, Nidek, Japan), confocal microscopy (Confoscan 4, Nidek, Japan), evaluation of corneal biomechanical properties (ORA, Reichert Technologies, USA) and corneal light scattering (Pentacam, Oculus, Germany). Examinations were taken before the treatment started and after 8-12 months of contact lens wear.

RESULTS

Group 1 showed corneal thickness increase in all zones (by 0.9-1.1%), no significant changes in corneal refraction, and increase in corneal hysteresis and corneal resistance factor. OKL wear led to a significant flattening of anterior surface of the cornea and steepening of its paracentral area, decrease in central corneal thickness (by 2.8%) and increase in mid-peripheral thickness (by 2.2%). No significant changes in posterior corneal surface were observed in the study patients. More significant increase in higher-order aberrations and the degree of light scattering was observed in group 2, while changes in subepithelial nerve plexus and stromal structure were more significant in group 1.

CONCLUSION

Long-term OKL wear shows more significant morphological and functional corneal changes compared to RGP lens.

Clinical effect of rigid gas permeable (RGP) contact lens in improving vision and controlling myopia progression of unilateral high myopic children

BACKGROUND

The aim of this study was to explore the clinical effect of the RGP contact lens in improving vision and controlling myopia progression of the unilateral high myopic children.

METHODS

In this retrospective analysis case series study, we analyzed the clinical data for 23 subjects with unilateral high myopic children under 6 years old, with the spherical equivalent refractive error of the myopic eye from -5.0 D to -12.0 D, who were enrolled from the outpatient clinic at Beijing Tongren Hospital, China. Fourteen subjects could successfully fit the RGP contact lens, and nine subjects used the spectacle lens. Complete ocular examination was performed at the first visit at the clinic and every three months during the follow-up period.

RESULTS

In the RGP group, the change of axial length (AL) of the high myopic eye was from 25.62 ± 1.31 mm to 25.69 ± 1.31 mm after 12 months. The change of spherical equivalent (SE) was from -8.73 ± 2.54 D to -8.48 ± 2.77 D. The best corrected visual acuity (BCVA) improved from 0.24 ± 0.18 to 0.78 ± 0.26. In the spectacle group, the change of AL was from 24.76 ± 0.56 mm to 24.94 ± 0.71 mm. The change of SE was from -6.16 ± 2.86 D to -9.45 ± 2.06 D. The improvement of BCVA was from 0.52 ± 0.15 to 0.72 ± 0.23.

CONCLUSIONS

Wearing RGP lens in the children with unilateral high myopia is a safe, convenient and effective method to improve the best corrected vision and controlling myopia progression.

Antimicrobial Efficacy of an Ultraviolet-C Device against Microorganisms Related to Contact Lens Adverse Events

The purpose of the study was to assess the antimicrobial activity of an ultraviolet-C (UVC) device against microorganisms implicated in contact lens related adverse events. An UVC device with an emitting 4.5 mm diameter Light Emitting Diode (LED; 265 nm; 1.93 mJ/cm2) was used. Pseudomonas aeruginosa, Staphylococcus aureus, Fusarium solani, and Candida albicans agar plate lawns were exposed to the device beams for 15 and 30 s at 8 mm distance. Following the exposure, the diameter of the growth inhibition zone was recorded. Contact lenses made of Delfilicon-A, Senofilicon-A, Comfilicon-A, Balafilicon-A, Samfilicon-A and Omafilicon-A and a commercially available contact storage case was used. They were exposed to bacterial and fungal strains for 18 h at 37 °C and 25 °C respectively. After this, the samples were exposed to UVC for 30 s at 8 mm distance to determine the antimicrobial efficacy. Samples were then gently washed and plated on appropriate agar for enumeration of colonies. The UVC exposure reduced microbial growth by 100% in agar lawns, and significantly (p < 0.05) reduced microbial contamination to contact lenses and cases, ranging between 0.90 to 4.6 log. Very short UVC exposure has high antimicrobial efficacy against most of the predominant causative microorganisms implicated in contact lens related keratitis. UVC could be readily used as a broad-spectrum antimicrobial treatment for lens disinfection.