Pilot Study to Determine the Effect of Lens and Eye Rinsing on Solution-Induced Corneal Staining (SICS)

Polyhexamethylene biguanide hydrochloride (PHMB)-properties and application of an antiseptic agent. A narrative review

The prevention and management of ocular surface infections is still one of the great challenges for ophthalmologists. The spread of antimicrobial resistance makes it necessary to use antiseptic substances with a broad antimicrobial spectrum. Polyhexamethylene biguanide hydrochloride (Polyhexanide, PHMB) is a broad-spectrum antiseptic with excellent tolerance and a low-risk profile. Its physicochemical action on the phospholipid membrane and DNA replication or repair mechanism, prevents or impedes the development of resistant bacterial strains. PHMB revealed its effective against numerous organisms like viruses, Gram-negative and Gram-positive bacteria, and fungi. Polyhexanide is commonly used as preservative in commercially available disinfecting solutions for contact lens care and in ophthalmic formulations at different concentrations ranging from 1 µg/ml to 50 µg/ml. The administration of 0.02% (200 µg/ml) PHMB is often the first-line therapy of Acanthamoeba keratitis. However, to date, only one close-out randomized controlled study tested the efficacy of 0.02% PHMB in Acanthamoeba keratitis and a phase III study is still ongoing. This paper reviews the antiseptic agent PHMB, focusing on biochemical mechanisms, safety profile and applications in ophthalmology.

Effect of povidone iodine contact lens disinfecting solution on orthokeratology lens and lens case contamination and organisms in the microbiome of the conjunctiva

PURPOSE

To compare lens cleaning routines using a povidone iodine-based rigid lens disinfecting solution and its effect on conjunctival colonisation, and lens and lens case contamination.

METHODS

Participants, aged 6-10 years, receiving orthokeratology treatment were randomised to four lens cleaning routines: with and without the use of daily and/or weekly cleaners, which were performed by their parents. Conjunctival colonisation was compared before lens wear and at 1-, 3-, and 6-month after commencement of lens wear. Contamination of lenses and lens cases was investigated at these times. Organisms were identified using MALDI-TOF mass spectrometry.

RESULTS

Of the 76 participants who completed the study, conjunctival colonization was present in 24 (32 %) at baseline. Of the remaining 52 participants, 34 consistently yielded no growth. Participants positive at baseline were statistically more likely to be colonized after commencement of lens wear (p = 0.020). Overall, colonization rate was reduced to 15 % (11/72) after 6-month lens wear, which reached significance for initially colonized participants (p < 0.001). Few cultures yielded potential ocular pathogens, with notably no Pseudomonas aeruginosa. Contamination rates of both lenses and lens cases were also low, with few isolations of ocular pathogens. No significant differences were observed between cleaning regimes for conjunctival colonization or contamination of lenses or cases.

CONCLUSIONS

Disinfection for rigid and ortho-k lens wearers may be effectively achieved with the use of povidone iodine-based solution, apparently regardless of cleaning routine adopted in the current study. The absence of pathogens in the conjunctiva, lenses, and lens cases in the great majority of samples indicates that it can improve the safety of overnight lens wear.

Ocular surface response and subjective symptoms associated to lens care solutions in Palestine

PURPOSE

To compare the biocompatibility and subjective symptoms of four multipurpose solutions marketed in Palestine with hydrogel contact lenses.

METHODS

50 habitual soft contact lens wearers were recruited in this interventional crossover study. Subjects were asked to attend the optometry clinic five times. A new pair of hydrogel lenses (Bioxifilcon-B) were fitted each time. This pair was soaked randomly overnight in one of the following four-multipurpose solutions (NEOPLUS®, AvizorUnicaSensitive®, ReNuMultiPlus® and COMPLETERevitaLens®) which contain different disinfecting agents (PHMB, Phx, PAPB, and PQ-1+Alexidine, respectively), or non-preserved saline. At each visit, corneal staining, ocular redness and subjective symptoms were assessed.

RESULTS

The percentage of corneal staining increased significantly (P≤0.050) after soaking the lenses with PHMB (86%), PAPB (64%) and Phx (32%) based-solutions. However, a non-significant increase was noticed after the use of PQ-1+Alexidine based solution (30%, P=0.083). Ocular redness evaluation showed a significant increase (P≤0.050) in limbal hyperemia after the use of all solutions, while bulbar redness was significantly increased after the use of biguanide-based solutions (P≤0.050). The subjective assessment analysis showed a non-significant change in comfort, dryness, photophobia and scratchiness (P≥0.050) at 2-h intervention using all solutions, except for the PHMB based solution which showed a significant change in subjective symptoms (P≤0.050).

CONCLUSION

The combination of Bioxifilcon-B hydrogel contact lenses and solution containing PHMB, PAPB and Phx-disinfectants induced a significant increase in corneal staining after 2h of CL-wear with a higher severity when the PHMB-based solution was used, while the PQ-1+Alexidine-based solution did not. Only the PHMB-based solution triggered a significant change in subjective symptoms which might which suggests that it might be related to the severity of staining rather than the induction of staining.

The use of preservatives in dry eye drops

Topical ocular preparations are widely recommended by health care professionals, or chosen by patients, to help manage dry eye disease (DED). The chronic and progressive nature of DED may result in the administration of topical products several times a day, over a period of many years. Given DED is a condition that by definition affects the ocular surface, it is important to understand how the repeated use of eye drops may impact the ocular surface, influence clinical signs, affect symptoms, and impact the overall disease process of dry eye. The component in topical preparations with the greatest potential to adversely affect the ocular surface is the preservative. This paper reviews the literature in relation to the use of preservatives in formulations for dry eye. The ocular effects of benzalkonium chloride (BAK) are summarised and compared to the performance of alternative preservatives and preservative-free formulations. Use of preserved and preservative-free drops in relation to the management of varying stages of DED is discussed.

A novel scale for describing corneal staining

The assessment of corneal staining is a commonly conducted procedure in both clinical practice and as part of various research studies. Different grading scales are employed by many clinicians and researchers to undertake this procedure for corneal staining comparisons between eyes, products and over time. This paper describes the development and use of a grading scale for corneal staining undertaken at an academic research site. The scale involves assessment of three factors across five corneal zones: type, area and depth. Staining type and area are graded on a 0–100 scale, and depth is graded on a 0–4 scale. These factors can be combined to create a three- or two-factor staining grade, or the factors may be reported individually. An additional benefit of this scale is that the staining scores may be reported by zone as “zone staining scores” or the scores of zones may be combined to provide an overall corneal “global staining score”.