Evaluation of the effects on conjunctival tissues of Optive eyedrops over one month usage.

The objective was to compare the effect on conjunctival tissues of the repeated use, over a one-month period, of Optive compared to Hylocomod eyedrops by a population of dry eye sufferers. The rationale for the study was that among dry eye sufferers who attend eye care practices for symptomatic relief, a large number present with conjunctival anomalies evidenced by tissue staining and that conjunctival recovery is essential to their successful long term management. The hypothesis tested was that the decrease in conjunctival staining with Optive is at least as good, and possibly greater, than that with Hylocomod. The cohort population was made up of 47 subjects (11 male and 26 female) aged 42+/-16 years with at least mild dry eye symptoms and conjunctival and/or corneal staining. The population included contact lens wearers (n=26) and non-wearers (n=21). The subjects were randomly allocated to use one of the two study products; they were instructed to use the products as often as needed but at least three times a day. Conjunctival staining was rated on forced choice scales and measured objectively using digital photographs and image analysis. The findings showed that, whereas the staining at the start of the investigation was similar (p=0.318-0.664), staining after one month of use was significantly less with Optive than Hylocomod (p=0.028-0.002). The results demonstrated that the regular use of Optive over one month was significantly superior to Hylocomod in improving conjunctival status by producing a greater reduction in the staining of dry eye sufferers.

Influence of contact lens material surface characteristics and replacement frequency on protein and lipid deposition.

The aim of the study was to quantify the influence of both contact lens material and replacement frequency on protein and lipid deposition. The following hypotheses were tested: (1) both protein and lipid interaction with contact lenses are material-dependent, and (2) the key factors are the material ionicity for the protein deposition and the material chemical composition for the lipid deposition. Three high water content contact lens materials were tested: netrafilcon A (FDA group II, Gentle Touch), etafilcon A (FDA group IV, Acuvue), and vifilcon A (FDA group IV, Focus). Contact lens spoilation was analyzed using ultraviolet spectroscopy and fluorescence spectrophotometry. The results showed that (1) significantly more proteins were deposited on the ionic materials than on the nonionic materials, and that among the ionic materials, the higher the ionicity, the higher the level of protein deposition; (2) there were significantly more surface proteins on the ionic materials after 3 months than after 1 month of wear, but no difference over time was demonstrated for the nonionic materials; and (3) significantly more lipids were deposited onto the surface of vifilcon A than etafilcon A or netrafilcon A, and the presence of vinylpyrrolidone in the vifilcon A formulation was thought to be the cause of increased deposition. The protein and lipid interactions with contact lenses were found to be material- and time-dependent. Protein attraction was found to be related to the material ionicity. The presence of vinylpyrrolidone was a key factor in the attraction of lipids.

Preocular tear film characteristics of nonwearers and soft contact lens wearers.

The aims of the current investigation were to: (1) characterize (structure, volume, and stability) the preocular tear film of contact lens wearers and nonwearers and (2) test for any difference between contact lens wearers and nonwearers and between symptomatic and asymptomatic subjects. The tear film structure and stability were tested using the Tearscope in conjunction with the biomicroscope observation system. The tear prism height, which is indicative of the tear volume, was measured with the slitlamp. The study was carried out on 239 subjects (478 eyes) who attended our clinic for contact lens fitting. Of these, 184 were habitual daily soft contact lens wearers who had not been wearing contact lenses for at least 24 h; the other 55 were noncontact lens wearers. The results obtained showed that: (1) the stability of the tear film was correlated for two eyes of the same subject; (2) the structure, volume, and stability of the preocular tear film were similar for both groups; (3) no difference in tear film stability was found between asymptomatic and symptomatic contact lens wearers, but a significant difference was found between asymptomatic and symptomatic noncontact tact wearers; and (4) the stability of the tear film was influenced by the nature of the lipid layer present at the surface of the aqueous layer; the greatest stability was achieved when the lipid layer was thick and homogeneous (amorphous pattern).

Effect of material ionicity on the performance of daily disposable contact lenses.

The surface of hydrophilic contact lenses is intrinsically hydrophobic. Biocompatibility requires the contact lens surface to be coated with a lipoproteinic biofilm produced by the ocular secretion. For daily disposable modality of wear it is essential that biocompatibility, clinically represented by good in vivo wettability and subjective acceptance, is achieved as quickly as possible following insertion, as the process needs to be repeated daily. It has been hypothesised that non-ionic materials will not achieve biocompatibility as rapidly as ionic materials owing to the latter's ability to attract high levels of adsorbed proteins. The current investigation was a double-masked crossover study that evaluated, over 1 week of wear, a new non-ionic material (Nelfilcon A) and a current ionic material (Etafilcon A) under daily disposable modality. The results obtained showed that overall, both contact lens materials achieved good in vivo tear stability over the first 30 min of wear and good subjective acceptance that remained stable over the period of wear. The results obtained demonstrate that a non-ionic material can achieve rapid biocompatibility and subjective acceptance in a similar manner to an ionic material.