The ocular response to extended wear of a high Dk silicone hydrogel contact lens

Abstract

Purpose: A four-month extended wear clinical trial was conducted to compare the ocular effects of a high Dk Balafilcon A silicone hydrogel lens and a low Dk HEMA 38.6 per cent H, O soft lens. Method Twenty-four subjects who were adapted to daily wear of soft lenses wore a high Dk lens in one eye and a low Dk HEMA lens in the other eye for four months on an extended wear basis after one week of daily wear. Thirteen progress evaluations were conducted using standard clinical procedures.Results: Eighteen subjects (75 per cent) completed the study. The high Dk lens induced significantly less bulbar and limbal injection and corneal vascularisation than the low Dk HEMA lens (p < 0.05). Epithelial microcysts were observed only in the eyes wearing the low Dk lens. A significant increase in myopia was found in the eyes wearing the low Dk HEMA lens (mean = 0.50 D, p < 0.01) compared to the insignificant myopic increase of 0.06 D in the eyes wearing the high Dk lens. Three subjects developed small infiltrates in the high Dk lens wearing eyes and significantly more post-lens debris was observed under the high Dk lens. Six subjects developed papillary conjunctivitis in the eye wearing silicone hydrogel lenses but only two of those were discontinued from the study. Conclusion:No hypoxia-related effects were observed with extended wear of the high Dk Balafilcon A silicone hydrogel lens.

Conjunctival redness

“…Numerous authors [10][11][12] have reported that silicone-hydrogel lenses worn on an extended wear basis induced significantly lower grades of conjunctival redness compared to those observed with hydrogel extended wear lenses. Morgan and Efron 13 also demonstrated that silicone-hydrogel lenses worn on an extended wear basis induce relatively low grades of conjunctival redness (between 0.4 and 0.6).…”

“…As discussed above, silicone hydrogel lenses induce minimal amounts of conjunctival redness. [10][11][12] Alteration to care systems…”

Papillary conjunctivitis

“…Grant et al 9 reported that the incidence of CLPC in patients wearing rigid lenses on an extended wear basis was 2%, versus 6-12% for hydrogel disposable extended wear. Fonn et al 15 reported the results of a 4-month clinical trial in which six out of 18 patients (33%) wearing silicone hydrogel lenses on an extended wear basis developed CLPC; two of these patients were discontinued from the study because of the severity of the condition.…”

A survey of corneal changes caused by daily wear silicone hydrogel contact lenses

“…Thus, they protect the cornea from the hypoxia caused changes. [11][12][13][14] Furthermore, Santos et al have proven that SiH contact lenses are generally less susceptible to microbial adhesion, in comparison to conventional hydrogels. This feature facilitates better lens resistance to bacteria.…”