The Risk of Microbial Keratitis With Newer Contact Lenses

C. Robert Bernardino, MD


November 06, 2008


Microbial keratitis is a rare but serious vision-threatening complication of contact lens wear.[1,2] Risk factors for microbial keratitis include overnight wear of contact lenses and poor contact lens hygiene. However, the advent of newer contact lens materials and wear schedules may have altered the risk of microbial keratitis. The current study analyzed the newer contact lenses to determine the risks for microbial keratitis.

Risk Factors for Microbial Keratitis With Contemporary Contact Lenses: A Case-Control Study

Dart JK, Radford CF, Minassian D, Verma S, Stapleton F
Ophthalmology. 2008;115:1647-1654


A total of 367 cases of proven or presumed microbial keratitis were compared with 1069 hospital-based controls and 639 population-based controls. Compared with subjects wearing regular planned replacement soft contact lenses, those wearing daily disposable lenses had a higher risk for development of microbial keratitis (1.56x relative risk [RR]). Rigid lenses conferred a lower risk for microbial keratitis (0.16x RR). New hydrogel lenses imparted no improvement in risk over standard silicone-based lenses. Although wearers of daily disposable lenses had a higher risk of microbial keratitis, the infections were not as severe compared with those resulting from regular replacement lenses. Overnight wear was a constant risk, regardless of contact lens type (5.4x RR).


This study shows some interesting characteristics of different contact lenses based on the risk of developing microbial keratitis. Contrary to what might be assumed, daily disposable lenses had the higher risk of microbial keratitis, although a less severe type than what resulted from normal schedule lenses. This increase may be due to poor hygiene practices by daily disposable lens users; they may have a false sense of security because the lenses are being disposed anyway. Or it may represent differences in material or lens design. Worse infections in planned replacement lenses are logical, due most likely to poor lens handling and case colonization. It should be noted that the practice that poses the greatest risk for microbial keratitis, overnight wear, was not altered by changes in material and disposal schedules; it was the same across all lens types.



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