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F. Stapleton, T. Naduvilath, Y. Wu, N. Carnt, L. Keay, K. Edwards, A. Ho; The Risk of Vision Loss in Contact Lens Wear and Following LASIK. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1247.
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To estimate the risk of vision loss following contact lens related microbial keratitis and to compare this with a one-off risk of vision loss following contemporary LASIK surgery.
A 12-month national prospective surveillance study identified all new cases of microbial keratitis related to contact lens wear. Controls were generated using a population based telephone survey and the incidence of vision loss of 2 or more lines of best corrected visual acuity was estimated for each lens type and wear modality by wear duration. The risk of vision loss following refractive surgery was also estimated by reviewing available FDA studies evaluating outcomes and safety of LASIK surgery from 2005 onwards. A proportion meta-analysis using Mantel-Haenszel weighting and random effects was used to estimate the rate of vision loss following LASIK.
286 eligible cases were reported during the study period, of which 39 lost vision. 1,122 community controls were identified. The average incidence of vision loss for any contact lens type was 0.6 (95% confidence intervals (CI) 0.5-0.7) per 10,000 wearers per year. The incidence of vision loss was higher during the first 6 months of lens wear 0.8 (95% CI 0.8-0.9) per 10,000 wearers. Vision loss varied with lens modality and type with the greatest vision loss occurring with overnight soft contact lens use in 4.0 (2.9-6.6) per 10,000 wearers per year and least in daily wear soft lens use 0.4 (0.4-0.4) per 10,000 wearers per year. Vision loss following LASIK occurred in 42 (95% CI 20-74) per 10,000 cases. Least-squares fitting of cumulative vision loss (P, per 10,000 wearers) over time (t, in years) was conducted according to an exponential model of the form P=10,000+P0-e-k(t-to); in which k is a time-constant proportional to the incidence, and offset constants t0 and P0 were used to account for the different incidence for the first 6 months of wear. The fitted model was used to predict the number of years of contact lens wear to which the one-off risk associated with a LASIK procedure is equivalent. From this analysis, vision loss with LASIK is equivalent to 69 years (95% CI 43-134) of any contact lens use, 102 years (95% CI 70-179) of daily contact lens use and 10 years (95% CI 7-17) of overnight soft contact lens use.
On average, daily contact lenses need to be worn for a life-time to produce the vision loss rate equivalent to a one-off LASIK procedure. The one-off risk of vision loss with refractive surgery is equivalent to 10 years of overnight soft contact lens use.
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