title: Incidence and morbidity of hospital-presenting corneal infiltrative events associated with contact lens wear.
abstract: OBJECTIVE
  To determine the incidence and morbidity (visual loss) of hospital-presenting corneal infiltrative events (CIEs) associated with the wearing of current generation contact lenses.
  
  
  METHODS
  All contact lens wearers presenting with any form of corneal infiltrate/ulcer to a hospital centre in Manchester, UK, were surveyed in this 12-month, prospective, hospital-based epidemiological study. A clinical severity matrix was used to quantify the overall severity of presenting signs and symptoms. The size of the hospital catchment population and the wearing modalities (daily wear [DW] or extended wear [EW]) and lens types used in that population were estimated from relevant demographic and market data to facilitate the calculation of incidence. We also attempted to ascertain, from their eye care practitioners, the visual acuity (VA) of patients suffering from CIEs prior to and at about six months following attendance at the hospital.
  
  
  RESULTS
  During the survey period, 118 patients presented with CIEs of varying severity. The annual incidence (cases per 10,000 wearers) for all wearing modalities and lens types is 21.3 (95 per cent confidence interval 17.8 to 25.5). The incidence of CIEs for each wearing modality and lens type is: DW rigid, 8.6 (3.9 to 18.7); DW hydrogel daily disposable, 14.0 (9.3 to 21.0); DW hydrogel (excluding daily disposable), 20.4 (15.9 to 26.2); DW silicone hydrogel, 55.9 (9.9 to 309.6); EW rigid, zero (0.0 to 1758.8); EW hydrogel, 144.6 (66.4 to 311.8) and EW silicone hydrogel, 118.6 (75.2 to 186.7). The risk of developing a CIE with EW lenses was 8.1 (5.3 to 12.5) times greater than that with DW lenses (p < 0.0001). Although there was no difference between EW hydrogel and EW silicone hydrogel lenses with respect to the risk of developing CIEs, the clinical severity of CIEs was greater with EW hydrogel lenses (p = 0.04). Results of VA for pre- and post-hospital attendance were obtained from 38 patients, none of whom lost more than one line of VA. For the study population, zero patients (95 per cent CI: 0 to 9.2 per cent) suffered a significant loss of VA as a result of developing a CIE.
  
  
  CONCLUSIONS
  Overall, there is an eight times higher incidence of CIEs in wearers who sleep in contact lenses compared with wearers who use lenses only during the waking hours. For those who choose to routinely or intermittently sleep in soft contact lenses, silicone hydrogels are the lens of first choice because CIEs are less clinically severe with this lens type compared with hydrogel lenses. The rate of significant visual loss as a result of developing a CIE is low.
authors.affiliation: The University of Manchester, PO Box 88, Manchester M60 1QD, UNITED KINGDOM. n.efron@manchester.ac.uk
authors.forename: Nathan
authors.initials: N
authors.lastname: Efron
authors.forename: Philip B
authors.initials: PB
authors.lastname: Morgan
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Hill
authors.forename: Mathew K
authors.initials: MK
authors.lastname: Raynor
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Tullo
mesh_terms: D003261:Contact Lenses / Q000009:adverse effects* / Q000706:statistics & numerical data; D003320:Corneal Ulcer / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D015994:Incidence; D009017:Morbidity; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D006113:United Kingdom / Q000453:epidemiology