Refractive and biometric changes with silicone hydrogel contact lenses.
OBJECTIVE
This study reports data from an 18-month longitudinal study of neophyte contact lens wearers and compares changes in ocular refraction and biometry induced by daily wear and continuous wear of two different silicone hydrogel (SiH) materials.


METHODS
Forty-five subjects were enrolled in the study and randomly assigned to wear one of the two silicone hydrogel materials: Lotrafilcon A or Balafilcon A lenses on either a daily or continuous wear basis. Measurements of objective refraction, axial length, anterior chamber depth, corneal curvature, and the rate of peripheral corneal flattening were performed before and 1, 3, 6, 12, and 18 months after initial fitting.


RESULTS
Mean spherical equivalent refractive error increased in the myopic direction in all contact lens groups across time (p < 0.001). Axial length was the main biometric contributor to the development of myopia. After 18 months of lens wear, subjects in the Lotrafilcon A group showed the greater mean increase in myopia (i.e., -0.50 D).


CONCLUSIONS
The results of this study show that increases in myopia, similar if not higher than those found to occur normally in young adult noncontact lens wearers, still occur with silicone hydrogel contact lens wear. The main biometric contributor to the progression of myopia was an increase in axial length. Differences between our results and those of previous studies with silicone hydrogel contact lenses could be attributed to the differing populations used in which both age and occupation may have played a role.
School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK. jsantodo@hotmail.com
Jacinto
J
Santodomingo-Rubido
Bernard
B
Gilmartin
James
J
Wolffsohn
D000328:Adult; D000867:Anterior Chamber / Q000473:pathology; D001699:Biometry; D003261:Contact Lenses / Q000009:adverse effects*; D003262:Contact Lenses, Extended-Wear; D003315:Cornea / Q000473:pathology; D019781:Corneal Topography; D018450:Disease Progression; D005260:Female; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D008137:Longitudinal Studies; D008297:Male; D009216:Myopia / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy*; D012029:Refraction, Ocular; D012828:Silicones; D011795:Surveys and Questionnaires; D005466:Fluorocarbons
D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D012828:Silicones; C481129:lotrafilcon A; D005466:Fluorocarbons