Keratoreformation by contact lenses after radial keratotomy: a re-analysis.
A recent paper analysed change in refraction and corneal curvature associated with contact lens wear in patients who had had radial keratotomy at least a year beforehand. Conventional methods of analysis were used. This paper applies methods that have only recently become available. The results are clearer and less ambiguous. Formally, the analysis shows that there are significant mean changes in refraction (estimated to be +1.69/-0.50 x 105) and corneal power (-0.66/-0.25 x 155). In spite of the difference between these two mean changes, the analysis shows that the change in refraction may be associated with change in the corneal power alone. There is no reason to believe that any other change is occurring in the eye. Care needs to be executed in assigning a causative role to contact lenses in changing refraction and corneal curvature. Almost certainly the lenses do have such a role but the analysis does not formally allow an unequivocal conclusion concerning that role.
Harris
W F
WF
Department of Optometry, Rand Afrikaans University, Johannesburg, South Africa.
Malan
D J
DJ
Astin
C L
CL
D000886:Anthropometry; D003261:Contact Lenses; D003315:Cornea / Q000033:anatomy & histology*; D006801:Humans; D007646:Keratotomy, Radial; D012029:Refraction, Ocular; D013997:Time Factors