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Use of imposed myopic defocus to control the progression of myopia
Author(s) -
MORGAN IG
Publication year - 2008
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2008.5115.x
Subject(s) - medicine , optometry , ophthalmology , monocular , retinoscopy , refractive error , eye disease , computer science , artificial intelligence
Purpose Animal studies suggest that axial elongation of the eye is controlled by pathways that detect hyperopic defocus (growth‐promoting) and others that detect myopic defocus (growth‐inhibiting). The inhibitory pathways generate more powerful signals, and brief periods of imposed myopic defocus block the axial elongation induced by otherwise constant hyperopic defocus. An intervention to prevent myopic progression based on these findings was trialled in a Sydney paediatric ophthalmology practice. Methods The study was approved by the ANU Human Ethics Committee. Informed consent was obtained from the parents of 30 progressing myopes. Participants removed their corrections for 30 minutes per day, replacing them with +3D glasses. During this period, they were encouraged to avoid nearwork. Participants were followed for two years, with initial and final cycloplegic retinoscopy, and subjective refraction and axial length measured at 4 monthly intervals. Results Complete data was obtained for 20 participants. In 13 cases, there was sufficient pre‐trial data on subjective refractions to compare pre‐trial progression with progression during the trial. Of the 26 eyes available for this analysis, progression was reduced by over 80‐100% in 7 eyes, by 60‐80% in 7 eyes, by 40‐60% in 5 eyes, by 20‐40% in 1 eye, and by less than 20% in 6 eyes. In 16/26 eyes, the estimated reduction in progression was at least 1D over the two years. Conclusion These results are consistent with other data on the impact of imposed myopic defocus in humans. However, an RCT in Singapore using monocular rather than binocular treatment has given negative results. A school‐based trial of binocular treatment has now commenced in Guangzhou in collaboration with Professor Mingguang He of the Zhongshan Ophthalmic Centre.