Nuclear cataract and myopic shift in refraction.
OBJECTIVE
Nuclear cataract is thought to cause a myopic shift in refraction in older persons. The authors tested this hypothesis by assessing the correlation of nuclear opacity with spherical equivalent refraction (SER) in an older population.


METHODS
Population-based cross-sectional study.


METHODS
Three thousand six hundred and fifty-four participants aged 49 years or older were examined in the Blue Mountains Eye Study [BMES] (1992 to 1994). Eye examinations included subjective refraction and lens photographs. Nuclear opacity was assessed against four standard slit-lamp lens photographs using the Wisconsin Cataract Grading System. Nuclear cataract was defined as opacity level 4 or higher.


RESULTS
Participants without nuclear cataract had an annual mean hyperopic shift of 0.05 diopters (P < .0001). In persons with nuclear cataract, this hyperopic shift disappeared. A myopic refractive shift occurred only in persons with nuclear opacity levels of 4 or higher.


CONCLUSIONS
This study documents the contribution of nuclear cataract to the mild myopic shift that neutralizes the age-related hyperopic shift occurring in older persons.
Samarawickrama
Chameen
C
Centre for Vision Research, Department of Ophthalmology, Westmead Millennium Institute, University of Sydney, Sydney, Australia.
Wang
Jie Jin
JJ
Burlutsky
George
G
Tan
Ava G
AG
Mitchell
Paul
P
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D002386:Cataract / Q000150:complications*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology; D007907:Lens Nucleus, Crystalline / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000209:etiology* / Q000503:physiopathology; D009517:New South Wales; D012029:Refraction, Ocular / Q000502:physiology