Comparison of Myopia Induced by Retrodots and Nuclear Cataract

Abstract

Purpose: : It is well known that some nuclear cataract cause myopic sift of refraction, but we found that Retrodots would also lead to myopia at some level. In this study, we compared the influence of Retrodots (RD) and nuclear cataract on ocular refraction.

Methods: : 246 cases (444 eyes) who participated in the Monzen Eye Study in 2005 or who received cataract surgery in Kanazawa Medical University Hospital from December 2005 to March 2007were examined retrospectively. Cases with cortical opacity within 3mm diameter of the pupil and posterior subcapsular cataract were excluded. RD was classified into five steps according to the occupancy of the opacity. Nuclear cataract was also graded into four steps by the WHO classification system. Axial length was measured by an A-mode Ultrasound (AL2000,TOMEY). An Auto Kerato-Refractometer (ARK. NIDEK) was used to compute refraction. Lens reflective power was calculated on SPK.

Results: : There was no significant difference in axial length and reflection between the steps. The averages of reflection of RD step 0 to 4 were 0.67D, 0.80D, 0.59D, -0.85D and -0.43D. The average lens refractive power were 17.50D, 17.45D, 16,98D, 19,69D, 18.86D, then we found a remarkable tendency of myopia and increase of lens refractive power (p<0.05). The mean scores of reflection of each nuclear cataract step 0 to 3 were 0.67D, 0.47D, -1.95D, -3.53D, and average lens refractive power were 17.50D, 17.86D, 21,62D and 23,97D. There were also significant myopic tendency and growth of refractive power (p<0.01). The average lens refractive power of complicated cases of over step3 RD and over step2 nuclear cataract were 24.00D, and the average refraction of the cases was -3.59D.

Conclusions: : Nuclear cataract is more influential on refraction than RD. Still Nuclear cataract and RD often result in a complication, and make myopia advance seriously.

Keywords: cataract