Posterior Corneal Characteristics of Cataract Patients with High Myopia.
OBJECTIVE
To evaluate the characteristics of the posterior corneal surface in patients with high myopia before cataract surgery.


METHODS
We performed a cross-sectional study at the Eye and ENT Hospital of Fudan University, Shanghai, China. Corneal astigmatism and axial length were measured with a rotating Scheimpflug camera (Pentacam) and partial coherence interferometry (IOLMaster) in a high-myopia study group of 167 eyes (axial length ≥ 26 mm) and a control group of 150 eyes (axial length > 20 mm and < 25 mm).


RESULTS
Total corneal astigmatism and anterior corneal astigmatism values were higher in the high-myopia group than in the control group. There was no significant difference in posterior corneal astigmatism between the high-myopia study group and the control group. In the study group, the mean posterior corneal astigmatism (range 0 - -0.9 diopters) was -0.29 diopters (D) ± 0.17 standard deviations (SD). The steep corneal meridian was aligned vertically (60°-120°) in 87.43% of eyes for the posterior corneal surface, and did not change with increasing age. There was a significant correlation (r = 0.235, p = 0.002) between posterior corneal astigmatism and anterior corneal astigmatism, especially when the anterior corneal surface showed with-the-rule (WTR) astigmatism (r = 0.452, p = 0.000). There was a weak negative correlation between posterior corneal astigmatism and age (r = -0.15, p = 0.053) in the high-myopia group. Compared with total corneal astigmatism values, the anterior corneal measurements alone overestimated WTR astigmatism by a mean of 0.27 ± 0.18 D in 68.75% of eyes, underestimated against-the-rule (ATR) astigmatism by a mean of 0.41 ± 0.28 D in 88.89% of eyes, and underestimated oblique astigmatism by a mean of 0.24 ± 0.13 D in 63.64% of eyes.


CONCLUSIONS
Posterior corneal astigmatism decreased with age and remained as ATR astigmatism in most cases of high myopia. There was a significant correlation between posterior corneal astigmatism and anterior corneal astigmatism when anterior corneal astigmatism was WTR. If posterior corneal astigmatism is not accounted for when selecting toric intraocular lenses for high-myopia patients, the use of anterior corneal astigmatism measurements alone will lead to overestimation of WTR astigmatism and underestimation of ATR and oblique astigmatism.
Department of Ophthalmology and Vision Science, Eye and ENT Hospital of Fudan University, Shanghai, China.|Key Laboratory of Myopia of State Health Ministry, and Key Laboratory of Visual Impairment and Restoration of Shanghai, Shanghai, China.
Qinghe
Q
Jing
Department of Ophthalmology and Vision Science, Eye and ENT Hospital of Fudan University, Shanghai, China.|Key Laboratory of Myopia of State Health Ministry, and Key Laboratory of Visual Impairment and Restoration of Shanghai, Shanghai, China.
Yating
Y
Tang
Department of Ophthalmology and Vision Science, Eye and ENT Hospital of Fudan University, Shanghai, China.|Key Laboratory of Myopia of State Health Ministry, and Key Laboratory of Visual Impairment and Restoration of Shanghai, Shanghai, China.
Dongjin
D
Qian
Department of Ophthalmology and Vision Science, Eye and ENT Hospital of Fudan University, Shanghai, China.|Key Laboratory of Myopia of State Health Ministry, and Key Laboratory of Visual Impairment and Restoration of Shanghai, Shanghai, China.
Yi
Y
Lu
Department of Ophthalmology and Vision Science, Eye and ENT Hospital of Fudan University, Shanghai, China.|Key Laboratory of Myopia of State Health Ministry, and Key Laboratory of Visual Impairment and Restoration of Shanghai, Shanghai, China.
Yongxiang
Y
Jiang
D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000503:physiopathology* / Q000601:surgery; D058452:Axial Length, Eye / Q000503:physiopathology; D002386:Cataract / Q000503:physiopathology*; D002387:Cataract Extraction; D002681:China; D003315:Cornea / Q000503:physiopathology*; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular / Q000379:methods; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology* / Q000601:surgery