1. Biometric Accuracy in High Hypermetropes and Myopes
Mangat S, Kumar B V, Prasad S
Arrowe Park Hospital,
Wirral University Hospital NHS Trust
No financial interests

2. Introduction
Cataract surgery in patients with myopia and hypermetropia can be technically challenging .
These challenges arise due to extremes of axial length which can lead to complications during biometry.
This can lead to potential intra and postoperative complications particularly with postoperative surprises particularly anisometropia.
Hence obtaining accurate biometry in these patients is essential to ensure that the cataract surgery is successful.

3. Methods
Retrospective review of medisoft database was undertaken of cataract surgery carried out between Jan September 2009
Surgery was carried out by Consultants, Fellow and Registrars.
Myopia is defined when patient has an axial length more than 26mm
Hypermetropia is defined when patient has an axial length less than 22mm
Preoperative refraction, biometry measurements , visual acuity pre and post cataract surgery were all documented.
Deviation from
- predicted postoperative outcome and
- final best corrected visual acuity were recorded

4. Results Axial length < 22mm Axial length >26mm
Number of Patients
632
245
Number of Operations
764
297
Data Available
585
225
Mean Age of Patient
76.3
68.5
Age Range
37-95
13-93
Mean Post Op Spherical Equivalent
-0.01+/-1.20 (SD) (95%CI +/- 0.11)
/-0.95(SD) (95% CI +/-0.12)
Mean Deviation From Predicted Refraction
-0.01+/ (SD) (95% CI +/- 0.08)
-0.09+/ (SD) (95% CI +/- 0.17)
Predicted Post Operative Refraction +/- 1 D of predicted
484
192
<-1D of predicted 54 20
>1D of predicted 45 12

8. Main IOL Models Inserted
(%)
Axial Length <22mm
Axial Length 22-26mm
Axial Length >26mm
B&L L161AO
50.95
47.88
48.55
B&L L161SE
30.13
27.99
26.97
Chiron soflex 2
14.67
21.2
19.5
B&L M160
1.74
1.83
1.24

9. Conclusions
Postoperative refraction in the <22mm and >26mm groups was within +/-1D in 84% and 86 % respectively
There was no statistically significant difference between the mean post operative spherical equivalent (<22mm) and 0.70 (>26mm). Paired Student t Test >0.05
There was no statistically significant difference between the mean deviation from predicted refraction (<22mm) and (>26mm). Paired student t Test >0.05

10. Conclusions
89.5% cases with Axial Lengths 22-26mm had a postoperative refraction of +/- 1D
Some postoperative surprises were noted as a result of Biometry errors which was rectified later with further surgery.
It may be wise to discuss this finding preoperatively when dealing with patients with extremes of axial length

11. Available Evidence
Zuberbuhler et al state that 53.2% of patients were +/- 1D of predicted in those with axial lengths above 30mm
Lyle et al studied 106 highly myopic eyes. Postoperative corrected visual acuity was 20/40 or better in 94% of eyes, and uncorrected visual acuity was 20/40 or better in 77% of eyes at 27 months in those with axial lengths >26mm
Maclaren et al state 55% patients were +/- 1D of predcited in 76 eyes requiring IOLs between 30-35D

12. References
1. Zuberbuhler B, Seyedian M, Tuft S. Phacoemulsification in eyes with extreme axial myopia. J Cataract Refract Surg Feb;35(2):
2. Lyle et al. Phacoemulsification with intraocular lens implantation in high myopia. J Cataract Refract Surg Mar;22(2):
3. MacLaren RE et al. Biometry and formula accuracy with intraocular lenses used for cataract surgery in extreme hyperopia. Am J Ophthalmol Jun;143(6):