Intraocular lens power calculations for cataract surgery after phototherapeutic keratectomy in granular corneal dystrophy type 2.
OBJECTIVE
To investigate the predictability of various intraocular lens (IOL) power calculation methods in granular corneal dystrophy type 2 (GCD2) with prior phototherapeutic keratectomy (PTK) and to suggest the more predictable IOL power calculation method.


METHODS
Medical records of 20 eyes from 16 patients with GCD2, all having undergone cataract surgery after PTK, were retrospectively evaluated. Postoperative cataract refractive errors were compared with target diopters (D) using IOL power calculation methods as follows: 1) myopic and 2) hyperopic Haigis-L formula in IOLMaster (Carl Zeiss Meditec); 3) SRK/T formula using 4.5-mm zone Holladay equivalent keratometry readings (EKRs) (single-K Holladay EKRs method); 4) central keratometry power of true net power map in the Pentacam system (Oculus Optikgeräte GmbH); and 5) clinical history, Aramberri double-K, and double-K Holladay EKRs methods. Topographic status of corneal curvature after PTK was evaluated.


RESULTS
Fourteen (70%) of 20 eyes showed central island formation after PTK. When central island was present, the mean absolute error (MAE) using the hyperopic Haigis-L formula was 0.25±0.15 D. When central island was not present, the myopic Haigis-L formula showed MAE of 0.33±0.16 D. When central island formation and IOLMaster keratometry underestimation were present, the hyperopic Haigis-L formula showed the least MAE of 0.26±0.08 D when switching the IOL-Master keratometry values equal to 4.5-mm zone Holladay EKRs.


CONCLUSIONS
In planning for cataract surgery after PTK in GCD2, topographic analysis for central island formation is necessary. With or without central island formation, the hyperopic or myopic Haigis-L formula can be applied. When IOLMaster keratometry shows underestimation, the Haigis-L formula using 4.5-mm zone Holladay EKRs can be considered.
Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
Se Hwan
SH
Jung
Kyung Eun
KE
Han
Bradford
B
Sgrignoli
Tae-Im
TI
Kim
Hyung Keun
HK
Lee
Eung Kweon
EK
Kim
D000368:Aged; D000867:Anterior Chamber / Q000473:pathology; D058452:Axial Length, Eye / Q000473:pathology; D002387:Cataract Extraction; D003317:Corneal Dystrophies, Hereditary / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D018903:Photorefractive Keratectomy; D011182:Postoperative Care; D012189:Retrospective Studies