Korean J Ophthalmol.  2015 Jun;29(3):195-202. 10.3341/kjo.2015.29.3.195.

Estimation of Intraocular Lens Power Calculation after Myopic Corneal Refractive Surgery: Using Corneal Height in Anterior Segment Optical Coherence Tomography

• Kim DH
• Kim MK
• Wee WR

• KMID: 2363759
• DOI: http://doi.org/10.3341/kjo.2015.29.3.195

Abstract

PURPOSE
To investigate the feasibility of estimating effective lens position (ELP) and calculating intraocular lens power using corneal height (CH), as measured using anterior segment optical coherence tomography (AS-OCT), in patients who have undergone corneal refractive surgery.
METHODS
This study included 23 patients (30 eyes) who have undergone myopic corneal refractive surgery and subsequent successful cataract surgery. The CH was measured with AS-OCT, and the measured ELP (ELP(m)) was calculated. Intraocular lens power, which could achieve actual emmetropia (P(real)), was determined with medical records. Estimated ELP (ELP(est)) was back-calculated using P(real), axial length, and keratometric value through the SRK/T formula. After searching the best-fit regression formula between ELP(m) and ELP(est), converted ELP and intraocular lens power (ELP(conv), P(conv)) were obtained and then compared to ELP(est) and P(real), respectively. The proportion of eyes within a defined error was investigated.
RESULTS
Mean CH, ELP(est), and ELP(m) were 3.71 +/- 0.23, 7.74 +/- 1.09, 5.78 +/- 0.26 mm, respectively. The ELP(m) and ELP(est) were linearly correlated (ELP(est) = 1.841 x ELP(m) - 2.018, p = 0.023, R = 0.410) and ELP(conv) and P(conv) agreed well with ELP(est) and P(real), respectively. Eyes within +/-0.5, +/-1.0, +/-1.5, and +/-2.0 diopters of the calculated P(conv), were 23.3%, 66.6%, 83.3%, and 100.0%, respectively.
CONCLUSIONS
Intraocular lens power calculation using CH measured with AS-OCT shows comparable accuracy to several conventional methods in eyes following corneal refractive surgery.

Keyword

Anterior segment optical coherence tomography; Corneal height; Corneal refractive surgery; Effective lens position; Intraocular lens power calculation

MeSH Terms

Axial Length, Eye/pathology
Cornea/pathology/*surgery
Humans
*Lenses, Intraocular
Male
Middle Aged
*Refractive Surgical Procedures
Retrospective Studies
Tomography, Optical
Tomography, Optical Coherence

Figure

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  Fig. 1 An anterior segment optical coherence tomography image. The measured corneal height (CHm) was defined as the distance between the posterior corneal surface and the intersection between the perpendicular lines.

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  Fig. 2 Linear regression analysis of measured effective lens position (ELPm) and the estimated effective lens position (ELPest).

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  Fig. 3 Bland-Altman plot showing differences between measured effective lens position (ELPm) and estimated effective lens position (ELPest). Lines showing the mean difference and the ±1.96 standard deviation (SD) limits are also shown.

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  Fig. 4 Bland-Altman plot showing differences between the converted intraocular lens power (Pconv) and the actual intraocular lens power (Preal). Lines showing the mean difference and the ±1.96 standard deviation (SD) limits are also shown.

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