3. Shingleton BJ, Nguyen BKC, Eagan EF, Nagao K,

O’Donoghue MW. Outcomes of phacoemulsification in fellow

eyes of patients with unilateral pseudoexfoliation: single- surgeon

series. J Cataract Refract Surg 2008; 34:274–279

4. Poley BJ, Lindstrom RL, Samuelson TW. Long-term effects of

phacoemulsification with intraocular lens implantation in normo-

tensive and ocular hypertensive eyes. J Cataract Refract Surg

2008; 34:735–742

5. Shingleton BJ, Gamell LS, O’Donoghue MW, Baylus SL, King R.

Long-term changes in intraocular pressure after clear corneal pha-

coemulsification: normal patients versus glaucoma suspect and

glaucoma patients. J Cataract Refract Surg 1999; 25:885–890

6. Merkur A, Damji KF, Mintsioulis G, Hodge WG. Intraocular pres-

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27:528–532

954 CORRESPONDENCE

Partial coherence interferometryin a teaching hospital

Leslie A. Wei, Nickolas Katsoulakis, MD,Theodoros Filippopoulos, MD, Paul B. Greenberg, MD

Partial coherence interferometry (PCI) has an 8% to22% failure rate for a variety of reasons such as maturecataract, inability to fixate secondary to macular de-generation, tremor, keratopathy, nystagmus, and vit-reous hemorrhage.1–4 The new composite IOLMasterversion 5 software has demonstrated a failure rate of7.4%, primarily because of posterior subcapsular cata-racts.5 Few studies of the efficacy of PCI in a teachinghospital setting have been done. We investigated thePCI failure rate with the IOLMaster (Carl Zeiss Medi-tec) in a resident ophthalmology clinic at a VeteransAffairs hospital.

After investigative review board approval was ob-tained, the biometric measurements of 147 consecutivepatients (165 eyes) who had resident-performed cata-ract surgery from September 2007 to June 2008were ex-amined. Thirty-nine patients (42 eyes) were excludedbecause of incomplete electronic medical records(EMRs). One hundred eight patients (123 eyes) metthe inclusion criteria; 106 were men (98.1%). Themean age of the patients was 72.4 years (range 50 to91 years). Forty-six eyes (37.4%) were documented

J CATARACT REFRACT SUR

PCI failures that required immersion A-scan for axiallength determination. The subgroup of 88 eyes thathad IOLMaster version 4 readings had a failure rateof 43.2%, whereas the subgroup of 35 eyes with IOL-Master version 5 readings had a significantly lower fail-ure rate of 22.9% (odds ratio Z 0.38, P!.05). All PCIfailures were due to dense cataract. The mean preoper-ative best corrected visual acuity (BCVA) was 20/60 inthosewhohad successful PCI comparedwith!20/400in those requiring immersion A-scan (P Z.01).

The limitations of this study include the retrospec-tive nature, variability in measurements secondary todifferent resident physicians performing PCI, smallsample size, a large number of exclusions due toincomplete EMRs, and inability to analyze the PCIfailures by type of cataract because of variable gradingof cataracts.

The study suggests that the PCI biometry failurerate is still significant in the veteran population dueto dense cataracts, although the version 5 software ap-pears to decrease this rate. The study also suggests thatpoor preoperative vision is a predictor of PCI failure.We look forward to continued improvements in PCIthat will facilitate preoperative biometry in cases ofadvanced cataract in teaching hospital settings.

REFERENCES1. Narvaez J, Cherwek DH, Stulting RD, Waldron R,

Zimmerman GJ, Wessels IE, Waring GO III. Comparing immer-

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ular lens power calculation. Ophthalmic Surg Lasers Imaging

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2. Haigis W, Lege B, Miller N, Schneider B. Comparison of immer-

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for intraocular lens calculation according to Haigis. Graefes

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3. Rajan MS, Keilhorn I, Bell JA. Partial coherence laser interferom-

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calculations. Eye 2002; 16:552–556

4. Ueda T, Taketani F, Ota T, Hara Y. Impact of nuclear cataract

density on postoperative refractive outcome: IOL Master versus

ultrasound. Ophthalmologica 2007; 221:384–387

5. Hill W, Angeles R, Otani T. Evaluation of a new IOLMaster algo-

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