IOL Power Calculation After Radial Keratotomy Using the Haigis and Barrett True-K Formulas

Tavares, Renata Leite; Ferreira, Gabriel de Almeida; Ghanem, Vinı́cius Coral; Ghanem, Ramon Coral

doi:10.3928/1081597x-20200930-02

Cited by 13 publications

(12 citation statements)

References 16 publications

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“…The mean absolute value of the predictive refractive error (MAE) was determined by an average of the absolute value of the difference of spherical equivalence between the postoperative manifest refraction and predicted postoperative refraction. The precision of the IOL power calculation is greatest when the MAE approaches zero [9][10][11].…”

Section: Methodsmentioning

confidence: 99%

Double peak axial length measurement signal in cataract patients with epiretinal membrane

et al. 2022

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Purpose: To evaluate the accuracy of axial length (AL) measurement for intraocular lens (IOL) calculation in patients with cataract and epiretinal membrane (ERM).Methods: This prospective, cross-sectional study was performed in cataract patients with ERM. All subjects were sent for standard optical biometry, prepared for cataract surgery. Signals of AL measurement were detected as double peaks and recorded as AL1 ( rst peak), and AL2 (second peak).The IOL power was calculated from AL1 and AL2, and reported as IOL1 and IOL2. The IOL2 was chosen for cataract surgery in all cases. Postoperative predictive errors were compared between IOL1 and IOL2.Results: Thirty-seven eyes from 37 patients were included. Mean AL1 was signi cantly shorter than AL2 (23.13±1.28 vs. 23.60±1.34 mm, p<0.001), resulting in higher power of IOL1 than IOL2 (mean difference was 1.53±0.96 diopters, p<0.001). At 3-months post-operation, twenty-nine eyes (78.4%) (95% CI: 62.8%-88.6%) showed refractive error within ±0.5 diopter and all eyes were within ±1.0 diopter. Postoperative predictive errors including mean arithmetic error (ME) and mean absolute error (MAE) of IOL2 were signi cantly lower than those of IOL1 (ME: IOL1 vs. IOL2, -0.94±0.91 vs. 0.08±0.51; MAE: 0.97±0.88 vs. 0.39±0.33 diopter, all p<0.001).Conclusions: AL measurement in ERM can be detected as a double peak signal during biometric measurement. The IOL power calculated from the rst and second peak signals are signi cantly different. However, the IOL power derived from the second peak signal provides better refractive outcomes. The results suggest that the second peak signal represent an accurate AL measurement.

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Section: Methodsmentioning

confidence: 99%

Double peak axial length measurement signal in cataract patients with epiretinal membrane

et al. 2022

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“…Included among the formulas in the calculator is the Barrett True-K formula, which is built into most biometers and has been shown to offer favorable results for post-RK patients according to multiple recent studies. 2–4…”

Section: Sioux Falls South Dakotamentioning

confidence: 99%

“…The review of literature estimates +/- 0.50 D in 42% to 76.6% of patients. 1–3 Many surgeons will aim for −0.75 to −1.00 for all RK calculations in general to adjust for morning flattening and hyperopic shift over time. The most current approach includes the ASCRS IOL calculator RK with the average 1 mm to 4 mm corneal readings, Pentacam PWR_SF_Pupil_4.0 mm Zone or EKR65, Barrett True-K RK (history and partial history), Double-K Holladay 1 for RK and Haigis (with or without −0.75 D offset).…”

Section: Editors' Commentsmentioning

confidence: 99%

Radial keratotomy and cataract surgery: A quest for emmetropia

Fram¹,

Hovanesian²,

Narang³

et al. 2023

J Cataract Refract Surg

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A 75-year-old man with an ocular history of 8-cut radial keratotomy (RK) in both eyes presented for cataract surgery evaluation. He was previously correctable in spectacles in years prior despite his irregular corneas to 20/25 in the right eye and 20/30 in the left eye. He recently noticed a change in his overall visual function with significant nighttime glare and difficulty reading despite spectacle correction. Of note, he was unable to tolerate contact lenses and was resistant to refitting despite additional encouragement. Cataract surgery was delayed for many years, given he was correctable in spectacles and the concern of uncovering a highly aberrated cornea after removing his cataracts (Figures 1 and 2 JOURNAL/jcrs/04.03/02158034-202308000-00021/figure1/v/2023-07-21T030437Z/r/image-tiff JOURNAL/jcrs/04.03/02158034-202308000-00021/figure2/v/2023-07-21T030437Z/r/image-tiff ). Of note, the patient was interested in returning to the spectacle independence he enjoyed in the past. Ocular examination revealed a corrected distance visual acuity (CDVA) of 20/30 in the right eye and 20/60 in the left eye, with a manifest refraction of +4.50 −0.50 × 177 in the right eye and +5.75 −1.75 × 14 in the left eye. Glare testing was 20/50 in the right eye and 20/100 in the left eye, with retinal acuity meter testing of 20/25 in each eye. Pupils, confrontation visual fields, and intraocular pressures were normal. Pertinent slitlamp examination revealed corneal findings of 8-cut RK with nasal-gaping arcuate incisions in both eyes and lens findings of 2+ nuclear sclerosis with 2+ cortical changes in the right eye and 3+ nuclear sclerosis with 3+ cortical changes in the left eye. Cup-to-disc ratios of the optic nerves measured 0.5 with temporal sloping in the right eye and 0.6 with temporal sloping in the left eye. The dilated fundus examination was unremarkable. What intraocular lens (IOL) options would you offer this patient and how would you counsel regarding realistic expectations? What additional diagnostic testing would be helpful in your assessment? How would you calculate the IOLs?

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“…In a recent retrospective study, the authors compare the performance of the Haigis with the Barrett True K (no history) formulas in post-RK eyes, and all biometries were measured with the IOLMaster 500 or 700 (Carl Zeiss Meditec AG, Jena, Germany). 39 The authors state that the Barrett formula results in a significantly smaller mean arithmetic refractive prediction error (ME) than the Haigis formula (–0.03 ± 0.96 D versus –0.29 ± 1.00 D, p < 0.001). Yet, there was no significant difference in the mean absolute refractive prediction error (MAE), and the Barrett formula tended to lead to hyperopic results in very flat corneas.…”

Section: Iol Power Calculation After Rkmentioning

confidence: 99%

“…Yet, there was no significant difference in the mean absolute refractive prediction error (MAE), and the Barrett formula tended to lead to hyperopic results in very flat corneas. 39 Another retrospective study comparing different subtypes of the Barrett True K formula with other vergence formulas reported the best results with the Barrett True K (history) formula yielding a median absolute error (MedAE) of 0.275 D. 40 Of the formulas not requiring pre-RK refraction, the Haigis formula was found to be most accurate (ME = –0.006 D). It was less accuracy reported for the DK-Holladay-IOLM and Potvin-Hill formulas in this study.…”

Section: Iol Power Calculation After Rkmentioning

confidence: 99%

Intraocular lens power calculation in eyes with previous corneal refractive surgery

Anders

Barbara³

et al. 2022

Ophthalmol Eye Dis

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Intraocular lens (IOL) power calculation after corneal refractive surgery (CRS) becomes an expanding challenge for ophthalmologists as more and more cataract surgeries after CRS are required. These patients typically also have high expectations as to visual performance. Conventional IOL power calculation schemes frequently provide inaccurate results in these cases. This review aims to summarize and recommend currently available IOL power calculation methods for eyes with the most common CRS methods: radial keratotomy (RK), photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), and small incision lenticule extraction (SMILE). To this end, biometry measuring methods and IOL formulas will be explained and combinations of both are proposed. In synopsis, it is evident that the latest generation of vergence formulas exhibit favorable IOL power prediction accuracy in post-CRS eyes, even though the predictive precision of methods in eyes without CRS is not attained. Ray tracing computation, intraoperative aberrometry, and machine learning–based formulas hold potential to further improve refractive outcomes in post-CRS eyes.

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IOL Power Calculation After Radial Keratotomy Using the Haigis and Barrett True-K Formulas

Cited by 13 publications

References 16 publications

Double peak axial length measurement signal in cataract patients with epiretinal membrane

Double peak axial length measurement signal in cataract patients with epiretinal membrane

Radial keratotomy and cataract surgery: A quest for emmetropia

Intraocular lens power calculation in eyes with previous corneal refractive surgery

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