Comparison of the Accuracy of Newer Intraocular Lens Power Calculation Methods in Eyes That Underwent Previous Phototherapeutic Keratectomy.

PURPOSE: To evaluate the accuracy of intraocular lens (IOL) power calculations using ray tracing software in patients who had undergone phototherapeutic keratectomy (PTK). METHODS: In this retrospective case series, 37 eyes of 22 patients (mean age: 69.4 years; range: 56 to 85 years) who underwent cataract surgery after PTK were reviewed. The prediction error, defined as the difference between the estimated postoperative spherical equivalent and the postoperative manifest refraction at the spectacle plane, was calculated using the following formulas: OKULIX (Tedics, Dortmund, Germany), PhacoOptics (IOL Innovations ApS, Aarhus, Denmark), Barrett True K No History (NH), and Camellin-Calossi. The PhacoOptics formula was used in three different ways: historical method (H), no history method (NH), and C-constant method (C). The median values of the arithmetic and absolute prediction errors among these six IOL calculation methods were compared. RESULTS: The median arithmetic errors (in diopters [D]) and percentages of eyes within ±0.50 D of the absolute errors were as follows: OKULIX (0.33, range: -2.20 to 2.50, 30.6%), PhacoOptics (H) (-0.12, range: -3.28 to 4.85, 22.2%), PhacoOptics (NH) (-0.25, range: -2.08 to 1.70, 48.4%), PhacoOptics (C) (0.04, range: -1.40 to 2.18, 48.5%), Barrett True K (NH) (-0.35, range: -1.90 to 1.89, 48.6%), and Camellin-Calossi (-0.19, range: -1.78 to 1.47, 59.5%). CONCLUSIONS: The PhacoOptics, especially the C-constant method (C), and Camellin-Calossi formulas were good options for calculating IOL powers in eyes that underwent PTK. [J Refract Surg. 2019;35(5):310-316.].

Comparison of the accuracy of intraocular lens power calculations for cataract surgery in eyes after phototherapeutic keratectomy.

PURPOSE: To compare the accuracy of several methods of intraocular lens (IOL) power calculations used for cataract surgery in eyes treated with phototherapeutic keratectomy (PTK) that results in changes in the anterior corneal surface and axial length; these results make power calculations less predictable. METHODS: We evaluated the medical records of 23 eyes of 13 patients (mean age, 68.8 years; range 62-80 years) who underwent cataract surgery after PTK at Keio University Hospital, Tokyo, Japan. The prediction error, defined as the difference between the estimated postoperative spherical equivalent and the postoperative manifest refraction at the spectacle plane, was calculated using five formulas: SRK/T, Haigis-L, Shammas-PL, Camellin-Calossi, and OKULIX ray tracing software. We compared the median values of the arithmetic and absolute prediction errors among the five formulas. RESULTS: The median arithmetic errors after cataract surgery for the five formulas were 0.70 D (diopter) (range -0.41 to 2.78), -0.96 D (range -2.14 to 0.81), -0.81 D (range -1.89 to 1.15), -0.04 D (range -1.35 to 1.47), and 0.68 D (range -0.61 to 2.50), respectively. CONCLUSION: The Camellin-Calossi formula is a good option for calculating IOL powers in eyes that underwent PTK.

Effect of neodymium:YAG laser capsulotomy on visual function in patients with posterior capsule opacification and good visual acuity.

PURPOSE: To evaluate the effect of neodymium:YAG (Nd:YAG) laser capsulotomy on the visual function in patients with posterior capsule opacification (PCO) and good visual acuity. SETTING: Keio University Hospital, Tokyo, Japan. DESIGN: Observational case series. METHODS: Eyes were evaluated that had previous cataract surgery with a clinical diagnosis of PCO requiring Nd:YAG laser capsulotomy regardless of a good corrected distance visual acuity (CDVA) (at least 20/20). The CDVA, 10% low contrast visual acuity (LCVA), wavefront aberrations from the 3rd to 6th order, and retinal straylight were measured before and after Nd:YAG laser capsulotomy. RESULTS: The study included 16 eyes of 16 patients (10 men, 6 women; mean age 69.5 years ± 9.3 [SD]). The mean CDVA, LCVA, and straylight after Nd:YAG laser capsulotomy improved significantly (P < .05). The root mean square (RMS) of the 3rd Zernike coefficients (S3) and the RMS of the total higher-order aberrations (HOAs) from the 3rd to 6th order decreased significantly after capsulotomy (P < .05). The straylight correlated significantly with the total HOAs (r = 0.727, P = .002) and S3 (r = 0.748, P = .001) before capsulotomy. Subjective symptoms resolved after capsulotomy in all cases. CONCLUSIONS: Neodymium:YAG laser capsulotomy enabled a significant improvement in visual function even in patients with PCO with good visual acuity. Straylight measurements might be useful to determine the indications for Nd:YAG laser capsulotomy when patients report visual disturbances without decreased visual acuity.

Changes in corneal aberrations after cataract surgery.

PURPOSE: To study the changes in corneal aberrations after cataract surgery. METHODS: This study comprised 36 eyes of 36 patients (mean age, 67.3 years) who underwent cataract surgery through a 2.2-mm superior sclerocorneal incision. The anterior, posterior, and total corneal wavefront aberrations for the 6.0-mm pupillary diameter were measured preoperatively and 1 month postoperatively. The postoperative changes in corneal aberrations were evaluated for individual Zernike terms (Z 2 (-2) , Z 2 (0) , Z 2 (2) , Z 3 (-1) , Z 3 (1) , and Z 4 (0) ) and the root mean squares of the third, fourth, and total higher-order aberrations (S3, S4, and THOA). RESULTS: No significant postoperative changes were observed in S3 and S4 of the total and anterior cornea, although significant changes were observed in S4 and THOA of the posterior cornea. Regarding the preoperative and postoperative Zernike terms of the total cornea, the oblique astigmatism (Z 2 (-2) ) changed significantly (P = 0.02). Significant positive correlations were observed in the Z 2 (-2) , Z 2 (0) , Z 2 (2) Z 3 (-1) , Z 3 (1) and Z 4 (0) between the changes in the total and the anterior cornea (P < 0.001 for all comparisons). However, no correlations were observed in the changes in the Zernike terms between the total and the posterior cornea, except for the Z 2 (0) . CONCLUSIONS: The oblique astigmatism (Z 2 (-2) ) of the total cornea significantly changed after 2.2-mm-incision cataract surgery. The changes in the lower- and higher-order aberrations of the anterior cornea mainly contributed to the changes in the total cornea.

Functional Visual Acuity of Early Presbyopia.

PURPOSE: To evaluate visual function in patients with early presbyopia using the functional visual acuity (FVA) test. METHODS: This study included 27 eyes of 27 healthy older volunteers (mean age, 44.1 ± 2.6 years) and 14 eyes of 14 healthy young volunteers (mean age, 28.4±4.8 years). The distance-corrected visual acuity (DCVA), distance-corrected near VA (DCNVA), subjective amplitude of accommodation (AA), and distance and near pupillary diameters were measured. The distance FVA and distance-corrected near FVA (DCNFVA) were measured using the FVA Measurement System. The standard Schirmer test and standard tear break-up time measurement also were performed. RESULTS: The logarithm of the minimum angle of resolution (logMAR) DCVA was better than 0 in all subjects. The percentages of subjects with logMAR DCNVA below 0 was significantly lower in the presbyopia group than in the young group. The DCNFVA in the presbyopia group was significantly (P < 0.001) poorer than the DCNVA in that group. Significant linear negative correlations were seen between the DCNVA and AA (r = -0.507, P < 0.001) and the DCNFVA and AA (r = -0.681, P < 0.001) in the older subjects. Stepwise regression analysis showed that only the AA was a significant factor predictive of the DCNFVA in the presbyopia group. Tear function parameters were not adopted in the regression model. CONCLUSIONS: Measurement of the DCNFVA can detect decreased AA in early presbyopia better than measurement of the conventional near VA. The DCNFVA is a good index for early presbyopia.

Apparent progression of presbyopia after laser in situ keratomileusis in patients with early presbyopia.

PURPOSE: To assess the effect of laser in situ keratomileusis (LASIK) on near visual function in presbyopic patients. DESIGN: Retrospective cohort study. METHODS: Fifty-three eyes of 40 patients 45 years of age and older who had undergone LASIK for high myopia (-6 diopters [D] and over) were included. The minimal add powers for obtaining the best-corrected near visual acuity (add powers) were measured preoperatively and 3 months postoperatively, and the correlations with the powers corrected by LASIK, corneal higher-order aberrations (HOAs), ocular HOAs, and patient ages were evaluated using univariate analysis. Factors correlated with the changes in add powers were evaluated further by multivariate analysis. RESULTS: The mean ± standard deviation patient age was 50.0 ± 4.1 years; the power corrected by LASIK was -7.56 ± 1.06 D. The mean add power was 1.80 ± 0.60 D preoperatively, which increased significantly (P < .001) to 2.18 ± 0.69 D postoperatively. Significant correlations with the increased add powers were detected with age (P = .01) and the power corrected by LASIK (P = .04) but not with corneal and ocular HOAs (P > .05). Multivariate analysis showed that only age was correlated significantly (P = .01). The percentage of eyes with increased add powers of 0.5 D or more was 60.4%, which was significantly (P = .02) higher in younger patients. CONCLUSIONS: This study verified the apparent progression of presbyopia after LASIK and the importance of obtaining informed consent from patients, especially those with early presbyopia.

Ray tracing software for intraocular lens power calculation after corneal excimer laser surgery.

PURPOSE: To evaluate the accuracy of intraocular lens (IOL) power calculations using ray tracing software in eyes after myopic laser in situ keratomileusis (LASIK). METHODS: Twenty-four eyes of 17 cataract patients who underwent phacoemulsification and IOL implantation after myopic LASIK were analyzed retrospectively. The IOL power calculation was performed using OKULIX ray tracing software. The axial length was measured using the IOLMaster and keratometry data using TMS2N. The accuracy of the IOL power calculation using OKULIX was compared with those using the Camellin-Calossi, Shammas-PL, Haigis-L formulas and the double-K SRK/T formula using 43.5 diopters (D) for the Kpre. RESULTS: The mean values of the arithmetic and absolute prediction errors were 0.63 ± 0.85 and 0.80 ± 0.68 D, respectively. The arithmetic prediction error by OKULIX was a significant hyperopic shift of the distribution of the postoperative refractive errors compared to the Camellin-Calossi, Shammas-PL and Haigis-L formulas (P < 0.05), and the absolute prediction error showed no significant difference with other formulas. The prediction errors using OKULIX were within ± 0.5 D in 10 eyes (41.7 %) and within ± 1.0 D in 18 eyes (75.0 %). The percentages of eyes within ± 1.0 D using OKULIX were comparable to those obtained using the Camellin-Calossi, the Shammas-PL formulas and the double-K SRK/T formula using 43.5 D for the Kpre, and significantly (P < 0.05) higher than that obtained using the Haigis-L formula. CONCLUSIONS: IOL power calculations using OKULIX provided predictable outcomes in eyes that had undergone a previous myopic LASIK.

Changes in higher-order aberrations after iris-fixated phakic intraocular lens implantation.

PURPOSE: To evaluate surgically induced changes in corneal, internal, and ocular higher-order aberrations (HOAs) after phakic intraocular lens (PIOL) implantation and compare them between two PIOLs with different pupillary diameters. METHODS: Twenty-three eyes with an Artisan PIOL (Ophtec BV, Groningen, The Netherlands) (Artisan group) and 30 eyes with an Artiflex PIOL (Ophtec BV) (Artiflex group) were retrospectively evaluated. The corneal, internal, and ocular HOAs and refractive data were recorded preoperatively and 6 months postoperatively. The root mean squares (RMSs) of the total HOAs from the third- to sixth-order Zernike coefficients were calculated. The RMSs of the third- and fourth-order coefficients represented coma-like aberrations (S3) and spherical-like aberrations (S4), respectively. The main outcome measures were the differences in the parameters among the groups with different pupillary diameters. RESULTS: The mean postoperative spherical equivalents decreased from -11.84 ± 4.90 to -0.16 ± 0.40 diopters and -9.78 ± 3.20 to -0.09 ± 0.26 diopters in the Artisan and Artiflex groups, respectively. With the 4- and 5-mm pupillary diameters, the postoperative internal and ocular spherical aberrations (Z4(0)) were significantly lower in the Artiflex group than in the Artisan group (4 mm, P = .002, .024; 5 mm, P = .004, .022, respectively). With the 6-mm pupillary diameter, there were no significant postoperative differences in any parameter measured between groups; both groups had positive spherical aberration values. CONCLUSIONS: The postoperative ocular spherical aberrations were positive after Artisan and Artiflex implantation. The postoperative ocular spherical aberration was greater in the Artisan group, possibly due to differences in the SAs of both PIOLs.

Deep stromal opacity after corneal cross-linking.

PURPOSE: To describe 3 cases with deep corneal stromal opacity that occurred several months after corneal cross-linking. METHODS: A 36-year-old man, a 19-year-old man, and a 14-year-old girl underwent corneal cross-linking for their progressive keratoconus. Corneal cross-linking was performed according to the Dresden protocol. The corneal epithelium was ablated using an excimer laser in 2 cases and manually in 1 case. After 30 minutes of riboflavin presoaking, hypotonic riboflavin solution was applied until the corneal stroma swelled, after which the eyes were exposed to ultraviolet irradiation. Slit-lamp microscopy findings, uncorrected visual acuity, best-corrected visual acuity, manifest refraction, intraocular pressure, and corneal endothelial cell counts were evaluated, and corneal topography with Scheimpflug imaging was performed. RESULTS: In all cases, the epithelium healed without delay. All eyes showed mild stromal infiltration a few days after the procedure; however, the inflammation was resolved within 1 week. The corneal stroma revealed no opacity up to 1 month after the procedure. A deep stromal opacity that extended to the inferior paracentral area developed after a few months and remained for 6 months to 1 year. Because the opacity was not on the visual axis, the visual acuity was not involved. CONCLUSIONS: Deep stromal opacity developed several months after uneventful corneal cross-linking. Postoperative inflammation may play a crucial role in its pathogenesis.

Modified double-K method for intraocular lens power calculation after excimer laser corneal refractive surgery.

PURPOSE: To propose the new anterior-posterior method (A-P method) that does not require historical data to calculate intraocular lens (IOL) power after laser in situ keratomileusis (LASIK) and to compare the accuracy of the method with other IOL formulas after LASIK. SETTING: Keio University Hospital, Tokyo, Japan. DESIGN: Case series. METHODS: Eyes having phacoemulsification and IOL implantation after myopic LASIK were analyzed retrospectively. The A-P method is a modification of the double-K method using the SRK/T formula in which the estimated pre-LASIK keratometry (K) power calculated from the post-LASIK posterior sagittal power in the 6.0 mm zone is used for the preoperative K value in the double-K method and the post-LASIK anterior sagittal power is used for the postoperative K value. The accuracy of the A-P method was compared with that of other formulas that do not require preoperative data and with formulas that require preoperative data. RESULTS: The median values of the arithmetic and absolute prediction errors using the A-P method were 0.16 diopter (D) and 0.54 D, respectively. The prediction errors using the A-P method were within ± 0.50 D in 46.4% of eyes and within ± 1.00 D in 75.0%. The percentage of eyes within ± 1.00 D of the prediction errors with the A-P method was highest with the no-history methods. CONCLUSION: The A-P method may be a good option for calculating IOL power in eyes having cataract surgery after LASIK when preoperative LASIK data are unavailable.

A new central-peripheral corneal curvature method for intraocular lens power calculation after excimer laser refractive surgery.

PURPOSE: To propose the central-peripheral (C-P) method, which requires no data history to calculate intraocular lens (IOL) powers for eyes that underwent laser in situ keratomileusis (LASIK), and compare the accuracy of the C-P method with other IOL formulas for eyes after LASIK. METHODS: Sixteen patients with cataract (25 eyes) who underwent myopic LASIK were analysed retrospectively. The C-P method is a modified double-K method using the SRK/T formula, in which the estimated pre-LASIK keratometric power calculated from the post-LASIK peripheral anterior sagittal power (also called the axial power) is used for the Kpre in the double-K method using the SRK/T formula, and the post-LASIK anterior sagittal power is used for the Kpost. We compared the accuracy of the C-P method with other popular IOL calculation formulas for use in eyes after LASIK. RESULTS: The median values of the arithmetic and absolute prediction errors with the C-P method were 0.11 diopter (D) (range, -1.67 to 1.97 D) and 0.55 D (range, 0.02-1.97 D), respectively. The prediction error using the C-P method was within ±0.5 D in 48% of eyes, within -1.0 to +0.5 D in 60% of eyes, and within ±1.0 D in 68% of eyes. The C-P method resulted in a significantly higher percentage of eyes within ±0.5 D than the BESSt formula, Shammas-PL formula, true net power method, double-K method using 43.5 D for Kpre, and Feiz-Mannis method. CONCLUSION: The C-P method may be a good option for calculating IOL powers in eyes undergoing cataract surgery after LASIK when the preoperative LASIK data are unavailable.

Simple and accurate alignment of toric intraocular lenses and evaluation of their rotation errors using anterior segment optical coherence tomography.

PURPOSE: To describe a new method of alignment of toric intraocular lenses (IOLs) and evaluation of their rotation errors using anterior segment optical coherence tomography (AS-OCT). METHODS: Twenty-nine eyes of 22 patients who had cataract extraction and implantation of an acrylic toric IOL were included. The new AS-OCT method was used for the alignment of toric IOLs and evaluation of their rotation errors. These rotation errors were evaluated and compared with those measured using the internal map of a wavefront aberrometer. RESULTS: The mean rotation error ± standard deviation (SD) of the toric IOLs evaluated by AS-OCT was 3.2 ± 2.2° and 3.2 ± 2.4° at 1 week and 1 month after surgery, respectively. The mean difference in the reference axis between the visits was 1.8 ± 2.1°. The mean difference between the rotation errors of the alignment axes measured by AS-OCT and the internal map was 2.5 ± 1.9° (P = 0.037). CONCLUSION: The current method is clinically useful not only for the accurate alignment of toric IOLs but also for evaluating their rotation errors.

Functional visual acuity after neodymium:YAG laser capsulotomy in patients with posterior capsule opacification and good visual acuity preoperatively.

PURPOSE: To evaluate the changes in functional visual acuity before and after neodymium:YAG (Nd:YAG) laser capsulotomy. SETTING: Keio University Hospital, Tokyo, Japan. DESIGN: Case series. METHODS: Eyes that had previous cataract surgery with a clinical diagnosis of central posterior capsule opacity requiring Nd:YAG laser capsulotomy were evaluated. All patients had refractive error and corrected distance visual acuity (CDVA) measurements; slitlamp microscopy examinations, including posterior capsule opacification evaluation; high-contrast visual acuity measured at 5 m using a Landolt chart; 10% low-contrast visual acuity (LCVA); functional visual acuity; wavefront examination; and a Schirmer test without anesthesia. RESULTS: The study enrolled 9 patients (4 women, 5 men; 10 eyes) with a mean age of 57.3 years ± 7.0 (SD) (range 47 to 68 years). Although there was no significant difference in CDVA before and after Nd:YAG capsulotomy, there was a significant improvement in the mean functional visual acuity, from 0.18 ± 0.11 logMAR (range -0.03 to 0.31 logMAR) to 0.08 ± 0.07 logMAR (range -0.04 to 0.18 logMAR) (P < .05). The LCVA improved significantly after Nd:YAG laser capsulotomy (P = .003). Higher-order aberrations and the root mean square of the 4th-order coefficients decreased significantly after capsulotomy, and these aberrations were significantly correlated with functional visual acuity and LCVA. CONCLUSION: Results indicate that measurement of functional visual acuity is useful in assessing the quality of vision in patients who have Nd:YAG laser capsulotomy after cataract surgery.

Predictability of ocular spherical aberration after cataract surgery determined using preoperative corneal spherical aberration.

PURPOSE: To evaluate the predictability of total postoperative spherical aberration after aspheric intraocular lens (IOL) implantation using preoperative corneal spherical aberration. SETTING: Keio University Hospital, Tokyo, Japan. METHODS: Corneal and ocular higher-order aberrations (HOAs) were analyzed preoperatively and postoperatively in eyes having cataract extraction with aspheric IOL implantation. The predicted postoperative total spherical aberration Z(4,0) was calculated by adding the preoperative corneal spherical aberration and the labeled spherical aberration of the IOL. The prediction error of the postoperative total spherical aberration was calculated by subtracting the predicted postoperative total spherical aberration from the postoperative total spherical aberration. Surgically induced corneal spherical aberration was calculated by subtracting the postoperative from the preoperative corneal spherical aberration. RESULTS: There were no statistically significant differences between preoperative and postoperative corneal spherical aberration, 3rd-order aberration, or HOAs. The prediction error of the postoperative total spherical aberration was within +/-0.05 microm in 9 (24.3%) of the 37 eyes evaluated and within +/-0.10 microm in 18 eyes (48.6%). Statistically significantly correlations were found between the surgically induced corneal spherical aberration and prediction error of postoperative total spherical aberration, the preoperative corneal spherical aberration and surgically induced corneal spherical aberration, and the preoperative corneal spherical aberration and prediction error of postoperative total spherical aberration. CONCLUSIONS: Predictability of postoperative ocular spherical aberration after cataract surgery with aspheric IOL implantation was insufficient because of the surgically induced corneal spherical aberration. Considering surgically induced corneal spherical aberration could improve the predictability of postoperative ocular spherical aberration.

Biconvex posterior chamber accommodating intraocular lens implantation after cataract surgery: long-term outcomes.

PURPOSE: To evaluate the long-term efficacy of a biconvex accommodating intraocular lens (IOL) to restore near visual performance. SETTING: Department of Ophthalmology, Keio University Hospital, Tokyo, Japan. METHODS: This 4-year study comprised eyes that had cataract surgery with implantation of a 1CU accommodating IOL. At all postoperative visits, the following were assessed: subjective spherical equivalent (SE) refraction; uncorrected (UDVA) and corrected (CDVA) distance visual acuities; uncorrected (UNVA), distance-corrected (DCNVA), and corrected (CNVA) near visual acuities; change in minimum additional (add) power (diopters) to attain CNVA; and accommodation amplitude. A questionnaire was administered at the last visit. RESULTS: Twelve eyes of 8 cataract patients (mean age 59.0 years +/- 18.4 [SD]) were evaluated. Postoperatively, the mean SE at 1 year and 4 years was significantly more hyperopic than at 1 month (P<.05). The mean UDVA increased significantly at 4 years compared with 1 month (P<.05). There were no significant changes in CDVA, UNVA, CNVA, and DCNVA throughout the follow-up period. The change in the minimum add power to attain CNVA and in the subjective and objective accommodation amplitudes also did not change significantly over time. Eighty-three percent of patients reported being satisfied with the results. CONCLUSION: Four years after implantation of an accommodating IOL, most patients had good vision and were satisfied, although the accommodation amplitude for near vision was not sufficient throughout the follow-up.

Effect of age on changes in anterior chamber depth and volume after laser in situ keratomileusis.

PURPOSE: To evaluate the effect of age on anterior chamber depth (ACD) and anterior chamber volume (ACV) after laser in situ keratomileusis (LASIK) for myopia. SETTING: Department of Ophthalmology, Keio University School of Medicine, and a private clinic, Tokyo, Japan. METHODS: In this retrospective study, patients who had uneventful LASIK for myopia or myopic astigmatism were divided into 2 groups: younger (younger than 40 years) and older (40 years and older). Central corneal thickness, central corneal true net power, ACV, and central ACD were measured using a rotating Scheimpflug camera preoperatively and 1 month postoperatively. These parameters were compared between the 2 groups. RESULTS: The study evaluated 161 eyes of 83 patients (mean age 34.5 years +/- 8.3 [SD]). The decreases in central ACD and ACV after LASIK were statistically significant in the younger group (P<.0001 and P = .0050, respectively) but not in the older group. CONCLUSION: Central ACD and the ACV decreased significantly after LASIK in younger patients (<40 years) but not in older patients, indicating that age influences changes in ACD and ACV after LASIK.