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Comparison of Hoffer Q and Haigis Formulae for Intraocular Lens Power Calculation According to the Anterior Chamber Depth in Short Eyes

PURPOSE To compare the accuracy of the Hoffer Q and Haigis formulae according to the anterior chamber depth (ACD) in cases of short axial length (AL). DESIGN Retrospective cross-sectional study. METHODS A total of 75 eyes from 75 patients with an AL of less than 22.0 mm implanted with an Acrysof IQ intraocular lens (IOL) were enrolled. The median absolute errors (MedAEs) predicted by the Hoffer Q and Haigis formulae were compared. The correlations between ACD and the predicted refractive error calculated using the 2 formulae were analyzed. RESULTS There were no significant differences in the MedAEs predicted by the Hoffer Q and Haigis formulae (0.40 and 0.40 diopter [D], respectively). The difference between the refractive errors predicted by the Hoffer Q and Haigis formulae increased significantly as the ACD decreased (R(2) = 0.644, P < .001). The MedAE predicted by the Haigis formula (0.40 D) was significantly smaller than that predicted by the Hoffer Q formula (0.66 D) in eyes with an ACD of less than 2.40 mm (P = .027). There were no significant differences found between the MedAEs predicted by the Hoffer Q and Haigis formulae in eyes with an ACD of 2.40 mm or more. CONCLUSIONS The differences between the predicted refractive errors of the Hoffer Q and Haigis formula increased as ACD decreased in short eyes. Therefore, ACD should be taken into consideration when evaluating the accuracy of the IOL power calculation formulae in short eyes.

Use of corneal power-specific constants to improve the accuracy of the SRK/T formula.

PURPOSE To evaluate the effect of average corneal power (K) and axial length (AL) in a data-adjusted A-constant for improving the refractive outcome in the Sanders-Retzlaff-Kraff (SRK)/T formula. DESIGN Retrospective, consecutive, case series. PARTICIPANTS A total of 637 patients (637 eyes) who underwent uncomplicated phacoemulsification with implantation of the Acrysof IQ (IQ; Alcon, Fort Worth, TX; 314 eyes) or Akreos AO (AO; Bausch & Lomb, Rochester, NY; 323 eyes) intraocular lens (IOL) by a single surgeon. METHODS The correlation among the K, AL, and predicted refractive error in the SRK/T formula was analyzed. Patients were divided into 2 subgroups, the first to calculate the different data-adjusted A-constants based on the K and the second to compare the median absolute error (MedAE) based on different A-constants with the traditional A-constant in the SRK/T formula. MAIN OUTCOME MEASURES The data-adjusted A-constant and the MedAE (diopters [D]). RESULTS The data-adjusted A-constant showed a decreasing trend as K increased. The data-adjusted A-constant was 119.04 in the IQ group and 118.27 in the AO group. The calculated A-constant was 119.33 in the IQ group and 118.57 in the AO group when the cornea was flatter than 43.0 D and 43.2 D, respectively. The A-constant was 118.71 in the IQ group and 117.96 in the AO group when the cornea was steeper than or equal to 44.7 D and 45.0 D, respectively. The MedAE decreased from 0.29 D to 0.23 D in the IQ group (P = 0.001) and from 0.44 D to 0.38 D in the AO group (P < 0.001) when different A-constants were used. The MedAE further decreased from 0.36 D to 0.24 D in the IQ group (P = 0.005) and from 0.58 D to 0.37 D in the AO group (P < 0.001) when subjects with K 1.00 D or more above or 1.00 D below the most accurate K in each group were compared. CONCLUSIONS For a steep cornea, the calculated A-constant was smaller than that of the entire K, but for a flat cornea, a larger A-constant was calculated. Using different A-constants based on the K improved the refraction outcomes relying on the SRK/T formula.

Systemic Factors Associated with Central Serous Chorioretinopathy in Koreans

Purpose To investigate systemic factors associated with central serous chorioretinopathy (CSC). Methods We retrospectively reviewed the medical records of 113 Korean patients who were diagnosed with CSC and who underwent history taking with a specialized questionnaire for CSC. They were matched for age and gender at a ratio of 1 : 3 to 339 normal controls. Normal controls were consecutively selected from a database at the Health Promotion Center. General characteristics and medical histories were compared between the two groups. The statistical analyses used included independent t-test, Mann-Whitney test, Fishers exact test, and multivariate logistic regression analysis. Results There were 90 men and 23 women in the CSC group, and the male-female ratio for both groups was 3.9 : 1. The mean age of the patients was 45.6 years. In multivariate analysis, hypertension (odds ratio [OR], 2.327; 95% confidence interval [CI], 1.349-4.013), use of medicinal plants (OR, 2.198; 95% CI, 1.193-4.049), sleep disturbances (OR, 1.732; 95% CI, 1.096-2.739), and snoring (OR, 1.727; 95% CI, 1.058-2.820) were strongly associated with CSC. Conclusions Hypertension, sleep disturbance, snoring, and medicinal plant use were identified as factors associated with CSC. Expanded history taking, including systemic factors and culture-specific behavior related to stress or fatigue such as use of medicinal plants, will be helpful in identifying Korean patients at an increased risk for CSC.

Comparison of meibomian gland loss and expressed meibum grade between the upper and lower eyelids in patients with obstructive meibomian gland dysfunction

Purpose: The aim of this study was to compare meibomian gland loss (MGL) and expressed meibum grade between upper and lower eyelids in patients with obstructive meibomian gland dysfunction (MGD) and to evaluate the correlation between these 2 parameters and other clinical measurements. Methods: Twenty-six eyes of 26 patients with obstructive MGD were enrolled. Upper and lower MGLs were evaluated using noncontact meibography. Expressed meibum quality was assessed in 8 glands of the central third area of the upper and lower eyelids on a scale of 0 to 3 for each gland (total score range, 0–24). Tear film stability was evaluated based on tear break-up time (TBUT), and corneal staining was graded according to the National Eye Institute scale (range, 0–15). Results: The mean MGL in the lower eyelids (24.1% ± 10.8%) was significantly greater than that of the upper eyelids (11.2% ± 5.2%) (P < 0.001). The mean expressed meibum grade in the lower eyelids (16.5 ± 5.1) was also significantly larger than that of the upper eyelids (11.2 ± 5.2) (P < 0.001). MGL was significantly correlated with expressed meibum grade in both eyelids (r = 0.451, P = 0.021 in the upper eyelids; r = 0.626, P = 0.001 in the lower eyelids). The meibum grades of both the upper and lower eyelids were negatively correlated with TBUT and positively correlated with corneal staining score. However, the MGL in both the eyelids was not correlated with TBUT or with corneal staining score. Conclusions: In patients with obstructive MGD, MGL and meibum grade in the lower eyelids were significantly greater than those of the upper eyelids. Although MGL and meibum quality showed a positive correlation with each other, TBUT and corneal staining score were significantly correlated with only meibum grade, and not with MGL.

Effect of effective lens position on cylinder power of toric intraocular lenses

OBJECTIVE To evaluate the effects of effective lens position (ELP) on the corneal plane effective cylinder power of toric intraocular lenses (IOLs). DESIGN Retrospective cross-sectional study. PARTICIPANTS Ninety-four eyes from 78 patients who underwent uncomplicated phacoemulsification with implantation of an AcrySof toric IOL (1.50- to 3.00-D cylinder). METHODS The amount of corneal plane effective cylinder power of toric IOLs given by the manufacturer (target-induced astigmatism vector [TIA]) was compared with the postoperatively achieved cylindrical correction (surgically induced astigmatism vector [SIA]). The theoretical corneal plane cylinder power of toric IOLs was calculated according to ELP and corneal power using a refractive vergence formula. RESULTS The TIA (1.59 ± 0.43 D) was significantly smaller than the SIA (1.78 ± 0.65 D; p < 0.001). The difference between the magnitudes of SIA and TIA demonstrated a significant negative correlation with ELP (r = -0.219 and p = 0.034). The theoretical corneal plane cylinder power of toric IOLs demonstrated a decreasing trend as the ELP and corneal power increased. The range of changes in corneal plane effective cylinder power according to ELP and corneal power was greater in toric IOLs with high toricity. CONCLUSIONS The cylinder power of AcrySof toric IOLs should be adjusted according to ELP. For eyes with small ELP, the cylinder power should be reduced, and for eyes with large ELP, the cylinder power should be increased. The amount of reducing or increasing cylinder power of toric IOLs should be increased as the toricity increases.

Central corneal thickness and anterior scleral thickness in korean patients with open-angle glaucoma: An anterior segment optical coherence tomography study

PurposeTo assess the correlation between central corneal thickness (CCT) and anterior scleral thickness (AST) in Korean patients with normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). Patients and MethodsConsecutive patients with POAG, NTG, and normal individuals were recruited. Anterior segment optical coherence tomography (AS-OCT, Visante) was used to measure CCT and AST. The AST was measured 2 mm posterior to the scleral spur in the temporal meridian. Statistical analysis of the data included ANOVA and Pearson correlation analysis. ResultsOne hundred and eight participants (36 with NTG, 35 with POAG, and 37 normal individuals) were enrolled. The CCT (NTG 514.81±25.03 &mgr;m; POAG 534.43±34.79 &mgr;m; controls 536.70±32.11 &mgr;m) was found to be thinner in patients with NTG compared with POAG and the control eyes (P=0.023; P=0.009). The AST (NTG 738.53±53.63 &mgr;m; POAG 771.86±53.75 &mgr;m; controls 783.62±57.03 &mgr;m) was thinner in the patients with NTG compared with POAG and the normal controls (P=0.032; P=0.002). No significant difference in AST was found among the POAG and control eyes (P=0.636). A correlation between CCT and AST was found only among the patients with NTG (r=0.469, P=0.004). However, no correlation was observed between CCT and AST in patients with POAG and controls. ConclusionsAnterior scleral thickness was correlated with CCT in the NTG group, but this correlation was not observed among the POAG or control groups.

Comparison of SRK/T and Haigis formulas for predicting corneal astigmatism correction with toric intraocular lenses

Purpose To compare the accuracy of the SRK/T and Haigis formulas for predicting corneal astigmatism correction with a toric intraocular lens (IOL). Setting Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea. Design Retrospective cross‐sectional study. Methods Eyes with an Acrysof toric IOL were enrolled in the study. The corneal plane effective cylinder power of toric IOLs (target induced astigmatism vector [TIA]) predicted by the SRK/T and Haigis formulas were compared with the cylindrical correction achieved postoperatively (surgically induced astigmatism vector [SIA]). The magnitude of error was defined as the difference between the magnitudes of the SIA and TIA. The median absolute magnitudes of error predicted by the SRK/T and Haigis formulas were compared. The median absolute errors predicted by the 2 formulas were also compared. Results The mean postoperative SIA was 1.80 diopters (D) ± 0.55 (SD). The magnitude of error predicted by the SRK/T and Haigis formulas was 0.31 ± 0.40 D and 0.23 ± 0.40 D, respectively. The median absolute magnitude of error predicted by the Haigis formula was statistically significantly smaller than that predicted by the SRK/T formula (P < .001). The median absolute error predicted by the Haigis formula (0.35 D) was also statistically significantly smaller than that predicted by the SRK/T formula (0.43 D) (P = .003). Conclusion The Haigis formula was more accurate than the SRK/T formula not only in predicting the refractive outcome but also in predicting corneal astigmatism correction by toric IOLs. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Toric Intraocular Lens Calculations Using Ratio, of Anterior to Posterior Corneal Cylinder Power

PURPOSE To evaluate the accuracy of toric intraocular lens (IOL) calculation using estimated total corneal astigmatism based on the anterior-to-posterior corneal cylinder power ratio according to the axis orientation of anterior corneal astigmatism. DESIGN Retrospective cross-sectional study. METHODS Nine hundred twenty-eight eyes of 928 reference subjects and 20 cataract patients (20 eyes) implanted with a toric IOL were enrolled. Linear regression analysis parameters (β0 and β1) of relationship between the simulated keratometry cylinder (CylSimK) and posterior corneal cylinder power of reference subjects were used to calculate the estimated posterior corneal astigmatism (-[β1 × CylSimK + β0] @ 90). When regression analysis was not significant, estimated posterior corneal astigmatism was defined as the negative value of the mean posterior corneal cylinder power @ 90. Estimated total corneal astigmatism was defined as the vectorial sum of anterior corneal astigmatism and estimated posterior corneal astigmatism. Residual astigmatism error, predicted using SimK, was compared with that predicted using estimated total corneal astigmatism. RESULTS Estimated posterior corneal astigmatism was determined to be -(0.15 × CylSimK + 0.22) @ 90 in eyes with with-the-rule astigmatism, -(0.05 × CylSimK + 0.27) @ 90 in oblique astigmatism, and -0.27 @ 90 in against-the-rule astigmatism. The median magnitude of the predicted residual astigmatism error calculated using estimated total corneal astigmatism (0.30 cylinder diopters) was significantly smaller than that calculated with SimK (0.50 cylinder diopters). CONCLUSIONS Toric IOL calculations using estimated total corneal astigmatism based on the anterior-to-posterior corneal cylinder power ratio provided a more appropriate toric IOL cylinder power than calculations using SimK astigmatism.

Comparison of the actual amount of axial movement of 3 aspheric intraocular lenses using anterior segment optical coherence tomography

Purpose To compare the mean effective lens position (ELP) and actual amount of axial movement of 3 aspheric intraocular lenses (IOLs) using anterior segment optical coherence tomography (AS‐OCT). Setting Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea. Design Retrospective comparative study. Methods Consecutive patients had phacoemulsification with aspheric IOL implantation. The ELP measurements by AS‐OCT were taken 1 week and 1, 3, and 6 months postoperatively. The ELPRMS was defined as the root mean square (RMS) of the change in ELP at each follow‐up timepoint. Results An XL Stabi ZO 3‐plate IOL was implanted in 30 eyes, an Acrysof IQ C‐loop IOL in 22 eyes, and an Akreos MI‐60 4‐plate IOL in 17 eyes. The 4‐plate IOL showed significant changes in the mean ELP from 1 week to 1 month and from 3 to 6 months postoperatively (P=.005 and P=.028, respectively). The changes of the other 2 IOLs were insignificant during the 3 postoperative visits. However, the mean ELPRMS of the C‐loop IOL (0.06 mm ± 0.31 [SD]) was smaller than that of the 3‐plate IOL (0.14 ± 0.28 mm) and the 4‐plate IOL (0.20 ± 0.35 mm) (P=.014 and P=.023, respectively) during the 3 timepoints. Conclusion An appropriate method based on the actual amount of axial IOL movement, such as the ELPRMS, is needed to assess the axial positional stability of IOLs. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Change in Efficiency of Aspheric Intraocular Lenses Based on Pupil Diameter

PURPOSE To measure the effect of spherical aberration correction by aspheric intraocular lenses (IOLs) based on pupil diameter, and to determine the minimum pupil diameter for each aspheric IOL. DESIGN Retrospective cross-sectional study. METHODS Eight-six patients (169 eyes) who were implanted with a HOYA AF-1 NY-60 (HOYA Corporation) or Tecnis ZCB00 1-piece IOL (Abbott Medical Optics Inc) were enrolled. Ocular, corneal, and internal spherical aberrations were measured at the 1-month postoperative visit using the Wavefront Analyzer KR-1W (Topcon). Minimum pupil diameter, which is required for each aspheric IOL to be effective, was calculated using a regression equation. RESULTS The mean value of internal spherical aberration of the Tecnis ZCB00 group (-0.09 ± 0.094 μm) was lower than that of the HOYA NY-60 group (-0.05 ± 0.072 μm) (P = .005). The original negative spherical aberrations of the HOYA NY-60 (-0.18 μm) were measured at a pupil diameter of 5.6 mm, and for the Tecnis ZCB00 (-0.27 μm) at a pupil diameter of 6.1 mm. The aspheric IOL efficiency dropped to 0% when the pupil diameter was 3.47 mm for the Tecnis ZCB00 group and 3.71 mm for the HOYA NY-60 group. CONCLUSIONS When the pupil diameters of patients are smaller than 3.4 mm for the Tecnis ZCB00 and 3.7 mm for the HOYA NY-60, the spherical aberration correction using these aspheric IOLs seems to be ineffective. Approximately 10% of the eyes showed smaller pupil size than the minimum effective diameter under mesopic conditions.