First results of cataract surgery and implantation of negative power intraocular lenses in highly myopic eyes

Improving the accuracy of the SRK/T formula in Chinese with implanting less than 10 D IOL calculated by the SRK/T formula: the SRK/T-Li formula

PURPOSE

To explore the accuracy of the improved SRK/T-Li formula in eyes following implantation of intraocular lens (IOL) of less than 10 D as calculated by using the SRK/T formula in Chinese.

METHODS

A total of 489 eyes from 489 patients with cataracts were included in this study. These patients were divided into a training set (271 patients) and a testing set (218 patients). The IOL power calculated by using SRK/T was less than 10 D. We evaluated the accuracy of the modified SRK/T-Li formula (P = PSRK/T × 0.8 + 2 (P = implanted IOL power; PSRK/T = IOL power calculated by SRK/T)). We evaluated the mean absolute error (MAE), percentage of prediction error (PE) within ± 0.25, ± 0.50, and ± 1.00 D, and the percentage of postoperative hyperopia.

RESULTS

The MAE values in order of lowest to highest were as follows: 0.412 D (SRK/T-Li), 0.414 D (Barrett Universal II, (BUII)), 0.814 D (SRK/T), and 1.039 D (Holladay 1). The percentage of PE within ± 0.25 D, ± 0.50 D, and ± 1.00 D was 38.99%, 69.27% and 92.66% (BUII), 40.83%, 69.27% and 94.04% (SRK/T-Li), 20.64%, 41.28% and 71.56% (SRK/T), and 7.34%, 16.51% and 53.21% (Holladay 1), respectively. SRK/T-Li had the smallest postoperative hyperopic shift.

CONCLUSIONS

For Chinese patients with an IOL power of less than 10 D as calculated by using the SRK/T, the SRK/T-Li has good accuracy and is the best choice to reduce postoperative hyperopic shift.

Intraocular lens power calculation for plus and minus lenses in high myopia using partial coherence interferometry

Purpose

We assessed the accuracy of lens power calculation in highly myopic patients implanting plus and minus intraocular lenses (IOL).

Methods

We included 58 consecutive, myopic eyes with an axial length (AL) > 26.0 mm, undergoing phacoemulsification and IOL implantation following biometry using the IOLMaster 500. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the Barrett Universal II (Barrett), Holladay I, Hill-RBF (RBF) and SRK/T formulae.

Results

The mean axial length was 30.17 ± 2.67 mm. Barrett (80%), Haigis (87%) and RBF (82%) showed comparable numbers of IOLs within 1 diopter (D) of target refraction. Visual acuity (BSCVA) improved (p < 0.001) from 0.60 ± 0.35 to 0.29 ± 0.29 logMAR (> 28-days postsurgery). The median absolute error (MedAE) of Barrett 0.49 D, Haigis 0.38, RBF 0.44 and SRK/T 0.44 did not differ. The MedAE of Haigis was significantly smaller than Holladay (0.75 D; p = 0.01). All median postoperative refractive errors (MedRE) differed significantly with the exception of Haigis to SRK/T (p = 0.6): Barrett − 0.33 D, Haigis 0.25, Holladay 0.63, RBF 0.04 and SRK/T 0.13. Barrett, Haigis, Holladay and RBF showed a tendency for higher MedAEs in their minus compared to plus IOLs, which only reached significance for SRK/T (p = 0.001). Barrett (p < 0.001) and RBF (p = 0.04) showed myopic, SRK/T (p = 002) a hyperopic shift in their minus IOLs.

Conclusions

In highly myopic patients, the accuracies of Barrett, Haigis and RBF were comparable with a tendency for higher MedAEs in minus IOLs. Barrett and RBF showed myopic, SRK/T a hyperopic shift in their minus IOLs.

Effect of fixation stability during biometry measurements on refractive prediction accuracy in highly myopic eyes

PURPOSE

To assess the effect of preoperative biometry fixation stability on postoperative refractive errors in highly myopic cataractous eyes.

SETTING

Eye and ENT Hospital of Fudan University, Shanghai, China.

DESIGN

Prospective cohort study.

METHODS

Eyes of highly myopic patients and emmetropic controls were included. Routine ophthalmologic examinations and measurement of fixation stability in the 63% and 95% bivariate contour ellipse areas (BCEAs) were conducted preoperatively. The refractive error from prediction was calculated 1 month postoperatively with the SRK/T and Holladay 1 formulas. Univariate and multivariable analyses were performed to identify the factors associated with postoperative refractive errors.

RESULTS

The refractive errors were more widely distributed in the 45 highly myopic eyes than in the 40 emmetropic control eyes: SRK/T, +0.15 diopter [D] ± 0.80 [SD] and -0.16 ± 0.35 D, respectively; Holladay 1, +0.54 ± 0.79 D and -0.23 ± 0.34 D, respectively. In the highly myopic group, 63% BCEA was correlated with axial length (AL) (P = .021) and posterior subcapsular opacity grade (P = .040). With both formulas, refractive errors and absolute refractive errors were positively correlated with 63% BCEA: SRK/T, P = .010 and P = .001, respectively; Holladay 1, P = .006 and P = .003, respectively. Backward multiple linear regression analysis showed that with both formulas, AL and 63% BCEA were significantly associated with postoperative refractive errors.

CONCLUSION

Poor preoperative biometry fixation stability correlated with long AL and severe posterior subcapsular opacity contributed to significant deviation of refractive errors after cataract surgery in highly myopic eyes.

Intraoperative aberrometry versus preoperative biometry for intraocular lens power selection in axial myopia

PURPOSE

To compare the accuracy of intraoperative wavefront aberrometry (ORA) and the Hill-radial basis function (RBF) formula with other formulas based on preoperative biometry in predicting residual refractive error after cataract surgery in eyes with axial myopia.

SETTING

Private practice, Harrisburg, Pennsylvania, USA.

DESIGN

Retrospective consecutive case series.

METHODS

Eyes with an axial length (AL) greater than 25.0 mm had cataract extraction with intraocular lens implantation. For each eye, the 1-center Wang-Koch AL-optimized Holladay 1 formula was used to select an IOL targeting emmetropia. Residual refractive error was predicted preoperatively using the SRK/T, Holladay 1 and 2, Barrett Universal II, and Hill-RBF formulas and intraoperatively using wavefront aberrometry. The postoperative refraction was compared with the preoperative and intraoperative predictions.

RESULTS

The study comprised 37 patients (51 eyes). The mean numerical errors ± standard error associated with using the SRK/T, Holladay 1, AL-optimized Holladay 1, Holladay 2, Barrett Universal II, and Hill-RBF formulas and intraoperative wavefront aberrometry were 0.20 ± 0.06 diopters (D), 0.33 ± 0.06 D, -0.02 ± 0.06 D, 0.24 ± 0.06 D, 0.19 ± 0.06 D, 0.22 ± 0.06 D, and 0.056 ± 0.06 D, respectively (P < .001). The proportion of patients within ±0.5 D of the predicted error was 74.5%, 62.8%, 82.4%, 79.1%, 73.9%, 76.7%, and 80.4%, respectively (P = .090). Hyperopic outcomes occurred in 70.6%, 76.5%, 49.0%, 74.4%, 76.1%, 74.4%, and 45.1% of the eyes, respectively (P = .007).

CONCLUSIONS

Intraoperative wavefront aberrometry was better than all formulas based on preoperative biometry and as effective as the AL-optimized Holladay 1 formula in predicting residual refractive error and reducing hyperopic outcomes. The Hill-RBF formula's performance was similar to that of the fourth-generation formulas.

Ocular biometry and refractive outcomes using two swept-source optical coherence tomography-based biometers with segmental or equivalent refractive indices

This study compared the axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), mean anterior corneal radius of curvature (Rm), and postoperative refractive outcomes obtained from two different swept-source optical coherence biometers, the ARGOS (Movu, Nagoya, Japan), which uses the segmental refractive index for each segment, and the IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany), which uses an equivalent refractive index for the entire eye. One hundred and six eyes of 106 patients with cataracts were included. The refractive outcomes using the Barrett Universal II, Haigis, Hoffer Q, and SRK/T formulas were evaluated. The mean AL, CCT, ACD, and Rm differed significantly (P < 0.001) with the IOLMaster 700 (25.22 mm, 559 µm, 3.23 mm, and 7.69 mm) compared with the ARGOS (25.14 mm, 533 µm, 3.33 mm, and 7.66 mm). The mean LTs did not differ significantly. The percentages of eyes within ±0.50 and ±1.00 diopter of the predicted refraction did not differ significantly (P > 0.05). The accuracy of the intraocular lens power calculations was clinically acceptable with both biometers, although the ocular biometry using these two biometers exhibited certain differences.

Fixation Characteristics in Highly Myopic Eyes: the Shanghai High Myopia Study

We enrolled 500 highly myopic eyes and 50 controls in this hospital-based prospective cohort study. The fixation ellipse angle and area in terms of the bivariate contour ellipse area (BCEA) were measured with Macular Integrity Assessment microperimetry. Optic disc tilt and rotation were evaluated with retinal images. The associations between fixation and optic disc changes were assessed. Both 63% and 95% BCEA correlated positively with axial length (AL) (both r = 0.230, P = 0.001) in highly myopic group, and were significantly higher than the control group (both P < 0.001). The direction of fixation ellipse presented clockwise rotation in the right eyes and anti-clockwise rotation in the left eyes with the increase of AL in highly myopic group (AL ≥30 vs <30 mm: OD 76.12 ± 51.17°: vs 90.60° ± 51.28°, P = 0.029; OS 94.73 ± 57.45° vs 87.82 ± 55.15°, P = 0.371). The angle between the long axis of the fixation ellipse and the long axis of the optic disc (Angle_F−D) distributed in various directions: 0–30° (34.6% almost parallel) ≈60–90° (34.4% almost vertical) >30–60° (31% oblique). Angle_F−D increased slightly with the AL (r = 0.105, P = 0.024). In highly myopic eyes, fixation stability decreased with the AL, and superior rotation of the fixation ellipse increased with AL. The long axis of fixation ellipse and the long axis of optic disc became less parallel to each other with increasing AL. Our data may provide clues for improvement of fixation evaluation designs of biometric instruments.

Intraocular lens power calculation in eyes with extreme myopia: Comparison of Barrett Universal II, Haigis, and Olsen formulas

PURPOSE

To compare the accuracy of the Barrett Universal II, Haigis, and Olsen formulas in calculating intraocular lens (IOL) power in eyes with extreme myopia.

SETTING

Eye and Ear, Nose, and Throat Hospital, Fudan University, Shanghai, China.

DESIGN

Prospective case series.

METHODS

Eyes were divided into 3 axial length (AL) groups as follows: 26.0 to 28.0 mm (control), 28.0 to 30.0 mm (extreme myopia 1), and 30.0 mm or more (extreme myopia 2). The mean error (ME) 1 month postoperatively was adjusted to zero by optimizing the lens factor; then, the median absolute errors (MedAEs) were compared between formulas. Factors associated with postoperative refractive errors were analyzed.

RESULTS

After optimization, the MEs of the Barrett Universal II, Haigis, and Olsen formulas were 0.04 diopter (D) ± 0.48 (SD), 0.04 ± 0.66 D, and 0.04 ± 0.52 D, respectively, and the MedAEs were 0.37 D, 0.46 D, and 0.39 D, respectively (P = .044; Haigis versus Barrett: P = .038). In the extreme myopia 1 group, all 3 formulas produced small MedAEs (P = .662). In the extreme myopia 2 group, the Haigis formula produced a significantly greater MedAE than the Barrett Universal II formula (P = .007; Haigis versus Olsen: P = .055). The accuracy of the Haigis formula in myopic eyes was affected by the AL and keratometry value, whereas the accuracy of the Barrett Universal II and Olsen formulas was affected by the AL only.

CONCLUSIONS

In eyes with an AL of 28.0 to 30.0 mm, all 3 formulas were accurate. In eyes with AL of 30.0 mm or more, the Barrett Universal II formula was better than the Haigis formula, possibly because there were fewer influencing factors.

Refractive outcomes of cataract surgery in primary congenital glaucoma

AIM

To evaluate refractive outcomes of cataract surgery with intraocular lens (IOL) implantation in operated eyes of primary congenital glaucoma (PCG).

DESIGN

A retrospective case-control study.

METHODS

Patients of PCG who developed cataract following trabeculectomy with trabeculotomy were recruited. Preoperative biometry was recorded and refractive outcomes of the patients in terms of spherical equivalent (SE) and prediction error were noted at 3 and at 12 months following surgery. The refractive outcomes were compared with non-glaucomatous eyes of children in similar age group who underwent lens aspiration with IOL implantation (controls).

RESULTS

The median age of the children with PCG (n = 31) at the time of cataract surgery was 60 months, similar to controls (n = 29); 48 months (p = 0.3). The SE in PCG eyes at 12 months was comparable to controls (p = 0.18). The prediction error (postoperative SE - predicted SE) at 3 months (p = 0.018) and at 12 months (p = 0.03) among PCG eyes was higher and more myopic compared with controls. The range of prediction error at 12 months in PCG eyes was - 8.6 to + 5.8 D (median - 2.0 D), whereas in controls it was - 4.2 to + 6.3 D (median + 0.5 D). For each mmHg intraocular pressure (IOP) increase there was 0.42 mm increase in axial length among PCG eyes and a 0.24 mm increase among controls (p < 0.001).

CONCLUSIONS

After IOL implantation there was a greater prediction error and a greater myopic shift among PCG eyes. Eyes of children with PCG are more prone to refractive surprises as their axial length changes are more sensitive to IOP fluctuation.

Accuracy of minus power intraocular lens calculation using OKULIX ray tracing software

PURPOSE

The purpose of this retrospective study was to assess the accuracy of minus power intraocular lens calculation using partial coherence interferometry and OKULIX ray tracing software.

METHODS

We included 25 consecutive, myopic eyes with axial length ≥ 30 mm (25 patients, 13 males and 12 females, and 57.6 ± 10.3 years old), which underwent phacoemulsification and implantation of a minus power intraocular lens in the capsular bag. Axial length measurement and corneal topography were performed using the OA-1000 optical biometer and Topographic Modeling System TMS-5, respectively. The IOL power was calculated using SRK/T formula and OKULIX ray tracing software. The implanted IOL power was chosen based on OKULIX ray tracing software calculation aiming for - 2 diopters (D) of myopia.

RESULTS

SRK/T calculated IOL power (- 6.3 ± 2.8 D) showed statistically significant difference compared to OKULIX calculated IOL power (- 4.7 ± 2.6 D), r_s 0.994 p < 0.001. The expected refraction with implanted IOL was - 1.7 ± 0.9 D based on OKULIX ray tracing software calculation. A statistically significant difference was reported between implanted IOL and OKULIX calculated IOL power (2.7 ± 1.4 D), r_s 0.981 p < 0.001. A statistically significant difference was reported between the expected refraction with implanted IOL and the achieved spherical refraction at 1 month postoperatively (1.4 ± 0.7 D), r_s 0.77 p < 0.001. The achieved spherical refraction at 1 month postoperatively was 0.2 ± 0.2 D.

CONCLUSIONS

Although OKULIX ray tracing software yielded more accurate minus power intraocular lens calculation in extreme myopia, compared to SRK/T formula, yet it still shows tendency toward hyperopia.

Fixation Stability and Refractive Error After Cataract Surgery in Highly Myopic Eyes

PURPOSE

To analyze the refractive error in highly myopic eyes after cataract surgery and investigate the possible impact of fixation stability on it.

DESIGN

Secondary data analysis from a previous prospective study.

METHODS

Clinical data of 98 eyes of 98 consecutive patients with high myopia and 42 eyes of 42 controls, which underwent cataract surgery, were analyzed. Refractive error was calculated 1 month after surgery based on both Sanders-Retzlaff-Kraff theoretic (SRK/T) and Holladay 1 formulas. Fixation stability was evaluated using the Macular Integrity Assessment microperimeter system, which assessed the fixation pattern in terms of 63% and 95% of the bivariate contour ellipse area (BCEA). Multiple linear regression analysis was performed to identify independent predictors of postoperative refractive error.

RESULTS

The highly myopic cataract group had greater hyperopic refractive errors (P < .001 for both formulas) and larger 63% and 95% BCEA values (P = .033 and P = .034) than the control group. In the highly myopic group, the factors 63% or 95% BCEA were positively correlated with the postoperative refractive error (SRK/T formula, r = 0.383, P < .001 and r = 0.320, P = .002, respectively). Multiple linear regression analysis showed that with the SRK/T formula, postoperative refractive error in highly myopic eyes was significantly correlated with axial length (β = 0.491, P < .001), 63% BCEA (β = 0.181, P = .045), and corneal curvature (β = -0.190, P = .024). The refractive error was no longer associated with corneal curvature after using the Holladay 1 formula.

CONCLUSIONS

Highly myopic eyes usually had hyperopic refractive errors after cataract surgery. Fixation stability might serve as an important determinant of postoperative refractive errors in this population.

Nd: YAG laser posterior capsulotomy rates in myopic eyes after implantation of capsular tension ring

Background

The aim f this study was to evaluate the effect of capsular tension ring implantation during cataract surgery on the incidence of neodymium: YAG (Nd: YAG) laser posterior capsulotomy in myopic (axial length [AL] ≥25.00 mm) eyes.

Material/Methods

In this retrospective study, the records of the cases of 117 myopic patients who underwent cataract surgery between January 2004 and January 2011 were reviewed. A total of 153 eyes with an axial length of 25 mm or higher were included in the study with consideration of exclusion criteria mentioned below. Eyes were grouped by presence or lack of capsular tension ring (CTR+ and CTR−, respectively).

Results

The study included 153 eyes from 107 myopic patients. Hydrophilic acrylic IOL and capsular tension ring (CTR) were implanted in 78 eyes (CTR+ group), and 75 eyes received only the hydrophilic acrylic IOL (CTR− group). Six eyes (7.6%) in CTR+ and 16 eyes (21.3%) in CTR− required Nd: YAG laser capsulotomy within 7 years. The difference between the 2 groups was statistically significant (p=0.021).

Conclusions

Because CTRs significantly decrease subsequent need for Nd: YAG laser posterior capsulotomy in myopic patients, are very inexpensive, and provide other benefits, our data suggest that the use of CTRs in myopic eyes undergoing cataract surgery with an hydrophilic acrylic IOL implantation is advantageous and should be standard practice.

A new technique for Nd:YAG laser posterior capsulotomy

AIM

To investigate the effects of a new opening pattern in neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy on visual function.

METHODS

This technique was conducted along a circular pattern. The energy ranged between 0.8 and 1.2 mJ/pulse was consumed and mean total energy levels were 74±21 mJ (mean±standard deviation: SD, from 40 to 167) and laser shots aimed at 150 µm away behind a datum point and went along an imaginary line which extends 0.5 mm inside from optic margin and into the circular en bloc pattern. Vitreous stands were attached with fragment and then they were cut off by the laser after circular application. The circular fragment was completely separated from vitreous, and then this fragment was quickly sunk in intravitreal space.

RESULTS

The follow-up period ranges from at least a week to 40mo, making 15.8mo on average. The procedural outcome showed 96% (74 eyes out of the 77 eyes) enhancement in patients' visual acuity. Cystoid macular edema or retinal detachment was not observed in any of the patients during follow-up periods.

CONCLUSION

This new technique is expected to improve the weaknesses that the conventional procedures have by adding the process to cut off vitreous stands attached with the fragment by the laser to the circular application.

Accuracy of intraocular lens power calculation in high myopia

Purpose

To study the accuracy of different recent intraocular lens (IOL) calculation formulas in predicting a target postoperative refraction ± 1.0D (Diopters) in patients with long eyes (axial length ≥ 26.0 mm) undergoing phacoemulsification.

Materials and Methods

This study comprised 127 eyes of 87 patients who presented with cataract and axial eye length ≥ 26 mm. Before phacoemulsification and IOL implantation; axial length measurement using immersion ultrasound A-scan technique, and autokeratometry with or without computerized corneal topography for K readings were done. The IOL power was calculated using four formulas, namely the SRK-T, Hoffer-Q, Holladay-2, and Haigis formulas. Four months after surgery, refraction was done. Differences between actual postoperative refraction and assumed target refraction using the different formulas were analyzed. P < 0.05 was considered statistically significant.

Results

In all 127 eyes, the mean axial length was 31.71 mm (range, 26.06–37.11 mm) and the mean K was 44.68 D (range, 40.05–55.14D). The mean preoperative spherical equivalent (SE) was −17.52D (range, −12.25 to −30.50D). After surgery, the mean spherical equivalent was −0.8 ± 0.83D (range, +1.25 to −3.75D). The mean postoperative refractive SE when implanting a plus power IOLs was −0.3 ± 0.51D (P < 0.001) while the mean postoperative refractive SE when implanting a minus power IOLs was +1.21 ± 0.11D denoting a highly significant tendency toward hyperopia (P < 0.001). Concerning the minus power group, most postoperative refractive error was within +1.0 to +2.0D in the actual implanted IOL and in all other formula calculated IOL power. However, Haigis formula showed the least deviation while SRK-T and other formulas showed a greater tendency toward hyperopia.

Conclusions

In eyes with high axial myopia, the performance of SRK-T, Hoffer-Q, Holladay-2 and Haigis formulas are comparable in low plus-powered IOL implantation. Haigis formula is the best formula when minus power IOL is implanted.

Intraocular lens power calculation and optimized constants for highly myopic eyes

PURPOSE

To determine the accuracy of intraocular lens (IOL) power calculations in eyes with high myopia and to suggest adjusted constants for these cases.

SETTING

Centre for Ophthalmology, Eberhard-Karls-University, Tuebingen, Germany.

METHODS

Patients with high myopia having phacoemulsification with implantation of an AcrySof MA60MA IOL (power range +5.00 to -5.00 diopters [D]) were evaluated. Optical biometry (IOLMaster) and IOL calculations were performed before and after IOL implantation. Because of different optic principal planes of negative-diopter and positive-diopter IOLs, separate constants were calculated for these groups.

RESULTS

Fifty eyes (32 patients) were evaluated. Thirty eyes (mean AL 31.15 mm +/- 1.69 [SD]) had implantation of a positive-diopter IOL (mean power +3.10 +/- 1.50 D) and 18 eyes (mean AL 33.20 +/- 2.25 mm), a negative-diopter IOL (mean power -3.20 +/- 1.70 D). Postoperatively, the mean spherical equivalent was -1.42 +/- 1.33 D and -0.41 +/- 1.81 D, respectively. The difference in optimized constants between positive- and negative-diopter IOLs was significant for all formulas. Power calculation with the SRK II formula showed a wide range of deviation of postoperative refraction from target refraction. Calculation with the Haigis, SRK/T, Holladay 1, and Hoffer Q formulas showed a mean deviation of 0.00 D with an SD of 0.88, 0.92, 1.03, and 1.15, respectively.

CONCLUSIONS

Results indicate that the SRK II formula cannot be recommended for IOL power calculation in highly myopic patients. With optimized constants, the SRK/T, Haigis, Hoffer Q, and Holladay 1 formulas produced small deviation of postoperative refraction from target refraction.

Efficacy and safety of cataract extraction with negative power intraocular lens implantation

Purpose:

To evaluate the visual and refractive outcomes, lens power calculation accuracy, and safety of negative power intraocular lenses (IOLs) implanted in highly myopic eyes at the time of cataract surgery.

Design:

Interventional case series.

Methods:

Sixteen consecutive highly myopic eyes implanted with IOLs from –1 D to –6 D were identified. IOL power; preoperative and postoperative best-corrected visual acuity (BCVA); postoperative uncorrected visual acuity (UCVA); preoperative, intended, and achieved spherical equivalent (SE) refractive errors; and operative complications were recorded.

Results:

Median UCVA improved from finger counting to 20/50-2. Median BCVA improved from 20/125-1 to 20/30+1. Mean axial length was 32.65 mm. The mean SE refractive error was –22.19 ± 5.4 D before surgery and -0.28 ± 1.4 D after surgery. The difference between the mean intended and mean achieved SE refractive errors was +1.16 D for the SRK/T, +1.2 D for the Holladay 1, and +1.60 D for the Hoffer Q formulas. Only 5 (33.3%) of 15 eyes in which postoperative measurements were possible were within 1 D of the intended SE postoperative refraction. Postoperative complications included a mildly hyperopic postoperative refractive error (+1.75 D) in one eye necessitating an IOL exchange and posterior capsule opacification in most eyes. There were no retinal detachments.

Conclusions:

The SRK/T formula had the greatest accuracy and predictability when immersion A-scan ultrasonography was used to measure axial length. The mean achieved postoperative refractive error was +1.16 D more hyperopic than predicted by this formula. We recommend targeting highly myopic eyes for –1.5 D using the SRK/T formula if a negative power IOL is calculated and emmetropia or mild residual myopia is the desired postoperative result.

[Apodized diffractive optic. New concept in multifocal lens technology]

As a consequence of improvement in intraocular lens (IOL) technology and the wish for presbyopia correction, modern multifocal IOLs are being implanted increasingly more often. The apodized diffractive optic represents a new design among multifocal IOLs. A comprehensive description of this principle with a review of current literature facilitates the understanding and correct application in IOL surgery.

Visual outcome after cataract surgery in extremely high axial myopia

We retrospectively investigated visual outcome after cataract surgery with implantation of zero or negative-power intraocular lenses (IOL) in 110 eyes with extremely high axial myopia. Extremely high axial myopes can benefit from cataract surgery and implantation of zero or negative-power IOLs with few complications. Factors associated with visual outcome included preoperative best-corrected visual acuity, gender, and age. Method of surgery did not influence the visual outcome.

Posterior capsule opacification in myopic eyes

PURPOSE

To determine whether posterior capsule opacification (PCO) is extensive in eyes with myopia or long axial length when an intraocular lens (IOL) of low-power, zero-power, or minus-power, is implanted.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

Ninety eyes of 90 patients scheduled for phacoemulsification surgery were recruited. These consisted of 30 eyes with high (> or =-8 diopters [D]) myopia, 30 eyes with moderate (<-8 D and > or =-3 D) myopia, and 30 eyes with low (<-3 D) myopia. All eyes had implantation of an acrylic IOL-low-power, zero-power, or minus-power-with a sharp optic edge (AcrySof MA60BM or MA60MA, Alcon Surgical). The PCO in these eyes was measured using a Scheimpflug videophotography system (EAS-1000, Nidek) 1, 3, 6, 12, 18, and 24 months after surgery. Visual acuity and the incidence of neodymium:YAG (Nd:YAG) laser posterior capsulotomy were also examined.

RESULTS

No significant difference was observed in the mean PCO value or in the Nd:YAG capsulotomy rate between the high myopia, moderate myopia, or low myopia groups throughout the follow-up period. There was also no significant correlation between PCO value and the actual spherical power or axial length of the eye. Furthermore, although mean visual acuity tended to be worse in proportion to the degree of myopia, the difference was not statistically significant.

CONCLUSION

When an acrylic IOL of low-power, zero-power, or minus-power with a sharp optic edge was implanted, high myopia and long axial length were not associated with the degree of PCO.

Biometry accuracy using zero- and negative-powered intraocular lenses

PURPOSE

To audit the accuracy of biometry using the SRK/T formula when negative- or zero-powered intraocular lenses (IOLs) are predicted and to compare the results between A-scan, B-scan, and optical methods of biometry.

SETTING

Moorfields Eye Hospital, London, United Kingdom.

METHODS

This retrospective analysis comprised 78 eyes of 54 patients having cataract surgery with zero- or negative-powered IOLs. Axial lengths were measured with A-scan, B-scan, applanation, or optical methods. Differences between SRK/T-predicted and actual postoperative refraction were analyzed for 75 eyes having cataract surgery. Ocular comorbidity, visual acuity, and biometry readings were also compared.

RESULTS

Forty-one percent of 75 patients analyzed were within +/-1.00 diopter (D) of the predicted refraction, although there was a significant tendency toward a hyperopic overcorrection by 1.14 D (95% confidence interval, 0.89-1.39 D). This overcorrection error was consistent across all 3 biometry methods used to estimate axial length and increased with the use of stronger (more negative) IOLs.

CONCLUSION

Surgeons should be aware of the tendency for negative-powered lenses to overcorrect and lead to a hyperopic outcome when using the SRK/T biometry formula in highly myopic eyes. A weaker-powered negative IOL is recommended to aim for a more myopic postoperative outcome by about 1.00 to 2.00 D.

Small incision clear lens extraction for correction of high myopia

PURPOSE

To evaluate the effectiveness, predictability, and safety of clear lens extraction in the correction of high myopia.

SETTING

Kartal Education and Research Hospital, Istanbul, Turkey.

METHODS

This retrospective study comprised 56 eyes of 30 patients who had clear lens extraction to correct myopia of 12.00 diopters (D) or more. Small incision clear lens extraction using an anterior chamber maintainer was performed and low-power posterior chamber intraocular lens (IOL) was implanted. The mean postoperative follow-up was 40.2 +/- 11.9 months.

RESULTS

Uncorrected visual acuity improved in 94.6% of eyes. Best-corrected visual acuity (BCVA) improved in 37 eyes (66%); 27 (48.2%) gained two or more lines. The percentage of eyes achieving a BCVA of 20/40 or better increased from 26.7% preoperatively to 58.9% postoperatively. Of the eyes, 38 (67.8%) were within +/- 1.00 D of targeted refractive error and 52 (92.8%) were within +/- 2.00 D. Posterior capsule tear with vitreous loss occurred in one eye (1.7%). During the follow-up, retinal detachment (RD) occurred in 2 eyes (3.5%).

CONCLUSIONS

Clear lens extraction and IOL implantation was effective and had an acceptable predictability and a low morbidity in correcting high myopia. Regular retinal examination is necessary to prevent postoperative RD.

Use of Nd:YAG laser capsulotomy

Surgery for cataract removal has become successively refined such that posterior capsular opacification is the most common problem presenting after modern cataract extraction. Various techniques and treatments exist to manage patients with posterior capsular opacification using Nd:YAG capsulotomy. There are many possible variations in initial assessment, pre-laser treatments, laser techniques, and follow-up routines. The literature on the use of Nd:YAG laser for capsulotomy was reviewed and interpreted. This article presents the currently available knowledge in a format that allows the practitioner to tailor an evidence-based protocol for treating patients with symptomatic posterior capsule opacification.

Anterior chamber intraocular lens for high myopia: five year results

PURPOSE

To evaluate the effectiveness of the surgical correction of high myopia 5 years after anterior chamber intraocular lens (IOL) implantation and to analyze the lens position and related complications.

SETTING

Federal University of São Paulo-Escola Paulista de Medicina, São Paulo, Brazil.

METHODS

This prospective study comprised 26 eyes that were implanted with an anterior chamber IOL (model ZB5M) and had a minimum follow-up of 5 years. Before and after surgery, manifest and cycloplegic refractions were done; slitlamp examination was performed; anterior chamber depth was measured; and keratometry, ophthalmoscopy, and central corneal endothelial cell count were performed. At the last follow-up, computerized biomicroscopy of the anterior segment was also done.

RESULTS

The spherical equivalent decreased from -16.5 diopters (D) +/- 4.1 (SD) preoperatively to -0.9 +/- 0.9 D postoperatively. At the last examination, 57.7% of eyes had a spherical equivalent refraction within +/-1.0 D of emmetropia. Of eyes with a preoperative best spectacle-corrected visual acuity of 20/40 or better, 73.3% had an uncorrected visual acuity of 20/40 or better postoperatively. The mean tilt caused by the IOL was 4.4 +/- 2.7 degrees (range 0.5 to 12.2 degrees) and the mean IOL decentration, 0.3 +/- 0.2 mm (range 0.02 to 0.8 mm). The mean decrease in the endothelial cell count was 1.5%, with a mean cell density of 2808 +/- 305 cells/mm2 preoperatively and 2765 +/- 242 cells/mm2 postoperatively. Pupillary ovalization was observed in 12 eyes (46.1%).

CONCLUSIONS

The anterior chamber IOL safely and effectively corrected high myopia.

Clear lens phacoemulsification for correction of high myopia

PURPOSE

To assess phacoemulsification and posterior chamber intraocular lens (IOL) implantation as an effective, safe, and predictable technique for the correction of high myopia.

SETTING

University Eye Clinic of Verona, Verona, Italy.

METHODS

A series of 25 eyes with myopia higher than -12.0 diopters (D) had clear lens extraction by phacoemulsification and IOL implantation in the capsular bag. The mean postoperative follow-up was 42.92 months +/- 3.76 (SD).

RESULTS

No serious intraoperative complications occurred. Uncorrected visual acuity improved in all cases. The mean postoperative best corrected visual acuity improved by an average of 1 line. One case (4.0%) of postoperative retinal detachment (RD) occurred at 12 months. One case (4.0%) of biometric error (3.0 D) occurred.

CONCLUSION

Clear lens extraction by phacoemulsification and IOL implantation in a series of highly myopic eyes was effective and had an acceptable predictability and a low rate of complications. Careful evaluation of the retinal periphery by indirect ophthalmoscopy is recommended to avoid postoperative RD.

Clear lens extraction and intraocular lens implantation in Marfan's syndrome

Intracapsular clear crystalline lens extraction and intraocular lens (IOL) implantation were performed in 4 highly myopic eyes of 2 patients with Marfan's syndrome. One eye of each patient received an anterior chamber IOL and the other, a scleral-fixated posterior chamber IOL. The preoperative spherical equivalent ranged between -14.50 and -28.00 diopters (D) and axial length range, between 25.32 and 36.02 mm. The SRK II formula was used. Mean uncorrected visual acuity improved from counting fingers to 20/80. Postoperative spherical equivalent correction ranged from -0.75 to +2.75 D. One eye had vitreous loss that was managed by anterior vitrectomy. Modern surgery for cataract and management of its complications suggest that clear crystalline lens extraction and IOL implantation can be attempted in selected cases with Marfan's syndrome.

Posterior capsule opacification. Part 2: Clinical findings

The incidence of posterior capsule opacification (PCO), the most common complication of modern cataract surgery with intraocular lens implantation, seems to have decreased slightly as a result of improved surgical and cortical cleanup techniques. However, the reported incidence is still significant. The diverse findings on PCO are the result in part of studies using different criteria to clinically judge and quantify the condition. In addition, the influence of intraocular and systemic factors are only now being identified. This second of a 2-part review of PCO focuses on (1) less subjective morphological and patient-dependent means to evaluate and quantify PCO; (2) the influence of ocular factors on PCO; (3) the influence of systemic factors on PCO; (4) available means and approaches to prevent or delay PCO.

Outcome of cataract surgery associated with posterior staphyloma

PURPOSE

To assess the outcome of cataract surgery in eyes with posterior staphyloma and identify predictors of surgical success.

SETTING

Tertiary care referral center.

METHODS

A retrospective analysis was conducted of 107 consecutive patients with posterior staphyloma and 107 control patients who had cataract surgery. Potential associations of preoperative variables with surgical success were analyzed using the chi-square test, multivariate linear regression, and Student t test.

RESULTS

The staphyloma group was younger, had more women, and had a lower mean visual acuity preoperatively than the control group. All patients in the control group and all but 1 in the staphyloma group had intraocular lens (IOL) implantation at the time of cataract extraction. The rates of posterior capsule tear and vitreous loss were similar in the staphyloma and control groups. There was 1 case each of retinal detachment and IOL dislocation in the staphyloma group. The staphyloma group had significantly lower postoperative visual acuity than the control group; however, the percentage in the staphyloma group with a visual acuity of finger counting or worse decreased from 80.4% preoperatively to 16.8% postoperatively and the percentage with an uncorrected visual acuity of 20/160 or better increased from 5.6% to 67.3%. Myopic degeneration was judged to be the cause of postoperative acuity worse than 20/100 in 22.4% in the staphyloma and 0% in the control group; other causes for poor postoperative acuity were similar in the 2 groups. In the staphyloma but not the control group, decreased postoperative acuity was independently associated with age greater than 65 years and axial length greater than 29.0 mm.

CONCLUSIONS

Myopic degeneration may limit the results of cataract extraction in up to one fourth of patients with posterior staphyloma. Nevertheless, a substantial improvement in mean visual acuity resulted that was not associated with a significant increase in surgical complications.

Clear lens extraction and implantation of negative-power posterior chamber intraocular lenses to correct extreme myopia

PURPOSE

To evaluate the effectiveness, predictability, and safety of clear lens extraction to correct extreme myopia.

SETTING

Clinica de Nuestra Señora de la Concepción, Fundación Jiménez Díaz, Madrid, Spain.

METHODS

This retrospective study comprised 26 eyes of 17 highly myopic patients who had clear lens extraction and implantation of a negative-power posterior chamber intraocular lens (IOL). The IOL power was calculated using the SRK/T formula. Analyzed were visual and refractive results and intraoperative and postoperative complications. Follow-up was at least 12 months in all cases.

RESULTS

Uncorrected visual acuity improved in all cases, with 80.77% of eyes achieving 20/100 or better and 42.30%, 20/40 or better. Best spectacle-corrected visual acuity (BSCVA) improved in 23 eyes (88.46%). The percentage of eyes achieving a BSCVA of 20/100 or better increased from 73.07% preoperatively to 92.30% postoperatively and the percentage achieving 20/40 or better, from 23.07 to 73.07%. Of the 26 eyes, 76.91% were within 1.00 diopter (D) of refractive error and 96.16% were within 2.00 D. No intraoperative complications occurred. Although postoperatively 3 eyes (11.53%) developed choroidal detachment and 5 (19.23%) had an intraocular pressure greater than 25 mm Hg, all had a favorable outcome. Four eyes (15.38%) developed posterior capsule opacification and had a neodymium:YAG laser posterior capsulotomy 6 months postoperatively. No retinal detachments were observed.

CONCLUSION

Clear lens extraction with negative-power IOL implantation using the SRK/T formula had good effectiveness, acceptable predictability, and a low morbidity in eyes with extreme myopia over a short follow-up. A longer follow-up with more cases is needed to assess the safety of the procedure.