Optical coherence tomography assessment of capsule closure after cataract surgery

Dynamic Changes of Capsular-Intraocular Lens Adhesion in Plate-Haptic Hydrophilic and Loop-Haptic Hydrophobic Eyes

INTRODUCTION

The aim of this work is to investigate the dynamic changes of capsular-intraocular lens (IOL) adhesion in plate-haptic hydrophilic and loop-haptic hydrophobic eyes.

METHODS

Cataract eyes that met the inclusion criteria were randomly assigned to receive implantation of a plate-haptic hydrophilic or loop-haptic IOL. The anterior capsular adhesion, posterior capsular adhesion, and the configurations of the capsular bend were evaluated using swept-source optical coherence tomography at 1 day, 1 week, 1 month, and 3 months postoperatively.

RESULTS

In total, 66 eyes of 66 patients were eligible for the analysis: 33 in the plate-haptic group and 33 in the loop-haptic group. The contact between the anterior capsule and IOL in the plate-haptic group was earlier than that in the loop-haptic group upon comparing the measurements taken at 1 day and 1 week (p = 0.001, p = 0.003, respectively). The complete attachment of the posterior capsule and IOL in the plate-haptic group was significantly greater at 1 week, 1 month, and 3 months (p = 0.001, p = 0.000, p = 0.001, respectively). The capsular bend index of the plate-haptic group was significantly greater than that of the loop-haptic group at each time points except at 1 day (p = 0.007, p = 0.049, p = 0.005, respectively). Furthermore, a new type of capsular bend, "cocked adhesion," was observed in the plate-haptic eyes.

CONCLUSIONS

The plate-haptic IOL demonstrated excellent capsular adhesion compared to the loop-haptic IOL, which was probably attributed to haptic compressibility. A special cocked configuration of the capsular bend in plate-haptic IOL was observed for the first time. Further studies are warranted to confirm the effect of the new type of capsular bend.

Three-dimensional assessment of posterior capsule-intraocular lens interaction with and without primary posterior capsulorrhexis: an intraindividual randomized trial

PURPOSE

To assess the morphologic and clinical features of posterior capsule-intraocular lens (IOL) interaction following cataract surgery with and without primary posterior continuous curvilinear capsulorrhexis (PPCCC) at a three-dimensional (3-D) level using Scheimpflug imaging.

METHODS

This prospective intraindividual randomized comparative study comprised 56 patients (112 eyes) with age-related cataract who had bilateral cataract surgery and hydrophobic acrylic IOLs implantation. In randomized order, cataract surgery with PPCCC was performed in 1 eye (PPCCC group), and the posterior capsule was left intact in the fellow eye (NPCCC group). Scheimpflug imaging containing 25 images distributed in 360° was taken 1 day, 1 week, 1 month, and 3 months postoperatively.

RESULTS

46 patients completed 3 months follow-up. Posterior capsule-IOL interaction can be morphologically classified into two types including complete adhesion and floppy shape in PPCCC group, and six types including full area wave, full area flat, concentric ring wave, concentric ring flat, sector, and complete adhesion in NPCCC group. The adhesion index (AI), defined as the proportion of complete adhesion of posterior capsule-IOL in 25 cross-section tomograms, was 0.45 ± 0.45, 0.79 ± 0.37, 0.92 ± 0.26 and 1.00 ± 0.00 in PPCCC group, while 0.05 ± 0.18, 0.41 ± 0.47, 0.87 ± 0.34, and 0.96 ± 0.21 in NPCCC group at 1 day, 1 week, 1 month and 3 months postoperatively, respectively (p = 0.001, 0.001, 0.338 and 0.151).

CONCLUSIONS

3-D Scheimpflug imaging was favorable in observing of posterior capsule-IOL interaction. Faster posterior capsule adhesion to the IOL was found in PPCCC group than in NPCCC group.

Effect of time and temperature-dependent changes of IOL material properties on IOL: Lens capsule interactions

Posterior Capsule Opacification (PCO) is the most common complication associated with Intraocular Lens (IOL) implantation. Based on the assumption that the interactions between an IOL and the lens capsule (LC) may influence the extent of PCO formation, a new in vitro model was developed to quantify the adhesion force of an IOL to simulated LC using a custom-designed micro-force tester. Using this system, we examined the influence of temperature (room temperature vs. body temperature) and incubation time (0 vs. 24 h) on the adhesion force between IOLs and LCs. The results show that, in line with clinical observations of PCO incidence, the adhesion force increased at body temperature and with increase in incubation time in the following order, Acrylic foldable IOLs > Silicone IOLs > PMMA IOLs. By examining the changes of surface properties as a function of temperature and incubation time, we found that acrylic foldable IOLs showed the largest increase in their hydrophilicity and reported the lowest surface roughness in comparison to other IOL groups. Coincidentally, using a newly established macromolecular dye imaging system to simulate cell migration between IOLs and LC, we observed that the amount of macromolecular dye infiltration between IOLs and LCs was in the following order: PMMA IOLs > Silicone IOLs > Acrylic foldable IOLs. These results support a new potential mechanism that body temperature, incubation time, surface hydrophilicity and smoothness of IOLs greatly contribute to their tight binding to LCs and such tight binding may lead to reduced IOL: LC space, cell infiltration, and thus PCO formation.

Assessment of tilt and decentration of crystalline lens and intraocular lens relative to the corneal topographic axis using anterior segment optical coherence tomography

Purpose

To investigate the tilt and decentration of the crystalline lens and the intraocular lens (IOL) relative to the corneal topographic axis using anterior segment ocular coherence tomography (AS-OCT).

Methods

A sample set of 100 eyes from 49 subjects (41 eyes with crystalline lenses and 59 eyes with IOLs) were imaged using second generation AS-OCT (CASIA2, TOMEY) in June and July 2016 at Okayama University. Both mydriatic and non-mydriatic images were obtained, and the tilt and decentration of the crystalline lens and the IOL were quantified. The effects of pupil dilation on measurements were also assessed.

Results

The crystalline lens showed an average tilt of 5.15° towards the inferotemporal direction relative to the corneal topographic axis under non-mydriatic conditions and 5.25° under mydriatic conditions. Additionally, an average decentration of 0.11 mm towards the temporal direction was observed under non-mydriatic conditions and 0.08 mm under mydriatic conditions. The average tilt for the IOL was 4.31° towards the inferotemporal direction relative to the corneal topographic axis under non-mydriatic conditions and 4.65° in the same direction under mydriatic conditions. The average decentration was 0.05 mm towards the temporal direction under non-mydriatic conditions and 0.08 mm in the same direction under mydriatic conditions. A strong correlation was found between the average tilt and decentration values of the crystalline lens and the IOL under both non-mydriatic and mydriatic conditions (all Spearman correlation coefficients, r ≥ 0.800; all P < 0.001).

Conclusion

When measured using second generation AS-OCT, both the crystalline lens and the IOL showed an average tilt of 4–6° toward the inferotemporal direction relative to the corneal topographic axis and an average decentration of less than 0.12 mm towards the temporal direction. These results were not influenced by pupil dilation and they showed good repeatability.

An Optical Section-Assisted In Vivo Rabbit Model for Capsular Bend and Posterior Capsule Opacification Investigation

Purpose

To establish an optical section-assisted in vivo rabbit model for capsular bend and posterior capsule opacification (PCO) investigation.

Methods

A total of 10 rabbits underwent phacoemulsification surgery and intraocular lens (IOL) implantation. On the basis of the relationship between the anterior capsule and IOL, the rabbits were divided into complete overlap and incomplete overlap groups, in which six and four rabbits were included, respectively. The capsular bend optical sections were assessed using ultra-long scan depth optical coherence tomography (UL-OCT), and posterior capsule opacification was evaluated with slit lamp on postoperative day 3, 7, 14, and 28. In addition, histopathological section was used to verify the accuracy of capsular bend type captured by OCT in three rabbits.

Results

Based on the special animal model, six capsular bend types were observed, namely, anterior (A), middle (M), posterior (P), detachment (D), funnel (Fun) and furcate adhesion (Fur). On day 3, capsular bend began to form. On 14 days, the capsular bends were comprised of A, M and D types, which were almost maintained until day 28. Histopathological section findings were consistent with optical sectioning results. In the incomplete and complete groups, the earliest PCO within the optical zone were on day 7 and 28, respectively. The incomplete group exhibited higher incidence and faster PCO on day 7 (p = 0.038) and 14 (p = 0.002).

Conclusions

This animal model not only mimics capsular bend evolution and PCO processes but also produces OCT optical section images equivalent to and more repeatable than histopathology, thereby providing a promising method for the further investigations of PCO.

The Repeatability Assessment of Three-Dimensional Capsule-Intraocular Lens Complex Measurements by Means of High-Speed Swept-Source Optical Coherence Tomography

Purpose

To rebuild the three-dimensional (3-D) model of the anterior segment by high-speed swept-source optical coherence tomography (SSOCT) and evaluate the repeatability of measurement for the parameters of capsule-intraocular lens (C-IOL) complex.

Methods

Twenty-two pseudophakic eyes from 22 patients were enrolled. Three continuous SSOCT measurements were performed in all eyes and the tomograms obtained were used for 3-D reconstruction. The output data were used to evaluate the measurement repeatability. The parameters included postoperative aqueous depth (PAD), the area and diameter of the anterior capsule opening (Area and D), IOL tilt (IOL-T), horizontal, vertical, and space decentration of the IOL, anterior capsule opening, and IOL-anterior capsule opening.

Results

PAD, IOL-T, Area, D, and all decentration measurements showed high repeatability. Repeated measure analysis showed there was no statistically significant difference among the three continuous measurements (all P > .05). Pearson correlation analysis showed high correlation between each pair of them (all r >0.90, P<0.001). ICCs were all more than 0.9 for all parameters. The 95% LoAs of all parameters were narrow for comparison of three measurements, which showed high repeatability for three measurements.

Conclusion

SSOCT is available to be a new method for the 3-D measurement of C-IOL complex after cataract surgery. This method presented high repeatability in measuring the parameters of the C-IOL complex.

Clinical outcomes and rotational stability of a 4-haptic toric intraocular lens in myopic eyes

PURPOSE

To evaluate the refractive outcomes and rotational stability of a 4-haptic toric intraocular lens (IOL) in myopic eyes and the correlations between IOL rotation and refractive sphere, axial length (AL), and white-to-white (WTW) diameter.

SETTING

Eye Clinic, Careggi Hospital, Florence, Italy.

DESIGN

Prospective case series.

METHODS

Phacoemulsification cataract extraction and implantation of an AT Torbi 709M IOL were performed. Corneal astigmatism was 1.50 diopters (D) or greater and the AL between 25.0 mm and 27.0 mm in all eyes. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, and IOL axis were evaluated preoperatively and postoperatively up to 6 months.

RESULTS

The study enrolled 20 eyes (20 patients). The UDVA and CDVA improved significantly postoperatively (P<.001). The mean refractive spherical equivalent decreased significantly from -7.10 D±1.78 (SD) preoperatively to -0.55±0.25 D 1 day postoperatively (P<.001) and remained stable thereafter. Vector analysis showed that 90% and 85% of the eyes were within ±0.25 D for J0 and J45, respectively. At 3 months and 6 months, the mean IOL rotation was 2.66±1.53 degrees and 3.00±1.69 degrees, respectively (P<.001), with 95% of eyes and 90% of eyes, respectively, within ±5 degrees. A positive correlation was found between IOL rotation and preoperative sphere; none was found with AL and WTW.

CONCLUSIONS

Implantation of the 4-haptic toric IOL in myopic eyes was effective and safe. The IOL showed no significant rotation over the 6-month follow-up.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Capsular adhesion to intraocular lens in highly myopic eyes evaluated in vivo using ultralong-scan-depth optical coherence tomography

PURPOSE

To evaluate the in vivo capsular apposition to the intraocular lens (IOL) in subjects with high myopia by ultralong-scan-depth optical coherence tomography (OCT).

DESIGN

Prospective observational case series.

METHODS

Forty eyes from 40 cataract patients scheduled for phacoemulsification surgery at the Affiliated Eye Hospital, Wenzhou Medical College were studied, of which 20 eyes were highly myopic (axial length >26 mm) and 20 eyes were emmetropic (22 mm < axial length <24.5 mm). All eyes were examined with a custom-built ultralong-scan-depth OCT at 4 hours, 1 day, 7 days, 14 days, and 28 days after surgery.

RESULTS

Anterior capsule contact with the IOL was significantly delayed in highly myopic eyes. Complete apposition of the posterior capsule with the IOL was significantly less common among highly myopic eyes than in emmetropic eyes (4 vs 16 eyes; P = .001). Posterior capsule adhesion to the IOL was inversely correlated with axial length (r = -0.494, P < .001, nonparametric Spearman test). The 3 types of complete adhesive capsular bend configurations observed were classified as anterior adhesion, middle adhesion, and posterior adhesion. Incomplete adhesion patterns were classified as funnel adhesion, parallel adhesion, and furcate adhesion. Five highly myopic eyes had slight posterior capsule opacification (PCO) at the last follow-up, as did 1 emmetropic eye.

CONCLUSIONS

Ultralong-scan-depth OCT revealed weak capsular adhesion and incompletely adhesive types of capsular bend in highly myopic eyes. These features presumably increase the likelihood of PCO during the early postoperative period.

Anterior segment optical coherence tomography in the assessment of postoperative intraocular lens optic changes

PURPOSE

To evaluate the use of anterior segment optical coherence tomography (AS-OCT) to assess postoperative intraocular lens (IOL) optic changes.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

DESIGN

Experimental study.

METHODS

Intraocular lenses explanted because of various complications were used, including poly(methyl methacrylate) (PMMA) IOLs with snowflake degeneration, hydrophilic acrylic IOLs with calcification, a silicone IOL with calcification from an eye with asteroid hyalosis, and hydrophobic acrylic IOLs explanted because of decentration, subluxation, or uveitis-glaucoma-hyphema syndrome. After gross and light microscopy, the IOLs were examined in the dry and hydrated states using AS-OCT. Selected hydrophilic acrylic IOLs were stained for calcium. In-the-bag IOLs in pseudophakic cadaver eyes were also evaluated by AS-OCT before and after explantation to confirm correspondence with the clinical situation.

RESULTS

Intraoptic changes, such as snowflake lesions in PMMA IOLs, calcification in hydrophilic acrylic IOLs, and glistenings in hydrophobic acrylic IOLs, could be imaged by AS-OCT. The method was also helpful in analyzing the location and density. However, in cases of more superficial changes, unless the lesions/deposits were present on the optic surface with an extension to the optic substance of at least 0.1 mm, they could not be clearly differentiated from the overall outline of the IOL surface.

CONCLUSIONS

Anterior segment OCT may be helpful in assessing the presence, location, and density of intraoptic changes, avoiding a misdiagnosis of IOL opacification and the performance of unnecessary procedures, such as posterior capsulotomy or vitrectomy.

Effect of delivery of MMP inhibitors from PDMS as a model IOL material on PCO markers

Posterior capsule opacification (PCO) or secondary cataract formation, following intraocular lens implantation, is a significant complication affecting an estimated 28% of cataract patients. Matrix metalloproteinases (MMPs) have been demonstrated to play a role in the formation of anterior subcapsular cataracts and it has been shown that the presence of MMP inhibitors (MMPI) decreases subcapsular cataract formation ex vivo. Since the mechanisms responsible for anterior subcapsular cataract formation and posterior capsule opacification are similar, it is reasonable to suggest that MMP inhibitors may also mitigate PCO. One of the most effective ways of delivering the inhibitors may be from the implanted intraocular lens (IOL) material itself. In the current work, delivery of three different MMP inhibitors from silicone rubber as a model IOL material was examined. Loading methods were developed which allowed continuous release of active MMPI for periods of over 5 months in some cases. Reduced migration rates were observed in human lens epithelial cells in vitro, suggesting that an effect on PCO may be possible. While further studies are necessary to tune the systems to achieve the desired rates of release, this work demonstrates that delivery of MMPI from silicone IOL materials has the potential to decrease the incidence of PCO.

Posterior capsule opacification in silicone and hydrophobic acrylic intraocular lenses with sharp-edge optics six years after surgery

PURPOSE

To compare posterior capsule opacification (PCO) between 2 three-piece intraocular lenses (IOLs) both with sharp-optic edges and open loop haptics, one made of silicone and the other made of hydrophobic acrylate, 6 years after surgery.

DESIGN

Randomized, controlled, patient- and examiner-masked trial with intra-patient comparison.

METHODS

One hundred and six eyes in 53 patients were included initially. Forty-four eyes of 22 patients with age-related bilateral cataract were available for the 6 years follow-up. Each patient had standard cataract surgery and randomly received a silicone (CeeOn 911A; AMO, Santa Ana, California, USA) or hydrophobic acrylic (AcrySof MA60BM; Alcon, Fort Worth, Texas, USA) IOL in the first eye, the other type of IOL in the fellow eye. Follow-up examinations were at 1, 3, and 6 years after surgery. The intensity of posterior capsule opacification (PCO) was assessed using digital retro-illuminated photos and the "automated quantification of after-cataract" (AQUA) software. Neodymium-yttrium-aluminum-garnet-laser capsulotomies (YAG-LC) performed were noted.

RESULTS

Six years after surgery, the AQUA scores were 2.3 +/- 1.4 for the silicone and 3.8 +/- 2.0 for the acrylic IOLs (P = .0016). The acrylic IOL eyes also had a significant increase in AQUA score from the 3-year to the 6-year follow-up. YAG-LC were performed in 2 silicone and 6 acrylic IOLs (P = .01).

CONCLUSIONS

An angulated three-piece hydrophobic acrylic IOL had more PCO 6 years after surgery than a silicone IOL of otherwise similar design. Apart from an optic material effect, differences in haptic design and the degree of optic edge sharpness may play a role.

Macular thickness after uneventful cataract surgery determined by optical coherence tomography

BACKGROUND

Using standardized macular optical coherence tomography (OCT) in the postoperative period, subclinical changes in macular thickness can be detected. With this method, postoperative development of macular thickness in healthy eyes is evaluated. The repeatability of the method and the influence of selected surgical (phaco time and phaco energy) and biometric parameters (axial length and anterior chamber depth) on the results were assessed.

METHODS

In a prospective study, 33 patients without macular pathology in both eyes were examined. Phacoemulsification and intraocular lens (IOL) implantation was performed in one eye, and the contralateral eye served as control. OCT (StratusOCT; Zeiss, Dublin, CA, USA), mean minimal foveal thickness (MMFT) and mean foveal thickness (MFT) were measured preoperatively, at 1 day, 1 week and 6 weeks postoperatively. At these visits, the best-corrected visual acuity (BCVA) tests and slit-lamp examination were performed. To assess the influence on foveal thickness ocular axial length, anterior chamber depth, phacotime and energy were documented. Statistical analysis using parametric tests was carried out with standard statistical software (SPSS11, BIAS).

RESULTS

MMFT of the operated eyes and the intraindividual difference of MMFT increased significantly at one day (+12.31 +/- 24.2 microm, P < 0.001) and 6 weeks (+6.76 +/- 22.6 microm, P = 0.009). MFT in the operated eyes and intraindividual difference of MFT rose significantly at 1 day, 1 week and 6 weeks (1 day: +10.66 +/- 20.8 microm, P = 0,026; 1 week: +15.23 +/- 19.7 microm; 6 weeks: +17.33 +/- 14.81 microm, P < 0.001). Repeatability was better for MFT in controls (ICR = 0.92) than for MMFT in controls (ICR = 0.77). No clinical cystoid macular edema was diagnosed in this study. No correlation between macular thickening and visual acuity and selected surgical and biometrical parameters could be found.

CONCLUSIONS

After cataract surgery, a mild increase of foveal thickness without impact on visual acuity could be observed. This increase may be due to both subclinical changes and to influence of changes in media opacity on the measurement technique. Surgical and biometric parameters such as phacotime and energy and axial length did not correlate to the degree of macular thickening.

Contact inhibition of migrating lens epithelial cells at the capsular bend created by a sharp-edged intraocular lens after cataract surgery

PURPOSE

To investigate whether the lens epithelial cells (LECs) at the capsular bend created by a sharp-edged intraocular lens (IOL) are in the G(0) phase of the cell cycle.

SETTING

Nishi Eye Hospital, Osaka, Japan.

METHOD

A CeeOn Edge silicone IOL (AMO) with sharp edges was implanted in 1 eye and a PhacoFlex II silicone IOL (AMO) with rounded edges in the contralateral eye after standard cataract surgery in 6 rabbits. Immunohistochemical staining for the Ki-67 antibody was performed 1 day, 3, 4, and 7 weeks after surgery.

RESULTS

In eyes with the sharp-edged IOL, LECs with thin, elongated nuclei accumulated at, but did not extend beyond, the capsular bend and stained negative for the Ki-67 antibody, indicating that they were in the G(0) phase of the cell cycle. In contrast, in the eye with the round-edged IOL, continuous migration of a predominantly monolayer of LECs over the IOL and onto the posterior capsule occurred. These cells were Ki-67 positive, indicating that they were proliferating.

CONCLUSIONS

Lens epithelial cells at the capsular bend of sharp-edged IOLs were in the G(0) phase of the cell cycle, indicating that they were contact inhibited. These findings support the theory the sharp posterior optic edge of the IOL inhibits LEC migration, reducing formation of posterior capsule opacification. Whether these LECs can reactivate when the capsular bend is eliminated by later formation of a Soemmerring's ring requires further studies.

Potentially Accommodating 1CU Intraocular Lens: 1-year Results in 553 Eyes and Literature Review

PURPOSE

To investigate the advantages, clinical outcomes, and safety after implantation of the 1CU (HumanOptics AG) optic shift intraocular lens (IOL) in comparison with a conventional monofocal IOL.

METHODS

In a prospective non-randomized study, 553 eyes implanted with the 1CU IOL were examined. In a control group, a monofocal posterior chamber IOL (MCTE, Dr Schmidt) was implanted in 219 eyes. Follow-up was performed at 1, 6, and 12 months postoperatively. The clinical effect for near visual acuity was evaluated by subjective measurements using an accommodometer, defocusing curve, and Nieden charts.

RESULTS

No significant differences were noted in distance best spectacle-corrected visual acuity (BSCVA) between groups. Average near visual acuity with distance BSCVA for the 1CU was 0.41 and 0.35 for the control group. The difference in the accommodation response between both groups measured with the accommodometer was 11 cm (P < .01). The refraction tolerance for the 1CU was 0.25 D whereas the MCTE revealed no refraction tolerance (P < .01). Decentration and tilting of the 1CU resulted in explantation of three IOLs.

CONCLUSIONS

The 1CU indicates a minor statistical advantage of half a reading step towards monofocal IOLs measured with subjective methods in near point, defocusing curve, and near visual acuity with distance BSCVA. This could be due to pseudophakic accommodation by the optic shift mechanism or a result of additional pseudophakic pseudoaccommodation. The accommodative effect of the 1CU differed from patient to patient and was not predictable.

Advances in anterior segment imaging

PURPOSE OF REVIEW

Imaging of the crystalline lens and intraocular lens is becoming increasingly more important to optimize the refractive outcome of cataract surgery, to detect and manage complications and to ascertain advanced intraocular lens performance. This review examines recent advances in anterior segment imaging.

RECENT FINDINGS

The main techniques used for imaging the anterior segment are slit-lamp biomicroscopy, ultrasound biomicroscopy, scheimpflug imaging, phakometry, optical coherence tomography and magnetic resonance imaging. They have principally been applied to the assessment of intraocular lens centration, tilt, position relative to the iris and movement with ciliary body contraction.

SUMMARY

Despite the advances in anterior chamber imaging technology, there is still the need for a clinical, high-resolution, true anatomical, noninvasive technique to image behind the peripheral iris.

In vivo imaging of posterior capsule opacification using Spectral Optical Coherence Tomography

Three years after uneventful extracapsular cataract extraction with implantation of a poly(methyl methacrylate) (PMMA) intraocular lens (IOL) (MZ60BD, Alcon) in a 74-year-old man, the anterior segment of the right eye was photographed with a Canon EOS 300D digital camera and examined with a slitlamp and a prototype spectral optical coherence tomography (SOCT) instrument. Subsequently, a neodymium:YAG laser posterior capsulotomy was performed, followed by another examination. The quality of the SOCT images was adequate for detailed cross-sectional evaluation of the IOL, posterior capsule opacification (PCO), and morphological changes after laser capsulotomy. En face contour maps of PCO distribution were created from 3-dimensional SOCT data. The results presented indicate future applicability of SOCT technology in evaluating modern IOL designs and investigating the process of PCO formation.

Objective measurement of intraocular lens movement and dioptric change with a focus shift accommodating intraocular lens

PURPOSE

To objectively measure the shift and refractive change of the 1CU accommodating intraocular lens (IOL) (HumanOptics) and compare them to that of a monofocal AcrySof MA30 IOL (Alcon Laboratories) in the fellow eye.

SETTING

Ophthalmology Department, St. Thomas' Hospital, London, United Kingdom.

METHODS

Thirty patients who had bilateral cataract surgery 18 to 24 months previously with a 1CU IOL prospectively randomly allocated to 1 eye and an AcrySof MA30 monofocal IOL to the other eye were examined. Distance correction, near vision, reading fluency, near point, and defocus to minus spheres were measured. Intraocular lens shift to an accommodative stimulus following instillation of pilocarpine 4% was measured with the ACMaster. Refractive change between distance and near was measured with the Tracey wavefront analyzer.

RESULTS

Of the original 30 patients recruited, complete measurements could only be obtained for 20. There was no significant difference in near visual function with either IOL. A small anterior movement of the 1CU was seen with accommodation 0.010 mm +/- 0.028 (SD). After pilocarpine 4% instillation, a forward movement of 0.220 +/- 0.169 mm was seen with the 1CU compared to a backward movement of 0.028 +/- 0.095 with the MA30. There was no significant correlation between distance corrected near visual acuity and IOL movement. No change in spherical equivalent between distance and near was seen on wavefront analysis of either IOL.

CONCLUSIONS

Small forward movement of the 1CU IOL was seen with accommodation and increased following pilocarpine, compared to the posterior movement of the MA30 IOL. The amount of the IOL shift was not sufficient to provide useful near vision, but the difference suggests that the engineering concept behind the 1CU IOL is valid.

Long-term changes in the morphology of posterior capsule opacification

PURPOSE

To classify the morphologic appearance of posterior capsule opacification (PCO) and to observe and document the changes over longer periods of time.

SETTING

Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

METHODS

Eighty-one pseudophakic eyes of 53 patients with PCO of varying degrees were included in this prospective study. Digital retroillumination images of the posterior capsule were taken in a standardized fashion 1, 2, and 3 years after cataract surgery. The PCO morphology was classified, and changes among the 3 follow-up images were analyzed.

RESULTS

At 1, 2, and 3 years, pearls occurred in 16 (20%), 41 (51%), and 57 (63%) eyes. Pearls increased in size and number. Cases with thin layers of PCO decreased from 53 to 33 to 16 eyes. Conversely, cases with thick layers increased from 18 to 45 and 64 eyes. "Cheese holes" appeared most frequently as the predominant structure (range 47% to 51%), followed by plates (range 28% to 31%), islands (range 15% to 20%), and traces of PCO (range 1% to 5%). Changes in expansion of the PCO area were observed in 61 eyes (75%) during period 1 (1 to 2 years) and period 2 (2 to 3 years). Regions of expansion and regression in the same eye occurred in periods 1 and 2 in 11 eyes (14%) and 9 eyes (11%), respectively. The phenomenon of thinning bridges, a regression of syncytial extensions of PCO, occurred in 22 eyes (27%) and 32 eyes (40%), respectively. An overlapping growth of 2 layers was observed in 18 eyes (22%).

CONCLUSIONS

The morphology of PCO is multifaceted. Apart from the Elschnig pearls, categories such as cheese holes, plates, islands, and traces of PCO were distinguished. Over the years, pearls increased in frequency, size, and number. Expansion and regression occurred simultaneously in some cases. Two or more layers grew on top of each other in some eyes.

Posterior capsule opacification

PURPOSE OF REVIEW

This paper assesses the factors that contribute to the formation of an effective capsular bend as a deterrent to posterior capsule opacification. Its goal is to assist the practicing ophthalmologist in separating current understanding of this process from various working models previously proposed.

RECENT FINDINGS

While a square-edge design appreciably improves resistance to posterior capsule opacification, significant factors remain under the control of the surgeon. These factors combine to form the physical and psychological barrier of a capsular bend. Innovative digital imaging has shown lens epithelial cell migration, allowing for a more rapid assessment of posterior capsule opacification resistance. A three-piece intraocular lens allows for full 360 degree capsular bend formation surrounding the optic edge; some single-piece designs may inhibit capsular bend formation. Decreasing, but not eliminating, the surviving lens epithelial cell population may diminish capsular bend strength, which may decrease resistance to posterior capsule opacification in the face of a regenerating cortex. All demographic features of clear/refractive lens exchange suggest higher rates of posterior capsule opacification than with standard cataract surgery.

SUMMARY

The quality of capsular bend formation will determine how resistant an intraocular lens will be to posterior capsule opacification as a consequence of regenerating cortex. As refractive lens exchange and new accommodating intraocular lens designs become more popular, the problems of regenerating cortex will increase in magnitude.

Influence of optic edge design, optic material, and haptic design on capsular bend configuration

PURPOSE

To assess and classify capsular bend configuration at the optic rim and its association with posterior capsule (PCO) and anterior capsule opacification (ACO) and capsulorhexis contraction with various intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

METHODS

A total of 659 post-cataract surgery eyes of 370 patients from different prospective randomized studies were evaluated. All eyes had standardized phacoemulsification surgery with implantation of an IOL in the capsular bag. The IOLs had a sharp or round optic edge design and were made of silicone, acrylic, or poly(methyl methacrylate) optic materials. One year postoperatively, the configuration of the capsular bend at the optic rim was assessed at the slitlamp, and standardized slitlamp images of ACO and fibrotic PCO were taken. One week, 1 year, and 3 years postoperatively, digital retroillumination images were taken for objective quantification of regeneratory PCO and the capsulorhexis area. The outcome measures were the type of capsular bend configuration, ACO score (0% to 100%), regeneratory PCO score (0 to 10), fibrotic PCO score (0 to 3), and amount of capsulorhexis contraction (mm(2)).

RESULTS

Four main types of capsular bend configuration were classified: parallel, "Y," right angle, and wrapping. The right-angle type was observed in the most cases (52%). Eyes with a wrapping capsular bend configuration had significantly less PCO, more capsulorhexis contraction, and more ACO than eyes with the other configurations. Wrapping capsule configuration was seen most often (55%) in round-edged silicone IOLs that had a thin optic rim.

CONCLUSION

The design and material of IOLs influenced the long-term capsular bend configuration at the optic rim. The right-angle type was the most common capsular bend configuration. Intraocular lenses with silicone optic material and a thin optic rim caused a wrapping capsule configuration and resulted in more capsulorhexis contraction and ACO, but less PCO.

[Influence of intraocular lens material and design on the development of posterior capsule opacification]

Based on the literature of 1999-2005, we attempted to clarify the influence of material and design of an intraocular lens (IOL) on the development of posterior capsule opacification (PCO) and identify the future problems to be solved. The sharp edge design of an IOL has significantly reduced PCO in recent years. Histopathological studies showed that a sharp capsular bend was formed at the sharp posterior optic edge, and the migration of lens epithelial cells was obviously inhibited at the site. Experimental and clinical studies suggest that the sharper the edge is, the sharper the capsular bend, and the greater the preventive effect, regardless of IOL material. The sharp capsule bend appears to represent a physical hindrance, which may induce contact inhibition of cell movement. How material participates in the preventive effect should be clarified in a future study. Thus, at the moment, the formation of capsular bend at the posterior optic edge appears to be the decisive criterion to evaluate the influence of IOL material and design on the development of PCO. Optimization of design and material of an IOL, which facilitates capsular bend formation as sharply and quickly as possible, may reduce PCO to a clinically negligible level.