Intraocular lens movement caused by ciliary muscle contraction

Fluctuations of Anterior Chamber Depth and Astigmatism in Pseudophakic Eyes

Purpose

To explore the significance of changes in anterior chamber depth (ΔACD) and astigmatism between 4 and 8 weeks following uneventful phacoemulsification.

Patients and Methods

Anterior chamber depth (ACD, mm), autorefractometry and subjective refraction were monitored in pseudophakic eyes implanted with non-toric IOLs (group 1, SA60AT, n=36; group 2, SN60WF, n=34; group 3, ICBOO, n=16) and phakic control group (n=30, group 4a, for ACD and autorefractometry) over four weeks. Changes in subjective refractions were compared with repeatability in normal phakic eyes (n=30, group 4b).

Results

Reporting key results (p<0.01), mean (±sd 95% CI) ΔACD values (ACD at start minus ACD at four weeks) were +0.02 (±0.37, -0.16 to 0.08), +0.22 (±0.51,0.05 to 0.39), -0.33 (±0.51, -0.58 to -0.08), -0.02 (±0.07, -0.04 to 0.01) in groups 1-4a respectively. Differences were significant (1-way ANOVA, F=7.02). Pooling data from the pseudophakic eyes (n=86) induced astigmatism (IA) by autorefractometry was significantly greater in comparison with group 4a [-0.78D (±0.67, -0.92 to -0.64) and -0.19D (±0.16, -0.25 to - 0.13)]. IA power correlated with the initial power of refractive astigmatism at 4 weeks (A), [IA = 0.36A-0.30 (r2=0.207) and IA = 0.39A-0.29 (r2=0.232) by autorefractometry and subjective refraction, respectively]. In groups 1-3, vector analysis revealed i) the change in refraction in over 55% of eyes was beyond the 95% confidence interval limits observed in groups 4a and 4b, ii) some significant associations between changes in vectors describing astigmatism with ΔACD and IOL labelled power.

Conclusion

Changes in ACD and refraction still occur four weeks after unremarkable phacoemulsification and the inter-relationship depends on IOL design/type. Other factors, such as tilt or dislocation of the IOL along the X-Y axes parallel to Listing's plane, accompanying changes in ACD are expected to affect the postop astigmatism.

Iris Morphological and Biomechanical Factors Influencing Angle Closure During Pupil Dilation

Purpose

To use finite element (FE) analysis to assess what morphologic and biomechanical factors of the iris and anterior chamber are more likely to influence angle narrowing during pupil dilation.

Methods

The study consisted of 1344 FE models comprising the cornea, sclera, lens, and iris to simulate pupil dilation. For each model, we varied the following parameters: anterior chamber depth (ACD = 2-4 mm) and anterior chamber width (ACW = 10-12 mm), iris convexity (IC = 0-0.3 mm), iris thickness (IT = 0.3-0.5 mm), stiffness (E = 4-24 kPa), and Poisson's ratio (v = 0-0.3). We evaluated the change in (△∠) and the final dilated angles (∠f) from baseline to dilation for each parameter.

Results

The final dilated angles decreased with a smaller ACD (∠f = 53.4° ± 12.3° to 21.3° ± 14.9°), smaller ACW (∠f = 48.2° ± 13.5° to 26.2° ± 18.2°), larger IT (∠f = 52.6° ± 12.3° to 24.4° ± 15.1°), larger IC (∠f = 45.0° ± 19.2° to 33.9° ± 16.5°), larger E (∠f = 40.3° ± 17.3° to 37.4° ± 19.2°), and larger v (∠f = 42.7° ± 17.7° to 34.2° ± 18.1°). The change in angles increased with larger ACD (△∠ = 9.37° ± 11.1° to 15.4° ± 9.3°), smaller ACW (△∠ = 7.4° ± 6.8° to 16.4° ± 11.5°), larger IT (△∠ = 5.3° ± 7.1° to 19.3° ± 10.2°), smaller IC (△∠ = 5.4° ± 8.2° to 19.5° ± 10.2°), larger E (△∠ = 10.9° ± 12.2° to 13.1° ± 8.8°), and larger v (△∠ = 8.1° ± 9.4° to 16.6° ± 10.4°).

Conclusions

The morphology of the iris (IT and IC) and its innate biomechanical behavior (E and v) were crucial in influencing the way the iris deformed during dilation, and angle closure was further exacerbated by decreased anterior chamber biometry (ACD and ACW).

Incidence and factors for pseudoaccommodation after monofocal lens implantation: the Monofocal Extended Range of Vision study

PURPOSE

To screen patients with a monofocal intraocular lens (IOL) for incidence of unaided 20/40 and 0.3 LogMAR for distance and near (pseudoaccommodation) and to find factors for pseudoaccommodation.

SETTINGS

University Hospitals Sussex NHS Foundation Trust, Brighton, United Kingdom.

DESIGN

Prospective study.

METHODS

This was a single-eye study ( ClinicalTrials.gov : NCT04011696). At 3 to 9 months, refraction, uncorrected and corrected distance and uncorrected near visual acuity (logMAR), spherical equivalent (SEQ), mesopic pupil size (PS), total eye spherical (Z 40 ), vertical coma (Z 3-1 ) aberrations, reading speed and smallest print size were assessed. Refractive astigmatism (RA) was classified as against-the-rule, with-the-rule, oblique and no astigmatism. Data on preoperative axial length (AL) and anterior chamber depth (ACD) were collected.

RESULTS

29 patients (9.6%, 95% CI, 6.5-13.5) had pseudoaccommodation. In cases vs controls, median SEQ, PS, total Z 40 , Z 3-1 , reading speed, smallest print size, preoperative ACD, preoperative AL were: -0.39 vs 0.0 diopters; 3.62 vs 4.10 mm; 0.01 vs 0.02 μm; 0.018 vs 0.022 μm; 106 vs 133 words per minute; 0.30 vs 0.50 logMAR; 2.94 vs 3.13 mm, 23.4 vs 23.7 mm, respectively. RA was not different between the groups. Univariate analysis revealed preoperative ACD (odds ratio [OR], 0.38, 95% CI, 0.16-0.94, P = .04), SEQ (OR, 0.61, 95% CI, 0.42-0.88, P = .01), total Z 40 (OR, 0.0003, 95% CI, 0.00-0.39, P = .03) and PS (OR, 0.39, 95% CI, 0.22-0.69, P < .041) to be significant. Whereas multivariable logistic regression identified: preoperative AL (OR, 0.62, 95% CI, 0.42-0.91, P = .02), SEQ (OR, 0.49, 95% CI, 0.31-0.78, P = .01), Z 40 (OR, 0.00, 95% CI, 0.0-0.01, P = .01) and PS (OR, 0.41, 95% CI, 0.23-0.75, P = .01) to be significant.

CONCLUSIONS

A combination of low myopic SEQ, lower Z 40 , shorter preoperative AL, and smaller PS increases the chances of pseudoaccommodation.

Evaluation of a Novel Zonular Tension Restoring Accommodating Silicone IOL Design: Pilocarpine and Cyclopentolate-Induced Effect 20 Months after Implantation

Purpose

To investigate a novel zonular-stress restoring accommodating 1-piece silicone IOL. Setting. Angeles City, Philippines.

Design

Prospective randomized bilateral study.

Methods

Each patient received a study IOL (ActaLens™, Emmetrope, La Canada, CA) in one eye and a control IOL (CrystaLens® AO, B&L, USA, or an AcrySof IQ®, Alcon, USA) in the contralateral eye to allow for intraindividual comparison. At the 20-month follow-up, two measurement days were set to measure all eyes before and after instilling 2% pilocarpine on the first day and 1% cyclopentolate on the second measurement day using an optical biometry device (Lenstar, Haag-Streit AG, Switzerland), respectively. PCO was graded by two examiners independently at the slit lamp.

Results

In total, 16 eyes of 8 patients were included. In the study group and the control group, the pilocarpine-induced ACD shift was 0.32 mm (SD: 0.12) (p=0.014) and 0.04 mm (SD: 0.16) (p=0.854), respectively. In the study group and the control group, the mean cyclopentolate-induced ACD shift was 0.14 (SD: 0.06) (p=0.014) and 0.03 mm (SD: 0.03) (p=0.181), respectively. PCO and Nd : YAG rates were higher in the study group, but differences were not found to be significant (AcrySof vs. ActaLens p=0.100 and CrystaLens vs. ActaLens p=0.174).

Conclusion

The investigated IOL is a novel concept for an accommodating IOL, and results showed a moderate pilocarpine-induced forward shift of the IOL 20 months following implantation. For all patients, the investigated IOL seems to have a higher PCO rate compared to standard monofocal IOLs.

Machine learning adaptation of intraocular lens power calculation for a patient group

Background

To examine the effectiveness of the use of machine learning for adapting an intraocular lens (IOL) power calculation for a patient group.

Methods

In this retrospective study, the clinical records of 1,611 eyes of 1,169 Japanese patients who received a single model of monofocal IOL (SN60WF, Alcon) at Miyata Eye Hospital were reviewed and analyzed. Using biometric metrics and postoperative refractions of 1211 eyes of 769 patients, constants of the SRK/T and Haigis formulas were optimized. The SRK/T formula was adapted using a support vector regressor. Prediction errors in the use of adapted formulas as well as the SRK/T, Haigis, Hill-RBF and Barrett Universal II formulas were evaluated with data from 395 eyes of 395 distinct patients. Mean prediction errors, median absolute errors, and percentages of eyes within ± 0.25 D, ± 0.50 D, and ± 1.00 D, and over + 0.50 D of errors were compared among formulas.

Results

The mean prediction errors in the use of the SRT/K and adapted formulas were smaller than the use of other formulas (P < 0.001). In the absolute errors, the Hill-RBF and adapted methods were better than others. The performance of the Barrett Universal II was not better than the others for the patient group. There were the least eyes with hyperopic refractive errors (16.5%) in the use of the adapted formula.

Conclusions

Adapting IOL power calculations using machine learning technology with data from a particular patient group was effective and promising.

Agreement and variability of subjective refraction, autorefraction, and wavefront aberrometry in pseudophakic patients

PURPOSE

To evaluate the comparability and variability of subjective refraction (SR), autorefraction (AR), and wavefront aberrometry (WA) in pseudophakic patients.

SETTING

Hanusch Hospital, Vienna, Austria.

DESIGN

Prospective study.

METHODS

Subjective refraction was performed by 2 independent examiners at 2 study visits. Furthermore, 5 measurements of AR and WA were performed in each patient at both visits. Agreement between the 3 refraction methods for spherical equivalent (M) and cylindrical vectors (J0, J45) was analyzed using Friedman multiple comparison and Bland-Altman plots. Predictability of spherical equivalent determined by SR from AR and WA measurements was tested with partial least squares regression and random forest regression.

RESULTS

Ninety eyes of 90 pseudophakic patients were measured. The mean absolute error and arithmetic mean difference of SR measurements of M, J0, and J45 were comparable between both examiners. A small mean difference was found for SR between both visits. Spherical equivalent was more negative when measured by AR [-0.87 diopters (D)] and WA (-0.90 D) compared with SR (-0.60 D), whereas astigmatic vectors agreed well. Good test-retest reliability was found between all 3 refraction methods for M, J0, and J45. Partial least squares regression and random forest regression showed moderate predictive power for M measured by objective refraction and SR.

CONCLUSIONS

Reproducibility and reliability of SR measurements in pseudophakic patients showed good agreement. AR and WA measured the spherical equivalent more myopic than SR, whereas astigmatic vectors were comparable between the 3 methods after uneventful cataract surgery.

Effects of Miosis on Anterior Chamber Structure in Glaucoma Implant Surgery

We investigated changes in anterior chamber (AC) structure after miosis in phakic eyes and pseudophakic eyes with glaucoma. In this prospective study, patients scheduled for glaucoma implant surgery were examined using anterior segment optical coherence tomography before and after miosis. Four AC parameters (AC angle, peripheral anterior chamber (PAC) depth, central anterior chamber (CAC) depth, and AC area) were analyzed before and after miosis, and then compared between phakic and pseudophakic eyes. Twenty-nine phakic eyes and 36 pseudophakic eyes were enrolled. The AC angle widened after miosis in both the phakia and pseudophakia groups (p = 0.019 and p < 0.001, respectively). In the phakia group, CAC depth (p < 0.001) and AC area (p = 0.02) were significantly reduced after miosis, and the reductions in PAC depth, CAC depth, and AC area were significantly greater than in the pseudophakia group (all p < 0.05). Twenty-five patients (86.2%) in the phakia group and 17 (47.2%) in the pseudophakia group had reduced CAC depth (p = 0.004). Although miosis increased the AC angle in both groups, AC depth decreased in most phakic eyes and a substantial number of pseudophakic eyes. Preoperative miosis before glaucoma implant surgery may interfere with implant tube placement distant from the cornea during insertion into the AC.

Pupil Function in Pseudophakia: Proximal Miosis Behavior and Optical Influence

The pseudophakic eye lacks the ability to produce a refractive change in response to object proximity. Thus, individual anatomical features such as the pupil size play an important role in achieving functional vision levels. In this work, the range of pupil sizes at varying object distance was measured in pseudophakic participants. Furthermore, the impact of the measured values on eye optical quality was investigated using a computer simulation model. A binocular eye-tracker was used to measure the participants’ pupil sizes at six object distances, ranging from 0.33 m (i.e., vergence of 3.00 D) to 3.00 m (i.e., vergence of 0.33 D), while observing a Maltese cross with a constant angular size of 1 ∘ . In total, 58 pseudophakic participants were enrolled in this study (age mean ± standard deviation: 70.5 ± 11.3 years). The effects of object distance and age on pupil size variation were investigated using linear mixed effects regression models. Age was found to have a small contribution to individual variability. The mean infinite distance pupil size (intercept) was 4.45 ( 95 % CI: 2.74, 6.17) mm and the mean proximal miosis (slope) was − 0.23 ( 95 % CI: −0.53, 0.08) mm/D. The visual acuity (VA) estimation for a distant object ranged from − 0.1 logMAR (smallest pupil) to 0.04 logMAR (largest pupil) and the near VA ( 0.33 m) when mean proximal miosis was considered ranged from 0.28 logMAR (smallest pupil) to 0.42 logMAR (largest pupil). When mean distance pupil was considered, proximal miosis individual variability produced a variation of 0.04 logMAR for the near object and negligible variation for the distant object. These results support the importance of distance pupil size measurement for the prediction of visual performance in pseudophakia, while suggesting that proximal miosis has a negligible impact in VA variability.

Ambient fine particulate matter and ozone higher than certain thresholds associated with myopia in the elderly aged 50 years and above

Although myopia has been largely ignored among the elderly population, there is an increased risk of myopia with advancing age. Ambient air pollution is one potential contributor to vision impairments, but few epidemiological studies have demonstrated such an association. This cross-sectional survey collected the information of 33,626 subjects aged ≥50 years in six developing countries during 2007-2010. Myopia was identified based on questions related to symptoms of myopia. The annual concentrations of fine particulate matter (PM_2.5) and ozone (O₃) were estimated with the satellite data and chemical transport model. We examined the associations between the two pollutants and myopia using mixed-effect Poisson regression models with robust variance estimation (sandwich estimation). We observed J-shaped associations between the two pollutants and myopia, and identified 12 and 54 μg/m³ as the threshold concentrations. The adjusted prevalence ratio was 1.12 (95% CI: 1.05, 1.21) and 1.26 (95% CI: 1.14, 1.38) for each standard deviation (SD) increase in PM_2.5 and O₃ concentrations above their threshold, respectively. In addition, the interaction analysis suggested a synergistic interaction of these two pollutants on myopia in the additive model, with a synergistic index of 1.81 (Bootstrapping 95% CI: 0.92, 4.94). Our results indicate that long-term exposures to PM_2.5 and O₃ might be important environmental risk factors of myopia in the elderly, and suggest that more efforts should be taken to reduce airborne PM_2.5 and O₃ levels to protect vision health.

[Presbyopia and refractive surgery]

Presbyopia is the progressive loss of accommodation. Accommodation is a quick, precise and involuntary action which enables the eye to change the power of the young crystalline lens to see clearly at all distances. Presbyopia is and age-linked physiologic phenomenon: it results from aging of the lens, which loses its elasticity, gradually becomes rigid and loses the ability to accommodate. Presbyopia has attained a prevalence of 80% in Europe and is increasing regularly due to the aging of the population. Various surgical techniques can be proposed. Indications depend on age, ophthalmological exam, and any associated ametropia. The main techniques act by either changing the curvature of the cornea with laser or with an intrastromal inlay to create pseudoaccomodation, or by intraocular lens surgery with a multifocal or accommodating IOL. Once the surgical choice has been made, the information must be clearly conveyed and consent obtained.

Clinical application of accommodating intraocular lens

The present review describes recent advances in application of accommodating intraocular lenses (AIOLs). Standard monofocal intraocular lenses (MIOLs) only correct distance vision, while AIOLs are designed to allow both good distance vision and near vision, which is achieved through the contraction and relaxation of ciliary muscles by providing transformation of the axial movement or curvature of the lens. Thus, AIOLs may be a better choice for those patients who demand a higher level of visual performance. Since techniques to analyze the performance of AIOLs have not been standardized, and there is a variety of both subjective and objective methods, it is hard to measure the performance of these intraocular lenses. By evaluating advantages and disadvantages of various AIOLs, and introducing techniques for measurement the performance postoperative, this paper can provide some relative information on choosing the type of AIOLs in the clinic.

Accommodative Intraocular Lenses: Short-Term Visual Results of Two Different Lens Types

Purpose

To compare the ability of two types of accommodative intraocular lenses (IOLs) to provide uncorrected near and distance visual acuity (VA) after cataract surgery.

Methods

A total of 108 eyes of 75 patients underwent cataract surgery by phacoemulsification and IOL implantation either bilaterally or monocularly with one of two types of accommodative IOLs: the AT-45 lens (69 eyes) or the 1-CU lens (39 eyes). Patients were followed for up to 1 year after cataract surgery. Near VA was measured through the distance correction to obtain the true near vision effect of the accommodating IOL.

Results

Uncorrected distance VA of 20/30 or better was achieved by 84.6% of the bilaterally implanted 1-CU patients and 73.6% of the bilaterally implanted AT-45 IOL patients 1 year following surgery. Uncorrected near VA of J1 or better was achieved by 42% of the patients with the bilateral 1-CU implant and 36.8% of the patients with the bilateral AT-45 implant. For J3 or better near acuity, the values were 92.3% for the bilateral 1-CU patients and 84.2% for the bilateral AT-45 patients at 1 year. A total of 54% of the eyes with 1-CU implants underwent a mild myopic shift (<1.0 D), 21% had a mild hyperopic shift, and 45% of the eyes were emmetropic at 1 year.

Conclusions

Both accommodative IOLs provided good near and distance vision postoperatively. The 1-CU IOL appears clinically to provide slightly better uncorrected distance and distance-corrected near VA than the AT-45 lens.

Short-term fluctuation of lens corneal distance and clinical correlation with phacodonesis

BACKGROUND

To analyze the role of short-term lens-corneal distance (LCD) fluctuation in quantifying preoperative phacodonesis and predicting intraoperative zonular weakness.

METHODS

Patients were divided into control (lens without clinical phacodonesis) and study (lens with suspicious and clinical phacodonesis) groups for evaluation. Slit-lamp examination followed by IOLMaster (Carl Zeiss) for LCD assessment was performed. Five readings were taken at five time points (0 s, 15 s, 30 s, 45 s & 60 s) continuously over a minute (short term) for the LCD fluctuation calculation.

RESULTS

A total of 135 eyes (82 controls and 53 study) were assessed. Study group included 32 (60.3%) suspicious and 21 (39.6%) moderate to severe phacodonesis. There was difference between the control and study eyes (p = 0.000) in short-term LCD fluctuation. Twenty-one study eyes (39.6%) showed LCD difference > 1 mm, including 11 eyes (52.3%) with > 2 mm. There was a difference in LCD with respect to severity of phacodonesis (p = 0.000). In the study eyes, 13 eyes underwent glued IOL implantation (clinical phacodonesis - ten, suspicious phacodonesis - three), and two eyes (suspicious phacodonesis) had glued capsular hook. Thirteen eyes (clinical phacodonesis - ten, suspicious phacodonesis - three) required intraoperative vitrectomy due to vitreous ingress. Intraoperative zonular weakness in 62.5% of eyes with suspicious donesis and association (Chi-square = 0.000) of weakness with preoperative LCD fluctuation was noted.

CONCLUSIONS

Short-term lens-corneal distance fluctuation can be used as a parameter for quantifying lens stability and as an aid in assessing the intraoperative risk.

Pathology and immunohistochemistry of capsular bag in spontaneously late dislocated capsular bag-intraocular lens complex

Purpose:

Our study aims to evaluate the morphology, histopathology, and immunohistochemistry of the spontaneously late dislocated capsular bag-intraocular lens (CB-IOL) complex. Various etiologies and possible pathogenesis of the event are also discussed.

Methods:

This was a tertiary-care setting and retrospective observational case series. The surgically explanted intact specimens of spontaneously late dislocated CB-IOL complex were studied. The demographics, duration of pseudophakia, IOL design/material, and specimen measurements were noted. Fresh specimens were photographed, and computer software was used for measurements. After processing, a detailed microscopic examination was carried out for three different sections of each specimen with hematoxylin and eosin (H and E), Masson's-trichrome, and immunohistochemistry stain for vimentin. The Mann–Whitney U-test was used for the statistical analysis.

Results:

Of 12 specimens, the mean CB and capsulorhexis opening size were 8.32 ± 0.8 mm and 3.62 ± 0.61 mm, respectively. The average CB-IOL complex size of our study was significantly lower than the studies reported in the literature (P ≤ 0.001). All (n = 12, 100%) were acrylic IOLs with 11 (91.67%) having single-piece design. All specimens on H and E stain showed extensive subepithelial fibrosis while Masson's trichrome staining showed that none had any pseudoexfoliation material. The circumferential sphincter-like fibrous tissue arrangement was seen in all specimens. Immunohistochemical expression of vimentin suggested the mesenchymal metaplasia of epithelial A-cells.

Conclusion:

Significant fibrotic contraction of the CB and phimosis of capsulorhexis may cause a progressive zonular tear. This is probably the most important etiology of spontaneous late dislocation of the CB-IOL complex.

Anterior Segment Biometry of the Accommodating Intraocular Lens and its Relationship With the Amplitude of Accommodation

OBJECTIVES

To evaluate the anterior segment biometry of the Tetraflex accommodating intraocular lens (AIOL) and the contribution of forward movement to the amplitude of accommodation (AMP).

METHODS

Patients who underwent phacoemulsification with implantation of Tetraflex AIOLs and control nonaccommodating intraocular lenses were imaged by custom-built, long scan depth spectral-domain optical coherence tomography at relaxed and maximal accommodative states. Anterior segment biometry was performed and correlated with the clinical manifestation including AMP.

RESULTS

Patients in the Tetraflex group showed better distance-corrected near visual acuity (logMAR 0.43±0.10 vs. logMAR 0.51±0.10, P<0.05) and greater AMP (1.99±0.58 diopters [D] vs. 1.59±0.45 D, P<0.05) compared with the control group. The measurement of the postoperative anterior chamber depth (ACD) during accommodation showed a forward movement of the AIOLs in 16 eyes (69.6%). Compared with the control group, a greater proportion of cases in the Tetraflex group experienced forward movement (χ test, P<0.001). The AMP in the AIOL group negatively correlated with changes in postoperative ACD during accommodation (r=-0.47, P<0.05), whereas AMP in the control group negatively correlated with postoperative pupil diameter (r=-0.57, P<0.05).

CONCLUSIONS

The Tetraflex AIOLs seemed to have a tendency for forward movement; however, the slight forward axial shifts of the Tetraflex AIOL during natural accommodation may not produce a clinically relevant change in optical power.

Severe symptoms of short tear break-up time dry eye are associated with accommodative microfluctuations

AIM

Validating the hypothesis that accommodative microfluctuations (AMFs) may be associated with severe symptoms in short tear break-up time (BUT) dry eye (DE).

METHODS

This study included 12 subjects with short BUT DE (age: 49.6±18.3 years). Diagnoses were performed based on the presence of DE symptoms, BUT ≤5 s, Schirmer score >5 mm, and negative keratoconjunctival epithelial damage. Tear evaluation, AMF, and functional visual acuity (VA) examinations were conducted before and after DE treatment. The AMF parameters evaluated were: total high-frequency component (HFC), HFC with low accommodation for the task of staring into the distance (HFC1), HFC with high accommodation for deskwork (HFC2). A subjective questionnaire of DE symptoms was also performed.

RESULTS

Mean BUT increased from 1.9±2.0 to 6.4±2.5 s after treatment (P<0.05). The mean logarithm of the minimum angle of resolution functional VA significantly improved (from 0.19±0.19 to 0.12±0.17; P<0.05). Mean power spectrum values for total HFC and HFC1 decreased (from 61.3±5.7 to 53.8±6.6 dB and from 62.9±10.5 to 52.4±6.2 dB, respectively; P<0.05), while the mean HFC2 power spectrum values did not differ before and after treatment (P>0.05). Subjective DE symptoms were reduced in nine patients.

CONCLUSION

Along with the improvement of BUT after treatment, DE symptoms diminished and HFC1 and functional VA improved, suggesting that tear film instability is associated with deterioration of functional VA, AMF, and DE symptoms.

Posterior Vault Distance of Ciliary Sulcus-Implanted Three-piece Intraocular Lenses According to Ciliary Sulcus Diameter

PURPOSE

To investigate the correlation among preoperative biometry data, postoperative ciliary sulcus diameter, posterior vault distance, and effective lens position of ciliary sulcus-implanted intraocular lenses (IOLs).

DESIGN

Retrospective interventional case series.

METHODS

Twenty-six eyes of 26 patients underwent phacoemulsification with implantation of a ZA9003 IOL (Abbott Medical Optics Inc, Santa Ana, California, USA) in the ciliary sulcus. We analyzed correlations among preoperative biometry data and ultrasound biomicroscopy measurements, ciliary sulcus diameter, posterior vault distance, and effective lens position. Regression analyses were performed to identify which combination of preoperative biometry data, average corneal power (keratometry [K]), anterior chamber depth (ACD), and axial length (AL) was best for predicting effective lens position.

RESULTS

The sulcus diameter was shorter in eyes that had a steep cornea and shorter AL. The posterior vault distance was negatively correlated with sulcus diameter in subjects who had shorter postoperative time intervals (≤24 months) (R² = 0.336 and P = .038). The posterior vault distance decreased with each passing postoperative month (R² = 0.158 and P = .045). The R² value for predicting the effective lens positions of sulcus-implanted IOLs based on the entire average K, ACD, and AL was higher than those based on parts of these values.

CONCLUSIONS

The effective lens position of sulcus-implanted IOLs can be affected by sulcus diameter, and lens position can change, especially in the early postoperative period. We recommend using the entire average K, ACD, and AL to predict the effective position of sulcus-implanted IOLs.

Pseudo-accommodation in non-amblyopic children after bilateral cataract surgery and implantation with a monofocal intraocular lens: prevalence and possible mechanisms

BACKGROUND

Some pseudophakic patients implanted with a monofocal intraocular lens (IOL) have good near visual acuity (VA) with their distance correction. The objective was to evaluate the prevalence of pseudo-accommodation in children after bilateral cataract surgery, without amblyopia, and to define its mechanisms.

METHODS

Observational study that took place in a pediatric ophthalmology department, Paris, France. A total of 68 eyes were included, 40 from 23 children and 28 from 14 adults, with a corrected distance VA above 20/25 and a normal near VA (20/25) with +3 addition. Pseudo-accommodation was defined as a near VA better than 20/50 with the distance correction and without addition. Prevalence of pseudo-accommodation was calculated in each group. In order to determine the possible mechanisms of pseudo-accommodation in children, we compared children with pseudo-accommodation and adults without pseudo-accommodation regarding several parameters: refraction, axial length, corneal topography, aberrometry, pupillary diameter and IOL shift after cyclopentolate instillation.

RESULTS

Among the children group, 36 (90 %) had pseudo-accommodation versus 2 (7 %) in the adult group. We found that spherical equivalent, implant power, corneal multifocality and corneal higher-order aberrations (mainly coma and trefoil) were significantly higher in the pseudo-accommodation group, while pupil diameter and implant shift were not significantly different.

CONCLUSIONS

Pseudo-accommodation has a high prevalence among non-amblyopic pseudophakic children. Several possible mechanisms have been found to explain pseudo-accommodation in children: a high power of the IOL and a small axial length, maximizing the effect of the IOL shift, corneal multifocality and corneal higher-order aberrations.

Comparability of anterior chamber depth measurements with partial coherence interferometry and optical low-coherence reflectometry in pseudophakic eyes

PURPOSE

To assess whether anterior chamber depth (ACD) measurements in pseudophakic eyes obtained with partial coherence interferometry (PCI) and optical low-coherence reflectometry (OLCR) devices can be used interchangeably.

SETTING

Vienna Institute for Research in Ocular Surgery, A Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria.

DESIGN

Prospective case series.

METHODS

The ACD measurements in 1 eye of each pseudophakic patient were performed with the PCI-based ACMaster device and the OLCR-based Lenstar LS900 device at least 1 day postoperatively.

RESULTS

The study comprised 65 eyes of 65 patients with a mean age of 71.7 years ± 9.0 (SD) (range 39 to 91 years). In 15 eyes, no valid ACD readings could be obtained with the OLCR device. No obvious reason for these measurement failures was identified; however, tear-film alterations shortly after surgery were suspected. No significant difference in the mean ACD in the remaining 50 eyes was found between PCI measurements (5019 ± 660 μm; range 4008 to 6181 μm) and OLCR measurements (5015 ± 663 μm; range 4017 to 6163 μm) (P = .06). Three (6%) of 50 measurements were not within the 95% limits of agreement in the Bland-Altman analysis.

CONCLUSIONS

Pseudophakic ACD measurements with the PCI and OLCR devices can be used interchangeably. The OLCR device proved to be more user-friendly and faster; however, in a substantial number of eyes, no usable values were obtainable.

FINANCIAL DISCLOSURE

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

The effect of Nd:YAG laser treatment of posterior capsule opacification on anterior chamber depth and refraction in pseudophakic eyes

Purpose

This was a prospective descriptive study to determine the changes in intraocular lens (IOL) position after neodymium-doped yttrium–aluminum–garnet (Nd:YAG) laser posterior capsulotomy by measuring anterior chamber depth (ACD) and refraction, including the spherical equivalent (SE) and cylinder.

Materials and methods

Forty-seven pseudophakic eyes with posterior capsule opacification of 29 patients were included. Nd:YAG laser posterior capsulotomy was performed. Patients’ ACD and refraction were measured before the treatment, as well as after the treatment at 1 week and 3 months. IOLMaster^® and an automated refractometer were used at the Department of Ophthalmology, King Chulalongkorn Memorial Hospital, Bangkok, Thailand.

Results

There were no statistically significant differences in ACD and SE before and after laser treatment at 1 week and 3 months (repeated analysis of variance, P=0.582 and P=0.269, respectively). Both backward IOL movement (number [n]=29) and forward IOL movement (n=18) were found. Some changes in cylindrical refraction were found at 1 week, but decreased at 3 months after capsulotomy (baseline cylinder: −1.16; cylinder at 1 week and 3 months: −1.00 and −1.14, respectively; P=0.012). These changes were the same with one-piece and three-piece IOLs.

Conclusion

Nd:YAG laser posterior capsulotomy did not significantly change ACD and SE. It led to cylinder change at 1 week after laser, but the effect decreased at 3 months. This effect was small and may not be clinically significant.

Developments in the correction of presbyopia II: surgical approaches

PURPOSE

To discuss the various static and dynamic surgical approaches which attempt to give presbyopes good vision at far, intermediate and near viewing distances.

CONTENT

Static methods broadly adopt the same optical techniques as those used in presbyopic contact lens correction and aim to satisfy the needs of the presbyope by increasing binocular depth-of-focus, often using monovision as well as simultaneous-imagery. Dynamic methods generally attempt to make use of at least some of the still-active elements of the accommodation system. They include procedures which are supposed to modify the relative geometry of the ciliary muscle and lens, or which reduce the stiffness of the presbyopic lens either by replacing it with other natural or man-made material or by subjecting it to femtosecond laser treatment. Alternatively the natural lens may be replaced by some form of intraocular lens which changes power as a result of forces derived from the still-active ciliary muscle, zonule and capsule, or other sources.

CONCLUSIONS

At present, multifocal intraocular lenses appear to offer the most consistent and reliable surgical approach to surgical presbyopic correction. They have obvious advantages in convenience and stability over optically-similar, simultaneous-image presbyopic contact lenses but this must be balanced against their relative inflexibility in cases of patient dissatisfaction. Dynamic methods remain largely experimental. Although some approaches show promise, as yet no method has demonstrated a reliable, long-term ability to correct distance refractive error and to appropriately change ocular power in response to changes in viewing distance over the normal range of interest.

Association of eNOS polymorphisms with anterior chamber depth in han chinese: jiangsu eye study

Recently, a study reported that single nucleotide polymorphisms (SNP) in endothelial nitric oxide synthase (eNOS) were associated with primary angle closure glaucoma (PACG) in Australian cohort. In this study, we aimed to investigate whether those eNOS SNPs are associated with primary angle closure (PAC) or ocular biometric characteristics such as axial length (AL), anterior chamber depth (ACD), and diopter of spherical power (DS) in Han Chinese. The samples consisted of 232 PAC subjects and 306 controls collected from a population-based prevalence survey conducted in Funing County of Jiangsu, China. The rs3793342 and rs11771443 in eNOS were genotyped by TaqMan-MGB probe using the RT-PCR system. Our data did not identify any association of the eNOS SNPs with PAC. However, the analysis on the quantitative traits of ocular biometrics showed that the ACD of rs11771443 AA and GA carriers is significantly deeper than that of rs11771443 GG carriers (P = 0.0025), even though the AL and DS are not associated with rs11771443 genotypes. Rs3793342 was not associated with any biometric parameters including ACD, AL and DS. In summary, our data indicates that eNOS rs11771443 is associated with ACD and its role in the pathogenesis of PACG warranted further study.

Effect of primary posterior continuous curvilinear capsulorrhexis with posterior optic buttonholing on pilocarpine-induced IOL shift

PURPOSE

To assess intraocular lens (IOL) shift along the visual axis induced by ciliary muscle contraction with pilocarpine after cataract surgery and to compare primary posterior continuous curvilinear capsulorrhexis (CCC) and posterior optic buttonholing with IOLs implanted in the bag.

SETTING

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

DESIGN

Clinical trial.

METHODS

Eyes with age-related cataract had cataract surgery with implantation of a nonaccommodating IOL (AF-1 YA-60BB). Surgery was performed with primary posterior CCC and posterior buttonholing in 1 eye (study eyes) and with conventional in-the-bag implantation in the contralateral eye (control eyes). After a minimum of 6 months postoperatively, the anterior chamber depth was assessed with partial coherence interferometry before and after application of pilocarpine 2.0% and, after a washout interval of 1 week, before and after the application of cyclopentolate 1.0%.

RESULTS

Forty eyes of 20 patients were enrolled. A slight backward shift of the IOL (+78 μm) in study eyes and in control eyes (+118 μm) was detected after pilocarpine application (both P<.05). No significant difference in IOL shift was found between study eyes and control eyes (P=.19).

CONCLUSIONS

Combined primary posterior CCC and posterior optic buttonholing did not affect IOL shift during pharmacologically stimulated ciliary muscle contraction compared with in-the-bag implanted IOLs. Capsule fibrosis diminished with primary posterior CCC but did not seem to be the only limiting factor in the accommodative IOL shift.

FINANCIAL DISCLOSURE

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

Real and pseudoaccommodation in accommodative lenses

In the attempt to manage presbyopia, different intraocular lens designs have been proposed such as monofocal IOLs with monovision or multifocal IOLs. Even though the lenses mentioned offer satisfactory visual results, contemporary ophthalmology has not completely answered the presbyopic dilemma by simulating the accommodative properties of the crystalline lens itself. Accommodative IOLs were designed to fill this gap and provide satisfactory vision for all distances by restoring some degree of "pseudoaccommodation." Pseudo accommodative capability can be linked to monofocal IOL's as well but the results are not satisfactory enough to fully support unaided near vision. Pseudoaccommodation is a complex phenomenon that can be attributed to several static (i.e., pupil size, against-the-rule cylindrical refractive error, multifocality of the cornea) and dynamic (i.e., anterior movement of the implant itself) factors. Objective measurement of the accommodative capability offered by the accommodative IOLs is extremely difficult to obtain, and different methods such as autorefractometers, retinoscopy, and ultrasound imaging during accommodative effort, ray tracing, or pharmacological stimulation have been developed but the results are sometimes inconsistent. Despite the difficulties in measuring accommodation, accommodative IOLs represent the future in the attempt to successfully "cure" presbyopia.

Strehl ratios characterizing optical elements designed for presbyopia compensation

We present results of numerical analysis of the Strehl ratio characteristics for the light sword optical element (LSOE). For comparison there were analyzed other optical imaging elements proposed for compensation of presbyopia such as the bifocal lens, the trifocal lens, the stenopeic contact lens, and elements with extended depth of focus (EDOF), such as the logarithmic and quartic axicons. The simulations were based on a human eye's model being a simplified version of the Gullstrand model. The results obtained allow to state that the LSOE exhibits much more uniform characteristics of the Strehl ratio comparing with other known hitherto elements and therefore it could be a promising aid to compensate for the insufficient accommodation range of the human eye.

A randomized intraindividual comparison of the accommodative performance of the bag-in-the-lens intraocular lens in presbyopic eyes

PURPOSE

To compare the accommodative performance of the Morcher BioComFold Type 89A bag-in-the-lens intraocular lens (IOL) with a conventional in-the-bag control IOL in presbyopic eyes.

DESIGN

Prospective, randomized clinical trial with intraindividual comparison.

METHODS

SETTING

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

STUDY POPULATION

Fifty-two eyes of 26 patients with bilateral age-related cataracts.

INTERVENTION

Phacoemulsification cataract extraction with implantation of a bag-in-the-Lens and a control IOL, the Alcon AcrySof SA60AT (Alcon Laboratories, Fort Worth, Texas, USA), randomized to either eye.

MAIN OUTCOME MEASURES

Axial IOL shift stimulated by physiologic (near visual effort) and pharmacologic (pilocarpine and cyclopentolate) accommodative stimulation was measured objectively with partial coherence interferometry. Other outcome measures were objective and subjective accommodation, logarithm of the minimal angle of resolution distance-corrected near visual acuity, and defocus curves.

RESULTS

Three months after surgery, axial IOL shift stimulated by near visual effort measured -5.9 ± 10.3 μm in bag-in-the-lens eyes versus -8.4 ± 12.8 μm in control eyes (P = .37), that stimulated by pilocarpine measured 20.2 ± 165.6 μm versus 50.4 ± 164.4 μm (P = .36), and that stimulated by cyclopentolate measured -65.8 ± 64.3 μm versus -54.0 ± 37.5 μm (P = .34), respectively (n = 25). Objective accommodation measured 0.03 ± 0.18 diopters (D) in bag-in-the-lens eyes versus 0.08 ± 0.21 D in control eyes (P = .40), whereas subjective accommodation measured 2.48 ± 0.72 D versus 2.45 ± 0.80 D (P = .75), respectively. Distance-corrected near visual acuity and defocus curves showed no difference between IOLs.

CONCLUSIONS

The bag-in-the-lens IOL demonstrated negligible axial shift and objective accommodation with physiologic near visual stimulation. The IOL shift demonstrated with pilocarpine also was clinically insignificant. The bag-in-the-lens IOL showed no accommodative or near visual advantage over a conventional in-the-bag IOL, despite its unique capsular fixation method. This provides further evidence that the focus-shift principle fails to produce clinically significant IOL movement.

Scanning system design for large scan depth anterior segment optical coherence tomography

In telecentric scanning a large lateral scan area leads to an increase in the angle of incidence on each of the four anterior ocular surfaces (two for the cornea and two for the crystalline lens), causing significant reduction in the signal obtained from regions farther from the optical axis. We propose an optical coherence tomography scanning system, which achieves nearly normal incidences across the lateral locations of the four ocular surfaces. This provides an increase in the amount of light scattered back to the system, resulting in a higher signal-to-noise ratio (SNR). The images of a model eye obtained with the proposed scan and conventional telecentric scan were compared. SNR improvement of 5dB and 12dB was observed for the anterior and the posterior lens surfaces, respectively. For the posterior corneal surface SNR improvement of 4dB was observed, while the SNR improvement for the anterior corneal surface was 0.7dB.

Evaluation of the performance of accommodating IOLs using a paraxial optics analysis

PURPOSE

We employed an analytical approach to evaluate the key parameters for the potential design optimisation of accommodating intra-ocular lenses (AIOL) and to use these parameters to predict their accommodative performance.

METHODS

Paraxial thin-lens equations to predict the accommodative performances of single-element (1E) and two-element (2E) AIOLs were developed. 2E-AIOLs with either mobile front or back lens elements were analysed as well as 1E-AIOL for their accommodative performance. A paraxial model including key ocular components (corneal surfaces, pupil and retina) as well as AIOL was used to evaluate the key control parameters and optimal design configurations. A range of variants of the model, representing varying powers of front and back optical elements and with either front or back optical element mobile was tested.

RESULTS

Optimal accommodative performance of 2E-AIOL is governed by the power combinations of its optical elements; design variants with higher positive front element power produced greater accommodative efficacy, while mobility of the front element contributed more to the accommodative performance than the back element. The performance of 1E-AIOL is primarily governed by the power of the AIOL; the higher the AIOL power, the better the accommodative performance.

CONCLUSIONS

From an accommodative performance standpoint, the optimal design of 2E-AIOL should comprise a high plus power front element. Considering the maximum potential amounts of element translation available clinically, 2E-AIOLs are predicted to offer higher accommodative performance compared to 1E-AIOL.

[Examination of accommodation in pseudophakic eyes]

Some patient with monofocal intraocular lens can achieve good near visual acuity with distance correction after cataract surgery. Understanding and measuring this phenomenon also called pseudoaccommodation can help to develop new technology to substitute or restore accommodation in pseudophakic eyes.

AIM

I. To measure accommodation after cataract surgery. II. To measure anterior chamber depth with Scheimpflug imaging and comparing results with standard, ultrasonic data. III. To compare anterior chamber depth data, repeatability, reproducibility and reliability with a new optical device, the anterior segment optical coherent tomography (Visante OCT) and immersion ultrasound method in phakic eyes.

METHODS

I. We observed accommodation with defocusing technique, partial coherent interferometry method and measuring anterior chamber depth changing during ciliary muscle blocking. II. We measured anterior chamber depth with Pentacam and data were compared to standard ultrasonic method in phakic and pseudophakic eyes. III. We analyzed anterior chamber depth data, repeatability, reproducibility and reliability obtained by two observers using Visante OCT.

RESULTS

I. A total accommodation amplitude of 0,83 D was observed with defocusing technique. Intraocular lens movement were negligible measured by partial coherent interferometry method using physiological accommodation stimulus. Mean movement of intraocular lens was 0.18 mm during blocking of the ciliary muscle. II. Pentacam and ultrasonic device measure the same anterior chamber depth in phakic eyes, but in pseudophakic eyes optical method measures significantly shallower anterior chamber depth. III. Anterior segment optical coherent tomography measures deeper anterior chamber depth than immersion ultrasonic device in phakic eyes.

CONCLUSIONS

Accomodation and pseudoaccommodation observed in pseudophakic eyes is hard to measure and only parts of this process can be measured with each technique. Anterior chamber depth data varies by the measuring technique. Repeatability, reproducibility and reliability of anterior chamber depth data were better with optical technique.

Comparison of anterior chamber depth measurements taken with the Pentacam, Orbscan IIz and IOLMaster in myopic and emmetropic eyes

PURPOSE

This study determined to assess the degree of agreement between anterior chamber depth (ACD) measurements obtained using three different devices and to analyse the relationship between ACD and spherical equivalent (SE) refraction.

METHODS

In this cross-sectional study, 42 eyes of 42 patients with a mean SE of - 4.69 +/- 4.61 D (range 0.00 D to - 14.88 D) were analysed. Measurements of ACD between the corneal epithelium and the anterior surface of the crystalline lens, obtained using the Pentacam, Orbscan IIz and IOLMaster, were compared. The relationships between SE and ACD measurements obtained with different devices were also investigated. The results were analysed using Bland-Altman analyses, single-sample t-test and Pearson's correlation test.

RESULTS

Orbscan ACD measurements were an average of 0.05 mm less than Pentacam measurements (p = 0.01). IOLMaster measurements were an average of 0.06 mm less than Orbscan measurements (p < 0.001). None of the ACD values measured by any of the devices were correlated with increasing SE (p > 0.05 for all). There was a weak positive correlation between SE and the difference in ACD measurements with Pentacam and Orbscan (p = 0.04); however, the differences between Pentacam and IOLMaster ACD measurements and Orbscan and IOLMaster ACD measurements seemed to be independent of SE (p = 0.17 and p = 0.54, respectively).

CONCLUSIONS

The ACD in clinically normal eyes is measured differently by various non-ultrasonic devices. However, the observed mean error between these modalities is too small to create any noticeable difference in refractive outcome. No significant relationship was found between SE and ACD measurements obtained by Pentacam, Orbscan or IOLMaster.

Effect of patient motivation on near vision in pseudophakic patients

PURPOSE

To investigate the effect of 'training' the patients' near vision and motivating them towards a spectacle-independent outcome on near vision performance in pseudophakic patients with standard intraocular lens (IOL).

DESIGN

Prospective randomized, controlled, examiner-masked clinical trial.

METHODS

Eighty eyes of 40 patients with standard cataract surgery were randomly assigned to a "motivated" or "control" group. In the motivated group, subjects were told that they are taking part in a special protocol to improve their near-reading ability after cataract surgery and were instructed not to use reading glasses for at least three months and received cycloplegic eye drops for 10 days after surgery. Follow-up examinations at three months included best-corrected distance visual acuity (VA), distance-corrected near VA, best-corrected near VA, assessment of the defocus curve, and reading speed, as well as pilocarpine-, cyclopentolate- and nearpoint-induced IOL shift assessed with partial coherence interferometry. Additionally, a questionnaire evaluating patients' postoperative satisfaction, independency of reading glasses, and daily-life performance without glasses was carried out three months and one year postoperatively.

RESULTS

No difference in reading ability and IOL shift between "motivated" and "control" patients could be detected. However, the motivated patients were less dependent on reading glasses and their ability to be able to perform activities of daily life without glasses was significantly better.

CONCLUSION

There was no improvement of ciliary body function in pseudophakic patients with a special training protocol. However, near vision training made patients more independent of reading glasses.

Depth of focus in pseudophakic eyes

PURPOSE

To assess depth of field/depth of focus in pseudophakic eyes as function of visual acuity.

SETTING

Department of ophthalmology of National Medical Academy of Postgraduate Education.

METHODS

Forty-three pseudophakic eyes of 43 patients after implantation in the capsular bag of monofocal posterior chamber IOLs were examined. All patients had visual acuities at least 20/20 for distance. Visual acuity was examined by charts consisting the Landolt's rings under defined constant illumination within distance from 3 m to 20 cm from patients' eyes at various distances with difference of 10 cm (29 measurements). Depth of field was calculated in diopters.

RESULTS

The mean value of the depth of field in pseudophakic eyes with pupil diameter of 3 +/- 0.3 mm was as follows: 1.12 D for visual acuity 20/20, 0.62 D for visual acuity 20/13, and 0.47 D for visual acuity 20/10.

CONCLUSIONS

Depth of focus correlates to normal levels of visual acuity. The higher the visual acuity, the lower the depth of focus. The ability of clear vision due to depth of focus-pseudoaccommodation is passive function. Separating the pseudoaccommodation from artificial accommodation in eyes with accommodative IOLs requires strict standardization of methodology especially regarding diameter of pupil, size of test objects, and level of illumination.

Lens thickness with age and accommodation by optical coherence tomography

PURPOSE

To utilize time-domain optical coherence tomography (OCT) to measure changes in the crystalline lens with age and accommodation.

METHODS

A cross-sectional study of pre-presbyopic and presbyopic subjects was conducted. Amplitude of accommodation was measured with the push-up test. Objective accommodation was measured with the Grand Seiko auto-refractor and a Badal lens system. Lens thickness was measured with the Zeiss Visante OCT and an internal optometer. The data were analysed using correlation coefficients, linear regression, and by calculating the average change in lens thickness per diopter change in objective accommodation.

RESULTS

Twenty-two subjects between the ages of 36 and 50 years completed the study. Subjective amplitude of accommodation ranged from 2.17 to 6.38 D. Objective accommodation ranged from 0.22 to 4.56 D. The mean lens thickness was 4.05+/-0.20 mm. The mean change in lens thickness for up to a 5-D accommodative stimulus ranged from 0.01 to 0.26 mm. The correlation coefficients were: age and subjective accommodation, r= -0.74; age and objective accommodation, r= -0.84; change in lens thickness and age, r= -0.65; change in lens thickness and subjective accommodation, r=0.74; change in lens thickness and objective accommodation, r=0.64; objective and subjective accommodation, r=0.82 (all p<0.01). An increase in lens thickness of 21 microm per year of age was determined by linear regression. For the subjects who showed at least 1 D of accommodative response on the Grand Seiko auto-refractor, there was an increase of 51+/-19 microm per dioptre of accommodation.

CONCLUSIONS

Optical coherence tomography is a non-invasive technique that can be used to quantify changes in the thickness of the crystalline lens. Subjective and objective measurements of accommodation, as well as age, were robustly correlated with the measured changes in lens thickness. Lens thickness changes with age and accommodation as measured with the Visante OCT compare well with previous findings using Scheimpflug photography and ultrasound.

Functional Assessment of Two Different Accommodative Intraocular Lenses Compared with a Monofocal Intraocular Lens

PURPOSE

To evaluate selected functional and physical properties of 2 models of accommodative intraocular lenses (IOLs) compared with those of a standard monofocal IOL.

DESIGN

Prospective randomized comparative trial.

PARTICIPANTS

Subjects were divided into 3 groups. In group 1, 30 eyes (19 subjects) received 1CU IOL implantation; in group 2, 29 eyes (19 subjects) received AT-45 IOL implantation; and in group 3, 21 eyes (21 subjects) were implanted with a monofocal IOL as a control.

INTERVENTION

Cataract surgery with implantation of the 1CU and AT-45 accommodative IOL models in the study groups, and the ACR6D monofocal IOL in the control group.

MAIN OUTCOME MEASURES

Far and near distance visual parameters were assessed at 1, 6, and 12 months after surgery in the accommodative IOL groups, and at 1 and 12 months in the control group. Anterior segment anatomy was investigated by ultrasound biomicroscopy, with and without visual accommodative stimulation.

RESULTS

The accommodative IOL groups significantly differed from the controls in terms of lower near-distance refractive addition (NDRA) and better distance-corrected near visual acuity (DCNVA), with P<0.001 at 1 year. The anterior IOL displacement during accommodation (DeltaACD) was significantly larger in the study groups, and this correlated with DCNVA. Until 6 months, the DeltaACD correlated with the solicited sclerociliary process rotation only in the study groups.

CONCLUSION

This 12-month study demonstrated that the accommodating IOLs achieved better clinical results than the monofocal IOL in terms of DCNVA and NDRA. These results support the hypothesis that accommodative IOLs proportionally react to ciliary body rotation, although this relationship became less evident at 12 months.

Anterior capsule cover and axial movement of intraocular lens

PURPOSE

To measure optic shift (OS) of a single piece monofocal intraocular lens (IOL) with varying relationships between anterior capsule cover and IOL optic.

METHODS

This is a prospective randomized masked study of 150 eyes undergoing phacoemulsification. Eyes received either option: 360 degrees total capsule cover (group I); partial cover (group II); or no cover (group III). OS was calculated as difference in anterior chamber depth after administration of cyclopentolate 1% and pilocarpine 2% on IOLMaster at separate visits at 6 months follow-up. Subsequently, using retro-illumination photographs, percentage area of capsule cover was calculated. OS within and between groups I and II was analyzed. The impact of one quartile change in area of capsule cover on percentage change in OS was measured for both groups. Unpaired t-test, correlation, and regression were applied.

RESULTS

In groups I, II, and III, mean age of patients was 56.68+/-6.38, 57.09+/-7.34, 59.15+/-6.35 years, respectively; mean OS (mm) was 1.25+/-0.28, 1.20+/-0.24; 0.95+/-0.26 (P=0.013), respectively; and percentage area of capsule cover (%) was 47.35+/-10.48, 33.83+/-10.11, 0.16+/-0.13 (P=0.001), respectively. Mean percentage area of capsule cover in group I vsgroup II was significant (P=0.001). OS was 1.22+/-0.26 mm in groups I and II (combined) vs0.95+/-0.26 mm in group III (P=0.004, (0.06, 0.33)). OS in group I vsgroup II was not significant (P=0.46). Correlation coefficient was r=0.38 (P<0.001). With every increment on quartile (a quartile is any of the three values which divide the sorted data set into four equal parts, so that each part represents one-fourth of the sample or population) class of area of capsule cover the OS increased by 0.12 mm.

CONCLUSION

The OS differed significantly between total and partial cover groups combined vsno cover group.

Meta-analysis of accommodating intraocular lenses

Accommodating intraocular lenses (IOLs) based on the concept of optic shift were introduced to restore accommodation after cataract surgery. Currently, 3 types of accommodating IOLs are commercially available: 1CU (HumanOptics), BioComFold (Morcher), and AT-45 Crystalens (eyeonics, Inc.). We present a meta-analysis of the peer-reviewed data from studies of these IOLs that use optic-shift measurements and visual acuity as the main outcome measures. In the 6 randomized controlled studies, 5 of which studied the 1CU IOL, the visual acuity results showed moderate to no improvement in near visual acuity compared with control IOLs and a statistically significant but small and inter-patient variable anterior shift of the IOL optic after pilocarpine stimulation. More clinical trials with randomized, controlled, and patient- and examiner-masked study designs that follow the guidelines of evidence-based medicine are needed to prove a benefit of accommodating focus-shift IOLs.

Optimum target refraction for highly and moderately myopic patients after monofocal intraocular lens implantation

PURPOSE

To determine the optimum target refraction for myopic patients who want to see at both near and intermediate distances without correction after cataract surgery.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

Sixty-nine eyes of 69 patients scheduled for phacoemulsification and monofocal intraocular lens (IOL) implantation were studied. The following age groups were recruited: 50s, 60s, and 70s. With addition of a spherical lens of 1.0, 1.5, 2.0, 2.5, or 3.0 diopters (D) after best distance correction (simulation of various degrees of myopia), visual acuity at various distances was measured using the all-distance vision tester. With the assumption that visual acuity of 20/30 is necessary for near and intermediate vision, the distances at which the mean visual acuity reached 20/30 were determined.

RESULTS

Six patients did not have all examinations; thus, 24 patients in the 50s group, 23 in the 60s group, and 22 in the 70s group were included in the analysis. With simulation of -1.0 or -1.5 D of myopia, sufficient near visual acuity at 0.3 m was not obtained. With -2.0 D of myopia, visual acuity better than 20/30 was obtained at 0.7 m, 0.5 m, and 0.3 m. However, with -2.5 D of myopia, visual acuity reached 20/30 at 0.5 m and 0.3 m; with -3.0 D of myopia, it reached only 20/30 at 0.3 m. There were no significant differences between the age groups in mean visual acuity from far to near distances except for intermediate visual acuity with -1.0 D and -1.5 D of myopia and for near visual acuity with -2.5 D of myopia.

CONCLUSIONS

Eyes with a monofocal IOL that simulates -2.0 D of myopia achieved sufficient visual acuity for both near and intermediate distances in 3 age groups. This indicates that -2.0 D is the optimum target refraction in myopic eyes.