Cost-effectiveness and cost-utility of a digital technology-driven hierarchical healthcare screening pattern in China.

Utilization of digital technologies for cataract screening in primary care is a potential solution for addressing the dilemma between the growing aging population and unequally distributed resources. Here, we propose a digital technology-driven hierarchical screening (DH screening) pattern implemented in China to promote the equity and accessibility of healthcare. It consists of home-based mobile artificial intelligence (AI) screening, community-based AI diagnosis, and referral to hospitals. We utilize decision-analytic Markov models to evaluate the cost-effectiveness and cost-utility of different cataract screening strategies (no screening, telescreening, AI screening and DH screening). A simulated cohort of 100,000 individuals from age 50 is built through a total of 30 1-year Markov cycles. The primary outcomes are incremental cost-effectiveness ratio and incremental cost-utility ratio. The results show that DH screening dominates no screening, telescreening and AI screening in urban and rural China. Annual DH screening emerges as the most economically effective strategy with 341 (338 to 344) and 1326 (1312 to 1340) years of blindness avoided compared with telescreening, and 37 (35 to 39) and 140 (131 to 148) years compared with AI screening in urban and rural settings, respectively. The findings remain robust across all sensitivity analyses conducted. Here, we report that DH screening is cost-effective in urban and rural China, and the annual screening proves to be the most cost-effective option, providing an economic rationale for policymakers promoting public eye health in low- and middle-income countries.

Comparing the impact of three-dimensional digital visualization technology versus traditional microscopy on microsurgeons in microsurgery: a prospective self-controlled study.

BACKGROUND: Emerging three-dimensional digital visualization technology (DVT) provides more advantages than traditional microscopy in microsurgery; however, its impact on microsurgeons' visual and nervous systems and delicate microsurgery is still unclear, which hinders the wider implementation of DVT in digital visualization for microsurgery. METHODS AND MATERIAL: Forty-two microsurgeons from the Zhongshan Ophthalmic Center were enrolled in this prospective self-controlled study. Each microsurgeon consecutively performed 30 min conjunctival sutures using a three-dimensional digital display and a microscope, respectively. Visual function, autonomic nerve activity, and subjective symptoms were evaluated before and immediately after the operation. Visual functions, including accommodative lag, accommodative amplitude, near point of convergence and contrast sensitivity function (CSF), were measured by an expert optometrist. Heart rate variability was recorded by a wearable device for monitoring autonomic nervous activity. Subjective symptoms were evaluated by questionnaires. Microsurgical performance was assessed by the video-based Objective Structured Assessment of Technical Skill (OSATS) tool. RESULTS: Accommodative lag decreased from 0.63 (0.18) diopters (D) to 0.55 (0.16) D ( P =0.014), area under the log contrast sensitivity function increased from 1.49 (0.15) to 1.52 (0.14) ( P =0.037), and heart rate variability decreased from 36.00 (13.54) milliseconds (ms) to 32.26 (12.35) ms ( P =0.004) after using the DVT, but the changes showed no differences compared to traditional microscopy ( P >0.05). No statistical significance was observed for global OSATS scores between the two rounds of operations [mean difference, 0.05 (95% CI: -1.17 to 1.08) points; P =0.95]. Subjective symptoms were quite mild after using both techniques. CONCLUSIONS: The impact of DVT-based procedures on microsurgeons includes enhanced accommodation and sympathetic activity, but the changes and surgical performance are not significantly different from those of microscopy-based microsurgery. Our findings indicate that short-term use of DVT is reliable for microsurgery and the long-term effect of using DVT deserve more consideration.

Comparison of robot-assisted vitreoretinal surgery and manual surgery in different preclinical settings: a randomized trial.

Background: Progress in the field of surgical robotics has the potential to allow surgeons to reduce the limitations of human hands and has substantially improved the dexterity and accuracy of surgery. This study aimed to compare robot-assisted vitreoretinal surgery with manual surgery in a simulated setting involving donor porcine eyes. Methods: A randomized controlled trial was conducted involving 10 experienced vitreoretinal experts and 10 residents. Participants were randomized to start with either manual or robot-assisted surgery (n=5 in each group). Participants completed 3 tests consisting of 2 vitreoretinal modules on a virtual-reality simulator and microcannulation in donor porcine eyes. The primary outcome measures were as follows: test completion time, surgical accuracy and tremor control provided by the simulator, and the feasibility of microcannulation in donor porcine eyes. Results: Robot-assisted surgery supported better accuracy and tremor control than manual surgery for vitreoretinal experts (P=0.028 and P=0.002, respectively) and residents (P=0.025 and P<0.001, respectively). Residents improved their microcannulation performance with the assistance of the robot (P=0.038) to a level comparable to that of experts (P=0.49). Robot-assisted surgery was less time-efficient than manual surgery for both residents (P<0.001) and vitreoretinal experts (P<0.001). Conclusions: Compared with manual surgery, robot-assisted vitreoretinal surgery improves the stability of instrument handling and the accuracy of surgery. Robot-assisted surgeries have the potential to shorten the learning curve for residents and improve surgical performance.

Intelligent cataract surgery supervision and evaluation via deep learning.

PURPOSE: To assess the performance of a deep learning (DL) algorithm for evaluating and supervising cataract extraction using phacoemulsification with intraocular lens (IOL) implantation based on cataract surgery (CS) videos. MATERIALS AND METHODS: DeepSurgery was trained using 186 standard CS videos to recognize 12 CS steps and was validated in two datasets that contained 50 and 21 CS videos, respectively. A supervision test including 50 CS videos was used to assess the DeepSurgery guidance and alert function. In addition, a real-time test containing 54 CSs was used to compare the DeepSurgery grading performance to an expert panel and residents. RESULTS: DeepSurgery achieved stable performance for all 12 recognition steps, including the duration between two pairs of adjacent steps in internal validation with an ACC of 95.06% and external validations with ACCs of 88.77% and 88.34%. DeepSurgery also recognized the chronology of surgical steps and alerted surgeons to order of incorrect steps. Six main steps are automatically and simultaneously quantified during the evaluation process (centesimal system). In a real-time comparative test, the DeepSurgery step recognition performance was robust (ACC of 90.30%). In addition, DeepSurgery and an expert panel achieved comparable performance when assessing the surgical steps (kappa ranged from 0.58 to 0.77). CONCLUSIONS: DeepSurgery represents a potential approach to provide a real-time supervision and an objective surgical evaluation system for routine CS and to improve surgical outcomes.

Automated detection of retinal exudates and drusen in ultra-widefield fundus images based on deep learning.

BACKGROUND: Retinal exudates and/or drusen (RED) can be signs of many fundus diseases that can lead to irreversible vision loss. Early detection and treatment of these diseases are critical for improving vision prognosis. However, manual RED screening on a large scale is time-consuming and labour-intensive. Here, we aim to develop and assess a deep learning system for automated detection of RED using ultra-widefield fundus (UWF) images. METHODS: A total of 26,409 UWF images from 14,994 subjects were used to develop and evaluate the deep learning system. The Zhongshan Ophthalmic Center (ZOC) dataset was selected to compare the performance of the system to that of retina specialists in RED detection. The saliency map visualization technique was used to understand which areas in the UWF image had the most influence on our deep learning system when detecting RED. RESULTS: The system for RED detection achieved areas under the receiver operating characteristic curve of 0.994 (95% confidence interval [CI]: 0.991-0.996), 0.972 (95% CI: 0.957-0.984), and 0.988 (95% CI: 0.983-0.992) in three independent datasets. The performance of the system in the ZOC dataset was comparable to that of an experienced retina specialist. Regions of RED were highlighted by saliency maps in UWF images. CONCLUSIONS: Our deep learning system is reliable in the automated detection of RED in UWF images. As a screening tool, our system may promote the early diagnosis and management of RED-related fundus diseases.

Associations Between Regional Environment and Cornea-Related Morphology of the Eye in Young Adults: A Large-Scale Multicenter Cross-Sectional Study.

Purpose: To investigate environmental factors associated with corneal morphologic changes. Methods: A cross-sectional study was conducted, which enrolled adults of the Han ethnicity aged 18 to 44 years from 20 cities. The cornea-related morphology was measured using an ocular anterior segment analysis system. The geographic indexes of each city and meteorological indexes of daily city-level data from the past 40 years (1980-2019) were obtained. Correlation analyses at the city level and multilevel model analyses at the eye level were performed. Results: In total, 114,067 eyes were used for analysis. In the correlation analyses at the city level, the corneal thickness was positively correlated with the mean values of precipitation (highest r [correlation coefficient]: >0.700), temperature, and relative humidity (RH), as well as the amount of annual variation in precipitation (r: 0.548 to 0.721), and negatively correlated with the mean daily difference in the temperature (DIF T), duration of sunshine, and variance in RH (r: -0.694 to 0.495). In contrast, the anterior chamber (AC) volume was negatively correlated with the mean values of precipitation, temperature, RH, and the amount of annual variation in precipitation (r: -0.672 to -0.448), and positively associated with the mean DIF T (r = 0.570) and variance in temperature (r = 0.507). In total 19,988 eyes were analyzed at the eye level. After adjusting for age, precipitation was the major explanatory factor among the environmental factors for the variability in corneal thickness and AC volume. Conclusions: Individuals who were raised in warm and wet environments had thicker corneas and smaller AC volumes than those from cold and dry ambient environments. Our findings demonstrate the role of local environmental factors in corneal-related morphology.

Polar value analysis of astigmatic change and rotational stability after implantation of V4c toric implantable collamer lens.

BACKGROUND: To evaluate the clinical results and rotational stability of V4c toric implantable collamer lens (TICL, STAAR Surgical Company, Monrovia, CA, USA) in patients with moderate to high myopic astigmatism. Retrospective, interventional case series was performed at Shenzhen Eye Hospital, Shenzhen, Guangdong, China. METHODS: This study enrolled 43 patients (72 eyes) who received TICL implantation to correct myopia and myopic astigmatism. The patients underwent visual and refractive examinations before and 1 month after surgery. Astigmatic changes were estimated using polar value analysis. The difference between the achieved axis and the intended axis at the last follow-up was taken as the rotation of the V4c TICL. RESULTS: At 1 month postoperatively, the mean safety and efficacy indices were 1.17 and 1.13, respectively. A significant reduction of 8.92±2.58 D was observed in the spherical equivalent refraction (SER), which decreased from -9.29±2.41 D preoperatively to -0.37±0.55 D postoperatively. The astigmatic error of treatment in cylinder format was calculated to 0.50±0.41 @ 15.08° relative to the preoperative stronger meridian at 1 month, postoperatively. At 1 month postoperatively, the mean absolute rotation was 8.30±10.00 degrees (median =5.46 degrees; range, 0.00-58.88 degrees). CONCLUSIONS: TICL could achieve good astigmatic outcomes for correcting moderate to high myopic astigmatism. After TICL implantation, corneal astigmatism remained unchanged. To optimize postoperative astigmatic outcomes in TICL, polar value analysis can be used to build a nomogram.

Deep learning for automated glaucomatous optic neuropathy detection from ultra-widefield fundus images.

BACKGROUND/AIMS: To develop a deep learning system for automated glaucomatous optic neuropathy (GON) detection using ultra-widefield fundus (UWF) images. METHODS: We trained, validated and externally evaluated a deep learning system for GON detection based on 22 972 UWF images from 10 590 subjects that were collected at 4 different institutions in China and Japan. The InceptionResNetV2 neural network architecture was used to develop the system. The area under the receiver operating characteristic curve (AUC), sensitivity and specificity were used to assess the performance of detecting GON by the system. The data set from the Zhongshan Ophthalmic Center (ZOC) was selected to compare the performance of the system to that of ophthalmologists who mainly conducted UWF image analysis in clinics. RESULTS: The system for GON detection achieved AUCs of 0.983-0.999 with sensitivities of 97.5-98.2% and specificities of 94.3-98.4% in four independent data sets. The most common reasons for false-negative results were confounding optic disc characteristics caused by high myopia or pathological myopia (n=39 (53%)). The leading cause for false-positive results was having other fundus lesions (n=401 (96%)). The performance of the system in the ZOC data set was comparable to that of an experienced ophthalmologist (p>0.05). CONCLUSION: Our deep learning system can accurately detect GON from UWF images in an automated fashion. It may be used as a screening tool to improve the accessibility of screening and promote the early diagnosis and management of glaucoma.

Deep learning from "passive feeding" to "selective eating" of real-world data.

Artificial intelligence (AI) based on deep learning has shown excellent diagnostic performance in detecting various diseases with good-quality clinical images. Recently, AI diagnostic systems developed from ultra-widefield fundus (UWF) images have become popular standard-of-care tools in screening for ocular fundus diseases. However, in real-world settings, these systems must base their diagnoses on images with uncontrolled quality ("passive feeding"), leading to uncertainty about their performance. Here, using 40,562 UWF images, we develop a deep learning-based image filtering system (DLIFS) for detecting and filtering out poor-quality images in an automated fashion such that only good-quality images are transferred to the subsequent AI diagnostic system ("selective eating"). In three independent datasets from different clinical institutions, the DLIFS performed well with sensitivities of 96.9%, 95.6% and 96.6%, and specificities of 96.6%, 97.9% and 98.8%, respectively. Furthermore, we show that the application of our DLIFS significantly improves the performance of established AI diagnostic systems in real-world settings. Our work demonstrates that "selective eating" of real-world data is necessary and needs to be considered in the development of image-based AI systems.

Development and Evaluation of a Deep Learning System for Screening Retinal Hemorrhage Based on Ultra-Widefield Fundus Images.

Purpose: To develop and evaluate a deep learning (DL) system for retinal hemorrhage (RH) screening using ultra-widefield fundus (UWF) images. Methods: A total of 16,827 UWF images from 11,339 individuals were used to develop the DL system. Three experienced retina specialists were recruited to grade UWF images independently. Three independent data sets from 3 different institutions were used to validate the effectiveness of the DL system. The data set from Zhongshan Ophthalmic Center (ZOC) was selected to compare the classification performance of the DL system and general ophthalmologists. A heatmap was generated to identify the most important area used by the DL model to classify RH and to discern whether the RH involved the anatomical macula. Results: In the three independent data sets, the DL model for detecting RH achieved areas under the curve of 0.997, 0.998, and 0.999, with sensitivities of 97.6%, 96.7%, and 98.9% and specificities of 98.0%, 98.7%, and 99.4%. In the ZOC data set, the sensitivity of the DL model was better than that of the general ophthalmologists, although the general ophthalmologists had slightly higher specificities. The heatmaps highlighted RH regions in all true-positive images, and the RH within the anatomical macula was determined based on heatmaps. Conclusions: Our DL system showed reliable performance for detecting RH and could be used to screen for RH-related diseases. Translational Relevance: As a screening tool, this automated system may aid early diagnosis and management of RH-related retinal and systemic diseases by allowing timely referral.

Deep learning for detecting retinal detachment and discerning macular status using ultra-widefield fundus images.

Retinal detachment can lead to severe visual loss if not treated timely. The early diagnosis of retinal detachment can improve the rate of successful reattachment and the visual results, especially before macular involvement. Manual retinal detachment screening is time-consuming and labour-intensive, which is difficult for large-scale clinical applications. In this study, we developed a cascaded deep learning system based on the ultra-widefield fundus images for automated retinal detachment detection and macula-on/off retinal detachment discerning. The performance of this system is reliable and comparable to an experienced ophthalmologist. In addition, this system can automatically provide guidance to patients regarding appropriate preoperative posturing to reduce retinal detachment progression and the urgency of retinal detachment repair. The implementation of this system on a global scale may drastically reduce the extent of vision impairment resulting from retinal detachment by providing timely identification and referral.

Polar Value Analysis of Low to Moderate Astigmatism with Wavefront-Guided Sub-Bowman Keratomileusis.

PURPOSE: To evaluate the astigmatic outcomes of wavefront-guided sub-Bowman keratomileusis (WFG-SBK) for low to moderate myopic astigmatism. METHODS: This study enrolled 100 right eyes from 100 patients who underwent WFG-SBK for the correction of myopia and astigmatism. The polar value method was performed with anterior and posterior corneal astigmatism measured with Scheimpflug camera combined with Placido corneal topography (Sirius, CSO) and refractive astigmatism preoperatively and 1 month, 3 months, and 6 months postoperatively. RESULTS: Similar results for surgically induced astigmatism (SIA) and error of the procedure in both anterior corneal astigmatism (ACA) and total ocular astigmatism (TOA). There was a minor undercorrection of the cylinder in both ACA and TOA. Posterior corneal astigmatism (PCA) showed no significant change. CONCLUSIONS: Wavefront-guided SBK could provide good astigmatic outcomes for the correction of low to moderate myopic astigmatism. The surgical effects were largely attributed to the astigmatic correction of the anterior corneal surface. Posterior corneal astigmatism remained unchanged even after WFG-SBK for myopic astigmatism. Polar value analysis can be used to guide adjustments to the treatment cylinder alongside a nomogram designed to optimize postoperative astigmatic outcomes in myopic WFG-SBK.

The Effect of High Intensity Focused Ultrasound Keratoplasty on Rabbit Anterior Segment.

Purpose. To evaluate the safety of high-intensity focused ultrasound keratoplasty as a treatment for presbyopia by examining its effect on the rabbit anterior segment. Methods. The right corneas of 36 New Zealand rabbits were treated with HIFU keratoplasty. The animals were sacrificed at 1, 7, 15, 30, 60, and 90 days after operation. Collagen type I, MMP-2, and MMP-9 were evaluated using immunohistochemistry. For the detection of apoptosis, the TUNEL method was applied. The SOD and MDA levels were analyzed with assay kits. Results. Collagen type I, MMP-2, and MMP-9 levels were altered after the operation but returned to normal within 90 days. The apoptotic index (AI) of the corneal cells decreased from 1 to 30 days gradually. No apoptosis was observed in the epithelial cells of the lens, and the SOD and MDA levels were normal at any time point. Conclusion. After HIFU keratoplasty, the histomorphology of the cornea changed, the corneal collagen type I levels decreased, the corneal MMP-2 and MMP-9 levels increased, and the corneal cells underwent apoptosis for a period of time. Ninety days after the operation, the levels returned to normal, and the lenses were not affected. Thus, HIFU presents good biological safety for eyes.

Keratorefractive Effect of High Intensity Focused Ultrasound Keratoplasty on Rabbit Eyes.

Purpose. To evaluate high intensity focused ultrasound (HIFU) as an innovation and noninvasive technique to correct presbyopia by altering corneal curvature in the rabbit eye. Methods. Eighteen enucleated rabbit eyes were treated with a prototype HIFU keratoplasty. According to the therapy power, these eyes were divided three groups: group 1 (1 W), group 2 (2 W), and group 3 (3 W). The change in corneal power was quantified by a Sirius Scheimpflug camera. Light microscopy (LM) and transmission electron microscopy (TEM) were performed to determine the effect on the corneal stroma. Results. In the treated eyes, the corneal curvature increases from 49.42 ± 0.30 diopters (D) and 48.00 ± 1.95 D before procedure to 51.37 ± 1.11 D and 57.00 ± 1.84 D after HIFU keratoplasty application in groups 1 and 3, respectively. The major axis and minor axis of the focal region got longer when the powers of the HIFU got increased; the difference was statistically significant (p < 0.05). LM and TEM showed HIFU-induced shrinkage of corneal stromal collagen with little disturbance to the underlying epithelium. Conclusions. We have preliminarily exploited HIFU to establish a new technique for correcting presbyopia. HIFU keratoplasty will be a good application prospect for treating presbyopia.

[Evaluation of quality of vision in early stage after sub-bowman keratomileusis].

OBJECTIVE: To assess the quality of vision in the early stage after sub-bowman keratomileusis (SBK) for the correction of moderate and high myopia. METHODS: Retrospective case series. Sixty eight myopic eyes of 35 consecutive patients in Chongqing Medal Eye Institute from May to November 2011 were enrolled in this study. All patients were evaluated at 2 weeks, 1 and 3 months postoperatively. The main measurements included visual acuity, corneal and total optical wavefront aberration, photopic and mesopic contrast sensitivity. RESULTS: The median values of preoperative uncorrected central visual acuity (UCVA) and best corrected visual acuity (BCVA) were 0.05 and 1.00, respectively. The median value of postoperative UCVA was 1.20. There was no significant difference between the preoperative and postoperative anterior corneal total aberration (F = 0.712, P > 0.05). Compared with preoperative value (0.47 ± 0.17)µm, the corneal high orders aberrations in 2 weeks after SBK (1.37 ± 0.72) µm increased by 3 times. The total optical aberrations in 2 weeks after SBK (0.99 ± 0.58) µm decreased to one-eighth of preoperative measurements (8.26 ± 2.93) µm. Compared with preoperative value (0.30 ± 0.12)µm, the total high order aberrations in 2 weeks after SBK (0.46 ± 0.19) µm increased by 1.5 times. Although photopic and mesopic contrast sensitivity fluctuated mildly after SBK, the measurements did not decline significantly. Compared with preoperative data, mesopic contrast sensitivity at 3 months increased 0.294 (F = 20.88,P < 0.01) and 0.296 (F = 13.64, P < 0.01) at 12 and 18 c/d, respectively. CONCLUSION: Patients could obtain good quality of vision at the early stage after SBK.

Anterior segment variations after posterior chamber phakic intraocular lens implantation in myopic eyes.

PURPOSE: To evaluate anterior segment variations after posterior chamber phakic intraocular lens (pIOL) implantation in myopic eyes. SETTING: Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. DESIGN: Cohort study. METHODS: Patients with high myopia were scheduled for nontoric Implantable Collamer Lens pIOL or toric Implantable Collamer Lens pIOL implantation. Anterior segment optical coherence tomography was performed to evaluate the anterior segment variations over time and the impact of physiologic accommodation and change in brightness after pIOL implantation. Slitlamp photography of the anterior segment was taken after pupil dilation to calculate pIOL rotation. RESULTS: There was significantly improved visual acuity and refractive status after implantation of both pIOLs. Anterior segment axial variations had good stability 6 months postoperatively. However, nontoric pIOL rotation occurred in 1 eye 7 months postoperatively and rotation of the toric pIOL occurred in 2 eyes at 3 months and 6 months. Stimulations of -4.0 diopters (D) and -8.0 D led to significant changes in anterior chamber depth (ACD) based on the lens (ACD-lens), ACD after pIOL implantation, distance between the pIOL posterior surface and the lens anterior surface (pIOL-lens), and pupil diameter. Increasing ambient light brightness could reduce the ACD-lens and pIOL-lens. CONCLUSIONS: Both pIOLs had good axial stability in myopic eyes 6 months postoperatively; however, rotational stability over time could not be determined. The physiologic adjustment and change in brightness could influence the anterior segment significantly in eyes with a pIOL.

Minor influence of sub-bowman keratomileusis on the posterior corneal surface at early stage.

PURPOSE: To evaluate the changes in posterior corneal surface (Q value and elevation) measured with Pentacam after femtosecond laser assisted Sub-Bowman Keratomileusis (SBK). METHODS: The Q values and elevation of posterior corneal surface were determined in 166 myopic/myopic astigmatism eyes of 88 patients using Scheimpflug imaging (Pentacam; Oculus, Wetzlar, Germany), which estimates asphericity and elevation for several areas of cornea analysed (Q value: 6, 7, 8 and 9 mm; elevation: 2, 4, 6 and 8 mm) before 1 and 3 months after SBK. The correlations between the changes of Q value or elevation and the mean preoperative spherical equivalent (SE), central corneal thickness (CCT), central ablation depth (AD), estimated residual bed thickness (RBT) and RBT/CCT ratio were investigated. RESULTS: Meridian and area differences in Q of posterior surface have been showed. Two major meridians (horizontal/vertical) present the change of significant negative direction before surgery (all p < 0.001), but the alteration of significant positive direction for all post-SBK follow-up visits (all p < 0.05). There was no statistically significant difference in posterior elevation at 2 mm zone (horizontal meridian: p = 0.439; vertical meridian: p = 0.233). Compared with preoperation, minor but significant forward displacements were found in posterior elevation at 4 and 6 mm areas of cornea analyzed (horizontal meridian: all p < 0.001; vertical meridian: p < 0.001, p = 0.024, respectively). However, posterior elevation in two meridians (horizontal/vertical) at 8 mm region was displayed significant backward shift (p = 0.001, p < 0.001, respectively). The Pearson correlation test showed no significant correlation between the changes in the Q values and elevation data in vast majority of areas of cornea analyzed and the SE, CCT, AD, RBT, and RBT/CCT ratio at 1 and 3 months after surgery (all p > 0.05). CONCLUSIONS: The posterior corneal surface showed central flattening and peripheral steepening at early stage post-SBK. To combine the asphericity with the elevation of the posterior corneal surface can overall and accurately understand the posterior corneal shape and its variations after refractive surgery.

Anterior segment variations with age and accommodation demonstrated by slit-lamp-adapted optical coherence tomography.

OBJECTIVE: To investigate anterior segment variations with age and accommodation by slit-lamp-adapted optical coherence tomography (SL-OCT) and determine a safe central vault distance between the implantable contact lens (ICL) and the crystalline lens to avoid contact cataract formation. DESIGN: Evaluation of diagnostic test or technology. PARTICIPANTS: Eighty-six patients (126 eyes) under regular review from the Optometry Clinic and Outpatient Department in Zhongshan Ophthalmic Center. METHODS: Patients underwent anterior segment measurements, such as anterior chamber depth (ACD), anterior chamber width (ACW), crystalline lens rise (CLR), and pupil diameter (PD), with the SL-OCT system manufactured by Heidelberg Engineering GmbH, Heidelberg, Germany. Data were analyzed with SPSS software (version 16.0, SPSS, Inc., Chicago, IL). MAIN OUTCOME MEASURES: Anterior segment parameters and their variations with age and accommodation. RESULTS: The internal vertical ACW (V-ACW) was anatomically larger than the internal horizontal ACW (H-ACW). With age, the ACD decreased approximately 17 µm per year. Forward movement of the crystalline lens' anterior pole decreased approximately 11 µm per year. During physiologic accommodation, the variation in ACD was -24 µm per diopter and the alterations in CLR were 28 µm per diopter. According to our data, a safe lens vault after phakic intraocular lens implantation should be more than 300 µm to reduce complications. CONCLUSIONS: Slit-lamp-adapted optical coherence tomography is a user-friendly instrument for evaluating the anterior segment, especially for accurate anterior chamber biometry, and may offer guidance on minimizing touch and cataract formation after phakic intraocular lens implantation.