Preoperative Anterior Chamber Depth Research Articles

Endothelial Cell Loss in Patients with Phakic Intraocular Lenses.

Although the safety of phakic intraocular lenses (pIOLs) has been continuously improved over 70-years of development, high endothelial cell losses can occur even with current pIOL models. Numerous studies have demonstrated that the distance of a pIOL to the corneal endothelium plays a crucial role in the extent of endothelial cell loss. For this reason alone, higher endothelial cell loss tends to be observed with anterior chamber lenses than with posterior chamber lenses. Adequate preoperative anterior chamber depth is essential, at least for iris-fixed pIOLs, in order to ensure a safe distance from the endothelium. However, the anterior chamber becomes shallower with age and therefore it may be useful to consider patient age in the safety criteria. Although endothelial cell loss is generally low with current pIOL models, regular monitoring of the endothelial cell density remains essential due to large interindividual differences in patients with pIOLs. If the endothelial cell loss is greater than expected and the follow-up visits confirm the trend, the pIOL should be explanted without delay. The endothelial reserve should be considered on an individual basis by taking into account patient age, physiological endothelial cell loss, and loss due to further surgery. With careful indication and long-term patient care, pIOLs remain a safe treatment option.

Risk factors for corneal endothelial cell loss after phacoemulsification.

The purpose of this study was to evaluate the changes in corneal endothelial cell density (CECD) occurring after cataract phacoemulsification surgery and identify factors associated with cell loss. This was a retrospective study involving patients who underwent cataract phacoemulsification surgery between January 1, 2018, and December 31, 2018, at two private hospitals. Demographic data and biometric parameters were obtained preoperatively. Ultrasound metrics were recorded for each operation, including total on time (TOT), total equivalent power in position 3, and cumulative dissipated energy (CDE). Using corneal specular microscopy, CECD was measured preoperatively and postoperatively at 12, 24, and 36 months. Factors associated with decreased CECD were identified. This study included 223 eyes of 133 patients. The mean CECD was 2530.03 ± 285.42 cells/mm2 preoperatively and significantly decreased to 2364.22 ± 386.98 cells/mm2 at 12 months (P < 0.001), 2292.32 ± 319.72 cells/mm2 at 24 months (P < 0.001), and 2242.85 ± 363.65 cells/mm2 at 36 months (P < 0.001). The amount of cell loss was associated with age, gender, preoperative CECD, preoperative anterior chamber depth, lens thickness, TOT, and CDE. Using multivariate analysis, age, preoperative CECD, and TOT were identified as independent predictors for CECD loss 12 months after surgery. The greatest decrease in CECD occurred during the first year after cataract surgery, and the amount of cell loss was influenced by both baseline patient characteristics and ultrasound metrics. Longer-term prospective studies in a larger cohort may yield more information.

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

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. University Hospitals Sussex NHS Foundation Trust, Brighton, United Kingdom. Prospective study. 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. 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. A combination of low myopic SEQ, lower Z 40 , shorter preoperative AL, and smaller PS increases the chances of pseudoaccommodation.

Scheimpflug Corneal Tomography Anterior Chamber Depth in Descemet Stripping Endothelial Keratoplasty Recipients.

Our study investigates whether preoperative anterior chamber depth (ACD) measured by Scheimpflug tomography could serve as a potential predictor of graft failure in eyes undergoing Descemet stripping endothelial keratoplasty (DSEK). A retrospective review was conducted on patients who underwent primary or repeat DSEK between January 2020 and August 2021 at Bascom Palmer Eye Institute. Charts from 378 primary and 192 repeat DSEK patients were reviewed and ultimately 47 primary and 21 repeat DSEK patients met criteria for inclusion. Data collection included demographics, preoperative ACD, best-corrected visual acuity, and length of follow-up. Demographics were similar between groups, and there was no significant difference in the average best-corrected visual acuity between the single and repeat DSEK groups preoperatively. Baseline preoperative ACD was greatest in the single DSEK group (3.51 ± 0.90 mm) when compared to baseline preoperative ACD in the repeat DSEK group (3.01 ± 0.67 mm, P = 0.003). The preoperative mean ACD was smallest in the repeat DSEK group before the second DSEK (2.94 ± 0.48 mm, P = 0.001). Preoperative baseline ACD was the only variable to affect graft survival time significantly (P = 0.012). The incidence of glaucoma diagnosis was similar in both groups (42.5% vs. 42.8%, P = 0.471). The diagnosis of glaucoma and presence of incisional glaucoma surgery did not affect the graft survival time (P = 0.129, P = 0.559) or need for repeat DSEK. Smaller baseline preoperative Scheimpflug ACD measurement may be a possible predictor of the need for repeat DSEK. Our study found that Scheimpflug ACD decreases with subsequent DSEK failure.

Factors Associated with Refractive Prediction Error after Phacotrabeculectomy.

To compare refractive prediction errors between phacotrabeculectomy and phacoemulsification. Refractive prediction error was defined as the difference in spherical equivalent between the predicted value using the Barrett Universal II formula and the actual value obtained at postoperative one month. Forty-eight eyes that had undergone phacotrabeculectomy (19 eyes, open-angle glaucoma; 29 eyes, angle-closure glaucoma) were matched with 48 eyes that had undergone phacoemulsification by age, average keratometry value and axial length (AL), and their prediction errors were compared. The factors associated with prediction errors were analyzed by multivariable regression analyses. The phacotrabeculectomy group showed a larger absolute prediction error than the phacoemulsification group (0.51 ± 0.37 Diopters vs. 0.38 ± 0.22 Diopters, p = 0.033). Larger absolute prediction error was associated with longer AL (p = 0.010) and higher intraocular pressure (IOP) difference (p = 0.012). Hyperopic shift (prediction error > 0) was associated with shallower preoperative anterior chamber depth (ACD) (p = 0.024) and larger IOP difference (p = 0.031). In the phacotrabeculectomy group, the prediction error was inversely correlated with AL: long eyes showed myopic shift and short eyes hyperopic shift (p = 0.002). Surgeons should be aware of the possibility of worse refractive outcomes when planning phacotrabeculectomy, especially in eyes with high preoperative IOP, shallow ACD, and/or extreme AL.

Predicting the postoperative intraocular lens position based on IOL Master 700 biometry, compared with results from the anterior segment analysis system.

Predict intraocular lens position after cataract surgery using the IOL Master 700 and explore the associated ocular parameters compared with the results obtained from the anterior segment analysis system (Sirius, CSO Inc, Florence, Italy). A total of 98 patients (106 eyes) were included in the retrospective study. The postoperative intraocular lens position was obtained using the IOL Master 700 and measured using Adobe Illustrator software. Correlation analysis and linear regression analysis were applied to study the correlation between the actual position of the postoperative intraocular lens (ALP) and the ocular parameters. In addition, Bland-Altman consistency analysis was used to compare the consistency between any two among the predicted intraocular lens position (ALPi) obtained using IOL Master 700 biometry, the predicted artificial lens position (ALPs) calculated using the anterior segment analysis system, or the ALP. Ocular parameters, including preoperative anterior chamber depth, lens thickness, axial length, white-to-white, and postoperative refractive error were all correlated with ALP after cataract surgery (P < 0.05) using univariate analysis. However, in multivariate linear regression, only the first three variables were correlated with ALP. Compared with the equation obtained by the anterior segment analysis, the equation from IOL Master 700 biometry provided a better fit. The results of the consistency analysis showed that ALP, ALPi, and ALPs were in good agreement. IOL Master 700 biometry can help predict intraocular lens position after surgery, and its accuracy is better than that provided by the anterior segment analysis system.

Evaluation of Higher Order Aberrations and Anterior Segment Parameters Changes After Implantable Collamer Lens Implantation for High Myopia.

To evaluate changes in higher order aberrations (HOAs) induced by implantable collamer lens (ICL) implantation in correction of high myopia and to compare the anterior segment parameters before and after surgery. Also, to correlate these parameters with HOAs, the best corrected visual acuity (BCVA) and intraocular pressure (IOP). This prospective interventional cohort case series study included 40 eyes with high myopia that underwent ICL V4c implantation. They were evaluated pre-operatively and post-operatively at 1st and 3rd month HOAs using Scheimpflug Sirius Camera. The anterior segment parameters were evaluated by optical biometry. Correlations between HOAs, BCVA and anterior segment parameters were evaluated. The mean pre-operative BCVA was 0.67 ± 0.17, while post-operative BCVA was 0.74 ± 0.16 (p-value < 0.001). The spherical equivalent was -13.66 ± 2.23 pre-operatively, while post-operatively it was -0.77 ± 0.65 (p-value < 0.001). The mean pre-operative root mean square (RMS) of HOAs was 0.62 ± 0.11 µm, while mean post-operative RMS in the 1st month was 0.82 ± 0.29 µm (p-value < 0.001). At 3rd month, it was 0.63 ± 0.17 µm (p-value = 0.685). The mean pre-operative anterior chamber depth (ACD) was 3.66 ± 0.26 mm. It decreased in the post-operative 1st month to 3.46 ± 0.30 mm, while in 3rd month 3.45 ± 0.24 mm (p-value < 0.001, < 0.001) respectively. The mean pre-operative anterior chamber angle (ACA) 45.98 ± 8.39 o while, the mean ACA was 31.65 ± 4.14, 31.03 ± 3.74 post-operatively (p-value < 0.001, < 0.001) respectively. There was significant increase in IOP (p-value < 0.001). ICL implantation is safe and effective in correction of high myopia, as HOAs increase at first month post-operatively then, return to the pre-operative level by 3rd month. However, anterior segment parameters show significant changes which may need longer follow up.

Changes in corneal endothelial cell density after trabeculectomy.

Glaucoma is a leading cause of blindness worldwide for which trabeculectomy is the most effective surgical intervention for advanced disease. However, trabeculectomy has been associated with alterations to corneal endothelium, including a decrease in corneal endothelial cell density (CECD). The purpose of this study was to investigate changes in CECD after trabeculectomy, and identify factors contributing to cell loss, such as pre-operative biometry and lens status. This retrospective study included 72 eyes of 60 patients who underwent trabeculectomy between January 2018 and June 2021 at two private hospitals. Demographic and clinical data were obtained at baseline. Corneal specular microscopy was performed pre-operatively and at 6 months after surgery. CECD was evaluated and compared between groups to quantify changes to corneal endothelium and identify significant factors affecting decreases in cell density. Mean CECD was 2284.66 ± 375.59 pre-operatively and 2129.52 ± 401.96 after 6 months (p < 0.001). A greater decrease in CECD (p = 0.005) was observed in phakic eyes (235.45 ± 118.32) compared to pseudophakic eyes (137.82 ± 107.30). The amount of cell loss was negatively correlated with pre-operative central corneal thickness (p = 0.009) and anterior chamber (AC) depth (p = 0.033). There were no significant correlations between changes to CECD and patient age, gender, number of pre-operative glaucoma medications and number of post-operative antifibrotic agents. Significant decreases in CECD occurred after trabeculectomy. Less corneal endothelial cell loss occurred in pseudophakic eyes. Hence, if patients need trabeculectomy and cataract surgery, it may be better to perform cataract surgery first. Longer term studies should derive more information.

Evaluation of Ocular Biometric Parameters Following Cataract Surgery

Background: The aim of this study was to highlight the structural changes in patients with cataract following surgery and the repercussions on the anterior pole. Methods: A total of 83 patients diagnosed with cataract who underwent uneventful phacoemulsification was included. Every patient was examined one week prior to and two weeks after the surgery. Pre- and postoperative assessment included examination of the anterior and posterior segment, keratometry, and optical biometry. Results: The pre- vs. postoperative axial length (AL) mean difference was 0.07 ± 0.18 mm (p &lt; 0.001).The mean difference of the postoperative anterior chamber depth (ACD) vs. preoperative ACD values (1.11 ± 0.50 mm) was also statistically significant (p &lt; 0.001). The linear regression function postoperative central corneal thickness (CCT) = 0.9004 × (preoperative CCT) + 0.0668, where it characterized a reduced positive correlation (R2) of 68.89% between the postoperative CCT and preoperative CCT. The mean pre-/post-operative differences in the K1 values were 0.08 ± 0.38 D, with a statistically significant difference between the two datasets (p = 0.0152). The mean pre/postoperative difference in the K2 values was 0.002 ± 0.58 D (p = 0.4854). Conclusions: ACD deepened significantly postoperatively. Regarding AL, there was a decrease after surgery, and a very good positive correlation between the post and preoperative values. The CCT values decreased with age. The 2.2-mm corneal incision during cataract surgery resulted in a relatively small postoperative residual astigmatism.

ICL Postimplantation Decentration and Tilt in Myopic Patients with Primary Iridociliary Cysts.

To observe the decentration and tilt of implantable collamer lens (ICL) as well as possible visual effects postimplantation in primary iridociliary cysts. The present investigation was a retrospective cohort study. All 48 patients (91 eyes) who underwent ICL surgery at the Center of Refraction Surgery of Tianjin Medical University Eye Hospital between July 2018 and May 2020 were split into two groups based on the absence or presence of primary iridociliary cysts established by ultrasonic biological microscopy (UBM) examination. Intraocular pressure (IOP), corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), anterior chamber angle (ACA), anterior chamber volume (ACV), and anterior chamber depth (ACD) were recorded preoperatively and postoperatively at 1, 6, and 12 months. Additionally, we performed an analysis of the ICL vault, decentration, and tilt using a rotating Scheimpflug Oculus Pentacam camera system at 1, 6, and 12 months after surgery. No serious complications were observed. Significant postoperative improvement (P < 0.05) of UDVA was established in the two studied groups; however, we did not observe statistically significant intergroup differences (P > 0.05) throughout the entire research period. In each group, the preoperative ACA, ACV, and ACD were statistically significantly reduced (P < 0.05), but no such decrease was established between their postoperative values (P > 0.05). We observed no statistical differences between both groups with regard to their values of IOP, ACA, ACV, ACD, ICL vault, ICL decentration, and tilt at 1, 6, and 12 months after surgery. Similarly, no statistically significant within-group correlation (P > 0.05) of the decentration of ICL and the tilt and the CDVA values was established. No postimplantation effect of ICL with a central hole on vision was established in myopia patients with primary iridociliary cysts, within certain limits of ICL decentration and tilt values.

Predicting Postoperative Anterior Chamber Angle for Phakic Intraocular Lens Implantation Using Preoperative Anterior Segment Metrics.

The anterior chamber angle (ACA) is a critical factor in posterior chamber phakic intraocular lens (EVO Implantable Collamer Lens [ICL]) implantation. Herein, we predicted postoperative ACAs to select the optimal ICL size to reduce narrow ACA-related complications. Regression models were constructed using pre-operative anterior segment optical coherence tomography metrics to predict postoperative ACAs, including trabecular-iris angles (TIAs) and scleral-spur angles (SSAs) at 500 µm and 750 µm from the scleral spur (TIA500, TIA750, SSA500, and SSA750). Data from three expert surgeons were assigned to the development (N = 430 eyes) and internal validation (N = 108 eyes) datasets. Additionally, data from a novice surgeon (N = 42 eyes) were used for external validation. Postoperative ACAs were highly predictable using the machine-learning (ML) technique (extreme gradient boosting regression [XGBoost]), with mean absolute errors (MAEs) of 4.42 degrees, 3.77 degrees, 5.25 degrees, and 4.30 degrees for TIA500, TIA750, SSA500, and SSA750, respectively, in internal validation. External validation also showed MAEs of 3.93 degrees, 3.86 degrees, 5.02 degrees, and 4.74 degrees for TIA500, TIA750, SSA500, and SSA750, respectively. Linear regression using the pre-operative anterior chamber depth, anterior chamber width, crystalline lens rise, TIA, and ICL size also exhibited good performance, with no significant difference compared with XGBoost in the validation sets. We developed linear regression and ML models to predict postoperative ACAs for ICL surgery anterior segment metrics. These will prevent surgeons from overlooking the risks associated with the narrowing of the ACA. Using the proposed algorithms, surgeons can consider the postoperative ACAs to increase surgical accuracy and safety.

Assessment of Risk Factors Affecting Refractive Outcomes after Phacovitrectomy for Epiretinal Membrane.

To investigate factors associated with refractive outcomes after phacovitrectomy for epiretinal membrane (ERM). Retrospective review of patients undergoing phacovitrectomy for ERM was done. The main outcome measure was predictive refraction error (PE), defined as observed refraction error - target refraction error, calculated by the SRK/T, Haigis, and SRK II formulae. PE was measured at postoperative 1, 3, and 6 months. Simple and multiple linear regression analysis were used to evaluate factors associated with PE. A total of 53 eyes of 53 patients were included. The mean PEs at postoperative 1, 3, and 6 months were all negative, implying myopic shift in all patients regardless of the intraocular lens formula used. Haigis formula showed the least myopic shift among the three formulae (p = 0.001, Friedman test). There was no significant difference in PE depending on preoperative central macular thickness (CMT) in subgroup analysis. On stepwise multiple linear regression analysis, ERM etiology (β = 0.759, p = 0.004, SRK/T formula; β = 0.733, p = 0.008, Haigis formula; β = 0.933, p &lt; 0.001, SRK II formula), preoperative anterior chamber depth (β = -0.662, p = 0.013, Haigis formula; β = -0.747, p = 0.003, SRK II formula), and decrease of CMT (β = -0.003, p = 0.025, SRK/T formula) were significantly associated with PE at postoperative 6 months. Myopic shift in PE was observed after combined phacovitrectomy for epiretinal membrane. ERM etiology, preoperative anterior chamber depth, and decrease of CMT were significantly associated with PE at postoperative 6 months. There was no difference in PE after surgery between the two groups defined by CMT (≥500 and &lt;500 μm).

Short-term clinic observation of misalignment and rotational stability after implantable collamer lens implantation.

We aimed to investigate misalignment (tilt and decentration) and rotational stability of the implantable collamer lens V4c 6months after implantation and to explore the potential risk factors associated with postoperative misalignment and rotation. A total of 36 eyes of 36 patients with high myopia and myopic astigmatism who underwent implantable collamer lens V4c implantation were included in this study. Tilt, decentration, and rotation of the implantable collamer lens were assessed postoperatively at l week, 1month, 3months, and 6months. Correlation analysis was used to identify the potential risk factors for implantable collamer lens tilt, decentration, and rotation at 6months postoperatively. Higher-order aberration was measured to evaluate the effect of implantable collamer lens misalignment on visual quality at pupil diameters of 4.0mm and 6.0mm. The tilt and decentration at the last follow-up were 2.43 ± 1.35° and 0.278 ± 0.160mm, respectively. There was a significant positive correlation between tilt and decentration (r = 0.31, P = 0.046). No significant correlation was detected between implantable collamer lens decentration and internal higher-order aberrations (P > 0.05). The degree of implantable collamer lens rotation (3.11 ± 2.00°) was significantly associated with the vault (r = - 0.422, P = 0.01), while it was positively associated with the preoperative anterior chamber depth (r = 0.36, P = 0.034). No significant correlation was found between postoperative astigmatism and rotation (r = - 0.07, P = 0.351). The implantable collamer lens V4c provides relatively stable misalignment and rotation after implantation. The ICL lens vault is a potential risk factor for postoperative implantable collamer lens rotation. The absolute value of decentration and tilt was relatively small, which showed no correlation with internal higher-order aberration in short-term observation.

Phacoemulsification Results of Eyes with Primary Angle Closure and Primary Angle Closure Glaucoma Using the Pentacam System

Aim: To evaluate the phacoemulsification results of patients with primary angle closure (PAC) and primary angle closure glaucoma (PACG) using the Pentacam system. Method: This retrospective cohort study included patients with PAC and PACG who underwent phacoemulsification and intraocular lens implantation between 2018 and 2021 in one tertiary center. Anterior chamber parameters measured using the Pentacam system and gonioscopic and intraocular pressure (IOP) changes were evaluated preoperatively and postoperatively. Results: Nineteen eyes of 13 patients with PAC and PACG were included in the study. The mean age of the patients was 63.2 years, and 30.8% were male. The mean preoperative and postoperative third-month IOP was 21.0 ± 7.4 mmHg (11-40) and 13.7± 2.5 mmHg (9-18), respectively (p &lt; 0.01). The mean preoperative anterior chamber angle (ACA) measured by the Pentacam system was 21.07 ± 4.16° (13-27). The mean preoperative anterior chamber depth (ACD) and the anterior chamber volume (ACV) measured by the Pentacam system were 1.79 ± 0.24 mm (1.39-2.22) and 72.55 ± 20.64 mm3 (45-109), respectively. The postoperative third-month topographic measurements were as follows: mean angle, 35.76 ± 7.32° (20.1-46.9); mean ACD, 3.52 ± 0.95 mm (1.15-4.46); and mean ACV, 133.21 ± 25.21 mm3 (81-173) (p &lt; 0.01). Conclusion: Pentacam is a useful system to evaluate anterior segment changes after phacoemulsification in patients with PAC and PACG. Phacoemulsification was found to result in significant IOP reduction in these patients.

Combination of Trabeculectomy and Primary Pars Plana Vitrectomy in the Successful Treatment of Angle-Closure Glaucoma with BEST1 Mutations: Self-Controlled Case Series.

This study aimed to illustrate the efficacy of the combination of lens extraction, trabeculectomy, and anterior vitrectomy in patients with secondary angle-closure glaucoma (ACG) with autosomal recessive bestrophinopathy or Best vitelliform macular dystrophy. This is a retrospective self-controlled case series study. Five patients undergoing a single trabeculectomy in one eye and triple surgery in the other eye were enrolled. All patients underwent a complete ophthalmic examination that included best-corrected visual acuity (BCVA), intraocular pressure (IOP), ultrasound biomicroscopy, and static gonioscopy. Multimodal fundus imaging was performed, including color fundus photography, fundus autofluorescence, and optical coherence tomography. Genetic testing was also analyzed. Among the 10 eyes, the mean IOP was 31.4 ± 4.7mmHg before surgery. The mean axial length (AL) was 21.53mm and the anterior chamber depth (ACD) was 2.31mm. There were no statistically significant differences in preoperative IOP, BCVA, ACD, and AL between the two groups (all P > 0.05). The mean follow-up time was 64.0months. All five eyes with a single trabeculectomy developed malignant glaucoma (MG). No complications were found in the other five eyes with triple surgery, and the anterior chamber was deepened and stable after surgery until the last visit. The mean IOP at the last visit was normalized to 16mmHg without using any medications. Triple surgery is superior to single trabeculectomy for patients with ACG and BEST1 mutation, effectively bypassing MG complications. The vitreous may play a vital role in the mechanism of ACG in those patients and the high incidence of MG after filtering surgery.

Efficacy and safety after posterior chamber Implantable Collamer Lens implantation according to preoperative anterior chamber depth: Short-term comparative study.

To compare visual, refractive, and safety outcomes of posterior chamber Implantable Collamer Lens (ICL) implantation for the correction of myopia according to the preoperative anterior chamber depth (ACD). Retrospective, comparative study, patients submitted to implantation of myopic posterior-chamber phakic Implantable Collamer Lens (ICL), model V4C/V5, minimum follow-up of 12 months; two groups were created: Group 1 (ACD 2.80 to 2.99 mm) and Group 2 (ACD equal to or greater than 3.00 mm). The parameters evaluated were uncorrected and corrected visual acuity, subjective refraction, efficacy and safety index, predictability, endothelial cell density, central vault, anterior chamber angle and postoperative complications. A total of 558 eyes from 298 patients were evaluated: 111 eyes (19.9%) in group 1 and 447 eyes (80.1%) in group 2. At 12 months, the efficacy index was similar in both groups (p = 0.264); the safety index was higher in group 1 (p = 0.031); the mean central Vault was significantly lower in group 1 (212.8 vs 410.6 μm; p < 0.001). Respectively, 93 (83.8%) and 366 (84.1%) eyes were within ±0.50 D of targeted refraction. Anterior chamber angle significantly decreased during follow-up in both groups (p < 0.001; p < 0.001). Intraocular pressure did not change significantly (p = 0.310 and p = 0.446, respectively). There were no significant differences in endothelial cell density loss (p = 0.278) or in the rate of complications observed (p = 0.733). ICL implantation is an effective and safe procedure in eyes with shallow anterior chambers, with visual and refractive results and complication rates identical to those obtained in deeper anterior chambers.

Machine learning predicting myopic regression after corneal refractive surgery using preoperative data and fundus photography.

Myopic regression after surgery is the most common long-term complication of refractive surgery, but it is difficult to identify myopic regression without long-term observation. This study aimed to develop machine learning models to identify high-risk patients for refractive regression based on preoperative data and fundus photography. This retrospective study assigned subjects to the training (n = 1606 eyes) and validation (n = 403 eyes) datasets with chronological data splitting. Machine learning models with ResNet50 (for image analysis) and XGBoost (for integration of all variables and fundus photography) were developed based on subjects who underwent corneal refractive surgery. The primary outcome was the predictive performance for the presence of myopic regression at 4years of follow-up examination postoperatively. By integrating all factors and fundus photography, the final combined machine learning model showed good performance to predict myopic regression of more than 0.5 D (area under the receiver operating characteristic curve [ROC-AUC], 0.753; 95% confidence interval [CI], 0.710-0.793). The performance of the final model was better than the single ResNet50 model only using fundus photography (ROC-AUC, 0.673; 95% CI, 0.627-0.716). The top-five most important input features were fundus photography, preoperative anterior chamber depth, planned ablation thickness, age, and preoperative central corneal thickness. Our machine learning algorithm provides an efficient strategy to identify high-risk patients with myopic regression without additional labor, cost, and time. Surgeons might benefit from preoperative risk assessment of myopic regression, patient counseling before surgery, and surgical option decisions.

Factors Related to Visual Outcomes after Lens Surgery in Isolated Microspherophakia.

Purpose To evaluate the main factors influencing visual performance after lens subluxation surgery in subjects with isolated MSP. Design Retrospective study. Methods In this study, 38 eyes of subjects with isolated MSP (microspherophakia) were included and divided into two groups based on preoperative IOP (intraocular pressure), IOP <21 mmHg, or IOP ≧21 mmHg. Phacoemulsification and scleral-fixated modified capsular tension ring implantation were performed with or without goniosynechialysis according to the IOP. Some ocular biometric parameters, such as corneal curvature, corneal pachymetry, endothelial cell count (ECC), anterior chamber depth (ACD), and axial length, were evaluated. The best-corrected visual acuity (BCVA) and IOP of these subjects were measured before the surgery and during <1 month and 3- to 6-month postoperative follow-ups. Results Compared with the high IOP group, the normal IOP group was significantly younger and had better preoperative BCVA, a higher ECC, deeper ACD, a lower postoperative IOP, and flatter total corneal refractive power K1. The multivariable analysis revealed that preoperative ACD (b = −0.113, t = −2.070, P=0.047) and preoperative BCVA (b = 0.153, t = 2.562, P=0.015) were significantly associated with postoperative BCVA at 3–6 months. A preoperative ACD of 1.86 mm was found to be the optimal cut-off point for 3- to 6-month postoperative BCVA of ≧20/63 (≤0.52 logMAR). Conclusions In addition to the effect of normal IOP, better preoperative BCVA and deeper ACD also correlated with better visual outcomes after lens surgery. Preoperative ACD served as a warning for isolated MSP subjects, especially for the risk of irreversible loss of postoperative vision. This trial is registered with “ChiCTR2000039132”.

Article Evaluation of the role of anterior chamber depth changes in determining refractive outcome after cataract surgery

In the present study the function of anterior chamber depth (ACD) changes in determining the refractive outcome after cataract surgery has been studied comprehensively. 210 successive adult patients going through unilateral cataract surgery (phacoemulsification by a single surgeon) were included in this prospective study. Depending on axial length patients were suitably classified into 3 groups: Group 1: &lt;22 xss=removed xss=removed&gt;26 mm (n = 70). Pre-operative and post-operative ACD were assessed on immersion ultrasound. The patients were arbitrarily reclassified into group A (≤1.7 mm) and B (&gt;1.7 mm) based on mean ACD change. Post-operative emmetropic, myopic, or hypermetropic status was also determined in all patients. Mean ACD change in short eyes (Group 1), normal (Group 2), and long (Group 3) eyes was 1.90 mm, 1.75 mm, and 1.45 mm, respectively. The Hyperopic shift was noted when the change in ACD was less than 1.70 mm and Myopic shift was noted when the alteration in anterior chamber depth was more than 1.70 mm. Short eyes were more prone to greater post-operative ACD changes as compared to long eyes. Assessment of pre-operative ACD and its subsequent changes after cataract surgery may help in predicting postoperative refractive error. The lesser amount of change in ACD may result in a hyperopic shift and a higher amount of change would result in a myopic shift. Keywords: Anterior chamber depth, Axial length, Myopia, Hypermetropia, Cataract surgery.

Keratometry, biometry, and prediction of intraocular lens power in adult tigers (Panthera tigris).

To calculate the necessary pseudophakic intraocular lens (IOL) power to approximate emmetropia in adult tigers. 17 clinically normal adult tigers. 33 eyes of 17 clinically normal adult tigers underwent routine ophthalmic examination and B-scan ultrasonography while anesthetized for unrelated procedures. Specific ultrasound data (globe measurements and corneal curvature) and estimated postoperative IOL positions were utilized to calculate predicted IOL power by use of Retzlaff and Binkhorst theoretical formulas. Applanation tonometry and refraction were also performed. Mean ± SD axial globe length was 29.36 ± 0.82 mm, preoperative anterior chamber depth was 7.00 ± 0.74 mm, and crystalline lens thickness was 8.72 ± 0.56 mm. Mean net refractive error (n = 33 eyes) was +0.27 ± 0.30 diopters (D). By use of the Retzlaff formula, mean predicted IOL power for the postoperative anterior chamber depth (PACD), PACD - 2 mm, and PACD + 2 mm was 43.72 ± 4.84 D, 37.62 ± 4.19 D, and 51.57 ± 5.72 D, respectively. By use of the Binkhorst equation, these values were 45.11 ± 4.91 D, 38.84 ± 4.25 D, and 53.18 ± 5.81 D, respectively. Mean intraocular pressure for all eyes was 14.7 ± 2.69 mm Hg. The calculated tiger IOL was lower than reported values for adult domestic felids. Further studies evaluating actual PACD and pseudophakic refraction would help determine the appropriate IOL power to achieve emmetropia in this species.