Postoperative Anterior Chamber Depth Research Articles

Impact of scleral tunnel length on the position of intraocular lenses in flanged intrascleral haptic fixation.

To investigate the effect of scleral tunnel length on the effective lens position and tilt of the intraocular lens (IOL) in flanged intrascleral haptic fixation (ISHF) using anterior segment optical coherence tomography (AS-OCT). Tertiary institution. Retrospective case-control study. This study included 55 and 42 eyes that underwent ISHF with 1.0 and 2.0 mm scleral tunnels, respectively. 23 eyes that underwent sutured fixation were used as a control. The anterior chamber depth (ACD), scleral tunnel length, incident angle of haptic, and tilting of optic were analyzed using AS-OCT. The mean postoperative ACD, vertical tilt angle, and spherical equivalent of the 1.0 mm were 5.27 ± 0.39 mm, 6.04 ± 4.87 degrees, and 0.38 ± 1.03 diopters, respectively. The ACD and vertical tilt angle of the 1.0 mm were larger than those of the others ( P < .001 and P < .05, respectively), and the postoperative spherical equivalent was more hyperopic ( P < .05). The 2.0 mm exhibited a lower frequency of tilting greater than 7 degrees. The intereye difference in ACD between in-the-bag fixation and ISHF of the 1.0 mm tunnel was significantly greater than that in the 2.0 mm tunnel ( P < .05). The 1.0 mm tunnel had a significantly larger incident angle and a longer tunnel length ( P < .001, respectively) and showed a greater difference in the tunnel length on both sides ( P < .05). A shorter tunnel yielded a more unstable IOL position, greater variation in angle and tunnel length, and longer ACD during ISHF. An exact 2.0 mm tunnel must be created on both sides to achieve a stable and predictable IOL position.

Association of refractive outcome with postoperative anterior chamber depth measured with 3 optical biometers.

This study evaluated the relationship between refractive outcomes and postoperative anterior chamber depth (ACD, measured from corneal epithelium to lens) measured by swept-source optical coherence tomography (SS-OCT), optical low-coherence reflectometry (OLCR), and Scheimpflug devices under the undilated pupil. Patients undergoing cataract phacoemulsification with intraocular lens (IOL) implantation in a hospital setting were enrolled. Postoperative ACD (postACD) was performed with an SS-OCT device, an OLCR device, and a Scheimpflug device at least 1month after cataract surgery. After adjusting the mean predicted error to 0, differences in refractive outcomes were calculated with the Olsen formula using actual postACD measured from 3 devices and predicted value. Overall, this comparative case study included 69 eyes of 69 patients, and postACD measurements were successfully taken using all 3 devices. The postACD measured with the SS-OCT, OLCR, and Scheimpflug devices was 4.59 ± 0.30, 4.50 ± 0.30, and 4.54 ± 0.32mm, respectively. Statistically significant differences in postACD were found among 3 devices (P < 0.001), with intraclass correlation coefficients (ICCs) and Bland-Altman showing good agreement. No significant difference in median absolute error was found with the Olsen formula using actual postACD obtained with 3 devices. Percentage prediction errors were within ± 0.50D in 65% (OLCR), 70% (Scheimpflug), and 67% (SS-OCT) calculated by actual postACD versus 64% by predicted value. Substantial agreement was found in postACD measurements obtained from the SS-OCT, OLCR, and Scheimpflug devices, with a trend toward comparable refractive outcomes in the Olsen formula. Meanwhile, postACD measurements may be potentially superior for the additional enhancement of refractive outcomes.

Anterior Segment Changes and Refractive Outcomes after Cataract Surgery Combined with Gonioscopy-Assisted Transluminal Trabeculotomy in Open-Angle Glaucoma

To compare the accuracy of intraocular lens (IOL) calculation formulas in patients undergoing phacoemulsification combined with gonioscopy-assisted transluminal trabeculotomy (phaco-GATT) and to determine the predictive factors for refractive errors. Fifty-three eyes of 53 patients undergoing phaco-GATT were retrospectively reviewed. The preoperative and postoperative 3-month anterior segment (AS) parameters were measured by Scheimpflug camera. The mean prediction error (PE), mean absolute error (MAE) in the Sanders-Retzlaff-Kraft/theoretical (SRK/T), Barrett- Universal II, Hill-radial basis function (Hill-RBF) and Kane formulas were compared. The influence of biometric parameters on PE were analyzed by correlation analysis. Postoperatively, there was a statistically significant decrease in axial length (AL) and significant enlargement in anterior chamber depth (ACD), anterior chamber angle (ACA), and anterior chamber volume (p<0.001). The mean PE using SRK/T (-0.08 diopters [D]) was more myopic than in the Barret (0.01 D) and Hill-RBF (0.01 D). The PE closest to zero was in the Kane formula (0.001 D). The Kane formula provided a lower MAE (0.30±0.28 D) than the SRK/T (0.38±0.32 D) and Barrett (0.36±0.30 D) (p<0.001). The MAE in Hill-RBF (0.32±0.28) was comparable with that in Kane (p=0.02). Preoperative AL was significantly associated with PE in all formulas except Kane. Barrett was the only formula that did not have a significant correlation between PE and postoperative ACD and ACA. The Kane formula may provide higher predictability of the IOL power calculation than the SRK/T and Barrett-Universal II formulas in phaco-GATT surgery, which can cause significant changes in the AS and AL.

Evaluation of Corneal Topography Changes Following Deep Anterior Lamellar Keratoplasty in Patients with Keratoconus

Background. The aim of this study is to evaluate the morphologic changes of the cornea and anterior chamber by using corneal topography (CT) in patients undergoing deep anterior lamellar keratoplasty (DALK) due to keratoconus. Patients and methods. This observational case-control study included total 53 eyes of 53 patients with keratoconus and underwent DALK surgery. All patients were evaluated preoperatively and 3 months after suture removal with CT. In CT, anterior chamber depth (ACD), iridocorneal angle (ICA), anterior chamber volume (ACV), central corneal thickness (CCT), maximum keratometric value (Kmax), flattest simulated meridian keratometry (SimK1), steepest simulated meridian keratometry (SimK2) and simulated keratometry average (SimKavg) results were compared before and after DALK surgery. Results. A significant increase was observed in CCT values after DALK surgery (p &lt; 0.001). Patients showed statistically significant decrease in Kmax, SimK1, SimK2 and SimKavg values (p &lt; 0.001 for all). Postoperative ACD and ACV values were significantly lower (p &lt; 0.001). The ICA values showed no significant difference (p = 0.183) between preoperative and postoperative values (49,95 ± 5,85 and 46,30 ± 11,33 respectively). Conclusion. We determined a dramatic decrease in keratometric values, ACD and ACV values and an increase of corneal thickness after DALK surgery. Although DALK can be performed without interfering with the anterior chamber, has a significant effect in anterior chamber.

Evaluation of the Effect of Scleral Buckling on Anterior Segment and Refractive Changes Using Anterior Segment Optical Coherence Tomography

ABSTRACT Purpose To evaluate the changes of anterior segment and refractive parameters after scleral buckling (SB) surgery for uncomplicated rhegmatogenous retinal detachment (RRD) using anterior segment optical coherence tomography (AS-OCT). Methods Thirty-six RRD eyes were consecutively enrolled. Analysis concerned the central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber volume (ACV), iris-trabecular contact (ITC), angel opening distance (AOD), angle recess area (ARA), trabecular-iris space area (TISA)，trabecular iris angle (TIA) and refractive parameters, including average keratometry (AvgK), cylindrical power (CYL), regular astigmatism, asymmetry and high order irregularity (HOI) at baseline and 1 day, 1 month, 2 months, 6 months and 12 months postoperatively. AS-OCT was performed at RRD diagnosis and day 1, week 1, month 1 and month 6 after SB to evaluate the scleral buckling. Results A statistically significant postoperative CCT increase, ACD and ACV decrease were observed at 1 day and 1 month postoperatively. ITC analysis showed that the angle of the entire circumference narrowed at 1 month postoperatively. There was a significant decrease in all the angle parameters (AOD500/750, ARA500/750, TISA500/750, and ARA500/750) at 1 day and 1 month after SB surgery. However, all of the above parameters returned to the preoperative level at 12 months. Refractive parameters including AvgK, regular astigmatism, CYL, asymmetry, and HOI of anterior corneal surface and total corneal increased on the 1 day and 1 month after SB surgery and persisted even after 12 months follow-up. However, there was no significant difference in refractive parameters of posterior corneal surface during follow-up. Conclusion The changes in the structure of anterior segments after SB surgery were almost returned to the preoperative levels at 12 months postoperatively. However, SB surgery has a long-term effect on refractive parameters throughout a 12-month follow-up.

Changes in anterior chamber biometry and intraocular pressure after uneventful phacoemulsification in non-glaucomatous eyes.

In non-glaucomatous eyes, many factors impact intraocular pressure (IOP) reduction following phacoemulsification. This study aimed to determine the relationship between changes in IOP and alterations in anterior chamber biometric measurements using the Pentacam Scheimpflug anterior segment imaging system before and after uneventful phacoemulsification in non-glaucomatous eyes. This prospective interventional study included patients with ages of 20 - 80 years, no known systemic diseases, and visually significant cataracts necessitating phacoemulsification with posterior chamber intraocular lens implantation. The preoperative and two-month postoperative IOPs were measured using a Goldmann applanation tonometer, and the iridocorneal angle (ICA) in four quadrants (superior, inferior, nasal, and temporal), anterior chamber depth (ACD), and anterior chamber volume (ACV) were measured using the Pentacam. Forty-two eyes of 42 patients with a mean (standard deviation [SD]) age of 56.8 (10.7) years were included; 22 (52%) were men and 20 (48%) were women. The eyes demonstrated statistically significant changes in postoperative IOP, ACD, ACV, and in widening of the ICA (all P < 0.05), with a mean (SD) IOP reduction of 4.5 (2.7) mmHg, ACD deepening of 0.7 (0.6) mm, ACV increase of 33.2 (21.1) mm3, and ICA widening of 7.5o (6.4o), 12.4o (7.7o), 9.1o (7.1o), and 11.5o (6.1o) in the superior, inferior, temporal, and nasal quadrants, respectively. A significant positive correlation was detected between pre- and postoperative IOP (r = + 0.58; P < 0.001) and between pre- and postoperative ACD (r = + 0.50; P < 0.001). Significant negative correlations were detected between preoperative ACV and changes in ACV (r = - 0.42; P < 0.001) and between preoperative ICA and changes in ICA (r = - 0.02; P = 0.001). However, no significant correlations were observed between the changes in IOP and patient age (r = + 0.001; P = 0.957) and axial length of the eye (r = + 0.13; P = 0.221), or changes in ICA (r = - 0.01; P = 0.945), ACD (r = + 0.01; P = 0.945), and ACV (r = - 0.12; P = 0.599). We observed a significant reduction in IOP, widening of the ICA, and increases in ACD and ACV after phacoemulsification; however, there was no significant correlation between changes in IOP and other biometric variables. Further studies are required to determine the exact mechanisms underlying these effects.

Relationship between Postoperative Anterior Chamber Depth and Refraction Based on the Haptic Fix Position in Intraocular Lens Intrascleral Fixation

The aim of this study was to analyze the refraction and iris capture tendency regarding the fixation position with respect to the intrascleral fixation (ISF) of intraocular lenses. Consecutive patients who underwent ISF 1.5 mm (ISF 1.5, 45 eyes) and 2.0 mm (ISF 2.0, 55 eyes) from the corneal limbus with NX60, as well as those who underwent normal phacoemulsification with in-the-bag ZCB00V (ZCB, 50 eyes), were enrolled. The anterior chamber depth (post-op ACD), the estimated ACD when using the SRK/T (post-op ACD-predicted ACD), and the refractive error (post-op MRSE, and the predicted MRSE) were all calculated. In addition, the postoperative iris capture was also investigated. The post-op MRSE-predicted MRSE values were: -0.59, 0.02, and 0.00 D (ISF 1.5, ISF 2.0, and ZCB) (p < 0.05, between ISF 1.5 vs. ISF 2.0 and ZCB); the post-op ACD values were: 4.00, 4.17, and 4.29 mm (p < 0.05, ISF 1.5 vs. ZCB); and the post-op ACD-predicted ACD values were: -2.03, -1.98, and -1.60 mm (p < 0.05, between ZCB vs. ISF 1.5 and ISF 2.0). The iris capture occurred in four eyes with regard to ISF 1.5 and three eyes with ISF 2.0 (p = 0.52). Moreover, ISF 2.0 possessed 0.6D hyperopia and 0.17 mm deeper anterior chamber depth. The refractive error of ISF 2.0 was less than that of ISF 1.5. Lastly, no significant iris capture onset was noted between ISF 1.5 mm and 2.0 mm.

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.

Safety of intraocular pressure measurement using air-puff tonometer after implantable collamer lens implantation

To determine the safety of intraocular pressure (IOP) measurement using a noncontact tonometer in patients who have undergone implantable collamer lens (ICL) implantation. Eye, Ear, Nose, and Throat Hospital. Prospective study. 64 eyes of 33 patients (aged 28.4 ± 5.2 years) scheduled for ICL implantation were enrolled. The anterior segment parameters and vault were obtained using an anterior segment analyzer. A noncontact air-puff tonometer was used preoperatively and at 1 day and 1 week postoperatively to assess corneal biomechanical properties and IOP. The Corvis ST was used to evaluate the distance between the corneal endothelial layer and iris (E-Iris Dist) and the distance between the corneal endothelial layer and ICL (E-ICL Dist) when the cornea was deformed by the airflow. The mean anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA) decreased significantly postoperatively (all P values <.001). The E-ICL Dist values measured 1 day and 1 week postoperatively were similar ( P = .107). However, a contact between the corneal endothelium and ICL was detected in 2 eyes when the cornea was deformed to the highest concavity. The 1-day postoperative vault, ACV, ACA, and preoperative stress-strain index contributed significantly ( P = .001, P = .023, P = .010, and P = .019, respectively) to determine the distance. The mean E-iris Dist values decreased significantly at 1 day and 1 week postoperatively ( P < .001). The 1-week postoperative vault and ACD contributed significantly ( P = .025 and P = .039, respectively) to determine the E-Iris Dist value. Excessively high vault, shallow ACD, narrow ACA, low ACV, and soft cornea are associated with a lower E-ICL distance and thus may be risk factors for a contact between the corneal endothelium and ICL during IOP measurement. Although there is no proof that the contact may cause any risks to the endothelium, noncontact air-puff tonometry should be avoided in eyes predicted by the study model to be at risk of this occurring. Contact IOP measurements using Goldmann applanation tonometers or dynamic contour tonometers may be alternate methods of IOP measurements in extreme cases.

Influence of combined phacovitrectomy without tamponade on intraocular lens displacement and postoperative refraction.

To compare phacoemulsification versus phacovitrectomy regarding postoperative intraocular lens (IOL) shift and refraction. This prospective bilateral comparison study included 40 eyes of 20 patients. Inclusion criteria were combined phacovitrectomy without gas/air tamponade in one eye and cataract surgery in the contralateral eye with implantation of the same IOL. Postoperative anterior chamber depth (ACD) was compared between both groups 1-5 hr, 1 day and 8 weeks after surgery. Postoperative refraction was compared after 8 weeks using the Holladay I, HofferQ, SRK/T, Haigis and Barrett formulae. There were no intergroup differences in ACD (8 weeks: 0.02 mm absolute difference, SD 0.22, range -0.36 to 0.65, p = 0.401), mean absolute refractive error (8 weeks: Holladay I p = 0.452; HofferQ p = 0.475; SRK/T p = 0.498; Haigis p = 0.869; and Barrett p = 0.352) or percentages within the 0.5 D and 1.0 D range at any time-point. All formulae were optimized for the phacovitrectomy and the cataract groups. There was no correlation of macular thickness change and refractive error (cataract group r2 = -0.13, p = 0.58; phacovitrectomy group r2 = -0.10, p = 0.68). Combined phacovitrectomy without air/ gas tamponade caused neither ACD displacement nor refractive shifts compared to phacoemulsification alone. Surgically induced macular thickness change had no significant influence on postoperative refraction in this study. All five IOL formulae showed comparable postoperative refractive outcomes.

Modified Trabeculectomy versus Glaucoma Drainage Implant Surgery: A Retrospective Comparative Study for Refractory Glaucoma Treatment.

Purpose To observe and compare the efficacy of modified trabeculectomy (TE), Ahmed drainage valve implantation (AGV), and EX-PRESS glaucoma shunt for refractory glaucoma (RG). Methods The study population of this retrospective study comprised 73 patients (76 eyes) who were suffering from RG and treated with modified TE, AGV, and EX-PRESS glaucoma shunt in our hospital from October 2012 to October 2020. The number of cases who underwent modified TE, AVG, and EX-PRESS glaucoma shunt was 36 (38 eyes). 19 (20 eyes), and 18 patients (18 eyes), respectively. The intraocular pressure (IOP), best-corrected visual acuity (BCVA), postoperative antiglaucoma medications, filter bubble morphology, anterior chamber depth (ACD), successful rate, and postoperative complications were recorded and statistically analyzed preoperative and 1 d, 1 w, 1 mon, 3 mon, 6 mon, and the end follow-up after operation. Results The BCVA differed insignificantly among the three cohorts before and 6 months after surgery. Compared to preoperative BCVA, the postoperative BCVA of the three groups had no statistical significance. An obvious reduction in IOP was observed in all the three group after operation (P < 0.05). An obvious decrease in antiglaucoma medications was observed after surgery in all the three groups (P < 0.05). The AGV group showed deeper ACD postoperatively, while no marked difference was found in postoperative ACD in the other two groups. The total success rates in modified TE and AGV groups were slightly higher than those in the EX-PRESS group. The three groups differed insignificantly in filter bubble morphology after operation. Conclusion Modified TE, AGV, and EX-PRESS glaucoma shunt showed equivalent efficacy for RG, which could validly reduce IOP and postoperative antiglaucoma medications. However, the success rates of modified TE and AGV were slightly higher than those of EX-PRESS glaucoma shunt in the last follow-up, and their complications were slightly less than those of the EX-PRESS glaucoma shunt.

Prediction of the trabecular iris angle after posterior chamber phakic intraocular lens implantation.

To create an equation for predicting the trabecular iris angle (TIA) and to verify its accuracy after implantable collamer lens (ICL) implantation. Nagoya Eye Clinic, Nagoya, Japan. Retrospective evaluation of a screening approach. 174 eyes (174 patients) that underwent ICL implantation were included. Patients were randomly assigned to the prediction equation group (116 eyes) or verification group (58 eyes). Anterior segment optical coherence tomography (AS-OCT) (CASIA2 TOMEY) was performed before and 3 months after ICL surgery. For the prediction group, a prediction equation was created with the preoperative AS-OCT parameters and ICL size as independent variables and the postoperative anterior chamber depth (ACD) as the dependent variable. Then, by applying the predicted post-ACD and preoperative AS-OCT parameters as independent variables and TIA after ICL surgery as the dependent variable, a prediction equation was created to predict the postoperative TIA (post-TIA) after ICL surgery. Each prediction equation was created using stepwise multiple regression analysis, and its accuracy was verified by a Bland-Altman plot in the verification group. The explanatory variables (standardized partial regression coefficient) selected in the post-TIA prediction equation were post-ACD (0.629), TIA750 (0.563), iris curvature (0.353), pupil diameter (-0.281), iris area (-0.249), and trabecular iris space area 250 (-0.171) (R2 = 0.646) (n = 116). There were no clinically significant systematic errors between measured and predictive post-TIA values in the verification group (n = 58). The mean absolute prediction error was 3.43 ± 2.22 degrees. Post-TIA was accurately predicted from the predicted post-ACD and other preoperative AS-OCT parameters.

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.

Refractive error induced by intraocular lens tilt after intrascleral intraocular lens fixation.

To investigate the spherical shift of intraocular lens (IOL) tilt after intrascleral fixation. We retrospectively reviewed the medical records of patients who underwent flanged intrascleral IOL fixation with transconjunctival 25- or 27-gauge pars plana vitrectomy at the Department of Ophthalmology of the Jikei University Hospital. The minimum follow-up duration was 3months. Second-generation anterior segment optical coherence tomography (CASIA2; TOMEY) was used to obtain the values of tilt and decentration of the intrasclerally fixated IOL and postoperative anterior chamber depth. We investigated the relationship between refractive error and various parameters, such as IOL tilt and decentration, axial length, and keratometry. In addition to our clinical investigation, we conducted optical simulations using Zemax to evaluate the spherical shift of the IOL tilt by means of the through-focus response and change in spherical equivalent power. The study involved 72 eyes of 67 patients. The degree of IOL tilt was correlated with the amount of refractive error (Spearman's rank correlation coefficient [CC] = - 0.32; P = 0.006). In particular, a tilt angle greater than 10° strongly affected the refractive error. The postoperative anterior chamber depth also correlated with the refractive error (CC = 0.50; P < 0.001), as opposed to decentration (CC = - 0.17; P = 0.15), axial length (CC = - 0.08; P = 0.49), and keratometry (CC = - 0.06; P = 0.64). Optical simulations also revealed a myopic shift that exponentially increased as the tilt became greater. IOL tilts that are greater than 10° induce refractive error.

Three-dimensional topographic changes of anterior chamber depth following phacoemulsification with intraocular lens implantation in cataract patients

To investigate the three-dimensional topographic changes of anterior chamber depth (ACD) following cataract surgery. Seventy-eight eyes with age-related cataract undergoing phacoemulsification and intraocular lens (IOL) implantation were retrospectively enrolled. Participants were evaluated with Pentacam for ACD topography before and approximately four weeks after the surgery. The absolute changes of ACD (AACD) and the relative changes of ACD (RACD) topography were calculated, and three-dimensional topographic contours were plotted. The influence of age, gender, distance to corneal apex (DCA), temporal-nasal and superior-inferior on AACD and RACD was analyzed. Both AACD and RACD were negatively correlated with the DCA (p < 0.001; p < 0.001) and positively correlated with the age at all DCA (p < 0.05 for all the analyses). Significantly greater AACD and RACD were observed in female subjects (p < 0.05, respectively, at all DCA). AACD was significantly larger in the temporal compared with the nasal region (p < 0.001) and at the superior compared with the inferior region (p < 0.001), but not RACD. Subgroup analysis indicated that the significant difference of the AACD between the temporal and nasal regions was manifested at the DCA of more than 6mm (p < 0.001), and the difference between the superior and inferior regions was observed at 2mm DCA for both AACD (p < 0.001) and RACD (p = 0.001). We depicted the topographic changes of ACD following cataract surgery and found that it was significantly influenced by age, gender, DCA and quadrant location. The research provided the basis for including postoperative ACD topography prediction before cataract surgery in the future.

On refraction shift after trabeculectomy

To determine the factors affecting the shift of refraction after trabeculectomy. The study included 42 patients who were examined prior to trabeculectomy and at the following timepoints: 1 week, 1 month and 3 months after surgery. Examination included tonometry with assessment of corneal biomechanical properties, keratorefractometry with vector analysis, and biometry. The obtained data was processed for regression analysis and to find the possible correlations. All significant correlations between the measured parameters only occur on week 1. Postoperative spherical component of refraction (sphere) correlates negatively both with preoperative axial length (AL) and anterior chamber depth (ACD) (r=-0.699 and r=-0.458, p<0.05) and postoperative AL and ACD (r= -0.767 and r= -0.415, p<0.011). Dependence of sphere on AL is also expressed as a regression model. The magnitude of AL change depends on the magnitude of intraocular pressure (IOP) change (r=0.729, p<0.0001) and correlates negatively with postoperative IOP (r=-0.454, p=0.009) and baseline corneal hysteresis (CH; r= -0.482, p=0.009). Dependence of AL on IOP is also expressed as a regression model. The magnitudes of sphere and cylinder shifts correlate negatively with each other (r=-0.416, p=0.038). Keratometry reveals that the overall cylinder value correlates with the corneal cylinder, and so do the magnitudes of their shifts (r=0.589 and r=0.574, p<0.0001). Dependence of corneal hysteresis on IOP is expressed as a regression model; however, neither tonometric nor biomechanical corneal properties correlate with refraction. Sphere correlates negatively with AL and ACD. In turn, AL is related to the reduction in IOP. This dependence is likely the most important one for the refraction shift after trabeculectomy. No correlations were found for the change of astigmatism.

Effect of Implantable Collamer Lens on Anterior Segment Measurement and Intraocular Lens Power Calculation Based on IOLMaster 700 and Sirius.

Purpose To investigate the possible effect of an implantable collamer lens (ICL) on ocular biometrics and intraocular lens (IOL) power calculation. Methods Ocular measurements were taken preoperatively and at the two-month follow-up using IOLMaster 700 and Sirius in 85 eyes (43 patients) who had previously undergone ICL surgery. IOL power was calculated using either IOLMaster 700 (Barrett Universal II formula) or Sirius (ray-tracing). All data were compared using the paired t-test. Results The difference between preoperative and postoperative anterior chamber depth (ACD), lens thickness (LT), and keratometry on the steep axis (K2) measured by IOLMaster 700 was statistically significant (p < 0.001). In 11 of 85 eyes, IOLMaster misjudged the anterior surface of the ICL as that of the lens, leading to an error in ACD and LT. There were no significant differences between preoperative and postoperative axial length (AL) (p = 0.223), white to white (WTW) (p = 0.100), keratometry on flat axis (K1) (p = 0.117), or central corneal thickness (CCT) (p = 0.648), measured using IOLMaster. The difference in IOL power calculated using the Barrett II formula was significant (p = 0.013). Regression analysis showed that AL and K had the greatest influence on IOL calculation (p < 0.001), and ACD and LT had less influence (p = 0.002, p = 0.218, respectively). K1 and K2 were modified to exclude the influence of K2, and modified IOLs showed no difference between pre and postoperation (p = 0.372). Preoperative and postoperative ACD measured using Sirius were significantly different (p < 0.001); however, the IOL power calculated using ray-tracing technology showed no significant differences (p > 0.05). Conclusions The ocular biometric apparatus may misjudge the anterior surface of the lens, resulting in measurement errors of ACD and LT, which has little effect on the calculation of IOL power when using IOLMaster 700 (Barrett Universal II formula) and Sirius (ray-tracing).

Ray tracing intraocular lens calculation performance improved by AI-powered postoperative lens position prediction

AimsTo assess whether incorporating a machine learning (ML) method for accurate prediction of postoperative anterior chamber depth (ACD) improves cataract surgery refraction prediction performance of a commonly used ray tracing...

IOP change after phacoemulsification with PCIOL implantation and its association with ocular biometric parameters

: To assess the impact on intraocular pressure (IOP) after Phacoemulsification (PE) with Posterior Chamber Intraocular Lens (PCIOL) implantation and its relation with ocular biometric parameters. The study was a prospective observational study included 524 eyes with normal IOP (11-21 mmHg) who underwent uneventful Phacoemulsification with PCIOL Implantation surgery for age-related cataract. IOP, Central Corneal Thickness (CCT), Anterior Chamber Depth (ACD), Axial Length (AL) were measured pre-operatively and one month post-operatively by Goldman Applanation Tonometer, Corneal Pachymeter and Optical Coherence Biometer, respectively. The post-operative IOP change and its relation with preoperative biometric parameters were determined.: The mean pre-operative and post-operative IOP was 13.44±1.98 &amp; 11.54±1.66mmHg, respectively, with an average IOP reduction after one month of 1.90±0.61mmHg. The mean pre-operative and post-operative ACD was 3.27±0.24 and 3.66±0.27 mm, respectively, with an average increase of 0.39 ±0.3 mm. Paired t-test showed post-operative IOP reduction was significantly associated with preoperative IOP (p&amp;#60;0.001) and ACD (p&amp;#60;0.001). But CCT and AL were not significantly associated. The linear regression analysis confirmed the proportional reduction of post-operative IOP, r 0.921. So 92.1% of the preoperative IOP is proportional to post-operative IOP reduction. The graphical representation shows more the pre-operative IOP, more the post-operative IOP reduction.: IOP is significantly reduced, and ACD increased after PE with PCIOL implantation surgery and is associated with post-operative IOP reduction. The post-operative IOP reduction is proportional to pre-operative IOP, and more the preoperative IOP, more the post-operative IOP reduction.