Postoperative Keratometry Research Articles

Manual Sutureless (MSICS) Cataract Surgery and Corneal Astigmatism

The most frequent preventable cause of blindness worldwide is cataracts. Manual Small Incision Cataract Surgery (MSICS) is still very much in use, even though cataract surgery is always changing. The resurgence of MSICS can be attributed to its low cost and safety, as it primarily uses easily sterilizable equipments and does not require sophisticated technology. This study aims to assess corneal astigmatism and manual sutureless (MSICS) cataract surgery after a month of follow-up. Forty individuals with cataract diagnoses were enrolled in this prospective study. During the procedure, a posterior chamber intraocular lens (IOL) implantation was done in addition to a superior manual minor incision under local anesthesia. The findings indicated that 15% or so of the patients experienced astigmatism following surgery. Also the findings revealed that sphere and cylinder refraction was significantly influenced by surgery. The means of sphere refraction before and after surgery were 3.93±6.37 and 0.93±0.98 D, while the corresponding means for cylinder refraction were 1.37±1.08 and 1.94±1.18 D. The results showed that means preoperative and postoperative Keratometry of cornea (K1) were 43.09±1.21 and 43.37±1.42 mm, while the corresponding means of Keratometry (K2) were 43.97±1.35 and 44.49±1.59 mm. The study concluded that the length of the superior incision (6.0 mm) may have contributed to the higher mean SIA than reported in other studies. However, more research is required to determine the impact of incision size on surgically produced astigmatism.

Conventional Epithelial-Off Corneal Crosslinking in Patients With Progressive Keratoconus: 10-Year Outcomes.

Corneal crosslinking (CXL) is the standard treatment of progressive keratoconus (KC). We evaluated the safety and 10-year outcomes of conventional "epithelial-off" CXL for progressive KC for the first time in a cohort in France. We conducted a retrospective review of patients undergoing conventional CXL (Dresden protocol) in our tertiary ophthalmology department from 2006 to 2011 with 10-year follow-up. The primary outcome was change in preoperative versus postoperative keratometry measured by maximum keratometry (Kmax), steep keratometry (K2), flat keratometry (K1), mean keratometry (Km), and topographic cylinder. Secondary outcomes were changes in visual and refractive outcomes. We report postoperative complications and adverse events. Eighty-nine eyes from 76 patients (67% male patients, mean age 22.7 ± 7.6 years) were included. Mean Kmax (-2.31 ± 2.98 diopters (D); P < 0.00001), K2 (-2.07 ± 3.15 D; P < 0.00001), K1 (-1.00 ± 2.29 D; P = 0.00008), Km (-1.53 ± 2.47 D; P < 0.00001), and topographic cylinder (-1.15 ± 2.53 D; P = 0.00004) significantly decreased 10 years after CXL compared with preoperative baseline. Significant decreases were still observed between 5 and 10 years after for mean Kmax, mean K2, mean K1, and mean Km. Mean distance best spectacle-corrected visual acuity and mean manifest refraction spherical equivalent were significantly improved after 10 years versus before CXL. The 10-year rate of repeat CXL was n = 3/76 patients (4%) (all younger than 18 years at first CXL) and of loss of >3 lines in best spectacle-corrected visual acuity was n = 1/76 patients (1%). Progressive KC was effectively stabilized with a prolonged flattening and maintenance of functional vision improvements after 10 years. Repeat CXL was rare and only required among younger patients.

THE EFFECT OF LIMBAL RELAXING INCISIONS ON 1-WEEK POSTOPERATIVE IN K1 AND K2 VALUES

Introduction: Limbal Relaxing Incisions (LRI) is a surgical technique used to correct astigmatism during cataract surgery. This technique used to reduce the steepness of the corneal curvature in a particular meridian. LRI can be performed alone or in combination with phacoemulsification. Methods: This prospective study aimed to investigate the effect of Limbal Relaxing Incisions (LRI) on corneal astigmatism in patients who underwent phacoemulsification cataract surgery. Five patients were included in this study, and preoperative and 1-week postoperative keratometry values (K1=flat keratometry and K2=steep keratometry) were measured using the IOL Master. Paired t-test analysis was used to compare the changes in K1 and K2 values before and after LRI. Results: Five patients with the mean age 39.8 years (range: 22 to 76 years) and corneal astigmatism 3.12 D (range: 2.25 to 4.66 D) were underwent LRI and cataract surgery. The mean preoperative K1 and K2 values were 42.12 D and 46.44 D, respectively, while the mean 1-week postoperative K1 and K2 values were 42.60 D and 45.80 D, respectively. Paired t-test analysis showed a statistically significant decrease in K2 values (p = 0.025) but no significant change in K1 values (p = 0.329). Conclusion: This study showed there were no significant difference between pre and postoperative of K1 and showed a significant decrease in K2 on IOL Master examination. The wide age range of the included patients may have influenced the effectiveness of LRI in reducing astigmatism. Further study with more subjects are required.

The Effect of Limbal Relaxing Incisions on 1-Week Postoperative K1 and K2 Values

Abstract&#x0D; Introduction &amp; Objectives : Limbal Relaxing Incisions (LRI) is a surgical technique used to correct astigmatism during cataract surgery. This technique used to reduce the steepness of the corneal curvature in a particular meridian. LRI can be performed alone or in combination with phacoemulsification.&#x0D; Methods : This prospective study aimed to investigate the effect of Limbal Relaxing Incisions (LRI) on corneal astigmatism in patients who underwent phacoemulsification cataract surgery. Five patients were included in this study, and preoperative and 1-week postoperative keratometry values (K1 and K2) were measured using the IOL Master. Paired t-test analysis was used to compare the changes in K1 and K2 values before and after LRI&#x0D; Results : Five eyes of Five patients with the mean age 39.8 years (range : 22 to 76 years) and corneal astigmatism 3.12 D (range : 2.25 to 4.66 D) were underwent LRI and cataract surgery. The mean preoperative K1 and K2 values were 42.12 D and 46.44 D, respectively, while the mean 1-week postoperative K1 and K2 values were 42.60 D and 45.80 D, respectively. Paired t-test analysis showed a statistically significant decrease in K2 values (p = 0.025) but no significant change in K1 values (p = 0.329).&#x0D; Conclusion : This study showed there were no significant difference between pre and postoperative of K1 and showed a significant decrease in K2 on IOL Master examination. The wide age range of the included patients, may have influenced the effectiveness of LRI in reducing astigmatism. Further study with more subject are required.

Peripheral hypertrophic subepithelial degeneration – case report

Purpose: The aim of the paper is to present the case of a 53-year-old female patient who, based on the clinical picture and optical coherent tomography of the anterior segment (AS-OCT), was diagnosed with peripheral hypertrophic subepithelial degeneration (PHSD) and underwent surgical treatment in the form of superficial keratectomy with mechanical removal of degenerative plaques.&#x0D; Methods: Analysis of AS-OCT images and corneal tomography based on Scheimpflug images and surgical treatment – superficial keratectomy with mechanical removal of degenerative plaques.&#x0D; Results: Before treatment, the best corrected visual acuity (BCVA) for distance, as assessed by the Snellen chart, was 3/50 c.cor +10.50/-6.50 ax 18° in the right eye (RE) and in the left eye (LE) 5/10 c.cor +10.75/-3.00 ax 48°. Preoperative keratometry performed with the Pentacam device was K1 32.7 D and K2 46.0 D in the OP and K1 42.5 D and K2 44.7 D in the LE. Postoperative BCVA in RE was 5/8 c.cor +3.50/-1.00 ax 120° at 5 months of follow-up and in LE 5/6 c.cor +4.75/-1.00 ax 64° at 3rd month of observation. Postoperative keratometry (Pentacam) in RE K1 was 44.6 D, K2 46.9 D in the 5th month of observation, and in LE K1 45.6 D, K2 46.5 D in the 3rd month of observation. As a result of the treatment, BCVA improved, astigmatism decreased and corneal translucency improved.&#x0D; Conclusions: AS-OCT and Scheimpflug-based corneal tomography are helpful in the diagnosis of PHSD. Superficial keratectomy with mechanical removal of degenerative plaques seems to be an effective treatment for PHSD

Deep Anterior Lamellar Keratoplasty-Treated Keratoconic Eyes With Descemet Membrane Rupture.

The aim of this study was to evaluate the outcomes of deep anterior lamellar keratoplasty (DALK) and compare it with penetrating keratoplasty (PKP) in keratoconic eyes with Descemet membrane (DM) rupture. In this comparative retrospective case series, 33 keratoconic eyes with a history of hydrops underwent DALK and 27 received PKP. Baseline and postoperative visual acuity, corneal astigmatism, mean keratometry, endothelial cell density, and complication rates were measured. The median follow-up of patients who underwent DALK was 45 months (range, 4-76 months) and that of patients who underwent PKP was 84 months (range, 4-136 months). Both procedures had comparable postoperative visual acuity, astigmatism, and mean keratometry. Significantly higher endothelial cell densities were observed in DALK than in PKP at 2, 3, and 5 years postsurgery (2043 ± 767 vs. 1165 ± 683 cell/mm 2 , P = 0.007, n = 12 in both groups at 2 years). Intra-DALK, 15 perforations occurred (44.12%) and 1 (2.94%) was converted to PKP. Graft rejection was diagnosed in 1 (3.03%) DALK procedure versus 8 (29.63%) PKP ( P = 0.008), and other long-term complication rates were equivalent. Kaplan-Meier survival analysis also revealed a higher rejection-free survival rate for the DALK group ( P = 0.012). Subgroup analysis within both groups based on the severity of preoperative DM rupture revealed no significant difference in any major 2-year outcomes. DALK showed similar beneficial visual outcome and safety but significantly better endothelial protection over PKP in eyes with keratoconus and previous hydrops. Therefore, DALK is recommended in posthydrops cases irrespective of the DM rupture severity.

Corneal remodeling after SMILE for moderate and high myopia: short-term assessment of spatial changes in corneal volume and thickness

PurposeTo evaluate the early corneal remodeling and its influencing factors after Small incision lenticule extraction (SMILE) for moderate and high myopia.MethodsThis was a retrospective study. Pre- and post-operative (1 week and 1, 3, 6 months) corneal volume (CV), mean keratometry (Km), and corneal thickness (CT) were measured by Scheimpflug tomography. CT at the central, thinnest point, and on concentric circles of 2, 4, and 6 mm diameter was recorded to assess corneal thickness spatial profile (CTSP) and percentage of thickness increase (PTI) in the moderate and high myopia groups, and to explore possible influencing factors.ResultsAfter SMILE, the peripheral CT decreased in the moderate myopia group and central corneal thickness (CCT) increased in the high myopia group at 1 month compared to 1 week (all P < 0.05). The CV, Km and CT were significantly increased at 3 months compared to 1 month (all P < 0.05), but there was no significant change at 6 months compared to 3 months for both groups (all P > 0.05). Patients with high myopia showed greater corneal thickness changes (△CT) and higher PTI than moderate myopia (all P < 0.05). Regression analysis revealed that in addition to refraction, peripheral PTI was negatively correlated with CCT in the moderate myopia group (4 mm: β = -0.023, P = 0.001; 6 mm: β = -0.050, P < 0.001), as well as in the high myopia group (4 mm: β = -0.038, P < 0.001; 6 mm: β = -0.094, P < 0.001). Moreover, peripheral PTI in the moderate myopia group was negatively correlated with age (4 mm: β = -0.071, P = 0.003; 6 mm: β = -0.162, P < 0.001).ConclusionsAfter SMILE, the CV, Km, and CTSP showed dynamic changes in the early stage, which stabilized after 3 months. Compared to the moderate myopia group, the high myopia group experienced slower corneal stabilization. The change in PTI at 6 months after SMILE may be related to higher preoperative refraction, thinner CCT and younger age.

Comparison of Surgically Induced Astigmatism between Superior and Supero-Temporal Incisions in Manual Small Incision Cataract Surgery

Objective: To compare visual outcomes and differences in surgically induced astigmatism between superior and supero temporal incisions in manual small incision cataract surgery (MSICS).&#x0D; Study Design: Quasi-experimental study.&#x0D; Place and Duration of Study: Combined Military Hospital, Rawalakot Pakistan, from Jan to Jun 2017.&#x0D; Methodology: Sixty patients were selected and divided into two groups of 30 patients each. One Group was given a superior incision, the other was made the supero-temporal incision, and Manual small incision cataract surgery was performed.Preoperative and postoperative visual acuity, keratometry and refractive data were collected for all patients. In addition,surgically induced astigmatism (SIA) was analysed using a line SIA calculator.&#x0D; Results: The mean age of our patients was 59.57±10.13 years. Post-operatively, the visual acuity significantly improved in both groups. Mean induced astigmatism due to surgery came out to be 0.75±0.44 D for the superior incision and 0.45±0.18 D for the supero- temporal incision. The study found that in the Superior Incision-Group, induced astigmatism was slightly higher than in the Supero-Temporal-Group. Moreover, the Supero-Temporal-Group had a better uncorrected visual outcome than the Superior Incision-Group.&#x0D; Conclusion: Overall, manual small incision cataract surgery has good visual outcomes. Manual small incision cataract surgery through supero-temporal incision was found to have a better visual outcome with less surgically induced astigmatism than the superior incision.

Comparative analysis of corneal versus scleral tunnel incision implantation of anterior artisan Aphakia intraocular lens

AbstractPurpose: To evaluate the surgically induced astigmatism (SIA), efficacy and safety of two distinct accesses for anterior Artisan Aphakia IOL implantation in patients without capsular support.Methods: Outcome data were collected for all patients who had undergone prepupillary Artisan Aphakia IOL insertion associated with pars plana vitrectomy from October 2016 and June 2022 at Puerta de Hierro‐Majadahonda University Hospital. All those with available preoperative and postoperative IOL master keratometry records were included in the analysis. The results were analysed by the incision type (corneal versus scleral tunnel).Results: Ninety‐seven eyes from 79 patients were included. Average follow up was 2 years. Forty‐five (48%) were corneal incisions and 53 (52%) were scleral tunnels. The main causes were: 33 (32%) eyes with Marfan syndrome, 27 (26%) eyes had a complicated cataract surgery and 23 (23%) eyes had luxation or subluxation of the IOL‐capsule complex. The mean surgically induced astigmatism (SIA) in the scleral tunnel group (1.28 ± 1.15 diopter [D]) was significantly lower than in the corneal incision group (2.20 ± 1.27 D) (p &lt; 0.001). The mean BCVA was better in the scleral tunnel group (0.18 ± 0.33 logMAR) than in the corneal incision group (0.27 ± 0.53 logMAR), although the difference was not significant (p = 0.09). The rate of complications did not show differences between groups. Two eyes (2%) developed corneal decompensation. There were 20 (20.67%) cases of cistoid macular edema (11 in the scleral tunnel group and 10 in the corneal incision group). In the scleral tunnel group, there was a tendency to first day postoperative hypotonia (24.5%) (p = 0.06), in all cases it resolved with conservative measures within 1 week.Conclusions: Scleral‐incision approach is a safe technique that should be performed for anterior Artisan Aphakia IOL implantation in order to reduce SIA and improve BCVA. Intraocular pressure should be monitored throughout the first postoperative week.

Comparison of clinical outcome of small-incision lenticule intrastromal keratoplasty and FS-LASIK for correction of moderate and high hyperopia.

To compare the clinical outcome of small-incision lenticule intrastromal keratoplasty (sLIKE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for correction of moderate and high hyperopia. A case-controlled clinical study was performed. Twenty right eyes of 20 moderate and high hyperopia patients underwent sLIKE (sLIKE group) and 22 right eyes of 22 moderate and high hyperopia patients underwent FS-LASIK (FS-LASIK group) were enrolled in this study from October 2015 to October 2017. Visual acuity, refractive error, corneal thickness, and keratometry were compared between the groups before and 1y postoperatively. The postoperative uncorrected near visual acuity (UNVA) and uncorrected distance visual acuity (UDVA) were improved in the two groups. The UNVA reached J1 in 15 eyes (75.0%) in the sLIKE group and 5 eyes (22.7%) in the FS-LASIK group 1y after surgery (χ 2=11.476, P=0.001). The UDVA was equal or better than the preoperative CDVA in 16 eyes (80.0%) in the sLIKE group and 8 eyes (36.4%) in the FS-LASIK group, respectively (χ 2=8.145, P=0.004). No eyes lost any line of best-corrected visual acuity (BCVA) in either group. The amount of postoperative residual hyperopia in the sLIKE group was significantly less than in the FS-LASIK group (Z=-2.841, P=0.004). The postoperative keratometry and corneal thickness were significantly higher in the sLIKE group than in the FS-LASIK group (t=4.411, 10.279, P<0.001). The SRI and SAI of the sLIKE group were significantly higher than that in the FS-LASIK group. There was no statistically significant difference in mean decentration between the two groups. sLIKE has better visual and refractive outcome than FS-LASIK for correction of moderate and high hyperopia.

PREOPERATIVE AND POSTOPERATIVE KERATOMETRY COMPARISON OF PHACOEMULSIFICATION SURGERY WITH RIGID POSTERIOR CHAMBER INTRAOCULAR LENS IMPLANTATION (PCIOL)

OBJECTIVES:To study and compare pre and post-operative keratometry in phacoemulsication surgery with rigid posterior chamber intraocular lens (PCIOL) implantation. METHOD:Hospital based prospective observational study which included 100 presenile and senile cataract cases with superior scleral incision(5.5mm) phacoemulsication surgery and rigid PCIOL implantation. The data was analyzed by paired 't' test and 'p' value &lt;0.05 considered signicant. The preoperative and postoperative keratometry was compared at 6 weeks. RESULT: There was signicant difference between pre operative and post operative Keratometry (P&lt;0.05) at 6 weeks. Postoperatively majority of patients developed against the rule astigmatism (76% of patients).

Residual astigmatism following cataract surgery

Objective: To determine the amount of residual astigmatism following cataract surgery.&#x0D; Materials and methods: A hospital based observational study was conducted in a tertiary eye hospital, Bangladesh during the period of July, 2013 to June, 2014. Patients was selected for the study who diagnosed as ARC with variable amount of astigmatism (1.5 to 3.5D), and excluded any other ocular pathology or history of previous ocular surgery. Phacoemulsification with PC Toric IOL implantation in all cases. Auto refracto-keratometer was done Preoperative and postoperatively for assessing the astigmatism. Main outcome measured were included preoperative uncorrected visual acuity, postoperative uncorrected visual acuity on 1stPOD, after 1 week and 1month, Preoperative keratometry, Preoperative astigmatism, Postoperative uncorrected keratometry on 1st POD, after 1 week and 1month, Postoperative uncorrected astigmatism on 1stPOD, after 1 week and 1month&#x0D; Results: 30 eyes of 28 patients were assessed in this study. Due to clear corneal incision during phacoemulsification, the steep meridian became flat significantly from pre-operative keratometry 44.329±1.473D (mean±SD) to 30thpost operative keratometry 43.971±1.431D (mean±SD) having p&lt;0.001. On the other-hand the flat meridian became steeper from pre-operative keratometry 42.225±1.471D (mean±SD) to 30thpost operative keratometry 42.421±1.501D (mean±SD) having p&lt;0.001. Preoperative mean astigmatism [Mean±SD] was 2.104±0.319D, after the first postoperative day, mean astigmatism decreased to 0.954±0.494D with p&lt;0.01, and finally after 1 Month there was significant reduction of pre-operative astigmatism to 0.583±0.413D with p&lt;0.0001. So, the mean pre-operative astigmatism decreased significantly in the successive post-operative days.&#x0D; Conclusion: Toric Intraocular lens implantation in phacoemulsification surgery can correct pre-existing corneal astigmatism significantly after one month of surgery.&#x0D; AKMMC J 2022; 13(1) : 42-46

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).

Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis

The implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outcomes. Thus, this study aimed to investigate the influence of ICRS implementation techniques and design on the postoperative biomechanical state and keratometry results. The clinical data of three patients with different stages and patterns of keratoconus were assessed to develop a three-dimensional (3D) patient-specific finite-element model (FEM) of the keratoconic cornea. For each patient, the exact surgery procedure definitions were interpreted in the step-by-step FEM. Then, seven surgical scenarios, including different ICRS designs (complete and incomplete segment), with two surgical implementation methods (tunnel incision and lamellar pocket cut), were simulated. The pre- and postoperative predicted results of FEM were validated with the corresponding clinical data. For the pre- and postoperative results, the average error of 0.4% and 3.7% for the mean keratometry value (text {K}_{text{mean}}) were predicted. Furthermore, the difference in induced flattening effects was negligible for three ICRS types (KeraRing segment with arc-length of 355, 320, and two separate 160) of equal thickness. In contrast, the single and double progressive thickness of KeraRing 160 caused a significantly lower flattening effect compared to the same type with constant thickness. The observations indicated that the greater the segment thickness and arc-length, the lower the induced mean keratometry values. While the application of the tunnel incision method resulted in a lower text {K}_{text{mean}} value for moderate and advanced KC, the induced maximum Von Mises stress on the postoperative cornea exceeded the induced maximum stress on the cornea more than two to five times compared to the pocket incision and the preoperative state of the cornea. In particular, an asymmetric regional Von Mises stress on the corneal surface was generated with a progressive ICRS thickness. These findings could be an early biomechanical sign for a later corneal instability and ICRS migration. The developed methodology provided a platform to personalize ICRS refractive surgery with regard to the patient’s keratoconus stage in order to facilitate the efficiency and biomechanical stability of the surgery.

Comparative Accuracy of Barrett Toric Calculator With and Without Posterior Corneal Astigmatism Measurements and the Kane Toric Formula

PurposeTo compare the accuracy of the Barrett toric calculator with and without posterior corneal astigmatism and the Kane toric calculator. DesignRetrospective cross-sectional study. MethodsThe study included a total of 79 eyes of 79 patients who underwent toric intraocular lens (IOL) insertion during uncomplicated cataract surgery by a single surgeon. Using vector analysis, the mean absolute prediction error, the standard deviation of the prediction error, and the percentage of eyes with a prediction error within ±0.50 diopter (D), ± 0.75 D, and ± 1.00 D were calculated. The IOL Master 700 (Carl Zeiss Meditec AG, Jena, Germany) was used for measuring biometry including posterior corneal astigmatism. The main analysis was designed to provide the clinical outcomes with each formula using the postoperative keratometry values and the measured postoperative IOL axis. Real-world analysis was performed using the preoperative keratometry values and the intended IOL axis. ResultsThere was no significant difference in mean absolute prediction errors calculated with 2 versions of the Barrett toric formula (predicted posterior corneal astigmatism and measured posterior corneal astigmatism) and the Kane toric formula (P > .05). The Barrett toric calculator with predicted and measured posterior corneal astigmatism yielded the best results, with 60.8% <0.50 D prediction error in the main analysis. In the real-world analysis, the Barrett toric calculator with predicted posterior corneal astigmatism showed the best result, with 53.2% <0.50 D prediction error. ConclusionThe Barrett toric formula with and without posterior corneal astigmatism measurements using the IOL Master 700 and the Kane toric formula yielded accurate and comparable outcomes in this single-surgeon analysis. Am J Ophthalmol 2021;221:•••–•••. © 2021 Elsevier Inc. All rights reserved.

Transepithelial Versus Epithelium-Off Corneal Crosslinking for Progressive Keratoconus: Findings From a Cochrane Systematic Review

The purpose of this study was to summarize key findings from a systematic review of the effectiveness and safety of transepithelial corneal crosslinking (CXL) compared with epithelium-off CXL for progressive keratoconus. Cochrane systematic review. We included in our review only randomized controlled trials (RCTs) in which transepithelial and epithelium-off CXL had been compared among participants with progressive keratoconus. The primary outcome was keratoconus stabilization based on post-operative maximum keratometry (Kmax). We adhered to Cochrane methods for trial selection, data extraction, risk of bias evaluation, and data synthesis. Thirteen RCTs with 567 participants (661 eyes) were included; 11 studies compared non-iontophoresis-assisted transepithelial with epithelium-off CXL. Keratoconus stabilization was described as an outcome in 2 studies. The estimated difference in Kmax means (ie, the "mean difference," MD) from meta-analysis of 177 eyes in 5 RCTs indicated that there were no differences between intervention groups in Kmax at 12 months or later (MD: 0.99 diopter [D]; 95% confidence interval: -0.11 to 2.09). Meta-analysis of keratometry and visual acuity outcomes at 12 months or longer after surgery from 2 studies that had compared transepithelial CXL using iontophoresis provided no conclusive evidence of an advantage over epithelium-off CXL. Lack of precision due to small sample sizes, indeterminate risk of bias due to inadequate reporting, and inconsistency in how outcomes were measured and reported among studies make it difficult to state with confidence whether transepithelial CXL confers an advantage over epithelium-off CXL for patients with progressive keratoconus with respect to stabilization of keratoconus, visual acuity, or patient-reported outcomes based on available data.

Long-Term Visual, Refractive and Topographic Outcomes of KeraRings Combined with Accelerated Transepithelial Crosslinking for Management of Different Grades of Progressive Keratoconus: A Retrospective Cohort Study

Purpose: To evaluate long-term visual, refractive, and topographic outcomes of KeraRings intrastromal implantation combined with accelerated transepithelial cross-linking for management of different stages of progressive keratoconus. Materials and Methods: This retrospective cohort study included 70 eyes of 70 patients with Amsler-Krumeich grades 1 to 4 keratoconus. They were divided into two groups: group-A included 37 eyes with grades 1-2 keratoconus, and group-B included 33 eyes with grades 3-4 keratoconus. Both groups underwent combined Keraring implantation with TCXL treatment. The main outcome measures included the preoperative and postoperative visual acuity, refraction, keratometry readings, and pachymetry. Results: At postoperative month 60, group-B exhibited significantly higher values of all mean uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), sphere/cylinder/spherical equivalent/defocus equivalent (DEQ), and K1/K2/Kaverages/Kmax parameters compared to that of group A. However, group-A exhibited better stability of postoperative improvements. Keratoconus progression (KCP) was greater in group-B (45.5%) than group-A (10.8%). Two eyes revealed segments' migration while one eye showed tunnel vascularization and opacification with segments' migration. Conclusion: The diagnostic criteria of preoperative-KCP are not adequate for the diagnosis of postoperative-KCP following ICRS implantation. UDVA and K average posterior seemed to be more sensitive parameters than K max in documenting early postoperative-KCP. We suggest that deterioration of UDVA≥0.10 log MAR and/or K average posterior ≥0.25 D are highly suspicious of post-ring implantation keratoconus progression (PR-KCP). The occurrence of two of the following parameters: Kmax≥0.50 D, Kaverageanterior≥0.50 D, K average posterior ≥0.25 D, or pachymetry≥1.5% thinning, is diagnostic of PR-KCP. The occurrence of two or more of the following parameters: Kmax≥0.50 D, Kaverageanterior≥0.50 D, Kaverageposterior ≥0.25 D, pachymetry≥ 1.5% thinning or UDVA≥0.10 logMAR, is diagnostic of PR-KCP. We also suggest that Kmax≥0.75 D alone is diagnostic of PR-KCP.

Visual and Tomographic Outcomes of a 300° Arc-length ICRS Implantation in Moderate to Advanced Central Keratoconus

To assess the outcomes of implanting a new 300° arc-length intrastromal corneal ring segment (ICRS) in moderate to advanced central hyperprolate keratoconus. Forty-two eyes with moderate to advanced central hyperprolate keratoconus were evaluated before and after implanting an inferior 300° ICRS (AJL Ophthalmic). The clinical measurements taken included manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuity (logMAR scale), and corneal tomographic analysis (Sirius; Costruzioni Strumenti Oftalmici). Changes in the anterior and posterior corneal surfaces and the root mean square (RMS) for coma-like aberrations for a pupil size of 4.5 mm were evaluated. All examinations were performed before surgery and 6 months after surgery. The mean UDVA improved from 1.12 ± 0.48 logMAR preoperatively to 0.73 ± 0.37 logMAR postoperatively (P < .0001). The mean CDVA changed from 0.33 ± 0.20 to 0.20 ± 0.11 logMAR (P < .0001). Postoperatively, the CDVA improved by two or more lines in 45.2% of the eyes and increased by one line in 19.04%, and none of the patients lost lines of CDVA. All of the anterior and posterior corneal tomographic parameters analyzed were significantly improved after surgery, except posterior flat keratometry, which remained unchanged. In 80.95% of the eyes, the postoperative mean keratometry was 50.00 diopters or less. The 6-month RMS for coma-like aberrations also declined significantly from 1.57 ± 0.68 to 1.06 ± 0.42 µm after surgery (P < .0001). These results suggest that implanting a 300° arc-length ICRS is a safe and effective procedure for treating patients with moderate to advanced central hyperprolate keratoconus and clear cornea. [J Refract Surg. 2021;37(4):249-255.].

Five-Year Occurrence and Management of Central Toxic Keratopathy After Femtosecond Laser-Assisted LASIK.

To report the 5-year occurrence, management, and outcomes of 12 eyes diagnosed as having central toxic keratopathy (CTK) after femtosecond laser-assisted in situ keratomileusis (FS-LASIK). A retrospective chart review was conducted on 20,622 FS-LASIK procedures performed at a single site from January 2015 to December 2019 to identify patients diagnosed as having central toxic keratopathy. Preoperative and postoperative visual acuity, refraction, and imaging were recorded and analyzed. CTK occurred in 12 eyes of 8 patients after FSLASIK. A total of 75% of eyes were diagnosed during an outbreak that happened over 2 months and the remaining 25% were considered sporadic. Five eyes were treated with flap lift and irrigation and 7 eyes were treated non-surgically. The average time to resolution of CTK in eyes that underwent flap lift and irrigation was 53 days compared to 33 days in eyes treated non-surgically. All 5 eyes treated with flap lift and irrigation ultimately achieved uncorrected distance visual acuity of 0.1 logMAR or better, whereas only 3 of 7 eyes treated non-surgically achieved the same. At the final postoperative visit, the eyes treated with flap lift and irrigation measured on average 14 µm thinner and 1.60 diopters (D) flatter than the expected postoperative pachymetry and keratometry, respectively. Those treated non-surgically were on average 28 µm thinner and 1.70 D flatter than expected. CTK is a rare complication of FS-LASIK but can occur in clusters. Although management of CTK is debated, flap lift and irrigation may lead to better visual acuity and refractive and anatomic outcomes in some cases. [J Refract Surg. 2021;37(1):25-31.].

Effect of capsular tension ring on refractive results in cases with pseudoexfoliation syndrome.

To investigate the effect of capsular tension rings (CTRs) on postoperative refractive results in patients with pseudoexfoliation (PSX) syndrome. Sixty-nine patients with PSX syndrome who had uncomplicated cataract surgery between March 2016 and February 2019 were reviewed retrospectively. The patients were divided into two groups. The 35 patients in Group 1 received CTRs prior to intraocular lens implantation during cataract surgery, and the 34 patients in Group 2 had cataract surgery without CTRs. Significant zonular weakness, uncontrolled glaucoma, and ocular pathologies causing low visual acuity were excluded. The preoperative and postoperative keratometry and autorefraction measurements, preoperative expected refractive values, and absolute refractive error were recorded. The mean ages of patients were 73.54 ± 9.78 years in Group 1 and 72.23 ± 6.72 years in Group 2 (p = 0.521). There was no statistically significant difference between Group 1 and Group 2 in terms of expected preoperative refraction values (-0.52 ± 0.12,-0.56 ± 0.08, respectively, p = 0.118). There was a statistically significant difference in postoperative spherical equivalent values between Group 1 and Group 2 (-0.05 ± 0.97 and -0.92 ± 0.57, respectively, p < 0.01). A statistically significant difference was found between the two groups in terms of absolute refractive error (0.46 ± 0.74 in Group 1 and -0.34 ± 0.59 in Group 2 p < 0.01). CTR implantation causes hyperopic shift, which should be taken into consideration when calculating the lens power of intraocular lens in patients with PSX syndrome.